bims-mosdis 2021-10-24 papers

bims-mosdis

Biomed News

on Mosquito distribution and disease

Issue of 2021–10–24
27 papers selected by
Richard Halfpenny, Staffordshire University

Assessing Anopheles vector species diversity and transmission of malaria in four health districts along the borders of Côte d'Ivoire.
The Extrinsic Incubation Period of Zika Virus in Florida Mosquitoes Aedes aegypti and Ae. albopictus.
Metabolic Resistance in Permethrin-Resistant Florida Aedes aegypti (Diptera: Culicidae).
Anthropogenic changes and associated impacts on vector-borne diseases.
Overabundance of Asaia and Serratia Bacteria Is Associated with Deltamethrin Insecticide Susceptibility in Anopheles coluzzii from Agboville, Côte d'Ivoire.
Spatial Distribution of Aedes aegypti Oviposition Temporal Patterns and Their Relationship with Environment and Dengue Incidence.
Entomological survey in two communes with residual malaria transmission in Gia Lai Province in the central highlands of Vietnam.
The impact of mosquito proof lids of underground tanks "tanka" on the breeding of Anopheles stephensi in a village in western Rajasthan, India.
Surveillance Studies Reveal Diverse and Potentially Pathogenic-Incriminated Vector Mosquito Species across Major Botswana Touristic Hotspots.
High Prevalence of Rickettsia bellii in Mosquitoes From Eastern China.
Risk factors for occurrence and abundance of Aedes aegypti and Aedes bromeliae at hotel compounds in Zanzibar.
The Effects of Host Availability and Fitness on Aedes albopictus Blood Feeding Patterns in New York.
Airport Malaria in Non-Endemic Areas: New Insights into Mosquito Vectors, Case Management and Major Challenges.
Entomological Risk Assessment for Dengue Virus Transmission during 2016-2020 in Kamphaeng Phet, Thailand.
National Monitoring of Mosquito Populations and Molecular Analysis of Flavivirus in the Republic of Korea in 2020.
Host Associations of Culex pipiens: A Two-Year Analysis of Bloodmeal Sources and Implications for Arboviral Transmission in Southeastern Virginia.
The Rare, the Best: Spread of Antimalarial-Resistant Plasmodium falciparum Parasites by Anopheles Mosquito Vectors.
Invasive Malaria Vector Anopheles stephensi Mosquitoes in Sudan, 2016-2018.
Intensive West Nile Virus Circulation in Serbia in 2018-Results of Integrated Surveillance Program.
Genetic Diversity and Population Structure of the Asian Tiger Mosquito (Aedes albopictus) in Vietnam: Evidence for Genetic Differentiation by Climate Region.
Human attractive cues and mosquito host-seeking behavior.
Distribution and Molecular Identification of Culex pipiens and Culex tritaeniorhynchus as Potential Vectors of Rift Valley Fever Virus in Jazan, Saudi Arabia.
Global dengue importation: a systematic review.
Improving the DNA Barcode Library of Mosquito Species With New Identifications and Discoveries in North-Central Argentina.
Spatiotemporal Analysis of West Nile Virus Epidemic in South Banat District, Serbia, 2017-2019.
Emerging and Re-emerging Vector-Borne Infectious Diseases and the Challenges for Control: A Review.
Detection of Saint Louis Encephalitis virus in two Brazilian States.

Malar J. 2021 Oct 18. 20(1): 409

Assessing Anopheles vector species diversity and transmission of malaria in four health districts along the borders of Côte d'Ivoire.

Firmain N Yokoly, Julien B Z Zahouli, Graham Small, Allassane F Ouattara, Millicent Opoku, Dziedzom K de Souza, Benjamin G Koudou.

   BACKGROUND: Although malaria and Anopheles mosquito vectors are highly prevalent in Côte d'Ivoire, limited data are available to help understand the malaria vector density and transmission dynamics in areas bordering the country. To address this gap, the Anopheles mosquito species diversity, the members of the Anopheles gambiae complex and the transmission of malaria were assessed in four health districts along the borders of Côte d'Ivoire.
METHODS: From July 2016 through December 2016 and July 2017 through December 2017, adult Anopheles mosquitoes were collected in four health districts of Côte d'Ivoire (Aboisso, Bloléquin, Odienné and Ouangolodougou) using standardized window exit trap (WET) and pyrethrum knockdown spray collection (PSC) methods. The collected mosquitoes were identified morphologically at species level and the members of the An. gambiae complex were separated using short interspersed nuclear element-based polymerase chain reaction (SINE-PCR). Anopheles gambiae sensu lato (s.l.), Anopheles funestus s.l. and Anopheles nili specimens were analysed for malaria Plasmodium parasite detection using the cytochrome oxidase I gene (COX-I), and malaria prevalence among human population through local Ministry of Health (MoH) statistical yearbooks.
RESULTS: A total of 281 female Anopheles were collected in Aboisso, 754 in Bloléquin, 1319 in Odienné and 2443 in Ouangolodougou. Seven Anopheles species were recorded including An. gambiae s.l. (94.8-99.1%) as the main vector, followed by An. funestus s.l. (0.4-4.3%) and An. nili (0-0.7%). Among An. gambiae s.l., Anopheles coluzzii represented the predominant species in Aboisso (89.2%) and Bloléquin (92.2%), while An. gambiae sensu stricto (s.s.) was the major species in Odienné (96.0%) and Ouangolodougou (94.2%). The Plasmodium sporozoite infection rate in An. gambiae s.l. was highest in Odienné (11.0%; n = 100) followed by Bloléquin (7.8%, n = 115), Aboisso (3.1%; n = 65) and Ouangologoudou (2.5%; n = 120). In An. funestus s.l., Plasmodium falciparum sporozoite infection rate was estimated at 6.2% (n = 32) in Bloléquin, 8.7% (n = 23) in Odienné. No An. funestus s.l. specimens were found infected with P. falciparum sporozoite infection in Ouangolodougou and Aboisso. No P. falciparum sporozoite was detected in An. nili specimens in the four health districts. Among the local human populations, malaria incidence was higher in Odienné (39.7%; n = 45,376) and Bloléquin (37.6%; n = 150,205) compared to that in Ouangolodougou (18.3%; n = 131,629) and Aboisso (19.7%; n = 364,585).
CONCLUSION: Anopheles vector species diversity, abundance and Plasmodium sporozoite infection were high within the health districts along the borders of the country of Côte d'Ivoire, resulting in high malaria transmission among the local populations. Anopheles gambiae s.l. and An. funestus s.l. were found to be highly infected with Plasmodium in the health districts of Bloléquin and Odienné where higher malaria incidence was observed than the other districts. This study provides important information that can be used to guide Côte d'Ivoire National Malaria Control Programme for vector control decision-making, mainly in districts that are at the country borders.

Keywords:  Anopheles; Border health district; Côte d’Ivoire; Malaria; Plasmodium

DOI:  https://doi.org/10.1186/s12936-021-03938-1
Pathogens. 2021 Sep 28. pii: 1252. [Epub ahead of print]10(10):

The Extrinsic Incubation Period of Zika Virus in Florida Mosquitoes Aedes aegypti and Ae. albopictus.

Rebecca A Zimler, Barry W Alto.

  The Asian genotype of Zika virus (ZIKV) emerged in Brazil in 2015 and subsequently spread throughout the Americas. In July 2016, Florida experienced its first locally acquired ZIKV infection in the continental U.S. Concerns about health risks from ZIKV infection have increased the need to investigate the interactions between potential mosquito vectors and ZIKV. The time it takes for an arbovirus to propagate within a mosquito, and become transmissible, is the extrinsic incubation period (EIP). The EIP for potential mosquito vectors in Florida is unknown. To address this gap in the understanding of ZIKV epidemiology, Florida Aedes aegypti (L.) and Ae. albopictus (Skuse) were orally exposed to ZIKV infected blood meals and fully engorged mosquitoes were held at a constant temperature of 28 °C through the duration of the experiment. Saliva expectorates were collected from cohorts of mosquitoes and tested for the presence of ZIKV at three-day intervals over a period of 24 days to allow for an evaluation of the EIP of the emergent Asian lineage of ZIKV. High rates of infected bodies in Ae. albopictus (75-94%) and Ae. aegypti (68-86%) were observed throughout the incubation period, which did not differ by species. Higher rates of disseminated infection were observed later during the incubation period but did not differ between species. We calculated the 50% EIP to be shorter in Ae. albopictus than Ae. aegypti (16.2 and 18.2 days post infection, respectively). The competence for ZIKV observed in both species may contribute to high rates of ZIKV transmission in Florida populations.

Keywords:  Zika virus infection; arbovirus mosquito vectors; emerging pathogen

DOI:  https://doi.org/10.3390/pathogens10101252
Insects. 2021 Sep 24. pii: 866. [Epub ahead of print]12(10):

Metabolic Resistance in Permethrin-Resistant Florida Aedes aegypti (Diptera: Culicidae).

Sierra M Schluep, Eva A Buckner.

  Aedes aegypti is the principal mosquito vector for many arthropod-borne viruses (arboviruses) including dengue, chikungunya, and Zika. In the United States, excessive permethrin use has led to a high frequency of resistance in mosquitoes. Insecticide resistance is a significant obstacle in the struggle against vector-borne diseases. To help overcome metabolic resistance, synergists that inhibit specific metabolic enzymes can be added to formulated pyrethroid products. Using modified CDC bottle bioassays, we assessed the effect of three inhibitors (piperonyl butoxide (PBO), which inhibits oxidase activity; S.S.S-tributyl phosphorotrithioate (DEF), which inhibits esterase activity; and diethyl maleate (DM), which inhibits glutathione transferase activity) + permethrin. We performed these against 20 Florida Ae. aegypti populations, all of which were resistant to permethrin. Our data indicated that 11 out of 20 populations (55%) exhibited metabolic resistance. Results revealed 73% of these populations had significant increases in mortality attributed to DEF + permethrin, 64% to PBO + permethrin, and 55% to DM + permethrin compared to permethrin alone. Currently, PBO is the only metabolic enzyme inhibitor added to formulated pyrethroid products used for adult mosquito control. Our results suggest that the DEF and DM inhibitors could also be useful additives in permethrin products, especially against metabolically resistant Ae. aegypti mosquitoes. Moreover, metabolic assays should be conducted to better inform mosquito control programs for designing and implementing integrated vector management strategies.

Keywords:  Aedes aegypti; PBO; inhibitors; metabolic resistance; permethrin; pyrethroids

DOI:  https://doi.org/10.3390/insects12100866
Trends Parasitol. 2021 Oct 19. pii: S1471-4922(21)00238-5. [Epub ahead of print]

Anthropogenic changes and associated impacts on vector-borne diseases.

André B B Wilke, Giovanni Benelli, John C Beier.

  Urbanization impacts the community composition, abundance, and richness of mosquitoes. As urbanization processes increase globally, it is important to better understand the biodiversity loss caused by anthropogenic changes and associated impacts on vector-borne diseases. Mosquito surveillance and control are key for reducing the risk of mosquito-borne pathogen transmission.

Keywords:  Aedes aegypti; Aedes albopictus; Zika virus; arbovirus; dengue virus; vector control

DOI:  https://doi.org/10.1016/j.pt.2021.09.013
Microbiol Spectr. 2021 Oct 20. e0015721

Overabundance of Asaia and Serratia Bacteria Is Associated with Deltamethrin Insecticide Susceptibility in Anopheles coluzzii from Agboville, Côte d'Ivoire.

Bethanie Pelloquin, Mojca Kristan, Constant Edi, Anne Meiwald, Emma Clark, Claire L Jeffries, Thomas Walker, Nsa Dada, Louisa A Messenger.

  Insecticide resistance among mosquito species is now a pervasive phenomenon that threatens to jeopardize global malaria vector control efforts. Evidence of links between the mosquito microbiota and insecticide resistance is emerging, with significant enrichment of insecticide degrading bacteria and enzymes in resistant populations. Using 16S rRNA amplicon sequencing, we characterized and compared the microbiota of Anopheles coluzzii in relation to their deltamethrin resistance and exposure profiles. Comparisons between 2- and 3-day-old deltamethrin-resistant and -susceptible mosquitoes demonstrated significant differences in microbiota diversity. Ochrobactrum, Lysinibacillus, and Stenotrophomonas genera, each of which comprised insecticide-degrading species, were significantly enriched in resistant mosquitoes. Susceptible mosquitoes had a significant reduction in alpha diversity compared to resistant individuals, with Asaia and Serratia dominating microbial profiles. There was no significant difference in deltamethrin-exposed and -unexposed 5- to 6-day-old individuals, suggesting that insecticide exposure had minimal impact on microbial composition. Serratia and Asaia were also dominant in 5- to 6-day-old mosquitoes, which had reduced microbial diversity compared to 2- to 3-day-old mosquitoes. Our findings revealed significant alterations of Anopheles coluzzii microbiota associated with deltamethrin resistance, highlighting the potential for identification of novel microbial markers for insecticide resistance surveillance. qPCR detection of Serratia and Asaia was consistent with 16S rRNA sequencing, suggesting that population-level field screening of bacterial microbiota may be feasibly integrated into wider resistance monitoring, if reliable and reproducible markers associated with phenotype can be identified. IMPORTANCE Control of insecticide-resistant vector populations remains a significant challenge to global malaria control and while substantial progress has been made elucidating key target site mutations, overexpressed detoxification enzymes and alternate gene families, the contribution of the mosquito microbiota to phenotypic insecticide resistance has been largely overlooked. We focused on determining the effects of deltamethrin resistance intensity on Anopheles coluzzii microbiota and identifying any microbial taxa associated with phenotype. We demonstrated a significant reduction in microbial diversity between deltamethrin-resistant and -susceptible mosquitoes. Insecticide degrading bacterial species belonging to Ochrobactrum, Lysinibacillus, and Stenotrophomonas genera were significantly enriched in resistant mosquitoes, while Asaia and Serratia dominated microbial profiles of susceptible individuals. Our results revealed significant alterations of Anopheles coluzzii microbiota associated with deltamethrin resistance, highlighting the potential for identification of novel microbial markers for surveillance and opportunities for designing innovative control techniques to prevent the further evolution and spread of insecticide resistance.

Keywords:  Anopheles coluzzii; Asaia; Côte d’Ivoire; Serratia; deltamethrin; insecticide resistance; malaria; microbiota

DOI:  https://doi.org/10.1128/Spectrum.00157-21
Insects. 2021 Oct 09. pii: 919. [Epub ahead of print]12(10):

Spatial Distribution of Aedes aegypti Oviposition Temporal Patterns and Their Relationship with Environment and Dengue Incidence.

Verónica Andreo, Ximena Porcasi, Claudio Guzman, Laura Lopez, Carlos M Scavuzzo.

  Aedes aegypti, the mosquito species transmitting dengue, zika, chikungunya and yellow fever viruses, is fully adapted to thrive in urban areas. The temporal activity of this mosquito, however, varies within urban areas which might imply different transmission risk. In this work, we hypothesize that temporal differences in mosquito activity patterns are determined by local environmental conditions. Hence, we explore the existence of groups of temporal patterns in weekly time series of Ae. aegypti ovitraps records (2017-2019) by means of time series clustering. Next, with the aim of predicting risk in places with no mosquito field data, we use machine learning classification tools to assess the association of temporal patterns with environmental variables derived from satellite imagery and predict temporal patterns over the city area to finally test the relationship with dengue incidence. We found three groups of temporal patterns that showed association with land cover diversity, variability in vegetation and humidity and, heterogeneity measured by texture indices estimated over buffer areas surrounding ovitraps. Dengue incidence on a neighborhood basis showed a weak but positive association with the percentage of pixels belonging to only one of the temporal patterns detected. The understanding of the spatial distribution of temporal patterns and their environmental determinants might then become highly relevant to guide the allocation of prevention and potential interventions. Further investigation is still needed though to incorporate other determinants not considered here.

Keywords:  Earth Observation; clustering; machine learning; mosquitoes; time series

DOI:  https://doi.org/10.3390/insects12100919
Malar J. 2021 Oct 16. 20(1): 403

Entomological survey in two communes with residual malaria transmission in Gia Lai Province in the central highlands of Vietnam.

Thai Quang Nguyen, Manh Duc Nguyen, Vinh Xuan Pham, Huan Mah Ro, Michael D Edstein, Weng K Chow, Nicholas J Martin, Jeffrey C Hertz, Maysa T Motoki.

   BACKGROUND: In 2018, the National Malaria Control Programme in Vietnam switched from prioritizing malaria control to elimination. However, with the ongoing elimination programme, there are still areas where residual malaria transmission persists, including the central highlands. This entomological survey was conducted to evaluate Anopheles diversity and host-seeking activity of Anopheles vectors in two communes with very low malaria transmission in Gia Lai Province.
METHODS: Anopheles species were collected in Ia DReh commune and Ia KDam commune, Gia Lai Province in the central highlands of Vietnam. Collections were conducted using human-baited double net trap, light trap and manual aspiration collections around cattle sheds, in the dry and rainy season. Mosquito specimens were identified morphologically, and members of species complexes were distinguished molecularly. Mosquito night-feeding patterns were investigated during the dry and rainy seasons.
RESULTS: Overall, 18,835 specimens including 19 taxa were collected in Ia KDam and Ia DReh communes. These included the primary malaria vectors, Anopheles dirus and Anopheles minimus, and other secondary vector species. Anopheles dirus was observed to be an anthropophilic species, whereas An. minimus and a number of secondary vectors were observed to be zoophilic. Anopheles vagus was the dominant species, followed by Anopheles sinensis and Anopheles peditaeniatus. The majority of specimens were collected in the rainy season due to the relatively large number of An. vagus, while An. peditaeniatus, An. dirus, Anopheles kochi, Anopheles monstrosus and Anopheles tessellatus were collected in greater numbers during the dry season. The peak of host-seeking activity for An. dirus, An. sinensis, and An. vagus was between 18.00 and 19.00 h.
CONCLUSION: This study provided information on the diversity, seasonal prevalence and behaviour of Anopheles at the study sites. Identifying the diverse mosquito fauna in the central highlands of Vietnam allows species-specific control measures to be implemented by the National Programme to reduce malaria in areas of very low malaria transmission. The peak Anopheles host-seeking activity observed in this study was between 18.00 and 23.00 h, which highlights the need to better characterize Anopheles behaviour in this region of Vietnam to inform on vector control strategies.

Keywords:  Anopheles diversity; Host-seeking activity; Malaria; Vietnam

DOI:  https://doi.org/10.1186/s12936-021-03941-6
Malar J. 2021 Oct 19. 20(1): 412

The impact of mosquito proof lids of underground tanks "tanka" on the breeding of Anopheles stephensi in a village in western Rajasthan, India.

Himmat Singh, Sanjeev Kumar Gupta, Kumar Vikram, Rekha Saxena, Amit Sharma.

   BACKGROUND: Western Rajasthan in India has a typical desert climate. Until the introduction of the canal water irrigation system, malaria was an unstable and seasonal occurrence. Due to the scarcity of water, the community practised having one large underground tank (locally known as the tanka) in their house to collect rainwater for long-term household use. Anopheles stephensi, one of the major malaria vectors, breeds in improperly covered "tankas" if not properly covered and harbours a vector population throughout the year.
METHODS: Two villages, Ajasar (intervention) and Tota (control), with similar ecological features, were selected for the study. A pre-intervention survey was carried out in both villages to assess the presence and quality of lids of tankas, and mosquito breeding and adult mosquito density. Awareness of the community about malaria and mosquitoes was also assessed during the pre-intervention period. In the intervention village, damaged or improper lids were replaced with improved mosquito proof polyvinyl chloride plastic (PVC) lids and lasted longer than the conventional lids. The fitness of the lids was assessed one year after the pre-intervention survey. The entomological assessment was carried out in both intervention and non-intervention villages. The level of community awareness about malaria, mosquitoes, their breeding places, and the role of tankas in malaria transmission was assessed both during pre- and post-intervention.
RESULTS: During the pre-intervention survey, Anopheles breeding was found in 22.1% (58/262) of tankas in the intervention village and 27.1% (19/70) in tankas in the control village. Mosquito breeding was observed in the tankas with iron lids in the intervention village (48.3%) and the control village (42.1%). In the intervention village, out of 262 tankas in the village, 200 lids were replaced, resulting in the complete absence of mosquito breeding. In the pre-intervention survey conducted in May 2018, Anopheles stephensi consisted of 46% of adult mosquitoes in the intervention village and 55% in the control village. Its density was significantly reduced to 0.55 per man-hour (94.95%) and 0.22 per man-hour (97.8%) in the post-intervention survey in June 2018 and a follow-up survey in May 2019, respectively, in the intervention village.
DISCUSSION: The density of Anopheles stephensi adults was reduced significantly (97.8%) in the intervention village due to complete prevention of breeding in the underground tankas in the intervention village as compared to the control with no density reduction. The awareness level of the community was also improved due to their involvement in the study.
CONCLUSION: Provision of proper metal lids or replacement of damaged lids on underground water storage tanks as an environmental management approach prevented the breeding of the malaria vector, Anopheles stephensi, in a desert village in western Rajasthan.

Keywords:  Anopheles stephensi; Malaria; Tankas; Western Rajasthan

DOI:  https://doi.org/10.1186/s12936-021-03939-0
Insects. 2021 Oct 06. pii: 913. [Epub ahead of print]12(10):

Surveillance Studies Reveal Diverse and Potentially Pathogenic-Incriminated Vector Mosquito Species across Major Botswana Touristic Hotspots.

Mmabaledi Buxton, Casper Nyamukondiwa, Ryan J Wasserman, Victor Othenin-Girard, Romain Pigeault, Philippe Christe, Olivier Glaizot.

  Vector mosquitoes contribute significantly to the global burden of diseases in humans, livestock and wildlife. As such, the spatial distribution and abundance of mosquito species and their surveillance cannot be ignored. Here, we surveyed mosquito species across major tourism hotspots in semi-arid Botswana, including, for the first time, the Central Kalahari Game Reserve. Our results reported several mosquito species across seven genera, belonging to Aedes, Anopheles, Culex, Mansonia, Mimomyia, Coquillettidia and Uranotaenia. These results document a significant species inventory that may inform early warning vector-borne disease control systems and likely help manage the risk of emerging and re-emerging mosquito-borne infections.

Keywords:  Central Kalahari Game Reserve; Chobe enclave; Okavango; emerging–re-emerging diseases; mosquito-borne infections; vector mosquitoes

DOI:  https://doi.org/10.3390/insects12100913
J Med Entomol. 2021 Oct 19. pii: tjab177. [Epub ahead of print]

High Prevalence of Rickettsia bellii in Mosquitoes From Eastern China.

Feng Li, Junhua Tian, Lin Wang, Zhengpei Yang, Miao Lu, Xincheng Qin, Hongqing Zhao, Jintao Chen, Kun Li.

  Mosquitoes are the most important vectors carrying significant numbers of human pathogens. Recent studies implicated that mosquitoes play an important role in circulation and transmission of multiple Rickettsia species. In this study, Rickettsia bellii was identified in four mosquito species (Culex pipiens, C. tritaeniorhynchus, Aedes albopictus, and Anopheles sinensis) collected from three Eastern China provinces during 2019-2020. Rickettsia bellii was detected in 37.50 and 26.32% of the C. pipiens pools from Beijing and Jiangsu province, respectively. In C. tritaeniorhynchus and An. sinensis from Shandong, the infection rate is 20.00 and 6.25%, respectively. Additionally, three Ae. albopictus pools (3/42, 7.14%) from Beijing were also detected positive for R. bellii. Genetic and phylogenetic analysis on 16S, gltA, and groEL genes indicates that sequences from all these strains are highly homologous and closely related to other R. bellii strains. This is the first report that Ae. albopictus and C. tritaeniorhynchus harbor R. bellii. The wide host range and high infection rate in certain areas may dramatically increase the exposure of R. bellii to human and other vertebrates. The role of mosquitoes in transmission of rickettsiosis and its potential risk to public health should be further considered.

Keywords:  Ae. albopictus; C. tritaeniorhynchus; Eastern China; R. bellii; mosquitoe

DOI:  https://doi.org/10.1093/jme/tjab177
Parasit Vectors. 2021 Oct 22. 14(1): 544

Risk factors for occurrence and abundance of Aedes aegypti and Aedes bromeliae at hotel compounds in Zanzibar.

Ayubo Kampango, Peter Furu, Divakara L Sarath, Khamis A Haji, Flemming Konradsen, Karin L Schiøler, Michael Alifrangis, Fatma Saleh, Christopher W Weldon.

   BACKGROUND: A field survey was performed to investigate local environmental factors promoting occurrence and abundance of Aedes aegypti and Ae. bromeliae mosquitoes at hotel compounds in the south-east coastal region of Zanzibar Island.
METHODS: The potential risk factors were determined using generalized linear mixed models. Aedes (Stegomyia) spp. indices such as container index (CI) and pupae per container (PPC) index were also estimated.
RESULTS: Aedes aegypti and Ae. bromeliae were the most abundant vector species, accounting for 70.8% of all Aedes mosquitoes collected. The highest CI was observed for plastic containers irrespective of the season, whereas the highest PPC was observed for coconut shells and aluminium containers in the rainy and dry seasons, respectively. The risk of Aedes mosquito occurrence and abundance were significantly associated with presence of plastic containers, coconut shells, used tyres and steel containers. These were discarded in shaded places, in the open and gardens, or found in plant nurseries.
CONCLUSION: This study shows that Aedes species of global health significance occur at hotel compounds on this part of Zanzibar Island. The occurrence and abundance are sustained by the presence of abundant and poorly managed solid wastes and containers used for gardening tasks. This highlights an urgent need for the adoption of area-wide environmentally sustainable Aedes mosquito management interventions that also integrate solid waste management and ornamental plant production practices for reducing the risk of arboviral disease epidemics.

Keywords:  Aedes mosquitoes; Arbovirus vectors; Hotels; Solid waste; Zanzibar

DOI:  https://doi.org/10.1186/s13071-021-05005-9
Am J Trop Med Hyg. 2021 Oct 18. pii: tpmd210157. [Epub ahead of print]

The Effects of Host Availability and Fitness on Aedes albopictus Blood Feeding Patterns in New York.

Kara Fikrig, Elisabeth Martin, Sharon Dang, Kimberly St Fleur, Henry Goldsmith, Sophia Qu, Hannah Rosenthal, Sylvie Pitcher, Laura C Harrington.

Aedes albopictus is a competent vector of numerous pathogens, representing a range of transmission cycles involving unique hosts. Despite the important status of this vector, variation in its feeding patterns is poorly understood. We examined the feeding patterns of Ae. albopictus utilizing resting collections in Long Island, NY, and contextualized blood meal sources with host availability measured by household interviews and camera traps. We identified 90 blood meals, including 29 humans, 22 cats, 16 horses, 12 opossums, 5 dogs, 2 goats, and 1 each of rabbit, rat, squirrel, and raccoon. This is only the third study of Ae. albopictus blood feeding biology that quantitatively assessed domestic host availability and is the first to do so with wild animals. Host feeding indices showed that cats and dogs were fed upon disproportionately often compared with humans. Forage ratios suggested a tendency to feed on cats and opossums and to avoid raccoons, squirrels, and birds. This feeding pattern was different from another published study from Baltimore, where Ae. albopictus fed more often on rats than humans. To understand whether these differences were because of host availability or mosquito population variation, we compared the fitness of New York and Baltimore Ae. albopictus after feeding on rat and human blood. In addition, we examined fitness within the New York population after feeding on human, rat, cat, horse, and opossum blood. Together, our results do not indicate major mosquito fitness differences by blood hosts, suggesting that fitness benefits do not drive Northeastern Ae. albopictus feeding patterns.

DOI: https://doi.org/10.4269/ajtmh.21-0157
Microorganisms. 2021 Oct 16. pii: 2160. [Epub ahead of print]9(10):

Airport Malaria in Non-Endemic Areas: New Insights into Mosquito Vectors, Case Management and Major Challenges.

Leo Dilane Alenou, Josiane Etang.

  Despite the implementation of preventive measures in airports and aircrafts, the risk of importing Plasmodium spp. infected mosquitoes is still present in malaria-free countries. Evidence suggests that mosquitoes have found a new alliance with the globalization of trade and climate change, leading to an upsurge of malaria parasite transmission around airports. The resulting locally acquired form of malaria is called Airport malaria. However, piecemeal information is available, regarding its epidemiological and entomological patterns, as well as the challenges in the diagnosis, treatment, and prevention. Understanding these issues is a critical step towards a better implementation of control strategies. To cross reference this information, we conducted a systematic review on 135 research articles published between 1969 (when the first cases of malaria in airports were reported) and 2020 (i.e., 51 years later). It appears that the risk of malaria transmission by local mosquito vectors in so called malaria-free countries is not zero; this risk is more likely to be fostered by infected vectors coming from endemic countries by air or by sea. Furthermore, there is ample evidence that airport malaria is increasing in these countries. From 2010 to 2020, the number of cases in Europe was 7.4 times higher than that recorded during the 2000-2009 decade. This increase may be associated with climate change, increased international trade, the decline of aircraft disinsection, as well as delays in case diagnosis and treatment. More critically, current interventions are weakened by biological and operational challenges, such as drug resistance in malaria parasites and vector resistance to insecticides, and logistic constraints. Therefore, there is a need to strengthen malaria prevention and treatment for people at risk of airport malaria, and implement a rigorous routine entomological and epidemiological surveillance in and around airports.

Keywords:  Anopheles mosquitoes; Plasmodium spp.; air transportation; malaria; non-endemic areas

DOI:  https://doi.org/10.3390/microorganisms9102160
Pathogens. 2021 Sep 24. pii: 1234. [Epub ahead of print]10(10):

Entomological Risk Assessment for Dengue Virus Transmission during 2016-2020 in Kamphaeng Phet, Thailand.

Thanyalak Fansiri, Darunee Buddhari, Nattaphol Pathawong, Arissara Pongsiri, Chonticha Klungthong, Sopon Iamsirithaworn, Anthony R Jones, Stefan Fernandez, Anon Srikiatkhachorn, Alan L Rothman, Kathryn B Anderson, Stephen J Thomas, Timothy P Endy, Alongkot Ponlawat.

  Individual houses with high risks of dengue virus (DENV) transmission might be a source of virus transmission within the neighborhood. We conducted an entomological risk assessment for DENV transmission at the household level, comprising family cohort members residing in the same location, to assess the risk for dengue virus transmitted by mosquito vectors. The studies were conducted in Kamphaeng Phet Province, Thailand, during 2016-2020. Entomological investigations were performed in 35 cohort families on day 1 and day 14 after receiving dengue case reports. DENV was found in 22 Aedes samples (4.9%) out of 451 tested samples. A significantly higher DENV infection rate was detected in vectors collected on day 1 (6.64%) compared to those collected on day 14 (1.82%). Annual vector surveillance was carried out in 732 houses, with 1002 traps catching 3653 Aedes females. The majority of the 13,228 water containers examined were made from plastic and clay, with used tires serving as a primary container, with 59.55% larval abundance. Larval indices, as indicators of dengue epidemics and to evaluate disease and vector control approaches, were calculated. As a result, high values of larval indices indicated the considerably high risk of dengue transmission in these communities.

Keywords:  Aedes aegypti; Aedes albopictus; Kamphaeng Phet; Thailand; dengue; mosquito surveillance

DOI:  https://doi.org/10.3390/pathogens10101234
Microorganisms. 2021 Oct 02. pii: 2085. [Epub ahead of print]9(10):

National Monitoring of Mosquito Populations and Molecular Analysis of Flavivirus in the Republic of Korea in 2020.

Min-Goo Seo, Hak Seon Lee, Sung-Chan Yang, Byung-Eon Noh, Tae-Kyu Kim, Wook-Gyo Lee, Hee Il Lee.

  The Korea Disease Control and Prevention Agency has established centers at 16 locations to screen vector populations and pathogens. The aims of this study were to determine the relative spatiotemporal distributions of mosquitoes that are flavivirus vectors, and to correlate them with instances of flaviviral disease in the Republic of Korea (ROK). We collected 67,203 mosquitoes in traps at 36 collection sites in 30 urban regions and migratory bird habitats in 2020. The trap index was 36.6, and the predominant mosquito species were the Culex pipiens complex, Armigeres subalbatus, Aedes albopictus, Aedes vexans, and Culex tritaeniorhynchus. The mosquitoes were pooled into 4953 pools to monitor flavivirus infection. We determined that the minimum infection rate of flavivirus was 0.01%. Japanese encephalitis virus (JEV) was detected in only seven pools of Culex orientalis from Sangju, and we isolated JVE from two pools. All detected JEV was found to be genotype V by phylogenetic analysis. To the best of our knowledge, this is the first study to isolate genotype V JVE from Culex orientalis in the ROK. Subsequent geographical and ecological studies on mosquitoes will help improve our understanding of the relative risk of flavivirus infection. Future studies should analyze mosquito species distribution and improve flavivirus monitoring and long-term surveillance.

Keywords:  Japanese encephalitis; flavivirus; mosquito; phylogenetic analysis; virus isolation

DOI:  https://doi.org/10.3390/microorganisms9102085
Vector Borne Zoonotic Dis. 2021 Oct 18.

Host Associations of Culex pipiens: A Two-Year Analysis of Bloodmeal Sources and Implications for Arboviral Transmission in Southeastern Virginia.

Noelle Khalil, Eliza A H Little, Karen I Akaratovic, Jay P Kiser, Charles F Abadam, Karen J Yuan, Michael J Misencik, Philip M Armstrong, Goudarz Molaei.

  Understanding vector-host interactions is crucial for evaluating the role of mosquito species in enzootic cycling and epidemic/epizootic transmission of arboviruses, as well as assessing vertebrate host contributions to maintenance and amplification in different virus foci. To investigate blood-feeding pattern of Culex pipiens, engorged mosquitoes were collected on a weekly basis at 50 sites throughout Suffolk, Virginia, using Centers for Disease Control and Prevention miniature light traps, BG-Sentinel traps, and modified Reiter gravid traps. Vertebrate hosts of mosquitoes were identified by amplifying and sequencing portions of the mitochondrial cytochrome b gene. Of 281 Cx. pipiens bloodmeals successfully identified to species, 255 (90.7%) contained solely avian blood, 13 (4.6%) mammalian, 1 (0.4%) reptilian, and 12 (4.3%) both avian and mammalian blood. Nineteen avian species were identified as hosts for Cx. pipiens with American robin (n = 141, 55.3% of avian hosts) and northern cardinal (n = 57, 22.4%) as the most common hosts. More American robin feedings took place in areas of higher development. Three mammalian species were also identified as hosts for Cx. pipiens with Virginia opossum and domestic cat as the most common hosts in this class (each n = 6, 46.2% of mammalian hosts). There was no significant seasonal difference in the proportion of bloodmeals obtained from avian hosts, but there was a decrease in the proportion of bloodmeals from mammalian hosts from spring to fall. One engorged specimen of Cx. pipiens with Virginia opossum-derived bloodmeal tested positive for West Nile virus (WNV), and another with black-and-white warbler-derived bloodmeal tested positive for eastern equine encephalitis virus. Our findings, in conjunction with the results of vector competence studies and virus isolation from field-collected mosquitoes, lend additional support that Cx. pipiens serves as the principal enzootic vector and potential epizootic/epidemic vector of WNV in southeastern Virginia.

Keywords:  Culex pipiens; Virginia; West Nile virus; bloodmeal analysis; vector

DOI:  https://doi.org/10.1089/vbz.2021.0069
Microbiol Spectr. 2021 Oct 20. e0085221

The Rare, the Best: Spread of Antimalarial-Resistant Plasmodium falciparum Parasites by Anopheles Mosquito Vectors.

Antoine Berry, Sandie Menard, Sandrine E Nsango, Luc Abate, Didier Concordet, Majoline Tchioffo Tsapi, Xavier Iriart, Parfait H Awono-Ambéné, Benjamin Roche, Isabelle Morlais.

  The emergence of resistance to antimalarials has prompted the steady switch to novel therapies for decades. Withdrawal of antimalarials, such as chloroquine in sub-Saharan Africa in the late 1990s, led to rapid declines in the prevalence of resistance markers after a few years, raising the possibility of reintroducing them for malaria treatment. Here, we provide evidence that the mosquito vector plays a crucial role in maintaining parasite genetic diversity. We followed the transmission dynamics of Plasmodium falciparum parasites through its vector in natural infections from gametocytes contained in the blood of asymptomatic volunteers until sporozoites subsequently developed in the mosquito salivary glands. We did not find any selection of the mutant or wild-type pfcrt 76 allele during development in the Anopheles mosquito vector. However, microsatellite genotyping indicated that minority genotypes were favored during transmission through the mosquito. The analysis of changes in the proportions of mutant and wild-type pfcrt 76 alleles showed that, regardless of the genotype, the less-represented allele in the gametocyte population was more abundant in mosquito salivary glands, indicating a selective advantage of the minority allele in the vector. Selection of minority genotypes in the vector would explain the persistence of drug-resistant alleles in the absence of drug pressure in areas with high malaria endemicity and high genetic diversity. Our results may have important epidemiological implications, as they predict the rapid re-emergence and spread of resistant genotypes if antimalarials that had previously selected resistant parasites are reintroduced for malaria prevention or treatment. IMPORTANCE Drug selection pressure in malaria patients is the cause of the emergence of resistant parasites. Resistance imposes a fitness cost for parasites in untreated infections, so withdrawal of the drug leads to the return of susceptible parasites. Little is known about the role of the malaria vector in this phenomenon. In an experimental study conducted in Cameroon, an area of high malaria transmission, we showed that the vector did not favor the parasites based on sensitivity or resistance criteria, but it did favor the selection of minority clones. This finding shows that the vector increases the diversity of plasmodial populations and could play an important role in falciparum malaria epidemiology by maintaining resistant clones despite the absence of therapeutic pressure.

Keywords:  Anopheles; Plasmodium falciparum; antimalarials; genetic diversity; malaria; mosquito; resistance; transmission

DOI:  https://doi.org/10.1128/Spectrum.00852-21
Emerg Infect Dis. 2021 Nov;27(11): 2952-2954

Invasive Malaria Vector Anopheles stephensi Mosquitoes in Sudan, 2016-2018.

Ayman Ahmed, Patricia Pignatelli, Arwa Elaagip, Muzamil M Abdel Hamid, Omnia Fateh Alrahman, David Weetman.

Anopheles stephensi mosquitoes are urban malaria vectors in Asia that have recently invaded the Horn of Africa. We detected emergence of An. stephensi mosquitoes in 2 noncontiguous states of eastern Sudan. Results of mitochondrial DNA sequencing suggest the possibility of distinct invasions, potentially from a neighboring country.

DOI: https://doi.org/10.3201/eid2711.210040
Pathogens. 2021 Oct 08. pii: 1294. [Epub ahead of print]10(10):

Intensive West Nile Virus Circulation in Serbia in 2018-Results of Integrated Surveillance Program.

Tamaš Petrović, Milanko Šekler, Dušan Petrić, Dejan Vidanović, Zoran Debeljak, Gospava Lazić, Diana Lupulović, Mihaela Kavran, Milena Samojlović, Aleksandra Ignjatović Ćupina, Bojana Tešović, Sava Lazić, Mišo Kolarević, Tatjana Labus, Boban Djurić.

  The results of the Serbian national integrated West Nile virus (WNV) surveillance program conducted in 2018 and funded by the Serbian Veterinary Directorate are presented. The WNV surveillance program encompassed the entire territory of Serbia and was conducted by the veterinary service in collaboration with entomologists and ornithologists. The objective of the program was early detection of WNV circulation in the environment and timely reporting to the public health service and local authorities to increase clinical and mosquito control preparedness. The program was based on the detection of WNV presence in wild birds (natural hosts) and mosquitoes (virus vectors) and on serological testing of sentinel horses (WNV-specific IgM antibodies). The season 2018 was confirmed to be the season of the most intensive WNV circulation with the highest number and severity of human cases in Serbia ever reported. The most intense WNV circulation was observed in the northern and central parts of Serbia including Vojvodina Province, the Belgrade City area, and surrounding districts, where most positive samples were detected among sentinel animals, mosquitoes and wild birds. The majority of human cases were preceded by the detection of WNV circulation during the surveillance. The WNV surveillance program in 2018 showed satisfactory results in the capacity to indicate the spatial distribution of the risk for humans and sensitivity to early detection of WNV circulation in the environment.

Keywords:  WNV national surveillance program 2018; West Nile virus; horse surveillance; mosquito surveillance; wild bird surveillance

DOI:  https://doi.org/10.3390/pathogens10101294
Genes (Basel). 2021 Oct 06. pii: 1579. [Epub ahead of print]12(10):

Genetic Diversity and Population Structure of the Asian Tiger Mosquito (Aedes albopictus) in Vietnam: Evidence for Genetic Differentiation by Climate Region.

Cuong-Van Duong, Ji-Hyoun Kang, Vinh-Van Nguyen, Yeon-Jae Bae.

  Aedes albopictus is a native mosquito to Southeast Asia with a high potential for disease transmission. Understanding how Ae. albopictus populations that develop in the species' native range is useful for planning future control strategies and for identifying the sources of invasive ranges. The present study aims to investigate the genetic diversity and population structure of Ae. albopictus across various climatic regions of Vietnam. We analyzed mitochondrial cytochrome oxidase I (COI) gene sequences from specimens collected from 16 localities, and we used distance-based redundancy analysis to evaluate the amount of variation in the genetic distance that could be explained by both geographic distance and climatic factors. High levels of genetic polymorphism were detected, and the haplotypes were similar to those sequences from both temperate and tropical regions worldwide. Of note, these haplotype groups were geographically distributed, resulting in a distinct population structure in which northeastern populations and the remaining populations were genetically differentiated. Notably, genetic variation among the Ae. albopictus populations was driven primarily by climatic factors (64.55%) and to a lesser extent was also influenced by geographic distance (33.73%). These findings fill important gaps in the current understanding of the population genetics of Ae. albopictus in Vietnam, especially with respect to providing data to track the origin of the invaded regions worldwide.

Keywords:  Aedes albopictus; Vietnam; genetic diversity; mitochondrial DNA; population structure

DOI:  https://doi.org/10.3390/genes12101579
Trends Parasitol. 2021 Oct 18. pii: S1471-4922(21)00237-3. [Epub ahead of print]

Human attractive cues and mosquito host-seeking behavior.

Iliano V Coutinho-Abreu, Jeffrey A Riffell, Omar S Akbari.

  Female mosquitoes use chemical and physical cues, including vision, smell, heat, and humidity, to orient toward hosts. Body odors are produced by skin resident bacteria that convert metabolites secreted in sweat into odorants that confer the characteristic body scent. Mosquitoes detect these compounds using olfactory receptors in their antennal olfactory receptor neurons. Such information is further integrated with the senses of temperature and humidity, as well as vision, processed in the brain into a behavioral output, leading to host finding. Knowledge of human scent components unveils a variety of odorants that are attractive to mosquitoes, but also odor-triggering repellency. Finding ways to divert human-seeking behavior by female mosquitoes using odorants can possibly mitigate mosquito-borne pathogen transmission.

Keywords:  behavior; host-seeking; microbiota; mosquito; odorant receptors; olfaction

DOI:  https://doi.org/10.1016/j.pt.2021.09.012
Pathogens. 2021 Oct 15. pii: 1334. [Epub ahead of print]10(10):

Distribution and Molecular Identification of Culex pipiens and Culex tritaeniorhynchus as Potential Vectors of Rift Valley Fever Virus in Jazan, Saudi Arabia.

Saleh Eifan, Atif Hanif, Islam Nour, Sultan Alqahtani, Zaki M Eisa, Ommer Dafalla, Alain Kohl.

  Entomologic investigations were conducted in the Al-Darb, Al-Reath, Al-Aridah, Abuareesh, Al-Ahad, Samttah, Sabyah, Damad and Beash areas by CO2-baited CDC miniature light traps in the Jazan region. Vectors were identified morphologically, as well as COI gene segment amplification and sequencing. The relative abundance (RA%) and pattern of occurrence (C%) were recorded. The presence of the Rift Valley fever virus (RVFV) in pooled mosquito samples was investigated by reverse transcriptase-polymerase chain reaction (RT-PCR). Culex pipiens (C. pipiens) and Culex tritaeniorhynchus (C. tritaeniorhynchus) were found with RA% values of 96% and 4%, respectively, in the region. Significant variations in vector population densities were observed in different districts. The C. pipiens was found highly abundant in all districts and RA% value (100%) was recorded in the Al-Darb, Al-Reath, Al-Aridah, Samttah and Damad areas, whereas RA% values (93.75%, 93.33%, 92.30% and 91.66%) were noted in Al-Ahad, Sabyah, Abuareesh and Beash districts, respectively. RA% values for C. tritaeniorhynchus were recorded as 8.33%, 7.70%, 6.66% and 6.25% in Beash, Abuareesh, Sabyah and Al-Ahad areas, respectively. The pattern of occurrence for C. pipiens and C. tritaeniorhynchus was recorded as 100% and 44.4% in the region. Phylogenetic analysis of C. pipiens and C. tritaeniorhynchus exhibited a close relationship with mosquitoes from Kenya and Turkey, respectively. All mosquito samples tested by RT-PCR were found negative for RVFV. In summary, the current study assessed the composition, abundance, distribution of different mosquito vectors and presence of RVFV in different areas of the Jazan region. Our data will help risk assessments of RVFV future re-emergence in the region.

Keywords:  C. pipiens; C. tritaeniorhynchus; Jazan; Rift Valley fever virus; abundance

DOI:  https://doi.org/10.3390/pathogens10101334
BMC Infect Dis. 2021 Oct 19. 21(1): 1078

Global dengue importation: a systematic review.

Xiao Wei Sylvia Gwee, Pearleen Ee Yong Chua, Junxiong Pang.

   BACKGROUND: Importation of dengue following globalization presents an emerging threat to global health. However, evidence on global geographical sources and the potential of dengue importation globally are lacking. This study aims to systematically review the sources of dengue importation globally and the risk of dengue outbreaks globally.
METHODS: This systematic review was conducted in accordance to Cochrane's PRISMA guidelines. Articles published through 31 December 2019 with laboratory-confirmed dengue imported cases were consolidated from PubMed, EMBASE and Scopus. Sources of dengue importation reported worldwide were analysed by country and geographical regions. Sources of dengue importation into United States of America and Europe specifically were also analysed.
RESULTS: A total of 3762 articles were found. Among which, 210 articles-documenting 14,972 imported dengue cases with reported sources-were eligible. 76.3% of imported cases worldwide were from Asia. 15.7%, 5.6%, 2.0% and 0.1% were imported from the Americas, Africa, Oceania and Europe regions respectively. Imported dengue cases in the U.S. were from Americas (55.3%), Asia (34.7%), Africa (6.7%) and Oceania (3.3%). Imported dengue cases in Europe were from Asia (66.0%), Americas (21.9%), Africa (10.8%) and Oceania (1.1%).
CONCLUSION: The potential of dengue outbreaks occurring globally, especially among non-endemic regions with dengue-susceptible populations is high. With the expansion of Aedes mosquito population globally due to global warming and globalisation, dengue importation constitutes an emerging global health security threat.

Keywords:  Dengue; Global health; Importation; Outbreak; Public health

DOI:  https://doi.org/10.1186/s12879-021-06740-1
J Med Entomol. 2021 Oct 18. pii: tjab160. [Epub ahead of print]

Improving the DNA Barcode Library of Mosquito Species With New Identifications and Discoveries in North-Central Argentina.

M Laurito, A M Ayala, D L Arias-Builes, W R Almirón.

  The family Culicidae is represented by 244 species in Argentina, many of them with epidemiological importance. DNA barcodes are effective tools for identifying mosquito species, for knowing genetic variability, and for establishing phylogenetic relationships. This work aims to explore mosquito diversity employing different species delimitation approaches and to establish formally a DNA barcode library for the Argentinian mosquito fauna. Barcode fragments of 80 specimens of Argentinian mosquitoes of 28 species of the genera Aedeomyia Theobald (Diptera: Culicidae), Anopheles Meigen (Diptera: Culicidae), Coquillettidia Dyar (Diptera: Culicidae), Culex L. (Diptera: Culicidae), Haemagogus Williston (Diptera: Culicidae), Mansonia Blanchard (Diptera: Culicidae), Nyssorhynchus Blanchard (Diptera: Culicidae), Ochlerotatus Lynch-Arribálzaga (Diptera: Culicidae), Psorophora Robinneau-Desvoidy (Diptera: Culicidae) and Uranotaenia Lynch-Arribálzaga (Diptera: Culicidae) were sequenced. Another 82 sequences were obtained from public databases to establish the phylogenetic relationships using Maximum Likelihood and Bayesian Inference, and the species boundaries based on three approaches (ABGD, GMYC, and mPTP). Sixteen of the 28 species sequenced were recovered as monophyletic, of which 12 were also recognized as molecular operational taxonomic units according to the three methodologies. The disparity between morphology and barcode-based identifications could be explained by synonymy, species complexes occurrence, hybridization, incomplete lineage sorting, or the effect of the geographical scale of sampling. Twenty of the 28 sequenced species are new barcodes for Argentina and 11 are the first for science. This increases from 31 to 52 (12.7 to 21.31%) and from six to 10 (28.57 to 47.62%) the number of species and genera, respectively, with barcode sequences in Argentina. New species records are provided.

Keywords:  COI; diversity; species boundary; taxonomy

DOI:  https://doi.org/10.1093/jme/tjab160
Animals (Basel). 2021 Oct 13. pii: 2951. [Epub ahead of print]11(10):

Spatiotemporal Analysis of West Nile Virus Epidemic in South Banat District, Serbia, 2017-2019.

Sonja Radojicic, Aleksandar Zivulj, Tamas Petrovic, Jakov Nisavic, Vesna Milicevic, Sandra Sipetic-Grujicic, Dusan Misic, Malgorzata Korzeniowska, Slavoljub Stanojevic.

  West Nile virus (WNV) is an arthropod-born pathogen, which is transmitted from wild birds through mosquitoes to humans and animals. At the end of the 20th century, the first West Nile fever (WNF) outbreaks among humans in urban environments in Eastern Europe and the United States were reported. The disease continued to spread to other parts of the continents. In Serbia, the largest number of WNV-infected people was recorded in 2018. This research used spatial statistics to identify clusters of WNV infection in humans and animals in South Banat County, Serbia. The occurrence of WNV infection and risk factors were analyzed using a negative binomial regression model. Our research indicated that climatic factors were the main determinant of WNV distribution and were predictors of endemicity. Precipitation and water levels of rivers had an important influence on mosquito abundance and affected the habitats of wild birds, which are important for maintaining the virus in nature. We found that the maximum temperature of the warmest part of the year and the annual temperature range; and hydrographic variables, e.g., the presence of rivers and water streams were the best environmental predictors of WNF outbreaks in South Banat County.

Keywords:  GIS; West Nile virus; mosquitoes; sentinel animals; spatial analysis

DOI:  https://doi.org/10.3390/ani11102951
Front Public Health. 2021 ;9 715759

Emerging and Re-emerging Vector-Borne Infectious Diseases and the Challenges for Control: A Review.

Bayissa Chala, Feyissa Hamde.

  Vector-borne emerging and re-emerging diseases pose considerable public health problem worldwide. Some of these diseases are emerging and/or re-emerging at increasing rates and appeared in new regions in the past two decades. Studies emphasized that the interactions among pathogens, hosts, and the environment play a key role for the emergence or re-emergence of these diseases. Furthermore, social and demographic factors such as human population growth, urbanization, globalization, trade exchange and travel and close interactions with livestock have significantly been linked with the emergence and/or re-emergence of vector-borne diseases. Other studies emphasize the ongoing evolution of pathogens, proliferation of reservoir populations, and antimicrobial drug use to be the principal exacerbating forces for emergence and re-emergence of vector-borne infectious diseases. Still other studies equivocally claim that climate change has been associated with appearance and resurgence of vector-borne infectious diseases. Despite the fact that many important emerging and re-emerging vector-borne infectious diseases are becoming better controlled, our success in stopping the many new appearing and resurging vector-borne infectious diseases that may happen in the future seems to be uncertain. Hence, this paper reviews and synthesizes the existing literature to explore global patterns of emerging and re-emerging vector-borne infections and the challenges for their control. It also attempts to give insights to the epidemiological profile of major vector-borne diseases including Zika fever, dengue, West Nile fever, Crimean-Congo hemorrhagic fever, Chikungunya, Yellow fever, and Rift Valley fever.

Keywords:  climate change; emerging infectious diseases; re-emerging infectious diseases; vector-borne infectious diseases; zoonotic diseases

DOI:  https://doi.org/10.3389/fpubh.2021.715759
J Med Virol. 2021 Oct 19.

Detection of Saint Louis Encephalitis virus in two Brazilian States.

Marília Mazzi Moraes, Janaina Rigotti Kubiszeski, Carla Júlia da Silva Pessoa Vieira, Arianne Fagotti Gusmao, Taina Silva Pratis, Tatiana Elias Colombo, Sirlei Franck Thies, Fabiana do Carmo Araujo, Cleslei Fernando Zanelli, Bruno Henrique Gonçalves de Aguiar Milhim, Gislaine Celestino Dutra da Silva, Maurício Lacerda Nogueira, Carolina Colombelli Pacca, Roberta Vieira de Morais Bronzoni, Adriano Mondini.

  We describe the circulation of Saint Louis encephalitis virus (SLEV) in two Brazilian States during outbreaks of Dengue and Zika viruses. We detected the virus in patients from Araraquara, State of São Paulo, and in patients and mosquitoes Culex quinquefasciatus from Sinop, State of Mato Grosso. Phylogenetic analysis grouped our samples within genotype V, which are closely related to other strains. This genotype was previously detected in other parts of the country and seems to have established circulation in Brazil. This article is protected by copyright. All rights reserved.

Keywords:  Arbovirus; Brazil; Saint Louis Encephalitis virus; dengue; phylogenetic analysis; viral surveillance

DOI:  https://doi.org/10.1002/jmv.27402