bims-mosdis 2021-08-29 papers

bims-mosdis

Biomed News

on Mosquito distribution and disease

Issue of 2021–08–29
twenty-one papers selected by
Richard Halfpenny, Staffordshire University

Emerging Mosquito-Borne Viruses Linked to Aedes aegypti and Aedes albopictus: Global Status and Preventive Strategies.
Mosquitoes Know No Borders: Surveillance of Potential Introduction of Aedes Species in Southern Québec, Canada.
Zika Virus Potential Vectors among Aedes Mosquitoes from Hokkaido, Northern Japan: Implications for Potential Emergence of Zika Disease.
Uncovering the Worldwide Diversity and Evolution of the Virome of the Mosquitoes Aedes aegypti and Aedes albopictus.
Diversity, distribution and relative abundance of the mosquito fauna (Diptera: Culicidae) of Malakand and Dir Lower, Pakistan.
Dirofilaria immitis and Dirofilaria repens in mosquitoes from Corsica Island, France.
Impact of cattle on the abundance of indoor and outdoor resting malaria vectors in southern Malawi.
Entomological baseline data collection and power analyses in preparation of a mosquito swarm-killing intervention in south-western Burkina Faso.
Predatory and competitive interaction in Anopheles gambiae sensu lato larval breeding habitats in selected villages of central Uganda.
Microorganisms Associated with Mosquito Oviposition Sites: Implications for Habitat Selection and Insect Life Histories.
Rapid evolution of knockdown resistance haplotypes in response to pyrethroid selection in Aedes aegypti.
Fish-Released Kairomones Affect Mosquito Oviposition and Larval Life History.
Pyrethroid Resistance in Anopheles gambiae Not Associated with Insecticide-Treated Mosquito Net Effectiveness Across Sub-Saharan Africa.
Evolution of Adaptive Variation in the Mosquito Culex pipiens: Multiple Independent Origins of Insecticide Resistance Mutations.
The global emergence of Chikungunya infection: An integrated view.
Evaluation of Total Female and Male Aedes aegypti Proteomes Reveals Significant Predictive Protein-Protein Interactions, Functional Ontologies, and Differentially Abundant Proteins.
Mosquito-Borne Viral Pathogens Detected in Zambia: A Systematic Review.
West Nile Virus in the State of Ceará, Northeast Brazil.
Yellow Fever Outbreak in Eastern Senegal, 2020-2021.
Serological Evidence of Widespread Zika Transmission across the Philippines.
A Cluster of Dengue Cases in Travelers: A Clinical Series from Thailand.

Vector Borne Zoonotic Dis. 2021 Aug 23.

Emerging Mosquito-Borne Viruses Linked to Aedes aegypti and Aedes albopictus: Global Status and Preventive Strategies.

Jonas Näslund, Clas Ahlm, Koushikul Islam, Magnus Evander, Göran Bucht, Olivia Wesula Lwande.

  Emerging mosquito-borne viruses continue to cause serious health problems and economic burden among billions of people living in and near the tropical belt of the world. The highly invasive mosquito species Aedes aegypti and Aedes albopictus have successively invaded and expanded their presence as key vectors of Chikungunya virus, dengue virus, yellow fever virus, and Zika virus, and that has consecutively led to frequent outbreaks of the corresponding viral diseases. Of note, these two mosquito species have gradually adapted to the changing weather and environmental conditions leading to a shift in the epidemiology of the viral diseases, and facilitated their establishment in new ecozones inhabited by immunologically naive human populations. Many abilities of Ae. aegypti and Ae. albopictus, as vectors of significant arbovirus pathogens, may affect the infection and transmission rates after a bloodmeal, and may influence the vector competence for either virus. We highlight that many collaborating risk factors, for example, the global transportation systems may result in sporadic and more local outbreaks caused by mosquito-borne viruses related to Ae. aegypti and/or Ae. albopictus. Those local outbreaks could in synergy grow and produce larger epidemics with pandemic characters. There is an urgent need for improved surveillance of vector populations, human cases, and reliable prediction models. In summary, we recommend new and innovative strategies for the prevention of these types of infections.

Keywords:  Aedes; arboviruses; vector control; vectorial capacity and pandemic

DOI:  https://doi.org/10.1089/vbz.2020.2762
Pathogens. 2021 Aug 07. pii: 998. [Epub ahead of print]10(8):

Mosquitoes Know No Borders: Surveillance of Potential Introduction of Aedes Species in Southern Québec, Canada.

Anne-Marie Lowe, Karl Forest-Bérard, Richard Trudel, Ernest Lo, Philippe Gamache, Matthieu Tandonnet, Serge-Olivier Kotchi, Patrick Leighton, Antonia Dibernardo, Robbin Lindsay, Antoinette Ludwig.

  Current climatic conditions limit the distribution of Aedes (Stegomyia) albopictus (Skuse, Diptera: Culicidae) in the north, but predictive climate models suggest this species could establish itself in southern Canada by 2040. A vector of chikungunya, dengue, yellow fever, Zika and West Nile viruses, the Ae. Albopictus has been detected in Windsor, Ontario since 2016. Given the potential public health implications, and knowing that Aedes spp. can easily be introduced by ground transportation, this study aimed to determine if specimens could be detected, using an adequate methodology, in southern Québec. Mosquitoes were sampled in 2016 and 2017 along the main roads connecting Canada and the U.S., using Biogent traps (Sentinel-2, Gravide Aedes traps) and ovitraps. Overall, 24 mosquito spp. were captured, excluding Ae. Albopictus, but detecting one Aedes (Stegomyia) aegypti (Skuse) specimen (laid eggs). The most frequent species among captured adults were Ochlerotatus triseriatus, Culex pipiens complex, and Ochlerotatus japonicus (31.0%, 26.0%, and 17.3%, respectively). The present study adds to the increasing number of studies reporting on the range expansions of these mosquito species, and suggests that ongoing monitoring, using multiple capture techniques targeting a wide range of species, may provide useful information to public health with respect to the growing risk of emerging mosquito-borne diseases in southern Canada.

Keywords:  Aedes aegypti; Aedes albopictus; Ochlerotatus japonicus; Ochlerotatus triseriatus; invasive mosquito species; public health

DOI:  https://doi.org/10.3390/pathogens10080998
Pathogens. 2021 Jul 24. pii: 938. [Epub ahead of print]10(8):

Zika Virus Potential Vectors among Aedes Mosquitoes from Hokkaido, Northern Japan: Implications for Potential Emergence of Zika Disease.

Leo Uchida, Miki Shibuya, Ronald Enrique Morales-Vargas, Katsuro Hagiwara, Yasukazu Muramatsu.

  The Zika virus (ZIKV) is a rapidly expanding mosquito-borne virus that causes febrile illness in humans. Aedes aegypti and Ae. albopictus are the primary ZIKV vectors; however, the potential vector competence of other Aedes mosquitoes distributed in northern Japan (Palearctic ecozone) are not yet known. In this study, the susceptibility to Zika virus infection of three Aedes mosquitoes distributed in the main city of the northern Japan and their capacities as vectors for ZIKV were evaluated. Field-collected mosquitoes were fed ad libitum an infectious blood meal containing the ZIKV PRVABC59. The Zika virus was detected in the abdomen of Ae. galloisi and Ae. japonicus at 2-10 days post infection (PI), and from the thorax and head of Ae. galloisi at 10 days PI, resulting in 17.6% and 5.9% infection rates, respectively. The Zika virus was not detected from Ae. punctor at any time. Some northern Japanese Aedes could be suspected as vectors of ZIKV but the risk may be low when compared with major ZIKV vectors.

Keywords:  Aedes galloisi; Aedes japonicus; Aedes mosquitoes; Palearctic ecozone; Zika virus; susceptibility

DOI:  https://doi.org/10.3390/pathogens10080938
Microorganisms. 2021 Aug 03. pii: 1653. [Epub ahead of print]9(8):

Uncovering the Worldwide Diversity and Evolution of the Virome of the Mosquitoes Aedes aegypti and Aedes albopictus.

Rhys Parry, Maddie E James, Sassan Asgari.

  Aedes aegypti, the yellow fever mosquito, and Aedes albopictus, the Asian tiger mosquito, are the most significant vectors of dengue, Zika, and Chikungunya viruses globally. Studies examining host factors that control arbovirus transmission demonstrate that insect-specific viruses (ISVs) can modulate mosquitoes' susceptibility to arbovirus infection in both in vivo and in vitro co-infection models. While research is ongoing to implicate individual ISVs as proviral or antiviral factors, we have a limited understanding of the composition and diversity of the Aedes virome. To address this gap, we used a meta-analysis approach to uncover virome diversity by analysing ~3000 available RNA sequencing libraries representing a worldwide geographic range for both mosquitoes. We identified ten novel viruses and previously characterised viruses, including mononegaviruses, orthomyxoviruses, negeviruses, and a novel bi-segmented negev-like group. Phylogenetic analysis suggests close relatedness to mosquito viruses implying likely insect host range except for one arbovirus, the multi-segmented Jingmen tick virus (Flaviviridae) in an Italian colony of Ae. albopictus. Individual mosquito transcriptomes revealed remarkable inter-host variation of ISVs within individuals from the same colony and heterogeneity between different laboratory strains. Additionally, we identified striking virus diversity in Wolbachia infected Aedes cell lines. This study expands our understanding of the virome of these important vectors. It provides a resource for further assessing the ecology, evolution, and interaction of ISVs with their mosquito hosts and the arboviruses they transmit.

Keywords:  Aedes aegypti; Aedes albopictus; ISV; Jingmen tick virus; Wolbachia; insect viruses; virome

DOI:  https://doi.org/10.3390/microorganisms9081653
Braz J Biol. 2021 ;pii: S1519-69842023000100170. [Epub ahead of print]83 e247374

Diversity, distribution and relative abundance of the mosquito fauna (Diptera: Culicidae) of Malakand and Dir Lower, Pakistan.

M Attaullah, S Gul, D Bibi, A Andaleeb, I Ilahi, M Siraj, M Ahmad, I Ullah, M Ali, S Ahmad, Z Ullah.

The present study was conducted to evaluate the diversity, distribution (C) and relative abundance (RA) of the mosquito fauna (Diptera: Culicidae) of Malakand and Dir Lower, Pakistan. Collection of specimens (n = 1087) was made during September 2018 to July 2019 at six different habitats including freshwater bodies, rice fields, animal sheds, indoors, drains and sewage waters. Specimens were collected through light traps, pyrethrum spray, aspirators and nets and subsequently killed, preserved and then arranged in entomological boxes for identification. Three genera were identified namely Culex, Anopheles and Aedes. A total of fourteen species were identified namely: Cx. quinquefasciatus (Say, 1823), An. stephensi (Liston, 1901), Cx. tritaeniorhynchus (Giles, 1901), Ae. vittatus (Bigot, 1861), An. maculatus (Theobald, 1901), An. fluviatilis (James, 1902), Cx. vishnui (Theobald, 1901), Ae. aegypti (Linnaeus, 1762) An. subpictus (Grassi, 1899), An. dthali (Patton, 1905), An. culicifascies (Giles, 1901), An. pallidus (Theobald, 1901), Ae. albopictus (Skuse, 1894) and An. annularis (van der Wulp, 1884). Cx. quinquefasciatus was found constantly distributed in the study area with RA = 16.5% and C = 100%. An. annularis was found as a satellite species, sporadically distributed in the study area having RA = 0.9% and C = 17%. Diversity indices of mosquitoes in the studied habitats were found as, Shannon-Wiener Index (2.415), Simpson Index (9.919), Fisher's Index (2.269) and Margalef's Index (1.859). A statistically significant difference was recorded in mosquito diversity in the six habitats (Kruskal-Wallis, chi-squared, H = 17.5, df = 5, P = 0.003 at α = 0.05). The present study encompasses mosquito fauna of Malakand, Pakistan with respect to diversity, relative abundance and distribution in diverse habitats and all seasons of the year. This will assist scientists working in various fields related with epidemiology, medical and veterinary entomology, ecology and allied areas of biological sciences.

DOI: https://doi.org/10.1590/1519-6984.247374
Parasit Vectors. 2021 Aug 26. 14(1): 427

Dirofilaria immitis and Dirofilaria repens in mosquitoes from Corsica Island, France.

Laidoudi Younes, Hélène Barré-Cardi, Samia Bedjaoui, Nazli Ayhan, Marie Varloud, Oleg Mediannikov, Domenico Otranto, Bernard Davoust.

   BACKGROUND: Dirofilaria immitis and Dirofilaria repens are the main causative agents of heartworm disease and subcutaneous dirofilariasis in domestic and wild canids, respectively. Both pathogens have zoonotic potential and are transmitted by mosquitoes. The present study aimed to determine the transmission period, prevalence and diversity of Dirofilaria spp. vectors from endemic areas of Corsica (France).
METHODS: A monthly point data model based on average temperature recorded by four meteorological stations during 2017 was used to calculate the Dirofilaria transmission period. From June to September 2017, female mosquitoes (n = 1802) were captured using Biogents® Sentinel 2 traps lured with carbon dioxide and BG-Lure™ or octanol. Mosquitoes were identified to species level, pooled accordingly, and screened using multiplex real-time qPCR to detect D. immitis and D. repens.
RESULTS: The monthly point data model showed the possible transmission of Dirofilaria spp. from the third week in May to the last week in October in the studied area. Mosquitoes were identified as Ochlerotatus caspius (n = 1432), Aedes albopictus (n = 199), Culex pipiens sensu lato (n = 165) and Aedes vexans (n = 6) and were grouped into 109 pools (from 1 to 27 specimens, mean 11.4 ± 0.7), of which 16 scored positive for Dirofilaria spp. (i.e., n = 13; estimated infection rate [EIR] = 1.1% for D. immitis and n = 3; EIR = 0.2% for D. repens). Specifically, 6 (i.e., EIR = 3.8%) of 15 pools of Ae. albopictus were positive for D. immitis, 2 of 14 of Cx. pipiens s.l. were positive for D. immitis and D. repens, respectively, and 8 of 77 pools of Oc. caspius were positive for D. immitis (i.e., n = 6; EIR = 0.4%) and D. repens (i.e., 2; EIR = 0.1%). The highest mosquito infection rate was recorded in July (EIR = 2.5%), then in June (EIR = 1.3%) and September (EIR = 0.6%).
CONCLUSIONS: The data suggest that both Dirofilaria species are endemic and occur possibly in sympatry in the studied area in Corsica, highlighting the need to implement preventive chemoprophylaxis and vector control strategies to reduce the risk of these filarioids in dog and human populations.

Keywords:  Corsica; Dirofilaria immitis; Dirofilaria repens; Mosquitoes; Transmission suitability

DOI:  https://doi.org/10.1186/s13071-021-04931-y
Malar J. 2021 Aug 26. 20(1): 353

Impact of cattle on the abundance of indoor and outdoor resting malaria vectors in southern Malawi.

Monicah M Mburu, Kennedy Zembere, Themba Mzilahowa, Anja D Terlouw, Tumaini Malenga, Henk van den Berg, Willem Takken, Robert S McCann.

   BACKGROUND: Understanding the blood feeding preferences and resting habits of malaria vectors is important for assessing and designing effective malaria vector control tools. The presence of livestock, such as cattle, which are used as blood meal hosts by some malaria vectors, may impact malaria parasite transmission dynamics. The presence of livestock may provide sufficient blood meals for the vectors, thereby reducing the frequency of vectors biting humans. Alternatively, the presence of cattle may enhance the availability of blood meals such that infectious mosquitoes may survive longer, thereby increasing the risk of malaria transmission. This study assessed the effect of household-level cattle presence and distribution on the abundance of indoor and outdoor resting malaria vectors.
METHODS: Houses with and without cattle were selected in Chikwawa district, southern Malawi for sampling resting malaria vectors. Prokopack aspirators and clay pots were used for indoor and outdoor sampling, respectively. Each house was sampled over two consecutive days. For houses with cattle nearby, the number of cattle and the distances from the house to where the cattle were corralled the previous night were recorded. All data were analysed using generalized linear models fitted with Poisson distribution.
RESULTS: The malaria vectors caught resting indoors were Anopheles gambiae sensu stricto (s.s.), Anopheles arabiensis and Anopheles funestus s.s. Outdoor collections consisted primarily of An. arabiensis. The catch sizes of indoor resting An. gambiae sensu lato (s.l.) were not different in houses with and without cattle (P = 0.34). The presence of cattle near a house was associated with a reduction in the abundance of indoor resting An. funestus s.l. (P = 0.04). This effect was strongest when cattle were kept overnight ≤ 15 m away from the houses (P = 0.03). The blood meal hosts varied across the species.
CONCLUSION: These results highlight differences between malaria vector species and their interactions with potential blood meal hosts, which may have implications for malaria risk. Whereas An. arabiensis remained unaffected, the reduction of An. funestus s.s. in houses near cattle suggests a potential protective effect of cattle. However, the low abundance of mosquitoes reduced the power of some analyses and limited the generalizability of the results to other settings. Therefore, further studies incorporating the vectors' host-seeking behaviour/human biting rates are recommended to fully support the primary finding.

Keywords:  Anophelines; Blood-meal hosts; Cattle; Indoors; Outdoors; Resting; Zooprophylaxis

DOI:  https://doi.org/10.1186/s12936-021-03885-x
Malar J. 2021 Aug 23. 20(1): 346

Entomological baseline data collection and power analyses in preparation of a mosquito swarm-killing intervention in south-western Burkina Faso.

Abdoulaye Niang, Simon P Sawadogo, Abdoul A Millogo, Nwamaka O Akpodiete, Roch K Dabiré, Frederic Tripet, Abdoulaye Diabaté.

   BACKGROUND: Insecticides are currently the main tools used to reduce the transmission of malaria; therefore, the development of resistance to insecticides in malaria vectors is of major concern for malaria control. The resistance level to pyrethroids is particularly high in the Western region of Burkina Faso and may affect the efficacy of insecticidal bed nets and indoor residual spraying. Adult mosquito swarming and other nocturnal behaviours exhibit spatial and temporal patterns that suggest potential vulnerability to targeted space spraying with effective insecticides. Indeed, targeted space-spraying against adult mosquito swarms has been used to crash mosquito populations and disrupt malaria transmission.
METHODS: Prior to impact assessment of swarm killing, a baseline data collection was conducted from June to November 2016 in 10 villages divided into two areas in western Burkina Faso. The data considered both ecological and demographic characteristics to monitor the key entomological parameters.
RESULTS: The mean number of swarms observed was 35 per village, ranging from 25 to 70 swarms according to the village. Female density in both areas varied significantly as a function of the village and the period of collection. The human biting rate was significantly affected by the period of collection and depended upon whether the collection was carried out indoors or outdoors. Averages of parity rate were high in both areas for all periods of collection, ranging from 60 to 90%. These values ranged from 80 to 100% for inseminated females. Sporozoite rates ranged between 1.6 and 7.2% depending upon the village. The molecular identification of resting and swarming mosquitoes showed the presence of the three major malaria vectors in Burkina Faso, but in different proportions for each village.
CONCLUSIONS: The distribution of the potential swarm markers and swarms in villages suggested that swarms are clustered across space, making intervention easier. Power simulations showed that the direct sampling of swarms provides the highest statistical power, thereby reducing the number of villages needed for a trial.

Keywords:  Baseline data; Burkina Faso; Malaria vector control; Power analyses; Swarm-killing intervention

DOI:  https://doi.org/10.1186/s12936-021-03877-x
Parasit Vectors. 2021 Aug 21. 14(1): 420

Predatory and competitive interaction in Anopheles gambiae sensu lato larval breeding habitats in selected villages of central Uganda.

Hudson Onen, Robinson Odong, Moses Chemurot, Frédéric Tripet, Jonathan K Kayondo.

   BACKGROUND: Malaria is often persistent in communities surrounded by mosquito breeding habitats. Anopheles gambiae sensu lato exploit a variety of aquatic habitats, but the biotic determinants of its preferences are poorly understood. This study aimed to identify and quantify macroinvertebrates in different habitat types with determined water physico-chemical parameters to establish those preferred by An. gambiae s.l. larvae as well as their predators and competitors.
METHODS: A field survey was conducted in Kibuye and Kayonjo villages located in the vicinity of the River Sezibwa, north-eastern Uganda to identify Anopheline larval habitats shared by aquatic insects. Habitats were geo-recorded and as streams, ponds, temporary pools and roadside ditches. From October to December 2017, random microhabitats/quadrats were selected from each habitat type, their water physico-chemical parameters (electrical conductivity, total dissolved solids, temperature and pH) were measured, and they were sampled for macroinvertebrates using standard dippers. All collected arthropod macroinvertebrates were then morphologically identified to family level and enumerated.
RESULTS: Principal component analysis showed that the four larval habitat types were characterized by distinct physico-chemical parameter profiles. Ponds and streams had the highest number and diversity of macroinvertebrate insect taxa and sustained few An. gambiae s.l. larvae. Anopheles gambiae s.l. were more common in roadside ditches and particularly abundant in temporary pools which it commonly shared with Dytiscidae (predaceous diving beetles) and Culex spp. Cluster correlation analysis conducted on the abundance of these taxa within quadrats suggested that An. gambiae s.l. and Dytiscidae have the most similar patterns of microhabitat use, followed by Cybaeidae (water spiders). Whilst Culex spp. co-occurred with An. gambiae s.l. in some habitats, there was only partial niche overlap and no clear evidence of competition between the two mosquito taxa.
CONCLUSIONS: Ponds and streams are habitats that host the largest diversity and abundance of aquatic insect taxa. Anopheles gambiae s.l. larvae distinctively preferred temporary pools and roadside ditches, where they were exposed to few predators and no apparent competition by Culex spp. Further studies should aim to test the impact of Dytiscidae and Cybaeidae on An. gambiae s.l. dynamics experimentally.

Keywords:  An. gambiae s.l. competition; Aquatic insects; Habitat types; Macroinvertebrates; Niche overlap; Predation

DOI:  https://doi.org/10.1186/s13071-021-04926-9
Microorganisms. 2021 Jul 26. pii: 1589. [Epub ahead of print]9(8):

Microorganisms Associated with Mosquito Oviposition Sites: Implications for Habitat Selection and Insect Life Histories.

Maxime Girard, Edwige Martin, Laurent Vallon, Vincent Raquin, Christophe Bellet, Yves Rozier, Emmanuel Desouhant, Anne-Emmanuelle Hay, Patricia Luis, Claire Valiente Moro, Guillaume Minard.

  Mosquitoes are considered one of the most important threats worldwide due to their ability to vector pathogens. They are responsible for the transmission of major pathogens such as malaria, dengue, zika, or chikungunya. Due to the lack of treatments or prophylaxis against many of the transmitted pathogens and an increasing prevalence of mosquito resistance to insecticides and drugs available, alternative strategies are now being explored. Some of these involve the use of microorganisms as promising agent to limit the fitness of mosquitoes, attract or repel them, and decrease the replication and transmission of pathogenic agents. In recent years, the importance of microorganisms colonizing the habitat of mosquitoes has particularly been investigated since they appeared to play major roles in their development and diseases transmission. In this issue, we will synthesize researches investigating how microorganisms present within water habitats may influence breeding site selection and oviposition strategies of gravid mosquito females. We will also highlight the impact of such microbes on the fate of females' progeny during their immature stages with a specific focus on egg hatching, development rate, and larvae or pupae survival.

Keywords:  behavior; development; larval habitat; life history traits; microbiome; microbiota; mosquitoes; nutrition; oviposition; survival

DOI:  https://doi.org/10.3390/microorganisms9081589
Evol Appl. 2021 Aug;14(8): 2098-2113

Rapid evolution of knockdown resistance haplotypes in response to pyrethroid selection in Aedes aegypti.

Jennifer Baltzegar, Michael Vella, Christian Gunning, Gissella Vasquez, Helvio Astete, Fred Stell, Michael Fisher, Thomas W Scott, Audrey Lenhart, Alun L Lloyd, Amy Morrison, Fred Gould.

  This study describes the evolution of knockdown resistance (kdr) haplotypes in Aedes aegypti in response to pyrethroid insecticide use over the course of 18 years in Iquitos, Peru. Based on the duration and intensiveness of sampling (~10,000 samples), this is the most thorough study of kdr population genetics in Ae. aegypti to date within a city. We provide evidence for the direct connection between programmatic citywide pyrethroid spraying and the increase in frequency of specific kdr haplotypes by identifying two evolutionary events in the population. The relatively high selection coefficients, even under infrequent insecticide pressure, emphasize how quickly Ae. aegypti populations can evolve. In our examination of the literature on mosquitoes and other insect pests, we could find no cases where a pest evolved so quickly to so few exposures to low or nonresidual insecticide applications. The observed rapid increase in frequency of resistance alleles might have been aided by the incomplete dominance of resistance-conferring alleles over corresponding susceptibility alleles. In addition to dramatic temporal shifts, spatial suppression experiments reveal that genetic heterogeneity existed not only at the citywide scale, but also on a very fine scale within the city.

Keywords:  Aedes aegypti; dominance; insecticide resistance; kdr; knockdown resistance; selection

DOI:  https://doi.org/10.1111/eva.13269
J Med Entomol. 2021 Aug 25. pii: tjab145. [Epub ahead of print]

Fish-Released Kairomones Affect Mosquito Oviposition and Larval Life History.

Alon Silberbush.

  Several species of mosquitoes respond to the presence of kairomones released by larvivorous predators during oviposition habitat selection and larval development. These responses may differ among mosquito species and do not always correlate with larval survival. This study examined the responses of the mosquito Culiseta longiareolata Macquart (Diptera: Culicidae) to kairomones released by three species of fish, Gambusia affinis (Cyprinodontiformes: Poeciliidae), Aphanius mento (Cyprinodontiformes: Cyprinodontidae) and Garra rufa (Cypriniformes: Cyprinidae) during oviposition. In addition, the study examined the effects of kairomones released by Gm. affinis on larval development and survival. Results show that ovipositing female avoided cues from the two larvivorous fish species but not the algivorous Gr. rufa. In addition, developing larvae metamorphosed slower and showed increased mortality when exposed to fish-released kairomones. Culiseta longiareolata larvae are known as dominant competitors, and the straightforward responses of both larvae and adult female to fish-released kairomones may be explained by the lack of additional sources of larval stress other than the presence of predators.

Keywords:  life history; oviposition habitat selection; predator-released kairomone

DOI:  https://doi.org/10.1093/jme/tjab145
Am J Trop Med Hyg. 2021 Aug 23. pii: tpmd200229. [Epub ahead of print]

Pyrethroid Resistance in Anopheles gambiae Not Associated with Insecticide-Treated Mosquito Net Effectiveness Across Sub-Saharan Africa.

David A Larsen, Rachael L Church.

Pyrethroid resistance is a major concern for malaria vector control programs that predominantly rely on insecticide-treated mosquito nets (ITNs). Contradictory results of the impact of resistance have been observed during field studies. We combined continent-wide estimates of pyrethroid resistance in Anopheles gambiae from 2006 to 2017, with continent-wide survey data to assess the effect of increasing pyrethroid resistance on the effectiveness of ITNs to prevent malaria infections in sub-Saharan Africa. We used a pooled-data approach and a meta-regression of survey regions to assess how pyrethroid resistance affects the association between ITN ownership and malaria outcomes for children 6 to 59 months of age. ITN ownership reduced the risk of malaria outcomes according to both the pooled and meta-regression approaches. According to the pooled analysis, there was no observed interaction between ITN ownership and estimated level of pyrethroid resistance (likelihood ratio [LR] test, 1.127 for malaria infection confirmed by the rapid diagnostic test, P = 0.2885; LR test = 0.161 for microscopy-confirmed malaria infection, P = 0.161; LR test = 0.646 for moderate or severe anemia, P = 0.4215). Using the meta-regression approach to determine the level of pyrethroid resistance did not explain any of the variance in subnational estimates of ITN effectiveness for any of the outcomes. ITNs decreased the risk of malaria independent of the levels of pyrethroid resistance in malaria vector populations.

DOI: https://doi.org/10.4269/ajtmh.20-0229
Insects. 2021 Jul 27. pii: 676. [Epub ahead of print]12(8):

Evolution of Adaptive Variation in the Mosquito Culex pipiens: Multiple Independent Origins of Insecticide Resistance Mutations.

Valentina Mastrantonio, Daniele Porretta, Valentina Lucchesi, Nurper Güz, Naciye Sena Çağatay, Romeo Bellini, John Vontas, Sandra Urbanelli.

  Insecticide resistance is an informative model for studying the appearance of adaptive traits. Simultaneously, understanding how many times resistance mutations originate is essential to design effective resistance management. In the mosquito Culex pipiens, target-site resistance to the insecticide diflubenzuron (DFB) has been recently found in Italian and Turkish populations. Three point mutations confer it at the codon 1043 of the chitin synthase 1 gene (chs-1): I1043L, I1043M, and I1043F. Whether the resistant mutations originated independently from different susceptible alleles or sequentially from resistant alleles and whether resistant alleles from Italy and Turkey have originated once or multiple times remain unresolved. Here, we sequenced a fragment of the chs-1 gene carrying the resistant mutations and inferred the phylogenetic relationships among susceptible and resistant alleles. Confirming previous findings, we found the three mutations in Italy and the I1043M in Turkey. Notably, the I1043F was also found for the first time in Turkish samples, highlighting the need for extensive monitoring activities. Phylogenetic analyses are consistent with an independent origin of the I1043F, I1043M, and I1043L mutations from different susceptible alleles and with multiple independent origins of the Italian and Turkish I1043M and I1043F alleles.

Keywords:  Chitin synthase; insect growth regulators; insecticide resistance; vector control

DOI:  https://doi.org/10.3390/insects12080676
Rev Med Virol. 2021 Aug 24. e2287

The global emergence of Chikungunya infection: An integrated view.

Khanzadi Nazneen Manzoor, Farakh Javed, Muhammad Ejaz, Mubashar Ali, Neelam Mujaddadi, Abid Ali Khan, Aamer Ali Khattak, Assad Zaib, Ibrar Ahmad, Waqar Khalid Saeed, Sobia Manzoor.

  Chikungunya virus (CHIKV) is one of the emerging viruses around the globe. It belongs to the family Togaviridae and genus Alphavirus and is an arthropod borne virus that transmits by the bite of an infected mosquito, mainly through Aedes aegypti and Aedes albopcitus. It is a spherical, enveloped virus with positive single stranded RNA genome. It was first discovered during 1952-53 in Tanganyika, after which outbreaks were documented in many regions of the world. CHIKV has two transmission cycles; an enzootic sylvatic cycle and an urban cycle. CHIKV genome contains 11,900 nucleotides and two open reading frames and shows great sequence variability. Molecular mechanisms of virus host-cell interactions and the pathogenesis of disease are not fully understood. The disease involves three phases; acute, post-acute and chronic with symptoms including high-grade fever, arthralgia, macupapular rashes and headache. There is no licensed vaccine or specific treatment for CHIKV infection. This lack of specific interventions combined with difficulties in making a precise diagnosis together make the disease difficult to manage. In this review we aim to present the current knowledge of global epidemiology, transmission, structure, various aspects of diagnosis as well as highlight potential antiviral drugs and vaccines against CHIKV.

Keywords:  Aedes aegypti; Aedes albopictus; Chikungunya virus; alpha virus

DOI:  https://doi.org/10.1002/rmv.2287
Insects. 2021 Aug 20. pii: 752. [Epub ahead of print]12(8):

Evaluation of Total Female and Male Aedes aegypti Proteomes Reveals Significant Predictive Protein-Protein Interactions, Functional Ontologies, and Differentially Abundant Proteins.

Abubakar Shettima, Shaleni Joseph, Intan H Ishak, Syahirah Hanisah Abdul Raiz, Hadura Abu Hasan, Nurulhasanah Othman.

  Aedes aegypti is a significant vector for many tropical and subtropical flavivirus diseases. Only the female mosquito transmits pathogens, while the male plays a vital role in mating and species continuity. This study explored the total proteomes of females and males based on the physiological and genetic differences of female and male mosquitoes. Protein extracts from mosquitoes were analysed using LC-ESI-MS/MS for protein identification, protein interaction network analysis, functional ontology enrichment, and differential protein abundance analyses. Protein identification revealed 422 and 682 proteins exclusive to males and females, respectively, with 608 common proteins found in both sexes. The most significant PPIs (<1.0 × 10-16) were for common proteins, followed by proteins exclusive to females (<1.0 × 10-16) and males (1.58 × 10-12). Significant functional enrichments were observed in the biological process, molecular function, and cellular component for the male and female proteins. The abundance of the proteins differed, with one protein showing an increase (elongation factor 1 α, EF1α) and two showing reductions (actin family) in females versus males. Overall, the study verified the total proteomes differences between male and female Ae. aegypti based on protein identification and interactions, functional ontologies, and differentially abundant proteins. Some of the identified proteins merit further investigation to elucidate their roles in blocking viral transmission.

Keywords:  Ae. aegypti; LFQ; female; functional ontologies; male; protein identification; protein–protein interactions

DOI:  https://doi.org/10.3390/insects12080752
Pathogens. 2021 Aug 10. pii: 1007. [Epub ahead of print]10(8):

Mosquito-Borne Viral Pathogens Detected in Zambia: A Systematic Review.

Rachel Milomba Velu, Geoffrey Kwenda, Liyali Libonda, Caroline Cleopatra Chisenga, Bumbangi Nsoni Flavien, Obvious Nchimunya Chilyabanyama, Michelo Simunyandi, Samuel Bosomprah, Nicholus Chintu Sande, Katendi Changula, Walter Muleya, Monicah Mirai Mburu, Benjamin Mubemba, Simbarashe Chitanga, John Tembo, Matthew Bates, Nathan Kapata, Yasuko Orba, Masahiro Kajihara, Ayato Takada, Hirofumi Sawa, Roma Chilengi, Edgar Simulundu.

  Emerging and re-emerging mosquito-borne viral diseases are a threat to global health. This systematic review aimed to investigate the available evidence of mosquito-borne viral pathogens reported in Zambia. A search of literature was conducted in PubMed and Google Scholar for articles published from 1 January 1930 to 30 June 2020 using a combination of keywords. Eight mosquito-borne viruses belonging to three families, Togaviridae, Flaviviridae and Phenuiviridae were reported. Three viruses (Chikungunya virus, Mayaro virus, Mwinilunga virus) were reported among the togaviruses whilst four (dengue virus, West Nile virus, yellow fever virus, Zika virus) were among the flavivirus and only one virus, Rift Valley fever virus, was reported in the Phenuiviridae family. The majority of these mosquito-borne viruses were reported in Western and North-Western provinces. Aedes and Culex species were the main mosquito-borne viral vectors reported. Farming, fishing, movement of people and rain patterns were among factors associated with mosquito-borne viral infection in Zambia. Better diagnostic methods, such as the use of molecular tools, to detect the viruses in potential vectors, humans, and animals, including the recognition of arboviral risk zones and how the viruses circulate, are important for improved surveillance and design of effective prevention and control measures.

Keywords:  Flaviviridae; Phenuiviridae; Togaviridae; Zambia; arboviruses; mosquito-borne

DOI:  https://doi.org/10.3390/pathogens10081007
Microorganisms. 2021 Aug 10. pii: 1699. [Epub ahead of print]9(8):

West Nile Virus in the State of Ceará, Northeast Brazil.

Flávia Löwen Levy Chalhoub, Eudson Maia de Queiroz-Júnior, Bruna Holanda Duarte, Marcos Eielson Pinheiro de Sá, Pedro Cerqueira Lima, Ailton Carneiro de Oliveira, Lívia Medeiros Neves Casseb, Liliane Leal das Chagas, Hamilton Antônio de Oliveira Monteiro, Maycon Sebastião Alberto Santos Neves, Cyro Facundo Chaves, Paulo Jean da Silva Moura, Aline Machado Rapello do Nascimento, Rodrigo Giesbrecht Pinheiro, Antonio Roberio Soares Vieira, Francisco Bergson Pinheiro Moura, Luiz Osvaldo Rodrigues da Silva, Kiliana Nogueira Farias da Escóssia, Lindenberg Caranha de Sousa, Izabel Leticia Cavalcante Ramalho, Antônio Williams Lopes da Silva, Leda Maria Simōes Mello, Fábio Felix de Souza, Francisco das Chagas Almeida, Raí Dos Santos Rodrigues, Diego do Vale Chagas, Anielly Ferreira-de-Brito, Karina Ribeiro Leite Jardim Cavalcante, Maria Angélica Monteiro de Mello Mares-Guia, Vinícius Martins Guerra Campos, Nieli Rodrigues da Costa Faria, Marcelo Adriano da Cunha E Silva Vieira, Marcos Cesar Lima de Mendonça, Nayara Camila Amorim de Alvarenga Pivisan, Jarier de Oliveira Moreno, Maria Aldessandra Diniz Vieira, Ricristhi Gonçalves de Aguiar Gomes, Fernanda Montenegro de Carvalho Araújo, Pedro Henrique de Oliveira Passos, Daniel Garkauskas Ramos, Alessandro Pecego Martins Romano, Lívia Carício Martins, Ricardo Lourenço-de-Oliveira, Ana Maria Bispo de Filippis, Alex Pauvolid-Corrêa.

  In June 2019, a horse with neurological disorder was diagnosed with West Nile virus (WNV) in Boa Viagem, a municipality in the state of Ceará, northeast Brazil. A multi-institutional task force coordinated by the Brazilian Ministry of Health was deployed to the area for case investigation. A total of 513 biological samples from 78 humans, 157 domestic animals and 278 free-ranging wild birds, as well as 853 adult mosquitoes of 22 species were tested for WNV by highly specific serological and/or molecular tests. No active circulation of WNV was detected in vertebrates or mosquitoes by molecular methods. Previous exposure to WNV was confirmed by seroconversion in domestic birds and by the detection of specific neutralizing antibodies in 44% (11/25) of equids, 20.9% (14/67) of domestic birds, 4.7% (13/278) of free-ranging wild birds, 2.6% (2/78) of humans, and 1.5% (1/65) of small ruminants. Results indicate that not only equines but also humans and different species of domestic animals and wild birds were locally exposed to WNV. The detection of neutralizing antibodies for WNV in free-ranging individuals of abundant passerine species suggests that birds commonly found in the region may have been involved as amplifying hosts in local transmission cycles of WNV.

Keywords:  Boa Viagem; Brazil; Ceará; PRNT; West Nile virus; equids

DOI:  https://doi.org/10.3390/microorganisms9081699
Viruses. 2021 Jul 28. pii: 1475. [Epub ahead of print]13(8):

Yellow Fever Outbreak in Eastern Senegal, 2020-2021.

Moussa Moïse Diagne, Marie Henriette Dior Ndione, Alioune Gaye, Mamadou Aliou Barry, Diawo Diallo, Amadou Diallo, Lusajo L Mwakibete, Mamadou Diop, El Hadji Ndiaye, Vida Ahyong, Babacar Diouf, Moufid Mhamadi, Cheikh Tidiane Diagne, Fodé Danfakha, Boly Diop, Oumar Faye, Cheikh Loucoubar, Gamou Fall, Cristina M Tato, Amadou Alpha Sall, Scott C Weaver, Mawlouth Diallo, Ousmane Faye.

  Yellow fever virus remains a major threat in low resource countries in South America and Africa despite the existence of an effective vaccine. In Senegal and particularly in the eastern part of the country, periodic sylvatic circulation has been demonstrated with varying degrees of impact on populations in perpetual renewal. We report an outbreak that occurred from October 2020 to February 2021 in eastern Senegal, notified and managed through the synergistic effort yellow fever national surveillance implemented by the Senegalese Ministry of Health in collaboration with the World Health Organization, the countrywide 4S network set up by the Ministry of Health, the Institut Pasteur de Dakar, and the surveillance of arboviruses and hemorrhagic fever viruses in human and vector populations implemented since mid 2020 in eastern Senegal. Virological analyses highlighted the implication of sylvatic mosquito species in virus transmission. Genomic analysis showed a close relationship between the circulating strain in eastern Senegal, 2020, and another one from the West African lineage previously detected and sequenced two years ago from an unvaccinated Dutch traveler who visited the Gambia and Senegal before developing signs after returning to Europe. Moreover, genome analysis identified a 6-nucleotide deletion in the variable domain of the 3'UTR with potential impact on the biology of the viral strain that merits further investigations. Integrated surveillance of yellow fever virus but also of other arboviruses of public health interest is crucial in an ecosystem such as eastern Senegal.

Keywords:  3′UTR; Kedougou; arbovirus; eastern Senegal; genotype; lineage; next generation sequencing; sylvatic lifecycle; virus isolation; yellow fever virus

DOI:  https://doi.org/10.3390/v13081475
Viruses. 2021 Jul 23. pii: 1441. [Epub ahead of print]13(8):

Serological Evidence of Widespread Zika Transmission across the Philippines.

Joseph R Biggs, Ava Kristy Sy, Oliver J Brady, Adam J Kucharski, Sebastian Funk, Yun-Hung Tu, Mary Anne Joy Reyes, Mary Ann Quinones, William Jones-Warner, James Ashall, Ferchito L Avelino, Nemia L Sucaldito, Amado O Tandoc, Eva Cutiongco-de la Paz, Maria Rosario Z Capeding, Carmencita D Padilla, Martin L Hibberd, Julius Clemence R Hafalla.

  Zika virus (ZIKV) exposure across flavivirus-endemic countries, including the Philippines, remains largely unknown despite sporadic case reporting and environmental suitability for transmission. Using laboratory surveillance data from 2016, 997 serum samples were randomly selected from suspected dengue (DENV) case reports across the Philippines and assayed for serological markers of short-term (IgM) and long-term (IgG) ZIKV exposure. Using mixture models, we re-evaluated ZIKV IgM/G seroprevalence thresholds and used catalytic models to quantify the force of infection (attack rate, AR) from age-accumulated ZIKV exposure. While we observed extensive ZIKV/DENV IgG cross-reactivity, not all individuals with active DENV presented with elevated ZIKV IgG, and a proportion of dengue-negative cases (DENV IgG-) were ZIKV IgG-positive (14.3%, 9/63). We identified evidence of long-term, yet not short-term, ZIKV exposure across Philippine regions (ZIKV IgG+: 31.5%, 314/997) which was geographically uncorrelated with DENV exposure. In contrast to the DENV AR (12.7% (95%CI: 9.1-17.4%)), the ZIKV AR was lower (5.7% (95%CI: 3-11%)) across the country. Our results provide evidence of widespread ZIKV exposure across the Philippines and suggest the need for studies to identify ZIKV infection risk factors over time to better prepare for potential future outbreaks.

Keywords:  Philippines; Zika; dengue; diagnostics; force of infection; serology

DOI:  https://doi.org/10.3390/v13081441
Trop Med Infect Dis. 2021 Aug 14. pii: 152. [Epub ahead of print]6(3):

A Cluster of Dengue Cases in Travelers: A Clinical Series from Thailand.

Hisham A Imad, Juthamas Phadungsombat, Emi E Nakayama, Lapakorn Chatapat, Phimphan Pisutsan, Wasin Matsee, Watcharapong Piyaphanee, Wang Nguitragool, Tatsuo Shioda.

  Dengue is an overlooked tropical disease for which billions of people are at risk. The disease, caused by a Flavivirus with four distinct serotypes, is transmitted primarily by urban Aedes mosquito species. The infection leads to a spectrum of clinical manifestations, with the majority being asymptomatic. Primary dengue fever and, to a greater extent, a subsequent infection with a different serotype is associated with increased severity. Increased global travel and recreational tourism expose individuals naïve to the dengue viruses, the most common arboviral infections among travelers. We describe a cluster of possible primary acute dengue infections in a group of 12 individuals who presented to Bangkok Hospital for Tropical Diseases in 2017. Infection was confirmed by dengue NS1 antigen and multiplex real-time RT-PCR. Nine individuals required hospitalization, and four developed dengue warning signs. Leukocytes, neutrophils, and platelets declined towards defervescence and were negatively correlated with day of illness. Six clinical isolates were identified as dengue serotype-1, with 100% nucleotide identity suggesting that these patients were infected with the same virus.

Keywords:  Flavivirus; dengue; dengue warning signs; primary infection; serotype-1

DOI:  https://doi.org/10.3390/tropicalmed6030152