bims-mosdis 2023-04-09 papers

bims-mosdis

Biomed News

on Mosquito distribution and disease

Issue of 2023–04–09
ten papers selected by
Richard Halfpenny, Staffordshire University

The first confirmed outbreak of Barmah Forest virus in Tasmania - 2019.
The first molecular confirmation of Culex pipiens complex as potential natural vectors of Dirofilaria immitis in Myanmar.
Current status of insecticide resistance and its underlying mechanisms in Aedes aegypti (L.) in Punjab, Pakistan.
Circulation of West Nile virus in mosquitoes approximate to the migratory bird stopover in West Coast Malaysia.
Malaria transmission pattern across the Sahelian, humid savanna, highland and forest eco-epidemiological settings in Cameroon.
Effect of passive and active ventilation on malaria mosquito house entry and human comfort: an experimental study in rural Gambia.
Chikungunya fever.
Epidemic versus endemic West Nile virus dead bird surveillance in California: Changes in sensitivity and focus.
Fine-scale mapping of urban malaria exposure under data scarcity: an approach centred on vector ecology.
Evolutionary dynamics of dengue virus in India.

Aust N Z J Public Health. 2023 Mar 31. pii: S1326-0200(23)01562-5. [Epub ahead of print]47(2): 100039

The first confirmed outbreak of Barmah Forest virus in Tasmania - 2019.

Hayley Dyke, Kerryn Lodo, Nicola Stephens, Scott Carver.

   OBJECTIVE: To describe the first outbreak of Barmah Forest virus (BFv) in Tasmania and identify potential vectors for BFv in Tasmania.
METHODS: A retrospective descriptive study of BFv notifications in the Tasmanian Notifiable Diseases Database (TNDD) was conducted. Adult mosquitoes were sampled from areas near outbreak cases and pooled samples were tested for BFv.
RESULTS: 27 cases of confirmed BFv were recorded in the TNDD between 12 March 1999 and 30 June 2019. Nine cases were recorded between 21 January and 10 May 2019 that were acquired in Tasmania, with eight included in this confirmed outbreak. All outbreak cases resided in or travelled to locations in the Break O'Day Local Government Area and reported no recent interstate travel. No virus was detected in pooled mosquito samples.
CONCLUSIONS: This is Tasmania's first confirmed outbreak of BFv. Known BFv vector species were identified in both saltmarsh and urban-fringe brackish saltmarsh larval habitats. BFv was not detected from pooled mosquito samples.
IMPLICATIONS FOR PUBLIC HEALTH: Clinicians should consider BFv as a possible diagnosis for presentations with fever and arthritis, and potential mosquito exposure in Tasmania. These findings will guide broadening of prevention-focussed public health messaging.

Keywords:  Barmah Forest virus; arbovirus; outbreak; tasmania

DOI:  https://doi.org/10.1016/j.anzjph.2023.100039
Med Vet Entomol. 2023 Apr 05.

The first molecular confirmation of Culex pipiens complex as potential natural vectors of Dirofilaria immitis in Myanmar.

Si Thu Aung, Saw Bawm, Hla Myet Chel, Lat Lat Htun, Soe Soe Wai, Yuki Eshita, Ken Katakura, Ryo Nakao.

  Dirofilariosis, known as one of the most widespread vector-borne zoonotic diseases, is caused by several different species of the nematodes of the genus Dirofilaria, which can be transmitted by Culex, Anopheles and Aedes mosquito vectors. In order to identify key vector mosquitoes of filarial parasites in Myanmar, mosquitoes were collected during three different seasons (summer, rainy and winter) in three townships in Nay Pyi Taw area, Myanmar. DNA extraction and polymerase chain reaction (PCR) analyses were conducted for 185 mosquito pools, with each pool containing 1-10 mosquitoes. Dirofilaria immitis was detected in 20 pools of Culex pipiens complex mosquitoes. The minimum infection rate of mosquitoes was found to be 16.33. The small subunit ribosomal RNA (12S rDNA) gene targeted PCR revealed that the sequences obtained were completely identical to the sequences of D. immitis derived from dogs in China, Brazil and France. The sequences obtained from mitochondrial cytochrome oxidase subunit I (COI) gene PCR exhibited 100% identity with the sequences of D. immitis derived from dogs in Bangladesh, Iran, Japan and Thailand, as well as humans in Iran and Thailand, and mosquitoes in Germany and Hungary. The findings of this study demonstrated that the mosquito species of Cx. pipiens complex are potential mosquito vectors for dirofilariosis in Myanmar.

Keywords:  Culex pipiens complex; Dirofilaria immitis; Myanmar; molecular detection

DOI:  https://doi.org/10.1111/mve.12652
J Vector Borne Dis. 2023 Jan-Mar;60(1):60(1): 57-64

Current status of insecticide resistance and its underlying mechanisms in Aedes aegypti (L.) in Punjab, Pakistan.

Hania Ramzan, Farkhanda Manzoor, Muhammad Oneeb.

  Aedes aegypti (Linnaeus) plays an important role as a vector of different deadly diseases particularly dengue fever. Insecticides are used as a primary tool to control Ae. aegypti. However, due to the excessive use of insecticides on agricultural, public health, and industrial levels, mosquitoes have developed resistance. In this study, the current susceptibility status of Ae. aegypti mosquitoes against different insecticides (Temephos, DDT, dieldrin, Malathion, Bendiocarb, Permethrin, Cypermethrin, and Lambda-cyhalothrin) was evaluated in district Lahore and district Muzaffargarh of Punjab, Pakistan. For this purpose, WHO bioassays and biochemical assays were performed on Ae. aegypti population from Lahore (APLa) and Aedes population from Muzaffargarh (APMg). Results of APLa and APMg showed high levels of resistance against the larvicide Temephos. Resistance against all adulticides was also observed in APLa and APMg (% mortality < 98%). The biochemical assays indicated statistically significant elevated levels of detoxification enzymes in APLa and APMg. APLa showed slightly higher levels as compared to APMg. Mosquitoes were also screened for the presence of kdr mutations. The results revealed no mutation in domain II while the presence of mutation F1534C in domain III was found in both field populations. The results showed the presence of moderate to high grade resistance against all insecticides in Ae. aegypti in district Lahore and district Muzaffargarh of Punjab, Pakistan.

Keywords:  Aedes aegypti; Agro-ecological zones; Metabolic resistance; kdr mutations

DOI:  https://doi.org/10.4103/0972-9062.353250
PLoS Negl Trop Dis. 2023 Apr 06. 17(4): e0011255

Circulation of West Nile virus in mosquitoes approximate to the migratory bird stopover in West Coast Malaysia.

Jafar Ali Natasha, Abd Rahaman Yasmin, Reuben Sunil Kumar Sharma, Saulol Hamid Nur-Fazila, Md Isa Nur-Mahiza, Siti Suri Arshad, Hussni Omar Mohammed, Kiven Kumar, Shih Keng Loong, Mohd Kharip Shah Ahmad Khusaini.

Being a tropical country with a conducive environment for mosquitoes, mosquito-borne illnesses such as dengue, chikungunya, lymphatic filariasis, malaria, and Japanese encephalitis are prevalent in Malaysia. Recent studies reported asymptomatic infection of West Nile virus (WNV) in animals and humans, but none of the studies included mosquitoes, except for one report made half a century ago. Considering the scarcity of information, our study sampled mosquitoes near migratory bird stopover wetland areas of West Coast Malaysia located in the Kuala Gula Bird Sanctuary and Kapar Energy Venture, during the southward migration period in October 2017 and September 2018. Our previous publication reported that migratory birds were positive for WNV antibody and RNA. Using a nested RT-PCR analysis, WNV RNA was detected in 35 (12.8%) out of 285 mosquito pools consisting of 2,635 mosquitoes, most of which were Culex spp. (species). Sanger sequencing and phylogenetic analysis revealed that the sequences grouped within lineage 2 and shared 90.12%-97.01% similarity with sequences found locally as well as those from Africa, Germany, Romania, Italy, and Israel. Evidence of WNV in the mosquitoes substantiates the need for continued surveillance of WNV in Malaysia.

DOI: https://doi.org/10.1371/journal.pntd.0011255
Malar J. 2023 Apr 07. 22(1): 116

Malaria transmission pattern across the Sahelian, humid savanna, highland and forest eco-epidemiological settings in Cameroon.

Nelly Armanda Kala Chouakeu, Timoléon Tchuinkam, Roland Bamou, Mabu Maxim Bindamu, Abdou Talipouo, Edmond Kopya, Parfait Awono-Ambene, Christophe Antonio-Nkondjio.

   BACKGROUND: Malaria remains a major public health concern in Cameroon. Understanding vector distribution and malaria transmission dynamics is of paramount importance for evaluating the performance of control strategies. This study assesses patterns of malaria transmission in four eco-epidemiological settings in Cameroon.
METHODS: Adult mosquitoes were collected using Human Landing Catches (HLC) once every 4 months from August 2019 to November 2021 in Kaélé, Tibati, Santchou and Bertoua. Mosquitoes were sorted by genus and Anopheles gambiae sensu lato (s.l.) species complex were identified using PCR. The presence of Plasmodium falciparum circumsporozoite protein (CSP) was measured by ELISA; the entomological inoculation rates (EIR) was estimated in each locality.
RESULTS: A total of 23,536 mosquitoes were collected. Anopheles gambiae and/or Anopheles coluzzii were the main malaria vectors in all sites. Anopheles arabiensis was recorded in low frequency in Kaélé and Tibati. Other species collected included Anopheles funestus, Anopheles pharoensis and Anopheles ziemmani. High anopheline biting rates were recorded outdoor in all sites except in Kaélé. Important differences in species biting dynamics were observed between sites. The sporozoite infection rate varied from 0.36 to 4%. The daily EIR was found to vary from 0.07 in Santchou to 0.26 infected bites/man/night (ib/m/n) in Kaélé).
CONCLUSION: The study suggests heterogeneous patterns of malaria transmission in different ecoepidemiological settings across the country. The findings stress the need to improve malaria vector control strategies.

Keywords:  Anopheles; Cameroon; Eco-epidemiological settings; Malaria; Transmission

DOI:  https://doi.org/10.1186/s12936-023-04544-z
J R Soc Interface. 2023 Apr;20(201): 20220794

Effect of passive and active ventilation on malaria mosquito house entry and human comfort: an experimental study in rural Gambia.

Majo Carrasco-Tenezaca, Musa Jawara, Daniel Sang-Hoon Lee, Matthew S Holmes, Sainey Ceesay, Phillip McCall, Margaret Pinder, Umberto D'Alessandro, Jakob B Knudsen, Steve W Lindsay, Anne L Wilson.

  Rural houses in sub-Saharan Africa are typically hot and allow malaria mosquitoes inside. We assessed whether passive or active ventilation can reduce house entry of malaria mosquitoes and cool a bedroom at night in rural Gambia. Two identical experimental houses were used: one ventilated and one unventilated (control). We evaluated the impact of (i) passive ventilation (solar chimney) and (ii) active ventilation (ceiling fan) on the number of mosquitoes collected indoors and environmental parameters (temperature, humidity, CO2, evaporation). Although the solar chimney did not reduce entry of Anopheles gambiae sensu lato, the ceiling fan reduced house entry by 91% compared with the control house. There were no differences in indoor nightly temperature, humidity or CO2 between intervention and control houses in either experiment. The solar chimney did not improve human comfort assessed using psychrometric analysis. While the ceiling fan improved human comfort pre-midnight, in the morning it was too cool compared with the control house, although this could be remedied through provision of blankets. Further improvements to the design of the solar chimney are needed. High air velocity in the ceiling fan house probably reduced mosquito house entry by preventing mosquito flight. Improved ventilation in houses may reduce malaria transmission.

Keywords:  Africa; house design; human comfort; malaria; mosquito; ventilation

DOI:  https://doi.org/10.1098/rsif.2022.0794
Nat Rev Dis Primers. 2023 Apr 06. 9(1): 17

Chikungunya fever.

Koen Bartholomeeusen, Matthieu Daniel, Desiree A LaBeaud, Philippe Gasque, Rosanna W Peeling, Kathryn E Stephenson, Lisa F P Ng, Kevin K Ariën.

Chikungunya virus is widespread throughout the tropics, where it causes recurrent outbreaks of chikungunya fever. In recent years, outbreaks have afflicted populations in East and Central Africa, South America and Southeast Asia. The virus is transmitted by Aedes aegypti and Aedes albopictus mosquitoes. Chikungunya fever is characterized by severe arthralgia and myalgia that can persist for years and have considerable detrimental effects on health, quality of life and economic productivity. The effects of climate change as well as increased globalization of commerce and travel have led to growth of the habitat of Aedes mosquitoes. As a result, increasing numbers of people will be at risk of chikungunya fever in the coming years. In the absence of specific antiviral treatments and with vaccines still in development, surveillance and vector control are essential to suppress re-emergence and epidemics.

DOI: https://doi.org/10.1038/s41572-023-00429-2
PLoS One. 2023 ;18(4): e0284039

Epidemic versus endemic West Nile virus dead bird surveillance in California: Changes in sensitivity and focus.

Leslie Foss, Tina Feiszli, Vicki L Kramer, William K Reisen, Kerry Padgett.

Since 2003, the California West Nile virus (WNV) dead bird surveillance program (DBSP) has monitored publicly reported dead birds for WNV surveillance and response. In the current paper, we compared DBSP data from early epidemic years (2004-2006) with recent endemic years (2018-2020), with a focus on specimen collection criteria, county report incidence, bird species selection, WNV prevalence in dead birds, and utility of the DBSP as an early environmental indicator of WNV. Although fewer agencies collected dead birds in recent years, most vector control agencies with consistent WNV activity continued to use dead birds as a surveillance tool, with streamlined operations enhancing efficiency. The number of dead bird reports was approximately ten times greater during 2004-2006 compared to 2018-2020, with reports from the Central Valley and portions of Southern California decreasing substantially in recent years; reports from the San Francisco Bay Area decreased less dramatically. Seven of ten counties with high numbers of dead bird reports were also high human WNV case burden areas. Dead corvid, sparrow, and quail reports decreased the most compared to other bird species reports. West Nile virus positive dead birds were the most frequent first indicators of WNV activity by county in 2004-2006, followed by positive mosquitoes; in contrast, during 2018-2020 mosquitoes were the most frequent first indicators followed by dead birds, and initial environmental WNV detections occurred later in the season during 2018-2020. Evidence for WNV impacts on avian populations and susceptibility are discussed. Although patterns of dead bird reports and WNV prevalence in tested dead birds have changed, dead birds have endured as a useful element within our multi-faceted WNV surveillance program.

DOI: https://doi.org/10.1371/journal.pone.0284039
Malar J. 2023 Apr 03. 22(1): 113

Fine-scale mapping of urban malaria exposure under data scarcity: an approach centred on vector ecology.

Sabine Vanhuysse, Seynabou Mocote Diédhiou, Taïs Grippa, Stefanos Georganos, Lassana Konaté, El Hadji Amadou Niang, Eléonore Wolff.

   BACKGROUND: Although malaria transmission has experienced an overall decline in sub-Saharan Africa, urban malaria is now considered an emerging health issue due to rapid and uncontrolled urbanization and the adaptation of vectors to urban environments. Fine-scale hazard and exposure maps are required to support evidence-based policies and targeted interventions, but data-driven predictive spatial modelling is hindered by gaps in epidemiological and entomological data. A knowledge-based geospatial framework is proposed for mapping the heterogeneity of urban malaria hazard and exposure under data scarcity. It builds on proven geospatial methods, implements open-source algorithms, and relies heavily on vector ecology knowledge and the involvement of local experts.
METHODS: A workflow for producing fine-scale maps was systematized, and most processing steps were automated. The method was evaluated through its application to the metropolitan area of Dakar, Senegal, where urban transmission has long been confirmed. Urban malaria exposure was defined as the contact risk between adult Anopheles vectors (the hazard) and urban population and accounted for socioeconomic vulnerability by including the dimension of urban deprivation that is reflected in the morphology of the built-up fabric. Larval habitat suitability was mapped through a deductive geospatial approach involving the participation of experts with a strong background in vector ecology and validated with existing geolocated entomological data. Adult vector habitat suitability was derived through a similar process, based on dispersal from suitable breeding site locations. The resulting hazard map was combined with a population density map to generate a gridded urban malaria exposure map at a spatial resolution of 100 m.
RESULTS: The identification of key criteria influencing vector habitat suitability, their translation into geospatial layers, and the assessment of their relative importance are major outcomes of the study that can serve as a basis for replication in other sub-Saharan African cities. Quantitative validation of the larval habitat suitability map demonstrates the reliable performance of the deductive approach, and the added value of including local vector ecology experts in the process. The patterns displayed in the hazard and exposure maps reflect the high degree of heterogeneity that exists throughout the city of Dakar and its suburbs, due not only to the influence of environmental factors, but also to urban deprivation.
CONCLUSIONS: This study is an effort to bring geospatial research output closer to effective support tools for local stakeholders and decision makers. Its major contributions are the identification of a broad set of criteria related to vector ecology and the systematization of the workflow for producing fine-scale maps. In a context of epidemiological and entomological data scarcity, vector ecology knowledge is key for mapping urban malaria exposure. An application of the framework to Dakar showed its potential in this regard. Fine-grained heterogeneity was revealed by the output maps, and besides the influence of environmental factors, the strong links between urban malaria and deprivation were also highlighted.

Keywords:  Earth observation; Framework; Malaria exposure; Spatial analysis; Sub-Saharan Africa; Urban malaria; Vector ecology; Vector habitat suitability

DOI:  https://doi.org/10.1186/s12936-023-04527-0
PLoS Pathog. 2023 Apr 03. 19(4): e1010862

Evolutionary dynamics of dengue virus in India.

Suraj Jagtap, Chitra Pattabiraman, Arun Sankaradoss, Sudhir Krishna, Rahul Roy.

More than a hundred thousand dengue cases are diagnosed in India annually, and about half of the country's population carries dengue virus-specific antibodies. Dengue propagates and adapts to the selection pressures imposed by a multitude of factors that can lead to the emergence of new variants. Yet, there has been no systematic analysis of the evolution of the dengue virus in the country. Here, we present a comprehensive analysis of all DENV gene sequences collected between 1956 and 2018 from India. We examine the spatio-temporal dynamics of India-specific genotypes, their evolutionary relationship with global and local dengue virus strains, interserotype dynamics and their divergence from the vaccine strains. Our analysis highlights the co-circulation of all DENV serotypes in India with cyclical outbreaks every 3-4 years. Since 2000, genotype III of DENV-1, cosmopolitan genotype of DENV-2, genotype III of DENV-3 and genotype I of DENV-4 have been dominating across the country. Substitution rates are comparable across the serotypes, suggesting a lack of serotype-specific evolutionary divergence. Yet, the envelope (E) protein displays strong signatures of evolution under immune selection. Apart from drifting away from its ancestors and other contemporary serotypes in general, we find evidence for recurring interserotype drift towards each other, suggesting selection via cross-reactive antibody-dependent enhancement. We identify the emergence of the highly divergent DENV-4-Id lineage in South India, which has acquired half of all E gene mutations in the antigenic sites. Moreover, the DENV-4-Id is drifting towards DENV-1 and DENV-3 clades, suggesting the role of cross-reactive antibodies in its evolution. Due to the regional restriction of the Indian genotypes and immunity-driven virus evolution in the country, ~50% of all E gene differences with the current vaccines are focused on the antigenic sites. Our study shows how the dengue virus evolution in India is being shaped in complex ways.

DOI: https://doi.org/10.1371/journal.ppat.1010862