bims-mosdis 2022-10-23 papers

bims-mosdis

Biomed News

on Mosquito distribution and disease

Issue of 2022–10–23
twelve papers selected by
Richard Halfpenny, Staffordshire University

Methodological procedures explain observed differences in the competence of European populations of Aedes albopictus for the transmission of Zika virus.
Susceptibility of primary, secondary and suspected vectors to Plasmodium vivax and Plasmodium falciparum infection in Ethiopia.
Demographic and environmental factors associated with the distribution of Aedes albopictus in Cameroon.
The distinctive bionomics of Aedes aegypti populations in Africa.
Building the capacity of West African countries in Aedes surveillance: inaugural meeting of the West African Aedes Surveillance Network (WAASuN).
Use of mobile data collection systems within large-scale epidemiological field trials: findings and lessons-learned from a vector control trial in Iquitos, Peru.
Malaria metrics distribution under global warming: assessment of the VECTRI malaria model over Cameroon.
Malaria Knowledge-Base and Prevalence of Parasitaemia in Asymptomatic Adults in the Forest Zone of Ghana.
The global trends and regional differences in incidence of Zika virus infection and implications for Zika virus infection prevention.
LLIN Evaluation in Uganda Project (LLINEUP2)-Factors associated with coverage and use of long‑lasting insecticidal nets following the 2020-21 national mass distribution campaign: a cross-sectional survey of 12 districts.
House screening for malaria control: views and experiences of participants in the RooPfs trial.
Yellow fever outbreak in Kenya: A review.

Acta Trop. 2022 Oct 18. pii: S0001-706X(22)00416-8. [Epub ahead of print] 106724

Methodological procedures explain observed differences in the competence of European populations of Aedes albopictus for the transmission of Zika virus.

Rafael Gutiérrez-López, Jordi Figuerola, Josué Martínez-de la Puente.

  The risk of autochthonous transmission of Zika virus (ZIKV) in Europe greatly depends on the capacity of Aedes albopictus to transmit ZIKV. Experimental studies of the vector competence of European populations of this invasive mosquito species provided contrasting results, that may suggest differences between mosquito populations in ZIKV competence and/or differences in the methodological procedures used on the experimental studies. We systematically reviewed published studies of experimental mosquito infections and show that differences detected in the infection and transmission rates of Ae. albopictus are mostly due to differences between studies in the temperature, the viral load used to inoculate mosquitoes, and the number of days post-exposure (dpe) to the virus at which mosquitoes were analysed. In particular, the proportion of infected mosquitoes was affected by the viral load inoculated and the dpe, whereas the transmission rate was influenced by the viral load and temperature. Thus, the methodological differences used in these studies greatly affect the conclusions obtained regarding the role of Ae. albopictus in Europe as a competent vector for ZIKV and its epidemiological relevance.

Keywords:  arbovirus; experimental infection; mosquito; vector competence; vector-borne diseases

DOI:  https://doi.org/10.1016/j.actatropica.2022.106724
Parasit Vectors. 2022 Oct 21. 15(1): 384

Susceptibility of primary, secondary and suspected vectors to Plasmodium vivax and Plasmodium falciparum infection in Ethiopia.

Arega Tsegaye, Assalif Demissew, Dawit Hawaria, Hallelujah Getachew, Kassahun Habtamu, Abebe Asale, Guiyun Yan, Delenasaw Yewhalaw.

   BACKGROUND: Insecticide-based vector control interventions in combination with case management with artemisinin-based combination therapy has reduced malaria incidence and prevalence worldwide. Current control methods focus on the primary malaria vectors, Anopheles gambiae sensu lato (s.l.) and the An. funestus group; however, the impact of secondary and suspected vectors has been either sidelined or received limited attention. Defining the susceptibility of secondary, suspected vector species to different parasites in time and space is essential for efficient malaria control and elimination programs. The aim of this study was to assess the susceptibility of An. gambiae s.l., An. coustani complex and An. pharoensis to Plasmodium vivax and P. falciparum infection in Ethiopia.
METHODS: Larvae of Anopheles spp. were collected from different aquatic habitats and reared to adults under laboratory conditions, with the temperature and humidity maintained at 27 ± 1 °C and 75 ± 5%, respectively. Adult female mosquitoes were identified to species as An. gambiae s.l., An. coustani complex and An. pharoensis. Females of these three Anopheles spp. were allowed to feed in parallel feeding assays on infected blood containing the same gametocytes isolated from P. falciparum and P. vivax gametocyte-positive patients by indirect membrane feeding assays. All blood-fed mosquitoes were held under laboratory conditions. After 7 days, all surviving mosquitoes were dissected to detect mid-gut oocyst and enumerated under a microscope.
RESULTS: Of 5915 female Anopheles mosquitoes exposed to gametocyte-infected blood, 2106 (35.6%)s fed successfully in the 32 independent infection experiments. There was a significant variation in feeding rates among An. gambiae s.l., An. pharoensis and An. coustani complex (G-test = 48.43, P = 3.049e-11). All three exposed mosquito species were receptive to P. vivax and P. falciparum infection development. The percentage of infected mosquitoes following feeding on an infected blood meal was significantly different among species (G-test = 6.49, P = 0.03886). The median infection intensity (II) for An. coustani complex, An. gambiae s.l. and An. pharoensis was 1.16, 2.00 and 1.25, respectively. Although the proportion of infected mosquitoes significantly differed in terms of II, infection rate (IR) and mean oocyst density among the species, mean oocyst density and IR were highly correlated with gametocyte density in all tests (P < 0.001).
CONCLUSION: Primary, secondary and suspected vectors were experimentally susceptible to both P. vivax and P. falciparum infection. An effective malaria elimination program might include surveillance and control tools which target secondary and suspected vectors that might play an outdoor transmission role, possibly resulting in reduced focal malaria transmission. Comparison of the three species' mean infection rates with standard deviation.

Keywords:  Anopheles; Ethiopia; Infection rate; Malaria; Membrane feeding assay; Oocysts; Plasmodium species

DOI:  https://doi.org/10.1186/s13071-022-05467-5
Med Vet Entomol. 2022 Oct 20.

Demographic and environmental factors associated with the distribution of Aedes albopictus in Cameroon.

Tiago Canelas, Edward Thomsen, Basile Kamgang, Louise A Kelly-Hope.

  Aedes-transmitted arboviruses have spread globally due to the spread of Aedes aegypti and Aedes albopictus. Its distribution is associated with human and physical geography. However, these factors have not been quantified in Cameroon. Therefore, the aim was to develop an Ae. albopictus geo-referenced database to examine the risk factors associated with the vector distribution in Cameroon. Data on the Ae. albopictus presence and absence were collated and mapped from studies in published scientific literature between 2000 and 2020. Publicly available earth observation data were used to assess human geography, land use and climate risk factors related to the vector distribution. A logistic binomial regression was conducted to identify the significant risk factors associated with Ae. albopictus distribution. In total, 111 data points were collated (presence = 87; absence = 24). Different data collection methods and sites hindered the spatiotemporal analysis. An increase of one wet month in a year increased the odds of Ae. albopictus presence by 5.6 times. One unit of peri-urban area increased the odds by 1.3 times. Using publicly available demographic and environmental data to better understand the key determinants of mosquito distributions may facilitate appropriately targeted public health messages and vector control strategies.

Keywords:  Aedes; Aedes albopictus; Arbovirus; Cameroon

DOI:  https://doi.org/10.1111/mve.12619
Curr Opin Insect Sci. 2022 Oct 12. pii: S2214-5745(22)00121-3. [Epub ahead of print] 100986

The distinctive bionomics of Aedes aegypti populations in Africa.

David P Tchouassi, Sheila B Agha, Jandouwe Villinger, Rosemary Sang, Baldwyn Torto.

Aedes aegypti is the primary vector of dengue, chikungunya and Zika viruses of medical importance. Behavioral and biological attributes contribute to its vectorial capacity. The mosquito domestic form which resides outside Africa (Aaa) is considered to breed in artificial containers in and around homes and preferentially feeds on human blood but commonly indulges in a plant diet. Potential divergence in these attributes, in sub-Saharan Africa (SSA) where Aaa co-exists with the forest ecotype (Aaf), should impact the vectoring ability and hence disease epidemiology. A summary of current knowledge on Ae. aegypti blood-feeding, oviposition, and plant-feeding habits among SSA populations is provided in comparison with those in different geographies, globally. Emphasis is placed on improved understanding of the connection between changing subspecies adaptation in these traits and arbovirus disease risk in SSA in response to climate change and increasing urbanization, with the ultimate use of this information for effective disease control.

DOI: https://doi.org/10.1016/j.cois.2022.100986
Parasit Vectors. 2022 Oct 21. 15(1): 381

Building the capacity of West African countries in Aedes surveillance: inaugural meeting of the West African Aedes Surveillance Network (WAASuN).

WAASuN contributors

Arboviral diseases such as dengue, Zika and chikungunya transmitted by Aedes mosquitoes have been reported in 34 African countries. Available data indicate that in recent years there have been dengue and chikungunya outbreaks in the West Africa subregion, in countries including Côte d'Ivoire, Burkina Faso, Gabon, Senegal, and Benin. These viral diseases are causing an increased public health burden, which impedes poverty reduction and sustainable development. Aedes surveillance and control capacity, which are key to reducing the prevalence of arboviral infections, need to be strengthened in West Africa, to provide information essential for the formulation of effective vector control strategies and the prediction of arboviral disease outbreaks. In line with these objectives, the West African Aedes Surveillance Network (WAASuN) was created in 2017 at a meeting held in Sierra Leone comprising African scientists working on Aedes mosquitoes. This manuscript describes the proceedings and discusses key highlights of the meeting.

DOI: https://doi.org/10.1186/s13071-022-05507-0
BMC Public Health. 2022 Oct 15. 22(1): 1924

Use of mobile data collection systems within large-scale epidemiological field trials: findings and lessons-learned from a vector control trial in Iquitos, Peru.

William H Elson, Anna B Kawiecki, Marisa A P Donnelly, Arnold O Noriega, Jody K Simpson, Din Syafruddin, Ismail Ekoprayitno Rozi, Neil F Lobo, Christopher M Barker, Thomas W Scott, Nicole L Achee, Amy C Morrison.

  Vector-borne diseases are among the most burdensome infectious diseases worldwide with high burden to health systems in developing regions in the tropics. For many of these diseases, vector control to reduce human biting rates or arthropod populations remains the primary strategy for prevention. New vector control interventions intended to be marketed through public health channels must be assessed by the World Health Organization for public health value using data generated from large-scale trials integrating epidemiological endpoints of human health impact. Such phase III trials typically follow large numbers of study subjects to meet necessary power requirements for detecting significant differences between treatment arms, thereby generating substantive and complex datasets. Data is often gathered directly in the field, in resource-poor settings, leading to challenges in efficient data reporting and/or quality assurance. With advancing technology, mobile data collection (MDC) systems have been implemented in many studies to overcome these challenges. Here we describe the development and implementation of a MDC system during a randomized-cluster, placebo-controlled clinical trial evaluating the protective efficacy of a spatial repellent intervention in reducing human infection with Aedes-borne viruses (ABV) in the urban setting of Iquitos, Peru, as well as the data management system that supported it. We discuss the benefits, remaining capacity gaps and the key lessons learned from using a MDC system in this context in detail.

Keywords:  Aedes aegypti; Clinical trial; CommCare; Data monitoring; Data quality; Dengue; Mobile data collection; Spatial repellent; Vector control

DOI:  https://doi.org/10.1186/s12889-022-14301-7
Int J Biometeorol. 2022 Oct 18.

Malaria metrics distribution under global warming: assessment of the VECTRI malaria model over Cameroon.

Amelie D Mbouna, Alain T Tamoffo, Ernest O Asare, Andre Lenouo, Clement Tchawoua.

  Malaria is a critical health issue across the world and especially in Africa. Studies based on dynamical models helped to understand inter-linkages between this illness and climate. In this study, we evaluated the ability of the VECTRI community vector malaria model to simulate the spread of malaria in Cameroon using rainfall and temperature data from FEWS-ARC2 and ERA-interim, respectively. In addition, we simulated the model using five results of the dynamical downscaling of the regional climate model RCA4 within two time frames named near future (2035-2065) and far future (2071-2100), aiming to explore the potential effects of global warming on the malaria propagation over Cameroon. The evaluated metrics include the risk maps of the entomological inoculation rate (EIR) and the parasite ratio (PR). During the historical period (1985-2005), the model satisfactorily reproduces the observed PR and EIR. Results of projections reveal that under global warming, heterogeneous changes feature the study area, with localized increases or decreases in PR and EIR. As the level of radiative forcing increases (from 2.6 to 8.5 W.m-2), the magnitude of change in PR and EIR also gradually intensifies. The occurrence of transmission peaks is projected in the temperature range of 26-28 °C. Moreover, PR and EIR vary depending on the three agro-climatic regions of the study area. VECTRI still needs to integrate other aspects of disease transmission, such as population mobility and intervention strategies, in order to be more relevant to support actions of decision-makers and policy makers.

Keywords:  EIR; Global warming; PR; RCA4; VECTRI

DOI:  https://doi.org/10.1007/s00484-022-02388-x
Acta Parasitol. 2022 Oct 19.

Malaria Knowledge-Base and Prevalence of Parasitaemia in Asymptomatic Adults in the Forest Zone of Ghana.

Raymond Charles Ehiem, Bernard Walter L Lawson, John Asiedu Larbi.

   PURPOSE: To determine the levels of knowledge, awareness and perception of malaria, and to determine the infection status among asymptomatic adults in selected districts.
METHODS: This descriptive, cross-sectional study recruited 849 participants from seven districts in the malaria meso-endemic forest zone of Ghana. Questionnaires were administered to elicit responses from asymptomatic adults on malaria awareness, knowledge and insecticide-treated net (ITN) usage. Capillary blood samples were taken from study subjects for malaria Rapid Diagnostic Test (RDT) and microscopy. Descriptive statistics was used to analyse quantitative and qualitative data.
RESULTS: Ninety-eight percent of participants were aware of malaria, 94.0% owned ITNs but only 35.5% consistently used them. Also, 56.7% correctly associated malaria with mosquitoes and 54.5% identified stagnant water as the breeding site. Twelve percent (12.2%) and 13.1% of the subjects tested positive for malaria via RDT and microscopy, respectively. Of the 111 confirmed malaria cases, 107 had Plasmodium falciparum infections, two had Plasmodium ovale infections and there were two Plasmodium falciparum-Plasmodium ovale mixed infections.
CONCLUSION: Awareness and knowledge of malaria was satisfactory but this did not translate into mosquito avoidance behaviour due to deep-seated perceptions and myths. With the prevalence of asymptomatic parasitaemia observed, this reservoir of infection could be dislodged with appropriate health education targeted at women in the rural communities.

Keywords:  Asymptomatic; Malaria; Parasitaemia; Plasmodium

DOI:  https://doi.org/10.1007/s11686-022-00629-y
PLoS Negl Trop Dis. 2022 Oct;16(10): e0010812

The global trends and regional differences in incidence of Zika virus infection and implications for Zika virus infection prevention.

Zirui Guo, Wenzhan Jing, Jue Liu, Min Liu.

BACKGROUND: Zika virus (ZIKV) infection has potential result in severe birth effects. An improved understanding of global trend and regional differences is needed.
METHODS: Annual ZIKV infection episodes and incidence rates were collected from Global Burden of Disease Study 2019. Episodes changes and estimated annual percentage changes (EAPCs) of age-standardized incidence rate (ASR) were calculated. Top passenger airport-pairs were obtained from the International Air Transport Association to understand places susceptible to imported ZIKV cases.
RESULTS: Globally, the ASR increased by an average of 72.85% (95%CI: 16.47% to 156.53%) per year from 2011 to 2015 and subsequently decreased from 20.25 per 100,000 in 2015 to 3.44 per 100,000 in 2019. Most of ZIKV infections clustered in Latin America. The proportion of episodes in Central and Tropical Latin America decreased in 2019 with sporadic episodes elsewhere. High Socio-Demographic Index (SDI) regions had more episodes in 2019 than in 2015. Additionally, 15-49 years group had the largest proportion of episodes, females had a higher number of episodes, and a higher incidence rate of 70 plus group was observed in males than females. Certain cities in Europe, North America and Latin America/Caribbean had a high population mobility in ZIKV outbreak areas considered a high risk of imported cases.
CONCLUSIONS: ZIKV infection is still a public health threat in Latin America and Caribbean and high SDI regions suffered an increasing trend of ZIKV infection. Interventions such as development of surveillance networks and vector-control should be attached to ZIKV control in these key regions. Reproductive suggestions should be taken to reduce ZIKV-related birth defects for the people of reproductive age who are facing a higher threat of ZIKV infection, especially females. Moreover, surveillance of travellers is needed to reverse the uptrends of travel-related imported ZIKV infection. More studies focusing on ZIKV should be performed to make targeted and effective prevention strategies in the future.

DOI: https://doi.org/10.1371/journal.pntd.0010812
Malar J. 2022 Oct 19. 21(1): 293

LLIN Evaluation in Uganda Project (LLINEUP2)-Factors associated with coverage and use of long‑lasting insecticidal nets following the 2020-21 national mass distribution campaign: a cross-sectional survey of 12 districts.

Jaffer Okiring, Samuel Gonahasa, Martha Nassali, Jane F Namuganga, Irene Bagala, Catherine Maiteki-Sebuguzi, Jimmy Opigo, Isaiah Nabende, Joanita Nangendo, Jane Kabami, Isaac Ssewanyana, Steven M Kiwuwa, Joaniter I Nankabirwa, Grant Dorsey, Jessica Briggs, Moses R Kamya, Sarah G Staedke.

   BACKGROUND: In 2020-2021, long-lasting insecticidal nets (LLINs) were distributed nationwide in Uganda during the COVID-19 pandemic. A cross-sectional survey was conducted in 12 districts to evaluate the impact of the campaign 1-5 months after LLIN distribution.
METHODS: During April-May 2021, households were randomly selected from target areas (1-7 villages) surrounding 12 government-run health facilities established as Malaria Reference Centres; at least 50 households were enrolled per cluster. Outcomes included household ownership of LLINs distributed through the universal coverage campaign (UCC) (at least one UCC LLIN), adequate coverage of UCC LLINs (at least one UCC LLIN per 2 residents), and use of LLINs (resident slept under a LLIN the previous night). Multivariate logistic regression models were used to identify household- and individual-level factors associated with outcomes, controlling for clustering around health facilities.
RESULTS: In total, 634 households, with 3342 residents and 1631 bed-nets, were included. Most households (93.4%) owned at least 1 UCC LLIN, but only 56.8% were adequately covered by UCC LLINs. In an adjusted analysis, the factor most strongly associated with adequate coverage by UCC LLINs was fewer household residents (1-4 vs 7-14; adjusted odds ratio [aOR] 12.96, 95% CI 4.76-35.26, p < 0.001; 5-6 vs 7-14 residents; aOR 2.99, 95% CI 1.21-7.42, p = 0.018). Of the 3166 residents of households that owned at least one UCC LLIN, only 1684 (53.2%) lived in adequately covered households; 89.9% of these used an LLIN the previous night, compared to 1034 (69.8%) of 1482 residents living in inadequately covered households. In an adjusted analysis, restricted to residents of inadequately covered households, LLIN use was higher in children under-five than those aged 5-15 years (aOR 3.04, 95% CI 2.08-4.46, p < 0.001), and higher in household heads than distantly-related residents (aOR 3.94, 95% CI 2.38-6.51, p < 0.001).
CONCLUSIONS: Uganda's 2021-21 campaign was successful, despite the COVID-19 pandemic. In future campaigns, strategies should be adopted to ensure high LLIN coverage, particularly for larger households. A better understanding of the drivers of LLIN use within households is needed to guide future interventions, educational messages, and behaviour change communication strategies; school-aged children and distantly-related residents appear vulnerable and could be targeted.

Keywords:  Coverage; Long-lasting insecticidal nets (LLINs); Malaria; Mass distribution campaign; Ownership; Uganda

DOI:  https://doi.org/10.1186/s12936-022-04302-7
Malar J. 2022 Oct 21. 21(1): 294

House screening for malaria control: views and experiences of participants in the RooPfs trial.

Caroline Jones, A Matta, Margaret Pinder, Umberto D'Alessandro, Jakob Knudsen, Steve W Lindsay.

   BACKGROUND: The housing stock of rural sub-Saharan Africa is changing rapidly. With millions of new homes required over the coming decades, there is an opportunity to protect residents by screening homes from malaria mosquitoes. This study, undertaken in the Upper River Region of The Gambia, explores local perceptions of what a good house should provide for its inhabitants and responses to living in a house that has been modified as part of a randomized control trial designed to assess whether improved housing provided additional protection against clinical malaria in children (the RooPfs trial).
METHODS: This descriptive, exploratory study was undertaken over 22 months using mixed-methods (informal conversations, observations, focus group discussions, photovoice, and a questionnaire survey) in a parallel convergent design. Analysis was conducted across the data sets using a framework approach. Following coding, the textual data were charted by a priori and emerging themes. These themes were compared with the quantitative survey results. The nature and range of views about housing and the RooPfs study modifications and the relationships among them were identified and described.
RESULTS: The data were derived from a total of 35 sets of observations and informal conversations in 10 villages, 12 discussions with the photovoice photographers, 26 focus group discussions (across 13 villages) and 391 completed questionnaires. The study participants described a 'good house' as one with a corrugate-metal roof, cement walls (preferably cement block, but mud block covered with cement plaster was also an acceptable and cheaper substitute) and well-fitting doors. These features align with local perceptions of a modern house that provides social status and protection from physical harms. The RooPfs modifications were largely appreciated, although poor workmanship caused concerns that houses had become insecure. However, the long-term trusting relationship with the implementing institution and the actions taken to rectify problems provided reassurance and enhanced acceptability.
CONCLUSION: In developing housing to address population needs in Africa, attention should be paid to local perceptions of what is required to make a house secure for its inhabitants, as well as providing a healthy environment.

Keywords:  Acceptability; Housing; Malaria; Perceptions

DOI:  https://doi.org/10.1186/s12936-022-04321-4
Ann Med Surg (Lond). 2022 Oct;82 104537

Yellow fever outbreak in Kenya: A review.

Olivier Uwishema, Stanley Chinedu Eneh, Anyike Goodness Chiburoma, Wael Atif Fadl Elhassan, Adeniji Abdur-Rahman Adekunle, Martin Sagide Rogose, ElShimaa Zaki, Aymar Akilimali, Helen Onyeaka.

  Yellow fever (YF) is a viral acute hemorrhagic illness caused by infected mosquitoes of the flavivirus family. The first yellow fever outbreak in Kenya was in 1992. Similar outbreaks were recorded in the western part of the country in 1993, 1995, and 2011, particularly in the Rift Valley province of Kenya. In early 2022, the viral acute illness resurfaced and hit Kenya. On January 12, 2022, the first case was discovered, with over 14 patients suffering from fever, jaundice, and joint and muscle pains. On March 4, 2022, a yellow fever outbreak re-emerged in Kenya, affecting 11 wards in Isiolo County. The fatality rate recorded was 11.3% (six deaths), with Chari accounting for 39.6% of the total 21 cases, Cherab 14 (26.4%), and 5 Garba Tulla (9.4%). This has the potential to further endanger the nation's economic growth while also negatively impacting people's daily lives in a part of the world that is already dealing with the catastrophic impacts of the coronavirus pandemic. However, there is no curative therapy for yellow fever. The only options for curbing its spread are through vaccination and preventive measures. Hence, Kenya's government must take responsibility for requiring vaccination of its citizens, implement an active national disease surveillance protocol, and set up anti-yellow fever campaigns in the country.

Keywords:  Africa; COVID-19; Kenya; Outbreak; Virus; Yellow fever

DOI:  https://doi.org/10.1016/j.amsu.2022.104537