Dataset Information

Seasonal malaria vector and transmission dynamics in western Burkina Faso.

ABSTRACT: BACKGROUND:In the context of widespread mosquito resistance to currently available pesticides, novel, precise genetic vector control methods aimed at population suppression or trait replacement are a potentially powerful approach that could complement existing malaria elimination interventions. Such methods require knowledge of vector population composition, dynamics, behaviour and role in transmission. Here were characterized these parameters in three representative villages, Bana, Pala and Souroukoudingan, of the Sudano-Sahelian belt of Burkina Faso, a region where bed net campaigns have recently intensified. METHODS:From July 2012 to November 2015, adult mosquitoes were collected monthly using pyrethroid spray catches (PSC) and human landing catches (HLC) in each village. Larval habitat prospections assessed breeding sites abundance at each site. Mosquitoes collected by PSC were identified morphologically, and then by molecular technique to species where required, to reveal the seasonal dynamics of local vectors. Monthly entomological inoculation rates (EIR) that reflect malaria transmission dynamics were estimated by combining the HLC data with mosquito sporozoite infection rates (SIR) identified through ELISA-CSP. Finally, population and EIR fluctuations were fit to locally-collected rainfall data to highlight the strong seasonal determinants of mosquito abundance and malaria transmission in this region. RESULTS:The principal malaria vectors found were in the Anopheles gambiae complex. Mosquito abundance peaked during the rainy season, but there was variation in vector species composition between villages. Mean survey HLC and SIR were similar across villages and ranged from 18 to 48 mosquitoes/person/night and from 3.1 to 6.6% prevalence. The resulting monthly EIRs were extremely high during the rainy season (0.91-2.35 infectious bites/person/day) but decreased substantially in the dry season (0.03-0.22). Vector and malaria transmission dynamics generally tracked seasonal rainfall variations, and the highest mosquito abundances and EIRs occurred in the rainy season. However, despite low residual mosquito populations, mosquitoes infected with malaria parasites remained present in the dry season. CONCLUSION:These results highlight the important vector control challenge facing countries with high EIR despite the recent campaigns of bed net distribution. As demonstrated in these villages, malaria transmission is sustained for large parts of the year by a very high vector abundance and high sporozoite prevalence, resulting in seasonal patterns of hyper and hypo-endemicity. There is, therefore, an urgent need for additional vector control tools that can target endo and exophillic mosquito populations.

SUBMITTER: Epopa PS

PROVIDER: S-EPMC6444393 | biostudies-literature | 2019 Apr

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Seasonal malaria vector and transmission dynamics in western Burkina Faso.

Epopa Patric Stephane PS Collins Catherine Matilda CM North Ace A Millogo Abdoul Azize AA Benedict Mark Quentin MQ Tripet Frederic F Diabate Abdoulaye A

Malaria journal 20190402 1

<h4>Background</h4>In the context of widespread mosquito resistance to currently available pesticides, novel, precise genetic vector control methods aimed at population suppression or trait replacement are a potentially powerful approach that could complement existing malaria elimination interventions. Such methods require knowledge of vector population composition, dynamics, behaviour and role in transmission. Here were characterized these parameters in three representative villages, Bana, Pala ...[more]

PMID: 30940141

Similar Datasets

Project description:BackgroundSeasonal malaria chemoprevention (SMC) is now widely deployed in the Sahel, including several countries that are major contributors to the global burden of malaria. Consequently, it is important to understand whether SMC continues to provide a high level of protection and how SMC might be improved. SMC was evaluated using data from a large, household-randomised trial in Houndé, Burkina Faso and Bougouni, Mali.Methods and findingsThe parent trial evaluated monthly SMC plus either azithromycin (AZ) or placebo, administered as directly observed therapy 4 times per year between August and November (2014-2016). In July 2014, 19,578 children aged 3-59 months were randomised by household to study group. Children who remained within the age range 3-59 months in August each year, plus children born into study households or who moved into the study area, received study drugs in 2015 and 2016. These analyses focus on the approximately 10,000 children (5,000 per country) under observation each year in the SMC plus placebo group. Despite high coverage and high adherence to SMC, the incidence of hospitalisations or deaths due to malaria and uncomplicated clinical malaria remained high in the study areas (overall incidence rates 12.5 [95% confidence interval (CI): 11.2, 14.1] and 871.1 [95% CI: 852.3, 890.6] cases per 1,000 person-years, respectively) and peaked in July each year, before SMC delivery began in August. The incidence rate ratio comparing SMC within the past 28 days with SMC more than 35 days ago-adjusted for age, country, and household clustering-was 0.13 (95% CI: 0.08, 0.20), P < 0.001 for malaria hospitalisations and deaths from malaria and 0.21 (95% CI 0.20, 0.23), P < 0.001 for uncomplicated malaria, indicating protective efficacy of 87.4% (95% CI: 79.6%, 92.2%) and 78.3% (95% CI: 76.8%, 79.6%), respectively. The prevalence of malaria parasitaemia at weekly surveys during the rainy season and at the end of the transmission season was several times higher in children who missed the SMC course preceding the survey contact, and the smallest prevalence ratio observed was 2.98 (95% CI: 1.95, 4.54), P < 0.001. The frequency of molecular markers of sulfadoxine-pyrimethamine (SP) and amodiaquine (AQ) resistance did not increase markedly over the study period either amongst study children or amongst school-age children resident in the study areas. After 3 years of SMC deployment, the day 28 PCR-unadjusted adequate clinical and parasitological response rate of the SP + AQ regimen in children with asymptomatic malaria was 98.3% (95% CI: 88.6%, 99.8%) in Burkina Faso and 96.1% (95% CI: 91.5%, 98.2%) in Mali. Key limitations of this study are the potential overdiagnosis of uncomplicated malaria by rapid diagnostic tests and the potential for residual confounding from factors related to adherence to the monthly SMC schedule.ConclusionDespite strong evidence that SMC is providing a high level of protection, the burden of malaria remains substantial in the 2 study areas. These results emphasise the need for continuing support of SMC programmes. A fifth monthly SMC course is needed to adequately cover the whole transmission season in the study areas and in settings with similar epidemiology.Trial registrationThe AZ-SMC trial in which these data were collected was registered at clinicaltrials.gov: NCT02211729.

Project description:BackgroundTwenty-seven villages were selected in southwest Burkina Faso to implement new vector control strategies in addition to long lasting insecticidal nets (LLINs) through a Randomized Controlled Trial (RCT). We conducted entomological surveys in the villages during the dry cold season (January 2017), dry hot season (March 2017) and rainy season (June 2017) to describe malaria vectors bionomics, insecticide resistance and transmission prior to this trial.MethodsWe carried out hourly catches (from 17:00 to 09:00) inside and outside 4 houses in each village using the Human Landing Catch technique. Mosquitoes were identified using morphological taxonomic keys. Specimens belonging to the Anopheles gambiae complex and Anopheles funestus group were identified using molecular techniques as well as detection of Plasmodium falciparum infection and insecticide resistance target-site mutations.ResultsEight Anopheles species were detected in the area. Anopheles funestus s.s was the main vector during the dry cold season. It was replaced by Anopheles coluzzii during the dry hot season whereas An. coluzzii and An. gambiae s.s. were the dominant species during the rainy season. Species composition of the Anopheles population varied significantly among seasons. All insecticide resistance mechanisms (kdr-w, kdr-e and ace-1 target site mutations) investigated were found in each members of the An. gambiae complex but at different frequencies. We observed early and late biting phenotypes in the main malaria vector species. Entomological inoculation rates were 2.61, 2.67 and 11.25 infected bites per human per month during dry cold season, dry hot season and rainy season, respectively.ConclusionThe entomological indicators of malaria transmission were high despite the universal coverage with LLINs. We detected early and late biting phenotypes in the main malaria vector species as well as physiological insecticide resistance mechanisms. These data will be used to evaluate the impact of complementary tools to LLINs in an upcoming RCT.

Project description:Burkina Faso implemented the seasonal malaria chemoprevention (SMC) in 2014 in seven pilot health districts, following the new recommendation by the WHO in 2012 for the prevention of the disease in children under five years old, for areas of highly seasonal malaria transmission.The objective of this study was to assess the implementation fidelity of the seasonal malaria chemoprevention strategy in one of the districts, Kaya Health District.We conducted a case study, with a quantitative and qualitative mixed methods. Data were collected after two campaigns of implementation of the intervention, in 2014 and 2015, through a review of specific documents of SMC intervention, and individual interview with key informants (n = 21) involved at various levels in the implementation of the strategy and a household survey with the parents (n = 284) of eligible children for the SMC strategy in 2015 in the Kaya health district. The analysis framework focused on the fidelity of the intervention's content, its coverage, and its schedule, as well as the potential moderating factors, using the model proposed by Hasson, originally from Carroll.All components of the intervention were implemented. Villages and sectors were covered at 100%. In terms of intervention doses received, less than one-third of eligible children (32.3%) received the recommended four doses in 2015. Implementation of the strategy faced some difficulties due to insufficient training of community distributors, inadequate supply of inputs and insufficient financial resources for remuneration, advocacy and supervision, but also because of the contextual constraints due to the rainy season. Moreover, an interaction between the different moderating factors, influencing the degree of implementation of the strategy was noted.Taking into account the moderating factors of the implementation is necessary for achieving the highest possible degree of implementation fidelity and then, reach the expected beneficial effects.

Project description:BACKGROUND:Seasonal malaria chemoprevention (SMC) relies on community health workers to distribute drugs. This study assessed: (1) the capacity of community-based distributors (CBDs) at the start and end of a campaign and from one campaign to another after training or refresher courses before each round; (2) to what extent CBDs' experience over several campaigns contributed to measurable increase in their capacities; and (3) to what extent the training and experience of committed CBDs helped the less productive to catch up. METHODS:A longitudinal analysis was conducted in one Burkina Faso health district during the 2017 and 2018 campaigns. A panel including all CBDs was created. Their capacities were observed after: (1) initial training for the 2017 season; (2) refresher training for that year's fourth round; and (3) initial training for the 2018 season. All were invited to complete a questionnaire at the end of training with 27 multiple-choice questions on their main tasks. Observers noted content coverage and conditions under which training sessions were conducted. RESULTS:The 612 CBDs showed, on average, high understanding of their tasks from the start of the annual campaigns. Tasks related to communicating with parents and reporting were best mastered. Their capacities grew from round to round and campaign to campaign, after most had undergone training and been supervised by head nurses. The greatest progress was in the technical components, considered more complex, which involved selecting eligible children, choosing the correct drug packet, and referring children to health professionals. Retaining CBDs from one round to the next benefited everyone, whatever their starting level. Groups that initially obtained the lowest scores (women, illiterates, youngest/oldest) progressed the most. CONCLUSION:These results confirm the potential of using CBDs under routine programme implementation. Mandating CBDs with targeted tasks is a functional model, as they achieve mastery in this context where investments are made in training and supervision. Losing this specificity by extending CBDs' mandates beyond SMC could have undesirable consequences. The added value of retaining committed CBDs is high. It is suggested that motivation and commitment be considered in recruitment, and that a supportive climate be created to foster retention.

Project description:Malaria is a parasitic disease, endemic in many tropical and sub-tropical countries. Malaria is a well-known disease, familiar to almost all people in endemic regions, as they or their family are regularly confronted with it; everyone in these regions has probably experienced the disease, at least once in their life. To investigate the social perceptions of malaria in Burkina Faso, including its diagnosis-driven treatment, we have conducted a survey in both urban (Saint Camille Hospital, Ouagadougou HOSCO) and rural (Boussé Hospital) areas. Fifty-six individuals, mostly representatives of the society variability, were surveyed by questionnaires and 2 focus groups were organized with traditional healers. In general, populations seem to have grasped the causes, symptoms and means of preventing the disease. However, the majority of interviewees make a marked confusion between malaria and dengue; dengue fever is considered like a severe form of malaria. The care modalities (modern and/or traditional medicine) are plural and the choice of therapeutic practice depends on both the socio-economic conditions and education level of the patient. Whereas some patients mark preferences for one type of medicine, others simultaneously recourse to both; for these, a medicine does not outperform the other and their combination multiplies the chances of a quick recovery. Whether for modern or traditional medicine, the diagnosis is considered very important for effective disease management. Modern medicine uses diagnostic tools based on light microscopy and immunochromatography (rapid diagnostic tests; RDT); traditional medicine has its own diagnostic logic but nevertheless recognizes modern medicine diagnosis to guide its therapy. 90 % of those interviewed first use modern medicine to seek an accurate diagnosis of their disease and thus to receive adequate treatment. Presumptive treatments are still widely prescribed and accepted by most patients who trust the judgment of their caregiver, not perceiving any benefit to an objective diagnosis. In front of a negative diagnosis, patient reactions are diverse, some accepting investigations for other diseases (45 %), others opting for self-medication (15 %), others resorting to traditional medicine (20 %). All are unanimous in the importance of diagnosis and are in favor of in-development diagnostic technologies, provided these obviously meet the features of reliability, ease of use, availability and, of course, economical accessibility.

Dataset Information

Seasonal malaria vector and transmission dynamics in western Burkina Faso.

Publications

Seasonal malaria vector and transmission dynamics in western Burkina Faso.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets