3 research outputs found
An entomological survey in the Sudanese Guinean environmental transition zone after indoor residual spraying, Chad
Introduction: malaria is a major public health issue in Africa. In Chad in 2019, with 955,243 confirmed cases and 2,955 deaths, malaria is the main cause of consultations. A longitudinal entomological study was conducted in Moïssala Health District. Its objective was to assess the impact of indoor residual spraying with 80% bendiocarb wettable powder on malaria transmission.
Methods: two areas were defined for the study: Dembo, located in the sprayed area, Moïssala, in the untreated area. Two sampling methods were used: pyrethrum spray catches and human landing catches.
Results: sixteen sessions of human landing catches totalling 32 man-nights were conducted and 160 rooms/site were sprayed. Two anopheles were captured in Dembo and 547 in Moïssala. In Moïssala, An coluzzii, An funestus and An rufipes were captured in the rooms and on human bait. An colluzzii and An funestus were captured in pyrethrum spray catches in Dembo. The anophelian human landing catches density was zero in Dembo while it was 8.38 bites/man/night in outdoor and 10.06 bits/man/night in indoor in Moïssala. Only An coluzzii was found infected in human landing catches and sporozoite index of was 7.46% (10/134) in outdoor and 7.45% (12/161) in indoor in Moïssala. Malaria transmission was estimated at 0.63 infected bites/man/night in outdoor and 0.75 infected bites/man/night in indoor i.e. 229.95 infected bites/man/year in outdoor and 273.75 infected bites/man/year. In pyrethrum spray catches, An coluzzii and An rufipes were the two species found infected in Moïssala with sporozoite indices of 6.70% (23/343) and 20% (2/10) respectively. However, in Dembo, neither of the two captured mosquitoes was found infected.
Conclusion: the indoor residual spraying campaign in the eastern zone of Moïssala has led to the collapse of vectors´ density and aggressiveness. However, its evaluation over a short period of time is not sufficient to assess the impact of malaria transmission in this constant and endemic malaria zone
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Systematic Review of Visceral Leishmaniasis in Central Africa
In underdeveloped countries, infectious diseases remain one of the most important public health challenges. Visceral leishmaniasis, also known as Kala-azar, is a lethal vector-borne parasitic disease with an increasing number of cases. However, it remains one of the most neglected diseases in the world. It is the most severe form of leishmaniasis and is endemic in 75 countries. Around 95% of the patients live in seven countries: Brazil, Ethiopia, India, Kenya, Somalia, South Sudan, and causes about 20,000-40,000 deaths per year of which 50-70% are children. In Central Africa, this pathology is little known and less documented, making it difficult to access information. We have performed this study to characterize the knowledge on the epidemiology of visceral leishmaniasis in Central Africa. We reviewed the literature on visceral leishmaniasis in Central Africa on the number of reported cases, identified parasites, reservoirs and vectors. The documents consulted came from WHO reports, publications of scientific journals, reports of research institutions and abstracts of scientific conferences consulted online on Pubmed and Google Scholar. The information covers the period from the first reporting of cases in each country until December 2020. The review of the situation of visceral leishmaniasis revealed that it is not a significant public health problem in Central Africa. However, a lot of work remains to be done especially surveillance and research in order to present the exact situation of the disease in this part of the continent. This work would include the underreporting of cases inherent to the weaknesses of the surveillance system in these countries, the clarification of the transmission dynamics of human visceral leishmaniasis, canine leishmaniasis, the identity of parasites and vectors
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Distribution and Diversity of Sand Fly Species (Diptera: Psychodidae, Phlebotominae) in Two Geoclimatic Zones of Chad
Leishmaniasis transmitted by sandflies is an important vector-borne disease. In Chad, information on sandflies is outdated, and so this study was designed to update the sandfly fauna. Sandflies were collected in five health districts representing two geoclimatic zones using sticky traps and pyrethrum sprays in indoor and peridomestic habitats between September 2019 and December 2020. All collected sandfly specimens were identified based on species-level morphological characters. A total of 2,015 specimens belonging to 13 species of sandflies (one
Phlebotomus
and twelve
Sergentomyia
) were collected and identified. The vector of human cutaneous leishmaniasis,
Phlebotomus duboscqi
, represents 0.65% of all collected sandflies and is the only representative of the
Phlebotomus
genus to be collected predominantly inside human dwellings.
Phlebotomus orientalis
, the vector of visceral leishmaniasis previously collected in Chad in 1976 was not found in this study.
Sergentomyia clydei, Sergentomyia schwetzi, Sergentomyia antennata
and
Sergentomyia africana
were the most abundant species collected with 44.71%; 22.73%; 16.03% and 11.17%, respectively.
Sergentomyia schwetzi
and
Sergentomyia dubia
, the two species involved in the transmission of canine leishmaniasis, were found in five and four study sites respectively. According to our results, the sandfly fauna of the two geoclimatic zones of Chad is comprised of 13 species. Our data showed that, unlike
P. orientalis
which was not found,
P. duboscqi
is present in four of the five sites surveyed. Therefore, these areas are at risk and remain potential foci of cutaneous leishmaniasis. However, the need for further studies such as vector species detection, their seasonal fluctuations and their vector competence