Diversity of Sand Flies (Diptera: Psychodidae: Phlebotominae) in Two Different Eco-Climatic and Endemic Zones of Cutaneous Leishmaniasis in Mali, West Africa

Molecular identification of phlebotomine sand flies and the harbored Leishmania spp. in Sokoto State, Nigeria

Introduction

Female sand flies are hematophagous, feeding on animals and in the process serve as vectors for Leishmania, the parasites that cause leishmaniasis in humans. Leishmaniasis are a group of parasitic neglected tropical diseases in 98 countries including Nigeria and kills ~60,000 people/year. In Nigeria, Sokoto State is endemic to leishmaniasis but there is a knowledge gap on the identity of the prevalent sand flies and the Leishmania species they transmit. Hence, this cross-sectional study was designed to take inventory of the species of sand flies in Sokoto using genetic methods.

Methods

1,260 (310 females) sand flies were collected from three Local Government Areas (L.G.A) of Sokoto State- Wamakko, Sokoto South and Kware. Genomic DNA was extracted from each fly and DNA amplification by polymerase chain reaction (PCR) was carried out on the DNA samples using primers targeting the arthropods mitochondrial cytochrome oxidase subunit 1 (mt-coI) gene, and nested PCR with primers targeting the gene for Leishmania internal transcribed spacer-1 (its-1) of ribosomal RNA its-1rRNA. The PCR products were sequenced.

Results

Gene sequence analysis revealed five species of sand flies belonging to the old-world genera namely Phlebotomus and Sergentomyia. The identified species were P. papatasi (6.45%), S. adleri (6.45%), S. affinis (9.7%), S. distincta (9.7%), S. schwetzi (67.7%). Within the sampling period, sand flies were most abundant in the rainy months of August (104/33.5%) and September (116/37.4%) with all the five identified species occurring. Sequence analysis of its-1 gene identified Leishmania infantum in two sand flies (2/310)- P. papatasi (from Sokoto South) and S. affinis (from Wamakko). BLAST search in NCBI and phylogenetic analysis revealed that the sand fly species are related to the species reported in different parts of Africa, while the L. infantum is identical to strain reported in Brazil (KY379083.1).

Discussion

Phlebotomus papatasi and four species belonging to the genus Sergentomyia are the most prevalent sand flies in Sokoto State, Nigeria and they harbor L. infantum solely. The results shed light on why visceral leishmaniasis is the most predominant form of the disease. Therefore, we recommend that adequate care for dogs must be instituted as dogs are the major animal reservoir for L. infantum.

Molecular detection of Leishmania (Sauroleishmania) adleri (Trypanosomatida: Trypanosomatidae) in Sergentomyia sp. sand flies (Diptera: Psychodidae) in Mali and Niger

Phlebotomine sand flies of the genus Sergentomyia are considered to be of minor importance as vectors of Leishmania parasites pathogenic to humans, but are known to transmit lizard parasites of the subgenus Sauroleishmania, including L. (S.) adleri. However, knowledge on the geographic distribution of Sauroleishmania spp. and the infection rates in the vectors is very limited. Therefore, our study aimed (1) to further elucidate the distribution and prevalence of Sauroleishmania spp. in their respective vectors and (2) to assess the potential risk for occasional transmission of Leishmania parasites to international military personnel deployed in camps in Mali and Niger. A total of 1,482 wild-caught sand flies (Sergentomyia spp. and closely related Grassomyia spp.) were screened by real-time PCR for the presence of Leishmania DNA. Thirty-two sand fly pools were tested positive, with six from Mali and 26 from Niger. The DNA of four representative isolates was sequenced. The resulting sequences revealed a homology to L. adleri, which leads to the first report of this species from Mali and Niger to the best of our knowledge. The results suggest that Sergentomyia (Sintonius) clydei might be the natural sand fly vector, while Grassomyia spp. appear to be refractory. No Leishmania sp. pathogenic to humans was detected in these sand flies.

Ecological site distribution of sand fly species of Mokolo, an endemic focus of cutaneous leishmaniasis in northern Cameroon

Leishmaniasis is a vector borne disease present in two major clinical forms (cutaneous and visceral) in the northern part of Cameroon. The disease is classified as a neglected tropical disease by the World Health Organization and thus, requires more attention. The aim of this study was to correlate the previously established composition and abundance of sand fly fauna with the putative vector status and the ecological behavior in the Mokolo cutaneous leishmaniasis focus to propose fighting strategies integrating vectors control. Over a 12-month period light traps were used for sand flies' collection in urban, peri-urban and sylvatic environment found in Mokolo, an endemic focus of leishmanisis in northern Cameroon, microscope and taxonomic keys were used for their identification. Nineteen (19) species were identified belonging to the genera Sergentomyia, and Phlebotomus. The influence of human population density on sand fly's species density and composition was assessed trough the evaluation of ecological distribution of sand flies in Mokolo. It came out that, Se. coronula and Se. thomsoni mandarai are strictly wild species and Ph. duboscqi, a domestic species. The other species are generalists.The number of Se. antennata and Se. adami decreases with the increase of the density of human population while Se. distincta, Se. vorax and Ph. duboscqi increase with the density of human population in the study site. Based on its previous reports in the Leishmania transmission in West Africa, Ph. duboscqi should still be considered as the main suspected vector in Mokolo. Ph. duboscqi, Se. distincta, Se. affinis ssp. vorax and Se. schwetzi are highly represented around human dwellings.

Evaluation of Household Preparedness and Risk Factors for Cutaneous Leishmaniasis (CL) Using the Community Assessment for Public Health Emergency Response (CASPER) Method in Pakistan

(1) Background: In endemic areas of Pakistan, local community knowledge and attitudes towards cutaneous leishmaniasis (CL) are critical elements in the effective control and management of the disease. A cross-sectional epidemiologic design was used to assess the disease concern, preparedness, practices, and preventive behavior of the households and to assist the personnel and health care professionals in strengthening their planning efforts and awareness of CL. (2) Methods: A two-stage cluster sampling process, i.e., Community Assessment for Public Health Emergency Response (CASPER) was conducted from September 2020 to March 2021 on present household-level information about community needs and health status regarding CL in a cost-effective, timely, and representative manner. (3) Results: In the current study, 67% of the respondents were aware of CL and its causative agent and showed a low level of pandemic preparedness. The majority (74%) of the respondents mentioned that they did not avoid sandfly exposure areas. The majority (84%) of respondents had unsatisfactory behavior towards using bed nets, sprays, or repellents. (4) Conclusion: In endemic areas of Pakistan, the inadequate concern and low preparedness of the local community toward CL are critical aspects in efficient control and management of the disease.

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.

Inventory and taxonomy of phlebotomine sand flies of the Mokolo leishmaniasis focus, northern Cameroon, with description of new Sergentomyia taxa (Diptera: Psychodidae)

Leishmaniasis is endemic in northern Cameroon. However, the sand fly vectors have not been incriminated. A sand fly species inventory was generated by integrating a number of techniques. Miniature light traps were used for collecting sand flies in a variety of ecotopes found across the area, and a morphological and molecular identification approach for taxonomic confirmation was undertaken. In a pilot survey conducted in September 2012, we captured 687 sand flies, 259 of which were morphologically identified to species level. They represent 14 species of the genera Sergentomyia and Grassomyia. No Phlebotomus spp. were found. A second series of collections was carried out during 2013 in five different environmental setups: two urban, two peri-urban/rural and one sylvatic; 14,036 sand flies (6665 males and 7371 females) were collected. A total of 5926 females and 98 males were morphologically identified to species level, representing 19 species of the genera Sergentomyia, Grassomyia and Phlebotomus, including Ph. duboscqi, a known vector of cutaneous leishmaniasis in the region. Two new taxa were found and are described: Sergentomyia (Sintonius) thomsoni mandarai ssp. nov. and Se. coronula sp. nov. Our study is the first to report the following species in Cameroon: Se. (Sin.) thomsoni (as ssp. nov. mandarai), Se. (Ser.) cincta, Se. (Sin.) affinis ssp. vorax, Se. (Sin.) adami, Se. (Sin.) herollandi, and Se. (Sin.) christophersi. In addition, some morphologically atypical Sergentomyia specimens (combination of Ser. x Sin. traits) were recorded. A checklist of 32 species reports from Cameroon is presented.

Prevalence of Cutaneous Leishmaniasis in Districts of High and Low Endemicity in Mali

Historically the western sahelian dry regions of Mali are known to be highly endemic for cutaneous leishmaniasis (CL) caused by Leishmania major, while cases are rarely reported from the Southern savanna forest of the country. Here, we report baseline prevalence of CL infection in 3 ecologically distinct districts of Mali (dry sahelian, north savanna and southern savanna forest areas). We screened 195 to 250 subjects from 50 to 60 randomly selected households in each of the 6 villages (four from the western sahelian district of Diema in Kayes region, one from the central district of Kolokani and one from the southern savanna district of Kolodieba, region of Sikasso). The screening consisted of: 1] A Leishmanin Skin Test (LST) for detection of exposure to Leishmania parasites; 2] clinical examination of suspected lesions, followed by validation with PCR and 3] finger prick blood sample to determine antibody levels to sand fly saliva. LST positivity was higher in the western district of Diema (49.9%) than in Kolokani (24.9%) and was much lower in Kolondieba (2.6%). LST positivity increased with age rising from 13.8% to 88% in Diema for age groups 2-5 years and 41-65 years, respectively. All eight PCR-confirmed L. major CL cases were diagnosed in subjects below 18 years of age and all were residents of the district of Diema. Exposure to sand fly bites, measured by anti-saliva antibody titers, was comparable in individuals living in all three districts. However, antibody titers were significantly higher in LST positive individuals (P<0.0001). In conclusion, CL transmission remains active in the western region of Mali where lesions were mainly prevalent among children under 18 years old. LST positivity correlated to higher levels of antibodies to sand fly salivary proteins, suggesting their potential as a risk marker for CL acquisition in Mali.