Natural Leishmania (Leishmania) mexicana infection and biting activity of anthropophilic sand fly Lutzomyia ayacuchensis in the Ecuadorian Andes.

To elucidate the transmission mode of Andean cutaneous leishmaniasis (Andean-CL), natural Leishmania infection and biting activity of sand flies were tested in a selected sylvatic focus of the endemic area of the Ecuadorian Andes. Monthly sand fly collections and dissections were conducted during 12 months from July 2018 to June 2019. The Leishmania positive specimens/slides with innumerable amounts of actively mobile flagellates made us easy to detect positive sand flies. The promastigotes observed located in the anterior and posterior midgut, without the hindgut localization. The parasite isolated was identified as L. (L.) mexicana by cytochrome b gene analysis. No other Leishmania or flagellate species parasitic in sand flies was observed in the area. Only Lu. ayacuchensis was caught throughout. Monthly microscopic examination of Lu. ayacuchensis revealed 0.75-8.33% of natural L. (L.) mexicana infection rates. Higher Leishmania infection months were present at the end of the wet season of the Andes, while higher sand fly numbers occurred during the dry season. Diurnal biting (blood meal seeking) activity of sand flies started around 17:30 before sunset, increased between 18:00 and 19:30, and thereafter decreased drastically probably because of low temperature (15-18 °C) in the area. The results provide information important for the planning of vector control strategy and management of the disease in the Andean-CL endemic area of Ecuador.

Leishmaniasis caused by Leishmania (Viannia) guyanensis in north-central Pacific region of Ecuador: A clinico-epidemiological feature.

The current four year study was undertaken to investigate the clinical and epidemiological features of Leishmania (Viannia) guyanensis infections in Valle Hermoso, Santo Domingo de Los Tsachilas province, north-central Pacific areas of Ecuador. A total of 155 parasitologically confirmed (Leishmania-amastigote-positive) clinical cases diagnosed at a rural health center during January 2014-December 2017 were analyzed thoroughly. Molecular characterization of the causative Leishmania parasites from different endemic sites within the study areas was performed by PCR amplification of cytochrome b (cyt b) sequencing. All the FTA-card and/or smear impregnated materials tested were characterized, and identified as L. (V.) guyanensis, without detecting any other Leishmania species. The following features were described: 1) the majority of patients were suffered from a single ulcer lesion (simple and mild to chronic), followed by multiple lesions, including recidiva cutis-"like" and Chiclero's ulcer-"like" clinical forms; 2) the majority (65.70%) of lesions were less than 10 mm in size, and distributed mainly on the upper body regions (arm, forearm, face, and neck including ear and head); 3) about 30% (29.68%) of the subjects tested were less than 10 years of age, strongly suggesting the intra- and/or peri-domestic transmission of the disease in the areas. The current clinico-epidemiological feature detected emphasizes the need for further such investigations of the L. (V.) guyanensis infections prevalent at different Pacific ecoregions of Ecuador, including Amazon regions.

An analysis of reported cases of leishmaniasis in the southern Ecuadorian Amazon region, 1986-2012.

An analysis of reported cases of cutaneous leishmaniasis (CL) was performed using the data registered in the southern Ecuadorian Amazon region during 27 years from 1986 to 2012. The cases/subjects with both the suspected CL lesions and the amastigote-positive results were recruited for the analysis. The yearly occurrence of cases showed a markedly higher number during the six years, 1988 and 1993. After 1994 when the insecticide spraying campaign using helicopter in 1993-1994, the number dropped remarkably. Then, the yearly occurrence gradually fluctuated from 101 cases in 1996 to 11 in 2009, maintaining a low number of cases after the campaign. The monthly occurrence of cases showed a markedly high number during March and August, suggesting a correlation to the rainy season (months) in the areas. A statistical significance was found between the monthly average number of the CL case and the average precipitation (p=0.01474). It was suggested that the time of transmission of CL would depend on the rainy seasons at each endemic area of Ecuador, which has a diverse climatic feature depending on the geographic regions. Such information at given leishmaniasis-endemic areas of Ecuador would be important for the future planning of the disease control. Molecular analysis and characterization of clinical samples revealed the presence of Leishmania (Viannia) braziliensis.