Studies on new world Leishmaniasis and its transmission, with particular reference to Ecuador

Yoshihisa Hashiguchi : Representative of the Overseas Scientific Research Teamfunded by the Ministry of Education , Science & Culture , Japa

Studies on new world Leishmaniasis and its transmission, with particular reference to Ecuador

Yoshihisa Hashiguchi : Representative of the Overseas Scientific Research Teamfunded by the Ministry of Education , Science & Culture , Japa

Detection and identification of Leishmania species within naturally infected sand flies in the Andean areas of Ecuador by a polymerase chain reaction

The surveillance of prevalent Leishmania and sand fly species in endemic areas is important for prediction of the risk and expansion of leishmaniasis. In this study, we developed a polymerase chain reaction (PCR)-based method for detection of Leishmania minicircle DNA within individual sand flies. Using this method, we detected minicircle DNA in 6 (3.3%) of 183 sand flies, while 5 (3.5%) of 143 were positive for Leishmania promastigotes in the same areas by microscopic examination. The species were identified as Leishmania (Leishmania) mexicana by nucleotide sequencing of the cytochrome b gene. Additionally, all the Leishmania-positive sand flies were identified as Lutzomyia ayacuchensis by the restriction enzyme digestion of the PCR-amplified 18S ribosomal RNA gene fragments. Since this combined method is relatively easy and can process a large number of samples, it will be a powerful tool for the rapid identification of prevalent sand fly and Leishmania species as well as monitoring the infection rate in sand fly populations in endemic areas.Fil: Kato, Hirotomo. Yamaguchi University; JapónFil: Uezato, Hiroshi. University of the Ryukyus; JapónFil: Katakura, Ken. Hokkaido University; JapónFil: Calvopina, Manuel. Kochi University. Kochi Medical School; JapónFil: Marco, Jorge Diego. Kochi University. Kochi Medical School; Japón. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Patología Experimental. Universidad Nacional de Salta. Facultad de Ciencias de la Salud. Instituto de Patología Experimental; ArgentinaFil: Barroso, Paola Andrea. Kochi University. Kochi Medical School; Japón. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Patología Experimental. Universidad Nacional de Salta. Facultad de Ciencias de la Salud. Instituto de Patología Experimental; ArgentinaFil: Gomez, Eduardo. Universidad Católica de Guayaquil; EcuadorFil: Mimori, Tatsuyuki. Kumamoto University; JapónFil: Korenaga, Masataka. Kochi University. Kochi Medical School; JapónFil: Iwata, Hiroyuki. Yamaguchi University; JapónFil: Nonaka, Shigeo. University ok the Ryukyus; JapónFil: Hashiguchi, Yoshihisa. Kochi University. Kochi Medical School; Japó

Natural infection of the sand fly Phlebotomus kazeruni by Trypanosoma species in Pakistan

The natural infection of phlebotomine sand flies by Leishmania parasites was surveyed in a desert area of Pakistan where cutaneous leishmaniasis is endemic. Out of 220 female sand flies dissected, one sand fly, Phlebotomus kazeruni, was positive for flagellates in the hindgut. Analyses of cytochrome b (cyt b), glycosomal glyceraldehyde phosphate dehydrogenase (gGAPDH) and small subunit ribosomal RNA (SSU rRNA) gene sequences identified the parasite as a Trypanosoma species of probably a reptile or amphibian. This is the first report of phlebotomine sand flies naturally infected with a Trypanosoma species in Pakistan. The possible infection of sand flies with Trypanosoma species should be taken into consideration in epidemiological studies of vector species in areas where leishmaniasis is endemic

Duration of blood feeding of Simulium ochraceum in relation to intake of Onchocerca volvulus microfilariae

金沢大学留学生センターグアテマラにおけるオンコセルカ症の主要媒介種Simulium ochraceumのOnchocerca volvulus仔虫のとりこみに関して実験を行った。仔虫のとりこみは, ブユが体表にとまってから30秒で始まった。3∿4分後には65%のブユが吸血を完了し, とりこまれる仔虫数が最高に達した。それ以後は吸血時間がのびても, とりこみ量は増加しなかった。仔虫密度が皮膚10(mm)^2あたり55∿116匹の中程度に感染した人にあっては, とりこまれる仔虫の数は皮膚中の仔虫の密度と関連していた。しかし仔虫密度が1.8と非常に低い人の場合に, 異常に高い仔虫のとりこみが観察された。このことは, 皮膚中の仔虫密度が低い場合には, 仔虫がブユの吸血時に誘引あるいは何らかの刺激を受けることを示唆するものかもしれない。 Intake of microfilariae of Onchocerca volvulus by Simulium ochraceum, the main vector of onchocerciasis in Guatemala, was studied. The initiation of intake of microfilariae was around 30sec after landing. Thereafter, the number of microfilariae taken by flies increased as the feeding time increased. After 3 to 4min of landing, 69% of flies finished their blood meal, and the intake of microfilariae reached the highest. Thereafter, increase of feeding time did not increase the intake. With the volunteers of moderate density of microfilariae (55-116 Mf per 10(mm)^2), the number of microfilariae taken by the flies was correlated with the density of microfilariae in human skin. With a volunteer of very low density (1.8 Mf per 10(mm)^2), however, an extraordinarily high intake of microfilariae was observed. This suggested the possibility of the flies attracting or stimulating the microfilariae in the skin of low density carriers

Leishmania isoenzyme polymorphisms in Ecuador: Relationships with geographic distribution and clinical presentation

Background: Determinants of the clinical presentation of the leishmaniases are poorly understood but Leishmania species and strain differences are important. To examine the relationship between clinical presentation, species and isoenzyme polymorphisms, 56 Leishmania isolates from distinct presentations of American tegumentary leishmaniasis (ATL) from Ecuador were analyzed. Methods: Isolates were characterized by multilocus enzyme electrophoresis for polymorphisms of 11 isoenzymes. Patients were infected in four different ecologic regions: highland and lowland jungle of the Pacific coast, Amazonian lowlands and Andean highlands. Results: Six Leishmania species constituting 21 zymodemes were identified: L. (Viannia) panamensis (21 isolates, 7 zymodemes), L. (V.) guyanensis (7 isolates, 4 zymodemes), L. (V.) braziliensis (5 isolates, 3 zymodemes), L. (Leishmania) mexicana (11 isolates, 4 zymodemes), L. (L.) amazonensis (10 isolates, 2 zymodemes) and L. (L.) major (2 isolates, 1 zymodeme). L. panamensis was the species most frequently identified in the Pacific region and was associated with several clinical variants of cutaneous disease (CL); eight cases of leishmaniasis recidiva cutis (LRC) found in the Pacific highlands were associated with 3 zymodemes of this species. Mucocutaneous leishmaniasis found only in the Amazonian focus was associated with 3 zymodemes of L. braziliensis. The papular variant of CL, Uta, found in the Andean highlands was related predominantly with a single zymodeme of L. mexicana. Conclusion: Our data show a high degree of phenotypic variation within species, and some evidence for associations between specific variants of ATL (i.e. Uta and LRC) and specific Leishmania zymodemes. This study further defines the geographic distribution of Leishmania species and clinical variants of ATL in Ecuador