Infecção natural por tripanosomatídeos (Kinetoplastida: Trypanosomatidae) em Lutzomyia umbratilis (Diptera: Psychodidae) em áreas de leishmaniose tegumentar americana no Amazonas, Brasil

Durante o período de 2002 a 2003 foram realizadas coletas de flebotomíneos em duas áreas do estado do Amazonas (Base de treinamento militar - BI1 e Tarumã Mirim). Nessas coletas foram capturadas um total de 1.440 fêmeas de Lutzomyia (Nyssomyia) umbratilis. Lu.umbratilis é a principal responsável pela transmissão da Leishmaniose Tegumentar Americana (LTA) ao norte do Rio Amazonas. Do total coletado apenas 15 espécimens (ou 1,04%) apresentaram infecção natural por tripanosomatídeos, sendo 12 na BI1 e 3 em Tarumã-Mirim. Isso representou uma taxa de infecção de 1,66% (12 dos 720 capturados em BI1) e 0,42% (3 dos 720 em Tarumã-Mirim). Estes resultados confirmam as informações prévias por outros autores de reduzidos valores de infecção natural por tripanosomatídeos em flebotomíneos, mesmo em áreas altamente endêmicas para leishmaniose.During the period of 2002 to 2003, there were collected sand flies in two areas of Amazon State (Forest Combat Training Base - BI1 and Tarumã-Mirim). Were collected the 1440 L. (Nyssomyia) umbratilis female. Lu. umbratilis is the main responsible for the transmission of American Tegumentary Leishmaniasis (ATL) in the northern of Amazon River. Only 15 specimens (or 1,04%) presented natural infection with trypanosomatids, being 12 at Bl1 and 3 at Tarumã-Mirim. The infection rate was 1,66% (12 of the 720 collected at BI1) and 0,42% (3 of the 720 at Tarumã-Mirim). These results confirm the previous informations described by other authors that insects have low rates of natural infection by trypanosomatids even in high endemic areas for Leishmaniasis

Meat Feeding Restricts Rapid Cold Hardening Response and Increases Thermal Activity Thresholds of Adult Blow Flies, Calliphora vicina (Diptera: Calliphoridae)

Virtually all temperate insects survive the winter by entering a physiological state of reduced metabolic activity termed diapause. However, there is increasing evidence that climate change is disrupting the diapause response resulting in non-diapause life stages encountering periods of winter cold. This is a significant problem for adult life stages in particular, as they must remain mobile, periodically feed, and potentially initiate reproductive development at a time when resources should be diverted to enhance stress tolerance. Here we present the first evidence of protein/meat feeding restricting rapid cold hardening (RCH) ability and increasing low temperature activity thresholds. No RCH response was noted in adult female blow flies (Calliphora vicina Robineau-Desvoidy) fed a sugar, water and liver (SWL) diet, while a strong RCH response was seen in females fed a diet of sugar and water (SW) only. The RCH response in SW flies was induced at temperatures as high as 10°C, but was strongest following 3h at 0°C. The CTmin (loss of coordinated movement) and chill coma (final appendage twitch) temperature of SWL females (-0.3 ± 0.5°C and -4.9 ± 0.5°C, respectively) was significantly higher than for SW females (-3.2 ± 0.8°C and -8.5 ± 0.6°C). We confirmed this was not directly the result of altered extracellular K+, as activity thresholds of alanine-fed adults were not significantly different from SW flies. Instead we suggest the loss of cold tolerance is more likely the result of diverting resource allocation to egg development. Between 2009 and 2013 winter air temperatures in Birmingham, UK, fell below the CTmin of SW and SWL flies on 63 and 195 days, respectively, suggesting differential exposure to chill injury depending on whether adults had access to meat or not. We conclude that disruption of diapause could significantly impact on winter survival through loss of synchrony in the timing of active feeding and reproductive development with favourable temperature conditions

The epidemiology of dermal leishmansiasis in British Honduras: III. The transmission of Leishmania mexicana to man by Phlebotomus pessoanus, with observations on the development of the parasite in different species of Phlebotomus (Publicado originalmente em 1966)

London School of Hygiene and Tropical Medicine. Department of Parasitology. Keppel St., London, W.C.London School of Hygiene and Tropical Medicine. Department of Parasitology. Keppel St., London, W.C / Ministério da Saúde. Fundação Serviço Especial de Saúde Pública. Instituto Evandro Chagas. Laboratório de Vírus de Belém. Belém, PA, Brasil.During 1960-62 a study on the epidemiology of dermal leishmaniasis due to Leishmania mexicana in British Honduras revealed 18 species of Phlebotomus in the enzootic forest areas. In addition, seven other sandflies remain to be identified and may represent new species. Nine species of Phlebotomus were found commonly to bite man. All were predominantly nocturnal in their feeding habits and, as they were readily infected with L. mexicana, all must be regarded as potential vectors in nature. The infection rates for sandflies fed directly on hamster lesions, at the periphery, and on normal adjacent skin were 95%, 48% and 0% respectively. Maintenance of wild-caught Phlebotomus species is discussed. Best results were obtained by keeping single flies in corked tubes containing a fresh green leaf. The corks had a groove cut throughout their length, to allow air exchange, and all tubes were kept in constant light and at approximately 100% relative humidity. Three hundred and thirty-two sandflies, including all the known man-biting species from British Honduras, were fed on the lesions of hamsters and mice infected with both human and rodent strains of L. mexicana. Fifty-two flies were induced to re-feed on volunteers (eight fed a second time and one a third time), in all inflicting a total of 90 probes. Transmission of L. mexicana to man was achieved, by Phlebotomus pessoanus, on one occasion. This insect had fed on the infected hamster only three days and 23 hours previously. The development of L. mexicana in the insect host has been followed by a study of the gut contents and sections of entire sandflies which were fixed at three, six, 12, 24, 36, and 48 hours and 3- 5 days after their infective feed. The development is to an anterior station, the leptomonads reaching the proboscis as early as four days after the infecting blood meal. Four hundred and thirty-nine wild-caught female sandflies were dissected in an attempt to find insects naturally infected with L. mexicana. Flagellates were seen in the hind-gut of one specimen of P. ovallesi and others in the crushed gut from a single P. cruciatus (exact position in the gut uncertain). In the absence of animal inoculation the nature of these flagellates remains uncertain, but they are not thought to be leptomonads of L. mexicana. Attempts to demonstrate mechanical transmission of L. mexicana were made by interrupting sandflies feeding on hamster lesions and immediately allowing such insects to renew feeding on volunteers. No transmission was achieved and it is felt that such a mode of transfer plays little or no part in the transmission of the parasite in nature. On the contrary, the killing and squashing of infected sandflies feeding on human skin may well facilitate entry of the parasite. Although sandflies were successfully infected with L. mexicana after feeding on a newly acquired and non-ulcerative human lesion, man-to-man transmission is considered most unlikely in nature