Dynamics of Leishmania chagasi infection in small mammals of the undisturbed and degraded tropical dry forests of northern Colombia

Abstract

The infection rate with Leishmania chagasi and the population dynamics of small mammals were studied in an undisturbed forest reserve (Colosó) and an area of highly degraded forest (San Andrés de Sotavento [SAS]) in northern Colombia, both endemic for visceral leishmaniasis. Live trapping of mammals was done every month, and species, age, sex and reproductive status determined. L. chagasi was detected in samples of skin or spleen by the polymerase chain reaction, after extraction of deoxyribonucleic acid using specific primers (DB8/AJS3), and dot blood hybridization. Didelphis marsupialis was found to be infected in Colosó (3/21, 14.3%) and SAS (13/137, 9.5%); its relative abundance was higher in SAS (93/113, 82% of the captures). Although Proechimys canicollis was also found to be infected in Colosó (3/34, 8.8%) and SAS (2/4), its relative abundance was much lower (4%) in SAS than in Colosó (56% of 77 animals captured). Sciurus granatensis, Marmosa robinsoni, Heteromys anomalus, Zygodontomys brevicauda and Metachirus nudicaudatus were less common, and no L. chagasi infection was detected in them.

Transmission, reservoir hosts and control of zoonotic visceral leishmaniasis

“…Unlike the situation in dogs, the vast majority of natural infections in wild mammals appear to be asymptomatic (Table 1). Experimental infections in Didelphis marsupialis and Proechimys semispinosus were also largely asymptomatic (Travi et al 1998(Travi et al b, 2002, though the clinical outcome in experimental infection may depend on the route and dose of infection.…”

Ecology of the Leishmania Species in the Guianan Ecoregion Complex

“…3,8,19,82,101 However, this hypothesis is inconsistent with findings that support the autochthonous origin of this species, which suggest that it was maintained in neotropical canids since the separation of the American and African continents. 6,7,[102][103][104][105][106][107][108] Given this doubt, we will refer to this species as L. (L.) infantum.…”

“…127,128 Some opossums commonly found in the GEC were naturally infected with L. (L.) infantum: Didelphis marsupialis in Columbia [129][130][131] and D. albiventris in Bahia, although foxes and rodents were not infected. 132,133 In Colombia, it was also suggested that the rodent Proechimys canicollis may be a reservoir host of this parasite, 107 but no infection was observed in Proechimys guyanensis after inoculation with a strain from Amazonian Brazil, 134 The status of these marsupial and rodent species as important reservoir hosts for L. (L.) infantum in some specific areas remains unclear.…”

Lutzomyia longipalpis and the eco-epidemiology of American visceral leishmaniasis, with particular reference to Brazil: a review

“…longipalpis was a more sensitive method for detecting infection than was the polymerase chain reaction (PCR). Travi et al (1998b) then studied a variety of small mammals captured in both undisturbed and degraded, dry forest in northern Colombia, using the PCR and dot-blot hybridization techniques: they made no attempt to isolate the parasite. Positive PCR/hybridization results for L. i. chagasi DNA were obtained for 3/21 (14.3%) D. marsupialis caught in undisturbed forest and 13/137 (9.5%) of this animal from the degraded forest.…”

“…No infections with L. i. chagasi were detected in any animal other than the fox C. thous, following the culture of spleen and liver tissue and the inoculation of this material intraperitineally into hamsters. At the time of these studies the PCR/hybridization technique had not been developed and, in view of the finding of Travi et al (1998b) that tissues of wild-caught P. canicollis gave a positive PCR to L. i. chagasi DNA in Colombia, Lainson et al (2002) examined the susceptibility of laboratory-bred P. guyannensis to experimental infection with a canine strain of L. i. chagasi from north Brazil. The animal proved to be totally resistant to infection by way of promastigotes and amastigotes after massive intraperitoneal inoculation of the parasite, and subsequent PCR/hybridization tests made on liver and spleen tissue were negative.…”