Native Rodent Species Are Unlikely Sources of Infection for Leishmania (Viannia) braziliensis along the Transoceanic Highway in Madre de Dios, Peru

Abstract

An estimated 2.3 million disability-adjusted life years are lost globally from leishmaniasis. In Peru's Amazon region, the department of Madre de Dios (MDD) rises above the rest of the country in terms of the annual incidence rates of human leishmaniasis. Leishmania (Viannia) braziliensis is the species most frequently responsible for the form of disease that results in tissue destruction of the nose and mouth. However, essentially nothing is known regarding the reservoirs of this vector-borne, zoonotic parasite in MDD. Wild rodents have been suspected, or proven, to be reservoirs of several Leishmania spp. in various ecosystems and countries. Additionally, people who live or work in forested terrain, especially those who are not regionally local and whose immune systems are thus naïve to the parasite, are at most risk for contracting L. (V.) braziliensis. Hence, the objective of this study was to collect tissues from wild rodents captured at several study sites along the Amazonian segment of the newly constructed Transoceanic Highway and to use molecular laboratory techniques to analyze samples for the presence of Leishmania parasites. Liver tissues were tested via polymerase chain reaction from a total of 217 rodents; bone marrow and skin biopsies (ear and tail) were also tested from a subset of these same animals. The most numerous rodent species captured and tested were Oligoryzomys microtis (40.7%), Hylaeamys perenensis (15.7%), and Proechimys spp. (12%). All samples were negative for Leishmania, implying that although incidental infections may occur, these abundant rodent species are unlikely to serve as primary reservoirs of L. (V.) braziliensis along the Transoceanic Highway in MDD. Therefore, although these rodent species may persist and even thrive in moderately altered landscapes, we did not find any evidence to suggest they pose a risk for L. (V.) braziliensis transmission to human inhabitants in this highly prevalent region.

Leishmania in synanthropic rodents (Rattus rattus): new evidence for the urbanization of Leishmania (Leishmania) amazonensis

“…Neitzke-Abreu et al (2013) tested the accuracy of some PCR-based techniques for CL diagnosis in humans and concluded that the use of blood (buffy coat) may be indicated for patients with no lesions. Our prevalence was higher than reported in other Brazilian (CÁSSIA-PIRES et al, 2014;LARA-SILVA et al, 2014) and foreign studies (LIMA et al, 2002;PAPADOGIANNAKIS et al, 2010;MENDONÇA et al, 2011;SHENDER et al, 2014;VLADIMIR et al, 2015). One study analyzed rodents from waste sites (VLADIMIR et al, 2015) in Croatia; 1/173 (0.5%) rodent (R. rattus) tested positive for L. (L.) infantum; the authors identified five species of phlebotomine sand flies at those places.…”

Distribution and identification of sand flies naturally infected with Leishmania from the Southeastern Peruvian Amazon

“…guyanensis [ 5 , 11 – 13 ]. However, information about Leishmania vectors, reservoirs, their role in disease transmission and the variables influencing their distribution is still limited [ 14 – 16 ]. For instance, a surveillance study using molecular methods for parasite identification, failed to detect Leishmania on more than 80 wild native rodents [ 16 ].…”

Leishmania species in biopsies of patients with different clinical manifestations identified by high resolution melting and nested PCR in an Endemic district in Peru

“…During 1984–1994, this rate increased to 12.69–40.02 people per 100,000 inhabitants, before showing a slight drop and stabilizing during the years 1994–1996 with a mortality rate of approximately 32.45 people per 100,000 inhabitants (Escalante, 1997). One of the zones with the highest rates of annual mortality is, as previously mentioned, Madre de Dios (Shender et al, 2014).…”