High levels of infectiousness of asymptomatic Leishmania (Viannia) braziliensis infections in wild rodents highlights their importance in the epidemiology of American Tegumentary Leishmaniasis in Brazil.

BACKGROUND: The epidemiological significance of wildlife infections with aetiological agents causing human infectious diseases is largely determined by their infection status, contact potential with humans (via vectors for vector-borne diseases), and their infectiousness to maintain onward transmission. This study quantified these parameters in wild and synanthropic naturally infected rodent populations in an endemic region of tegumentary leishmaniasis in northeast Brazil. METHODS: Capture-mark-recapture (CMR) of rodents was conducted over 27 months in domestic/peri domestic environs, household plantations and nearby Atlantic Forest (9,920 single trap nights). Rodent clinical samples (blood and ear tissue) were tested for infection by conventional PCR and quantitative PCR (qPCR) for Leishmania (Viannia) braziliensis, and xenodiagnosis to measure infectiousness to the local sand fly vector. RESULTS: A total 603 individuals of 8 rodent species were (re)captured on 1,051 occasions. The most abundant species were Nectomys squamipes (245 individuals, 41% of the total catch), Rattus rattus (148, 25%), and Necromys lasiurus (83, 14%). All species were captured in greater relative frequencies in plantations; R. rattus was the only species captured in all three habitats including in and around houses. Four species, comprising 22.6% of individuals captured at least twice, were geolocated in more than one habitat type; 78.6% were infected with L. (V.) braziliensis, facilitating inter-species and inter-habitat transmission. Species specific period prevalence ranged between 0%-62% being significantly higher in N. squamipes (54-62%) and Hollochillus sciureus (43-47%). Xenodiagnosis was performed on 41 occasions exposing 1,879 Nyssomyia whitmani sand flies to five rodent species (37 individuals). Similar mean levels of infectiousness amongst the more common rodent species were observed. Longitudinal xenodiagnosis of the N. squamipes population revealed a persistent level of infectiousness over 13 months follow-up, infecting a median 48% (IQR: 30.1%-64.2%) of exposed blood-fed vectors. The proportion of exposed flies infected was greater in the low compared to in the high seasonal period of vector abundance. L. (V.) braziliensis parasite loads in rodent blood quantified by qPCR were similar across rodent species but did not represent a reliable quantitative marker of infectiousness to sand flies. The standardised risk of rodent infection in plantations was 70.3% relative to 11.3% and 18.4% in peri domestic and forest habitats respectively. R. rattus was the only exception to this trend indicating greatest risk in the peri domestic environment. CONCLUSIONS: The results support the view that a collective assemblage of wild and synanthropic rodent species is an important wild reservoir of L. (V.) braziliensis in this region, with N. squamipes and R. rattus probably playing a key role in transmission within and between habitat types and rodent species. Rodents, and by implication humans, are at risk of infection in all sampled habitats, but more so in homestead plantations. These conclusions are based on one of the longest CMR study of small rodents in an American Tegumentary Leishmaniasis (ATL) foci.

Caracterização da infecciosidade de roedores silvestres e sinantrópicos como hospedeiros reservatórios envolvidos no ciclo zoonótico da leishmaniose tegumentar associada à Leishmania (Viannia) braziliensis / Characterization of infectivity of wild and synanthropic rodents as reservoir hosts involved in the zoonotic cycle of American Cutaneous Leishmaniasis associated with Leishmania (Viannia) braziliensis

Uma das lacunas relacionadas com a ecoepidemiologia da LTA associada à Leishmania (Viannia) braziliensis está relacionada à identificação de hospedeiros reservatórios e flebotomíneos que mantém o ciclo de transmissão. Amaraji, município da Zona da Mata de Pernambuco, apresenta importante incidência da LTA. Este estudo objetivou caracterizar a infecciosidade de roedores silvestres e sinantrópicos à L. (V.) braziliensis como reservatórios envolvidos na manutenção do ciclo zoonótico na região, através do diagnóstico de infecção natural por L. (V.) spp detectado por qPCR (Reação em Cadeia da Polimerase quantitativa); xenodiagnósticos utilizando Lutzomyia longipalpis ou Lutzomyia whitmani em roedores infectados; e, avaliação da interrupção de exposição à transmissão. Estudo experimental realizado entre maio/2012 e agosto/2014, capturou-se 638 roedores pertencentes a 11 diferentes espécies, com predominância de Nectomys squamipes 38,3 por cento (245/638), e, Rattus rattus 23,2 por cento (148/638). Foram marcados com microchips 603 animais, e, realizadas 394 recapturas. Foram obtidos DNA de pele e sangue dos roedores a cada captura/recaptura. Em 176 (29,2 por cento) roedores detectou-se infecção. Foram realizados 51 xenodiagnósticos (46 L. whitmani; 5 L. longipalpis), onde infectaram-se 72,58 por cento (1400/1929) dos flebotomíneos. Não foram identificadas diferenças quanto às espécies vetoras. Roedores foram infectivos aos vetores independentemente da carga parasitária da infecção natural. Foi verificada diminuição da carga parasitária dos roedores em laboratório. A infecção natural por L. (Viannia.) spp detectada nos roedores, indicam que N. squamipes e N. lasiurus atuam como reservatórios primários e, R. rattus, como reservatório secundário no ciclo de transmisssão da LTA na região.

One of the gaps related to ACL (American Cutaneous Leishmaniasis) eco-epidemiology associated with Leishmania (Viannia) braziliensis is related to identification of reservoir hosts and sand flies that keeps the transmission cycle. Amaraji, unicipality of Zona da Mata of Pernambuco state, show a significant incidence of ACL. This study aimed to characterize the infectivity of wild and synanthropic rodents to L. (V.) braziliensis as reservoirs involved in maintaining the zoonotic cycle in the region, through the diagnosis of natural infection with L. (V.) spp detected by qPCR quantitative Reaction Polymerase Chain); xenodiagnoses using fed sandflies (Lutzomyia longipalpisand Lutzomyia whitmani) on infected rodents; and evaluation of exposure to interrupt transmission. Experimental study conducted between may/2012 and august/2014 was captured 638 rodents of 11 various species, with a redominance of Nectomys squamipes 38.3% (245/638), and Rattus rattus 23.2% (148/638). They were markwith microchips 603 rodents, and performed 394 recaptures. DNA samples were obtained from skin and blood of rodents every capt ure / ecapture. In 176 (29.2%) was detected rodents infection. 51 xenodiagnosis were performed (46 use L. whitmaniand 5 use L. longipalpis), where an infected 72.58% (1400/1929) of sand flies. No differences were identified as the vector species. Rodents were infectious to vectors regardless of the load parasite of infection. It was observed decrease in parasite load of laboratory rodents. Natural infection by L. (V.) spp in rodents indicate that N. squamipes and N. lasiurus act as primary reservoirs and R. rattus as secondary reservoir in transmission cycle of LTA in region.

Phlebotomine sandfly species from an American visceral leishmaniasis area in the Northern Rainforest region of Pernambuco State, Brazil.

The aim of this study was to identify the fauna of phlebotomine sandflies in an area with incidence of American visceral leishmaniasis (AVL) in São Vicente Férrer, a municipality (county) located in the northern Zona da Mata in Pernambuco State, Brazil. Sandfly captures were conducted monthly for four nights/month from December 2002 to November 2003, by means of manual captures (with a Shannon trap) and by CDC light traps. A total of 23,156 specimens of phlebotomines sandflies were collected in a remnant of the Atlantic rainforest, houses, and animal shelters. Lutzomyia complexa was the most prevalent species, with a frequency of 62.5% (14,445/23,156), followed by Lutzomyia migonei, with 33.2% (7,677/23,156). No Lutzomyia longipalpis (the main vector of Leishmania chagasi in Brazil and the Americas) was found in the target area. Some specimens were dissected, but no Leishmania parasites were found.

Phlebotomine sandfly species from an American visceral leishmaniasis area in the Northern Rainforest region of Pernambuco State, Brazil

The aim of this study was to identify the fauna of phlebotomine sandflies in an area with incidence of American visceral leishmaniasis (AVL) in São Vicente Férrer, a municipality (county) located in the northern Zona da Mata in Pernambuco State, Brazil. Sandfly captures were conducted monthly for four nights/month from December 2002 to November 2003, by means of manual captures (with a Shannon trap) and by CDC light traps. A total of 23,156 specimens of phlebotomines sandflies were collected in a remnant of the Atlantic rainforest, houses, and animal shelters. Lutzomyia complexa was the most prevalent species, with a frequency of 62.5 percent (14,445/23,156), followed by Lutzomyia migonei, with 33.2 percent (7,677/23,156). No Lutzomyia longipalpis (the main vector of Leishmania chagasi in Brazil and the Americas) was found in the target area. Some specimens were dissected, but no Leishmania parasites were found.

Este estudo teve como objetivo identificar a fauna de flebotomíneos envolvida em área de incidência de leishmaniose visceral americana no Município de São Vicente Férrer, localizado na Zona da Mata de Pernambuco, Brasil. Capturas de flebotomíneos foram realizadas mensalmente durante quatro noites, entre dezembro de 2002 e novembro de 2003, através de capturas manuais com auxílio da armadilha de Shannon e armadilhas luminosas modelo CDC. O total de 23.156 exemplares de flebotomíneos foi coletado em resquícios de Mata Atlântica, casas e abrigos de animais. Lutzomyia complexa apresentou predominância de 62,5 por cento (14.445/23.156), seguida por Lutzomyia migonei, 33,2 por cento (7.677/23.156). Lutzomyia longipalpis, principal vetor de Leishmania chagasi no Brasil e nas Américas, não foi encontrado nesta região. Alguns exemplares foram dissecados para a pesquisa de infecção natural, mas não foram detectadas formas características de Leishmania.