American visceral leishmaniasis (AVL) is considered a zoonotic disease caused by Leishmania (Leishmania) infantum chagasi. It is distributed in the Americas, including some large emerging foci in the Brazilian Amazon region; in Brazil, it has been recorded in most states with different geographical regions1) (2) (3.
The Guianan Ecoregion Complex (GEC) comprises particular ecologic areas from the Guiana Shield within the Amazon biome, which covers Western Venezuela, Northern Brazil, Guyana, Suriname, and French Guiana. In the GEC, cases of autochthonous AVL have been registered, mainly in Venezuela and Brazil (the Northern Pará and Roraima States) where there have also been official reports about the vector Lutzomyia longipalpis. Doubtful sporadic AVL occurrence in Suriname and the absence of vector information in AVL focus of Guyana has drawn attention for the need to further investigate these areas4.
On the basis of this epidemiological background, we present communication aimed to discuss early and current data about the occurrence of the AVL sand fly vector and reservoir host in Amapá, Brazil, to highlight this importance for the ecology of AVL in the Brazilian Guianan-Amazon biome, and to draw attention to Brazilian and international public health issues.
Since the 1950s when the first clinical-entomological survey on American cutaneous leishmaniasis (ACL) was conducted in Amapá5) (6, few studies have been published about sand fly fauna, and until recently, only vectors of ACL have been found7. The first occurrence of L. longipalpis, however, was reported in 2013 during activities of a vector monitoring program for a hydroelectric system placed in the municipality of Ferreira Gomes; specimens were captured in a rural environment closely associated with peri domiciliar areas with dog shelters8. In subsequent captures, including a recent one made during November 2015, this sand fly species still seemed to be very frequent in the same environments. It can be speculated that the lack of entomological investigations in other municipalities eco-geographically close to Ferreira Gomes may be bias to the underreporting of the distribution of L. longipalpis in Amapá. Moreover, L. longipalpis was found to be associated with chicken shelters in the municipality of Almeirim (Pará) near from the municipality of Laranjal do Jari (Amapá) (AKR Galardo: personal observation). This latter region has only been associated with the epidemiology of ACL9. However, it is important to note areas that have been recently investigated, including some areas in Amapá: Serra do Navio, Laranjal do Jari (a hydroelectric system impacted area), Ferreira Gomes [FLOresta NAcional (FLONA) do Amapá; (National Forest of Amapá)] and Oiapoque where until now, L. longipalpis is apparently absent (AKR Galardo and TV Santos: unpublished observations). These surveys will be a subject of future publications from our group.
The natural reservoir of Leishmania (Leishmania) infantum chagasi, the crab-eating fox Cerdocyon thous, was unknown to be present in Amapá, despite its known widespread presence in South America. However, the distribution of this mammal has been updated since it has been found in savannas near the municipalities of Ferreira Gomes and Porto Grande (Matapi River) and in the terra-firme forest near the Macapá municipality (environmental protected area – APA Curiaú)10. Later, a camera-trap study conducted in Cabo Orange National Park registered this species in the savannas near Cassiporé River (Calçoene municipality)11.
Considering the vector-reservoir information, it must be highlighted that these data may represent an increasing risk of the establishment of the AVL transmission cycle in Amapá. In a closely geographically related territory of French Guiana, a canine case of visceral leishmaniasis was reported as imported from the Old World. Interestingly, a supposed sexual transmission to a native dog has been proven, as this fact was considered based on sustaining the hypothesis of intercontinental dispersion of this parasite (assumed as L. infantum); however, until now, no autochthonous cases have been documented since the vector L. longipalpis is still absent from that territory12.
Nevertheless, the close relationship between Amapá and French Guiana because of human activities may probably act as a bridge for vector dispersion. In Brazil, the geographic spread of AVL is historically recognized13, and different transmission profiles may be emerging in strategic areas such as the international borders14. Further studies on populations of L. longipalpis from these emerging foci could improve the understanding of the origins of putative vector dispersion in the Guianan-Amazon leishmaniasis region.
The recommended epidemiological surveillance of the Programa de Vigilância e Controle da Leishmaniose Visceral(Visceral Leishmaniasis Surveillance and Control Program) by the Ministry of Health in Brazil plans to incorporate silent areas (without records of human and/or canine cases of AVL) for surveillance actions to avoid or minimize possible impacts of the disease in new areas14. Thus, regarding Amapá, a further canine survey in areas with the occurrence of L. longipalpis is an important step to continuing the entomological survey.