One Health: The global challenge of epidemic and endemic leishmaniasis

Abstract

'One Health' proposes the unification of medical and veterinary sciences with the establishment of collaborative ventures in clinical care, surveillance and control of cross-species disease, education, and research into disease pathogenesis, diagnosis, therapy and vaccination. The concept encompasses the human population, domestic animals and wildlife, and the impact that environmental changes ('environmental health') such as global warming will have on these populations. Visceral leishmaniasis is a perfect example of a small companion animal disease for which prevention and control might abolish or decrease the suffering of canine and human patients, and which aligns well with the One Health approach. In this review we discuss how surveillance for leishmaniases is undertaken globally through the control of anthroponootic visceral leishmaniasis (AVL) and zoonotic visceral leishmaniasis (ZVL). The ZVL epidemic has been managed to date by the culling of infected dogs, treatment of human cases and control of the sandfly vector by insecticidal treatment of human homes and the canine reservoir. Recently, preventive vaccination of dogs in Brazil has led to reduction in the incidence of the canine and human disease. Vaccination permits greater dog owner compliance with control measures than a culling programme. Another advance in disease control in Africa is provided by a surveillance programme that combines remote satellite sensing, ecological modelling, vector surveillance and geo-spatial mapping of the distribution of vectors and of the animal-to-animal or animal-to-human pathogen transmission. This coordinated programme generates advisory notices and alerts on emerging infectious disease outbreaks that may impede or avoid the spreading of visceral leishmaniasis to new areas of the planet as a consequence of global warming.

Re-emergence of leishmaniasis in Spain: community outbreak in Madrid, Spain, 2009 to 2012

“…In Spain, dogs are considered to be the main reservoir for L. infantum [1][2][3][4][5][11][12][13]; in this outbreak, only 26% of cases acknowledged contact with dogs in their domestic or peridomestic environment and the cases with dogs as pets in their homes had already applied suitable methods to protect against sandfly bites [3,24]. In order to evaluate the possible presence of vectors, we asked patients about their environment (house, neighbourhood, work, leisure pursuits and holidays).…”

Dificuldades na execução das diretrizes do Programa de Vigilância e Controle da Leishmaniose Visceral em grandes municípios brasileiros

“…Sob o ponto de vista da saúde pública, tem justificativas fundamentadas em alguns fatores: o fato de caninos domésticos serem responsáveis pela dispersão da doença a partir de focos enzoóticos; grande contingente de animais assintomáticos albergando parasitos na derme, com potencial para transmitir a doença; e ainda a constatação de que a doença canina geralmente precede a doença humana 24 . Diversos estudos corroboram a tese defendida pelo PVCLV, uma vez que demonstram que a eutanásia em cães sororeagentes reduz o número de animais infectados e assim a prevalência/incidência humana de LV 25 .…”

“…Em contrário, uma série de outras pesquisas concluiu que não há correlação espacial entre a incidência acumulada de LV humana com a soroprevalência canina, que há ausência de risco significativo de infecção humana na coabitação com cães, que a eutanásia isoladamente não demonstrou vantagem em reduzir a incidência de LV em seres humanos e que existe a possibilidade do envolvimento de outros reservatórios de infecção de L. infantum, tais como pessoas (particularmente crianças desnutridas que podem transmitir para outras crianças), canídeos silvestres e marsupiais 25,26,27,28 .…”

Leishmaniasis: A Review on Parasite, Vector and Reservoir Host

“…The leishmania parasite is transmitted by the bite of infected female sand flies: Phlebotomus in the Old World and Lutzomyia in the New World (central and south America) [56]. The complexity of leishmania transmission lays on its involvement of various mammalian hosts, ranging from small rodents to big domestic animals, as reservoir hosts [57]. Human imposed environmental changes result in the modification of the micro-ecology of the parasite, the vector and the reservoir host favoring the higher transmission of leishmaniasis in areas [58].…”

“…Hence, control and elimination of leishmaniasis largely depends on the understanding of how leishmaniasis involves various mammalian reservoir hosts, whose epidemiological role is yet to be fully understood [60,61]. Epidemiological investigations should not only target human cases, but also focus on animal reservoir and their transmissibility competences [24,57,62,63]. …”