RESUMO O primeiro caso humano autóctone de leishmaniose visceral (LV) na Argentina ocorreu na cidade de Posadas (Misiones) em 2006, desde então, tem ocorrido um aumento na incidência e distribuição geográfica da doença. No período entre 2006 e 2012 foram detectados 107 casos humanos com 11 mortes. Em 2010 se constatou a presença de Lutzomyia longipalpis no município de Puerto Iguazú, localizado na fronteira entre Argentina-Brasil-Paraguai. O presente estudo teve como objetivo investigar a abundância e distribuição de Lu. longipalpis no município de Puerto Iguazú. Lu. longipalpis foi encontrada exclusivamente na área urbana, em 31% das amostras coletadas dos domicílios de referência (n = 53), 67% das quais pertenciam às áreas de baixa abundância, 20% às de moderada e 13% às de alta abundância da espécie. Nyssomyia whitmani foi coletado em ambientes urbanos e periurbanos e Migonemyia migonei, somente nas periferias da cidade. Na atualidade, a cidade de Puerto Iguazú é considerada como de risco moderado; por isso, é necessário intensificar o controle tanto de casos humanos como de caninos e levar em conta as medidas de prevenção e controle do ambiente, dos vetores e dos reservatórios na zona de fronteira Argentina-Brasil-Paraguai.

SUMMARY The first Argentinian autochthonous human case of visceral leishmaniasis (VL) was confirmed in Posadas (Misiones) in 2006. Since then, the disease has increased its incidence and geographical distribution. In the 2006-2012 period, 107 human cases were detected (11 deaths). The presence of Lutzomyia longipalpis was detected in peridomiciles in Puerto Iguazú urban area in 2010; some of these findings were associated with households where cases of canine VL had already been reported. The objective of this study was to ascertain the abundance and spatial distribution of Lu. longipalpis in Puerto Iguazú City, on the Argentina-Brazil-Paraguay border. Lu. longipalpis proved to be exclusively urban and was found in 31% of the households sampled (n = 53), 67% of which belonged to areas of low abundance, 20% to areas of moderate abundance and 13% to areas of high abundance. Nyssomyia whitmani was the only species found both in urban and peri-urban environments, and Migonemyia migonei was registered only on the outskirts of the city. Due to the fact that Puerto Iguazú is considered to be at moderate risk at the moment, it is necessary to intensify human and canine case controls, as well as take integrated prevention and control measures regarding the environment, vectors and reservoirs on the Argentina-Brazil-Paraguay border area.

In this study, a genotypification of Leishmaniawas performed using polimerase chain reaction-restriction fragment length polymorfism (PCR-RFLP) and sequencing techniques to identify species of Leishmaniaparasites in phlebotomine sand flies and dogs naturally infected. Between January-February of 2009, CDC light traps were used to collect insect samples from 13 capture sites in the municipality of Posadas, which is located in the province of Misiones of Argentina. Sand flies identified as Lutzomyia longipalpiswere grouped into 28 separate pools for molecular biological analysis. Canine samples were taken from lymph node aspirates of two symptomatic stray animals that had been positively diagnosed with canine visceral leishmaniasis. One vector pool of 10 sand flies (1 out of the 28 pools tested) and both of the canine samples tested positively for Leishmania infantumby PCR and RFLP analysis. PCR products were confirmed by sequencing and showed a maximum identity with L. infantum. Given that infection was detected in one out of the 28 pools and that at least one infected insect was infected, it was possible to infer an infection rate at least of 0.47% for Lu. longipalpisamong the analyzed samples. These results contribute to incriminate Lu. longipalpis as the vector of L. infantumin the municipality of Posadas, where cases of the disease in humans and dogs have been reported since 2005.

Durante os estádios precoces de transmissão da leishmaniose visceral na cidade de Posadas, Misiones, foi avaliada a atividade noturna da Lutzomyia longipalpis e a atração pelos seres humanos, para fornecer recomendações preliminares. O impacto do inseticida deltametrina peridoméstico, e a borrifação executada por funcionários locais, também foi avaliada. Embora existam Lu. longipalpis atingindo as armadilhas localizadas perto de um cão durante toda a noite, 90% das fêmeas foram capturadas a partir das 20.30h até 1.30h, e só atinge seres humanos quando estão a 1,5 m do cão. A borrifação peridoméstica com deltametrina (25 mg/m²) reduziu a área de captura da mosca da areia, até sete dias após a intervenção, sem dispersão nas bordas das áreas pulverizadas. Estes resultados apóiam as recomendações sobre o tempo-espaço, das medidas de proteção: na primeira metade da noite, no quintal, com animais de estimação criados pelo menos a cinco metros de distância dos seres humanos. A deltametrina como ela é usada, não parece muito eficaz neste cenário, nem o eventual uso de mosquiteiros pelo menos em adultos, devido ao lugar/hora de mais alta atividade de vôo da Lu. longipalpis. Este estudo acentua a necessidade de abordagem multidisciplinar, para desenvolver estratégias de prevenção baseadas tanto em estudos biológicos como antropológicos.

During the earlier stages of visceral leishmaniasis transmission in Posadas City, Misiones, both the night activity and attraction to humans of Lutzomyia longipalpis were assessed, in order to provide preliminary recommendations. The impact of peridomestic deltamethrin spraying performed by local officials was also evaluated. Although Lu. longipalpis were found in traps located over a dog the entire night, 90% of the females were captured from 20.30h to 1.30h, and only landed on a human when he was at a distance of 1.5 m from the dog. Peridomestic spraying of deltamethrin (25 mg/m²) reduced the sand fly capture up to seven days post-intervention without dispersion in the border of the sprayed areas. These results support the recommendations about time-space focus of the protection measures: first half of the night, in the backyard, with pets and domestic animals kept at least 5 m from humans. The deltamethrin as it was used did not seem very effective in this scenario; neither did the eventual use of bed nets, at least in adults, due to the place/hour of sand fly higher activity. This study strengthens the need for a multidisciplinary approach to develop prevention strategies based both on biological and anthropological studies.