Human Asymptomatic Infection in Visceral Leishmaniasis: A Seroprevalence Study in an Urban Area of Low Endemicity. Preliminary Results

Barão, Sandra Cristina; Camargo-Neves, Vera Lucia Fonseca de; Resende, Mariângela Ribeiro; Silva, Luiz J. da

doi:10.4269/ajtmh.2007.77.1051

Cited by 27 publications

(24 citation statements)

References 15 publications

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“…Because our study included all age groups this feature could be an explanation for the high prevalence reported here. Other studies reported similar L. chagasi infection frequencies in regions with both high and low VL endemicities (Barão et al 2007, Romero et al 2009). …”

Section: Discussionsupporting

confidence: 49%

Leishmania infection in humans, dogs and sandflies in a visceral leishmaniasis endemic area in Maranhão, Brazil

Felipe

Aquino

Kuppinger

et al. 2011

Mem. Inst. Oswaldo Cruz

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Visceral leishmaniasis (VL) is considered an important neglected disease that affects many countries of the world (Desjeux 2004). On the American continent, VL is caused by the protozoan parasite Leishmania chagasi, which is transmitted to humans and other vertebrate hosts (e.g., dogs) through the bite of a female sandfly. Lutzomyia longipalpis is considered to be the main vector for VL in Brazil (Lainson & Rangel 2005).A high proportion of L. chagasi infected persons do not present any clinical symptoms of disease, even after a long incubation period (asymptomatic form) (Evans et al. 1992, Romero et al. 2009). Cohort studies in Brazil have described detection of asymptomatic seroconvertors with a sensitive and specific enzyme linked immunosorbent assay (ELISA) test using crude antigens from promastigotes (Badaró et al. 1986a, c) Malnutrition is considered one of the most important factors associated with the development of clinical symptoms of leishmaniasis (Alvar et al. 2006). The high frequency of Leishmania infection found in human beings, dogs and Lu. longipalpis in previous studies in the municipality of Raposa, state of Maranhão (MA), Brazil, may also be associated with poverty (Caldas et al. 2001(Caldas et al. , 2002.Notably, the current knowledge on the epidemiology of VL is mainly based on studies examining the prevalence of Leishmania infections only among humans. There are few studies that simultaneously examine L. chagasi infection across several known hosts and carriers. Therefore, the aim of the present study was to determine the asymptomatic L. chagasi infection rates in human beings, dogs and the vector Lu. longipalpis in the VL endemic area of Raposa. PATIENTS, MATERIALS AND METHODSThe study was performed from August 2006-July 2008 in Vila Maresia, Vila Marisol and Vila Pantoja; all three neighbourhoods are located in the municipality of Raposa situated in the northern coastal region of MA, approximately 28 km from the state capital, São Luis (Figure).In this study, the inclusion criteria for human subjects were the following: living in an endemic area for more than six months, no signs and symptoms of VL (fever for more than 2 weeks, hepatosplenomegaly, weight loss or mucocutaneous pallor) and no previous history of VL. As exclusion criteria, we considered a history of treatment for VL (including treatment failures and relapses), individuals with known immunodeficiency or currently using immunosuppressants and comorbidities (evidence of other conditions leading to splenomegaly, such as schistosomiasis and malaria).In a preliminary census survey, we found 1,417 inhabitants, 986 (70%) of whom participated in the study. This 30% loss was mainly due to internal and external migrations, as well as refusal to participate in the study. Overall, 986 (69.6%) out of 1,417 inhabitants that lived more than six months in the area and did not exhibit clinical VL symptoms participated in the study. From these, 857 individuals (86.9%) were from Vila Maresia, 77 individuals (7.7%) were from Vila Marisol and 52...

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Section: Discussionsupporting

confidence: 49%

Leishmania infection in humans, dogs and sandflies in a visceral leishmaniasis endemic area in Maranhão, Brazil

Felipe

Aquino

Kuppinger

et al. 2011

Mem. Inst. Oswaldo Cruz

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“…Canine visceral leishmaniasis generally precedes human disease in these new areas 4 . This was demonstrated in the visceral leishmaniasis epidemic in Araçatuba, São Paulo State 12,13 . Studies in the State of Rio Grande do Norte show a 32.6% Leishmania infection rate in dogs in an endemic area on the outskirts of the State capital Natal, with a 30% six-month seroconversion rate in these animals.…”

mentioning

confidence: 99%

Forum: geographic spread and urbanization of visceral leishmaniasis in Brazil. Postscript: new challenges in the epidemiology of Leishmania chagasi infection

et al. 2008

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“…17,18 In areas where VL transmission is anthroponotic, asymptomatic persons might play a role as reservoirs, and even in areas where VL is zoonotic it is speculated that these persons could also contribute to transmission. 7,19 Thus, assessment of the prevalence and distribution of asymptomatic cases would contribute to a better understanding of VL transmission and help in developing control efforts.…”

Section: Introductionmentioning

confidence: 99%

Usefulness of the rK39-Immunochromatographic Test, Direct Agglutination Test, and Leishmanin Skin Test for Detecting Asymptomatic Leishmania Infection in Children in a New Visceral Leishmaniasis Focus in Amhara State, Ethiopia

Gadisa¹,

Custodio²,

Cañavate³

et al. 2012

The American Society of Tropical Medicine and Hygiene

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Abstract. In areas where visceral leishmaniasis is anthroponotic, asymptomatically infected patients may play a role in transmission. Additionally, the number of asymptomatic patients in a disease-endemic area will also provide information on transmission dynamics. Libo Kemkem and Fogera districts (Amhara State, Ethiopia) are now considered newly established areas to which visceral leishmaniasis is endemic. In selected villages in these districts, we conducted a study to assess the usefulness of different approaches to estimate the asymptomatic infection rate. Of 605 participants, the rK39 immunochromatographic test was able to detect asymptomatic infection in 1.5% (9 of 605), direct agglutination test in 5.3% (32 of 605), and leishmanin skin test in 5.6% (33 of 589); the combined use of serologic methods and leishmanin skin test enabled detecting asymptomatic infection in 10.1% (61 of 605). We conclude that the best option to detect asymptomatic infection in this new visceral leishmaniasis-endemic focus is the combined use of the direct agglutination test and the leishmanin skin test.

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Human Asymptomatic Infection in Visceral Leishmaniasis: A Seroprevalence Study in an Urban Area of Low Endemicity. Preliminary Results

Cited by 27 publications

References 15 publications

Leishmania infection in humans, dogs and sandflies in a visceral leishmaniasis endemic area in Maranhão, Brazil

Leishmania infection in humans, dogs and sandflies in a visceral leishmaniasis endemic area in Maranhão, Brazil

Forum: geographic spread and urbanization of visceral leishmaniasis in Brazil. Postscript: new challenges in the epidemiology of Leishmania chagasi infection

Usefulness of the rK39-Immunochromatographic Test, Direct Agglutination Test, and Leishmanin Skin Test for Detecting Asymptomatic Leishmania Infection in Children in a New Visceral Leishmaniasis Focus in Amhara State, Ethiopia

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