Atypical cutaneous leishmaniasis cases display elevated antigen-induced interleukin-10.

In humans, Leishmania chagasi parasites can produce subclinical infections, atypical cutaneous leishmaniasis (ACL) and visceral leshmaniasis that is potentially fatal if not treated in a timely fashion. L. chagasi parasites that cause both ACL and visceral disease appear to be genetically similar, which suggests that host factors such as the immune response play an important role in controlling infection. We evaluated the immunologic response in ACL using peripheral blood mononuclear cells (PBMCs) of 37 subjects divided into three groups: (i) active ACL cases, (ii) asymptomatic cases and (iii) persons with no history of Leishmania infection. The supernatants of stimulated PBMCs were analysed for production of IL-10, IFN-gamma and IL-2. Robust production of IL-10 in response to Leishmania stimulation was observed in active ACL cases, compared to low levels in asymptomatic cases and negative controls. Serum IgE levels, measured by ELISA, were not significantly different among the three groups. In addition, ACL cases displayed depressed levels of all cytokines in response to mitogen. Thus, this first characterization of the immune response in ACL suggests a role for IL-10 as well as partial immunosuppression.

[Detection of antibodies against Trypanosoma cruzi in Somoto, Nicaragua, using indirect ELISA and IFI on blood samples on filter paper]. / Detección de anticuerpos contra Trypanosoma cruzi en Somoto, Nicaragua, mediante ELISA indirecto e IFI en muestras de sangre en papel de filtro.

We standardized a solid-phase enzyme-linked immunosorbent assay (ELISA) in order to study the presence of Trypanosoma cruzi antibodies in asymptomatic persons who live in an area of Nicaragua endemic for Chagas' disease. The test was standardized to analyze filter-paper blood samples, which are easy to transport. In the first phase of our investigation, ELISA was used to study 18 samples of total serum and 18 eluates of blood from patients with chronic Chagas' disease; 30 samples of serum and 30 eluates of blood from healthy people, used as negative controls; and 14 samples of serum and 14 eluates of blood from patients with cutaneous or visceral leishmaniasis, which were used to study cross-reactions. Both with the total-serum and the blood-eluate samples, the ELISA test provided 100% sensitivity and 90% specificity. Cross-reactions in the patient samples were observed only with visceral leishmaniasis. The second phase of our investigation was a population study that included eight rural communities in the area of Somoto, Nicaragua. Through random sampling, filter-paper blood samples were collected from 2,434 people (1,335 men and 1,099 women) from the communities of Aguas Calientes, El Brocal, La Manzana, Las Playas, Los Canales, Santa Isabel, Santa Rosa, and Santa Teresa. Studied by ELISA and by indirect immunofluorescence (IIF), the samples included 260 found seropositive by ELISA (10.7%), of which 207 were positive according to IIF (8.5%). With both techniques, the majority of seropositives were among women, but the difference between men and women was not statistically significant. There was a high level of agreement between the results obtained with the two techniques. There was an upward trend with age, with 5.4% of those found seropositive by ELISA being persons 10 years of age or younger and 42.7% of those found seropositive being older than 50. The vast majority of the individuals analyzed were asymptomatic.

Widespread atypical cutaneous Leishmaniasis caused by Leishmania (L.) Chagasi in Nicaragua.

Leishmania chagasi, the causative agent of visceral leishmaniasis (VL) in the Americas, has recently been associated with atypical cutaneous leishmaniasis (ACL) in Central America; however, little comprehensive information about this disease is available. Clinical, epidemiologic, and parasitologic characteristics of 252 ACL cases and 44 VL cases in Nicaragua were analyzed. Visceral leishmaniasis is primarily associated with malnourished children less than five years of age, whereas ACL is found predominantly in children greater than five years of age and young adults. Genetically similar parasites are associated with both disease manifestations. The sand fly Lutzomyia evansi, in addition to Lu. longipalpis, may be involved in transmission of L. chagasi to humans. Our results indicate that ACL is more prevalent than previously thought, affecting up to 10% of a local population. The fact that the same parasite appears to cause both ACL and the potentially fatal visceral disease suggests that the host immune response is critical in determining the outcome of L. chagasi infection. The public health implications of the wide-spread presence of L. chagasi are discussed.