Detección de anticuerpos contra Trypanosoma cruzi en Somoto, Nicaragua, mediante ELISA indirecto e IFI en muestras de sangre en papel de filtro

Abstract

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.

Prevalence of Chagas Disease in Latin-American Migrants Living in Europe: A Systematic Review and Meta-analysis

“…However, it is noteworthy that these data differ significantly from PAHO estimates, in the case of Nicaragua representing a four-fold increase. Although data on the prevalence of Chagas disease in Central America is scarce, a prevalence as high as 8,5% was found in a sample taken from patients in the area of Somoto in Nicaragua[ 41 ]. The heterogeneity and smaller size of migrant communities analysed in some studies, especially in the case of countries from Central America, with relatively little representation in European countries, represents a challenge to achieve statistically relevant information.…”

Urban Chagas disease in children and women in primary care centres in Buenos Aires, Argentina

“…Validation of the dry blood spot serological method ( Zicker et al 1990 , Palacios et al. 2000 ) - Blood samples for serological screening were obtained on filter paper (Schleicher & Schuell ® no.…”

“…Fifty-six samples were from patients with T. cruzi infection confirmed via conventional serology testing and 19 samples were from noninfected patients. Based on the validation results and from previously published data on the method ( Zicker et al 1990 , Palacios et al 2000) , the following cut off values were chosen for screening with the filter paper method: IHA ≥ 1/8 dilutions, ELISA R ≥ 0.8 (R = optic density of the simple/optic density of the negative control).…”

The use of an excreted superoxide dismutase in an ELISA and Western blotting for the diagnosis of Leishmania (Leishmania) infantum naturally infected dogs

“…A possible solution for eliminating the cross-reactions is to purify the soluble extract to obtain specific antigens from Leishmania species (Palacios et al 2000). In this sense, some authors have pointed out that the cross-reactions are reduced between Leishmania spp.…”

“…In this sense, some authors have pointed out that the cross-reactions are reduced between Leishmania spp. and T. cruzi when using certain immunogenic proteins such as GP57/51 (Boldano et al 1991) or the glycoprotein of 90 kDa (GP90), which are found in the zymodemes of T. cruzi but which are absent in those of Leishmania and T. rangeli (Palacios et al 2000). The SODe of L. (L.) infantum appears to be another immunogenic protein specific for detecting sera of ailing dogs.…”