Assessment of the rapid test based on an immunochromatography technique for detecting anti-Treponema pallidum antibodies

A rapid test based on an immunochromatography assay - Determine™ Syphilis TP (Abbott Lab.) for detecting specific antibodies to Treponema pallidum was evaluated against serum samples from patients with clinical, epidemiological and serological diagnosis of syphilis, patients with sexually transmitted disease other than syphilis, and individuals with negative serology for syphilis. The Determine™ test presented the sensitivity of 93.6%, specificity of 92.5%, and positive predictive value and negative predictive value of 95.2% and 93.7%, respectively. One serum sample from patient with recent latent syphilis showed a prozone reaction. Determine™ is a rapid assay, highly specific and easy to perform. This technique obviates the need of equipment and its diagnostic features demonstrate that it may be applicable as an alternative assay for syphilis screening under some emergency conditions or for patients living in remote localities.

Human toxocariasis: frequency of anti-Toxocara antibodies in children and adolescents from an outpatient clinic for lymphatic filariasis in Recife, Northeast Brazil

In a transversal study on a sample of 386 children and adolescents from an outpatient clinic for filariasis in Recife, Northeast Brazil, the frequency of anti-Toxocara antibodies and its relation to age, gender, number of peripheral eosinophils, Wuchereria bancrofti microfilariae and intestinal helminths was determined. The total anti-Toxocara IgG antibody frequency was 39.4%, by ELISA technique. The difference in frequency between males (40.1%) and females (37.6%) was not statistically significant. The 6 to 10-year-old subset presented the highest frequency of anti-Toxocara antibodies (60%), and within this age group there was a statistically significant male bias. There was also a significant association between the number of eosinophils and the presence of anti-Toxocara antibodies. Intestinal parasite frequency was 52.1%, but no association was found between this data and the presence of anti-Toxocara antibodies. In the present sample, 42.2% of the patients were Wuchereria bancrofti carriers, however, again this was not associated with the presence of anti-Toxocara antibodies. In conclusion, anti-Toxocara antibodies were highly prevalent in this sample. The present data show that there is no cross correlation between anti-Toxocara IgG antibody and the presence of intestinal helminths and filariasis.

Prevalence of IgG varicella zoster virus antibodies in the Kuikuro and Kaiabi indigenous communities in Xingu National Park, Brazil, before varicella vaccination

The purpose of the study was to estimate the prevalence of IgG antibodies against varicella zoster virus (VZV) in the two most populated indigenous ethnic groups from Xingu Indigenous National Park, in Brazil, prior to the introduction of vaccination against the disease, and to determine the positive and the negative predictive values of a history of varicella infection. In 2001, 589 inhabitants of two Kuikuro villages and three Kaiabi villages were evaluated and provided information concerning previous varicella infection. An indirect immunosorbent assay (ELISA) to detect IgG anti-VZV antibodies was performed in 224 blood samples - volunteer selection had no interference of anamnesis. IgG prevalence was 80.8% (95% Confidence Interval: 76% - 86%). The seroepidemiology of varicella in Xingu National Park prior to varicella vaccine introduction was comparable to the Brazilian national seroprevalence described in the literature, and so were the positive (98%) and the negative predictive value (41%) of the referred history.

Cysticercus antibodies and antigens in serum from blood donors from Pondicherry, India

The aim of the present study was to screen the serum of blood donors, which are apparently healthy and residing in Pondicherry or its neighboring districts of Tamil Nadu State, for specific detection of Cysticercus antigens and antibodies. A total of 216 blood samples were collected from blood donors at the Central Blood Bank, JIPMER Hospital, Pondicherry, India during January and February 2004. Enzyme-linked immunosorbent assay (ELISA) was used to demonstrate anti-Cysticercus antibodies and the Co-agglutination (CoA) was used to detect antigen in sera. 14 (6.48 %) males were positive for either anti-Cysticercus antibodies or antigens. Of these eight sera were positive for anti-Cysticercus antibodies and six were positive for antigens. Results of the present study show that serum Cysticercus antigen detection may be a useful adjunct to antibody testing for seroprevalence studies of cysticercosis in the community. The present study is the first kind of study, carried out to determine both cysticercal antibodies as well as antigens in the serum samples collected from the healthy blood donors.

Anti-Taenia solium metacestode IgG antibodies in serum samples from inhabitants of a central-western region of Brazil

A total of 354 serum samples from inhabitants who frequent the Clinical Laboratory in Catalão, Goiás, in the central-western region of Brazil, were collected from June to August, 2002. The samples were evaluated by indirect immunofluorescence antibody tests and an enzyme linked immunosorbent assay in order to detect anti-Taenia solium metacestode IgG antibodies. Reactive and inconclusive samples were tested by Western blotting (WB). Considering WB as a confirmation, the frequency of antibodies in the serum samples of the above population was 11.3% (CI 5.09 - 17.51). The immunodominant bands most frequently recognized in WB were 64-68 kDa (97.5%) and 47-52 kDa (80%). The percentage of seropositivity to cysticercosis was significantly higher for individuals residing in areas without sewage systems (p < 0.0001). In conclusion, the results indicate a probable endemic situation of cysticercosis in this population. These results reinforce the urgent need for control and prevention measures to be taken by the local public health services.

Thermostability of heterophile antibodies from human sera infected with Schistosoma mansoni and geo-helminths: an immuno-metric statistical analysis

Antibody in human sera that induces lysis of sheep erythrocytes in hemolytic assay was investigated. The present study showed that the presence in serum of the thermostable cytolytic anti-sheep red blood cells antibodies is dependent on the Schistosoma mansoni infection, and this is more frequent in adults than in children. The thermostable characteristic of hemolysins in normal sera was not dependent on the presence of Ascaris lumbricoides, Trichuris trichiura or hookworm geo-helminths. Further, thermostable complement-activating heterophile antibodies were noticed in children in association with massive number of S. mansoni eggs. The results were obtained by using the z- and the chi-square tests. The z-test allows us to formulate a one-sided alternative, i.e., a tendency of one of the attributes. On the other hand, the chi-square test analyzes the independence between attributes by using a contingency table. Besides the obtained results being interesting in the field of schistosomiasis mansoni, they can provide a new insight into the use of statistics in medical science.

Sensitivity of an immunoenzymatic test for detection of ant-L. brasiliensis antibodies compared to other tests used for the diagnosis of American cutaneous leishmaniasis

The diagnosis of American cutaneous leishmaniasis (ACL) is frequently based on clinical and epidemiological data associated with the results of laboratory tests. Some laboratory methods are currently being applied for the diagnosis of ACL, among them the indirect immunofluorescence reaction (IIFR), the Montenegro skin test (MST), histopathological examination, and the polymerase chain reaction (PCR). The performance of these methods varies in a considerable proportion of patients. After the standardization of an immunoenzymatic test (ELISA) for the detection of IgG in the serum of patients with ACL using a crude Leishmania braziliensis antigen, the results obtained were compared to those of other tests routinely used for the diagnosis. The tests revealed the following sensitivity, when analyzed separately: 85% for ELISA IgG, 81% for PCR, 64.4% for MST, 58.1% for IIFR, and 34% for the presence of parasites in the biopsy. ELISA was positive in 75% of patients with ACL presenting a negative MST, in 84.8% of ACL patients with negative skin or mucous biopsies for the presence of the parasite, and in 100% of cases with a negative PCR. Thus, ELISA presented a higher sensitivity than the other tests and was useful as a complementary method for the diagnosis of ACL.

Prevalence of antibodies against hepatitis A virus among the Kuikuro and Kaiabi Indians of Xingu National Park, Brazil

A seroprevalence study to detect total antibodies against Hepatitis A Virus was done with 220 samples from 589 Native Indians from Xingu National Park, Brazil, in five Kaiabi and Kuikuro villages, the most populous ethnic groups. Using a commercial immunoassay kit we detected 97.7% positive samples (95% Confidence Interval: 95%-99%). We noticed a precocious seroconversion, before the age of six years, when the disease is usually asymptomatic. These results are similar to those found in the literature in non-Indian population studies of the Northern, Northeastern and West Central regions of Brazil. They suggest that it is not necessary to introduce vaccination against Hepatitis A in these highly endemic populations.

Characterization of a clone from an adult worm cDNA library selected with anti-Schistosoma mansoni human antibodies dissociated from immune complexes: a preliminary report

Considering the scarcity of defined antigens, actually useful and reliable for use in the field studies, we propose an alternative method for selection of cDNA clones with potential use in the diagnosis of schistosomiasis. Human antibodies specific to a protein fraction of 31/32 kDa (Sm31/32), dissociated from immune complexes, are used for screening of clones from an adult worm cDNA library. Partial sequencing of five clones, selected through this strategy, showed to be related to Schistosoma mansoni: two were identified as homologous to heat shock protein 70, one to glutathione S-transferase, one to homeodomain protein, and one to a previously described EST (expressed sequence tag) of S. mansoni. This last clone was the most consistently reactive during the screening process with the anti-Sm31/32 antibodies dissociated from the immune complexes. The complete sequence of this clone was obtained and the translation data yielded only one ORF (open reading frame) that code for a protein with 57 amino acids. Based on this amino acid sequence two peptides were chemically synthesized and evaluated separately against a pool of serum samples from schistosomiasis patients and non-schistosomiasis individuals. Both peptides showed strong reactivity only against the positive pool, suggesting that these peptides may be useful as antigens for the diagnosis of schistosomiasis mansoni.

Occurrence of antibodies against Leptospira spp. in horses of the urban area of Londrina, Paraná, Brazil

A total of 320 horses were studied in this paper, both male and female, between two and 17 years of age, which were used for traction of wagons in the urban area of the municipality of Londrina (PR). These animals were kept, after their daily work, in abandoned areas or plots, in the outskirts of the urban area of the city. When these animals were attended by the veterinarians, between 1996 and 2005, none of them presented symptoms suggesting leptospirosis. The most frequent reasons for the visit were loss of weight, unwillingness for work, parasitism, laminess, and wounds. Microscopic Seroagglutination Test (SAM), with 22 Leptospira serovars, was performed in sera sample from all these animals. The aim of this study was to investigate the occurrence of antibodies against Leptospira spp. in horses from the urban area of Londrina (PR). From the samples tested, 214 (66.88%) were considered positive, with titers between 100 and 3200, being that 49 (22.90%) presented antibodies against a single serovar of Leptospira, and 165 (77.10%) samples presented antibodies against two or more serovars simultaneously, where in 88 (53.33%) it was possible to characterize the most likely probable serovar. Antibodies against the serovar Icterohaemorrhagiae were detected in 32 (23.36%) animals.

Detection of Cysticercus antigens and antibodies in cerbrospinal fluid of patients with chronic meningitis

Chronic meningitism is a less frequent manifestation of neurocysticercosis caused by Taenia solium cysticerci. In the present study we used Co-agglutination (Co-A), a simple and rapid slide agglutination test to detect specific Cysticercus antigen in the 67 cerebrospinal fluid (CSF) samples from patients with chronic meningitis of unknown etiology. The results were compared with that of ELISA for detection of antibodies. Among these samples four (5.97%) were positive for Cysticercus antigen by Co-A test and six (8.95%) were positive for antibodies by ELISA. Two samples were positive by both Co-A and ELISA, two were positive only by Co-A and four were positive only by ELISA. In the present study, although Cysticercus antigen and antibodies were present in CSF samples from eight (11.94%) patients, we cannot affirm that all the cases of chronic meningitis are due to cysticercosis, but for any case of chronic meningitis of unknown origin, it would be useful to consider the possibility of cysticercal meningitis.

Evaluation of the human immunodeficiency virus type 1 and 2 antibodies detection in dried whole blood spots (dbs) samples

Human Immunodeficiency Vírus Type 1 and 2 antibodies detection was performed in 457 dried whole blood spots samples (S&S 903). Q-Preven HIV 1+2 was the screening test used. The results were compared with the gold standard serum tests by ELISA (Cobas Core e Axsym HIV1/2 gO) and imunofluorescence was the definitive confirmatory test. The samples were obtained from the Hospital Nossa Senhora da Conceição in Porto Alegre, RS - Brazil, through whole blood transfer to filter paper card and sent to Caxias do Sul, RS - Brazil where the tests were performed. The dried whole blood spot stability was evaluated with two different panels. The first one was composed of five negative and five positive samples stored at room temperature, 4 ºC, -20 ºC and -70 ºC, while the second was composed of two negative and three positive samples stored at 37 ºC (humidity <50%). Each sample was screened every week for six weeks. These measurement results didn't show variation during the study period. The detected sensibility was 100%, specificity was 99.6%, the positive predictive value was 99.5% and negative predictive values were 100%. The results demonstrated high performance characteristics, opening a new perspective of dried whole blood spot utilization in HIV screening diagnosis.

Circulation of antibodies against yellow fever virus in a simian population in the area of Porto Primavera Hydroelectric Plant, São Paulo, Brazil

Yellow fever (YF) is an acute viral infectious disease transmitted by mosquitoes which occurs in two distinct epidemiological cycles: sylvatic and urban. In the sylvatic cycle, the virus is maintained by monkey's infection and transovarian transmission in vectors. Surveillance of non-human primates is required for the detection of viral circulation during epizootics, and for the identification of unaffected or transition areas. An ELISA (enzyme-linked immunosorbent assay) was standardized for estimation of the prevalence of IgG antibodies against yellow fever virus in monkey sera (Alouatta caraya) from the reservoir area of Porto Primavera Hydroelectric Plant, in the state of São Paulo, Brazil. A total of 570 monkey sera samples were tested and none was reactive to antibodies against yellow fever virus. The results corroborate the epidemiology of yellow fever in the area. Even though it is considered a transition area, there were no reports to date of epizootics or yellow fever outbreaks in humans. Also, entomological investigations did not detect the presence of vectors of this arbovirus infection. ELISA proved to be fast, sensitive, an adequate assay, and an instrument for active search in the epidemiological surveillance of yellow fever allowing the implementation of prevention actions, even before the occurrence of epizootics.