Rosemere Duarte

Phase 1 Study of an Inactivated Vaccine against American Tegumentary Leishmaniasis in Normal Volunteers in Brazil

A Phase 1 double-blind placebo-controlled study was performed to evaluate a vaccine against American tegumentary leishmaniasis in 61 healthy male volunteers. Side effects and the immune response to the vaccine were evaluated, with 1- and 2- dose schemes, with intervals of 7 or 21 days, each dose containing 1440 mg of protein N antigen of a single strain of Leishmania amazonensis (PH8) diluted in merthiolated saline (1:10,000). Merthiolated saline and an inert substance were used as placebos. No significant clinical alterations were found following the respective injections in the vaccinated individuals as compared to the placebos, except for local pain, which was associated significantly with injection of the vaccine. The laboratory alterations we observed bore no association with the clinical findings and were unimportant. We observed no differences between the groups with regard to seroconversion of the Montenegro skin test. However, the group that received a single dose of the vaccine and the one that received two doses with a 21-day interval displayed cutaneous induration significantly larger than in the control group, with 100%, 100%, and 66% conversion in the skin test, respectively. We concluded that the vaccine does not present any major side effect that would contraindicate its use in healthy individuals.

Detection of Giardia duodenalis antigen in coprolites using a commercially available enzyme-linked immunosorbent assay

The objective of this experiment was to assess the utility of a commercially available enzyme-linked immunosorbent assay (ELISA) kit for diagnosis of giardiasis in archaeological human remains. The kit, a monoclonal antibody assay, is used to detect the presence of Giardia-specific antigen 65 (GSA65) in human faeces. We utilized the assay in ancient faecal material. The material included desiccated faeces found in mummies or in archaeological sites, and sediments from latrines. A total of 83 specimens, previously examined microscopically for parasites, were examined. The ELISA detected 3 positive samples, dated to about 1200 AD, 1600 AD and 1700 AD. The ELISA was superior to direct observation. It was possible to identify G. duodenalis cysts by direct microscopy in only one of these samples. The results did not show cross-reactivity between this protozoan and helminths. The use of ELISA to detect G. duodenalis coproantigen could help the diagnosis of giardiasis in ancient human remains.

Leishmania (Viannia) braziliensis em cães naturalmente infectados

Eight dogs from Marica Municipality (RJ), with suggestive lesion of american tegumentary leishmaniasis were studied by parasitological and serological methods. Leishmania spp was found in six dogs by in vitro cultivation. Specific antibodies were detected in six dogs by ELISA and in two by indirect immunofluorescence. Five canine isolates were found to belong to the same zymodeme as Leishmania (Viannia) braziliensis. The authors suggest that clinically suspect dogs should be followed-up in an attempt to confirm the diagnostic of canine tegumentary leishmaniasis.

Feeding sources and natural infection of Belminus herreri (Hemiptera, Reduviidae, Triatominae) from dwellings in Cesar, Colombia

Belminus herreri, originally described from specimens collected in Panama, was considered entirely silvatic until to 2000 when it was found for the first time in a domestic habitat in Colombia. In 2001, during a new search of houses in the Department of Cesar, Colombia, 121 specimens were collected. Study of their feeding sources using an ELISA test revealed that 96% of these specimens had fed on cockroaches (Blattidae). However, a small proportion of these B. herreri specimens also showed the presence of Trypanosoma cruzi in their gut contents, suggesting a possible role for these insects in the epidemiology of Chagas disease.

Standardization of enzyme-linked immunosorbent assay ELISA to detect anti-Toxoplasma gondii IgM and IgG antibodies, and comparison with the indirect immunofluorescence technique

Serology has been the most popular method to diagnose toxoplasmosis. Accordingly, this study standardizes an enzyme-linked immunosorbent assay (ELISA) and compares its results with the IFI technique. In the IgG detection test, the standardized technique presented a sensibility (S) of 96.77%, a specificity (SP) of 75%, with a positive predictive value (PPV) of 83.33%, a negative predictive value (NPV) of 94.74%, and an adjusted concordance (K) of 73.50%. The IFI exhibited 83.87% for S, 79.16% for SP, 83.81% for PPV, 79. 16% for NPV, and 63% for K. The rough concordance between these two tests (ELISA/IFI) was 88.35% for the IgG detection test and 81.55% for the IgM detection test. K was 70.82% and 1.31% for IgG and IgM, respectively, the correlation index (r) being 0.556 for IgG and -0. 023 for IgM. We can conclude that standardized ELISA-IgG is indicated in serologic selection processes, whereas the ELISA-IgM is not recommended for presenting low values for the adjusted concordance with the reference technique, which suggests not very reliable results.

Studies on the Feeding Habits of Lutzomyia (Lutzomyia) longipalpis (Lutz & Neiva, 1912) (Diptera: Psychodidae: Phlebotominae) Populations from Endemic Areas of American Visceral Leishmaniasis in Northeastern Brazil

The aim of this study was to identify potential blood feeding sources of L. (L.) longipalpis specimens from populations in Northeastern Brazil, endemic areas of American Visceral Leishmaniasis (AVL) and its correlation with the transmission of L. (L.) i. chagasi. The ELISA technique was applied using bird, dog, goat, opossum, equine, feline, human, sheep, and rodent antisera to analyze 609 females, resulting in an overall positivity of 60%. In all municipalities, females showed higher positivity for bird followed by dog antiserum and sand fly specimens were also positive for equine, feline, human, sheep, goat, opossum, and rodent antisera. The finding for 17 combinations of two or three types of blood in some females corroborates the opportunistic habit of this sand fly species. The results demonstrating the association between L. (L.) longipalpis and opossum suggest the need for further evaluation of the real role of this synanthropic mammal in the eco-epidemiology of AVL.

Genetic polymorphism in Trypanosoma cruzi I isolated from Brazilian Northeast triatomines revealed by low-stringency single specific primer–polymerase chain reaction

Different molecular markers have been employed for typing Trypanosoma cruzi strains from endemic areas of Chagas disease. The low-stringency single specific primer–polymerase chain reaction (LSSP–PCR) has been a sensitive and informative technique that uses the variable region of kinetoplast DNA minicircles as a genetic marker, allowing detection of DNA sequence variation. In the present study, we analyzed the intra-lineage genetic variability of the T. cruzi strains obtained from triatomine feces collected on filter paper FTA card by LSSP–PCR. The hybridization of the PCR products with a probe for the subgenus Schizotrypanum and a clone-specific probe from Dm28c confirmed the subgenus as T. (S.) cruzi and respective lineages as T. cruzi I. Phenetic analysis showed the presence of three clusters that diverged by different coefficients of similarity. Thirteen T. cruzi I genotypes were observed circulating among Triatoma pseudomaculata and Rhodnius nasutus from peridomiciliary and natural environments in five peri-urban and urban localities of Jaguaruana, Ceará, Brazil. These data indicate the importance of the circulation of T. cruzi I genotypes among T. pseudomaculata and R. nasutus in different environments and the possible risk of Chagas disease domestic transmission.

Aspectos sorológicos e epidemiológicos da leishmaniose tegumentar americana canina em Maricá, Rio de Janeiro, Brasil

A sample of 261 dogs from 134 households located in a periurban area of Maricá, Rio de Janeiro, Brazil, was studied to evaluate serologic reactions and active infection of american tegumentary leishmaniasis (ATL). Eight dogs presented lesions suggestive of ATL, but this was isolated in only three. Using ELISA, 24.5% (64/261) of the dogs studied were positive (sensitivity = 66% and specificity = 76%), associated with isolation in 2 animals and 0.4% (1/261) by indirect immunofluorescence assay (IIF) with no association with isolation. In order to reduce the unspecific reactions to ELISA, a second criterion was used to obtain the cutoff (sensitivity = 33% and specificity = 93%), resulting in a reactivity of 6.9 % (18/261) associated to isolation in a single animal. As observed in this study, serologic results by IIF were not associated with active infection and ELISA showed high unspecific reactions, indicating that the serologic reactions alone are not recommended for ATL diagnosis. ATL scars were been observed in 7 persons in the region and active lesion, under treatment, was observed in one patient. The finding of active lesions, either in dogs or humans, confirmed the existence of active tegumentary leishmaniasis in Maricá, indicating the need for further studies to evaluate the importance of this infection in the municipality.

Ecology of Triatoma brasiliensis in Northeastern Brazil: Seasonal Distribution, Feeding Resources, and Trypanosoma cruzi Infection in a Sylvatic Population

ABSTRACT: We assessed some ecological parameters of Triatoma brasiliensis in rock piles in the state of Ceará during the rainy and dry seasons. The greatest density was in April (median = 12.5 triatomines/site). The greatest abundance was in December, when the insects were more dispersed and the density per site was lower (6 triatomines/site). The nutritional status of females and 5th instar nymphs was increased in July. The rate of T. cruzi infection reached its highest peak in July (10.9%). ELISA revealed that the principal food sources were birds (33.1%), followed by armadillos (18.8%). Food sources were more frequently identified during the rainy season. T. brasiliensis specimens collected in the drought tended to: i) present lower rates of T. cruzi infection and gut content reactivity to tested antisera, ii) have a poorer nutritional status, iii) exhibit lower fecundity, iv) be more dispersed among the studied collection sites, and v) be more abundant and easily collected in the surface of the rocks, possibly reflecting an increased searching for blood meals. Such findings underscore epidemiological concerns and allow inferences about the season when triatomines can more frequently invade the peridomestic environment in search of food and recolonize artificial structures.

Triatoma rubrovaria (Blanchard, 1843) (Hemiptera, Reduviidae, Triatominae) II: trophic resources and ecological observations of five populations collected in the State of Rio Grande do Sul, Brazil

Triatoma rubrovaria has become the most frequently captured triatomine species after the control of T. infestans in the State of Rio Grande do Sul (RS), Brazil. Isoenzymatic and chromatic studies indicate the existence of, at least, two distinct phenotypic patterns of T. rubrovaria in RS. The geographic variation noted through molecular tools may also result in distinct profiles of vectorial potentiality. In order to enhance our understanding of the bionomic knowledge of T. rubrovaria separate batches of the species were collected from different municipalities of RS distant from 72 to 332 km: Santana do Livramento (natural ecotope), Santana do Livramento (artificial ecotope), Santiago (natural ecotope), Cangu u (peridomicile) and Encruzilhada do Sul (natural ecotope). A total of 285 specimens were collected, 85 specimens kept sufficient fecal material in their guts for the precipitin analysis. The results indicated the food eclecticism for this species and the anti-rodent serum showed the highest positivity in most localities. From the total of analyzed samples, only 1.3% of unique positivity for human blood was registered, all of them for Santiago population. This reactivity to human blood may be associated to pastures activities in the field.