Blood parasites of some birds from São Paulo State, Brazil

A total of 3.449 birds, representing 195 species of 33 families from three areas in São Paulo State, Brazil, were examined for hematozoa during the period 1967-1972. Only 268 birds (7.8%) of 21 families harbored a blood parasite, which represented by species of Haemoproteus (3.5%), microfilaria (2.6%), Plasmodium (1.8%), Trypanosoma (0.8%) and Leucocytozoon (0.06%). The prevalence was similar in each of the six years of the study but a marked decrease in prevalence was noted in February and June of each year. The prevalence of parasitism was significantly different in each of the three areas sampled.

Saccocoelioides godoyi n.sp. (Haploporidae) and other trematodes parasites of fishes from the Guaiba estuary, RS, Brazil

One hundred and fourteen specimens of eleven different species of freshwater fishes from the Guaiba estuary, were examined for digenetic flukes. Saccocoelioides godoyi n.sp. proposed herein, is closest to S. magniovatus and to S. szidati; S. magniovatus is much smaller with comparably larger eggs and S. szidati has larger hermaphroditic sac and considerably larger testis. Creptotrema creptotrema is referred to a new host; Acanthostomum gnerii, Crepidostomum platense, Eocreadium intermedium (immature form), Parspina argentinensis and Zonocotyle bicaecata are reported. This paper confirms the similatary between the parasites of freshwater fishes from Argentina and Brazil. Measurements and original figures of all species are given.

La queratotaxia cercariana en la diferenciacion de sexos de schistosoma mansoni

El número de papilas argirófilas superficiales y su modelo de disposición en el tegumento de las cercarias (quetotaxia) de Schistosoma mansoni nos permitió diferenciar los sexos a nivel del mencionado estadío larvario, mediante los siguientes critérios: - Mayor homogeneidad en las cercarias machos, en cuanto al número total de papilas ventrales y dorsales a nivel de cuerpo y cola cercarianos (C.V. = 4,1%), que en las cercarias hembras (C. V. = 18,3%) (P < 0,001). - Presencia en el 80% de las cercarias machos de cuatro papilas en los cuadrantes "C" ó "D" )inferior-izquierdo e inferior-derecho, respectivamente) ventrales, mientras que dicho caracter sólo está presente en el 40% de las cercarias hembras (P < 0,001). - Diferencia estadísticamente significativa (P < 0,001) entre el número total promedio de papilas corporales centrales de las cercarias hembras (X = 11,9 ± 0,2) y el de las cercarias machos (X = 11,1 ± 0,3). - Diferencia estadísticamente significativa (P < 0,05) para la mayor distancia promedio entre las papilas AIL y AIIL, de cada cercaria, en relación con el sexo (femenino = 25,5 µm ± 0,33; masculino = 27,3 µm ± 0,26).

Toxoplasma gondii: a rapid method for the isolation of pure tachyzoites: preliminary characterization of its genome

A rapid and simple technique for the purification of Toxoplasma gondii tachyzoites was developed. Highly purified parasites were obtained from the peritoneal exudates of infected mice by means of two consecutive discontinous sucrose gradients run at low speed (10,000xg, 30 min). Parasites obtained by this method conserved its biological activity. Hybridizations tudies with DNA from healthy mice and from purified tachyzoites preparations demonstrated that Toxoplasma gondii tachyzoites DNA could be obtained with better than 90 per cents purity. Preliminary studies with DNA endonucleases showed the presence in the tachyzoites genome of highly repetitives sequences.

Molecular analysis of yellow fever virus 17DD vaccine strain

The Oswaldo Cruz Foundation produces most of the yellow fever (YF) vaccine prepared world wide. As part of a broader approach to determine the genetic variability in YF l7D seeds and vaccines and its relevance to viral attenuation the 17DD virus was purifed directly from chick embryo homogenates which is the source of virus used for vaccination of millions of people in Brazil and other countries for half a century. Neutralization and hemagglutination tests showed that the purified virus is similar to the original stock. Furthermore, radioimmune precipitation of 35S-methionine-labeled viral proteins using mouse hyperimmune ascitic fluid revealed identical patterns for the purified 17DD virus and the YF l7D-204 strain except for the 17DD E protein which migrated slower on SDS-PAGE. This difference is likely to be due to N-linked glycosylation. Finally, comparison by northern blot nybridization of virion RNAs of purified 17DD with two other strains of YF virus only fenome-sized molecules for all three viruses. These observations suggest that vaccine phenotype is primarily associated with the accumulation of mutations.

New approaches for the control and eradication of schistosomiasis in Venezuela

Schistosomiasis in Americawith the exception of Brazil, behaves as a chronic mild disease with few clinical manifestations due to low parasite burden. These features restrict the clinical and parasitological diagnosis. The most commonly used stool examination method, Kato-Katz, becomes intensitive when the majority of individuals excrete less than 100 eggs/g of feces. In view that antigen-detecting techniques have not been able to reveal light infections, the antibody detecting assays remain as a very valuable diagnostic tool for epidemiological surveillance. The Venezuelan Schistosomiasis Research group (CECOICE) has designed a mass chemotherapy strategy based on sero-diagnosis. Since blood sampling is one of the important limitating factors for large seroepidemiological trials we developed a simple capillary technique that sucessfully overcomed most of the limitations of blood drawing. In this sense, ELISA seems to be the most adecuate test for epidemiological studies. Soluble egg Schistosoma mansoni antigen (SEA) has been largely used in Venezuela. The sensitivity ELISA-SEA in our hands is 90% moreover its specific reach 92% when populations from non-endemic areas but heavily infected with other intestinal parasites are analyzed. The Schistosomiasis Control Program is currently carrying out the surveillance of endemic areas using ELISA-SEA as the first screening method, followed by the Circumoval Precipitin test for validation assay. The results with these two serological techniques allowed us to defined the criteria of chemotherapy in populations of the endemic areas. On the search of better diagnostic technique, Alkaline Phosphatase Immunoenzyme Assay (APIA) is being evaluated in field surveys.

Electrocardiographic alteration among first degree relatives with serologic evidence of Trypanosoma cruzi infection: a sibship study

To analyze whether electrocardiographic alterations (ECGA) in patients with antibodies to Trypanosoma cruzi showed a patttern of familial aggregation, a sample of 379 young adults (166 men and 213 women) distributed in sibships, were assessed for the presence of anti-T.cruzi antibodies, and subjected to a complete clinical examination and a standard resting electrocardiogram (ECG). Positive T. cruzi serology was detected in 165 individuals, 48 of them showing an abnormal ECG (overall prevalence 29 por cento). One hundred and eleven seropositive individuals were distributed in 45 sibships, each of them constituted by more than one seropositive sib, with ECGA being present in 34 out of these patients. Seropositive subjects with ECGA were detected in 27 sibships. Since the index case within each sibship is counted exactly once, affected individuals selected at random as propositi were extracted to calculate the prevalence of ECGA among first degree relatives of probands. Abnormal ECGs were recorded in 7 out of 45 sibs yielding a prevalence that did not differ from estimations registered in the general population or seropositive sibs. Data from the present sample show no familial aggregation for the occurrence of ECGA in patients with T.cruzi infection.

Low occurrence of arthritic manifestations in patients with pulmonary tuberculosis: T cell subsets and humoral studies

Given the suspected role of mycobacteria in the establishment of disorders with an autoimmune background and joint damage, a study was conducted to analize whether rheumatic symptoms were likely to be present in tuberculosis (TB) patients. To this end, 330 patients with a bacteriologic confirmation of tuberculosis were investigated for the presence of arthritic complaints. The latter were recorded in five of them with rheumatic symptoms mostly involving interphalangeal and metacarpophalanged joints, and preceding the clinical manifestations of the TB illness. Three out of these five patients remained arthritic by the time of the bacteriologic conversion and fulfilled the criteria for the diagnosis of rheumatoid arthritis. In the two remaining patients sputum negativization was accompanied by a disappearance of rheumatic manifestations. These patients were also assessed for their peripheral levels of major T cell subsets as well as for the presence of autoantibodies. Comparisons with a series of non-arthritic TB cases, rheumatoid arthritis patients, and controls revealed that presence of rheumatic manifestations was associated with a different profile of autoantibody formation and T cell subset changes. Evidence recorded in the present study indicates that joint affectation in TB is a rare event, being rather the exception than the rule.

The immunopathology of human schistosomiasis-III: immunoglobulin isotype profiles and response to praziquantel

Immunoglobulin (Ig) isotype (IgG, IgG1, IgG2, IgG3, IgG4, IgM, IgD and IgE) levels were investigated, both pre- and post-treatment with praziquantel (PZQ), in 43 adults and children chronically infected with Schistosoma mansoni , by means of a two-site, isotype-specific immunoenzymometric assay. The patients were classified as responders (R) or non-responders (NR) on the basis of their circumoval precipitin test (COPT) results 12 months after treatment. In comparison with controls, pre-treatment R children showed significantly higher levels of IgG, IgG1, IgG4 (p<0.001) and IgE (p<0.01), and diminished IgG2 (p<0.05), while NR children showed significantly elevated levels only of IgE (p<0.05). Twelve months after therapy, R children maintained significantly lower levels of IgG2, but showed significantly decreased levels of IgG, IgG1, IgG4, and IgE, while the Ig isotype profile of NR children was unaltered. Adult R and NR showed similar isotype profiles before chemotherapy, with the exception of significantly elevated IgM levels in R. Twelve months after therapy, R adults showed significantly decreased levels of IgG, IgG1, and IgG4, while NR adults showed only diminshed IgG4 levels. These results reveal different Ig isotype profiles in untreated adults and children chronically infected with S. mansoni. The results further show that the pre-treatment Ig isotype profile may be significantly modified after an effective R to chemotherapy, accounted for by down regulation of the IgG1 isotype in association with negative seroconversion of the COPT in R patients. The COPT reaction has been associated with the highly specific egg glycoprotein antigen w1, which shows a significant reduction in reactivity six months after treatment. IgG1 may thus play a main role in the response against the w1 antigen.

The Last Fifteen Years of Schistosomiasis in Venezuela: Features and Evolution

Control of schistosomiasis in Venezuela has been a topic of major interest and controversy among the metaxenic parasitosis. A small area of transmission of approximately 15,000 km2 was thought to be eradicated some years ago. However, some epidemiological characteristics of our transmission area have limited the success on the way toward eradication. Since 1945, when the Schistosomiasis Control Program started, the prevalence in the endemic area has decreased from 14% in 1943 to 1.4% in 1996. Until 1982, the surveillance of active cases was based on massive stool examination. Since then, the Schistosomiasis Research Group (SRG) recommended the additional use of serologic tests in the Control Program and the selective or massive chemotherapy depending on serological and parasitological prevalence of each community. At present, the real prevalence is underestimated due to the fact that approximately 80% of the individuals eliminate less than 100 eggs/g of feces. Those persons could be responsible for the maintenance of the foci going on and therefore limiting the impact of the control measures. Efforts of the SRG are being oriented toward improvement of immunodiagnostic tests by using defined antigens (enzymes) and chemically synthesized peptides, derived from relevant molecules of the parasite, either for antibodies or antigens search. On the other hand, introduction of snail competitors has been a biological weapon in the control of the intermediate host in certain areas. However, the recent reinfestation of water courses by Biomphalaria glabrata, the increased prevalence in some areas, together with important administrative changes at the Control Program of the Minister of Health, have arisen new questions and doubts, challenging the eradication strategy proposed during the last decade.

Presence of Panstrongylus rufotuberculatus (Champion, 1899) (Hemiptera: Reduviidae: Triatominae) in Argentina

Panstrongylus rufotuberculatus is reported for the first time in Argentina. Four adults were attracted by the light of human dwellings in Calilegua National Park, Jujuy, at 1150 masl within the subtropical humid forest. The individuals were similar to those described in the literature. The epidemiological significance of this species is very low in the area, although deforestation might increase its role in the transmission of Trypanosoma cruzi.

Procedures to characterize and study P2Z/P2X7 purinoceptor: flow cytometry as a promising practical, reliable tool

The expression of P2Z/P2X7 purinoceptor in different cell types is well established. This receptor is a member of the ionotropic P2X receptor family, which is composed by seven cloned receptor subtypes (P2X1 - P2X7). Interestingly, the P2Z/P2X7 has a unique feature of being linked to a non-selective pore which allows the passage of molecules up to 900 Da depending on the cell type. Early studies of P2Z/P2X7 purinoceptor were exclusively based on classical pharmacological studies but the recent tools of molecular biology have enriched the analysis of the receptor expression. The majority of assays and techniques chosen so far to study the expression of P2Z/P2X7 receptor explore directly or indirectly the effects of the opening of P2Z/P2X7 linked pore. In this review we describe the main techniques used to study the expression and functionality of P2Z/P2X7 receptor. Additionally, the increasing need and importance of a multifunctional analysis of P2Z/P2X7 expression based on flow cytometry technology is discussed, as well as the adoption of a more complete analysis of P2Z/P2X7 expression involving different techniques.

A theoretical model of the tridimensional structure of Bacillus thuringiensis subsp. medellin Cry 11Bb toxin deduced by homology modelling

Cry11Bb is an insecticidal crystal protein produced by Bacillus thuringiensis subsp. medellin during its stationary phase; this ¶-endotoxin is active against dipteran insects and has great potential for mosquito borne disease control. Here, we report the first theoretical model of the tridimensional structure of a Cry11 toxin. The tridimensional structure of the Cry11Bb toxin was obtained by homology modelling on the structures of the Cry1Aa and Cry3Aa toxins. In this work we give a brief description of our model and hypothesize the residues of the Cry11Bb toxin that could be important in receptor recognition and pore formation. This model will serve as a starting point for the design of mutagenesis experiments aimed to the improvement of toxicity, and to provide a new tool for the elucidation of the mechanism of action of these mosquitocidal proteins.