Alexandre B. de Carvalho

Epidemiological study of bancroftian filariasis in Recife, Northeastern Brazil

Wuchereria bancrofti in Pernambuco was first documented in 1952 (Azevedo & Dobbin 1952), and since then it has been reported in surveys carried out in selected areas of Recife. Several surveys were carried out from 1981 to 1991 by SUCAM. In the 1985 SUCAMs report the disease is considered under control. The CPqAM Filariasis Research Program was established in 1985 and a filarial survey was carried out in the town of Olinda, Greater Recife. In order to verify the real epidemiological situation, a study was conducted in the city of Recife. 21/36 of the Special Zones of Social Interest (ZEIS), were randomly selected for the present study. From 10,664 persons screened, 683 were positive and the prevalence rate for microfilaraemia (mf) varied from 0.6% to 14.9%. A mean mf prevalence of 6.5%, showed that the infection occurs in a wide geographic distribution in Greater Recife and that the intensity of transmission is a real and potential threat to public health in affected communities. Mf rate among males and females differed significantly. Due to the rapid increase in population, unplanned urban settlements, poor sanitary facilities and the favorable geographical conditions to the development of the vector, filariasis may actually be increasing in Recife.

Intestinal Helminthiasis and Anaemia in Youngsters from Matriz da Luz, District of São Lourenço da Mata, State of Pernambuco, Brazil

A group of youngsters (4-18 years old) in northeast Brazil was studied to establish the prevalence of anaemia and intestinal parasitism, as well as to analyze the correlation between them. Two criteria were used to determine the state of anaemia, the level of haemoglobin and the mean of corpuscular volume. The first was considered a single criterion and the second an associated criteria, used in an attempt to correlate anaemia with iron deficiency. The prevalence of intestinal parasitism was 93%, while the prevalence of anaemia was 43.1% and 16.1% according to the criteria employed (single or associated respectively). Anaemia was significantly associated with both sex and age. No significant statistical difference was observed when the association was made between each parasite and anaemia even with those more related to anaemia.

Immunocytochemical study of Peyer's patches follicular-associated epithelium in the marsupial, Didelphis albiventris

The lack of probes defining leukocyte subpopulations has restricted ontogenetic studies of the opossum gut. We report for the first time the organization of the gut cellular immune components using species cross-reactive antibodies. Mouse monoclonal antibodies against human HLA-DR were used together with immunocytochemistry to demonstrate MHC class II-like antigens in the opossum Peyers patches (PP). Positive staining was obtained in the M cell and enterocytes comprising the follicular-associated epithelium (FAE). Rabbit polyclonal antibody against human CD3 stained opossum thymocytes and T-cell dependent areas of spleen, lymph node, and PP interfollicular zones, but failed to stain intraepithelial lymphocytes in the FAE. In contrast rabbit polyclonal antibody against human IgA stained B-cell immunocytes and plasma cells present in the M-cell lateral invaginations. It is surmised that B-cell activation could occur in the opossum M-cell niches by thymus independent antigens, bypassing T-helper-cell function.

The use of non-specific immunopotentiators in experimental Trypanosoma cruzi infection

The effects of levamisole, isoprinosine and Corynebacterium parvum on Trypanosoma cruzi (Y strain) experimental infection of mice were studied. In prophylactic treatment these drugs reduced the peak of parasitaemia, and had no apparent effect on mortality rate or on histopathological and electrocardiographic findings. Levamisole and isoprinosine had no effect when used after infection. Electrocardiograms were obtained from all chronic chagasic mice. The most frequent changes were left atrial overload and first degree atrio-ventricular block. These findings became more frequent the longer the animals survived. The net effect of the non-specific immunopotentiators seems to depend on several factors: host immune state, severity of infection, dose and timing of drug administration. This probably explains the variable published results and the paradoxical findings of different laboratories.

Perfil epidemiológico da filariose linfática em crianças residentes em áreas endêmicas

OBJECTIVE Lymphatic filariasis still represents a major public health problem in the city of Recife. In spite of the fact that previous surveys had already shown high frequency of microfilaraemia in pediatric population, the prevalence of filarial disease and the microfilaraemic pattern of this group were unknown. This paper describes the clinical-epidemiological pattern of filariasis in children and adolescents living in two highly endemic areas of Recife. METHODS The parasitological survey was done through a census carried out between December 1990 and July 1991. Thick drop technique (45 micro l) was performed on a total of 1,464 children and adolescents between the ages of 5 and 14, of whom 967 were submitted to clinical examination. Positive cases had their blood recollected (60 micro l) to measure the microfilaraemic density. RESULTS The microfilaraemia prevalence was 6.4 %. In the age groups of 5 to 9 and 10 to 14 a microfilaraemia prevalence of respectively 4.6% and 8.3% was observed. The microfilaraemic density varied from 3 to 864 microfilariae per 60 microl of blood, there having been no statistically significant difference between the sexes and age groups (p<0.05). 6 cases (0.6 %) of acute filarial disease and 11 of chronic filarial disease (1.1%) were identified, hydrocele being the principal manifestation found. Lymphadenopathy was found in 22% of the children, statistical association with microfilaraemia being observed (p<0.001). CONCLUSIONS The results of the parasitological survey show the strong presence of children in the contingent of microfilaraemic individuals, indicating an early and intense exposure to filariasis in the population studied.

Isolation ofTrypanosoma cruzi from blood by histopaque and continuous percoll gradient centrifugations

Separation of the blood forms of trypanosomes from the blood of infected animals is difficult, especially in the case ofTrypanosoma cruzi Y strain. Two procedures to isolate the Y strain blood forms of T.cruzi using polyvinyl pyrrolidone-coated silica (percoll) and histopaque are reported in this study. The recovery rates of parasites were 16±5 and 68±16%, respectively. The parasites isolated by these methods presented normal motility and morphology and were infective to albino mice with prepatent periods, parasitemia curves, and polymorphism patterns during the infection that were similar to those of control parasites. In addition, the preservation of surface antigens was confirmed by immunocytochemical studies.

Study of humoral immune response in mammals immunized with Plasmodium falciparum antigenic preparations

Six Plasmodium falciparum protein fractions, isolated under reducing conditions, were used to immunize mice, rabbits and the squirrel monkey Saimiri sciureus. Five or seven subcutaneous injections of each antigenic preparation, in conjunction with Freunds complete or incomplete adjuvants, were administered. This led to the development of specific antibodies detected by IFAT, ELISA or immunoblotting which inhibited merozoite reinvasion in in vitro P. falciparum cultures. This activity seems to be associated with rhoptry proteins contained in fractions Pf F2 and Pf F4.

A simple method for detection of monoclonal isotypes

A simple rapid method of enzyme labeled anti-isotype assay (ELIA) for detection of monoclonal isotype on hybridoma cells is proposed. This alternative method was first carried out on hybridoma cell lines 147C11 and 257C11 produced againstTrypanosoma cruzi and male accessory secretion ofPanstrongylus megistus, respectively. The monoclonal antibodies produced by these hybridoma were characterized by this method as IgM (147C11) and IgGl (257C23) isotypes, allowing evaluation of isotype without having to wait until the concentration of antibody present in the supernatant itself rises. Results were confirmed by Ouchterlony immunodiffusion. The proposed method offers the advantages of a permanent rapid procedure for light microscopy.