Splenomegaly in relation to Schistosoma mansoni egg counts: a population based study

A cross: sectional survey on schistosomiasis was done in Comercinho (Minas Gerais State, Brazil), a town with 1474 inhabitants. Stool (Kato-Katz method) and physical examinations were done on 90% of the population and on 84% of the individuals over 2 years of age, respectively. The ecological and individual (case-control) analysis were used to investigate the relation between splenomegaly and S. mansoni egg counts in different age groups. In the ecological analysis there was a clearly correspondence between higher geometric mean of eggs and higher percentage of splenomegaly in the age groups 5-9 and 10-12 years. In the individual analysis it was found that only in the youngest individuals (5-8 or 5-9 years old) the splenomegaly was related with higher mean egg counts in the feces, having been a tendency to the decrease of excretion of eggs in patients with splenomegaly as the age increased. These results strongly suggest that the ecological data are' better indicator of the severity of schistosomiasis in endemic areas, as the decrease of the egg excretion in patients with splenomegaly may be a confounding variable for the individual analysis.

Prevalence of antibody to hepatitis B virus in an urban population of northeast Brazil

A sample of 1,288 inhabitants of Salvador, Bahia, Brazil, were submitted to the determination of anti-HBs using radioimmunoassay procedure, and analysed according to age, sex and income. Overall prevalence of anti-HBs was 11,8%. ranging from 6,7% among children aged less than three years old to 26,1% among those aged 30 years and older. Males presented prevalence of anti-HBs similar to female individuals, and those with a higher income showed frequencies of anti-HBs greater than those with a lower income level. The following conclusions were drawn: The high prevalence of anti-HBs observed among children suggests early contact with hepatitis B virus, possibly due to vertical transmission and intrafamiliar dissemination of the disease; the frequency of anti-HBs increases with age; the lower prevalence of anti-HBs among those with low income suggests that this group may present higher prevalence of carriers of the hepatitis B virus surface antigen.

Paracoccidioidomycosis: a sequential histopathologic study of lesions in experimentally-infected rats

Female albino rats were used for the sequential histopathological study of experimental paracoccidioidomycosis. The animals were inoculated intraperitoneally with a strain of Paracoccidioides brasiliensis in the yeast-like phase, and sacrificed at given intervals from 1 to 168 days after inoculation; each animal received an inoculum of 4 x 10(6) cells in 0.8 ml of saline. The control group received saline containing scrapings of the culture medium. Tissue from the inoculation site was examined. The cellular population, the extracellular matrix, and the presence and characteristics of fungi were analysed in the inflammatory granulomatous process by light microscopy. The results allowed to separate the kinetic of the inflammatory response into three stages: 1) neutrophilic or macrophagic-neutrophilic; 2) pre-granulomatous; 3) granulomatous. Synthesis of the extracellular matrix began with the depositing of fibrin-like material, and increased gradually with deposits of collagen, proteoglycans, and glycoproteins. Parasites were present in all of the examined periods. Recurrences of the disease were clearly shown through the concurrence of recently-formed granulomas with older granulomas, implying that this type of granulomatous process does not eliminate the disease, nor is it able to limit fungal dissemination over a prolonged period of time.

Schistosomiasis mansoni in the municipality of Pedro de Toledo (São Paulo, Brazil) where the Biomphalaria tenagophila is the snail host: I - Prevalence in human population (

Due to the scarce information about the epidemiological features of schistosomiasis in which the vector is Biomphalaria tenagophila, an investigation was carried in Pedro de Toledo in 1980 where such peculiarity is observed. Stool examinations (Kato-Katz method) were performed in 4,741 individuals (22.8% positive to Schistosoma mansoni eggs) of this 583 had previously received chemoterapy and 4,158 remainders, untreated. The schistosomiasis prevalence in those two groups where respectively 31.7% and 21.6%. Epidemiological investigation showed that 83.6% were autochthonous cases from the studied area: the autochthonous prevalence rate, and the intensity of infection in the untreated autochthonous cases were higher in males than in females; the intensity in the latter untreated group was low, 58.5 eggs/g feces (geometric mean). Moreover, according to the age groups the intensity of infections correlated well (r s = 0.745) with the prevalence rates. Schistosomiasis was verified to occur mostly during the leisure time and by the use of water streams for housework in rural zone. Only 0.4% out of 1,137 snails was positive for S. mansoni cercariae, apparently unchanged from the 1978 study when the human prevalence was 12.0%. The studied area presented differences and similarities in relation to the other Brazilian areas were the main intermediate host is B. glabrata.

A serological investigation of rotavirus infections in a shanty town population in Rio de Janeiro

The presence of antibodies against rotavirus was investigated by enzyme immunosorbent assay (ELISA) in two distinct groups of children living in a shanty town in Rio de Janeiro. One hundred and thirty six plasma samples were randomly collected from children of 0 to 33 months (first group) and 255 serum samples were collected from other 85 children at ages of 2, 6 and 9 months (second group). A high percentage of antibodies were found in the newborn children and this rate decreased progressively until the age of 11 months, after which it increased again. At the age of 7 months, geometric mean antibody titers increased indicating that infection had occurred.

Enzyme linked immunosorbent assay: determination of anti-adenovirus antibodies in an infant population

In order to define an accurate assay for anti-adenovirus antibody detection, a recently developed ELISA was compared with IFA and CF. On 58 sera, the ELISA was more sensitive than both CF and IFA, which showed relative sensitivities of 63% and 94%, respectively. It was not possible to determine the exact specificity of the tests because of the lack of a gold standard. Furthermore, the ELISA was used to define the prevalence of adenovirus antibodies in 116 infants between 1 and 24 months old (mean 7.28). The data showed that maternal antibodies waned by the age of 5 to 6 months and that more than 80% of the children had been infected by adenoviruses by the age of 10 months.

B and Delta hepatitis virus infection in a population of West Africa

Among the 424 serum samples examined, the prevalence of hepatitis virus infection turned out to be 89.6%, with 15.6% of HBsAg positivity. Some of the samples belonged to an afferent population and some other to workers of a West Africa rural hospital (Pop. Rep. of Benin). 27.3% of the positive subjects presented active replication of the virus, shown by the presence of HBeAg. Among the HBcAb positive subjects the anti-delta antibodies showed a positivity frequency of 19.7%. HBsAg presence in 15% of pregnant women suggested the importance of HBV mother-foetal transmission in the district. The examined results can be compared with those obtained in other African areas, with similar socio-economic conditions.

The frequency of blood-born viral infections in a population of multitransfused Brazilian patients

The frequency of viral markers for hepatitis B (HBV) and C (HCV), human immunodeficiency virus-1 (HIV-1) and human T-lymphotropic virus-1 (HTLV-1) was evaluated in 32 Brazilian ß-thalassemia multitransfused patients. Additionaly the serum concentrations of ferritin and alanine aspartate transaminase (ALAT) were determined. The results show a high prevalence of markers of infection by HBV (25.0%) and HCV (46.8%) and a low prevalence of markers for HIV-1 and HTLV-1. No correlations were demonstrated between the presence of the hepatitis markers and the number of units transfused or the serum concentrations of ferritin and ALAT.

Acute respiratory infections in children from a deprived urban population from Uruguay

To obtain base line data on incidence, duration, clinical characteristics and etiology of acute respiratory infections (ARI), 276 children from deprived families living in Montevideo were followed during 32 months. The target population was divided into two groups for the analysis of the results: children aged less than 12 months and those older than this age. During the follow-up period 1.056 ARI episodes were recorded. ARI incidence was 5.2 per child/year. It was 87% higher in infants than in the older group, as was the duration of the episodes. Most of the diseases were mild. Tachypnea and retractions were seldom observed, but 12 children were refered to the hospital, and 2 infants died. Viral etiology was identified in 15.3% of the episodes. RSV was the predominant agent producing annual outbreaks. Moderate to heavy colonization of the upper respiratory tract by Streptococcus pneumoniae (32.3%) and Hemophilus sp. (18.9%) was recorded during ARI episodes. This community-based study furnish original data on ARI in Uruguay. It enabled to asses the impact of these infections on childhood.

Evaluation of different methods for Plasmodia detection, in well defined population groups in an endemic area of Brazil

In Brazil, more than 500,000 new cases of malaria were notified in 1992. Plasmodium falciparum and P.vivax are the responsible species for 99.3% of the cases. For adequate treatment, precoce diagnosis is necessary. In this work, we present the results of the traditional Plasmodia detection method, thick blood film (TBF), and the results of alternative methods: Immunofluorescence assay (IFA) with polyclonal antibody and Quantitative Buffy Coat method (QBC)® in a well defined population groups. The analysis were done in relation to the presence or absence of malaria clinical symptoms. Also different classes of immunoglobulins anti-P.falciparum were quantified for the global analysis of the results, mainly in the discrepant results. We concluded that alternative methods are more sensitive than TBF and that the association of epidemiological, clinical and laboratory findings is necessary to define the presence of malaria.

Prevalence of rubella antibodies in a non-immunized urban population, São Paulo, Brazil

The prevalence of rubella antibodies was evaluated through a ramdom Seroepidemiological survey in 1400 blood samples of 2-14 year old children and in 329 samples of umbilical cord serum. Rubella IgG antibodies were detected by ELISA, and the sera were collected in 1987, five years before the mass vaccination campaign with measles-mumps-rubella vaccine carried out in the city of São Paulo in 1992. A significant increase in prevalence of rubella infection was observed after 6 years of age, and 77% of the individuals aged from 15 to 19 years had detectable rubella antibodies. However, the seroprevalence rose to 90.5% (171/189) in cord serum samples from children whose mothers were 20 to 29 years old, and reached 95.6% in newborns of mothers who were 30 to 34 years old, indicating that a large number of women are infected during childbearing years. This study confirms that rubella infection represents an important Public Health problem in São Paulo city. The data on the seroprevalence of rubella antibodies before the mass vaccination campaign reflects the baseline immunological status of this population before any intervention and should be used to design an adequate vaccination strategy and to assess the Seroepidemiological impact of this intervention.

Anti-HCV related to HCV PCR and risk factors analysis in a blood donor population of Central Brazil

Data concerning HCV infection in Central Brazil are rare. Upon testing 2,350 voluntary blood donors from this region, we found anti-HCV prevalence rates of 2.2% by a second generation ELISA and 1.4% after confirmation by a line immunoassay. Antibodies against core, NS4, and NS5 antigens of HCV were detected in 81.8%, 72.7%, and 57.5%, respectively, of the positive samples in the line immunoassay. HCV viremia was present in 76.6% of the anti-HCV-positive blood donors. A relation was observed between PCR positivity and serum reactivity in recognizing different HCV antigens in the line immunoassay. The majority of the positive donors had history of previous parenteral exposure. While the combination of ALT>50 IU/l and anti-HBc positivity do not appear to be good surrogate markers for HCV infection, the use of both ALT anti-HCV tests is indicated in the screening of Brazilian blood donors.

Serological findings during a measles outbreak occurring in a population with vaccine coverage

From March 1991 to April 1992, serum samples for IgM detection were collected from 112 clinical measles cases reported to the Health Department of Niterói, State of Rio de Janeiro. The positivity exceeded 90% for specimens collected from the 5th to the 29th day after the onset of the disease. After day 30 a decline in IgM detection was observed, although positivity has been detected up to 90 days after the onset of the symptoms. Forty-four patients (48.9%) with an IgM response had a history of prior measles vaccination. In 5 of the 22 measles-IgM negative cases the infection was due to other agents (rubella: 4 cases, dengue: 1 case). These results show that sensitivity of the test employed for confirming suspected measles cases is high, even in vaccinated patients.

Population dynamics and biting rhythm of the anthropophilic sandfly Lutzomyia cruciata (Diptera: Psychdidae) in Southeast, Mexico

Sandflies attracted by human bait were caught in an endemic focus of localized cutaneous leishmaniasis in the state of Campeche, Mexico. Catches were carried out monthly from February 1994 to January 1995 between 18:00 and 22:00 h. Lutzomyia cruciata was the only species caught. The highest population peak of Lu. cruciata was found in March with lesser peaks in February, December 1994, and January 1995. Maximum biting rate of Lu. cruciata was found between 18:00 and 19:00 h. The host-seeking females of Lu. cruciata were directly related to levels of humidity between 88 and 100%. Low and high temperature had a negative effect upon Lu. cruciata activity. The possible role of Lu. cruciata as vector of leishmaniasis in the state of Campeche, Mexico is discussed.

Histoplasmin and paracoccidioidin skin reactivity in infantile population of Northern Argentina

In order to estimate ages at which etiological agents of systemic mycoses initiate infection, histoplasmin and paracoccidioidin skin tests were performed in 344 children of both sexes, between 2 and 15 years old. They were selected from a statistically significant population sample Gral. San Martín city (Northeast Argentina). Tests were read 48h after injection and considered positive if a 5 mm on larger induration was present. Circulating antibodies were also evaluated by agar gel immunodiffusion. The overall infection rate for H. capsulatum was 9.2%, belonging to children from 4 to 14 years old, without significant differences among sexes. Five children from 2 to 14 years old were positive to paracoccidioidin (1.6%). None of the children had specific antibodies neither signs of active mycosis. Results show H. capsulatum infection can be found from age 4, while for P. brasiliensis the lower limit was two years old. These findings may contribute to better knowledge on infantile fungal infection in a geographical region where no previous references can be found.