Comparative Histopathology of Biomphalaria glabrata, B. tenagophila and B. straminea with Variable Degrees of Resistance to Schistosoma mansoni Miracidia

A comparative histopathological study of three snails species - Biomphalaria glabrata, B. tenagophila and B. straminea - which had been infected with Schistosoma mansoni miracidia revealed similar qualitative features, consisting of areas of sporocyst proliferation and differentiation associated with reactive host reaction, at the time they were actively eliminating great number of cercariae. However, in specimens that were exposed to miracidia but failed to eliminate cercariae later on, different histopathological pictures were observed in different snail species. While B. glabrata exhibited frequent focal (granulomatous) proliferation of amebocytes in several organs, B. tenagophila and B. straminea only rarely showed such reactive changes, suggesting that the mechanism of resistance to miracidial infection probably follows different pathways in the snail species studied

Evaluation of the Molluscicidal Properties of Euphorbia splendens var. hislopii (N.E.B.) Latex: Experimental Test in an Endemic Area in the State of Minas Gerais, Brazil

Following the positive results obtained regarding the molluscicidal properties of the latex of Euphorbia splendens that were corroborated in laboratory and field tests under restricted conditions, a field study was conducted in experimental streams located in an endemic area. After recording the average annual fluctuations of vectors in three streams, a solution of E. splendens latex at 12 ppm was applied in stream A, a solution of niclosamide at 3 ppm that was applied in stream B and a third stream (C) remained untreated for negative control. Applications of E. splendens and niclosamide resulted in a mortality of 100% among the snails collected in the streams A and B. No dead snails were found in the negative control stream. A monthly follow-up survey conducted during three consecutive months confirmed the return of vectors to both experimental streams treated with latex and niclosamide. This fact has called for a need to repeat application in order to reach the snails that remained buried in the mud substrate or escaped to the water edge, as well as, newly hatched snails that did not respond to the concentration of these molluscicides. Adults snails collected a month following treatment led us to believe that they had migrate from untreated areas of the streams to those previously treated

Chronic carriers of hepatitis B surface antigen in an endemic area for schistosomiasis mansoni in Brazil

Data on the association of schistosomiasis and hepatitis B in field-based studies are scarce. Two areas have been selected for this study: i) Queixadinha, endemic for schistosomiasis, with a population of 693 individuals, and ii) Capão, a control non-endemic area, with 515 inhabitants. Sera of all individuals in both areas were tested for hepatitis B infection, yearly, from 1994 to 1997. In the first area hepatitis B was found in 32.1% of children up to one year old and reached a peak of 68.7% in the age range of 15 to 19 years. In the control area the prevalence of hepatitis B was under 5% up to 19 years of age and the highest prevalence was observed in adults over 45. HBsAg was detected in 9.4% of the individuals living in the endemic area for schistosomiasis and in 1.4% of the controls (OR=4.98; 95%CI=3.7-6.7). The index of chronicity of HBsAg was not statistically different in the studied areas (8.1% x 7.3%; OR = 1.09; 95%CI= 0.42-3.03), nor was it different for people with and without schistosomiasis in Queixadinha (8.7% x 7.0%). We conclude that the Schistosoma mansoni infection has not altered the course of hepatitis B in the studied area.

Prognosis of schistosomiasis mansoni patients infected with hepatitis B virus

A clinical study on the evolution of patients with schistosomiasis mansoni has been conducted since 1983 at the outpatient clinic of the Infectious and Parasitic Disease Service in the Clementino Fraga Filho University Hospital in Rio de Janeiro, Brazil, comparing prevalence of positive tests for HBsAg, anti-HBsAg, and anti-HBc among patients infected with Schistosoma mansoni coming from various regions of Brazil and with different clinical forms of the disease. A non-significant predominance of HBsAg, anti-HBsAg, and anti-HBc was detected among patients with the hepatosplenic form of schistosomiasis, who presented a more severe clinical evolution with a higher frequency of hematemesis and/or melena, in addition to the development of macronodular cirrhosis and a worse prognosis as compared to patients with the toxemic form, schistosomiasis-infection and the hepatointestinal form.

The Epidemiological Impact of Antimeningococcal B Vaccination in Cuba

The incidence of invasive meningococcal disease (IMD) before (1984-1988) and after (1989-1994), a nationwide intervention with VA-MENGOC-BC vaccination started in 1989, was compared. The prevaccination period incidence density (ID> 8.8/ 105 year-person) was higher than the postvaccination ID (ID< 6.5/ 105 year-person). The percentage proportional differences from the start to the end of each period of ID in the vaccinal period was higher (87%) than the prevaccinal (37%) with significant differences among vaccinated groups (< 25 years old). A break-point (Chow test) was confirmed by the decrease in the ID between 1989 and 1990 in children under 1 year old, 5-9, 10-14, 15-19 and 50-54 years. Comparison of ID using maps showed a decrease in IMD in all municipalities during the postvaccination period. These findings support the epidemiological impact of VA-MENGOC-BC vaccination in the reduction of IMD morbidity.

Hepatitis B virus exposure in human immunodeficiency virus seropositive Cuban patients

In order to estimate the prevalence of serological markers of exposure to Hepatitis B Virus (HBV), 295 subjects were selected at random from the National Registry of human immunodeficiency virus positive subjects. Evidence of exposure to HBV was defined as: testing Hepatitis B surface antigen (HBsAg) and anti-Hepatitis B core antigen (anti-HBc) positive or anti-HBc positive only. Overall, 133 (45.5%) were positive for anti-HBc and 15 (5.1%) resulted positive to HBsAg. Significant statistical association was found between male sex and exposure to HBV (p<0.01). Homosexual or bisexual behavior was found to be strongly associated to HBV exposure (p<0.001). In conclusion, the prevalence of HBV serological markers is higher in Cuban HIV positive subjects compared to the Cuban general population.

Respiratory syncytial virus groups A and B in Porto Alegre, Brazil, from 1990 to 1995 and 1998

We analyzed the respiratory syncytial virus (RSV) groups and their epidemiological pattern that were detected over the course of seven years in southern Brazil. The two RSV groups co-circulated each year, but frequencies of groups A and B varied both between and within yearly outbreaks. In 1991, group A predominated over group B (p=0.0016). RSV outbreaks analyzed showed a temperature-dependent pattern and no association with rainfall, similarly to other countries from southern South America. Knowledge of the variants is important in terms of both diagnosis and definition of a vaccine composition.

Prevalence of antibodies to hepatitis B core antigen in blood donors in the middle west region of Brazil

The prevalence of antibodies to hepatitis B core antigen in 552 prime blood donors was of 9.4%. The majority (71.2%) has antibodies to hepatitis B surface antigen. The hepatitis B surface antigen was present in 0.7%, all of them antibodies to hepatitis B core antigen positive.

Hepatitis B infection among patients attending a sexually transmitted diseases clinic in Rio de Janeiro, Brazil

Hepatitis B virus (HBV) has a low endemicity in Rio de Janeiro, Brazil. Sexual transmission must play an important role in this virus, but the prevalence and risk factors have never been properly investigated. The aim of this paper is to determine the prevalence and risk factors for HBV infection in patients attending a Sexually Transmitted Diseases Clinic of the Universidade Federal Fluminense, from the State of Rio de Janeiro, Brazil. In a retrospective study, HBV seroprevalence was investigated in 440 patients. Serum of each patient was assayed for antibodies against hepatitis B core antigen (anti-HBc), hepatitis B surface antigen (HBsAg) and antibodies against hepatitis B surface antigen (anti-HBs). Demographic and risk factor data were extracted from clinic notes. The overall seroprevalence of exposure markers for HBV (anti-HBc, HBsAg and anti-HBs) were 13%, 3.4% and 8.5% respectively. Homo/bisexual behaviour, anal intercourse, HIV infection, positive serology for syphilis and blood transfusion were predictors of the HBV exposure. Among demographic data, age and place of birth were associated with the anti-HBc seropositivity.

Prevalence of hepatitis B and C virus markers among malaria-exposed gold miners in Brazilian Amazon

Hepatitis B and C virus markers were assessed during a survey on malaria in gold mine camps in southern Brazilian Amazon in order to identify risk factors associated to these viral diseases. The study comprised 520 subjects, most of them were gold miners. Missing subjects totaled 49 (8.6%). Among these 520, 82.9% had HBV markers and 7.1% were HBsAg positive. Previous hospitalization, surgery, sexually transmitted diseases and incarceration were quite common among surveyed people, but there is no association between total HBV markers and these factors. On other hand, HBsAg was independently associated to history of sexually transmitted diseases and history of surgery after adjustment. The most frequent HBsAg subtypes identified, adw2 (59%), predominates in populations of Northeast Brazil. The most surveyed people were immigrants coming from that area suggesting that immigrants carried HBV themselves to the study area. Immunoblot (RIBA) confirmed-anti-HCV were found in 2.1%. The only variable associated to anti-HCV in multivariate analysis was illicit intravenous drug. Lack of HCV infection in subjects with such a high HBV markers prevalence reinforces the opinion that HCV is transmitted by restricted routes when compared to HBV. Furthermore, gold miners in Amazon may be considered as a risk group for HBV infection, but not for HCV.

Detection of Hepatitis B Virus Antigens in Paraffin-embedded Liver Specimens from the Amazon Region, Brazil

Hepatic viscerotomy of paraffin-preserved old specimens, collected in the period from 1934 to 1967, were analyzed by immunohistochemical assays to detect hepatitis B, hepatitis D, dengue and yellow fever virus antigens. The material belongs to the Yellow Fever Collection, Department of Pathology, Instituto Oswaldo Cruz, Rio de Janeiro, Brazil and the cases were diagnosed at that time according to clinical aspects and histopathological findings reporting viral hepatitis, yellow fever, focal necrosis and hepatic atrophy. From the 79 specimens, 69 were collected at the Labrea Region and the other 10 in different other localities in the Amazon Region. The five micra thick histological slices were analyzed for the presence of hepatitis B surface antigen (HBsAg) and hepatitis B core antigen (HBcAg) by immunoperoxidase technique. An immunofluorescence assay was applied to the detection of hepatitis D, yellow fever and dengue virus antigens. Nine (11.4%) histological samples were HBsAg reactive and 5 (6.3%) were HBcAg reactive. The oldest reactive sample was from 1934. Viral antigens related to the other pathologies were not detected in this study. Our results confirm that the methodology described may be used to elucidate the aetiology of hepatitis diseases even after a long time of conservation of the specimens.

Relation between Hepatitis B Carrier Status and Antibody against Synthetic Plasmodium falciparum Erythrocyte Surface (pf155 - RESA) Antigen

A survey on Plasmodium infection was carried out in gold mine camps located in the Brazilian Amazon. Antibody against P. falciparum ring-infected erythrocyte surface antigen (RESA) was quantified by an enzyme-immunoassay in order to assess P. falciparum exposure. Hepatitis B, a common infection in this area, was also investigated by serologic markers. Among 520 sampled subjects, 517 (99.4%) admitted previous symptomatic malaria, 106 (20.4%) had positive thick smears for malaria, 82.9% had HBV markers, and 7.1% were HBsAg positive. Anti-RESA titers was significantly lower in HBV carriers than in people with resolved HBV infection suggesting that the anti-RESA immune response could be supressed by HBV carrier status. Moreover, immunedeficient responses to both infections may take place in some subjects causing concomitant lower anti-RESA response and incapacity to clear HBV.

Isolation and Identification of 9-methylgermacrene-B as the Putative Sex Pheromone of Lutzomyia cruzi (Mangabeira, 1938) (Diptera: Psychodidae)

Lutzomyia (Lutzomyia) cruzi has been named as a probable vector of Leishmania chagasi in Corumbá, Mato Grosso do Sul, Brazil. Taxonomically L. cruzi is closely related to the L. longipalpis species complex. Females of L. cruzi and L. longipalpis are morphologically indistinguishable and associated males must be examined carefully to confirm identifications. Chemical analysis hexane extracts of male L. cruzi has revealed the presence of a 9-methylgermacrene-B (C16), a homosesquiterpene (mw 218) previously shown to be the sex pheromone of one of the members of the L. longipalpis species complex.