Risk factors and prevalence of antibodies against hepatitis A virus (HAV) in children from day-care centers, in Goiania, Brazil

A seroepidemiologic survey about hepatitis A virus (HAV) infection was carried out in a group comprising 310 children, ranging in age from 3 months to 9 years, from day-care centers, in Goiania, a middle sized city in the central region of Brazil. The biomarkers employed in the investigation of previous infection include total IgG and IgM anti-HAV antibodies, and for the detection of more recent infection, IgM anti-HAV antibodies were analyzed. The study was performed in 1991 and 1992. According to the results, 69.7% of the children presented total IgG/IgM anti-HAV antibodies, with 60% of the group in the age range of 1 to 3 years. Among 10 day-care centers analyzed, the prevalence of the biomarker IgM anti-HAV was 3.2%, with an uniform distribution of the cases in the group of children ranging in age from 1 to 4 years. Multi-variate analysis was performed to investigate the sociodemographic factors that could influence the results. It was verified that the risk for the infection increased with the length of the attendance in the day-care centers, i.e., the risk for children with attendance of one year or more was 4.7 times higher, when compared with children with one month attendance (CI 95% 2.3-9.9). According to the results, hepatitis A is an endemic infection in day-care centers in the study area. The length of attendance in the day-care settings was demonstrated to be a risk factor for the HAV infection. Such findings suggest that if hepatits A vaccination becomes available as a routine policy in our region, the target group should be children under one year. Moreover, those children should receive the vaccine before they start to attend the day-care centers.

Hyperimmune antirabies sera titration by standard mouse neutralization and counterimmunoelectrophoresis tests, comparing results of different laboratories

To determine the rabies antibody level of twenty-four hyperimmune equine sera, Standard Mouse Neutralization (SMN) and Couterimmunoelectrophoresis (CIE) tests were carried out, both at the Instituto Butantan (IB) and Instituto Panamericano de Protección de Alimentos y Zoonosis (INPPAZ). Statistical analysis has shown a correlation (r) of 0.9317 between the SMN and CIE performed at the IB, while at the INPPAZ it scored 0.974. Comparison of CIE data of both laboratories yielded a correlation of 0.845. The CIE technique has shown to be as sensitive and efficient as the SMN in titrating antirabies hyperimmune equine sera. Based on CIE results, a simple, rapid and inexpensive technique, tilers of sera antibody can be reliably estimated in SMN test.

Resistance of Streptococcus pneumoniae to antimicrobials in São Paulo, Brazil: clinical features and serotypes

To study resistance to antimicrobials, serotypes and clinical features of S. pneumoniae in S. Paulo, Brazil, 50 patients with a positive culture were evaluated: 7 were considered carriers and 43 had pneumococcal infections. Pneumonia and meningitis were the most commom infections. Mortality was 34% and underlying diseases were present in 70%. Relative resistance to penicillin occurred in 24% and complete resistance was not detected. Resistance to tetracycline was 32% and to sulfamethoxazole/trimethoprim 32%; one strain had intermediate susceptibility to erythromycin; no resistance was present for chloramphenicol, rifampin or vancomycin. Resistance to at least one of the drugs tested occurred in 62%. Results by the E-test for penicillin were similar to those by the agar dilution method. There were 24 different serotypes and 74% of the strains belonged to the 23-valent vaccine including all the penicillin-resistant strains. In this study S. pneumoniae caused severe infections and presented a high resistance rate to commonly used antimicrobials. Routine surveillance of resistance and the use of vaccination, as well as the restriction of inappropriate use of antimicrobials, are recommended in São Paulo, Brazil.

Measles antibody prevalence after mass immunization campaign in Niterói, State of Rio de Janeiro, Brazil

Three months after a mass vaccination campaign (coverage: 100%) against measles a random seroepidemiological survey was carried out in students aged 1 to 19 years old in the Municipality of Niterói, State of Rio de Janeiro. Blood samples were tested for measles antibodies by enzyme immunosorbent assay (EIA) and negative cases were tested again using hemagglutination inhibition (HI) and plaque reduction neutralization (PRN). Of the 798 samples tested by EIA, 718 (90.2%) were positive for measles antibodies. PRN test was more sensitive than EIA and HI in detecting measles specific antibodies. The total antibody prevalence increased from 90.2% to 93.2% when HI was employed in EIA negative specimens and to 98.9% when PRN was used. After the mass vaccination campaign a marked decrease in measles incidence was observed in the municipality studied, showing the effectiveness of the strategy used for measles control in developing countries.

Immune responses induced by a Leishmania (Leishmania) amazonensis recombinant antigen in mice and lymphocytes from vaccinated subjects

In the search for Leishmania recombinant antigens that can be used as a vaccine against American Cutaneous Leishmaniasis, we identified a Leishmania (Leishmania) amazonensis recombinant protein of 33 kD (Larp33) which is recognized by antibodies and peripheral blood leukocytes (PBL) from subjects vaccinated with Leishvacin ®, Larp33 was expressed in Escherichia coli after cloning of a 2,2 kb Sau3A digested genomic fragment of L. (L.) amazonensis into the pDS56-6 His vector. Immunoblotting analysis indicated that Larp33 corresponds to an approximately 40-kD native protein expressed in promastigotes of L.(L.) amazonensis and L. (Viannia) braziliensis. Northern blots of total RNA also demonstrated that the gene coding for this protein is expressed in promastigotes of the major lineages of Leishmania causing American Cutaneous Leishmaniasis. Larp33 induced partial protection in susceptible mouse strains (BALB/c and C57BL/10) against L. (L.) amazonensis after vaccination using Bacille Calmette-Guerin (BCG) as adjuvant. In vitro stimulation of splenocytes from BALB/c protected mice with Larp33 elicited the secretion of IL-2 and IFN-g, suggesting that a Th1 cell-mediated protective response is associated with the resistance observed in these mice. As revealed by its immunogenic and antigenic properties, this novel recombinant antigen is a suitable candidate to compose a vaccine against cutaneous leishmaniasis

Effect of b-Propiolactone treatment on the complement activation mediated by equine antisera

Reduction of complement activation through an alteration of the Fc fragment of immunoglobulins by b-propiolactone treatment was carried out in equine antisera raised against rabies virus, Bothrops venoms and diphtherial toxin. Results were evaluated by means of an anaphylactic test performed on guinea-pigs, and compared to the ones obtained with the same sera purified by saline precipitation (ammonium sulfate), followed or not by enzymatic digestion with pepsin. Protein purity levels for antibothropic serum were 184.5 mg/g and 488.5 mg/g in b-propiolactone treated and pepsin-digested sera, respectively. The recovery of specific activity was 100% and 62.5% when using antibothropic serum treated by b-propiolactone and pepsin digestion, respectively. The antidiphtherial and anti-rabies sera treated with b-propiolactone and pepsin presented protein purity levels of 5,698 and 7,179 Lf/g, 16,233 and 6,784 IU/g, respectively. The recovery of specific activity for these antisera were 88.8%, 77.7%, 100% and 36,5%, respectively. b-propiolactone treatment induced a reduction in complement activation, tested "in vivo", without significant loss of biological activity. This treatment can be used in the preparation of heterologous immunoglobulins for human use.

Meningococcal Disease Caused by Neisseria meningitidis Serogroup B Serotype 4 in São Paulo, Brazil, 1990 to 1996

A large epidemic of serogroup B meningococcal disease (MD), has been occurring in greater São Paulo, Brazil, since 1988.21 A Cuban-produced vaccine, based on outer-membrane-protein (OMP) from serogroup B: serotype 4: serosubtype P1.15 (B:4:P1.15) Neisseria meningitidis, was given to about 2.4 million children aged from 3 months to 6 years during 1989 and 1990. The administration of vaccine had little or no measurable effects on this outbreak. In order to detect clonal changes that could explain the continued increase in the incidence of disease after the vaccination, we serotyped isolates recovered between 1990 and 1996 from 834 patients with systemic disease. Strains B:4:P1.15, which was detected in the area as early as 1977, has been the most prevalent phenotype since 1988. These strains are still prevalent in the area and were responsible for about 68% of 834 serogroup B cases in the last 7 years. We analyzed 438 (52%) of these strains by restriction fragment length polymorphism (RFLPs) of rRNA genes (ribotyping). The most frequent pattern obtained was referred to as Rb1 (68%). We concluded that the same clone of B:4:P1.15-Rb1 strains was the most prevalent strain and responsible for the continued increase of incidence of serogroup B MD cases in greater São Paulo during the last 7 years in spite of the vaccination trial.

Duality of patterns in hepatitis a epidemiology: A study involving two socioeconomically distinct populations in Campinas, São Paulo state, Brazil

To evaluate the prevalence of antibodies against hepatitis A in two socioeconomically distinct populations, 101 and 82 serum samples from high and low socioeconomic groups, respectively, were analysed for the presence of IgG anti-HAV using a commercial ELISA. The prevalence in low socioeconomic level subjects was 95.0%, whereas in high socioeconomic subjects was only 19.6% (p<0.001). These data show a duality in Brazil: anti-HAV prevalence in low socioeconomic subjects is similar to that of developing countries, while in high socioeconomic subjects, a pattern typical of developed countries is found. The control of this infection in our country is primarily related to the improvement of sanitation, but especially for high socioeconomic level populations, the use of vaccination against hepatitis A is strongly advisable to avoid the occasional appearance of this disease in adults.

HEPATITIS B VIRUS INFECTION PROFILE IN CENTRAL BRAZILIAN HEMODIALYSIS POPULATION

Hepatitis B has proved to be a major health hazard in hemodialysis patients. In order to investigate the hepatitis B virus (HBV) infection profile in the hemodialysis population of Goiânia city - Central Brazil, all dialysis patients (N=282) were studied. The prevalence of any HBV marker (HBsAg, anti-HBs, and anti-HBc) was 56.7% (95% CI: 51.1-62.7), ranging from 33.3% to 77.7% depending on dialysis unit. HBV-DNA was detected in 67.6% and 88.2% of the HBsAg-positive serum samples, in 91.3% and 100% of the HBsAg/HBeAg-positive samples, and in 18.2% and 63.6% of the HBsAg/anti-HBe-reactive sera by hybridization and PCR, respectively. The length of time on hemodialysis was significantly associated with HBV seropositivity. Only 10% of the patients reported received hepatitis B vaccination. The findings of a high HBV infection prevalence in this population and the increased risk for HBV infection on long-term hemodialysis suggest the environmental transmission, emphasizing the urgent need to evaluate strategies of control and prevention followed in these units.

ADVERSE EFFECT VERSUS QUALITY CONTROL OF THE FUENZALIDA-PALACIOS ANTIRABIES VACCINE

We evaluated the components of the Fuenzalida-Palacios antirabies vaccine, which is till used in most developing countries in human immunization for treatment and prophylaxis. This vaccine is prepared from newborn mouse brains at 1% concentration. Even though the vaccine is considered to have a low myelin content, it is not fully free of myelin or of other undesirable components that might trigger adverse effects after vaccination. The most severe effect is a post-vaccination neuroparalytic accident associated with Guillain-Barré syndrome. In the present study we demonstrate how the vaccines produced and distributed by different laboratories show different component patterns with different degrees of impurity and with varying protein concentrations, indicating that production processes can vary from one laboratory to another. These differences, which could be resolved using a better quality control process, may affect and impair immunization, with consequent risks and adverse effects after vaccination. We used crossed immunoelectrophoresis to evaluate and demonstrate the possibility of quality control in vaccine production, reducing the risk factors possibly involved in these immunizing products.

Safety and immunogenicity of hepatitis B vaccine ButaNG in adults

Recombinant yeast-derived hepatitis B vaccine manufactured by Instituto Butantan was administered in two groups of adult volunteers (I, II) following two different schedules of immunization. In the first trial (10 mg doses and 0, 1, 3 months vaccination schedule) 106 individuals completed the full immunization program. The results of seroconversion by age group varied from 70 to 100% and the GMT from 46.5 to 124.9 mIU mL-1. In the second trial with 68 individuals (for dosage comparison and 0, 1, 6 months vaccination schedule) indicated that the vaccine formulated in 20 mg was more effective than in 10 mg. The adverse reactions observed in the vaccinees were less frequent than the ones previously found since the introduction of similar vaccines.

Three year seroepidemiological study of varicella-zoster virus in São Paulo, Brazil

A serosurvey of varicella has been carried out in children attending the public school network of São Paulo city, Brazil, from 1992 to 1994. This study was performed in order to establish the age related prevalence of antibodies against varicella-zoster virus (VZV) and its age specific transmission dynamics pattern in these children. Among 2500 schools in the city of São Paulo public network, 304 were randomly selected; 7 children of a given age (ranging from 1 to 15 years) were randomly selected in each school, and blood samples were obtained by fingerprick into filter paper. Blood eluates were analyzed for the presence of antibodies to VZV by ELISA. Proportion of seropositivity were calculated for each age group. Samples consisted of 1768 individuals in 1992, 1758 in 1993, and 1817 in 1994, resulting in 5343 eluates. A high proportion of seropositive children from 1 to 3 years of age was observed, ascending until 10 years of age and reaching a plateau around 90% afterwards. VZV transmission in this community was similar along the three years of the study. In children attending public schools in the city of São Paulo, contact with VZV occurs in early childhood. If immunization against VZV is considered it should be introduced as soon as possible.

Significance of isolated hepatitis B core antibody in blood donors from São Paulo

The clinical significance of isolated anti-HBc is still a challenge. To elucidate the real importance of this finding in our blood donors, an investigation algorithm was tested. One hundred and twelve isolated anti-HBc seropositive blood donors underwent clinical evaluation and retesting of HBV markers. Those who presented repeatedly reactive isolated anti-HBc, received a single dose of hepatitis B recombinant vaccine to verify anti-HBs early response. A HBV-DNA determination by PCR was done for those who did not test positive to anti-HBs after vaccine. The level of anti-HBc was recorded as a ratio of the sample-to-cut-off values (S:C ratio) in 57 candidates at donation. Comparing true and false-positive anti-HBc results, the different S:C ratios of them were statistically significant and when less than 2, implying in a false-positive result probability over 80%. A high percent of false-positive results (16.07%) was verified after anti-HBc retesting. HBV immunity was characterized in 49.11%, either by anti-HBs detection in retesting (15.18%), or after a single dose HBV vaccination (33.93%). HBV-DNA was negative in all tested donors. In conclusion, this algorithm was useful to clarify the meaning of isolated anti-HBc in most of our blood donors.

Aseptic meningitis in a large MMR vaccine campaign (590,609 people) in Curitiba, Paraná, Brazil, 1998

The aseptic meningitis after Measles-Mumps-Rubella vaccine (MMR) is a well recognized complication, and different incidences have been observed in several studies. We retrospectively analyzed forty cases of aseptic meningitis, during a large public immunization campaign (1998) in Curitiba, Southern Brazil (590,609 people), admitted in our Service. The vaccine utilized was Leningrad-3-Zagreb mumps strain, Edmonston-Zagreb measles strain, and RA 27#3 rubella strain. In all county, a total number of 87 cases were reported, resulting in a incidence of 1.7 cases per 10,000 given doses . The mean age was 23.7 ± 12.8 years. The female:male ratio was 1.35:1. Severe headache with meningismus (92.5%), fever (87.5%), nausea/vomiting (82.5%) were the most common clinical findings. Three cases (7.5%) developed mild mumps. All patients underwent cerebrospinal fluid (CSF) tap with the following findings: mononuclear pleocytosis from 100 to 500 cells/mm³ in 17 cases (42.5%; 257.5 ± 260.6 cells/mm³); increased protein 28 cases (67.5%; 92.1 ± 76.9 mg/dL); glucose was normal in all cases (56.8 ± 11.2 mg/dL) except in 4 (10%) cases, which presented less than 44 mg/dL. All serological tests (latex to bacterial meningitis, Cryptococcus, cysticercosis, VDRL) and bacteriological cultures were negative. Virus identification were also negative in 8 samples. None of the patients had neurological deficits or related symptoms after one year of onset. We believe the benefit of vaccination clearly outweights the incidence of benign vaccine-associated meningitis.

Outbreak of influenza type A (H1N1) in Iporanga, São Paulo State, Brazil

From June to July 1999 an outbreak of acute respiratory illness occurred in the town of Iporanga. Out of a total of 4,837 inhabitants, 324 cases were notified to the Regional Surveillance Service. Influenza virus was isolated from 57.1% of the collected samples and 100% seroconversion to influenza A (H1N1) was obtained in 20 paired sera tested. The isolates were related to the A/Bayern/07/95 strain (H1N1). The percentages of cases notified during the outbreak were 28.4%, 29.0%, 20.7%, 6.2% and 15.7% in the age groups of 0-4, 5-9, 10-14, 15-19 and older than 20 years, respectively. The highest proportion of positives was observed among children younger than 14 years and no cases were notified in people older than 65 years, none of whom had been recently vaccinated against influenza. These findings suggest a significant vaccine protection against A/Bayern/7/95, the H1 component included in the 1997-98 influenza vaccine for elderly people. This viral strain is antigenically and genetically related to A/Beijing/262/95, the H1 component of the 1999 vaccine. Vaccines containing A/Beijing/262/95 (H1N1) stimulated post-immunization hemagglutination inhibition antibodies equivalent in frequency and titre to both A/Beijing/262/95-like and A/Bayern/7/95-like viruses. Thus, this investigation demonstrates the effectiveness of vaccination against influenza virus in the elderly.