Hepatitis a outbreak in a public school in Rio de Janeiro, Brazil

High prevalence of hepatitis A in indigenous population in north Brazil

Objectives

Little is known about hepatitis A virus (HAV) prevalence in indigenous communities. This study aims to evaluate the prevalence of HAV in indigenous community compared to urban population located at Western Amazon in Brazil.

Results

A total of 872 serum samples were obtained from 491 indigenous and 381 non indigenous individuals aging 0 to 90 years. Samples were tested for total and IgM anti-HAV and positive IgM samples were tested for HAV RNA. The overall prevalence of total anti-HAV was 87%, increased according age showing 100% of prevalence in those aging more than 30 years (p < 0.0001) and it was similar among indigenous and urban population. Total anti-HAV prevalence varied between tribes (p < 0.0001) and urban sites (p = 0.0014) and spatial distribution showed high prevalence in homes that received up to 100 dollars. IgM anti-HAV prevalence was 1.7% with predominance in males, those aging more than 41 years. No HAV RNA was detected. In conclusion, high overall anti-HAV prevalence was found in indigenous communities in North Brazil demonstrating the importance of universal vaccination in this group.

An immunoenzymatic assay for the diagnosis of hepatitis A utilising immunoglobulin Y

The detection of anti-hepatitis A virus (HAV) antibody levels by diagnostic kits in the convalescent period of disease generally use immunoglobulin G (IgG), which is expensive. An alternative to IgG is immunoglobulin Y (IgY), an immunoglobulin antibody encountered in birds and reptiles. The aim of this study was to develop a competitive immunoenzymatic assay to measure total anti-HAV antibody levels using anti-HAV IgY as the capture and conjugated immunoglobulins. For this purpose, anti-HAV IgY was conjugated to horseradish peroxidase (HRP) and the optimal dilution of HRP-conjugated antibodies was evaluated to establish the competitive immuneenzymatic assay. The results obtained from our "in-house" assay were plotted on a receiver operator curve, which showed a sensitivity of 95% and a specificity of 98.8%, demonstrating that a competitive anti-HAV IgY immunoenzymatic assay developed "in house" could be used as an alternative to commercial assays that utilise IgG.

[Hepatite A outbreak in an urban area of Luziânia, State of Goiás, Brazil, 2009]

INTRODUCTION

This paper describes the investigation to confirm an outbreak of hepatitis A, presents the case distribution by person, time and place, formulates a hypothesis concerning the mode of transmission and presents the recommended measures for prevention and control.

METHODS

A descriptive study of a case series and an environmental research were conducted.

RESULTS

An outbreak of hepatitis A was confirmed beginning in March 2009. Forty one (71%) individuals in the town received untreated water in their households. Thermotolerant coliform bacteria were detected in 20/58 (34%) water samples.

CONCLUSIONS

Consumption of contaminated water was the main hypothesis of virus transmission.

Exposure to multiple subgenotypes of hepatitis A virus during an outbreak using matched serum and saliva specimens

Matched serum and saliva samples were collected simultaneously from 124 subjects exposed during a hepatitis A virus (HAV) outbreak at a daycare center in Rio de Janeiro, Brazil. All samples were tested for IgM and total anti-HAV antibodies by enzyme immunoassay (EIA). HAV was detected by nested PCR in serum, saliva, and water samples employing primers for the VP1/2A region of the viral RNA; all positive products were then sequenced. The viral load of the matched samples was determined by real-time PCR using the TaqMan system. HAV-RNA was identified by nested PCR in 37.7% of the saliva samples, 29% of the serum samples, and one drinking water sample. The mean HAV viral load was similar in the serum and saliva specimens (10(3)  copies/ml). HAV genotypes IA and IB were detected in both specimen types, and the water sample isolate was classified as genotype IB, indicating the existence of more than one source of infection at the daycare center. In six infected patients, a different HAV subgenotype was found in their serum than in their saliva, and this unusual pattern of mixed HAV infection was investigated further by molecular cloning followed by nucleotide sequencing. All clones derived from the saliva samples belonged to subgenotype IB and shared 96.5-100% identity. However, clones derived from their corresponding serum sample belonged to subgenotype IA and shared 90.5-100% identity. This study showed the important role that non-invasive saliva samples can play in the molecular epidemiological analysis of a hepatitis A outbreak.

Prevalence of hepatitis A virus infection: the paradoxical example of isolated communities in the western Brazilian Amazon region

This study evaluated the prevalence of hepatitis A virus infection in the rural area of Lábrea, in the western Brazilian Amazon region. Communities and households were selected randomly. Serum samples were analyzed by means of the immunoenzymatic method for the presence of total antibodies against HAV. The study included 1,499 individuals. The prevalence of anti-HAV was 74.6% (95% CI 72.3-76.8). Univariate analysis showed associations with age (chi-square for linear trend = 496.003, p < 0.001), presence of outside toilet (p < 0.001), history of hepatitis (p < 0.001) and family history of hepatitis (p = 0.05). After adjusting for age, HAV infection also showed an association with the number of people in the family (p = 0.03). The overall prevalence rates were high, but not more than 60% of the children under the age of ten years had already been infected. Very high prevalence was detected only within older cohorts, thus paradoxically defining this as a region with intermediate endemicity, even under the conditions of poverty encountered.

Should Brazilian patients with chronic hepatitis C virus infection be vaccinated against hepatitis A virus?

BACKGROUND AND AIM

Hepatitis A virus (HAV) superinfection is associated with a high risk of liver failure and death in patients with hepatitis C virus (HCV) infection. The aim of this study was to investigate the presence of serological and molecular HAV markers in a population of HCV-infected patients in order to determine a cost-effective strategy to vaccinate against HAV.

METHODS

The presence of total and immunoglobulin (Ig)M anti-HAV antibodies was investigated in 399 patients (median age, 50 years; range, 4-81) referred to the Public Health Central Laboratory of Pernambuco State who tested positive for anti-HCV antibodies and HCV RNA. HAV RNA was investigated by reverse transcription-nested polymerase chain reaction in these patients.

RESULTS

Three hundred and eighty-four (96%) patients were positive for anti-HAV total and negative for IgM anti-HAV antibodies (immune patients). Three patients had IgM (and total) anti-HAV antibodies, showing an acute infection, and two of them had HAV RNA detected in serum samples. HAV RNA was also found in another patient in the absence of detectable anti-HAV antibodies. By nucleotide sequencing, it was demonstrated that the HAV isolates infecting these patients belonged to subgenotype 1B.

CONCLUSION

This study provides valuable new data on anti-HAV prevalence among HCV carriers in Brazil. In the present study, we found a high proportion of patients with anti-HAV positivity, indicating that anti-HAV testing of HCV-infected patients is a cost-effective strategy and should be carried out before vaccination against HAV in these patients, particularly in regions such as our geographical area with high total anti-HAV prevalence.

Changing epidemiology of hepatitis A in Brazil: reassessing immunization policy

Recent studies have shown that the prevalence of antibody to hepatitis A virus (HAV) is decreasing in several Latin American countries. Brazil is a very large and heterogeneous country, showing striking regional differences. With regard to sanitary facilities, 81.7% of the districts in the south-eastern region have sewage systems, compared with only 5.8% in the northern region. Results of sero-epidemiological studies and reported hepatitis A outbreaks indicate a change in the epidemiological pattern of hepatitis A in the country. Individuals, especially those under the age of 10, are mostly unprotected from HAV infection, regardless of their socioeconomic status. During 2000-2005, approximately 14 000-21 000 cases of hepatitis A were reported annually in Brazil, a rate of 7.5-11 cases per 100 000 population. Nationwide, hepatitis A mortality rates declined progressively from 1980 to 2002. As fatal cases constitute a small, but predictable, portion of all acute hepatitis A cases, which are in turn part of the total number of HAV infections, these data suggest that there has been a decline in HAV circulation in all Brazilian regions over the last two decades. Taken together these facts point out that the epidemiological pattern of hepatitis A is changing in Brazil. Besides improvements in sanitary conditions in the poorest Brazilian regions, the introduction of hepatitis A vaccination of young children could be a strategy for controlling HAV infection in the country.

Accuracy and repeatability of a micro plaque reduction neutralization test for vaccinia antibodies

The detection of neutralizing antibodies against vaccinia virus is a valuable tool for the investigation of previous smallpox vaccination. Compulsory smallpox vaccination ended in Brazil during the early 1970s, although the vaccine was available until the late 1970s. The threat of smallpox as a biological weapon has called the attention of public health authorities to the need for an evaluation of the immune status of the population. Based on our previous experience with a micro plaque reduction neutralization test (PRNT) for the evaluation of yellow fever immunity, a similar test was developed for the detection and quantification of vaccinia neutralizing antibodies. A cross-sectional study to test the repeatability and validity of plaque reduction neutralization test (PRNT) for vaccinia antibodies was performed in 182 subjects divided into two categories: subjects above 31 years old and the other > or = 35 years old. Cases were subjects considered to have been vaccinated with vaccinia virus if they declared vaccination history or evidenced vaccination marks. The assay is carried out in 96-well plates, provides results within 30 h, is easily performed, has good sensitivity (92.7%) and specificity (90.8), excellent repeatability (ICC 0.89 (0.88; 0.92)) and is thus suitable for use in mass screening of a population's antibody levels.

Hepatite A no Município do Rio de Janeiro, Brasil: padrão epidemiológico e associação das variáveis sócio-ambientais. Vinculando dados do SINAN aos do Censo Demográfico

Objetivamos discutir a vinculação do Sistema de Informações de Agravos de Notificação (SINAN) e do Censo Demográfico para conhecer o contexto sócio-ambiental da hepatite A, analisando a contribuição das variáveis ambientais e sócio-demográficas para ocorrência de casos notificados e confirmados da infecção. Também, com base nas informações individuais sobre os casos de hepatite A notificados e confirmados, obtidos no SINAN, discutimos o padrão de endemicidade no Município do Rio de Janeiro, Brasil. No estudo agregado, a unidade de análise foi o setor censitário e as informações do Censo 2000, associadas à localização dos 1.553 casos notificados e confirmados de hepatite A ocorridos na cidade entre 1999-2001. Observou-se um padrão epidemiológico entre alta e média endemicidades, indicando situação menos favorável do que a observada nos estudos soro-epidemiológicos. A média rank do número de domicílios com condições sócio-ambientais desfavoráveis foi maior nos setores censitários de sobre-risco para hepatite A (dois ou mais casos) com significância estatística pelo teste de Mann-Whitney. As variáveis sócio-demográficas mostraram ter maior influência do que as ambientais na ocorrência de casos: maior percentual de pobreza e de menores de cinco anos apresentou as maiores diferenças de médias rank.

Evaluation of methods used to concentrate and detect hepatitis A virus in water samples

Two adsorption-elution concentration methods, both involving negatively charged membranes, were evaluated in order to monitor hepatitis A virus (HAV) contamination in tap, river, mineral and coastal water samples: elution with urea-arginine phosphate buffer/reconcentration with magnesium chloride (method 1); and sodium hydroxide elution/reconcentration with a commercial concentrator (method 2). Nested (qualitative) reverse transcriptase PCR (RT-PCR) and real-time (quantitative) RT-PCR were used to detect and quantify HAV RNA in concentrated water samples. For concentrating HAV, method 1 was found to be the most suitable for tap water and method 2 most suitable for mineral water. HAV inoculated experimentally was detected in river water samples by both methods and in coastal water samples by neither method. The detection limits were 6 x 10(9) g equiv./ml for qualitative PCR and 60 g equiv./ml for quantitative PCR. In a field application study, HAV was detected in 20% of river and tap water samples but not in coastal or mineral water samples. River water samples contained subgenotype IA, and tap water samples contained subgenotype IB. It is concluded that, although influencing qualitative PCR, the concentration method does not affect quantitative PCR, which could therefore be used for all types of water samples. Both techniques are recommended for detecting HAV in environmental water samples.

Co-circulation of genotypes IA and IB of hepatitis A virus in Northeast Brazil

The Northeast region is the location of most cases of acute hepatitis A virus (HAV) in Brazil. In the present study, the genotypes of HAV strains from Pernambuco State, one of most populous states in the Northeast region, were characterized. Blood samples positive for anti-HAV IgM from 145 individuals (mean age = 29.1 years), collected during 2002 and 2003, were submitted to nested RT-PCR for amplification of the 5'non-translated region (5'NTR) and VP1/2A regions of the HAV genome. The VP1/2A and 5'NTR regions were amplified in 39 and 21% of the samples, respectively. Nucleotide sequencing was carried out in 46% of VP1/2A and in 53% of 5'NTR isolates. The identity in nucleotide sequence of the VP1/2A region ranged from 93.6 to 100.0%. Phylogenetic analysis of the VP1/2A sequences showed that 65% belong to sub-genotype IA and 35% to sub-genotype IB. Co-circulation of both sub-genotypes was observed in the two years studied. Distinct clusters of highly related sequences were observed in both sub-genotypes, suggesting endemic circulation of HAV strains in this area. In the 5'NTR isolates, 92.7-99.2% identity was observed and two isolates presented one deletion at position 413. Phylogenetic analysis showed that genotype IA strains cluster in the tree in the same way as genotype IB strains, but one IIIA isolate from Spain clusters with genotype IB strains. These results do not allow us to state that 5'NTR could be used to genotype HAV sequences. This is the first report of co-circulation of sub-genotypes IA and IB in this region, providing additional information about the molecular epidemiology of HAV strains in Brazil.

Early infection and asymptomatic spread of hepatitis A virus in a public child care center in Rio de Janeiro, Brazil: should attending children under two years of age be vaccinated?

A cross-sectional study was conducted in order to identify hepatitis A virus (HAV) serological markers in 418 individuals (mean age, 16.4 years; range, 1 month-80 years) at a public child care center in Rio de Janeiro, Brazil, as well as to analyze risk factors and determine circulating genotypes. Serum samples were tested using an enzyme immunoassay. Reverse transcription polymerase chain reaction (RT-PCR) was used to detect and characterize HAV RNA, and sequencing was performed. Anti-HAV antibodies and IgM anti-HAV antibodies were detected, respectively, in 89.5% (374/418) and 10.5% (44/418) of the individuals tested. Acute HAV infection in children was independently correlated with crawling (p < 0.05). In 56.8% (25/44) of the IgM anti-HAV-positive individuals and in 33.3% (5/15) of the IgM anti-HAV-negative individuals presenting clinical symptoms, HAV RNA was detected. Phylogenetic analysis revealed co-circulation of subgenotypes IA and IB in 93.3% (28/30) of the amplified samples. In present study, we verify that 79% (30/38) of children IgM anti-HAV-positive were asymptomatic. In child care centers, this asymptomatic spread is a more serious problem, promoting the infection of young children, who rarely show signs of infection. Therefore, vaccinating children below the age of two might prevent the asymptomatic spread of hepatitis A.

Prevalence of hepatitis A virus infection in Goiânia, Goiás, Brazil, by molecular and serological procedures, 1995-2002

In this study, a total of 865 serum samples were collected between 1995 and 2002 from individuals living in Goiânia, Central Brazil, and clinically suspected of hepatitis. After exclusion of 162 samples which were positive for hepatitis B virus or hepatitis C virus, 703 samples were tested for anti-hepatitis A virus (anti-HAV) IgM antibodies by enzyme immunoassay. In addition, 588 of these samples and 22 fecal samples were analyzed by reverse transcription-nested PCR for HAV RNA detection, with positivity indices of 13.1% (77/588) and 54.5% (12/22), respectively. A similar index of viral RNA detection in anti-HAV-IgM positive or negative samples was observed in serum samples. HAV infection is a public health problem worldwide and this study underscores the extent of HAV circulation in our region.

Epidemiological pattern and mortality rates for hepatitis A in Brazil, 1980-2002: a review

The prevalence of hepatitis A virus (HAV) infection is high in developing countries, in which low standards of sanitation promote the transmission of the virus. In Latin America, which is considered an area of high HAV endemicity, most HAV-positive individuals are infected in early childhood However recent studies have shown that prevalence rates are decreasing. Herein, we review the data on HAV prevalence and outbreaks available in scientific databases. We also use official government data in order to evaluate mortality rates in Brazil over the last two decades. Studies conducted in the northernmost regions of Brazil have indicated that, although improved hygiene has led to a reduction in childhood exposure to HAV, the greatest exposure still occurs early in life. In the Southeastern region, the persistence of circulating HAV has generated outbreaks among individuals of low socioeconomic status, despite adequate sanitation. Nationwide, hepatitis A mortality rates declined progressively from 1980 to 2002. During that period, mortality rates in the Northern region consistently exceeded the mean national rate and those for other regions. Excluding the North, the rates in all regions were comparable. Nevertheless, the trend toward decline observed in the South was paralleled by a similar trend in the North.

Epidemiology of hepatitis A and E virus infection in Brazil

This review has the objective to discuss the epidemiological aspects of the enterically transmitted hepatitis A and E in Brazil. The prevalence of hepatitis A varies greatly in different Brazilian regions, from 56% in South and Southeast to 93% in North region (Manaus, Amazon). Such differences are also found in different socioeconomic levels among age groups. A significantly higher prevalence was seen in the low socioeconomic group between 1-30 years. This difference is most striking in the first 10 years of age (23.5% vs 60.0%, high/middle vs low, respectively). Despite the improvements in sanitary conditions, hepatitis A is still endemic and outbreaks may occur. As an increasing proportion of the population is becoming susceptible to hepatitis A virus infection and as adult individuals may present more severe forms of the disease, the authors conclude that the implement of hepatitis A vaccination should be considered. Some Brazilian data have shown that the genotype found in our country were IA and IB. Isolates from this study were closely related genetically (or even identical) to isolates originating in other South American countries and overseas, providing firm evidence for epidemiological links between persons who travel to endemic areas. In spite of favorable environmental conditions, outbreaks of hepatitis E have never been reported in Brazil. Nevertheless, reports have demonstrated the evidence of anti-hepatitis E virus antibodies in some Brazilian regions. The seroprevalence of IgG anti-hepatitis E virus among normal populations shows positivities of 6.1% in gold-miners, 3.3% in general population, 2.0-7.5% in blood donors, 1.0% in pregnant women, and 4.5% in children, with no differences among regions. In populations at risk the prevalence of anti-hepatits E virus varies greatly. Among patients with acute non-A, non-B, non-C hepatitis 2.1% was detected in the Southeast to 29% in the Northeast, in 10.6% of acute non-A, non-B, non-C hepatitis relatives in the Amazon basin, in 12% of acute sporadic non-A non-B hepatitis patients in the Northeast, a co-infection with acute hepatitis A in 25 to 38% in the Northeast, in 14 to 18% among prostitutes and women considered at risk for human immunodeficiency virus in the Southeast, and in 12% of the intravenous drug users in the Southeast.

Prevalence of anti-hepatits A antibodies in children of different socioeconomic conditions in Vila Velha, ES

This report describes the prevalence of anti-HAV antibodies in children from elementary school in the Municipality of Vila Velha, ES, Brazil. Anti-HAV antibodies were investigated by ELISA method in the serum of 606 children (four to fourteen years old) from three elementary schools, located in neighborhoods with varying household monthly income levels: São José School, 200 children, household income higher than US$700; São Torquato School, 273 children, US$200 to 300; and Cobi School, 133 children, less than US$200. From each children data on age, gender, skin color, sanitary conditions, frequency of contact with sea or river water and family history of hepatitis were recorded. Anti-HAV antibodies were present in 38.6% of all children, 9% in São José School, 49.1% in São Torquato School and 61.7% in Cobi School. Logistic regression analysis demonstrated a positive correlation of positive anti-HAV test with age, non white color of the skin, absence of sewage treatment and domestic water filter, and a past history of hepatitis. The prevalence of anti-HAV antibodies in school children in Vila Velha, ES, was lower than that observed in the same age group in North and Northeast Brazil and was significantly higher in children from families with low socioeconomic status. In addition the results indicate a changing epidemiologic pattern of hepatitis A in our country, with an increasing number of children and adolescents with high risk for HAV infection, mainly in high socioeconomic class. A consideration must be given to the feasibility of vaccination programs for children and adolescents in our country.

Genetic analysis of hepatitis A virus isolates from Brazil

A limited number of hepatitis A virus (HAV) isolates from South America have been characterised at the genomic level. IgM anti-HAV positive serum samples collected from patients with hepatitis A living in the five geographical regions of Brazil (North, Northeast, Central, South, and Southeast) were used to obtain HAV isolates and determine their genetic relatedness. Of the 232 case isolates, sequence data were obtained from the VP1/2A junction region of the HAV genome. All isolates were classified in genotype I; 231 belonged to subgenotype IA, and one to subgenotype IB. HAV isolates from four States formed distinct clusters of highly related sequences. However, isolates from other states did not cluster and the sequences from those states were intermingled with sequences found in the other states. The amino acid sequences of all but two isolates showed a Leu --> Ile substitution at position 42 in the 2A protein. This substitution appeared to be a characteristic geographic fingerprint of HAV sequences within Brazil.

Genetic variability of hepatitis A virus isolates in Rio de Janeiro: implications for the vaccination of school children

The epidemiology of hepatitis A virus (HAV) infection is shifting from high to intermediate endemicity in Brazil, resulting in increased numbers of susceptible individuals and a greater potential for the emergence of outbreaks. Universal vaccination against HAV has been recommended for children, but updated sero-epidemiological data are necessary to analyze the level of natural immunity and to identify candidates for preventive measures. In addition, more molecular studies are necessary to characterize the genotypes involved in HAV infections and outbreaks. Sera from 299 school children (5-15 years old) and 25 school staff members, collected during an outbreak of HAV at a rural public school in June 2000, were tested for IgM and total anti-HAV antibodies (ELISA). Viral RNA was amplified by RT-PCR from anti-HAV IgM-positive sera and from 19 fecal samples. Direct nucleotide sequencing of the VP1/2A region was carried out on 18 PCR-positive samples. Acute HAV infection was detected by anti-HAV IgM in 93/299 children and in 3/25 adult staff members. The prevalence of total anti-HAV antibodies in IgM-negative children under 5 years of age was only 10.5%. HAV-RNA was detected in 46% IgM-positive serum samples and in 16% stool samples. Sequence analysis showed that half the isolates belonged to subgenotype IA and the other half to IB. On the basis of these data, mass vaccination against HAV is recommended without prevaccination screening, especially for children before they enter school, since nearly 90% of the children under 5 years were susceptible. Molecular characterization indicated the endemic circulation of specific HAV strains belonging to subgenotypes IA and IB.

Mixed infection of a child care provider with hepatitis A virus isolates from subgenotypes IA and IB revealed by heteroduplex mobility assay

Phylogenetic analysis based on a 168 base segment encompassing the putative VP1/2A junction of the hepatitis A virus (HAV) genome has enabled the classification of HAV isolates into seven genotypes (I-VII). Genotype I, which includes the vast majority of the human HAV isolates, has been divided further into subgenotypes IA and IB. An heteroduplex mobility assay was designed with amplification products from the VP1/2A junction region, and used as a genotyping method able to discriminate HAV isolates belonging to IA, IB and non-I genotypes. The method was used to successfully genotype 48 samples (16 IA and 32 IB). However, one HAV RNA positive serum sample (AUX-23), collected from a 15 year old female employed at a child care center located in Rio de Janeiro, Brazil, showed an unusual pattern. PCR products from sample AUX-23 gave rise to heteroduplex bands when mixed with IA products as well as with IB products, suggesting the presence of HAV isolates from both subgenotypes in the serum. PCR products from sample AUX-23 were then cloned and 20 clones were analyzed by heteroduplex mobility assay. Eleven were subgenotype IA and 9 were IB. Three clones of each subgenotype were then sequenced to confirm the results. These data constitute the first report of mixed infection of a single individual with different HAV isolates.