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?

Abstract

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 respectively, in 89.5% (374/418) and 10.5% (44/418) IA and IB in 93.3% (28/30) Hepatitis A virus (HAV) is a hepatotropic virus and a member of the Hepatovirus genus within the Picornaviridae family (Minor 1991). The virus is responsible for the majority of the acute hepatitis cases in Brazil (Gaspar et al. 1996), and infection symptoms are age-related. Among HAV-infected individuals, children under 6 years old are typically asymptomatic, whereas older children and adults develop jaundice or present dark urine. The prevalence of HAV infection is closely correlated with the level of environmental sanitation and with prevailing socioeconomic and hygiene conditions. The incidence of HAV is higher in developing countries, although the pattern of HAV endemicity in several of these countries has dropped from high to intermediary due to improvements in sanitation conditions in recent decades (Tapia-Conyer et al. 1999, Tanaka 2000. As a consequence, increasing proportions of those populations have had no contact with HAV and are therefore more susceptible to infection. In Brazil, hepatitis A is still considered an endemic disease, although data collected in the state of Rio de Janeiro indicate that a shift in the hepatitis A epidemiological pattern has taken place (Santos et al. 2002, Villar et al. 2002. 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 subgenotypesThe virus is usually transmitted via the fecal-oral route, either through person-to-person contact or through in- (Gehlbach et al. 1973, Williams et al. 1975. Results of some studies have suggested that HAV is transmitted mainly by children with either asymptomatic or subclinical infection. Lack of proper hygiene facilitates HAV transmission from such children to their relatives and friends, as well as to child care center staff members (Castelli et al. 1999, Poovorawan et al. 2005.The HAV strains have been classified into six genotypes (I to VI), based on nucleotide sequences of the VP1/2A junction region (Robertson et al. 1992. Prevalent human strains fall into genotypes I or III, each of which are divided into subtypes A and B. In Brazil, co-circulation of subgenotypes IA and IB have been found in Rio de Janeiro , Villar et al. 2004. Circulation of subgenotype IA has also been detected in other regions of Brazil (de Paula et al. 2004).Since it was first reported that HAV was able to propagate in cell culture (Provost et al. 1979), there have been many attempts to develop an HAV vaccine. In the United States and some other countries, safe and effective formalin-inactivated HAV vaccines against hepatitis A have ...

First report of a human autochthonous hepatitis E virus infection in Brazil

“…31 In urban areas such as the metropolitan area of Rio de Janeiro, outbreaks of hepatitis A have been described due to the exposure of susceptible population. [32][33][34][35] Nevertheless, epidemic HEV infections have not been yet found. The human HEV isolate (Brazil h1) from this study clustered with two swine strains (Brazil sw1 and Brazil sw2) also from Rio de Janeiro and a human Japanese isolate (E21-YKH00) from an sporadic acute case of genotype 3 and subtype 3b according to a classification proposed by Lu and Li.…”

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

“…Hepatitis A is transmitted by the faecal‐oral route, is responsible for the majority of viral hepatitis cases worldwide and is recognized as an important public health disease, especially in intermediate endemic regions [FitzSimons et al, 2010]. Due to public health improvements and better socioeconomic conditions, there has been a decline in HAV endemicity over the past few decades in Brazil [Tanaka, 2000; Villar et al, 2004; Morais et al, 2006; Vitral et al, 2006]. This decline decreases the incidence of natural immunization and creates a potential for massive outbreaks in closed communities such as schools and daycare centers [Villar et al, 2002; de Paula et al, 2002; Morais et al, 2006].…”

“…Due to public health improvements and better socioeconomic conditions, there has been a decline in HAV endemicity over the past few decades in Brazil [Tanaka, 2000; Villar et al, 2004; Morais et al, 2006; Vitral et al, 2006]. This decline decreases the incidence of natural immunization and creates a potential for massive outbreaks in closed communities such as schools and daycare centers [Villar et al, 2002; de Paula et al, 2002; Morais et al, 2006]. These institutions play an important role in the HAV chain of transmission due to the asymptomatic nature of the infection in children younger than 6 years old, which may lead to silent dissemination of the disease among susceptible adults [Desenclos and MacLafferty, 1993; Venczel et al, 2001; Poovorawan et al, 2005].…”

Hepatitis A virus subgenotypes dissemination during a community outbreak in a surrounding region of Rio de Janeiro

“…In the county of Belford Roxo, 26 HAV isolates had a 168 bp fragment of VP1/2A junction sequenced and most of them (61.5%) belonged to subgenotype IA that comprises over 80% of strains isolated worldwide (Robertson et al 1992 Morais et al 2006) and another one that occurred in a public school in the county of Paracambi (Rio de Janeiro) (Villar et al 2002). In the county of Belford Roxo, subgenotype IB was detected from January 2000 till November 2000 and all isolates shared the same homology suggesting a common source of infection.…”