Changing epidemiology of hepatitis A in Brazil: reassessing immunization policy

Abstract

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.

Seroprevalence of hepatitis A in children and adolescents

“…Essas diferenças regionais podem ser exemplificadas ao analisar-se a disponibilidade de água potável e de sistema de esgoto para a população. Considerando o país como um todo, a maioria dos domicílios tem acesso a esses serviços, entretanto, analisando regiões separadamente, o sistema de esgoto está presente em 81,7% dos distritos da Região Sudeste e em somente 5,8% da Região Norte do país 9,13 .…”

Hepatitis A seroprevalence in public school children in Campos dos Goytacazes, Rio de Janeiro State, Brazil, prior to the introduction of the hepatitis A universal childhood vaccination

“…In Brazil, seroprevalence studies conducted recently mainly in urban areas, showed a consistent decrease of the incidence rates in childhood 4,5,6,7,8,9,10 . Decrease in HAV circulation 8,9,11,12 as well as a progressive decline in fatal cases related to HAV infection in all Brazilian regions 8 have also begun to be noticed.…”

“…In fact, the prevalence of HAV infection could even be used as an index of the level of development of a given country 12 . However, it has been shown that the introduction of sanitary improvements is a major factor in changing the prevalence of HAV infection, even when the socioeconomic level of a given population remains low 9,10 . In the absence of public sanitary facilities, simplistic mechanisms of water and sewage disposal, such as artesian wells and septic cesspools are efficient for minimizing the chance of HAV infection 10 .…”

“…Decrease in HAV circulation 8,9,11,12 as well as a progressive decline in fatal cases related to HAV infection in all Brazilian regions 8 have also begun to be noticed. According to the Brazilian Surveillance System, there is an apparent downward trend in the number of hepatitis A cases reported along the years.…”

Shifting susceptibility to hepatitis A among children and adolescents over the past decade

“…Fatores tais como mudanças na epidemiologia global da hepatite viral A, refletindo o crescimento de uma população suscetível 8,9 , e a disponibilidade de vacinas eficazes 1,2 têm renovado o interesse nessa doença, ressaltando a necessidade de um conhecimento mais preciso da nova realidade para definir as estratégias de prevenção 10,11 . No Brasil, estudos sorológicos têm demonstrado que a endemicidade da hepatite A está mudando na maioria das regiões, com taxas significativamente menores de anticorpo anti-VHA (anti-VHA) entre as crianças e os adolescentes [12][13][14][15] , especialmente de classe socioeconômica mais favorecida 12,14,15 .…”