The intensity of transmission of hepatitis A and heterogeneities in socio-environmental risk factors in Rio de Janeiro, Brazil.
The objective of this work was to assess the intensity of transmission of hepatitis A in Rio de Janeiro, Brazil. We also used the estimation of the parameters of a deterministic model to study the effects of risk factors. Age-specific seroprevalence of antibodies against hepatitis A virus (HAV) was obtained from a survey screening in a city of the metropolitan area of Rio de Janeiro, in 1997. From the seroprevalence data, we estimated the age-dependent force of infection (lambda) and the average age of first infection (A), using a deterministic model. To evaluate the influence of the environmental risk factors, we estimated the same parameters stratifying the sample for the selected socio-environmental risk factors: the number of years of schooling of the female responsible for the house, crowding within the bedroom, number of water taps and fittings, and the presence of sewage in front of the house. For the whole sample, the maximum force of infection estimated was 0.12/year and the average age of infection was 10.1 years. This last parameter decreased as the number of persons per bedroom increased, and also when the number of water taps and the number of years of schooling of the woman responsible for the house decreased. The proposed environmental interventions may lead to a decrease in the intensity of transmission of HAV and an increase in the average age of first infection in the next few years. This may have public health implications, since hepatitis A is more severe in adults. In this context, specific vaccination programmes may be necessary, as in developed countries.
de Almeida
Liz Maria
LM
Núcleo de Estudos de Saúde Coletiva, Universidade Federal do Rio de Janeiro, Av. Brig. Trompowski, s/n, HUCFF, 5o andar/Ala Sul, sala 25, Ilha do Fundão, 21941-590 Rio de Janeiro, RJ, Brazil.
Amaku
Marcos
M
Azevedo
Raymundo Soares
RS
Cairncross
Sandy
S
Massad
Eduardo
E
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001938:Brazil / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D003441:Crowding; D005260:Female; D006506:Hepatitis A / Q000453:epidemiology / Q000635:transmission*; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D012959:Socioeconomic Factors