Molecular epidemiology of hepatitis A in Noord-Brabant, The Netherlands

Previous studies on the molecular epidemiology of hepatitis A virus (HAV) in Amsterdam, The Netherlands, show that subgenotype 1A is mainly seen among homosexual men practising anonymous oral-anal sex in saunas and darkrooms, while subgenotype 1B is usually detected among children originating from Morocco, and subgenotype 3A is mostly found among travellers to Pakistan.

We studied the genotype distribution in a more rural area of The Netherlands, Noord-Brabant, and compared it with Amsterdam.

We collected blood and feces samples from 34 HAV IgM(+) individuals who were reported from August 2001-March 2003 at the Municipal Health Service (MHS) Heart for Brabant (Brabant). We also collected feces samples from nine household contacts of whom the HAV IgM status was not known. HAV RNA was isolated and subsequently amplified by reverse transcriptase polymerase chain reaction (RT-PCR) at the VP1-P2a and the VP3-VP1 region, sequenced and analysed.

In most cases, relations between risk groups and HAV subgenotypes in Noord-Brabant were similar to those in Amsterdam. Next to genotypes 1 and 3 we also detected a genotype 2/7 strain in a Noord-Brabant case. Also, in contrast to the Amsterdam study, sporadic transmission occurred among various risk groups. Children involved in a school-related outbreak were infected with strains identical to one that was previously isolated from a man who has sex with men (MSM). Also, Dutch patients having no epidemiological link with Turkish or Moroccan children harboured strains imported from high-endemic countries. Furthermore, we report a special case in which HAV may be causally involved in meningitis. The results of this study show that the molecular epidemiology of HAV in The Netherlands can be more complicated than previously anticipated and that HAV phylogenetic studies can provide important information for the design of appropriate public health measures.