The role of water in human picornavirus transmission

Abstract

The overall research question of the work presented in this thesis was whether the presence of human picornaviruses in the aquatic environment poses a problem to public health. A multidisciplinary approach was used to determine the extent to which human picornaviruses circulate in the general population, and if and to which extent people are exposed to which human picornaviruses in surface waters, closing their aquatic cycle. This thesis offered new insights in the prevalence of several human picornaviruses in the Dutch environment indicating circulation in the sampled human population by environmental surveillance. Furthermore, the sensitivity of the environmental surveillance was estimated, and the usefulness, of culture and PCR data, with respect to water treatment processes and exposure probabilities, was evaluated. The omniprevalence of the diverse family of human picornaviruses (enteroviruses, parechoviruses, hepatitis A viruses, Aichi viruses, Saffold viruses and cosaviruses) in sewage and surface water was demonstrated, as well as virus evolution dynamics for several of the detected picornaviruses. Exposure to such waters e.g. through water recreation of children may lead to a public health risk although risk factors could not be identified. To conclude, although the multidisciplinary approach presented in this thesis yielded a lot of information on a role of water in the transmission of picornaviruses, we could not generally state that the presence of picornaviruses in water used for drinking and recreational purposes is considered to constitute a potential public health risk. Except when vulnerable individuals, such as young children, the elderly, pregnant women and immune-compromised individuals are exposed to these contaminated waters. Further studies should address the possible picornavirus transmission routes, including water, to be able to protect the public health and to implement possible intervention measures.