Avian influenza A H5N1 infections in Bali province, Indonesia: a behavioral, virological and seroepidemiological study

Abstract

Background Bali Province was affected by avian influenza H5N1 outbreaks in birds in October 2003. Despite ongoing circulation of the virus, no human infection had been identified by December 2005. Objectives To assess behavioral patterns associated with poultry rearing in Bali, and to identify potential risk factors for H5N1 infection in humans and in household chickens, ducks and pigs. Methods A behavioral, virological and seroepidemiologic survey in 38 villages and three live bird markets was completed in December 2005. A multi‐stage cluster design was used to select 291 households with 841 participants from all nine districts in Bali. Specimens were collected from participants as well as a maximum of three pigs, chickens and ducks from each household. Eighty‐seven market vendors participated, where specimens were collected from participants as well as chickens and ducks. Results Twenty out of the 38 villages sampled had H5N1 outbreaks. Despite exposure to H5N1 outbreaks, none of the participants from villages or markets were seropositive for H5N1. None of the pigs tested were positive for H5N1. Virus isolation rate in ducks and chicken in markets was higher than in households. Transport of poultry in or out of villages was a risk factor for outbreaks in household chickens and ducks. Conclusions The study highlighted that the market chain and associated behaviors may play a role in maintaining the virus in household flocks. The study adds evidence that transmission of H5N1 to humans remains a rare event despite high level handling of both healthy and sick birds.

Landscape attributes driving avian influenza virus circulation in the Lake Alaotra region of Madagascar

“…In spite of these limitations, the present study made it possible to identify risk factors associated with exposure of poultry to AIV. The study found higher AIV seroprevalence in palmipeds (ducks and geese) than in chickens, which is consistent with findings by other serological surveys carried out in unvaccinated birds raised in small-scale farms of Indonesia (Santhia et al, 2009) or Vietnam (Henning et al, 2009;Desvaux et al, 2012). The reason why this should be so can be explained.…”

Highly Pathogenic Avian Influenza (H5N1): Pathways of Exposure at the Animal‐Human Interface, a Systematic Review

“…Three studies from Thailand, Cambodia and Indonesia of the seven studies evaluating seroprevalence in rural areas found no evidence of anti-H5 antibodies in their study populations despite frequent contact in households with poultry with probable H5N1 infection [24], [29], [30]. However, evidence of exposure to poultry resulting in asymptomatic human infection was found in 1 study in China, and 2 studies in Cambodia.…”

Emergence of a novel swine-origin influenza A virus (S-OIV) H1N1 virus in humans

“…Furthermore, avian viruses have been transiently detected in swine in many parts of the world, including H1N1, H9N2, H4N6 and H5N2 [13, 17, 22, 25–27] but it is not clear whether these viruses will establish long term transmission in pigs. While highly pathogenic H5N1 viruses have been occasionally detected in pigs [22, 28], experimental studies indicate that pig-to-pig transmission is limited [29, 30] and serological studies do not reveal widespread transmission of H5N1 viruses in pigs in areas where this virus remains endemic in poultry [29, 31]. …”