Estimating Dynamic Risk Factors for Pathogen Transmission Using Community-Level Bird Census Data at the Wildlife/Domestic Interface

Abstract

ABSTRACT. The ecology of host species is crucial for understanding the mechanisms of pathogen transmission and spread in complex multi-host systems. In this article, we use detailed observations of the host community to develop and apply a new approach to mapping temporal variation in risk for avian influenza. Working in an extensive wetland system near Harare, Zimbabwe, we use the overlap in space and time of highly variable bird communities, combined with ecological risk factors, to assess the risk of Avian Influenza viruses (AIV) maintenance and transmission between bird populations. The estimated introduction and maintenance risks associated with waterfowl populations at a given time are then multiplied by the level of interactions with neighboring domestic production systems during the same period. This approach is used to develop hypotheses for the dynamics of the introduction and circulation of AIV strains in waterfowl populations and as a way of understanding the potential role of "bridge" species at the wild/ domestic interface. The novel approach presented here offers a potentially useful way to explore AIV risk, identify which wild bird species may be acting as reservoirs or vectors of pathogens at a local scale, and improve local surveillance.

Bridge hosts for avian influenza viruses at the wildlife/domestic interface: An eco-epidemiological framework implemented in southern Africa

“…If no seasonal or inter-annual trends were observed at the IS level, at the (dominant) species level, wild bird ecology induces periodic trends in potential contacts. The low variability of species richness across season and years supports the hypothesis that domestic compartment "artificially" attract wild bird species, as the species richness varied on the lake shores in a previous study (Caron et al, 2010).…”

“…Bird counts in each counting site were implemented as described previously (Caron et al, 2010;Cumming et al, 2011b). Focal counts were undertaken to estimate species diversity and the abundance of waterfowl and domestic communities.…”

“…Four 30-minute counts, each at a different time of the day (06:00-09:00; 09:00-12:00; 12:00-15:00; and 15:00-18:00) were carried out in a random sequence at each site for each recording session. Ten minutes after arrival on the counting site, counts of thirty minutes This first protocol will be referred as "the intensive protocol" (part of this data has already been presented in Caron et al (2010). Seven waterfowl counting sites, 2 backyard poultry and 2 intensive poultry counting sites from the intensive protocol were counted also from September 2009 to Sessions in waterfowl compartments were paired with the nearest sessions in domestic compartment in time to compare wild bird communities between compartments.…”

Factors influencing long-term and seasonal waterbird abundance and composition at two adjacent lakes in Zimbabwe

“…The risk of avian influenza is likely to be higher during the seasons when overall abundance is high (July and October), during drought years and at Lake Manyame rather than Lake Chivero because of the higher numbers of wildfowl at Lake Manyame. These results are in agreement with recent studies (Caron et al 2010). …”

Rôle des oiseaux sauvages dans la transmission et la dispersion des virus de l’influenza aviaire : apport de l’éco-épidémiologie dans les écosystèmes afro-tropicaux

“…Une étude de terrain a été réalisée pour identifier les espèces relais potentiel des VIA au Zimbabwe, dans un écosystème où cohabitent une large variété d'oiseaux sauvages et différents systèmes d'élevage, intensifs et extensifs (Caron et al, 2010(Caron et al, , 2014. La réalisation de comptages d'oiseaux sur des sites épidémiologiques clés (zones humides, périphérie de villages, élevages intensifs) a permis d'identifier des espèces d'oiseaux capables de créer un lien infectieux entre populations sauvages et domestiques et de caractériser les saisons les plus à risque de transmission de VIA.…”