Epidemiology and dynamics of a newly emergent poxvirus infection in wild birds

In 2007 the first cases of a new form of infectious disease - a kind of pox - were reported from common birds in the UK. While pox is found in many birds, this usually occurs in low frequency and often with rather minor effects. The new form of pox occurs at higher frequency, and results in large infected lesions which have been found to cause death in wild birds, but otherwise very little is known about how the disease is transmitted and what effects it has on birds. This new form of pox seems to infect tits, in particular the great tit, at high frequency. In May 2010, this new disease appeared in a long-term study population of the great tit near Oxford, and has increased in frequency to infect almost 10% of great tits by November 2010. It is rare to study the emergence of a novel disease from the first cases, and this research aims both to understand the effect of this disease on birds, but also to study the factors determining its spread through two adjacent populations of tits, as well as more broadly through the UK. In order to do so we will:
(1) Catch birds repeatedly to study rates of infection and the progression of the disease in infected birds;
(2) Integrate information from captures with long-term study data to understand factors predisposing birds to disease;
(3) Collate information from reports from the public concerning the distribution and spread of this disease;
(4) Use post-mortem examination and molecular genetic tools to identify the pox virus responsible for these infections;
(5) Issue requests to the public to collect further data on the spread of this disease in 2011.

Infectious diseases can represent serious threats to wildlife; our aim with this research is both to assess the threat that this new disease poses to common UK garden birds, as well as to develop an understanding of the way in which it spreads through populations. Such knowledge is vital if we were to design interventions at a later stage.

The main impacts of this project will be a deeper understanding of the infection dynamics of a novel pox virus infection in wild birds, and in depth assessment of the effects this infection has on individual survival and reproductive output in common UK bird species. The results will be of considerable interest to the public, many of whom are concerned and alarmed when they see affected birds with grotesque lesions, as occurs in this disease.

At present it is too early to know whether this form of avian pox may have implications for the health of the populations that it infects, but if this is the case, the work carried out here will prove invaluable in determining the life-history stages at which these impacts are felt, and also may indicate possible routes of transmission. Hence, the results of this project may be of considerable benefit to ornithologists, conservation biologists and government who may need to understand the population impacts of this novel infection.