Further investigation of wild birds and H5N1 transmission within the Central Asian Flyway will increase our understanding of how wild birds may contribute to virus circulation and the unique pattern of outbreaks in this remote region.
Qualitatively, the model predicts a similar pattern of outbreaks (Figure 1) to that observed in northern Europe in 2006 and 2007 (i.e. in the absence of vaccination), with small numbers of affected holdings in the first year, followed by large numbers in the second year [9].
The short incubation period of two hours to five days, enhances the potentially explosive pattern of outbreaks.
Study of the spatiotemporal pattern of outbreaks is important in the prevention and control of epidemics over large regions [ 53].
Little is known about natural reservoirs of tularemia, F. tularensis transmission mechanisms to humans, and factors influencing the often irregular pattern of outbreaks.
However, the pattern of outbreaks in southern Europe suggests that viremic migratory birds may also contribute to movement of the virus.
The seasonal pattern of outbreaks in which all specimens were negative in this study suggests that many may also have been caused by noroviruses.
Also, in Gambia a regular pattern of outbreaks during 6 consecutive annual seasons was disrupted by 2 years of irregular outbreaks, followed by another 2 years of regular seasonal outbreaks [ 24].
Although we were able to detect influenza virus among poultry continuously during surveillance, we did not establish a clear seasonal pattern of outbreaks, an indicator of continuous evolution of subtype H5N1 viruses endemic to Egypt.
In contrast to the historically observed pattern of outbreaks in Europe and Africa between the 50s and the 90s, in which epidemics were followed by years of inactivity, WNV continued to spread in the U.S. following its introduction.
