Climatic factors associated with the infection of herds of cattle with bluetongue viruses.
The incidence of bluetongue virus infection of 15 cattle herds in Queensland, Australia, was determined by a serum neutralization test. The maximum temperature (degree C), minimum temperature (degree C) and rainfall (mm) data were obtained from the meteorological recording stations closest to each herd. Using unweighted least-squares regression analysis, the best statistical model explaining the most variability in the herd incidence rate included the ratio between the maximum and minimum temperature recorded at both 1 month and 6 months preceding seroconversion, and rainfall recorded at both 2 months and 6 months preceding seroconversion. More than 90% of the variability in the incidence of bluetongue virus infection in the herds was explained by the model, a considerable improvement on previous models that used prevalence data. The prospective nature of the study also supports a strong causal relationship between climatic factors and the occurrence of infection in cattle herds.
Ward
M P
MP
Queensland Department of Primary Industries, Toowoomba, Australia.
D000704:Analysis of Variance; D000818:Animals; D001819:Bluetongue / Q000453:epidemiology*; D001820:Bluetongue virus / Q000302:isolation & purification; D002417:Cattle; D002980:Climate; D015994:Incidence; D016018:Least-Squares Analysis; D011793:Queensland / Q000453:epidemiology; D011891:Rain; D013696:Temperature