Morbidity, Mortality, and Immunity
RHD is extremely hard to locate in the wild since about 75% of rabbits with RHD will die in their burrows underground. Due to this difficulty, the morbidity and mortality estimates for RHD have a broad range. The morbidity rate ranges from 30% to 100% and the mortality rate from 40% to 100%; however, the typical mortality rate is usually around 90%.
In the wild, outbreaks in rabbits vary depending on the season, breeding cycles and geographical location. Some areas will see a high morbidity and mortality among its rabbit populations followed by calmer periods.
Maternal antibodies such as immunoglobulin G (IgG), which are readily transmitted to the young across the placenta, may explain why very young rabbits are resistant to RHD. Some scientists also believe that the immature immune system of a young rabbit cannot produce the number of chemicals needed to initiate clotting in order to kill. Rabbits may develop immunity against other strains of the RHD virus, while others may endure persistent infections. The immunity does not survive through the next generation, leaving open the possibility of further outbreaks in the population.
A population of rabbits on the San Juan Islands, Washington, USA appears to be immune to RHD. The cottontail rabbit and jackrabbit are not affected by the disease; nor are humans or other mammals.
Read more about this topic: Rabbit Haemorrhagic Disease
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