How did myxomatosis affect rabbit populations in Australia?

Myxomatosis is a highly fatal viral disease caused by the myxoma virus, which was introduced to Australia in the early 1950s as a biological control measure against the invasive European rabbit population.123

The impact of the virus on rabbit populations occurred in two distinct phases:

• Initial Impact: Upon its introduction, the virus was extremely virulent, killing approximately 99 percent of the infected rabbit population within two weeks.23
• Coevolutionary Shift: Over time, the interaction between the virus and the rabbits evolved. As rabbit numbers plummeted, natural selection favored mutant strains of the virus that were less lethal, allowing the host to survive longer and thereby increasing the virus's opportunity to spread to new hosts. Simultaneously, the rabbit population developed a degree of immunity.32

Consequently, while the virus remains a significant factor, subsequent waves of infection have proven less effective than the initial outbreak, and most infected rabbits now survive for several weeks rather than dying almost immediately. Ongoing efforts to manage the population continue to rely on a combination of biological controls, poisoning, and physical destruction of warrens.23