Ross River virus activity along the south coast of New South Wales.

This research investigated the presence of the Ross River virus, a mosquito-borne disease, in the south coast of New South Wales based on tests done on human and animal sera. It found that 7% of human sera, 25% of cow sera, and 65% of horse sera had antibodies to this virus.

Methodology

• The study worked with the sera of 468 blood donors and 63 domestic animals, which were taken from the south coast of New South Wales.
• The sera were assessed to determine the presence of Ross River virus antibodies. The identification of such antibodies would indicate a prior infection, and thus exposure to the virus.

Findings

• The results showed that antibodies to the Ross River virus existed in 7% of human samples, 25% of cow samples, and a significant 65% of horse samples.
• Humans and horses were found to be infected with the virus. Tests demonstrated that two human blood donors and a patient from the Nowra-Kiama region had undergone seroconversion – an indication of an active infection.
• Of the seropositive horses, 40% had never left the farms where they were bled, suggesting the virus circulates in the local mosquito population.

Verification of the Findings

• The study was careful to eliminate the possibility that the infections could be due to related alphaviruses, Getah and Sindbis, known to occur in Australia.
• To ensure this, the research team used microneutralization tests against the Ross River virus and the other two alpha-viruses.
• The tests confirmed that the infections were resulting from the Ross River virus and not the Getah or Sindbis viruses.

Implications

• This research confirms the presence of the Ross River virus in the south coast of New South Wales. The fact that some infected individuals had not left the study area indicates local transmission of the virus.
• The study’s findings suggest that there could be an established cycle of transmission involving mosquitoes and mammalian hosts in this region.
• The high percentage of horses carrying antibodies to the virus shows that they could play a significant role as sentinels or amplifiers of the virus, making them an important focus for future surveillance and prevention strategies.