Remember mosquito epidemics: Cases of Japanese encephalitis in Australia

The Australian government has updated its information on the mosquito-transmitted epidemic of Japanese encephalitis virus in states where it has never been reported, i.e., New South Wales, Victoria and South Australia. Only one case has ever been reported previously in Queensland. How this virus reached these large parts of southern Australia is not known, but it is speculated to be related to infected piggeries in all four of these states or possibly via infected waterbirds.

The Culex mosquito species transmit this JE virus. Culex mosquitoes are distinct from the Anopheles mosquito species that transmit malaria parasites. Culex are also distinct from the Aedes species of mosquitos that transmit Zika, dengue, yellow fever and chikungunya viruses.

Before questioning the relevance this JE virus epidemic in a geographically novel part of Australia has to the Americas, it is worth remembering that epidemics involving Zika, Chikungunya, dengue (four serotypes) and even yellow fever virus originated in distant parts of the world and then appeared in the Americas.

On March 15, the Australian government posted the following update on their website:

“As at 14 March 2022:

• there are 18 confirmed human cases of JEV in Australia
• the confirmed cases are in:
• New South Wales (6)
• Queensland (1)
• South Australia (4)
• Victoria (7)”

The life cycle of this virus involving humans, mosquitoes, birds, pigs and sometimes horses appears below from another Australian government website: