Mosquito-borne diseases

Mosquito-borne diseases are caused by the transmission of a pathogen (e.g. virus, parasite) from an infected mosquito to a person. Mosquitoes transmit disease-causing pathogens when the adult female seeks out a blood meal, required for egg maturation. Transmission can only occur through the bite of an infected female mosquito and not by direct contact with another individual or animal.

During the transmission cycle, female mosquitoes pick up pathogens from one vertebrate host (either animal or human) and pass them on to another, in subsequent blood feeds. Symptoms of disease may or may not occur.
Mosquito-borne diseases in WA

In Western Australia (WA) there are four mosquito-borne diseases of public health significance, all are caused by the transmission of viruses. These diseases include:

Infection in people can be asymptomatic but are also associated with debilitating and potentially fatal symptoms.

Virus transmission in WA

In nature, the viruses that cause RRV, BFV, MVE and KUN diseases are passed back and forth in a cycle between wildlife (vertebrate hosts) and vector mosquito species. Infected animal hosts play an important role in pathogen transmission but rarely display clinical signs associated with disease. Whilst it’s possible that people can contribute to transmission, they are generally considered dead-end hosts for those viruses acquired in WA. 

People are at risk of infection when they are in close proximity to the virus transmission cycle.  As urban sprawl continues to encroach upon natural mosquito breeding and wildlife habitats, this risk continues to grow. 

The Department of Health runs a surveillance program to determine when mosquito numbers are on the rise and virus is active within the environment. This information is used by both local government and the Department of Health to inform mosquito management activities and issue media statements regarding the increased risk to public health.

Exotic mosquito-borne diseases

If travelling overseas or interstate (northern Queensland, in the case of dengue), it is important to be aware that mosquitoes can transmit a range of other exotic pathogens. Common mosquito-borne diseases acquired outside of WA (Healthy WA site) include:

  • dengue
  • malaria
  • chikungunya
  • Japanese encephalitis
  • yellow fever 
  • Zika

Local transmission of dengue, malaria, chikungunya, Japanese encephalitis, yellow fever and Zika currently does not occur in WA. This is because the mosquitoes that commonly transmit these pathogens are not present locally. However, these diseases may be acquired while travelling overseas so appropriate precautions (Healthy WA site) should be taken. 

More information

Medical Entomology 

Phone: (08) 9285 5500  

Email: medical.entomology@health.wa.gov.au

Last reviewed: 11-02-2020
Produced by

Public & Aboriginal Health Division