The dengue fever mosquito common to the north and central Queensland poses the greatest danger of spreading the Zika virus in Australia, according to the researchers at QUT and QIMR Berghofer Medical Research Institute. The study of the researchers has been published in PLOS Neglected Tropical Disease.

In the study, the researchers revealed that not only was the dengue mosquito effective at transmitting Zika but also that the virus was in the reproductive organs of the mosquito. This finding suggests that Zika could persist in mosquito populations by female passing it to other offspring.

Highlights of the study include:

  • Zika can be contacted by individuals through the bite from a female mosquito carrying the virus
  • A Zika infected woman can pass the virus to her unborn child causing neurological problems including microcephaly, when the brain does not develop properly and the baby has a smaller than normal head
  • With more than 50 cases of Zika reported in Australia, all of them were contacted overseas

Dr. Francesca Frentiu, the lead author of the study from QUT's Institute of Health and Biomedical Innovation, said that researchers looked at whether two mosquito species discovered in Queensland could transmit Zika, Asian Tiger mosquito (Aedes albopictus) and the dengue mosquito (Aedes aegypti). While the Asian Tiger mosquito is currently only in the Torres Strait, the dengue mosquito is found in northern, central, and southern parts of the state.

Then, the team tested a strain of Zika from the Asian lineage that caused microcephaly during the 2016 epidemic in Brazil.

Dr. Leon Hugo from QIMR Berghofer's Mosquito Control Laboratory and co-author of the study said that the mosquitoes used in the study were hatched from eggs collected from colonies in Innisfail and Hammond Island in the Torres Strait, and reared at the institute's state-of-the-art mosquito and pathogen containment insectary in Brisbane.

Hugo confirmed that their high biosecurity insectary is unique in the southern hemisphere for its size, capacity, and expertise which allowed them to work safely with dangerous pathogens like Zika.

Dr. Frentiu added that the discovery of Zika in the ovaries of the dengue mosquitoes is an indication of another potential route of infection transmission through mosquito populations.

She said that this research has also been observed recently in field specimens collected in Brazil. Aedes aegypti eggs were collected and hatched and the larvae tested, and Zika was found in the larvae. The study concluded that it is possible that if infected larvae were able to reach maturity still infected with Zika, they could then pass the virus to humans. They need further research in this area.