The warm autumn and early spring weather has extended the mosquito danger season in Northern NSW.
The warm autumn and early spring weather has extended the mosquito danger season in Northern NSW.

BITTEN: Spike in diseases transmitted by mosquitoes

THE number of cases of diseases transmitted by mosquitoes has skyrocketed in Northern NSW.

In a year with more rain and high temperatures, health experts believe prevention will be the key to keeping these diseases at bay.

So far in 2020, there have been 427 reported cases of Ross River virus in the Northern NSW Local Health District. Most of these cases were reported during Autumn.

That number excludes cases reported after December 7, and it's a five-times increase from the 77 cases recorded in 2019.

In 2015, the total number of cases of Ross River virus was 463, the highest in the last 20 years.

 

Ross River virus notifications in Northern NSW local health district residents, by month of disease onset. January 2017 to December 2020.
Ross River virus notifications in Northern NSW local health district residents, by month of disease onset. January 2017 to December 2020.

 

NSW Health data for the Barmah Forest virus shows 267 cases recorded in Northern NSW before December 7, with 62 patients reported in 2019.

Between 2000 and 2015, the Northern NSW Local Health District used to normally record more than 200 cases of Barmah Forest virus a year, but in the last five years, the numbers had rarely gone above 100 cases a year, until now.

The key is the amount and number of mosquitoes present in the area, according to Medical Entomologist Assoc/Prof Cameron Webb from NSW Health Pathology.

 

mosquito cells infected with Ross River virus that is green fluorescing
mosquito cells infected with Ross River virus that is green fluorescing

 

Mr Webb is an academic at the University of Sydney and also works as a medical entomologist for NSW Health.

"Mosquitoes are a major public health concern," he said.

"In (the Northern Rivers) region, you may have more than 100 types of mosquitoes, but there are only a few that cause serious health problems or play a role in the spread of the viruses.

"In Northern NSW, in the case of Ross River virus, for instances, you have a number of mosquitoes in that area that are capable of spreading that virus between native animals and people, and they respond to different environmental conditions."

In Australia, we don't have other serious mosquito-disseminated diseases, such as Zika, Dengue or Malaria, Mr Webb said.

"But those people who get the diseases we have here, even though they are not fatal, they can be severely debilitating," he said.

The medical entomologist published this week a document called Reflections on a highly unusual summer: bushfires, COVID-19 and mosquito-borne disease in NSW, Australia.


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