When the Central Coast’s mosquitoes come, and who counted them
This coast has its own count and its own season: the Central Coast Public Health Unit counted the Coast’s mosquitoes at six places, and the arbovirus season there is usually November to April, both in Central Coast Local Health District's release of April 2023. This guide sets NSW Health's advice on the viruses beside what the district records.
The health statements on this page are NSW Health's own, from the pages linked in the footer.
Why this coast is mosquito country at all
Mosquitoes can transmit a number of serious human diseases, and NSW Health names viruses some mosquitoes in this state transmit, such as Japanese encephalitis, Ross River, Barmah Forest, Kunjin and Murray Valley encephalitis viruses.
Mosquitoes need water to breed, and some mosquitoes can breed in very small amounts of water. That sentence is the whole reason a coast of lakes and lagoons has a mosquito question at all, and it is also the reason the answer at home starts in your own yard rather than on the water: the water bodies themselves are not yours to treat.
NSW Health's advice on timing is plain: most mosquitoes in NSW become active at dawn and dusk, and into the evening, and it says to take extra care during those peak times to reduce the risk of infection.
Who is watching, and what watching means
Surveillance, in NSW Health's own definition, is the organised monitoring of levels of virus activity, vector populations, infections and other factors, to detect or predict changes in the transmission dynamics of arboviruses, in an effort to reduce the potential for human disease. In plain terms: someone counts the mosquitoes and tests them, so that a change is seen before it becomes a run of cases.
The state's account of how that is done is concrete. In NSW, the presence of arboviruses in the environment is picked up through surveillance of chicken flocks, trapping of mosquitoes for virus isolation, and by human case surveillance.
The trapping and monitoring is done by the Institute for Clinical Pathology and Medical Research on behalf of Health Protection NSW, and mosquito populations are routinely monitored at up to 30 locations across the state through the months of November to April. At inland locations, the trapped mosquitoes are also tested for alphaviruses and flaviviruses. Across the state, NSW Health undertakes mosquito surveillance from November to April/May each year.
The chicken flocks are inland, not here: the emphasis of that surveillance, NSW Health says, is on the northern, inland areas of the state, where flocks are bled weekly during the season to detect Murray Valley encephalitis and Kunjin viruses.
On this coast, the district's own record is the local part of that picture. The Central Coast Public Health Unit counted the Coast’s mosquitoes at six places, and the district's release of April 2023 names them: Empire Bay and Halekulani, Long Jetty and North Avoca, Ourimbah and Pearl Beach. The arbovirus season there is usually November to April.
The district's release is a reminder as well as a record: it urged people to take steps against mosquito bites after Barmah Forest virus was found in mosquitoes at Empire Bay, in 2023.
One thing the state's surveillance page is careful about is what it is for: its aim is an early warning of Murray Valley encephalitis and Kunjin in the state, in an effort to reduce the potential for human disease.
The viruses NSW Health names, put beside each other
NSW Health's pages describe these viruses one at a time; here they are side by side, in its words.
| Virus | What NSW Health says |
|---|---|
| Ross River | Many people with Ross River virus infection do not have symptoms; when symptoms occur they usually develop about 7 to 10 days after being bitten by an infected mosquito. Most people make a full recovery after a few weeks, and NSW Health notes that others may have symptoms such as joint pain and tiredness for many months. |
| Barmah Forest | Named by NSW Health among the viruses that some mosquitoes in this state transmit. The district records a detection on this coast: Barmah Forest virus was found in mosquitoes at Empire Bay, in its release of April 2023. |
| Murray Valley encephalitis | Most people who are infected do not have any symptoms at all. Rarely, the virus can cause a severe brain infection known as encephalitis, and among those who get a severe infection some may have lifelong neurological complications or even death. |
| Japanese encephalitis | NSW Health describes it as a rare but serious disease caused by the Japanese encephalitis virus, spread to humans by infected mosquitoes. |
| Kunjin | Named by NSW Health among the viruses that some mosquitoes in this state transmit, on the same page that names the others. |
Ross River virus is spread when a mosquito bites an infected animal or human and then bites a human, and it is not spread directly from person to person. There is currently no vaccine against it, and the best way to avoid it is to not get bitten. There is also no specific treatment; a doctor advises on treating the symptoms.
If a bite makes you unwell
NSW Health's own line, word for word: if after a mosquito bite you develop a rash, flu-like symptoms such as fever, chills, headaches, joint or muscle pains (swelling or stiffness), fatigue, or you generally feel unwell, contact a doctor right away, or in an emergency call Triple Zero (000) or visit your nearest emergency department.
The Ross River fact sheet carries the same direction more briefly: if you get these symptoms, contact a doctor right away, or Healthdirect on 1800 022 222, or in an emergency call Triple Zero (000) or visit your nearest emergency department.
For an ordinary bite, NSW Health advises against scratching it, because scratching can break the skin and lead to a wound or an infection, and it says the symptoms of an infected bite include swelling, pain, redness and inflammation.
The timing advice on this page holds for every season, because it is about how mosquitoes behave rather than what a single year is doing. What changes from year to year is the numbers coming off the count, and those belong to the district and to NSW Health to publish. NSW Health's arbovirus surveillance page explains how the state watches each season.