Mosquito bourne diseases cause concern in three areas of Australia

Feb 25 2008

Australian Health officials have issued public health warnings about mosquito bourne diseases in three areas.

The Greater Southern Area Health Service have discovered Murray Valley encephalitis (MVE) in mosquito samples in Griffith; the Bass Coast Shire Council is warning of reports of Ross River virus on Phillip Island and health experts in the far north are calling for immediate action following outbreaks of Dengue fever in Port Douglas and Mossman.

Murray Valley encephalitis (MVE) can cause death or permanent brain damage in humans and the symptoms include a severe headache, neck stiffness, delirium, vomiting, fever, lethargy or tremors and there is no vaccination or cure.

The MVE was discovered during routine testing for arboviruses or mosquito borne diseases in the irrigation area and as yet no human cases have been detected.

Greater Southern's Tracey Oakman, director of public health, for the Greater Southern region says residents of the Griffith area and visitors should protect themselves from mosquito bites to avoid contracting MVE.

The cases of Ross River virus have prompted the Bass Coast Shire Council to also warn residents and visitors to take precautions.

Ross River fever is a debilitating viral illness which is also carried by mosquitoes, is usually contracted around water during the warmer months, and can be diagnosed by a blood test.

Symptoms of the virus include fever, rash and joint pains; swelling of joints may also occur, especially in the fingers, wrists and feet and joint stiffness tends to be worse in the morning; nausea, headache, backache, and muscle aches are also common along with lethargy and fatigue which are often debilitating, with some people unable to carry out minor activities, or even get out of bed.

Symptoms of the virus usually appear between five and 14 days after infection and disappear within six weeks, however, 10 per cent of people have ongoing joint pains, depression and fatigue for many months.

In many cases, particularly in children, infection with Ross River virus may cause no symptoms at all.

Residents and visitors have been warned to use insect repellant and wearing appropriate clothing when outdoors which covers arms and legs and other exposed areas.

The Dengue fever cases in the north, ten in all to date, are thought to have been spiked by heavy rain falls which have boosted breeding sites.

Dengue fever and Dengue hemorrhagic fever are acute febrile diseases, found in the tropics, also carried by the mosquito.

Typical symptoms include sudden fever, severe headache, muscle and joint pains often severe joint pain hence the nickname break-bone fever or bone crusher disease and a bright red rash.

The Dengue rash usually appears first on the lower limbs and the chest and in some patients, it spreads to cover most of the body.

There may also be gastritis with abdominal pain, nausea, vomiting or diarrhea.

Some cases develop much milder symptoms which can, when no rash is present, be misdiagnosed as influenza or other viral infection and travelers from tropical areas may inadvertently pass on Dengue in their home countries.

Patients with Dengue can pass on the infection only through mosquitoes or blood products and only while they are still febrile.

Dengue fever lasts about six to seven days but the nastier version, Dengue hemorrhagic fever, can lead to Dengue shock syndrome (DSS) which is very often fatal.

Health officials are warning residents of the tropical region to check for potential breeding sites such as discarded containers, old tyres etc, and to slap on insect repellant.