Dengue Fever Threat Growing With Climate Warming

[george]

Dengue fever threat growing with climate warming

The increase of global temperature and its adverse affect on health has prompted World Health Organisation (WHO) concern over the spread of dengue fever, that causes 500,000 people worldwide to be hospitalised each year.

Health officials say some 2.5 billion people - two fifths of the world's population - are now at risk from dengue - a severe, flu-like illness that affects infants, young children and adults, but seldom causes death.

Many factors play a role in the increasing threat of emerging diseases - including climate change and adaptation to change by microbes, said WHO's representative to Thailand, Dr Maureen Birmingham.

In dengue fever, the virus type two is transmitted by the aedes aegypti mosquito at 30 degrees Celsius. When temperature increases to more than 32C, the incubation period is shortened and the rate of dengue fever cases increases.

Birmingham said an exception is Bangkok where dengue case rates rise during the hot season with daily mean temperatures of 28 - 30C, and decrease during the cool season with mean temperatures of 25 - 28C.

Dengue viruses are transmitted to humans through the bite of female aedes mosquitoes. Infected humans are the main carriers and multipliers of the virus, and mosquitoes generally acquire the virus while feeding on the blood of an infected person.

After virus incubation for eight to 10 days, an infected mosquito is capable of transmitting the virus for the rest of its life. The virus circulates in the blood of infected humans with a fever for two to seven days.

Studies have shown that monkeys in some parts of the world play a similar role in transmission.

The clinical features of dengue fever vary according to the age of the patient. Infants and young children may have a fever with rash.

Older children and adults may have either a mild fever or classical incapacitating disease with abrupt onset and high fever, severe headache, pain behind the eyes, muscle and joint pains, and rash.

Dengue haemorrhagic fever (DHF) is a potentially deadly complication characterised by high fever, often with enlargement of the liver, and in severe cases circulatory failure.

The illness often begins with a sudden rise in temperature accompanied by facial flush and other flu-like symptoms. The fever usually continues for two to seven days and can be as high as 41C, possibly with convulsions and other complications.

In severe cases, the patient's condition may suddenly deteriorate after a few days of fever; the temperature drops, followed by signs of circulatory failure, and the patient may rapidly go into a critical state of shock and die within 12 to 24 hours, or quickly recover following medical treatment.

According to recent Public Health Ministry records, 5,479 patients nationwide were suffering from dengue fever and six died. Of this number, about 920 patients lived in Bangkok.

A recent WHO report said the number of dengue fever infectious cases in the Southeast Asia region increased from 1,202 people in 2003 to 3,255 in 2008.

The incidence of dengue has grown dramatically around the world in recent decades through growing population and urbanisation, human expansion into wildlife habitat, increasing human interaction with domestic or wild animals, more intensified livestock production systems, and globalisation of food supply systems.

WHO estimates there may be 50 million dengue infections worldwide every year.

Birmingham said WHO has launched the Asia Pacific Strategy for Emerging Disease (APSED), an implementation framework of the International Health Regulations (IHR).

It comprises five pillars: surveillance and early warning, rapid response, laboratory diagnosis risk communications, infection control and biosafety, and zoonosis [spreading of disease from humans to animals] prevention and control.

Prevention, risk mitigation and control of emerging diseases requires not only the establishment of IHR core capacities in every country, but also good preparedness plans to address known threats in the region, she said.

-- The Nation 2009-04-07

[wasabi]

Is there really anything one can do to avoid this during day to day life in Bangkok?

[Norrad]

I had a severe case of Dengue fever about two weeks ago. Spent a few nights in hospital with a drip in my arm and I lost a crapload of weight from dehydration. It really makes you feel like you are dying but isn't that dangerous. The doctor was considering a blood transfusion in my case as my white blood cell count was way below average level.

[Sheryl]

Is there really anything one can do to avoid this during day to day life in Bangkok?

Bangkok or elsewhere, only things one can do are to avoid mosquito bites. It's a day time mosquito so if you are going to be somewhere you may get bitten, use repellant.

If there are rainwater jars near your home treat with larvicide, add tilipia fish or keep covered with a net, the mosquito vector breeds in very stagnant water and water ciollection jkars are a prime spot. Likewise try to avoid any stagnant puddles near the home through proper drainage. The mosquito does not fly very far, simply arranging the yard so that water runs off further from the house before pooling can make a difference.

And lastly -- don't panic. Somehow tropical disease always seem more dangerous to us than the ones we have back home. Dengue is no picnic, but the vast majority of cases are uncomplicated and the severity of symprtoms falls along a spectrum from so mild you barely know you have it to bone-breaking fever&chills. I've had it twice, first time sever and in hospital for 2 weeks, second time mild. Back when there were refuges camps along the Cambodian border and hundreds of (non-immune) farang owrking in them, I saw plenty of farang walk around and not even miss work with the mild form...and a few unlucky ones be levelled for a week or two. Frankly we all regarded it as a rite of passage. (Which is not to say you shouldn't do what you can to avoid it...but keep things in perspective.)

[evitas]

The second infection was not as bad for you?

I thought that following infection becoming worse.

[Sheryl]

What you are thinking of is the comparatively rare (but very serious) form of the disease, dengue hemorrhagic fever, which is thought to involve an auto-immune reaction and thus usually occurs with second, thuird etc infections. However it does not always or even usually occur with subsequent infections; most second/third/fourth bouts of dengue are just simple dengue.

[poldebol]

Very good and practical site from Singapore government on dengue and its prevention:

http://www.dengue.gov.sg/

Anybody knows what brand of "sand granular insecticide" available in Thailand?

[TVmonitor]

I had a severe case of Dengue fever about two weeks ago. Spent a few nights in hospital with a drip in my arm and I lost a crapload of weight from dehydration. It really makes you feel like you are dying but isn't that dangerous. The doctor was considering a blood transfusion in my case as my white blood cell count was way below average level.

apart from if you die!