Health

What You Need to Know about Dengue Fever

Gary Anderson realised he had to get to a hospital quickly. While on holiday in rural Indonesia, he had been bitten by a mosquito. A few days later he had woken up with a fever and body aches which he put down to overexertion, but after two more days, Gary realised the nausea and blinding aches in his eyes were bad signs. It was time to get to hospital, quickly, but by then it took him an hour to cover the 50-odd metres of stairs, pavement, and tarmac to reach the car.

Most expatriates know that dengue is a mosquito-borne fever, but little else. Many think it’s like a bad flu, mumps or measles. If you are one of the fortunate few, you have mild symptoms, but the rest experience varying levels of misery. A failure to recognize dengue while on holiday or far from medical treatment can be very serious indeed.

AN ANCIENT DISEASE
Dengue, like its cousin Yellow fever, is mainly carried by the Aedes aegypti mosquito. Dengue is present in almost all tropical regions and, in the last few years, it has entered temperate regions by travelling with Aedes albopictus, a versatile new carrier which also serves European and North American routes. Unlike other mosquitoes, Aedes do not lay eggs in water, and their eggs can remain dormant for a year yet hatch in a day when conditions are right.

The modern name dengue comes to us via Spanish from Swahili ka-dingapepo or the “disease of the devil.” The precise origin of dengue is not known but it is believed to have originated in the Nile area thousands of years ago. The Bible mentions how the hunter-warrior Nimrod repudiated God and assembled a mighty army to challenge the prophet Abraham, who responded with a legion of mosquitos that decimated Nimrod’s soldiers; the first recorded use of biological agents in warfare. In the Quranic version, just one mosquito attacks Nimrod and fells him.

Mosquitos also defeated armies in later times. In 1741, a Royal Navy flotilla and a British army of over 20,000 besieging the Colombian port of Cartagena returned to England a year later, having abandoned the attack. Only 3,000 fit men were left, the rest prostrated by fever and the dead thrown to the sharks. But the mosquitoes were already on the ships, breeding belowdecks like alien stowaways, and continued to feed as the troops fled home.

Mosquitos took their toll in the Pacific and Vietnam wars as well. At Buna-Gona in New Guinea, a major battle with more casualties than Guadalcanal, 66% of casualties were due to malaria and dengue. DEET, the most widely used insect repellant today, was the resultant product of military research to avoid future calamities.

Dengue is spread by mosquitoes hitching rides. Coastal trade along the Indian Ocean rim from Zanzibar to the Malay Peninsula and Sumatra was well-established by the 1st century AD. During the Jin dynasty (265-400 AD), a report of a possible dengue outbreak was reported in China. Dengue entered Western consciousness in the age of maritime exploration and conquest. The slave trade and the spice trade facilitated dengue’s globalization. By the 18th century, Western ships girdled the world from Europe, around Africa to India and the Far East across the Pacific to Central America and then to the American colonies. It was in Philadelphia where dengue was first medically described by Benjamin Rush, a doctor and “Founding Father” – a signatory to the Declaration of Independence and framer of the US Constitution – who treated an epidemic in 1789. He gave dengue its earlier name – break bone fever – because of the joint and muscle pains. This was the first time it occurred simultaneously in several countries around the world. The second pandemic came with World War II and the movement of large amounts of people and cargo.

I’M ILL, NOW WHAT?
Avoid the “surfer’s cure” – i.e., lots of beer to sleep it off. If you have just been infected – the first day of your symptoms – there is a new test which can give an indication. Unfortunately, once the first two days pass, it doesn’t show up. Antibodies appear around day 4, so by then you are just going to have to put up with the headaches and other pains, placing your trust in Panadol and lots of non-alcoholic fluids. Under no circumstances take aspirin as it prevents clotting. On days 5-7 you will start to feel better, and, if you are a first-timer, you may think it’s over. No such luck – dengue is a bi-phasal fever, or in other words, it’s a double whammy. This is a critical period and new symptoms like nausea, abdominal pain and breathing difficulty may develop. Previous medical thinking distinguished between dengue fever and the much more serious dengue hemorrhagic hever. Recent opinion, however, is that these are just ends of the dengue spectrum.

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The fever and pains may return in varying intensity the main concern is whether hemorrhages develop and to what degree. Initially, some bleeding is not uncommon as the small capillaries start to leak. This can manifest as rash-like symptoms – small red dots called petechaie – or involve larger blood blisters. The dengue virus suppresses bone marrow function and your body stops producing white blood cells and the clotting agents, platelets, leaving you vulnerable to infections and external and internal bleeding.

By this time, your doctor should be giving you a blood test every two days. Watching the platelet countdown is morbidly fascinating. Two numbers that you may want to note are 50,000, the level at which surgery is not recommended, and 15,000, the level at which the World Health Organisation recommends blood transfusions.

A WORD OF ADVICE
If all the above happens, it’s best to avoid hazardous activities or contact sports like rugby. Even standing too long might have consequences. I followed my little son on a school excursion during my first bout of dengue. After a couple of hours my legs felt heavy. The capillaries had burst and my swollen calves and feet were bright red-pink like a Saveloy sausage. I know from experience that the best thing to do is lie in bed with your feet raised, drink lots of juice and water, and have the family wait on you hand and foot.

Skin hemorrhages or not, the really worrisome consequence is fluid buildup within the abdomen and lungs which can lead to circulatory failure and death. Untreated, the mortality rate is 20%.

The good news is that only 4% of dengue cases develop the full disease and that a modern hospital should be able to reduce the incidence of mortality to less than 1%. Another bright note is that there are only four dengue serotypes at the moment and, if one is contracted, you will be immune to that serotype in future. The bad news is that the chances of having hemorrhagic dengue increase the next time since, like armies, your antibodies are trained only to fight the previous invaders.

Dengue is set to increase as more parts of the world become warmer and suitable for the Aedes mosquitos to spread. Dengue also illustrates the folly of habitat destruction: like HIV, dengue was a forest disease of apes and monkeys. Both the virus and its mosquito vectors have adapted to urban life and now these mosquitos feed almost exclusively on humans. This led to the third surge in the dengue pandemic: hyperendemicity. The highest incidences of dengue are now in cities and towns.

We should be mindful of history; it is the little things that can bring down civilisations.

 

This article was written by Ashleigh Seow for The Expat magazine and has been edited for Expat Go.
Source: The Expat April 2012
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