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Malaria: prevention not cure

Tuesday September 26, 2006

Anthea Rowan

To watch a child slip into the potentially fatal clutches of malaria is terrifying. It?s the speed of their descent from wellness to serious illness that is so frightening: at dawn they are fine, by dusk they could be in a coma. A coma from which they might never wake. I know this because several years ago I was there - panic-stricken - watching my then eight-year old son, his mind drowning in delirium and his young body hotly racked with fever as he teetered on the brink of collapse. He begged me to ?Just let me close my eyes for a bit, mum,? and, desperate, I pleaded with him to stay awake. His decline - from apparent perfect health to a life-threatening condition - took less than six hours. In the end he was fine - it meant an emergency airlift, an admission to hospital where he was administered Artemisinin (a drug derived from the plant Artemesia annua) intravenously and four long recuperative weeks out of school - but he did make a full recovery. We were lucky, luckier than the parents of the estimated 5,000 children that die from malaria every day.

Malaria is the world?s biggest killer. It affects almost 500 million people a year and takes the lives of nearly 3 million - mostly in Africa, where a child is estimated to die from the disease every 30 seconds - at an estimated cost to the economy of more than 6 billion per annum.

Despite its much publicized Roll Back Malaria Partnership, the World Health Organisation has had limited success in twenty years. The only real impact the programme has had on the disease is through the introduction of Insecticide Treated Nets (ITNs), which are an effective prophylactic, particularly for children, when used correctly (but which remain heavily taxed in much of Africa). Most of the world's millions of malaria sufferers are still not benefiting from life-saving drugs nearly five years after the World Health Organisation urged their widespread use. Since 2001, the UN health agency has recommended countries switch to artemisinin-based combination drugs - or ACTs - to treat malaria which has become resistant to conventional medicines like chloroquine. Despite this, fewer than half of the countries in Africa have.

The majority of sufferers understand very little about the disease or how it is transmitted (by the female anopheles, which must be pregnant, and which only bites between dusk and dawn).

Ronald Ross, a British doctor born in India, was responsible for confirming that is was the mosquito that transmitted malaria and how. Until then the popular theory was that foul-smelling gases emitted from swampy soils caused the disease - the word ?malaria? comes from the Italian, ?bad air?. The mortality rate at the time ? over a million deaths a year - was reduced to less than 10,000 during the 1950s as a direct result of education and the eradication schemes initiated by Ross. Since the 60s, though, the disease has been on the increase - in 1960 only 10% of the world's population was at risk; that figure now stands at over 40%. Today, as a result of poor vector control, global warming and intercontinental travel, malaria infects one in 10 of the world?s population, it is present in over 100 countries (including Eastern Europe, Russia and Turkey) visited by more than 125 million tourists every year, up to 30,000 of whom fall ill when they get home; last year 1,754 Britons contracted malaria abroad; 1,300 of them the deadliest strain, Plasmodium falciparum (or cerebral malaria). Eleven of them died.

Poverty and poor education compound the problem of malaria in third world countries, elevating mortality rates. Astonishingly ignorance of the disease ? despite the press coverage it receives and access to world-class medicine ? is a factor in first world infection too. Most British travellers who became infected with malaria last year admitted to failing to take correctly ? or at all ? oral malarial prophylaxis when visiting areas where the disease is endemic. An investigation conducted earlier this year in the UK found that travellers who sought advice from alternative health centres (complaining drugs prescribed by their GPs were making them feel nauseous) were being offered ?dangerous? advice on malaria prevention and being recommended unproven homoeopathic remedies in lieu of those conventional drugs prescribed by GPs which include ? for example ? a combination of chloroquine and proguanil, mefloquine (Lariam), doxycycline and Malarone. As a resident in Africa I questioned my own doctor about the efficacy and side-effects of these drugs. He dismissed chloroquine and proguanil as being almost useless since the parasite has been shown ? in this region anyway ? to have developed significant resistance to this combination. Lariam, he said, can cause serious neurological disturbances in as many as one in ten people and indeed its prescription is contraindicated in anybody with a history of mental illness. Doxycycline increases photosensitivity so patients must be prepared to stay out of the sun. It also can interfere with the efficacy of oral contraception. Malarone, the most recent anti-malarial to be registered, is considered both effective and relatively easily tolerated, if expensive.
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It is inconceivable that any short-term visitor to a malarious area should not have sought sound advice from the experts (which include the London School of Hygiene and Tropical Medicine, the WHO and the Health Protection Agency on malarial prophylaxis beforehand. The situation, however, is rather more complicated for expatriates living in endemic areas, partly because of the risk associated with long-term use of chemoprophylaxis and partly because there is limited data available on the sustained use of some drugs.

The HPA suggests that ?The risk of serious side-effects associated with long-term prophylactic use of chloroquine and proguanil is low. However, anyone who has taken chloroquine regularly for over five years and requires further prophylaxis should be screened twice-yearly for early retinal changes.? Even before these may become apparent, however, there might be other intolerable side effects: my husband, for example, is unable to take proguanil (Paludrine) for it gives him appallingly bad mouth ulcers which render him unable even to eat. Research suggests there is no increased risk of serious side-effects with long-term use of mefloquine (Larium) assuming a person can tolerate it in the short term. Experience with doxycycline for long-term use is limited, though available data is reassuring (though like mefloquine it must be avoided during pregnancy). In many parts of the world, however, oral prophylaxis ? especially of the most dangerous form of malaria, Plasmodium falciparum ? is not a guaranteed form of protection; P falciparum is increasingly resistant to various antimalarial drugs (indeed my son was on a chloraquine/proguanil combination when he contracted this particularly virulent strain of the disease). As the WHO warns, no antimalarial prophylactic regimen gives complete protection.

Those travelling to malarious areas for extended periods of time (over six months) ? or living there (particularly in the case of women, who may become pregnant, and young children) ? need to balance the risk of infection against the benefits and side-effects of oral prophylaxis; sometimes taking a pill daily gives a false sense of security and might result in individuals being lazy about applying other prophylactic measures ? sleeping under nets, for example, spraying rooms or burning mosquito ?coils? at night. Expatriates ? 30% of whom develop malaria within two years ? need to be vigilant about not being bitten rather than relying on chemoprophylaxis alone, for increasingly chemoprophylaxis is shown to be insufficient protection. Prevailing guidelines, as laid out by the WHO and HPA, promote four ? ABCD ? principles of malaria protection:

  • Be aware of the risk, the incubation period (from 7 days up to several months) and the main symptoms: flu-like to begin with, chills, headache, nausea, sometimes a cough develops.
  • Avoid being bitten by mosquitoes, especially between dusk and dawn ? apply mosquito repellant to the skin, wear long sleeves, trousers, socks and shoes, sleep under a Light in a room where a coil is being burned. Sleeping under a fan or in an air-conditioned room can also help, as can fixing mosquito mesh to windows.Take antimalarial drugs (Chemoprophylaxis) when appropriate, and as advised by a GP, to prevent infection from developing into clinical disease.
  • Immediately seek diagnosis and treatment if a fever develops one week or more after entering an area where there is a risk of malaria, and up to 3 months (and even longer) after departure from a risk area. Early diagnosis and treatment can be life-saving; P falciparum can be fatal within 24 hours. A blood sample should be examined for malaria parasites. If no parasites are found in the first slide yet clinical suspicion of malaria remains, a series of blood samples should be taken at 6 to12-hour intervals and examined vigilantly. Sometimes taking a chemoprophylaxis can mask results so this should always be mentioned to an examining doctor.

In the end, as my doctor here observes, the only sure fire way to avoid infection in a malarial area is to avoid being bitten.

For more information visit:

www.hpa.org.uk
www.lshtm.ac.uk/contact/medadvice.html



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