News : 18 October 2001

The price of a life - less than a lottery ticket

A child may die from malaria every 30-40 seconds in Sub-Saharan Africa…..yet many of these deaths could be prevented by providing insecticide-treated mosquito nets - a process which costs less than a UK National Lottery ticket. Malaria haunts over 100 tropical countries where it is endemic, with an estimated 300-500 million cases per year (1997) and between 1.5-2.7 million deaths.

These are the stark facts revealed by Professor David Warrell, Professor of Tropical Medicine and Infectious Diseases at the University of Oxford in his Harveian Oration* at the Royal College of Physicians on Thursday October 18 2001. The first Harveian Oration on tropical medicine in the 350 years of its history, the lecture covers diseases that follow bites from mosquitoes, snakes and mad dogs; outlines how powerless we still are against their potentially fatal consequences; and how the best opportunities for conquering these enemies lie in prevention rather than treatment. Professor Warrell also highlights key research findings and points to areas worthy of further investigation.

Malaria

William Harvey, who founded the lecture in the 17th century, was familiar with malaria and even suffered himself from the disease. Malaria in England at that time was caused by kinds of parasite now regarded as relatively benign, but in those days they apparently caused death and disease. Since then, we have been able to eliminate the risk of death and serious illness from mosquito bites in the UK, but the malarial threat may be returning.

Increased air travel to affected countries, coupled with climate variability, means that we cannot be complacent about malaria. The tendency towards higher temperatures could improve the efficiency of the mosquito as a vehicle for the parasite, and migrant populations who frequently return to visit family and friends in affected areas are at much greater risk of contracting malaria.

Professor Warrell identifies insecticide-treated nets (ITNs) as the most effective population-based method of preventing malaria in countries where it is endemic, as even the best possible treatments for severe malaria are unlikely to reduce deaths to less than 10% of those with severe disease. Several different forms of vaccination and immunisation have been developed and tested, but are only partially effective and tend to work over a limited time period. Until an effective vaccine can be developed for use in endemic areas, more conventional methods must be used.

Non-treated nets were known to prevent mosquito bites as far back as ancient Egypt. By the 1980s, ITNs were producing dramatic reductions of up to 60% in child deaths in villages in The Gambia, where the nets were given out free as part of a national programme. However, the following year, when villagers were asked to pay less than half a U.S dollar for re-treatment of the nets with insecticide, there was a marked drop in coverage.

The nets were also widely used in China and Vietnam with the result that by the end of the 1990s, deaths from malaria in Vietnam alone had been reduced to less than five per cent of the late 1980s total.

Professor Warrell says:
"…the principal practical obstacle to the implementation of such an effective intervention is the lack of enthusiastic promotion in some countries and the cost of providing nets to impoverished inhabitants of malaria endemic areas, particularly in Africa, and ensuring they are re-treated with insecticide every year. There is a strong argument that ITNs, like EPI vaccines, should be provided free, through international donor agencies, or like the spraying of houses with residual insecticides, by governments."

Snake bites

Although not a problem in the UK, snake bites cause an estimated 50,000-100,000 deaths globally each year, a figure that may be an underestimate as many victims seek traditional treatment instead of going to hospital and may die at home unrecorded. In rural areas with no fast access to an antidote, safe and reliable first-aid methods are needed to delay the development of life-threatening envenoming: paralysis, shock, massive bleeding, and acute kidney failure.

It has been known for centuries that tight tourniquets are an effective, if drastic, way of stopping the venom spreading, but in the 1980s a more sophisticated approach was developed in Australia. Compressing the bitten arm with a crepe bandage and splinting it to stop it moving has proved partially effective but it has to be done at exactly the right pressure - this can give the victim time to get to a hospital and has even been shown to work when bitten by the infamous funnel-web spider.

Rabies

Rabies kills an estimated 60,000 people every year, and in 1997 50 million doses of post-bite vaccine were used - again these figures are probably underestimates. Professor Warrell describes rabies as "an appalling disease…..one of the most agonizing deaths imaginable.. ". Also known in Harvey's time, rabies has not been endemic in Britain since the beginning of the 20th century.

The rabies virus is very unusual as it is not carried through the blood, but by nerves to the central nervous system. It can be blocked experimentally by local anaesthetics, metabolic inhibitors and severing nerves - this latter was advocated in the 19th century. Immunisation against rabies was discovered by Viktor Galtier in 1881, followed by Louis Pasteur's first use of rabies post-exposure vaccination on 6 July 1885.

Initially controversial, the value of passive immunisation was shown in 1954 when 11 people in rural Iran, bitten on the limbs and trunk by a rabid wolf, survived after being given the vaccine. New cell culture vaccines are now available, but are still too expensive for tropical countries, so scientists are looking for even cheaper ways of making them available to everyone.

Editors Notes

Professor Warrell will be available for interview under embargo from Monday 15 October onwards. For further information please contact RCP PR Manager Linda Cuthbertson on 020 7935 1174 ext.254, 0794 105 7494 or e-mail Linda.Cuthbertson@rcplondon.ac.uk.

* William Harvey, the eminent 17th Century physician who discovered the circulation of the blood, gave an indenture to the RCP in 1656 for an annual dinner to encourage friendship between Fellows and Members of the College at which there should be an oration “with an exhortation to the Fellows and Members of the said College to search and study out the secret of Nature by way of experiment”. The College continues the tradition by inviting a leading doctor or scientist to give the Oration on issues relating to his or her own field of work.

Journalists: For further information on any story, please contact Linda Cuthbertson, Press and PR Manager on 020 7935 1174 ext.254 or e-mail Linda.Cuthbertson@rcplondon.ac.uk.

This page last updated on May 31, 2005