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Chapter 46

Fevers

"The weariness, the fever and the fret. Here, where men sit and hear each other groan."

John Keats (1795-1821)
Ode to a Nightingale

The feverish illnesses described in this chapter affect many millions of people all over the world, but most commonly and most seriously in the tropics and subtropics. They may be carried by immigrants or affect travelers, often in an unexpected way. In many regions of the world they are an ever-present cause of ill health and, often, death.

For radiologists there are few specific findings, but patients with these fevers will often be referred for imaging because of coma or hemorrhage, or simply in the hope of finding the cause of the ill health and fever. Colleagues may ask for advice on the most appropriate imaging for such cases. All the diseases in this chapter are complex and their natural history has only been summarized; all present diagnostic challenges, for both the clinical radiologist and the referring physician.

Malaria

"Malaria has, over the millennia, accounted for innumerable deaths and shaped the course of human history."

M. Dobson

"There is a danger that, if resistance to drugs continues to increase, malaria will get out of control and claim 10 million lives a year."

A. Hill (1992)

Intermittent and remittent fevers, as they were called in London in 1819, were but continuing evidence of an illness which was known as the ague, the pestilence, or at times the plague of malaria which had for centuries afflicted almost all Europe and the tropical world. It was the result, as everyone then knew, of "atmospheric influence" or "bad air;" hence mal aria, from the Italian. It was all due to the marshes and their vapors, from which came "epidemic miasma" and "paludism" from the Latin for a marsh, "Palus". No distinction was made between the various fevers, and many an ague was actually due to typhus or typhoid. But, if due to malaria, cinchona bark (named by Linnaeus in 1742, perhaps after a countess of Chinchon, the vice-reine of Peru in 1638) became an effective treatment and if no one understood how it worked, they used it because it did!

The malaria parasite was described in 1880 by Alphonse Laverain in Algeria, but over 120 years later the devastation of malaria is still a major health problem. In 1993 the World Health Organization estimated that there were over 200 million people, 40% of the world's population, at risk in 100 countries. One hundred million have the disease and two million die every year, one million in Africa alone. In some countries where malaria is endemic, e.g., Ghana, it may account for 10% of deaths and young children are particularly at risk: in 1991, the WHO estimated that somewhere in the world two children die of malaria every minute. The scale of epidemics can be frightening. In 1994 in the State of Rajasthan (western India), there were 95,165 positive cases of malaria and 255 deaths in 6 weeks: nongovernment teams estimated a far higher number of deaths.

As a result of the speed of modern travel, malaria has returned to Europe and North America and every year cases are seen but not always recognized in temperate, nonendemic countries. For some there is no explanation of how they could have contracted malaria. For example, in 1991 a 70 year-old Frenchman who had lived almost his whole life in southern France, seldom left his home area, and had certainly never been anywhere near an endemic area for malaria, became ill with severe cerebral Plasmodium falciparum malaria. He was fortunate, because the trophozoites were recognized when a blood film was examined because of thrombocytopenia. There were no Anopheles mosquitoes in the area, and the nearest airport was 60-km away. An unsolved mystery, and a reminder.

In the 1950s and 1960s, massive campaigns using residual DDT (paradichlorodiphenyl trichloroethane) seemed to herald successful mosquito elimination by breaking the cycle, but in the last 10 years malaria has again become more prevalent, so that now in many areas it is once more part of the normal life of almost everyone; in some regions over 90% of the people are infected.

What is worse, there has been a rapid increase in the number of parasites which are resistant to all the available methods of prophylaxis. In 1992 the director of the Wellcome Trust (London) found resistance to all recently developed drugs, to the extent that many well-known malaria experts admit (but never in public) that they themselves no longer take preventative drugs, but prefer preventative measures; shirts with long sleeves, long trousers, impregnated nets to sleep under (the risk of infection is much higher after sunset), and drugs ready to treat the attacks when they come. This debate continues, with European and American experts often differing in their advice and doctors in malarial areas agreeing with neither.

At the same time there is hope that before long a successful vaccine will have been developed and progress made in understanding the genetic mechanism which encodes the proteins which are essential for the survival of the malaria parasite: alternatively it may be possible to breed mosquitoes which do not carry plasmodia.

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Copyright: Palmer and Reeder