otherwise healthy, active and productive patients. The safety requirements for prophylactic agents clearly need to be stringent. With the continuing expansion of ...
Journal of the Royal Society of Medicine Supplement No. 17 Volume 82 1989
Editorial
2 8 NOV 1990 f
Falciparum malaria in Britain Malaria in Britain is changing; sadly, for the worst. Both general practitioners and hospital physicians need to be alert to these changes for they affect the management of patients. Firstly, there has been an alarming increase in the number of cases of infection due to Plasmodium falciparum, the type of malaria which is often fatal if inadequately treated. In the 1970s, a few hundred cases with infection due to this species were reported in Britain each year, mostly in foreign immigrants. By 1988, over 1000 cases were reported annually, principally in British citizens. 1989 figures are even higher. Secondly, antimalarial drugs are losing their effectiveness for both prophylaxis and treatment of P. falciparum infections. Parasite resistance to chloroquine and proguanil, two of the safer antimalarial drugs, is now widespread throughout Africa and Southeast Asia. More and more frequently, British travellers who take antimalarial prophylaxis are found to be infected with malaria and require special therapy to ensure that their infection is brought rapidly under control. Once infected with P. falciparum, the prognosis for nonimmune British citizens is worrying; for example, there was a case fatality rate of 1: 18 in the 60 British travellers infected with P. falciparum from Kenya in 1987. Thirdly, some of the newer drugs, to which the parasites remain sensitive, have been associated with serious adverse drug reactions. This creates a particular burden for physicians who clearly wish to ensure that they offer the best available prophylactic cover, but who will be highly reluctant to prescribe drugs that could cause life threatening reactions in otherwise healthy, active and productive patients. The safety requirements for prophylactic agents clearly need to be stringent. With the continuing expansion of travel to malarious areas each year, an increasing number of British citizens will be exposed to multi-drug resistant P. falciparum infections. The numbers are not insignificant; in 1987, 1.6 million British citizens visited malarious areas, about 100 000 of them visiting the countries of sub-Saharan Africa where transmission of P. falciparum is particularly high. General practitioners and hospital physicians can expect to be confronted more frequently with patients seeking prophylactic advice, and with returning travellers who may be infected with falciparum malaria. However, information on malaria, in a format appropriate for general physicians, is scanty and much of the key information is widely dispersed in inaccessible journals. A one-day symposium, held at the Royal Society of Medicine in London on 1 June 1989, aimed to bring together specialists who could provide physicians with this important information. The papers presented at the symposium by these clinicians, epidemiologists, entomologists and immunologists offer a comprehensive and up-to-date review -
of the clinical aspects of malaria and its control. These papers form the subject of this supplement to the Journal of the Royal Society of Medicine. In this volume, physicians are introduced to malaria as a disease once endemic in Britain. Dr Dobson conjures up a picture ofthe devastating effect malaria had on the lives of residents of the English marshlands. The old evil that then rose from the mists, miasma and the marshes was well known to Heberden and generations of English physicians. Professor Bradley then, in these pages, assures us that malaria will not return to Britain as an endemic disease but his informed account of the changing trends of imported malaria alerts us to the increased incidence of P. falciparum infection. The principal reason for this increase, the development of parasite drug resistance, is described by Professor Peters. The search for antimalarial drugs to which the parasite will remain sensitive has required exceptional resources, effort and dedication. Only a handful of the 300 000 or so compounds which have been screened have proved to be effective and safe enough for human consumption; and the development of resistance to these seems to be inevitable. Alternative means of control, thus, become imperative; Dr Curtis explains the various methods available to reduce bites from the female anopheline mosquito and he advises which ofthese offers the greatest degree of protection. While anti-mosquito measures do reduce bites, the risk of malaria infection in non-immune subjects, once bitten by an infected mosquito, is high. Effective antimalarial prophylaxis for travellers to areas with high transmission rates is, therefore, essential. Unfortunately, the information available on the efficacy of drug prophylaxis is inadequate but the data do suggest that the efficacy of antimalarial drugs has fallen substantially in recent years. This might lead us to look at drugs of greater potency in an effort to provide more complete protection. This, however, can lead us to use drugs capable of producing rare but very serious adverse drug reactions and, in this symposium, Dr T Peto argues that, with such drugs, the risk of a fatal outcome from a serious adverse reaction can be higher than the risk from malaria. If such risks are unacceptable, and safer but less effective drugs are prescribed, physicians must be aware ofthe possibility of increased numbers of cases. Early diagnosis becomes essential and, in this supplement, the presenting signs and symptoms of malaria in children and in adults are described by Dr Molyneux and Dr Ellis, respectively. It is clear that vigilance is required to differentiate P. falciparum infections from other infectious diseases. Diagnosis can be supported by a number of techniques, and, as discussed by Dr Chiodini, identification of the parasite in a blood smear examined microscopically remains the principal means of establishing the diagnosis. Rapid and appropriate treatment of P. falciparum infections is crucial; deaths have been reported within 24 hours of the onset of classical symptoms. Professor Warrell
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Journal of the Royal Society of Medicine Supplement No. 17 Volume 82 1989
provides comprehensive guidelines on the best current treatment of severe malaria. Will science offer us alternative forms of protection in the near future? The status of vaccine research and future prospects are, in this volume, succinctly discussed by Professor Targett and Professor Hommel. The diversity of the malaria parasite and its ability to circumvent immunological progress suggest that we cannot depend on the immediate promise of a vaccine. Chemotherapy must, therefore, remain an essential component of malaria control; Dr Gutteridge indicates that alternative drugs are undergoing trials and may offer improved protection without untoward side effects. Finally, the information in these proceedings is summarized by Professor Bradley, who discusses malaria control in the context of the role of the physician in Britain. This summary brings these proceedings to a close in a way which, if it serves to increase clinical awareness of the changing problem
of malaria in Britain, will be of great reward to those who organized and contributed to this lively and informative symposium. It remains necessary to record one very sad matter: Professor Bruce-Chwatt, known and respected throughout the world for his outstanding contribution towards the study of malaria, was invited to contribute to these proceedings but died shortly before the conference. Thus, in recognition of our great respect and loss, these proceedings are dedicated to the memory of Leonard Bruce-Chwatt whose scholarship has made a permanent contribution to the study of malaria. Ronald D Mann Medical Services Secretary Royal Society of Medicine Penny A Phillips-Howard Research Fellow London School of Hygiene and Tropical Medicine
