Severe malaria

8 Severe malaria Malcolm Molyneux At a hospital in the United Republic of Tanzania, a mother watches as her child lies in a coma with severe malaria . Photo WHO/TOR/ A. Crump At a rural clinic in tropical Africa, it would not be unusual to find each of the following patients waiting for attention: • a man complaining of feverish- ness for the past two days; he is still able to work, but wants treatment to make him feel better; • a child whose mother is worried because the boy's hands and lips have become almost as pale as paper, and he seems less ener- getic than usual; • a young girl who is hot, deeply unconscious and having repeated convulsions of the whole body; her brother died the previous year during a similar illness. Each of these patients is suffering from malaria. For the first, it is simply a nuisance; for the second, profound anaemia has developed, which could be fatal if untreated; for the third, the function of the brain has been affected and the child is in danger of losing her life. We refer to the illnesses in the second and third of these individuals as different forms of severe malaria. Why can malaria parasites cause such different kinds of illness in different people? We know some of the contributing reasons. • The species of malaria parasite is important - only Plasmodium falciparum causes severe disease, in some people - and we believe that there are differences even between strains of P. falciparum in their capacity to cause disease. • The immunity of the individual also affects how ill a person becomes when infected with malaria parasites. The first patient described above was probably protected by immunity acquired slowly over years of repeated infection. We also know that some people are genet- ically less susceptible than others to severe illness when infected with P. falciparum . Which individuals in a community are most at risk of severe malaria? This depends on their exposure to the infection. Where transmission is intense, everyone is infected in early childhood and some of those chil- dren develop severe disease, which World Health • Slst Year, No. 3, Moy- June 1998 Once severe malaria develops, extra facilities are usually needed to give the paffentadequaterreatment A drug that can easily be given in a village setting, perhaps while waiting for transport to carry the patient to a hospital, can be /if e- savmg. may prove fatal. Over a million children die every year in this way. In such populations, those surviving to adult life have acquired some immunity, and tend to suffer only mild illness when again infected with the parasite. Low immunity Where transmission is only occa- sional, or occurs only in some parts of a country, people do not have the opportun ity to become immune; malaria is a Jess common problem, but people of all ages are at risk of severe disease if they become in- fected. Similarly a traveller from a non-endemic country is at risk of severe disease when visiting an area where P. falciparum is transmitted. Prompt and effective treatment may prevent a malarial fever pro- gressing to severe disease, or may save the life of a person who has already developed severe malaria. For many of the people most at risk of malarial infection, getting good treatment quickly for a fever can be difficult or impossible. This is the story told by the mother of a child brought in unconscious one evening World Health • 51 st Year, No. 3, Moy-June 1998 to a hospital in a country where there is intense year-round transmission of P. falciparum. "B. was completely well yester- day (Tuesday) morning. At midday he did not want his food and felt hot to touch. I wondered whether to go to the clinic, but the mobile clinic is only on Mondays and Thursdays, and the health centre is five kilometres away, it was raining heavily and there is no transport. So I bought a tablet of chloroquine from the gro- cery shop, and forced him to swallow it. This morning he was still hot and weak, and then his whole body started jerking. So I took him to our village healer, who applied a mixture to the child 's head. As he remained unconscious for many hours, my brother helped me to carry him to the health centre by bicycle. The nurse at the health centre said B. needed an injection of quinine, but it was out of stock. She ordered an ambulance, which arrived after about four hours, and it took an hour to drive us here." In hospital this child was immedi- ately given an infusion of quinine, together with glucose and fluids. Further seizures were treated with anticonvulsant drugs, and he needed a blood transfusion for rapidly pro- gressing anaemia. After 28 hours of continuing coma, he regained con- sciousness and made a full recovery. Thousands of similar stories could be told every week. Often the outcome is not so happy: the child may die at home, or on the attempted journey to hospital, or in hospital because the treatment is administered too late. Some children who recover from a malarial coma are left with disabilities such as partial paralysis, deafness, blindness or mental impair- ment. In the case of non-immune adults, severe malaria is often the result of delayed diagnosis of early symp- toms. The delay may be due to patients assuming that they are suf- fering from some minor fever, or it may be due to doctors diagnosing a less dangerous condition such as influenza, bronchitis or hepatitis . 9 A patient with severe anaemia due to Plasmodium falciparum arrives at a district hospital in Viel Nam. Transporting such patients as quickly as possible can save their lives. Photo WHO/ TDR/ 0. Martel Education is the key What can be done to reduce the burden of severe disease and death due to malaria? Education - by radio, at school or in village meetings - may help people to know the possi- ble dangers of malaria and how they might reduce these dangers. Doctors and health workers at all levels need to be aware of when to suspect malaria and how to diagnose and treat it properly. Preventing mosquitos from inoc- ulating parasites into humans - for instance by the use of insecticide- treated bednets - has been shown to reduce the number of deaths in chil- dren. Such measures can have an important impact, although they cannot prevent all infections or all severe disease events. Prompt treatment of malarial fever can reduce the chance of that fever progressing to severe malaria. This requires a treatment which is effective against the local strains of P. falciparum and available close to where people live. Where health services are distant, shopkeepers can help by stocking essential antimalar- ial drugs, provided they can give people the right advice about how to use the drugs properly. When health services are within reach, they need to have stocks of the necessary drugs, as well as staff who can recognize malaria and treat it correctly, espe- cially if signs of severe disease are beginning to appear. Unfortunately, even with early diagnosis and treat- ment, malaria may progress to the severe stage Once severe malaria develops, extra facilities are usually needed to provide adequate treatment. A drug that can easily be given in a village setting, while waiting for transport to carry the patient to a hospital, can be life-saving. Artemisinin compounds are used in this way in parts of south- east Asia and are being studied in Africa. Improved transport and communications will themselves improve access to treatment for people like the woman and her child described above. Meanwhile vaccines against malaria are being tested. Some vaccines may prevent malaria of all kinds; others may simply reduce the risk of a malarial infection progress- ing to severe disease. We must hope that such a development will very soon add to our available weapons against the world's most destructive parasitic disease. • Professor Malcolm Molyneux is with the Wei/come Trust Centre and Malaria Research Project, P O Box 30096, Blantyre 3, Malawi, Africa.