The problem in Africa

Malaria is one of the major diseases of Africa and one of the commonest reasons for outpatient attendance in most hospitals. Over 90 per cent of this is the potentially fatal P. falciparum species. A recent estimate suggested that, in 2007, 182 million African children under 5 with fever were likely to have sought treatment in a public sector clinic of which 78 million (43 per cent) were likely to have been infected with P. falciparum (Gething et al., 2010). The actual number of cases will be higher; in most countries the majority of children with malaria never get to public sector health care.

Malaria is a major cause of severe morbidity and mortality in children and pregnant women throughout Africa between the Sahara and South Africa. Currently, most non-pregnant adults in malaria-endemic Africa have sufficient immunity following repeated exposure to prevent them dying of malaria, so in adults it is a much smaller problem. Immunity to severe malaria cannot be assumed, however, especially in adults from low transmission settings such as urban or highland areas, or where there is good malaria control.

Diagnosed early and correctly, almost all cases of malaria in Africa should be curable with widely available drugs. When definitive treatment is delayed, often due to delayed presentation or treatment with ineffective drugs, malaria can be a severe disease causing significant mortality in children, and adults especially in pregnant women. Since the third edition of this book, the incidence of malaria has dropped significantly in a number of countries in Africa, notably Zambia, parts of Kenya, Zanzibar and parts of Tanzania, Rwanda and The Gambia. Despite this, malaria remains a major public health problem even in these countries and one of the leading causes of mortality in other African countries. The changing epidemiology of malaria is likely to present new challenges over the life-time of this textbook.

Diphtheria is a disease caused by toxin producing strains of Corynebacterium diphtheriae.

The problem in Africa

Serious diphtheria always seems to have been relatively uncommon in Africa, possibly due to repeated skin infections due to C. diphtheriae (van Geldermalsen and Wenning, 1993). Widespread use of diphtheria toxoid vaccine (against the toxin), has probably also contributed to a low rate of significant diphtheria in Africa and it is now rare, with vaccine rates of DTP vaccine running at around 70 per cent (Arevshatian et al., 2007). Some cases do occur, however, and it is worth being aware of the typical presentation of diphtheria.

Clinical presentation

Classically patients present with a very sore throat or with a very sore nasopharynx with discharge which is bloody. The key to suspecting the diagnosis is to examine the throat, or the nose, which will show a grey–white pseudomembrane which on touching it with a swab is adherent and bleeds when you try to pull it away. Where possible, try and culture diphtheria, but seeing a typical pseudomembrane is sufficiently diagnostic that it should be treated as diphtheria for practical purposes. Nasopharyngeal diphtheria causes two sets of problems, local and general, both caused by toxin. The local effects of diphtheria are to cause massive inflammation of the throat and eventually larynx. Externally this may be seen with swelling and inflammation of the neck (bull neck). This can cause local pressure on the airways particularly around the larynx, which can lead to complete or near complete obstruction.

The problem in Africa

Lymphatic filariasis is a leading cause of permanent and long-term disability. It will continue to be a major problem in some areas of Africa for many years to come. The outlook for the control of lymphatic filariasis has, however, markedly improved recently. In the long term, filariasis is a potential candidate for elimination from Africa.

Loiasis exclusively occurs in Africa where millions of people are infected. In some endemic regions it is one of the commonest causes for medical consultations. Loiasis has recently gained attention due to severe complications observed in individuals co-infected with O. volvulus who were treated with antifiarial drugs.

Organism, life cycle and vector

Both lymphatic filariasis and loiasis are vector-borne infections caused by filarial nematodes.

In Africa lymphatic filariasis is almost exclusively caused by Wuchereria bancrofti. Microfilariae of W. bancrofti are ingested by female mosquitoes (Anopheles, Culex and Aedes spp.) during feeding. L.loa is transmitted by small blood-sucking Chrysops-flies, that live in or near forested and muddy areas.

The problem in Africa

There is a background rate of influenza in all parts of the world including Africa, where influenza may cause around 5 per cent of severe paediatric pneumonia (Berkley et al., 2010). It is indistinguishable from other viral causes of upper respiratory tract infection unless you have access to sophisticated diagnostic facilities. Under ordinary circumstances those who are at risk of dying from influenza are the very young and the very old; there is some evidence the risk is higher in Africa than elsewhere in these groups (Cohen et al., 2010). Outside epidemics influenza is seldom reliably diagnosed and therefore specific treatment for influenza is unlikely to be instituted.

The virus, clinical features and treatment.

Influenza is a single-stranded RNA virus transmitted by droplets in the air or on hands or fomites. Influenza normally causes fever, cough and general malaise. Influenza in Africa is generally a clinical diagnosis. Death can occur both by a primary process caused directly by influenza virus, including a primary viral pneumonia, or later by a secondary bacterial infection of the lungs including with staphylococcus. If you suspect influenza and the case is severe, treating with broad spectrum antibiotics clearly has a role to reduce the risk of this secondary complication. Broad spectrum antibiotics such as doxycycline or co-amoxiclav which would cover pneumococcus and staphylococcus should be used. Where it is available, patients may need respiratory support.

The problem in Africa

Plague remains endemic in several parts of Africa (Fig. 28.1). Its incidence in Africa has probably declined over the last century, but it is unlikely ever to be eliminated, and there may even be an upsurge at present (Neerinckx et al., 2010). Africa currently has 95 per cent of the world's human plague, with an estimated 1800 cases per year (WHO, 2010), although data should be interpreted with caution. Good epidemiological studies consistently show that cases of plague are missed and that, conversely, during epidemics it is over-diagnosed. Plague has a very uneven distribution throughout the continent, and over time, with DRC, Madagascar, Tanzania, Uganda, Malawi, Mozambique and Algeria all reporting cases.

The importance of plague does not lie in the fact it is common (it is not), but that it is essential not to miss it when it occurs. This is for the sake of the individual, for health care workers caring for the patient, and for public health reasons. Plague, with its overtones of the Black Death decimating populations in major pandemics, has induced mass panic when potential outbreaks are announced. This panic, which has serious implications for public health, is partially justified. Untreated, even the mildest (bubonic) form has a mortality of over 50 per cent, and untreated pneumonic plague is almost 100 per cent fatal. The risk of infection is, however, very low.