Poverty and the scarcity of adequate health services have combined to make disease a particularly severe problem throughout Africa. Africans have to deal with many of the same illnesses that affect people in other parts of the world. They suffer from infectious diseases such as measles, lifestyle-related illnesses such as cancer and heart disease, and sexually transmitted diseases (STDs). However, social and economic conditions in Africa make the treatment and prevention of these diseases more of a problem than in wealthier, more industrialized nations. Moreover, certain diseases exist only in Africa, and various factors such as climate and traditional ways of living make it especially difficult to keep them under control.
Africa is home to a wide variety of infectious diseases caused by viruses or parasites that live in monkeys, rats, or other animals known as hosts. Flies, mosquitoes, and other agents known as vectors transmit the diseases to humans.
Africa has some infectious diseases that appear nowhere else in the world and appears to be the source of numerous diseases found on other continents. Over the centuries, these diseases were spread through trade and travel. The SLAVE TRADE, for example, brought various African diseases to the Americas.
In modern times, the ease of travel has allowed infected people and livestock to carry additional viruses and parasites from Africa to other parts of the world. Mosquitoes and other animals that act as disease vectors have also found their way to other continents by way of airplanes and ships.
Parasitic Diseases Limited to Africa
One of the most common parasitic diseases in Africa is trypanosomiasis, or sleeping sickness. Often fatal, sleeping sickness is caused by a single-celled microorganism that lives in wild animals and is transmitted to humans and cattle by the bite of the tsetse fly.
Treatment with drugs can cure most cases of sleeping sickness, and the spread of the disease can be controlled by eliminating tsetse flies near populated areas. However, sleeping sickness remains a serious problem in rural areas and in nature preserves protected from human settlement. Sleeping sickness is found mostly in Africa's savanna regions, which are home to the game animals that carry it. Although a serious problem for humans and domestic animals, the disease has helped preserve wildlife herds in Africa by discouraging the expansion of human settlement in the savanna. It has also played a role in controlling the spread of the desert into savanna areas by limiting the livestock herds that graze on grasslands. Leishmaniasis, another African parasitic disease, causes sores and disfigurement of the face. Some forms of the disease are found in South America and Asia, but one variety appears only in Africa. A common host animal for the disease is the hyrax, a cave-dwelling rodentlike animal. Sand flies feed on the blood of the hyrax and transmit the disease to humans.
Several parasitic diseases are transmitted by worms. The loa loa worm carries a disease called loaisis that causes swelling of the skin and allergic reactions. The small worm enters the bloodstream of humans through bites from a type of large horsefly. It can often be seen crossing under the thin membrane that lines the inner surface of the eyelid in an infected person.
Parasitic Diseases of African Origin
A number of parasitic diseases found around the world originated in Africa. Perhaps the most widespread of these is malaria, now also a major health problem in Asia and South America.
The parasites that cause malaria, a disease characterized by recurring cycles of severe chills, fever, and sweating, are carried by Anopheles mosquitoes. Each year more than a million children—mostly in Africa—die from malaria. It is the leading cause of death among African children. Most adults who live in areas of Africa where malaria is common have developed a great deal of natural immunity, or resistance, to the disease. Vaccines to prevent malaria exist but are not widely available to Africans. The vaccines may also damage naturally acquired immunity. Various drugs are used to treat malaria, but the malaria parasites have developed resistance to some of them. Most efforts to prevent malaria focus on eliminating mosquito-breeding areas and using mosquito netting to protect potential victims.
Parasites that live in small water-dwelling snails cause a disease called schistosomiasis, or bilharziasis. Once confined to central Africa, the disease was spread to the Americas by the slave trade and now occurs in many places that lack piped water supplies or that rely heavily on irrigation. Humans become infected by bathing, washing, or working in water containing the snails and their parasites.
Health experts estimate that schistosomiasis affects 200 million people worldwide, most of whom live in Africa. A single dose of a drug called praziquantel can cure schistosomiasis, and the snails can be killed with chemicals. The best long-term solution, however, is providing safe water supplies and educating people about how to avoid exposure to the parasites.
One of the most serious parasitic diseases in Africa is onchocerciasis, or river blindness, which is caused by a certain species of worm. The worms are carried by blackflies that breed in rivers and streams of rain forests. River blindness causes severe disfigurement of facial skin and often leads to permanent blindness. Over 30 million Africans suffer from river blindness, and in some areas about one third of the adult population has been blinded by the disease.
River blindness came to the Americas with the slave trade and is now widespread in Central America and South America. A drug called ivermectin provides an effective treatment for the disease, but eliminating breeding areas for the mosquitoes that carry the disease has dramatically reduced infection rates in many areas of Africa.
Viral Diseases Limited to Africa
Lassa fever, which is carried by rats, is found mainly in West Africa. This viral disease causes fever, bleeding, swollen face and neck, and liver failure. The rats that carry lassa fever live in thatched-roof huts in rural areas, making it difficult to control the spread of the disease. Researchers are currently working on a vaccine.
Two of the most frightening viruses in Africa are the Marburg virus and the Ebola virus. The Marburg virus causes an extremely serious, often fatal disease characterized by severe internal bleeding. Little is known about the source of infection, but it seems to be transmitted by direct contact with an infected person.
Similar to the Marburg virus, the Ebola virus also causes severe internal bleeding and is usually fatal. It is spread by contact with the blood of an infected person, by infected needles, and through sexual contact. The host animal for the virus has not been identified, but bats are suspected.
So far there have been only occasional outbreaks of Marburg and Ebola in Africa, but experts fear the possibility of epidemics in the future. There is no vaccine or known treatment for either virus, and the only way to stop their spread is by keeping infected individuals in quarantine.
Viral Diseases of African Origin
Although first identified in Cuba, Central America, and the United States, yellow fever originated in Africa, where the hosts are tree-dwelling monkeys. Mosquitoes in forested areas transmit the virus to humans, who bring the disease back to populated areas. There it is spread by Aedes aegypti, a common species of mosquito. Yellow fever causes a yellowish discoloration of the skin, internal bleeding, and vomiting. A highly effective vaccine is available that gives lifelong protection against yellow fever, and control of the disease is also achieved by eliminating mosquito habitats.
The viral disease AIDS was identified in the United States in 1981. However, research has shown that the first human cases occurred in central Africa at least as early as 1959. Researchers believe that HIV, the virus that causes AIDS, originated in African monkeys or apes. Among human populations, HIV is spread by sexual intercourse or contact with contaminated blood. Mothers can also pass HIV to unborn children during pregnancy or while breast-feeding their infants.
In most cases it takes a number of years for HIV to develop into AIDS. As it progresses, AIDS destroys the human immune system, which normally protects the body against infectious disease. Death is often caused by secondary infections that occur after the breakdown of the victim's immune system. Drug treatments have helped prolong the lives of some people with AIDS, but a cure for the disease has not yet been found.
In the early years, African officials paid little attention to AIDS, but the seriousness of the problem soon became evident. The number of cases of AIDS in Africa has skyrocketed, with infection rates in some major cities in central and eastern Africa reaching 25 percent of sexually active adults. Because of the high death rate, the absence of an affordable and effective treatment, traditional sexual practices, and the lack of effective health education, AIDS threatens to be a devastating public health problem in many parts of Africa in the coming years.
DISEASES WITH SPECIAL FEATURES IN AFRICA
A number of diseases that exist within and outside of Africa occur in somewhat different forms or circumstances in Africa. These differences can be traced mostly to factors such as climate, geography, and the behavior and customs of people likely to be affected by the disease.
During the 1960s measles was the leading cause of death among West African infants. Widespread malnutrition contributed to the development of pneumonia, diarrhea, and other secondary infections in children with measles. Other complications from measles led to blindness, deafness, and mental retardation. Vaccines now available have helped reduce the danger from measles in urban areas, but the disease is still a major problem in remote areas.
Meningitis is another viral disease that has been much more devastating in Africa than in the West. At one time, periodic epidemics of the disease killed as many as 15,000 people. Antibiotic drugs have been effective in controlling meningitis, but parts of Africa—particularly the northern savanna region stretching from BURKINA FASO to SUDAN—still experience epidemics from time to time.
Two common infectious diseases related to animals, hydatid disease and trichinosis, also have special characteristics in Africa. Hydatid disease is caused by a worm that lives in dogs and is transmitted through their bodily waste. It is most common in the Turkana region of KENYA, where working mothers often use dogs to look after their children, than anywhere else in the world. Hydatid produces large growths in the liver that can be treated either with surgery or drugs.
Trichinosis, caused by eating tainted meat from pigs, attacks muscle tissue, including the heart, and can cause heart failure. In Africa, trichinosis infects wild pigs, but not domestic pigs. Taboos against eating wild pigs have helped to control the spread of the disease.
Sexually transmitted diseases (STDs), such as syphilis and gonorrhea are widespread in Africa. Lifestyle and attitudes toward GENDER ROLES AND SEXUALITY play a major role in this problem as does the high proportion of young people in Africa. A significant part of the population falls in age groups most affected by STDs—men 20 to 30 years of age and women 15 to 25. Moreover, African men tend to marry later than men in the West. In the meantime, they may have sex with prostitutes who may carry STDs. In addition, many men move to urban areas to find work, and when they return home they may bring STDs back to their wives. Many men are also reluctant to use condoms.
With few doctors and little access to health care, education about and treatment of STDs in Africa lags far behind the West. As with other diseases, Africa's poverty contributes both to the development and spread of STDs and to the difficulty of preventing and curing the diseases.
The leading cause of death in industrialized countries is coronary heart disease, caused by a high-fat diet, lack of exercise, and cigarette smoking. In Africa heart disease is almost unknown, even among people who have a high-fat diet. But rheumatic heart disease, which is now rare in the West, is the most common cause of heart failure in Africa. One reason may be that rheumatic heart disease is associated with poverty and a certain type of bacterial infection—both widespread in Africa.
Cancer occurs in Africa as well as in the West, but the most common types are different. Lung cancer, for example, has been rare in Africa, though it is on the rise now as more Africans are smoking. Another type of cancer found more frequently in the West than in Africa is prostate cancer, which affects only men. The low incidence of this disease in Africa may be related to diet. However, cervical cancer is more common in Africa than in Western countries. The high rate of this type of cancer, which affects women, seems to be associated with early sexual activity and multiple pregnancies. Another type of cancer that is common in the West but almost nonexistent in Africa is skin cancer caused by too much exposure to the sun. In Africa, solar cancers are almost unheard of because there are built-in protective mechanisms in African's pigmented skin. Scientists learn a great deal about tumors by studying the factors that make some cancers common in Africa, but not in the West. (See also AIDS, Healing and Medicine, Health Care, Pests and Pest Control.)