Chapter 3 of 16
Infectious diseases are among the biggest disablers
Graphs: Burden of disease
Initiative: Rolling back malaria
|The high death toll
from infectious diseases is only part of the story. The scale of individual pain and
suffering inflicted by these diseases is immense. At any one time, hundreds of millions
of people - mainly in developing countries - are disabled by infectious diseases.
Some infectious diseases can cause sudden repeated bouts of debilitating illness throughout the year - keeping children away from school and preventing adults from working or caring for their children.
Other diseases result in severe deformities - covering the body with gaping sores, mutilating the facial features, causing the loss of fingers and toes and leading to withering or grotesque swellings of the limbs and other body parts. Those affected not only suffer from excruciating pain and severe handicap but are also victims of stigmatization, shame and anguish.
Meanwhile, the economic impact of repeated episodes of illness and long-term disability is a major cause of underdevelopment in many countries today. The economic burden of malaria alone has cost Africa billions of dollars this decade. In addition to the cost of lost working days, the cost of treatment for repeated bouts of malaria can also be a huge burden for the poorest families. In Nigeria, it has been estimated that subsistence farmers spend as much as 13% of total household expenditure on malaria treatment.
Lymphatic filariasis is second only to mental illness as the world's leading cause of long-term disability. A mosquito-borne disease involving infection with parasitic worms, it can cause grotesque enlargement of the limbs and genitals and damage to internal organs. It affects about 120 million people. At least one billion people are at risk - one in six of the world's population. Over 40 million people are severely disfigured and disabled by filariasis. In addition, the social and psychological impact can be enormous - often destroying marriages and family relationships.
Another widespread parasitic worm disease, schistosomiasis, causes chronic urinary tract disease and often results in cirrhosis of the liver and bladder cancer. Over 200 million people are infected worldwide and up to three times as many are at risk. This debilitating disease is spread by water snails and contracted through contact with stagnant water sources. It can spread to new areas through dam-building and irrigation projects. Children and rural workers are most at risk and the disease can cause high absenteeism at school and work. In some of the worst-affected areas over 90% of children can be affected simply as a result of wading through water.
More than 12 million people are infected with leishmaniasis, another insect-borne parasitic disease. The disease can cause internal organ damage, skin lesions and mutilation of the nose and mouth. People disfigured by the disease often have to endure rejection by their families as well. Today there is alarm at the sharp increase in cases of visceral leishmaniasis - a deadly form of the disease - due to emerging co-infections with HIV and an upsurge in epidemics in countries such as India and Sudan.
In addition, millions of people are incapacitated by infectious diseases which cause blindness. An estimated 5.6 million people today have been blinded or visually disabled by trachoma and an additional 154 million are infected - mainly in Africa and Asia. The disease is transmitted through person-to-person contact due to poor hygiene. In addition, over 85 million people in Africa, Latin America, and the Arabian Peninsula are threatened by onchocerciasis (river blindness). This parasitic disease, transmitted by blackflies, causes visual impairment, blindness, unbearable itching and skin lesions. The itching can be so intense that people scratch themselves with knives or stones to stop it. Some have even been driven to suicide.
In sub-Saharan Africa, sleeping sickness threatens 55 million people in 36 countries. A parasitic disease transmitted by the tsetse fly, sleeping sickness causes long-term debilitating illness and mental suffering. Without treatment, the disease is fatal. In the worst-affected countries over half the people in some villages become ill. In some provinces the disease is reported to have claimed more lives than AIDS.
Leprosy - one of the oldest scourges known to humanity - is still a problem in many countries in South-East Asia, Africa, and Latin America. Over half a million cases occur every year. About two million people are currently disabled by leprosy, which can cause severe mutilation of the face and extremities as well as damage to bones, eyes, nerves, and internal organs. Although the disease is not highly contagious, even today leprosy sufferers can become social outcasts.
Guinea-worm disease (dracunculiasis) is a parasitic disease transmitted by a tiny crustacean. During 1998, there were almost 72 000 cases of guinea-worm disease in Africa. The countries worst affected today are Ghana, Nigeria and Sudan. This debilitating disease causes joint pain, fever and vomiting. When the mature guinea-worm slowly emerges through the skin - by then up to a metre long - it causes excruciating pain and frequent infections at the exit point. The disability prevents people from going to work or school.
In Latin America, up to 18 million people are infected with Chagas disease, a deadly parasitic disease transmitted by blood-sucking insects. The disease can also be transmitted through blood transfusions and from mother to baby. The chronic stage of the disease can last for years as parasites invade the internal organs - causing irreversible damage to the heart and intestines. The disease is very difficult to treat with existing drugs. In some parts of Latin America it is the leading cause of cardiac death in young adults. One hundred million people are at risk. In Santa Cruz, Bolivia, over 50% of the blood in blood banks was infected with the parasites.
In 1995, four Sexually transmitted infections (STIs) - gonorrhoea, chlamydia, syphilis, and trichomonas - accounted for an estimated 333 million new cases of curable STIs. These four infections and their complications are among the top ten causes of disease burden.
|© World Health Organization 1999|