More than 30 million children are unimmunized either because vaccines are unavailable, because health services are poorly provided or inaccessible, or because families are uninformed or misinformed about when and why to bring their children for immunization.Pneumonia, diarrhoea, malaria, measles, HIV/AIDS and malnutrition are the primary killers of children in the developing world. These children die because they are poor, they do not have access to routine immunization or health services, their diets lack sufficient vitamin A and other essential micronutrients, and they live in circumstances that allow pathogens (disease-causing organisms) to thrive.
The possibility that children will become seriously ill or die depends largely on whether their immune systems can fight off infections. Malnutrition, combined with unsanitary or crowded conditions, makes them extremely vulnerable. Measles, for instance, rarely kills in industrial countries but can cause up to 40 per cent mortality among infected children in dire and overcrowded situations which may occur following earthquakes, floods or when populations are displaced by conflict.
A variety of pathogens – bacteria, viruses and parasites – are responsible for the major childhood diseases. Bacteria causes tetanus, diphtheria, pertussis and tuberculosis. Viruses cause polio and measles. A single-celled parasite causes malaria.
Measles, a viral respiratory infection, killed over 500,000 children in 2003, more than any other vaccine-preventable disease. The measles death toll in Africa is so high – every minute one child dies – that many mothers don't give children real names until they have survived the disease. Measles weakens the immune system and renders children very susceptible to fatal complications from diarrhoea, pneumonia and malnutrition. Those that survive may suffer blindness, deafness or brain damage.
Tetanus, referred to in the Old Testament as the “seventh-day death,” killed an estimated 200,000 newborns and 30,000 mothers in 2001. The tetanus bacteria are ubiquitous – they live in soil, in animal dung and in feces. Tetanus can infect newborns if the umbilical cord is cut with unsterile instruments or the incision treated with contaminated dressings.
In acute respiratory infections such as diphtheria or pertussis, bacteria can attack the lungs or bronchial tubes, causing chronic coughs, pneumonia and breathing difficulties. Pertussis – also known as whooping cough – kills about 300,000 children a year, while a third respiratory infection, Haemophilus influenzae type b (Hib) pneumonia kills about 500,000.
“In cases like Afghanistan with a combination of conflict and prolonged drought, the coping mechanisms of children have dwindled. They are malnourished; they suffer from a variety of illnesses. If they have a bout of measles, the fatality rates will be high.” – Deputy Director, UNICEF Supply Division, Shamsul Farooq, former Senior Programme Officer in the Humanitarian Response Unit.
Polio, a viral infection of the nervous system, can cause crippling paralysis within hours. Significant progress has been made towards eradicating the disease, but it remains a serious threat to children in areas where the wild poliovirus still circulates. The number of cases worldwide dropped from 350,000 in 1988 to under 1,300 in 2004.
Haemophilus influenzae type b (Hib), prevalent mainly in developing countries, is estimated to cause approximately 3 million cases of serious disease and kills about 450,000 children every year. Most children die from pneumonia and a minority from meningitis. In developing countries about 40% of Hib meningitis cases are fatal, and 15-35% of children who survive are left with permanent disabilities. Despite gradual uptake of the Hib vaccine in developing countries, in 2001, only one in five children worldwide were immunized against Hib during the first year of life.
Rotavirus, a pervasive wheel-shaped virus, is a leading cause of severe diarrhoea in infants and young children, particularly in the developing world. Currently, there is no vaccine approved for the disease, which kills 600,000 children under five each year.
Hepatitis B virus infects many infants and children – more than 2 billion people have been infected with the virus at some point, and an estimated 350 million are lifelong carriers. However, most don't develop the clinical disease until several decades later when the virus can cause inflammation of the liver and lead to cirrhosis or liver cancer.
Yellow fever, a viral disease that occurs primarily in tropical and subtropical areas of Africa and South America, kills 30,000 each year. The virus is transmitted most often through the bite of the female Aedes aegypti mosquito. Once controlled fairly well by widespread vaccination and mosquito control, the disease is making a comeback and outbreaks are becoming more frequent.
The parasitic disease malaria is responsible for a staggering number of deaths - over one million a year - the majority children under five. A child dies every 30 seconds from malaria, many in just days after infection. Pregnant women infected with malaria can give birth to underweight babies who are then vulnerable to other diseases.
Today, 90 per cent of malaria cases occur in sub-Saharan Africa. Malaria, so named by the Romans because they believed it arose from bad (mala) air (aire) floating up from nearby swamps, is in fact caused by a single-celled parasite, Plasmodium, which is transmitted by the bite of the Anopheles mosquito. Though there is no vaccine for malaria, it can be controlled with mosquito nets and insect repellant, and is often treatable with antimalarial drugs.