Anaemia is common throughout the world. Its main cause, iron deficiency, is the most prevalent nutritional deficiency in the world. Several infections related to hygiene, sanitation, safe water and water management are significant contributors to anaemia in addition to iron deficiency. These include malaria, schistosomiasis and hookworm.
The disease and how it affects people
Anaemia is a condition that occurs when the red blood cells do not carry enough oxygen to the tissues of the body. Anaemia affects all population groups. However the most susceptible groups are pregnant women and young children. In the milder form, anaemia is “silent”, without symptoms. In the more severe form, anaemia is associated with fatigue, weakness, dizziness and drowsiness. The signs include loss of normal colour in the skin (in fair skinned people) and also in the lips, tongue nail beds and the blood vessels in the white of the eye. Without treatment, anaemia can worsen and become an underlying cause of chronic ill health, such as impaired fetal development during pregnancy, delayed cognitive development and increased risk of infection in young children, and reduced physical capacity in all people. Low birth weight infants, young children and women of childbearing age are particularly at risk of anaemia. Women of childbearing age need to absorb 2-3 times the amount of iron required by men or older women.
The main causes of anaemia are nutritional and infectious. They usually coexist in the same individual and make anaemia worst.
Among the nutrition factors contributing to anaemia, the most common one is iron deficiency. It is due to a diet that is monotonous, but rich in substances (phytates) inhibiting iron absorption so that dietary iron cannot be utilised by the body. Iron deficiency may also be aggravated by poor nutritional status, especially when it is associated with deficiencies in folic acid, vitamin A or B12, as is often the case in populations living in developing countries
With regard to infections, malaria is another major cause of anaemia : it affects 300-500 million people, and in endemic areas it may be the primary cause of half of all severe anaemia cases (WHO, 2000). Hookworm infection and in some places schistosomiasis also contribute to anaemia. Approximately 44 million pregnant women have hookworm infections and 20 million people are severely infected with schistosomiasis. Anaemia can also be due to excessive blood loss, such as gastrointestinal infections associated with diarrhoea. The most important water-related causes of anaemia are malnutrition and water-borne or water-related infections.
Anaemia is a common problem throughout the world and iron deficiency is the most prevalent nutritional deficiency in the world. It affects mainly the poorest segment of the population, particularly where malnutrition is predominant and the population exposed to a high risk of water-related infection.
Scope of the problem
Nine out of ten anaemia sufferers live in developing countries, about 2 billion people suffer from anaemia and an even larger number of people present iron deficiency (WHO, 2000). Anaemia may contribute to up to 20% of maternal deaths.
Full discussion of strategies towards anaemia prevention are beyond the scope of this Fact Sheet. Because anaemia is the result of multiple factors, the identification of these factors and of the causes and type of anaemia is important. Important actions include addressing underlying causes correcting iron deficiency, treatment of underlying disease processes (in particular nutritional deficiencies - Folic acid, Vitamin A and B12).
In children, promoting breastfeeding and proper complementary foods are important in controlling anaemia.
Improving hygiene, sanitation and water supply; and improving water resource management to contribute to control of schistosomiasis and malaria where they occur are important contributory measures in prevention of anaemia.
WHO. Turning the tide of malnutrition: responding to the challenge of the 21st century. Geneva: WHO, 2000 (WHO/NHD.007)
Prepared for World Water Day 2001. Reviewed by staff and experts in the Department of Nutrition for Health and Development (NHD) and the Water, Sanitation and Health Unit (WSH), World Health Organization (WHO), Geneva.