The World Health Organization (WHO) planned to study the relationship between the eating habits of the people and the disease. Two doctors were chosen to make the study. They flew to Africa south of the Sahara and during the next two months visited ten countries. They found that serious diseases of poor eating, often mistaken for other diseases, existed in all parts of Africa. The diseases were similar and could therefore all be named kwashiorkor. The diseased children are usually from one to four years old. As the illness progresses, the child's stomach becomes swollen by liquid collecting in the body. The skin changes color and may break out in open sores . The hair changes color and starts to fall out. The patient loses all interest in his surroundings and even in food, and becomes so weak that he wants to lie down all the time. Stomach liquids are no longer produced. The doctors reasoned that kwashiorkor was found in the young children of this age in many parts of Africa because of lack of milk or meat. Their mothers, after stopping their breastfeeding, gave them foods full of starches instead of greatly needed proteins. They found that the addition of milk to the food of the children suffering from kwashiorkor saved many lives. The unbelievable thing about kwashiorkor is that the very existence of the disease--which has been killing thousands of children for centuries--was not even recognized in Latin America as recently as ten years ago. The deaths of those children were mistakenly listed as due to other diseases. It was the WHO's work in Africa that led to the discovery of the problem in Central America. It is difficult to discover kwashiorkor because   _   .
it has no symptoms at all it is hard to identify signs of it it doesn't last long enough for careful observation it is hardly different from other diseases