Even in ancient times, people living around the Mediterranean recognized that fava beans caused illness in certain persons. In the spring, when the fava plants blossomed, many historians noted young men felt tired and lethargic. This syndrome was so pronounced that it may explain why Pythagoras advised his followers to avoid consuming broad beans. In the nineteenth and early twentieth centuries, the disease was known as "Baghdad Fever."
Modern medicine first identified favism in the 1950s. During the Korean war, servicemen going overseas were given the anti-malarial drug primaquine. Nearly 15% of African-American soldiers and nearly as many of Italian or Greek descent developed acute anemia, resulting in many deaths of otherwise fit soldiers. Testing performed on prisoners at the Stateville Penitentiary in Joliet, Illinois determined that the problem was caused by a genetic enzyme deficiency and was, in fact, favism.
What Are the Symptoms of Favism?
People with favism experience acute hemolytic anemia when they are exposed to fava beans. Acute hemolytic anemia is the breakdown of red blood cells, which carry oxygen throughout the body. When these cells break down too rapidly, the bone marrow cannot replace them quickly enough and the body is unable to get enough oxygen.
Symptoms experienced by people with favism vary with the severity of the illness. Mild symptoms may include fatigue, headache, fever, nausea, stomach pain, and vomiting. Early signs of favism include dark orange urine (indicating the presence of blood in the urine), jaundice (yellow coloring of the skin), and feeling worn out over a long period of time. If favism is untreated, the person may slip into a coma and may require blood transfusions. In infants, young children, and very severe cases, favism can be fatal.
The amount of exposure to fava beans required to cause illness also depends on the severity of the individual's condition. The most common trigger is eating fava beans, but some people are so sensitive they react to the pollen of the plant or even to eating meat from an animal that consumed the beans. There are many cross-reactive agents as well, such as many types of broad beans and some medicines, including certain anti-malarial drugs and antibiotics. Many people with favism become ill when exposed to napthalene, the chemical in mothballs.
What Causes Favism?
Favism is an inherited condition linked to the X chromosome. Although females may suffer from the disease, they are more often carriers and males are much more likely to become sick with favism. The condition is most common in people of Mediterranean and North African descent, although people from other African regions, the Middle East, and South Asia are also at risk. People who inherit this condition to not have an enzyme called Glucose-6-Phosphate Dehydrongenase or G6PD. G6PD deficiency is the most common enzyme deficiency in the world, affecting over 400 million people.
Treatment of Favism
G6PD deficiency can be detected by a very simple blood test. In cases of identified favism, the most important treatment is avoidance of triggering foods and medicines. People with favism must also be sure to be vaccinated since infections can trigger an attack.
For acute attacks, blood transfusions may be necessary. Some people with chronic, severe reactions may benefit from a splenectomy (removal of the spleen) because much destruction of the red blood cells occurs in the spleen.
The Anti-Malarial Benefits of Favism
As strange as it seems, favism has a good side. The region around the Mediterranean is home to the mosquitoes that carry malaria, a potentially deadly disease. Even today, over 800 million people contract malaria every year and over 2 million of those die. Before the development of modern medicine and pesticides to reduce mosquito populations, the number would have been much higher. People with the genetic mutation that causes favism have an increased resistance to malaria, especially the most deadly form of malaria. The plasmodium that causes malaria infects the red blood cells. Since favism causes the breakdown of those cells, it also kills the plasmodium.
Because of the geographical overlap of malaria and favism, many scientists believe the genetic mutation that causes favism is an example of convergent evolution. In this case, the parasite, the protective mutation, and the regional culture have all adapted to provide the optimum situation for survival.
Although favism can be quite dangerous, even fatal, it is easily detected and can be treated. In addition, it likely prevents many deaths from malaria since it provides significant resistance to that disease.
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