Sickle cell disease in Wayanad, Kerala: gene frequencies and disease characteristics

A large number of patients with sickle cell anaemia are seen at the Medical College, Calicut from among the tribals and Chetti communities of the adjacent Wayanad district. We carried out a population-based study of gene frequencies and disease characteristics to plan an appropriate intervention.

Clinical examination and haemoglobin electrophoresis were done in 1016 subjects belonging to the tribal and Chetti communities in Wayanad district, by visiting hamlets and schools and evaluating everyone present at the time of the visit.

The gene frequency of haemoglobin S ranged from 0.019 in Kattunayakan to 0.196 in Wayanadan Chettis. Wayanadan Chettis, Kurumas and Adiyas showed a high number of homozygotes with the oldest being 48 years. The survival of homozygotes is longer than what is generally recorded in other states. The disease was mild in 52.2% of cases. Painful crises were found in 43.5% and splenomegaly and leg ulcers in 4.3% each. The mean haemoglobin F rate in homozygotes was 25.9%. It was higher in clinically mild cases and in those showing an absence of irreversible sickle cells in the peripheral smear.

The survival of patients with sickle cell anaemia seems to be higher in Kerala as compared to other states. It appears that even small improvements in primary health care available to the population (as in Kerala) are sufficient to achieve this effect. Integration of disease diagnosis and management into the already existing health care delivery system may lead to even better survival and quality of life.