India is the second most populous country in the world (844 million, in the 1991 census). 8% of the total population (67.52 million) are Tribals. They are considered to be the aboriginal people of India on the basis of their anthropological characteristics. They differ not only from the surrounding non-aboriginal Indian populations (who are called the Caste populations), but also from one another in dialect, race, socio-economic and cultural patterns.
There are 427 Tribal groups in India (census of India 1971). Tribal groups in the Southern, Central and Eastern regions are Proto-Australoids, in the North Eastern region (Assam) are Mongoloids and in the Himalayan region are Caucasoids (Malhotra 1978). Tribals reside in hilly and forest areas where the means of communication are very difficult. There is hardly any communication between Tribals and Urban population (especially in Central India) and they still believe in magic, witch-craft etc. Some of the Tribal communities are still at the hunting-gathering and pre-agricultural level of technology. In 1935 the Government of India passed a Forest Act forbidding them to exploit the forest in order to preserve the wild animals and forest produce, instead the Tribals were allocated a restricted amount of land for agriculture. This led to Tribal unrest and great difficulty for their livelihood.
Literacy is very low (9%, census of India 1971). In Madhya Pradesh the total Tribal literacy is 10.68%; 17.7% in males and 3.6% in females. Inbreeding in Tribals is high due to their strictly endogamic behaviour (preferring marriage within the family and always within the Tribe).
Haemoglobin disorders are common in India, particularly among the Tribals. In North Eastern India haemoglobin E is common. Sickle haemoglobin (trait) is found from 0-31% in Central India, 0-43% in South Indian, 0-33% in Western Indian and 0-14% in Eastern Indian Tribes. β-thalassaemia has been found in some Central Indian Tribes like Bhil, Bhilala and Pateli, North Eastern Tribes viz Santhal and Bhumij and also in some Western Indian Tribes. α-thalassaemia is common in Central, Eastern, Western and Southern Indian Tribes. Glucose 6 Phosphate Dehydrogenase deficiency is also common and may be a health problem. Its prevalence in males in North Eastern India ranges from 0-27%, in Central India from 0-16.03%, in Western India from 0-10.58% and in Southern India from 0-13.0%.
Iron deficiency is to be expected in all Indian Tribal groups due to their poor intake of nutrients. Most of the Central Indian Tribals rely mainly on ‘Pej’ (a kind of gruel made of boiling the millets or rice in large quantities of water), this leads to protein and iron deficiency. A high incidence of helminthic infestation also contributes significantly to this problem.
Tribals of India (especially central India) have a severe problem with drinking water. They prefer to drink water from nullahs (small brooks) which are polluted and transmit water born diseases like cholera, diarrhoea etc. Lack of sufficient iodine in drinking water often leads to Goitre. Infectious diseases like tuberculosis and scabies are common. The prevalence of malaria (including chloroquine resistant malaria) is very high since the area is hilly and forested creating congenial conditions for mosquitoes to breed. Means of transport are meagre and many areas are totally cut off from the main stream during the rainy season.
Medical care is inadequate in most Tribal areas. Lack of proper immunization leads to Polio and other diseases. Tribals do not believe that they can control birth and death. They do not have faith in modern allopathic medicine and prefer their own traditional herbal medicine. To overcome these problems, an improved understanding about Tribals and possible means of educating them is needed. Efforts from all angles – local Medical personnel, Social workers, the community itself and local government officials – are required.
A research study is being carried out by us to study the hereditary anaemias (abnormal haemoglobins, thalassaemias and G6PD deficiency), consanguinity and kinship patterns in the Baiga, "a Central Indian Tribe", with financial support from the Marie Stopes Research Fund. Our preliminary results showed a high prevalence of sickle haemoglobin trait (17.73%) and α-thalassaemia & iron deficiency. G6PD deficiency in males is found to be 5% and parents were consanguineous in 32.47% of couples in Baiga Tribe. It will be interesting to study the reproductive behaviour of families with sickle haemoglobin and G6PD deficiency versus normals and consanguineous versus non consanguineous. It will be useful to know, to what extent sickle haemoglobin and con sanguinity contribute to mortality in an isolated population. The present work will be continued to study all these factors in the near future.
How can sickle haemoglobin remain so common in a population which is practising inbreeding for so many generations? To what extent does natural selection due to malaria contribute to the high frequency of sickle haemoglobin? When did malaria and sickle haemoglobin originate in this area? Is practice of consanguinity really harmful in such conditions?
P. Hemachandra Reddy
Bernadette Modell
Perinatal Centre
86-96 Chenies Mews
University College Hospital
London WC1E 6H