Nature and nurture in the disease patterns of Africa. The twentieth Maude Abbott lecture
Hutt, M.S.
Pathology Annual 13 Pt 1: 19-27
1978
ISSN/ISBN: 0079-0184 PMID: 364383 Document Number: 4366
The evidence presented suggests that these three dissimilar conditions, BL, TSS, and EMF, are epidemiologically linked with areas where there is high transmission of Plasmodium falciparum malaria. In BL, and more speculatively, in EMF, the effect is to produce an immunologically susceptible host who reacts in an unusual way to some other causative agent, whereas in TSS no other environmental agent appears to be necessary. The importance of nature (genetic factors) is, however, also clearly shown by the protective effect of the sickle cell trait against malaria, which explains the low frequency of this trait both in BL and in TSS. The explanation of the altered immunologic response in Rwandans is still not clear, though it has been known for many years that individuals who have lived in nonmalarious areas are less able to mount a specific immune response to malaria than those from malarious areas. This phenomenon may be due to differences in immune recognition genotypes closely linked with the major histocompatability complex. The fallacy of the either/or approach to the nature/nurture explanation of disease is increasingly apparent. As Sir Gavin de Beer wrote, "It is now recognized that no character owes its existence to inheritance alone or to environment alone. No character is either innate or acquired; all are both, but in varying degree because the degree of penetrance that genes show can be very variable." Although oversimplified views of the etiologies of the three diseases have been presented, I think that they serve as valid illustrations of the interactions of nature and nurture. These studies should also remind us that though we increasingly look to molecular biology and ultrastructural studies to solve our problems, we must never forget the study of populations of people in their immense genetic and environmental diversity.
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