The 2001-03 Famine and the Dynamics of HIV in Malawi: A Natural Experiment

..At rural sites, the change in HIV prevalence was positively and non-linearly related to the extent of rural hunger, consistent with contemporary accounts of increased transactional sex and with hunger compromising immune function. At non-rural sites, prevalence declined as rural hunger increased (P = 0.006), concentrated in women who self-identified as farmers. This finding is consistent with contemporary accounts of migration in search of food and work from villages where HIV risk was lower to towns and cities where it was higher. Corroborating this interpretation, the proportion of farmers in the antenatal population was found to rise at non-rural sites as rural hunger increased in the surrounding district (P = 0.015) whereas the proportion fell with increasing rural hunger at rural sites. The models suggest migrants were predominantly farming women under 25 years. The household survey confirmed that there was a surge of rural-to-urban migration during the famine, particularly by women under 25 years. Migration to less affected rural areas also increased.

The Malawi famine appears to have had a substantial effect on HIV's dynamics and demography. Poverty and inequality, commonly considered structural determinants of HIV epidemics, can change rapidly, apparently transmitting their effects with little lag. Epidemic patterns risk being misread if such social and economic change is ignored. Many studies examining HIV prevalence declines have implicated sexual behaviour change but do not appear to have adequately considered the contribution of rural-urban migration. The evidence from Malawi, which links actions that undermined people's food security to changes in the prevalence and distribution of HIV infections, suggests new opportunities for prevention.

Below:  Prevalence of HIV in women attending antenatal clinics in Malawi 1994–2005.

Unweighted means. The number of sites was constant over this period. Data courtesy Malawi National AIDS Commission.

Below: Change in HIV prevalence at antenatal sites through the famine in relation to rural hunger.

The independent variable is the proportion of rural households estimated from a humanitarian survey to be in need of food assistance in December 2002—March 2003 in the district surrounding antenatal sites. The observed values of the dependent variable are the ratio of the HIV prevalence in women attending antenatal clinics in 2003, after the worst of the famine, to the prevalence in 1999/2000, prior to the rapid rise in food prices. The fitted values are from multilevel log binomial regression (model 1, Table 2). (A) Rural sites. The quadratic equation has a vertex at approximately 25%, implying little change in HIV around this level of hunger. (B) Non-rural sites (squares: cities, triangles: towns, open triangle: Nsanje, which is included in the analysis).

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By: Loevinsohn M1.

• 1Institute of Development Studies at the University of Sussex, Brighton, United Kingdom.