Seasonal variations in nutrition among a group of nomadic pastoralists in Niger.

To identify the most critical period in a normal year for nomadic Sahelian pastoralists, 54 families of Wodaabe herders in Niger were visited every 3 months for a year. At each visit an average of 366 herders were interviewed with a standard questionnaire and anthropometric measurements were made. A cohort of 32 adult men lost a mean 3.1 kg between February and May, the peak of the dry season, and 30 adult women lost a mean 2.4 kg during the same period. Both men and women regained weight progressively over the months until the next February. Children under 5 years not only stopped gaining weight between February and May but on average lost 113 g; after May normal rates of weight gain resumed. This weight loss caused an increase in the proportion with acute malnutrition (less than 80% reference median weight-for-height) to 17% in May from 7% in November.