The relatively high prevalence of IDDM in this poor African population, despite potential deaths caused by minimal medical attention, may be because of long-term protein malnutrition and endemic childhood infections, which have been implicated in the etiology of IDDM in similar malnourished populations.

According to month of diagnosis, 165 children who developed Type 1 (insulin-dependent) diabetes mellitus at the age of 0-16.2 years (mean +/- SD, 7.6 +/- 4.1 years) could be divided into 69 patients diagnosed during peak seasons (epidemic cases) and 96 patients diagnosed during months of low incidence (non-epidemic cases). Seasonality of onset of symptoms and of diagnosis was observed in both sexes in all age groups. The patients diagnosed during peak seasons had shorter duration of symptoms (13.2 +/- 8.1 days) as compared to 22.9 +/- 10.3 days; p less than 0.001 in the patients diagnosed during months of low incidence. At diagnosis, 88.4% (61/69) of the epidemic group had ketonuria as compared to 71.9% (69/96); p less than 0.06 in the non-epidemic patients. The values of C-peptide, insulin antibodies, haemoglobin A1c and HLA-DR phenotype frequencies in the 69 epidemic patients were compared with those of the 96 non-epidemic patients. In the epidemic patients, the C-peptide values of 0.11 +/- 0.05 mmol/l at diagnosis had increased to 0.12 +/- 0.05 mmol/l at one month and 0.13 +/- 0.06 mmol/l at 3 months. These values were significantly lower (p less than 0.001) than in the non-epidemic patients at the same time points: 0.17 +/- 0.08 nmol/l; p less than 0.001, 0.23 +/- 0.11 nmol/l; p less than 0.001, and 0.22 +/- 0.10 nmol/l.(ABSTRACT TRUNCATED AT 250 WORDS)

Subpopulations of T and B lymphocytes and levels of serum immunoglobulins G, A, M, E and subclasses G1, G2 and G3 were studied in 45 healthy school children aged 8-16 years during four seasons of the year. There were significant increases in CD4+ T helper cells, total T lymphocytes and CD4+/CD8+ (helper/cytotoxic) T-cell ratio during the spring season. While the levels of CD8+ T cells and total B lymphocytes remained statistically unchanged during all four seasons, the levels of natural (HNK-1) killer cells and macrophages increased significantly during the autumn and summer seasons respectively. The levels of immunoglobulins G, A, M and E remained statistically unchanged during all four seasons. Girls had higher levels of CD4+ T cells and a higher CD4+/CD8+ T-cell ratio than boys. Girls also had slightly higher levels of immunoglobulin G and M. These observations suggest that seasonal variations of some immunological parameters occur in healthy children. This may be an adaptive response to variable climatic and other environmental factors. These natural variations due to seasonal changes should be taken into account when immunological tests are used in clinical investigations.