The 2001 meningitis epidemic in south Chad.

AIM: Bacterial meningitis is widespread in many areas of tropical countries, has a high mortality rate, and is often devastating. However, epidemiological studies in rural areas are quite rare, especially in Chad. We report data concerning the 2001 meningitis epidemic in the Moyen Chari district, in Southern Chad. METHODS: Five-hundred and ninety-five cases of meningitis were admitted in hospital from January to April 2001. Diagnosis was made on the basis of clinical presentation and/or by cerebrospinal fluid (CSF) specimen analysis. Antimicrobial treatment, time of recovery or death were recorded. Treatments most employed were oily chloramphenicol (CAP) and ampicillin, alone or combined. RESULTS: Two peaks of incidence have been observed: one in children aged below 1 year and the other in 6 year-olds with an overall lethality rate of 8.74%, particularly in children aged below 2 years. Incidence decreased over 13 years of age. Weekly incidence per 1 000 inhabitants, ranged from 0.21 to 1.69. Microbiological data indicated S. pneumoniae as the leading pathogen, but the epidemic nature of the disease suggests that this pathogen was probably overestimated. CONCLUSION: Our data suggest that an incidence of 10 cases per 100 000 appears most useful in predicting an epidemic. CAP was significantly the most effective treatment in terms of lethality, need for second-line treatment, and mean hospital stay, particularly if first administered at a primary health center. In case of lack of response to CAP treatment, the association of ampicillin and gentamicin seems more advisable than ampicillin alone.

Habitat specialization and adaptive phenotypic divergence of anuran populations.

We tested for adaptive population structure in the frog Rana temporaria by rearing tadpoles from 23 populations in a common garden experiment, with and without larval dragonfly predators. The goal was to compare tadpole phenotypes with the habitats of their source ponds. The choice of traits and habitat variables was guided by prior information about phenotypic function. There were large differences among populations in life history, behaviour, morphological shape, and the predator-induced plasticities in most of these. Body size and behaviour were correlated with predation risk in the source pond, in agreement with adaptive population divergence. Tadpoles from large sunny ponds were morphologically distinct from those inhabiting small woodland ponds, although here an adaptive explanation was unclear. There was no evidence that plasticity evolves in populations exposed to more variable environments. Much among-population variation in phenotype and plasticity was not associated with habitat, perhaps reflecting rapid changes in wetland habitats.