Protection against Diarrhea Associated with Giardia intestinalis Is Lost with Multi-Nutrient Supplementation: A Study in Tanzanian Children

Giardia intestinalis is a well-known cause of diarrhea in industrialized countries. In children in developing countries, asymptomatic infections are common and their role as cause of diarrhea has been questioned. In a cohort of rural Tanzanian pre-school children, we assessed the association between the presence of Giardia at baseline and subsequent diarrhea risk. The study was conducted in the context of a randomised trial assessing the effect of supplementation with zinc and other micro-nutrients on malaria, and half of the children daily received a multi-nutrient supplement. Surprisingly, we found that the presence of Giardia at baseline was associated with a substantial reduction in diarrhea risk. Multivariate statistical analysis showed that this protection could not be explained by differences in age or walking distance to the dispensary between children with and without Giardia. Because we cannot exclude that children differed in other (unmeasured) characteristics, we cannot draw firm conclusions about the causality of the observed association, but our findings support the view that the parasite is not an important cause of diarrhea in highly endemic settings. Striking was that the Giardia-associated protection was lost when children received multi-nutrients. Our data do not provide information about the mechanisms involved, but suggest that multi-nutrients may influence the compositionor pathogenicity of intestinal biota

Some reproductive traits of the Tristan klipfish, Bovichtus diacanthus (Carmichael 1819) (Notothenioidei: Bovichtidae) from Tristan da Cunha (South Atlantic)

The reproductive biology of the Tristan klipfish, Bovichtus diacanthus, was investigated by macroscopic and histological analyses of the gonads. Fish samples were collected in tide pools at Tristan da Cunha in July 2004. Most specimens of both sexes were developing, or sexually mature, with a gonadosomatic index (GSI) of 7.0-9.2% in females and 0.2-0.6% in males. Histologically, testes showed a random distribution of spermatogonia along the lobules, a condition defined as the unrestricted spermatogonial type. Ripe males exhibited lobules with all spermatogenic stages of development from spermatogonia to spermatozoa. In mature females, the ovarian follicles consisted of three main cohorts of oocytes of different sizes; the smaller one represented by previtellogenic oocytes of 15-150 mu m and the other two by yolked oocytes measuring, respectively, 300-1000 and 800-1500 mu m. The overlap between the stock of advanced yolked oocytes and the early yolked oocytes was low, decreasing progressively with final maturation. As a result, B. diacanthus was considered a batch spawner, with a spawning season extending from July to August onward. Batch fecundity, based on the most advanced yolked oocytes, was 2,047-8,317 mature oocytes/female, whereas the relative fecundity was 77-141 mature oocytes/g. In the light of the phyletically basal position of bovichtids in the suborder, the reproductive traits of B. diacanthus were compared with those previously described in other Antarctic and non-Antarctic notothenioids