Quality-quantity trade-off of human offspring under adverse environmental conditions.

A central paradigm in life-history theory is the trade-off between offspring number and quality. Several studies have investigated this trade-off in humans, but data are inconclusive, perhaps because prosperous socio-cultural factors mask the trade-off. Therefore, we studied 2461 offspring groups in an area under adverse conditions in northern Ghana with high fertility and mortality rates. In a linear mixed model controlling for differences in age and tribe of the mother and socioeconomic status, each additional child in the offspring group resulted in a 2.3% (95% CI 1.9-2.6%, P < 0.001) lower proportional survival of the offspring. Furthermore, we made use of the polygamous population structure and compared offspring of co-wives in 388 households, thus controlling for variation in resources between compounds. Here, offspring survival decreased 2.8% (95% CI 2.3-4.0%, P < 0.001) for each increase in offspring number. We interpret these data as an apparent quality-quantity trade-off in human offspring.

Performance of the whole-blood stimulation assay for assessing innate immune activation under field conditions.

Innate propensity of immune activation is reflected in production of pro- and anti-inflammatory cytokines upon stimulation of Toll-like receptors (TLR) in whole-blood stimulation assays. The validity of the whole-blood stimulation assay under field conditions has not been evaluated extensively. Here, we have determined correlation of individually repeated whole-blood stimulation assays in a field-study in Ghana and compared it with that of two Dutch populations performed under optimal conditions. We also examined cytokine production to various TLR-agonists in order to create an assay that would mimic general innate immune responses. Under field conditions repeated assessments of lipopolysaccharide-induced Tumor Necrosis Factor-alpha (TNFalpha) production were poorly correlated (r=0.15, p=0.087). Correlation was relatively high for production of Interleukin-10 (IL10) (r=0.48, p<0.001) and comparable to that observed in the Dutch population under optimal conditions. Combined stimulation with lipopolysaccharide and zymosan resulted in cytokine production profiles that were similar to that attained after stimulation with a mixed culture of bacteria. Here, we conclude that variation of a whole-blood assay performed in field setting is large in general but that production of IL10 seems to better reflect an innate pro- or anti-inflammatory tendency whereas production of TNFalpha may predominantly reflect recent immunological challenges. Furthermore, simultaneous stimulation of several Toll-like receptors may mimic general innate immune activation.

Low-cost interventions accelerate epidemiological transition in Upper East Ghana.

Before the 1950s effective medical interventions were not available and epidemiological transition in developing countries was mostly initiated by the introduction of mains water, sewage systems and personal hygiene. Nowadays, effective medical interventions such as vaccination programmes, medication and vitamin supplements might aid a swift transition. We recorded mortality among a research population of 18850 in Garu-Tempane district of Ghana from 2002 to 2005. We calculated the expected mortality based on the population structure in 2002 and compared the life expectancy of the region with other countries depending on their gross domestic product (GDP). Mortality in the age group 0-9 years was 8.1 per 1000 person-years and in the age group 10-19 years it was 4.1 per 1000 person-years. Cumulative survival probability up to age 20 years amounted to 89% and was far higher than expected. Observed and expected mortality in old age were similar. The life expectancy at birth was 59 years and much higher than the region's per capita annual income of US$100 would predict. We conclude that the population is in epidemiological transition. It shows that an epidemiological transition can be accelerated with low-cost interventions.