An obesity paradox has been proposed in many conditions including HIV. Studies conducted to investigate obesity and its effect on HIV disease progression have been inconclusive and are lacking for African settings. This study investigated the relationship between overweight/obesity (BMI≥25 kg/m2) and HIV disease progression in HIV+ asymptomatic adults not on antiretroviral treatment (ART) in Botswana over 18 months. A cohort study in asymptomatic, ART-naïve, HIV+ adults included 217 participants, 139 with BMI of 18·0–24·9 kg/m2 and seventy-eight participants with BMI≥25 kg/m2. The primary outcome was time to event (≥25 % decrease in cluster of differentiation 4 (CD4) cell count) during 18 months of follow-up; secondary outcomes were time to event of CD4 cell count<250 cells/µl and AIDS-defining conditions. Proportional survival hazard models were used to compare hazard ratios (HR) on time to events of HIV disease progression over 18 months. Higher baseline BMI was associated with significantly lower risk of an AIDS-defining condition during the follow-up (HR 0·218; 95 % CI 0·068, 0·701; P=0·011). Higher fat mass at baseline was also significantly associated with decreased risk of AIDS-defining conditions during the follow-up (HR 0·855; 95 % CI 0·741, 0·987; P=0·033) and the combined outcome of having CD4 cell count≤250/µl and AIDS-defining conditions, whichever occurred earlier (HR 0·918; 95 % CI 0·847, 0·994; P=0·036). All models were adjusted for covariates. Higher BMI and fat mass among the HIV-infected, ART-naïve participants were associated with slower disease progression. Mechanistic research is needed to evaluate the association between BMI, fat mass and HIV disease progression.

The Global Plan of Action (GPA) for Animal Genetic Resources (AnGR) adopted by FAO recognizes the role of AnGR for food security through improved productivity while maintaining genetic diversity. A critical issue for conservation and genetic improvement programmes is the availability of supportive infrastructure. The objective of the present study was to assess existing and needed infrastructure for sustainable use of AnGR in a sample of countries in Southern and Eastern Africa. Information was primarily obtained from semi-structured interviews with key personnel in animal breeding during country visits. Countries studied are at different stages of development. No complete breeding programmes are in place but some conservation programmes exist in most countries. Except for a few cases, livestock recording as basis for R&D and breeding practice is lacking. The institutional setup to support animal breeding programmes is fragmented and needs to be better integrated. Shortage of skilled personnel is noted as the most serious constraint for development. Countries with least university training in animal breeding have least developed AnGR activities. However, since the GPA was agreed upon, many countries have re-casted their policies and make efforts to develop breeding policies. A change in mindsets aiming at closer collaboration among institutions, farmer involvement and capacity development and strengthening at all levels is suggested.

Although the application of small quantities of nitrogen (N) fertiliser has improved cereal yields on low-input farms in semi-arid Zimbabwe, the practice is reported to be laborious and time-consuming by farmers. In an effort to make micro-dosing less labour-intensive and more precise, an ammonium nitrate (AN) tablet, the equivalent of a micro-dose of prill AN (28 kg N ha−1) applied per maize plant, was developed by International Crops Research Institute for the Semi-Arid Tropics in collaboration with Agri-Seeds, Zimbabwe. This study characterized the physical stability, chemical (N% and solubility) and agronomic performance of AN tablets compared with prill AN. Only 10% of tablets broke when dropped from 2 m, showing that they are physically stable and can handle rough treatment. The N content in the tablets (33.3%) was comparable to that in prill AN (34.6%). However, the tablet formulation took twice as long to dissolve than prill AN when placed on a wet soil. Despite this difference in solubility, simple leaching column experiments suggest that less than 2% of the total AN applied was lost due to leaching. Agronomic trials were superimposed on the paired-plot demonstrations used to promote micro-dosing and the conservation agriculture tillage technique of planting basins from 2005 to 2008. Each tillage (plough and basins) plot was subdivided into three sub-plots on which no AN, prill AN and tableted AN treatments were superimposed. Maize was planted and management of plots was left to farmers. Micro-dosing with either prill or tableted AN significantly (p < 0.001) increased maize grain yield by over 40% in all seasons for planting basins. However, on the ploughed plot there was no yield benefit to using either AN formulation in the season with the lowest rainfall (2006–2007). There was no significant difference in grain yield and agronomic N use efficiency between prill and tableted AN formulations except for the 2005–2006 season in planting basins. During this season, in planting basins, tableted AN had significantly (p < 0.001) higher rainwater productivity than prill AN, which translated into greater grain yield. In addition, the maximum benefit to micro-dosing was observed to accrue when combined with water harvesting techniques such as planting basins. An observation supported by the host farmers, who in the second and third seasons chose to apply available basal soil fertility amendments to the basin plots over the flat plots. Thus, AN tablets if available at an affordable price can be used by smallholder farmers to more precisely apply N fertiliser. Future work should focus on the labour issues of micro-dosing, and making cost-effective tablets available to resource-poor farmers and also addressing other limiting soil nutrients.

Between August 1978 and July 1979, freshwater gastropods were collected at monthly intervals from 9 different non-lacustrine habitats in the Mwanza region of Tanzania. Of a total of 11708 gastropods representing 14 species, 1748 (14–9%) were infected with trematode sporocysts and/or rediae. Altogether 38 morphologically distinguishable ‘species’ of cercariae were recovered (13 furcocercous, 10 xiphidiocercaria, 6 echin-ostome, 4 cystophorous, 3 gymnocephalous and 2 amphistome species), 22 of which did not conform to previously described African species. The majority (63–8%) of all mature infections were xiphidiocercariae. Biomphalaria pfeifferi, B. sudanica and Ceratophallus natalensis each yielded 11 species of cercariae. Lymnaea natalensis had the highest overall prevalence of infection (36–9%). Cercaria guttera from L. natalensis accounted for 20–4% of all recovered trematode infections and C. blukwa from Biomphalaria accounted for 18–4% of all infections; the high prevalence of these two xiphidiocercariae may alter the transmission patterns of Fasciola gigantica and Schistosoma mansoni, respectively. S. mansoni was recovered from both B. sudanica (22 of 2393 infected) and B. pfeifferi (79 of 1913 infected); S. haematobium (or related species) was recovered from Bulinus (Physopsis) nasutus (50 of 1503 infected) and to a lesser extent from B. (P.) africanus (6 of 186 infected). The findings are discussed in relation to the biological control of trematode diseases in Tanzania.