Nursing and community rates of Mycobacterium tuberculosis infection among students in Harare, Zimbabwe.

BACKGROUND: African hospitals have experienced major increases in admissions for tuberculosis, but they are ill-equipped to prevent institutional transmission. We compared institutional rates and community rates of tuberculin skin test (TST) conversion in Harare, Zimbabwe. METHODS: We conducted a cohort study of TST conversion 6, 12, and 18 months into training among 159 nursing and 195 polytechnic school students in Harare. Students had negative TST results (induration diameter, or =10 mm) per 100 person-years (95% confidence interval [CI], 14.2-26.2 conversions per 100 person-years), and polytechnic school students experienced 6.0 (95% CI, 3.5-10.4) conversions per 100 person-years. The rate of difference was 13.2 conversions (95% CI, 6.5-20.0) per 100 person-years. With a more stringent definition of conversion (increase in the induration diameter of > or =10 mm to at least 15 mm), which is likely to increase specificity but decrease sensitivity, conversion rates were 12.5 and 2.8 conversions per 100 person-years in nursing and polytechnic school students, respectively (rate difference, 9.7 conversions per 100 person-years; 95% CI, 4.5-14.8 conversions per 100 person-years). Nursing students reportedly nursed 20,868 inpatients with tuberculosis during 315 person-years of training. CONCLUSIONS: Both groups had high TST conversion rates, but the extremely high rates among nursing students imply high occupational exposure to Mycobacterium tuberculosis. Intense exposure to inpatients with tuberculosis was reported during training. Better prevention, surveillance, and management of institutional M. tuberculosis transmission need to be supported as part of the international response to the severe human immunodeficiency virus infection epidemic and health care worker crisis in Africa

FEASIBILITY OF WINTER COVER CROP PRODUCTION UNDER RAINFED CONDITIONS IN THE EASTERN CAPE PROVINCE OF SOUTH AFRICA

Low winter rainfall poses a challenge to production of high biomass from cover crops, which is necessary for the success of conservation agriculture systems in the Eastern Cape Province of South Africa. An experiment was conducted to evaluate the adaptability of white oats ( Avena sativa ), grazing vetch ( Vicia dasycarpa ), rye grass ( Lolium multiflorum ), barley ( Hordeum vulgare ), radish ( Raphanus sativa ) and triticale ( Triticale secale ) production under low winter rainfall conditions in the Eastern Cape. The cover crop species were relayed into maturing maize ( Zea mays L.) in February, March and April of 2010, exposing them to varying rainfall conditions. They were followed with summer maize. Growth rate and final biomass of cover crop species decreased with delayed planting, except for radish. February planted cover crops had the lowest residues remaining at maize planting, resulting in higher weed dry weights at 3 and 6 weeks after planting (WAP). April planted cover crops improved soil N by a greater margin compared to earlier plantings, which were comparable within their category. Grazing vetch and radish resulted in the greatest soil N improvement. Significantly higher (P<0.05) maize grain yield was recorded in grazing vetch, while all other species had comparable yields. It is, thus feasible to produce cover crops under winter rainfall conditions in the Eastern Cape and grazing vetch and radish can serve this purpose.Une faible pluviosité en temps d’hiver constitue une contrainte majeur à la production d’une biomasse suffisante des cultures de couverture nécessaires pour la réussite des systèmes d’une agriculture de conservation en province Est du Cape en Afrique du Sud. Une étude était conduite pour évaluer l’adaptabilité de l’avoine ( Avena sativa ), le vesce ( Vicia dasycarpa ), l’ivraie ( Lolium multiflorum ), l’orge ( Hordeum vulgare ), le radis (Raphanus sativa) et le triticale ( Triticale secale ) en conditions de basses pluviosité de l’Est de Cape. Les espèces de cultures de couverture étaient relayées sur le maïs ( Zea mays L.) en pleine croissance en Fevrier, Mars et Avril 2010, les soumettant ainsi à des conditions de pluviométrie variées, suivi en suite de la culture de maïs en été. Le taux de croissance et la biomasse des cultures de couverture ont diminué avec le semis retardé excepté pour le radis. Les plantes de couverture plantées en Fevrier ont produit une plus petite quantité de résidues restantes à la plantation du maïs, résultant en un poids sec plus élevé des herbes envahissantes après 3 et 6 semaines de la plantation. Les plantes de couverture plantées en Avril ont considérablement amélioré l’azote du sol en comparaison aux cultures de couverture plantées plus tôt, ce qui était comparable à l’intérieur de sa catégorie. Le vesce et le radis ont induit une amélioration plus élevée de l’azote. Un rendement significativemet (P<0.05) plus élevé en grain de maïs était observé sous le vesce, pendant que toutes les autres espèces avaient des rendements comparables. Il est donc plus faisable de produire les cultures de couverture en conditions de pluviosité d’hiver à l’ Est de Cape, le vesce et le radis étant pour ce faire les mieux indiqués