Showing papers by "University of Zimbabwe published in 2005"

Determinants of woody cover in African savannas

Abstract: Savannas are globally important ecosystems of great significance to human economies. In these biomes, which are characterized by the co-dominance of trees and grasses, woody cover is a chief determinant of ecosystem properties1–3. The availability of resources (water, nutrients) and disturbance regimes (fire, herbivory) are thought to be important in regulating woody cover1,2,4,5, but perceptions differ on which of these are the primary drivers of savanna structure. Here we show, using data from 854 sites across Africa, that maximum woody cover in savannas receiving a mean annual precipitation (MAP) of less than ,650mm is constrained by, and increases linearly with, MAP. These arid and semi-arid savannas may be considered ‘stable' systems in which water constrains woody cover and permits grasses to coexist, while fire, herbivory and soil properties interact to reduce woody cover below the MAP-controlled upper bound. Above a MAP of ,650mm, savannas are ‘unstable' systems in which MAP is sufficient for woody canopy closure, and disturbances (fire, herbivory) are required for the coexistence of trees and grass. These results provide insights into the nature of African savannas and suggest that future changes in precipitation6 may considerably affect their distribution and dynamics.

Early exclusive breastfeeding reduces the risk of postnatal HIV-1 transmission and increases HIV-free survival

Abstract: Objectives: The promotion of exclusive breastfeeding (EBF) to reduce the postnatal transmission (PNT) of HIV is based on limited data. In the context of a trial of postpartum vitamin A supplementation, we provided education and counseling about infant feeding and HIV, prospectively collected information on infant feeding practices, and measured associated infant infections and deaths. Design and methods: A total of 14 110 mother–newborn pairs were enrolled, randomly assigned to vitamin A treatment group after delivery, and followed for 2 years. At baseline, 6 weeks and 3 months, mothers were asked whether they were still breastfeeding, and whether any of 22 liquids or foods had been given to the infant. Breastfed infants were classified as exclusive, predominant, or mixed breastfed. Results: A total of 4495 mothers tested HIV positive at baseline; 2060 of their babies were alive, polymerase chain reaction negative at 6 weeks, and provided complete feeding information. All infants initiated breastfeeding. Overall PNT (defined by a positive HIV test after the 6-week negative test) was 12.1%, 68.2% of which occurred after 6 months. Compared with EBF, early mixed breastfeeding was associated with a 4.03 (95% CI 0.98, 16.61), 3.79 (95% CI 1.40–10.29), and 2.60 (95% CI 1.21–5.55) greater risk of PNT at 6, 12, and 18 months, respectively. Predominant breastfeeding was associated with a 2.63 (95% CI 0.59–11.67), 2.69 (95% CI 0.95–7.63) and 1.61 (95% CI 0.72–3.64) trend towards greater PNT risk at 6, 12, and 18 months, compared with EBF.

Measuring conditions and trends in ecosystem services at multiple scales: The Southern African Millennium Ecosystem Assessment (SAfMA) experience

Abstract: The Southern African Millennium Ecosystem Assessment (SAfMA) evaluated the relationships between ecosystem services and human well-being at multiple scales, ranging from local through to sub-continental. Trends in ecosystem services (fresh water, food, fuel-wood, cultural and biodiversity) over the period 1990-2000 were mixed across scales. Freshwater resources appear strained across the continent with large numbers of people not securing adequate supplies, especially of good quality water. This translates to high infant mortality patterns across the region. In some areas, the use of water resources for irrigated agriculture and urban-industrial expansion is taking place at considerable cost to the quality and quantity of freshwater available to ecosystems and for domestic use. Staple cereal production across the region has increased but was outstripped by population growth while protein malnutrition is on the rise. The much-anticipated wood-fuel crisis on the subcontinent has not materialized but some areas are experiencing shortages while numerous others remain vulnerable. Cultural benefits of biodiversity are considerable, though hard to quantify or track over time. Biodiversity resources remain at reasonable levels, but are declining faster than reflected in species extinction rates and appear highly sensitive to land-use decisions. The SAfMA sub-global assessment provided an opportunity to experiment with innovative ways to assess ecosystem services including the use of supply-demand surfaces, service sources and sink areas, priority areas for service provision, service 'hotspots' and trade-off assessments.

HIV infection and reproductive health in teenage women orphaned and made vulnerable by AIDS in Zimbabwe.

Abstract: AIDS has increased the number of orphans and vulnerable children (OVCs) in sub-Saharan Africa who could suffer detrimental life experiences. We investigated whether OVCs have heightened risks of adverse reproductive health outcomes including HIV infection. Data on HIV infection, sexually transmitted infection (STI) symptoms and pregnancy, and common risk factors were collected for OVCs and non-OVCs in a population survey of 1523 teenage children in eastern Zimbabwe between July 2001 and March 2003. Multivariate logistic regression was used to test for statistical association between OVC status, adverse reproductive health outcomes and suspected risk factors. Amongst women aged 15–18 years, OVCs had higher HIV prevalence than non-OVCs (3.2% versus 0.0%; p=0.002) and more common experience of STI symptoms (5.9% versus 3.3%; adjusted odds ratio = 1.75, 95% CI 0.80–3.80) and teenage pregnancy (8.3% versus 1.9%; 4.25, 1.58–11.42). OVCs (overall), maternal orphans and young women with an infected paren...

Organic Matter Management as an Underlying Cause for Soil Fertility Gradients on Smallholder Farms in Zimbabwe

Abstract: Management of spatial and temporal variability of soil fertility within fields and farms is one major challenge for increasing farm-level crop productivity in smallholder agriculture. A study was conducted across 120 on-farm field sites in three agro-ecological regions of Zimbabwe to identify management factors influencing the formation of within-field/farm soil fertility gradients. Using farmer participatory research approaches, host farmers were put into three classes according to resource endowment, namely, Resource-endowed, Intermediate and Resource-constrained farmers. Each host farmer identified the most (rich) and least (poor) productive field or field section, which were then studied over two years. Farmer criteria for defining soil fertility ranged from colour through elements of soil structure to crop response following external nutrient inputs. The fertility ranking of fields consistently matched with laboratory indices, with rich fields containing significantly more soil organic carbon (SOC) and nutrients than the corresponding poor fields. Fertility gradients were evident within and across farms belonging to different farmer classes. The mean SOC content for rich fields were >6.0 g kg−1 compared with <4.6 g kg−1 for the designated poor fields. Rich fields belonging to Resource-endowed farmers had 16–28% more SOC than those belonging to their resource-constrained counterparts, suggesting differences in organic matter management. Differences in SOC and fertility status between rich and poor fields were wider in two of the study areas which had more than 70 years of cultivation in contrast to the third site which had been under smallholder farming for only 20 years, suggesting that the observed fertility gradients are a cumulative effect of years of differential management practices by different farmer classes. Analysis of potential benefits from in situ organic biomass inputs suggested that the processes of organic matter capture and utilization discriminated against Resource-constrained farmers. About 50% of in situ biomass, preferentially maize stover, was lost in three dry season months, and up to 72% of potentially recyclable N is lost from poor fields managed by Resource-constrained farmers. In contrast, Resource-endowed farmers incorporated more than 1.5 t C, 25 kg N and 5 kg P ha−1 season−1 because of their access to draught power during the early dry season. Such inputs could make a difference on these nutrient-depleted soils. Intermediate farmers represented a diverse transitional group whose size and variability could be indicative of the dynamism of technology usage. It was concluded that management of soil fertility gradients to increase crop productivity on smallholder farms hinges on increasing the capacity and efficiency with which organic matter is generated and utilized by different farmer weaclth groups across temporal scales.

The Southern Africa Fire Network (SAFNet) regional burned‐area product‐validation protocol

Abstract: The development of appropriate validation techniques is critical to assess uncertainties associated with satellite-data-based products, to identify needed product improvements and to allow products to be used appropriately. At regional to global scales, there are several outstanding issues in the development of robust validation methodologies, including the need to increase the quality and economy of product validation by developing and promoting international validation standards and protocols. This paper describes a protocol developed to validate a regional southern Africa burned-area product derived from Moderate Resolution Imaging Spectroradiometer (MODIS) 500 m time series data. The protocol is based upon interpretations by members of the Southern Africa Fire Network (SAFNet) of multitemporal Landsat Enhanced Thematic Mapper plus (ETM + ) data to derive maps of the location and approximate date of burning. The validation data are derived using Landsat ETM + scenes distributed to

Patterns of movement and risk of HIV infection in rural Zimbabwe.

Abstract: Background. High rates of population movement may have helped spread human immunodeficiency virus (HIV) in southern Africa, including Zimbabwe, but whether mobility continues to influence the epidemic is unclear. Methods. The relationship between movement, risk behaviors, and prevalence of HIV was assessed from a general population survey of >9800 adults in 12 rural communities in Manicaland province in eastern Zimbabwe. Results. HIV prevalence varied with socioeconomic development. In community centers, prevalence among women was 49.9% (95% confidence interval [CI], 46.1%-53.6%), compared with 24.7% (95% CI, 22.6%-26.7%) in the least-developed subsistence-farming areas. Mobility was not associated with risk of HIV infection, except for those who migrated between rural locations. Among migrant agricultural workers, prevalence was 38.8% (95% CI, 33.1%-44.6%) for women and 26.4% (95% CI, 23.8%-28.9%) for men, compared with 29.7% (95% CI, 28.3%-31.1%) and 20.9% (95% CI, 19.3%-22.4%) for other sexually active women and men, respectively. Risk was increased if an individual traveled to Harare in the last month, without their spouse, but this risk was not transferred to the partner. Conclusion. Rural-urban migration does not appear to be responsible for maintaining the high HIV prevalence in rural Zimbabwe, but rates of HIV infection may be affected by rural-rural migration.

Long-term changes in organic matter of woodland soils cleared for arable cropping in Zimbabwe

Abstract: Subsistence farmers in Africa depend largely on the soil organic matter to sustain crop productivity. Long-term changes in soil organic carbon and nitrogen were measured after woodland clearance for smallholder subsistence farming or for commercial farming. The contents of organic carbon and nitrogen in soil under reference woodlands were largest (53.3 t C ha-1, 4.88 t N ha-1) in a red clay soil (~ 50% clay + silt), followed by a granitic sand (~ 12% clay + silt; 22.8 t C ha-1, 1.47 t N ha -1) and least (19.5 t C ha-1, 0.88 t N ha-1) in a Kalahari sand (~ 5% clay + silt). Organic carbon declined rapidly under cultivation to attain new equilibria within 10 years on all smallholdings. Greatest losses occurred in soils that initially contained most carbon and nitrogen in the order: red clay (22.4 t C ha-1 and 1.0 t N ha -1) > granitic sand (13.2 t C ha-1 and 0.8 t N ha -1) > Kalahari sand (10.6 t C ha-1 and 0.5 t N ha -1). On the clay soil, commercial farming with intensive use of mineral fertilizers and incorporation of maize stover led to more gradual decline: at equilibrium, contents of carbon and nitrogen were 15 t C ha -1 and 1.7 t N ha-1 greater than on smallholdings with similar soil and climate. In the Kalahari sand the ?13C of organic C remained constant after woodland clearance, and maize contributed less than 10% of the total C even after 55 years. The ?13C signature increased slightly with increasing duration of cultivation by smallholders in the granitic sands and red clay soil where maize contributed 29% and 35% of the C at equilibrium. Under more productive commercial farming, the carbon derived from maize accounted for 50% of the total after 10 years of cultivation and 67% at equilibrium. The persistence of woodland carbon in the sandy soil is attributed to chemical stabilization resulting from large concentrations of lignin and polyphenols in the tree litter, or as charcoal.

Schistosomiasis and HIV-1 Infection in Rural Zimbabwe: Effect of Treatment of Schistosomiasis on CD4 Cell Count and Plasma HIV-1 RNA Load

Abstract: To determine whether of schistosomiasis has an effect on the course of human immunodeficiency virus type 1 (HIV-1) infection individuals with schistosomiasis and with or without HIV-1 infection were randomized to receive praziquantel treatment at inclusion or after a delay of 3 months; 287 participants were included in the study and 227 (79%) were followed up. Among the 130 participants who were coinfected those who received early treatment (n = 64) had a significantly lower increase in plasma HIV-1 RNA load than did those who received delayed treatment (n = 66) (P <.05); this difference was associated with no change in plasma HIV-1 RNA load in the early intervention group (P = .99) and an increase in plasma HIV-1 RNA load in the delayed intervention group (P <.01). Among the 227 participants who were followed up those who received early treatment (n = 105) had an increase in CD4 cell count whereas those who received delayed treatment (n = 122) did not (P <.05); this effect did not differ between participants when stratified by HIV-1 infection status (P = .17). The present study suggests that treatment of schistosomiasis can reduce the rate of viral replication and increase CD4 cell count in the coinfected host. (authors)

On farm evaluation of the effect of low cost drip irrigation on water and crop productivity compared to conventional surface irrigation system

Abstract: This on-farm research study was carried out at Zholube irrigation scheme in a semi-arid agro tropical climate of Zimbabwe to determine how low cost drip irrigation technologies compare with conventional surface irrigation systems in terms of water and crop productivity. A total of nine farmers who were practicing surface irrigation were chosen to participate in the study. The vegetable English giant rape ( Brassica napus ) was grown under the two irrigation systems with three fertilizer treatments in each system: ordinary granular fertilizer, liquid fertilizer (fertigation) and the last treatment with no fertilizer. These trials were replicated three times in a randomized block design. Biometric parameters of leaf area index (LAI) and fresh weight of the produce, water use efficiency (WUE) were used to compare the performance of the two irrigation systems. A water balance of the inflows and outflows was kept for analysis of WUE. The economic profitability and the operation, maintenance and management requirements of the different systems were also evaluated. There was no significant difference in vegetable yield between the irrigation systems at 8.5 ton/ha for drip compared to 7.8 ton/ha in surface irrigation. There were significant increases in yields due to use of fertilizers. Drip irrigation used about 35% of the water used by the surface irrigation systems thus giving much higher water use efficiencies. The leaf area indices were comparable in both systems with the same fertilizer treatment ranging between 0.05 for surface without fertilizer to 6.8 for low cost drip with fertigation. Low cost drip systems did not reflect any labour saving especially when manually lifting the water into the drum compared to the use of siphons in surface irrigation systems. The gross margin level for surface irrigation was lower than for low cost drip irrigation but the gross margin to total variable cost ratio was higher in surface irrigation systems, which meant that surface irrigation systems gave higher returns per variable costs incurred. It was concluded that low cost drip systems achieved water saving of more than 50% compared to surface irrigation systems and that it was not the type of irrigation system that influenced the yield of vegetables significantly but instead it is the type of fertilizer application method that contribute to the increase in the yield of vegetables. It was recommended that low cost technologies should be used in conjunction with good water and nutrient management if higher water and crop productivity are to be realized than surface irrigation systems.

Praziquantel Treatment of Individuals Exposed to Schistosoma haematobium Enhances Serological Recognition of Defined Parasite Antigens

Abstract: Background Schistosomiasis is a major parasitic disease affecting >200 million people in the developing world, and 400 million people are at risk for infection. This study aimed to identify and compare proteins recognized by serum samples from schistosome-exposed individuals before and after curative praziquantel treatment. Methods Proteins recognized by pooled serum samples from Schistosoma haematobium-exposed Zimbabweans were determined by 2-dimensional Western blotting and identified by mass spectrometry. Results Serum samples recognized 71 spots, which resolved to 26 different characterized proteins. Eleven of these proteins have not previously been shown to be immunogenic in natural human infection or in experimental models of schistosomiasis, making them novel antigens in the parasite. Pretreatment serum samples recognized 59 spots, which resolved to 21 different identified proteins. Posttreatment serum samples recognized an additional 12 spots, which resolved to 8 different identified proteins. Of these 8 proteins, 3 had putative isoforms recognized before treatment, and 5 (calreticulin, tropomyosin 1, tropomyosin 2, paramyosin, and triose phosphate isomerase) did not. Conclusions This study is the most comprehensive characterization of S. haematobium antigens to date and describes novel antigens in all schistosome species. Posttreatment results are consistent with praziquantel treatment inducing quantitative and qualitative changes in schistosome-specific antibody responses.

Active biomonitoring in freshwater environments: early warning signals from biomarkers in assessing biological effects of diffuse sources of pollutants

Abstract: Effluents are a main source of direct and continuous input of pollutants in aquatic ecosystems. Relating observed effects to specific pollutants or even classes of pollutants remains a very difficult task due to the usually unknown, complex and often highly variable composition of effluents. It is recognized that toxicants interfere with organism integrity at the biochemical level and give rise to effects at the individual level and is manifested in reduced ecologically relevant characteristics such as growth, reproduction and survival, and ultimately at the ecosystem level. By integrating multiple endpoints at different ecologically relevant levels of organization within one test organism, it should be possible to gain understanding in how different levels of organization within this organism respond to toxic exposure and how responses at these different levels are interrelated. This paper presents results from a field study in the Rietvlei Wetland system, Gauteng, South Africa using the freshwater mollusk (Melanoides tuberculata) and freshwater fish (Oreochromis mossambicus) as bioindicator organisms. Active biomonitoring (ABM) exposures were conducted where organisms were exposed for 28 days in an effluent dominated river during high flow conditions in April 2003. The river receives effluent from a wastewater treatment plant and an industrial complex, so that up to 75% of the total flow of the river is effluent-based. Effects of field exposure were determined using cellular biomarkers e.g. DNA damage, HSP 70, metallothionein, acetylcholine esterase, lactate dehydrogenase and ethoxyresorufin-odeethylase activity. The results clearly indicate that although the traditional mortality-based whole effluent toxicity testing did not indicate any toxicity, the in situ exposed organisms were stressed. A multivariate statistical approach was particularly useful for integrating the biomarker responses and highlighting sites at which more detailed analysis of chemical contamination would be useful. Based on the individual biomarker results contributing towards the distinct groupings it is possible to conclude that Site 1 is subjected to organic pollutants, whereas Sites 2 and 3 undergo a combination of metallic and organic pollutant stress. However, it is essential that a rapid and sensitive biomarker that is representative of the responses of a suite of biomarkers be tested before ABM can be implemented as a routine biomonitoring practice in water resource management. � 2005 Elsevier Ltd. All rights reserved.

The response of elephants to the spatial heterogeneity of vegetation in a Southern African agricultural landscape

Abstract: Based on the agricultural landscape of the Sebungwe in Zimbabwe, we investigated whether and how the spatial distribution of the African elephant (Loxodonta africana) responded to spatial heterogeneity of vegetation cover based on data of the early 1980s and early 1990s. We also investigated whether and how elephant distribution responded to changes in spatial heterogeneity between the early 1980s and early 1990s. Vegetation cover was estimated from a normalised difference vegetation index (NDVI). Spatial heterogeneity was estimated from a new approach based on the intensity (i.e., the maximum variance exhibited when a spatially distributed landscape property such as vegetation cover is measured with a successively increasing window size or scale) and dominant scale (i.e., the scale or window size at which the intensity is displayed). We used a variogram to quantify the dominant scale (i.e., range) and intensity (i.e., sill) of NDVI based congruent windows (i.e., 3.84 km × 3.84 km in a 61 km × 61 km landscape). The results indicated that elephants consistently responded to the dominant scale of spatial heterogeneity in a unimodal fashion with the peak elephant presence occurring in environments with dominant scales of spatial heterogeneity of around 457–734 m. Both the intensity and dominant scale of spatial heterogeneity predicted 65 and 68% of the variance in elephant presence in the early 1980s and in the early 1990s respectively. Also, changes in the intensity and dominant scale of spatial heterogeneity predicted 61% of the variance in the change in elephant distribution. The results imply that management decisions must take into consideration the influence of the levels of spatial heterogeneity on elephants in order to ensure elephant persistence in agricultural landscapes.

Nurse Migration From Zimbabwe: Analysis Of Recent Trends And Impacts

Abstract: The migration of nursing professionals from developing countries such as Zimbabwe to industrialised countries is taking place at an alarming rate, with little signs of slowing down. In Africa, nurses form the backbone of the healthcare delivery system and their migration has a huge negative impact on health service provision. Drawing on evidence from selected health institutions, the paper shows the magnitude of migration of nurses from Zimbabwe. The paper also shows that public to private health sector migration of nurses is occurring at a significant rate. The effects of such movements are examined in detail. For instance, at the health institution level, nurse migration has led to staff shortages, and health institutions located in the disadvantaged areas have been the worst affected. The paper calls for the adoption of an integrated approach in managing and addressing the concerns of the nursing professionals.

An assessment of the effect of human faeces and urine on maize production and water productivity

Abstract: The key challenge facing many catchment authorities in Zimbabwe and elsewhere is the challenge of feeding the growing populations within their catchment boundaries. Modern agricultural practices continue to mine valuable crop nutrients through increased food production to satisfy ever-increasing food demand. In recent diagnostic survey of smallholder agricultural sector in the Manyame catchments of Zimbabwe it was revealed that exhausted soils depleted of their natural mineral and organic constituents by many years of cropping with little fertilization or manuring were the major factors contributing to low yields and poor food security in this sector in Zimbabwe. The objective of the study was to assess the effect of using sanitized human excreta on maize production and water productivity. The study involved six volunteer farmers with four 10 m × 10 m trial plots each with the following treatments the control, commercial fertilizer treatment urine only plot, and the feacal matter and urine plot. Harvest determination was carried by weighing the yield from each of the treatment plots and comparisons done. Water productivity was computed by calculating the amount of water used to produce a tone of maize per ha. The study showed that human excreta improves maize crop production and water productivity in rain-fed agriculture. The study recommends that the ecological sanitation concept and the reuse of human excreta both humanure and (ecofert) urine can be considered as alternative excreta management options in catchment areas.

Incidence of stillbirth and perinatal mortality and their associated factors among women delivering at Harare Maternity Hospital, Zimbabwe: a cross-sectional retrospective analysis

Abstract: Background Death of an infant in utero or at birth has always been a devastating experience for the mother and of concern in clinical practice. Infant mortality remains a challenge in the care of pregnant women worldwide, but particularly for developing countries and the need to understand contributory factors is crucial for addressing appropriate perinatal health.

Schistosomiasis and HIV-1 Infection in Rural Zimbabwe: Implications of Coinfection for Excretion of Eggs

Abstract: Background. Stunted development and reduced fecundity of Schistosoma parasites in immunodeficient mice and the impaired ability of human immunodeficiency virus 1 (HIV-1)-infected humans to excrete schistosome eggs have been described. This study explores the effect that HIV-1-associated immunodeficiency has on the excretion of schistosome eggs in a large cohort of coinfected individuals. Methods. In a cross-sectional survey, urine and stool samples were obtained from and HIV-1 status was determined for 1545 individuals. More extensive data, including quantitative measures of intensity of infection in schistosomiasis and immunodeficiency, were collected in the Mupfure schistosomiasis and HIV longitudinal cohort, composed of 379 participants of whom 154 were coinfected with HIV-1 and Schistosoma parasites. Results. In the cross-sectional survey, the overall prevalence of schistosomiasis was 43.4%, and 26.3% of the participants were infected with HIV-1. Schistosome infections were due to Schistosoma haematobium in 63.6% of cases, S. mansoni in 18.1% of cases, and dual infections in 18.4% of cases. Intensities of Schistosoma infections, measured by the number of eggs excreted and by the level of circulating anodic antigens, did not differ between HIV-1-negative and HIV-1-positive participants coinfected with S. haematobium, S. mansoni, or both. CD4 cell counts were significantly lower in HIV-1-positive participants and in S. mansoni-infected HIV-1-negative participants than in other participants. Conclusion. The present study suggests that adult HIV-1-related immunodeficiency does not impair the ability to excrete eggs in low-intensity infection with S. haematobium, S. mansoni, or both and that infection with HIV-1 may not have major implications for diagnosis and surveillance of schistosomiasis.

Breast-Milk Shedding of Drug-Resistant HIV-1 Subtype C in Women Exposed to Single-Dose Nevirapine

Abstract: Single-dose nevirapine reduces intrapartum human immunodeficiency virus 1 type (HIV-1) transmission but may also select for nonnucleoside reverse-transcriptase inhibitor (NNRTI) resistance in breast milk (BM) and plasma. Among 32 Zimbabwean women, median 8-week postpartum plasma and BM HIV-1 RNA levels were 4.57 and 2.13 log(10) copies/mL, respectively. BM samples from women with laboratory-diagnosed mastitis (defined as elevated BM Na(+) levels) were 5.4-fold more likely to have HIV-1 RNA levels above the median. BM RT sequences were not obtained for 12 women with BM HIV-1 RNA levels below the lower limit of detection of the assay used. In 20 paired BM and plasma samples, 65% of BM and 50% of plasma RT sequences had NNRTI-resistance mutations, with divergent mutation patterns.

Prediction of flow characteristics using multiple regression and neural networks: A case study in Zimbabwe

Abstract: The feasibility of predicting flow characteristics from basin descriptors using multiple regression and neural networks has been investigated on 52 basins in Zimbabwe. Flow characteristics considered were average annual runoff, base flow index, flow duration curve, and average monthly runoff . Mean annual runoff is predicted using linear equations from mean annual precipitation, basin slope, and proportion of a basin underlain by granite and gneiss. A multiple regression equation is derived to predict the base flow index from mean annual precipitation, slope, and proportion of a basin with grasslands. Findings indicate that a neural network predicts the base flow index with comparable accuracy to multiple regression. Differences in lithology and land cover type were not significant in explaining the base flow index. An exponential model was able to describe flow duration curves, and coefficients of this model could be predicted from the base flow index. Best predictions of flow duration curves were made by a neural network from base flow index, slope, and proportion of a basin with grasslands. The distribution of mean annual runoff into monthly flows was predicted by a neural network from base flow index, slope, and proportion of a basin with grasslands. The study found the base flow index to be important for predicting flow characteristics, and recommends studies aimed at improving prediction of the base flow index.

Symbiotic effectiveness and host ranges of indigenous rhizobia nodulating promiscuous soyabean varieties in Zimbabwean soils

Abstract: Presence of indigenous rhizobia nodulating promiscuous soyabean was determined in 92, mainly sandy soils, from wetter agro-ecological zones of Zimbabwe suited to soyabean production. A total of 129 isolates were obtained from nodules of promiscuous soyabean varieties, Magoye and Hernon 147, and a specific variety, Roan grown in potted soils. Magoye nodulated in 80%, Hernon 147 in 50% and Roan in only 25% of the 92 soils tested. Rhizobia populations ranged from undetectable to 2.4×10 4 cells g −1 of soil. Twenty-one of these isolates were tested for symbiotic effectiveness on two varieties, promiscuous Magoye and specific Roan. Differences in parameters such as nodule numbers, nodule weights and total N fixed reflected diversity among the indigenous isolates. Three isolates had significantly higher N 2 -fixing potential in comparison with the commercial strain MAR 1491 on promiscuous Magoye. Host ranges of 34 isolates were evaluated on nine legume species: Arachis hypogaea , Cajanus cajan , Crotalaria juncea , Glycine max , Macroptilium atropurpureum , Phaseolus vulgaris, Sesbania sesbania , Vigna subterranea , Vigna unguiculata . Of these 34 isolates, 33 formed nodules with M. atropurpureum of which 61% were moderately effective to very effective while all nodulated V. unguiculata with 58% being moderately effective to very effective. Twenty-eight isolates nodulated V. subterranea and C. cajan (short season variety) with 76 and 36% of these being moderately to very effective, respectively. None of the isolates formed nodules on Phaseolus vulgaris , Arachis hypogaea or Sesbania sesban . Our results indicate that the ability of even specific varieties of soyabean to nodulate with indigenous isolates in African soils is greater than generally assumed.

Village Chicken Flock Dynamics and the Contribution of Chickens to Household Livelihoods in a Smallholder Farming Area in Zimbabwe

Abstract: The development of successful production strategies for poultry rearing depends on an accurate description of village chicken production systems. In Rushinga District of Zimbabwe, participatory rural appraisals (PRAs) followed by checklists and intensive case studies were carried out in three villages. The role of chickens in the livelihoods of households was evaluated. Flock dynamics were monitored monthly for 24 months. Women who were resident on the farm headed 19% of the households. A household comprised 4.8±2.5 members with arable land of approximately 2.6 ha. In addition to chickens, households grew maize, cotton and sunflower and kept large animals. Flocks ranging from 1 to 50 village chickens per household were reared under a scavenging system of management with suboptimal housing, inadequate feeding and poor health care. The use of ethno-veterinary medicine was common in treating sick chickens. The largest flock sizes were observed in the hot-wet season. Over 90% of an average of 5.4 entries/household per month were from hatched chicks. Mortality claimed an average of 80% of the total exits. Chicken production potential (CPP), which defined the proportion of chickens that could be utilized by a household, averaged 50%. Chicken production efficiency (CPE) was approximately 15% of the CPP. Egg consumption patterns were low and similar across seasons.

An Education and Counseling Program for Preventing Breast-Feeding–Associated HIV Transmission in Zimbabwe: Design and Impact on Maternal Knowledge and Behavior

Abstract: International guidance on HIV and infant feeding has evolved over the last decade. In response to these changes, we designed, implemented, and evaluated an education and counseling program for new mothers in Harare, Zimbabwe. The program was implemented within the ZVITAMBO trial, in which 14,110 mother-baby pairs were enrolled within 96 h of delivery and were followed at 6 wk, 3 mo, and 3-mo intervals. Mothers were tested for HIV at delivery but were not required to learn their test results. Infant feeding pattems were determined using data provided up to 3 mo. Formative research was undertaken to guide the design of the program that included group education, individual counseling, videos, and brochures. The program was introduced over a 2-mo period: 11,362,1311, and 1437 women were enrolled into the trial before, during, and after this period. Exclusive breast-feeding was recommended for mothers of unknown or negative HIV status, and for HIV-positive mothers who chose to breast-feed. A questionnaire assessing HIV knowledge and exposure to the program was administered to 1996 mothers enrolling after the program was initiated. HIV knowledge improved with increasing exposure to the program. Mothers who enrolled when the program was being fully implemented were 70% more likely to learn their HIV status early (<3 mo) and 8.4 times more likely to exclusively breast-feed than mothers who enrolled before the program began. Formative research aided in the design of a culturally sensitive intervention. The intervention increased relevant knowledge and improved feeding practices among women who primarily did not know their HIV status.

Acceptability of adult male circumcision for sexually transmitted disease and HIV prevention in Zimbabwe.

Abstract: Worldwide over 35 cross-sectional and prospective studies1–6 various ecologic analyses and investigations of biologic plausibility sexually transmitted infection (STI) epidemiology and a longitudinal study of HIV-discordant heterosexual couples have identified lack of male circumcision as a significant risk factor for HIV acquisition. (However some crosssectional studies have found no correlation and in a Rwandan study women who reported that their current partners were circumcised had an increased risk of HIV.) In the regions of east and southern Africa where heterosexually spread HIV epidemics are especially severe large populations of men are uncircumcised pointing to a possible prevention intervention. Previous studies in 6 sub-Saharan African countries have explored men’s and women’s awareness of the potential health benefits of male circumcision and men’s willingness to undergo adult circumcision. Currently pilot programs to introduce safe affordable circumcision as part of male reproductive health services are being implemented or are planned in Botswana Haiti Kenya South Africa and Zambia. (excerpt)

An assessment of the water quality of drinking water in rural districts in Zimbabwe. The case of Gokwe South, Nkayi, Lupane, and Mwenezi districts

Abstract: Zimbabwe generally receives an average rainfall of 675 mm per annum of which only a maximum of 10% finds its way to rivers as runoff. Gokwe, Nkayi, Lupane and Mwenezi are some of the driest districts in Zimbabwe having mean annual runoffs (MAR) in the range 17–70 mm. River flows especially in Nkayi and Lupane are seasonal and often dry in the period June to November every year. The Kalahari sands predominantly found in such areas as Gokwe, Nkayi, and Lupane promote rapid percolation of rainwater leaving little runoff. The main source of water for domestic purposes in these areas is groundwater with very little reliance on surface water. This study analyzed the water quality of water points in Gokwe South, Nkayi, Lupane, and Mwenezi districts. Parameters analyzed were pH, temperature, dissolved oxygen (DO), turbidity and electrical conductivity (EC). Water quality perceptions from the villagers and the research team were investigated and possible correlations studied. Water quality perceptions included, taste and soap consumption and colour. The uses of the water at domestic level as well as available alternatives to borehole water were investigated. The pH generally ranged from 6.5 to 8.0, which is within the Canadian guidelines. DO was 0.3–5.9 mg/l while turbidity ranged from 0 to 259 NTU with Mwenezi having the highest turbidity value. Conductivity ranged from 70 to 9800 μS/cm with the lowest and highest values recorded in Gokwe and Mwenezi. It was found out that the water quality in terms of taste and odour was 97% satisfactory for Gokwe South, 85% Nkayi, 64% Lupane, and 62% for Mwenezi. High soap consumption which is related to hardness was perceived to be least in Lupane (14%) and highest in Mwenezi with 81%. In general taste complaints also corresponded to high soap consumption but the opposite was not true. It was observed that there was no clear correlation between the quality parameters studied and perceived quality as for example satisfactory taste responses were obtained at EC values higher than the threshold minimum value for objection.

The feasibility of voluntary counselling and HIV testing for pregnant women using community volunteers in Zimbabwe.

Abstract: The purpose of this pilot project was to assess the feasibility and acceptability of voluntary counselling and HIV testing (VCT) by pregnant women using community volunteers in Zimbabwe to prevent mother to child transmission (MTCT) of HIV. From July 1999 to June 2001, a short-course zidovudine (ZDV)-based perinatal HIV prevention programme was initiated in two antenatal clinics. Community volunteers, recruited from local community organizations, underwent a two-week training course in VCT, which included HIV/AIDS facts, systematic counselling approach, and practical counselling techniques using scripts and role-play. Rapid HIV testing was performed after informed consent. Lay counsellors conducted individual pre- and post-test counselling for HIV. A total of 35 women community volunteers were trained in VCT; 34 graduated and committed to work four hours per week in the clinic. Of the 6051 pregnant women presenting for antenatal clinics (ANC), 1824 (30%) underwent pre-test counselling and 1547 (26%) were tested, and 429 (28%) were HIV infected. Overall, 1283 (83%) returned for their test results including 406 (95%) of HIV-infected women. Of the 406 HIV-infected women who collected their test results, only 203 (50%) opted for ZDV prophylaxis to prevent MTCT of HIV. Over the two-year study period, two counsellors died and three sought employment at other organizations. Adherence to duty roster was 97% and no breach of confidentiality was reported. Despite many challenges, VCT delivered by community volunteers is feasible and acceptable for pregnant women aiming to reduce their risk of transmitting HIV to their infants. This programme is being implemented at several urban and rural MTCT sites in Zimbabwe and can serve as a model for other resource-poor countries.