Showing papers by "University of Zimbabwe published in 1988"

A search for ancient detrital zircons in Zimbabwean sediments

Abstract: 86 detrital zircon grains from Archaean quartzites from the Mweza and Shurugwi greenstone belts have been dated by the ion probe SHRIMP. Nine of these give ages of 3.75–3.80 Ga, older than any Zimbabwean rocks so far satisfactorily dated, and the Tokwe-Zvishavane gneisses are a possible source for these old grains. However, none are comparable in age with the 4.2 Ga zircons discovered in Western Australia. If such old grains exist in the sample it is unlikely (P>0.05) that their abundance could exceed 3%. Ages of the younger grains are broadly consistent with the presumed age of the quartzites sampled, though some high Th/U grains in the Shurugwi sample may be anomalously young.

Element interactions in forest ecosystems: succession, allometry and input-output budgets

Abstract: Element interactions within forests differ from those in other major ecosystems for three major reasons: — a greater allocation of carbon to structural material; — a greater element storage within biomass; and — the diversity of carbon- and nutrient-containing metabolites produced. The most important of these differences is structural material, which can lead to C: element ratios in biomass (as a whole) 100 × greater than those in unicellular organisms. Stand allometry causes the amount of carbon stored and C:element ratios in biomass to change in predictable ways in the course of secondary succession. Such changes affect microbial dynamics and C: element interactions within soils. Bicarbonate, organic acids, nitrate, phosphate, and sulfate are major anions within forest soils: they control leaching of both anions and cations. Biotic interactions of C, N, P, and S during both uptake and mineralization control the potential for production of these anions within forests, and geochemical interactions regulate their mobility and loss.

Congenital syphilis in the newborn.

Abstract: We studied 53 newborn babies with congenital syphilis. The common clinical features seen were low birth weight, hepatosplenomegaly, anaemia, jaundice, and symmetrical superficial desquamation of the skin affecting palms and soles. The presence of these clinical signs is highly suggestive of early congenital syphilis. Hydrops fetalis without rhesus or ABO isoimmunisation should always arouse the suspicion of congenital syphilis.

Prevalence and intensity of schistosomiasis in two rural areas in Zimbabwe and their relationship to village location and snail infection rates.

Abstract: Surveys for schistosomiasis of 2498 people of various ages from 22 villages in northeast Zimbabwe are reported. A high prevalence of Schistosoma haematobium (53·1%) and a medium prevalence of S. ma...

Serological diagnosis of neurocysticercosis: evaluation of ELISA tests using cyst fluid and other components of Taenia solium cysticerci as antigens.

Abstract: An ELISA system was developed to assist with the diagnosis of neurocysticercosis. Antigens were prepared from the fluid, the protoscolex and the cyst wall of cysticerci dissected from infected pigs. The fluid antigen was tested both fresh and after freeze-drying and one year's storage. Sera from patients with proven neurocysticercosis were most reactive using the fluid and least reactive using the cyst wall antigens. Freeze-drying and prolonged storage of fluid antigen did not reduce its reactivity and repeated testing of sera with this antigen gave optical density values within 15% of the original value. Using this ELISA system positive results were obtained from all patients with active neurocysticercosis. Sera from patients with calcified cysts were usually non-reactive or marginally reactive to the fluid antigen.

Age distributions and reproductive status of declining and stationary populations of Glossina pallidipes Austen (Diptera: Glossinidae) in Zimbabwe

Abstract: Age structures and reproductive anomalies of two field populations of Glossina pallidipes Austen in Zimbabwe were compared. One population was treated with insecticide sprayed on odour-baited targets, while the other was left undisturbed. Both populations were sampled with F3 prism-type traps. Capture probabilities were higher for females in early stages of pregnancy than for those in later stages. Per-capita mortality rates were estimated from age distributions which had been corrected for rate of increase. The mortality rate steadily increased over time in the insecticide-treated area but remained roughly constant in the undisturbed area. Estimates of mortality had wide confidence intervals, and the mortality model is critically reviewed. No evidence was seen in the treated population for an increased incidence of abortion or other reproductive anomalies, or for a decrease in insemination rate.

Effectiveness of a therapeutic drug monitoring service as an aid to the control of canine seizures

Abstract: The results presented were derived from an anticonvulsant monitoring service, provided for two years to practising veterinary surgeons, in which samples of serum were taken from dogs treated with either primidone or phenobarbitone. Of the 19 patients assessed, 13 were controlled after the recommended changes in dose had been made. Of the six patients not completely controlled after changes in dose, four had a much lower incidence of seizures but two did not respond to treatment in spite of having high serum phenobarbitone levels. There were large variations between the doses of anticonvulsant drugs required to reach therapeutic serum levels; these variations underlined the value of routine monitoring for improving the control of canine seizures.

A baiting system suitable for the delivery of oral rabies vaccine to dog populations in Zimbabwe.

Abstract: A baiting system suitable for the delivery of oral rabies vaccine to dog populations in developing countries was studied in Zimbabwe. In a field trial, 369 sponge baits containing a placebo liquid, rhodamine B as a biomarker and a pungent attractant were distributed over an area of 60 sq km in a communal land in Manicaland with a dog population of over 500. Twenty-four hours later 21 per cent of the baits were recovered and 79 per cent of these had been significantly bitten or chewed. Twenty-five per cent of the dogs examined showed evidence of superficial staining by rhodamine B indicating that they had chewed baits or ingested their contents. It was concluded that the system would deliver an oral vaccine to dog populations more efficiently than had been the case in comparable studies in wildlife populations, but that the number of baits per unit area should in future studies be increased.

Nocardiosis: a neglected chronic lung disease in Africa?

Abstract: Nocardia organisms were cultured from the sputum of 11 patients at the central hospitals in Harare, Zimbabwe, over a 12 month period. Pulmonary nocardiosis was diagnosed in one further patient on the basis of direct microscopy. Among the nine patients available for follow up, pulmonary nocardiosis was considered to be the major clinical problem in six. The patients usually presented with a chronic pulmonary infection with fever and cough without evidence of dissemination of underlying systemic disease. The chest radiograph showed consolidation in any part of the lung, and this was seen to extend slowly over several months. Prolonged diagnostic delay was a frequent problem. Haemoptysis, alcohol abuse, and empirical treatment for tuberculosis commonly featured in the history. Treatment with sulphonamides was generally successful in those patients who complied. Nocardiosis is a treatable lung disease that may be more common in developing countries than is currently recognised.

Patterns of visual—spatial performance and ‘spatial ability‘: Dissociation of ethnic and sex differences

Abstract: Is there a common basis for the ethnic and sex differences that are characteristically obtained on psychometric tests of spatial ability? Three experiments approached this question by observing subject differences in the recognition and reconstruction of visual-spatial displays. The pattern of performance on these experimental tasks was compared with that on a traditional spatial ability test. In the first experiment, two samples of 40 students, balanced for sex, from Zimbabwe and Scotland respectively, attempted a forced-choice recognition task for meaningful scenes. Both ethnic groups and both sexes showed equivalent performance. The same subjects then undertook a task involving the reproduction of an arrangement of blocks into two-dimensional plan and elevation views. On this task, involving spatial reorientation, the Zimbabweans made over three times as many errors as the Scots. In a third experiment the requirement for spatial reorientation was added to the original recognition task and this was performed by a further 40 subjects. A significant difference between ethnic groups now emerged and this effect covaried with spatial ability. Again, however, no sex difference was observed. The overall pattern of results points to spatial reorientation as a major factor in the cross-ethnic differences. The absence of a sex difference on the experimental tasks contrasts with its appearance in both samples on the spatial ability test and represents a puzzling obstacle to our current understanding. This dissociation of sex and ethnic differences provides evidence against the hypothesis that they stem from the same source.

Socioeconomic factors associated with child health and nutrition in peri‐urban Zimbabwe

Abstract: Relationships between the nutritional status of children and several dimensions of socioeconomic status were investigated during the rainy season for 277 children under 5 years of age. The study took place in Chitungwiza, a peri‐urban community in Zimbabwe in 1985, five years after its political independence. Three measures of nutrition — underweight, stunting and wasting — were used. Variation in nutritional status was explained principally by the socioeconomic status of parents which included education, occupation, income, and housing tenure. Other important factors were being born in modern health facilities, absence of disease, normal birth weight, expenditures on food, protein intake, and low crowding.

Hodgkin's disease in black Zimbabweans. A study of epidemiologic, histologic, and clinical features

Abstract: A 3-year prospective study of the histologic and clinical features of patients with Hodgkin's disease presenting to the medical units in Harare, Zimbabwe, was undertaken. The histologic pattern of disease was similar to that of other African countries with mixed cellularity and lymphocyte depleted patterns prevailing (58% and 21%, respectively). Unlike most African countries, however, disease occurred most commonly in teenagers and young adults. Nutritional status was poor in just under 50% of the patients. Clinically, the extent of disease at presentation was striking, with over 90% of patients having advanced stage disease in spite of the stated duration of symptoms being moderate. The histologic and clinical findings resembled those reported from other African countries, but in certain aspects the epidemiologic pattern was intermediate between those of affluent and underprivileged communities.

Transfer of Cognitive Academic Competence and L2 Reading in a Rural Zimbabwean Primary School

Abstract: Evidence for transfer of academic competence between Shona and English was examined to determine when instruction in L2 reading should begin for native Shona speakers. Third-, fourth-, and fifthgrade children attending a rural Zimbabwean primary school participated in the study. The children, who were receiving reading instruction both in Shona and in English, were randomly assigned to take one of four vocabulary tests. The tests, designed to examine the transfer of academic competence, measured the effects of language (Shona or English), translation (original or translation), and grade level. Analysis of the data indicated that with the exception of the fifth graders, there was little evidence of transfer of language skills between languages. The results suggest that these children might benefit from a delay in the introduction of L2 reading. The data are consistent with Cummins's (1985) transfer threshold hypothesis and may explain the inefficiency of L2 reading instruction. However, since the data reported in this study are drawn from a single case of a single rural primary school, the conclusions must be regarded as tentative and subject to replication.

Some Determinants of the Mating System in a Population of Painted Reed Frogs (Hyperolius Marmoratus)

Abstract: Hyperolius marmoratus shares its breeding site with 12 synchronously breeding species. Males call from elevated perches to attract females. Observations of captive populations suggest that males may adopt alternative mating strategies when chorus densities are high. Similar strategies were not observed in natural choruses. The operational sex ratio (OSR) was always male-biased and also highly variable. Mating was polygynous, only 25% of the male population actually mated. Females mated either once or twice. Variance in mating success was much greater among males, an obvious consequence of a skewed OSR. Female choice was probably not a causal factor because male mating success was correlated with neither size nor age. Size-based variation in the male advertisement call does exist, but females cannot exploit this potential vocal cue because of their impaired discriminatory ability in a complex sonic environment and the potential risk of mismating. Although the mating system may best be described as lek-like, with males forming organised choruses through competitive interactions, the variance in male mating success is probably a consequence of stochastic factors.

Parasites of the stomach in donkeys of the highveld of Zimbabwe

Abstract: Fourteen donkeys from a communal area of the Zimbabwean highveld were examined for stomach parasites during July and November of 1986 and January and April of 1987. All 14 animals were infected. Habronema muscae occurred in 12, Draschia megastoma in 11, H. majus in 9, Trichostrongylus axei in 9, Gasterophilus intestinalis in 14 and G. nasalis in 1 donkey. The lowest level of infection was in January for the helminths and in April for Gasterophilus larvae. The peak burdens of parasites were in July for Habronema spp. and in November for D. megastoma and Gasterophilus larvae. Infections with spirurid worms and Gasterophilus develop mainly from the middle of the rainy season to the beginning of the dry season (January to May/June). G. intestinalis seems to have an annual cycle.

A mark-recapture method for ecological studies of schistosomiasis vector snail populations.

Abstract: Mark—recapture methods have been used only sporadically in studies of the population biology of the snail vectors of schistosomiasis, yet mark—recapture has potential advantages for obtaining estimates of absolute abundance and recruitment and loss rates for snail populations in the field. A case study is described that uses Bailey's triple catch design to estimate these parameters for Bulinus globosus and Biomphalaria pfeifferi in a small river in Zimbabwe. The assumptions inherent in the design and tests of these assumptions are described. The parameter estimates obtained are biologically plausible, suggesting significant recruitment into the population at the time of the study and a life expectancy for B. globosus of about three weeks. The major drawback is the lack of precision of these estimates. Means of improving precision are discussed, and mark—recapture is evaluated as a research tool for the study of vector snail population biology.

The treatment of donovanosis (granuloma inguinale).

Abstract: Over a two-year period, 37 patients with genital ulcer disease attending a clinic for sexually transmitted diseases in Harare were found to have donovanosis. Of the 37 patients, 25 were male, and 12 were female; all presented with painless, indurated, granulating ulcers without lymph-node involvement. The lesions were more extensive in pregnant women. All patients responded well to either a combination of intramuscular streptomycin plus oral tetracycline given over 14 days, or a 14-day course of oral co-trimoxazole (trimethoprim-sulfamethoxazole). No metastatic lesions were found.

A preliminary assessment of the biomass of the pelagic sardine Limnothrissa miodon in Lake Kariba

Abstract: The sardine Limnothrissa miodon was very patchily distributed in Lake Kariba in 1981–1983 and its mean biomass was 59 23 kg ha−1, declining from 90–91 kg ha−1 in 1981 to 38–66 kg ha−1 in 1983. In addition, the mean size of the fish fell from 55–2 mm in 1981 to 49–9 mm in 1983. These changes are attributed to the effects of drought and reduced river flows as well as to the high level of commercial fishing for this species. There was a correlation between commercial catches and biomass estimates which allowed estimation of biomass in previous years from fishing statistics. Fishing effort appeared to be a major influence on sardine abundance: total biomass in 1985 was about 10% of what it was in 1974 when the fishery began. When expressed in terms of unit area, as is usual for African lakes, the pelagic biomass appeared to be greater in Lake Tanganyika, where Limnothrissa is endemic, than in Lake Kariba, although there is little difference in their primary productivity, but consideration in terms of volume rather than area shows that this was not the

The evolution of smallholder irrigation policy in Zimbabwe: 1928–1986

Abstract: Voluntary smallholder irrigation schemes in Zimbabwe were launched in 1913 as a means of famine relief and subsequently to settle black farmers displaced from designated areas for white commercial farmers. In 1928 the colonial government inaugurated a programme to provide services to existing smallholder schemes and to assist in developing new schemes. This process eventually led to the erosion of farmer participation in planning, development and financing of smallholder schemes. Since 1928 the smallholder schemes have been heavily subsidised, a pattern that continues today. Currently about 3.4% of the land under irrigation is farmed by small holders who pay about 11% of the costs of irrigation operation and maintenance; the remaining 89% is subsidised by the government. More smallholder irrigation development is currently being planned. The government has made loan funds available to groups on the basis of financial viability, but to date this fund has not been significantly utilized by smallholders. In essence, smallholder irrigation development is being constrained by problems that have plagued smallholder schemes since 1928.