Showing papers by "University of Zambia published in 2006"

Will African agriculture survive climate change

Abstract: Measurement of the likely magnitude of the economic impact of climate change on African agriculture has been a challenge. Using data from a survey of more than 9,000 farmers across 11 African countries, a cross-sectional approach estimates how farm net revenues are affected by climate change compared with current mean temperature. Revenues fall with warming for dryland crops (temperature elasticity of -1.9) and livestock (-5.4), whereas revenues rise for irrigated crops (elasticity of 0.5), which are located in relatively cool parts of Africa and are buffered by irrigation from the effects of warming. At first, warming has little net aggregate effect as the gains for irrigated crops offset the losses for dryland crops and livestock. Warming, however, will likely reduce dryland farm income immediately. The final effects will also depend on changes in precipitation, because revenues from all farm types increase with precipitation. Because irrigated farms are less sensitive to climate, where water is available, irrigation is a practical adaptation to climate change in Africa.

Prevalence of antibodies to Brucella spp. and individual risk factors of infection in traditional cattle, goats and sheep reared in livestock-wildlife interface areas of Zambia.

Abstract: Pre-print to the original published by SpringerLink accessible on: http://www.springerlink.com/content/8r11190t71tg0080/

Interactions of malnutrition and immune impairment, with specific reference to immunity against parasites

Abstract: KEY POINTS Clinical malnutrition is a heterogenous group of disorders including macronutrient deficiencies leading to body cell mass depletion and micronutrient deficiencies, and these often coexist with infectious and inflammatory processes and environmental problems. There is good evidence that specific micronutrients influence immunity, particularly zinc and vitamin A. Iron may have both beneficial and deleterious effects depending on circumstances. There is surprisingly slender good evidence that immunity to parasites is dependent on macronutrient intake or body composition. INTRODUCTION It is well recognized that the relationship between malnutrition and infection is an intimate one, and it is often assumed that this is because of impaired immune function. Management guidelines for treatment of malnutrition in children explicitly recognize that treatment of overt and occult infection is a first step in breaking the cycle of infection, malnutrition, and immune impairment. In this review, we shall explore one direction of this complex interaction by trying to answer the question ‘what is the effect of malnutrition on immunity?’ We will deal only with undernutrition, not with the immunological consequences of overnutrition. We must also point out that there are simply too few data to permit us to analyse the impact of each type of nutritional deficiency on the many pathways involved in immunity against parasites. Instead, we will try to draw broad conclusions from such information as does exist. We can restate the above question by considering some recent observations on the pathogenicity of two protozoa. In the course of a randomized controlled trial of the effect of an elemental diet on the outcome of severe diarrhoea–malnutrition in Zambian children (1), we submitted faecal samples for parasitological analysis at the beginning and at the end of the trial. For 1 month, 200 children were treated with either routine nutritional rehabilitation or an elemental diet (i.e. a diet in which all the macronutrients are broken down to amino acids, oligosaccharides and simple lipids). At the beginning of the trial all these children had persistent diarrhoea, which was an entry criterion. At the end of the trial all 161 survivors were free of diarrhoea. But the prevalence of pathogenic protozoa was only modestly reduced at the end of the trial compared to the baseline coprological analysis. Initially the prevalences of Cryptosporidium parvum and Giardia intestinalis were 24% and 6%, respectively, but after treatment they were 13% and 8%, respectively (M. Mwiya and S. Sianongo, unpubl. obs.). In other words, children with persistent diarrhoea who had had pathogens at the beginning of the trial became convalescent carriers. This recovery from diarrhoea was very likely to have been due to a nutritional intervention even though the protozoa were still present. There is very good evidence to attest to the fact that these species are pathogenic and in this and other studies C. parvum has been shown to be an independent predictor of mortality. We are led to conclude that improving nutrition restored some aspect of host defence, and this somehow improved the barrier function of the intestinal mucosa against potential pathogens. Thus, the expression of virulence is to some extent determined by host defences, and this can be modulated by nutritional status. So our question becomes three. First, what are the major immunological defects in malnutrition that might increase susceptibility to parasitic infection? Second, what is it in the immune response that improves on nutritional rehabilitation? Third, which nutrients are most important for any of these effects? We will begin with a sketch overview of immunity against parasites and what we mean by ‘malnutrition’, then consider these three questions in turn.

Marked HIV prevalence declines in higher educated young people: evidence from population-based surveys (1995-2003) in Zambia.

Abstract: Higher educational attainment has been associated with a greater risk of HIV infection in sub-Saharan Africa. We investigated change over time in HIV prevalence by educational attainment in the general population. The data stem from serial population-based HIV surveys conducted in selected urban and rural communities in 1995 (n = 2989) 1999 (n = 3506) and 2003 (n = 4442). Analyses were stratified by residence sex and age-group. Logistic regression was used to estimate age-adjusted odds ratio of HIV between low (= 4 school years) and higher education (= 8 years) for the rural population and between low (= 7 school years) and higher education (= 11 years) for the urban population. There was a universal shift towards reduced risk of HIV infection in groups with higher than lower education in both sexes among urban young people [odds ratio (OR) 0.20; 95% confidence interval (CI) 0.05-0.73] in men and (OR 0.33; 95% CI 0.15- 0.72) in women. A similar pattern was observed in rural young men (OR 0.17; 95% CI 0.05-0.59) but was less prominent and not statistically significant in rural women. In age 25-49 years higher educated urban men had reduced risk in 2003 (OR 0.43; 95%CI 0.26-0.72) but this was less prominent in women. The findings suggested a shift in the association between educational attainment and HIV infection between 1995 and 2003. The most convincing sign was the risk reduction among more educated younger groups where most infections can be assumed to be recent. The changes in older groups are probably largely influenced by differential mortality rates. The stable risk among groups with lower education might also indicate limitations in past preventive efforts. (authors)

Rapid Voluntary Testing and Counseling for HIV: Acceptability and Feasibility in Zambian Antenatal Care Clinics

Abstract: Voluntary testing and counseling (VTC) for HIV/AIDS is now widely accepted as an effective HIV prevention and control strategy among heterosexual couples in sub-Saharan Africa. The most appropriate format and venue for VTC remains a topic of debate among clinicians and public health professionals. Our research done in Lusaka, Zambia, took a tripartite approach to exploring the most acceptable format and venue for VTC: a community survey of attitudes towards VTC, a pre- and postcounseling knowledge survey, and a pilot study of same-day VTC in urban antenatal care clinics. A community survey of 181 individuals was conducted in July-August 1996 based on a structured questionnaire. A pre- and post-VTC intervention knowledge survey was conducted during the same period among 82 couples attending the Zambia-UAB HIV Research Project (ZUHRP) HIV VTC center in Lusaka. Finally, same-day HIV VTC was pilot tested in six antenatal clinic locations during February-May 1997 and June-August 1998. The community survey revealed that 98% of participants support promotion of HIV VTC in the community and 83.8% prefer the same-day testing format. The knowledge survey revealed misconceptions about discordance within a couple and perinatal transmission of HIV. Pilot testing in antenatal clinics was well received, with 84% of pregnant women requesting testing and 25% having positive HIV serologies. Women with primary school or less education, those seeking antenatal care in local clinics, and those seen before the third trimester of pregnancy were more likely to request HIV testing. Testing and counseling for HIV were shown to be feasible and effective in the antenatal clinic setting. Implementation of same-day HIV VTC in antenatal clinics is an effective strategy to prevent vertical transmission and should be expanded to include couples to leverage a decrease in heterosexual transmission as well.

Reducing stunting among children: the potential contribution of diagnostics

Abstract: The development of an inexpensive, simple and widely accessible test for diagnosing human immunodeficiency virus (HIV) infection in infants could significantly reduce paediatric acquired immunodeficiency syndrome (AIDS) deaths in sub-Saharan Africa.

Assessment of routine inspection methods for porcine cysticercosis in Zambian village pigs

Abstract: The value of tongue and meat inspection as diagnostic tools for porcine cysticercosis was assessed in 65 Zambian village pigs by comparing the results with carcass dissections. In addition, the intensity of infections, distribution and viability of cysts in infected pigs were measured. Five pigs (7.7%) were positive on tongue examination, while routine meat inspection showed 12 (18.5%) positives. However, carcass dissections detected cysticerci in 31 (47.7%) pigs. The range in number of cysticerci was 1 to 14,662 per carcass. Cysticerci were distributed throughout the carcass with the highest concentration in the heart, tongue and hind legs. In one animal 13 viable cysts were detected only in the brain. Fourteen pigs had more than 100 viable cysts, six between 2 and 100, and four had single cyst infections. Seven animals harboured only calcified cysts. These findings demonstrate the serious shortcomings of routine detection methods for porcine cysticercosis. While the specificity of tongue palpation and meat inspection was 100%, these tests failed to detect the infection in 83.9% and 61.3% of infected pigs, respectively.

Common conditions leading to cattle carcass and offal condemnations at 3 abattoirs in the Western Province of Zambia and their zoonotic implications to consumers

Abstract: From a total of 32 717 cattle slaughtered, 183 whole carcass condemnations were attributable to 9 diseases and conditions, namely, tuberculosis (TB), cysticercosis, emaciation, generalised lymphadenitis, jaundice, abscesses, moribund, sarcosporidiosis and odour. Bovine TB was the most important cause of condemnations (152 / 183, 83.1 %). Bovine cysticercosis and sarcosporidiosis accounted for 5 / 183 (2.7 %) and 8 / 183 (4.4 %), respectively, while each of the remaining conditions contributed less. Among the many conditions responsible for offal / organ condemnations were fascioliasis, contagious bovine pleuropneumonia, hydatidosis and TB. In terms of number and weight, Fasciola gigantica infections made livers and lungs the most condemned offals (20.1 % and 0.7 %, respectively). Hydatidosis was the cause of 0.9%lung and 0.1%liver losses. Cysticercus bovis contributed to only 0.05%of all inspected tongues, hearts, and heads.TB was very rare in heads (0.01 %). The financial impact of whole carcasses and offals condemned during the study period was enormous and deprived livestock farmers of the much needed revenue and consumers of protein sources. Much or all of the condemned material that could have been useful was wasted by not being retrieved for conversion to processed meat, bone meal or pet food. Failure to detect lesions of potential zoonotic diseases at slaughter poses a health risk to consumers especially when meat is eaten undercooked.

Reduction in preterm delivery and neonatal mortality after the introduction of antenatal cotrimoxazole prophylaxis among HIV-infected women with low CD4 cell counts.

Abstract: Cotrimoxazole prophylaxis is recommended for subgroups of human immunodeficiency virus (HIV)-infected adults and children to reduce all-cause morbidity and mortality. We investigated whether antenatal cotrimoxazole prophylaxis begun during pregnancy for HIV-infected pregnant women with low CD4 cell counts would affect birth outcomes. Cotrimoxazole prophylaxis was introduced as a routine component of antenatal care for HIV-infected women with CD4 cell counts < 200 cells/µL during the course of a trial of mother-to-child HIV transmission in Lusaka Zambia. Rates of preterm delivery low birth weight and neonatal mortality were compared for women with low CD4 cell counts before and after its introduction. Among 255 women with CD4 cell counts < 200 cells/µL the percentage of preterm births (= 34 weeks of gestation) was lower (odds ratio [OR] 0.49 [95% confidence interval {CI} 0.24-0.98]) after cotrimoxazole prophylaxis was introduced than before; there was a significant decrease in neonatal mortality (9% to 0%; P = .01) and a trend toward increased birth weight (b = 114 g [95% CI -42 to 271 g]). In contrast there were no significant changes in these parameters over the same time interval among women with CD4 cell counts = 200 cells/µL. Antenatal provision of cotrimoxazole for HIV-infected pregnant women with low CD4 cell counts may have indirect benefits for neonatal health. (authors)

Late Holocene linkages between decade–century scale climate variability and productivity at Lake Tanganyika, Africa

Abstract: Microlaminated sediment cores from the Kalya slope region of Lake Tanganyika pro- vide a near-annually resolved paleoclimate record between ~2,840 and 1,420 cal. yr B.P. demon- strating strong linkages between climate vari- ability and lacustrine productivity. Laminae couplets comprise dark, terrigenous-dominated half couplets, interpreted as low density under- flows deposited from riverine sources during the rainy season, alternating with light, planktonic diatomaceous ooze, with little terrigenous com- ponent, interpreted as windy/dry season deposits. Laminated portions of the studied cores consist of conspicuous dark and light colored bundles of laminae couplets. Light and dark bundles alter- nate at decadal time scales. Within dark bundles, both light and dark half couplets are significantly thinner than within light bundles, implying slower sediment accumulation rates during both seasons over those intervals. Time series analyses of laminae thickness patterns demonstrate significant periodicities at interannual-centennial time scales. Longer time scale periodicities (multidecadal to centennial scale) of light and dark half couplet thicknesses are coherent and in some cases are similar to solar cycle periods on these time scales. Although laminae thickness cycles do not strongly covary with the actual D 14 C record for this same time period, two large D 14 C anomalies are associated with substantial decreases in both light and dark laminae thickness. In contrast to the multidecadal-

Steep HIV prevalence declines among young people in selected Zambian communities: population-based observations (1995-2003).

Abstract: Understanding the epidemiological HIV context is critical in building effective setting-specific preventive strategies. We examined HIV prevalence patterns in selected communities of men and women aged 15–59 years in Zambia. Population-based HIV surveys in 1995 (n = 3158), 1999 (n = 3731) and 2003 (n = 4751) were conducted in selected communities using probability proportional to size stratified random-cluster sampling. Multivariate logistic regression and trend analyses were stratified by residence, sex and age group. Absence, <30% in men and <15% in women in all rounds, was the most important cause of non-response. Saliva was used for HIV testing, and refusal was <10%. Among rural groups aged 15–24 years, prevalence declined by 59.2% (15.7% to 6.4%, P < 0.001) in females and by 44.6% (5.6% to 3.1%, P < 0.001) in males. In age-group 15–49 years, declines were less than 25%. In the urban groups aged 15–24, prevalence declined by 47% (23.4% to 12.4%, P < 0.001) among females and 57.3% (7.5% to 3.2%, P = 0.001) among males but were 32% and 27% in men and women aged 15–49, respectively. Higher educated young people in 2003 had lower odds of infection than in 1995 in both urban [men: AOR 0.29(95%CI 0.14–0.60); women: AOR 0.38(95%CI 0.19–0.79)] and rural groups [men: AOR 0.16(95%CI 0.11–0.25), women: AOR 0.10(95%CI 0.01–7.34)]. Although higher mobility was associated with increased likelihood of infection in men overall, AOR, 1.71(95%CI 1.34–2.19), prevalence declined in mobile groups also (OR 0.52 95%CI 0.31–0.88). In parallel, urban young people with ≥11 school years were more likely to use condoms during the last casual sex (OR 2.96 95%CI 1.93–4.52) and report less number of casual sexual partners (AOR 0.33 95%CI 0.19–0.56) in the last twelve months than lower educated groups. Steep HIV prevalence declines in young people, suggesting continuing declining incidence, were masked by modest overall declines. The concentration of declines in higher educated groups suggests a plausible association with behavioural change.

Responses to tuberculin among Zebu cattle in the transhumance regions of Karamoja and Nakasongola district of Uganda

Abstract: Responses to tuberculin in Zebu cattle of the transhumant pastoral farming system in Karamoja region and Nakasongola district in the north-eastern and mid-central regions in Uganda, respectively, were investigated using a comparative intradermal tuberculin skin test. Of the 1864 cattle tested from 30 large units (superherds) in Karamoja and 7 herds in Nakasongola, a total of 28 animals from 19 herds (51.4%) tested positive. Inter-district tuberculin reactor prevalence variations seemed to be influenced by climate, with impact on both the management patterns and transmissibility of agent. High herd tuberculin reactor prevalence (51.4%) was attributed to widespread contacts and mixing of animals between herds. Low individual animal tuberculin test positivity (mean = 1.4%) was attributed to low transmissibility of the agent under the Karamoja climate, which is semi-arid, and to increased resistance due to non-specific response to environmental mycobacteria and natural selection, since there was no active control against bovine tuberculosis. Owing to similarities in management practices in Karamoja and widespread risk factors, it was difficult to identify which were more important, but variations in sources of drinking water pointed to provision of lake and borehole water during dry season as reducing the risk. Positive bovine tuberculin reactor prevalence and skin reactor status were related to age.

Can biomedical and traditional health care providers work together? Zambian practitioners' experiences and attitudes towards collaboration in relation to STIs and HIV/AIDS care: a cross-sectional study

Abstract: Background: The World Health Organization's World health report 2006: Working together for health underscores the importance of human resources for health. The shortage of trained health professionals is among the main obstacles to strengthening low-income countries' health systems and to scaling up HIV/AIDS control efforts. Traditional health practitioners are increasingly depicted as key resources to HIV/AIDS prevention and care. An appropriate and effective response to the HIV/AIDS crisis requires reconsideration of the collaboration between traditional and biomedical health providers (THPs and BHPs). The aim of this paper is to explore biomedical and traditional health practitioners' experiences of and attitudes towards collaboration and to identify obstacles and potential opportunities for them to collaborate regarding care for patients with sexually transmitted infections (STIs) and HIV/AIDS. Methods: We conducted a cross-sectional study in two Zambian urban sites, using structured questionnaires. We interviewed 152 biomedical health practitioners (BHPs) and 144 traditional health practitioners (THPs) who reported attending to patients with STIs and HIV/AIDS.

Factors associated with HIV prevalence in a pre-partum cohort of Zambian women:

Abstract: An ongoing study of mother-to-child human herpes virus-8 (HHV-8) transmission in Zambian women (n = 3160) allowed us to examine the association of medical injections with HIV serostatus while simultaneously accounting for other factors known to be correlated with HIV prevalence. Multi-method data collection included structured interviews, medical record abstraction, clinical examinations, and biological measures. Medically administered intramuscular or intravenous injections in the past five years (but not blood transfusions) were overwhelmingly correlated with HIV prevalence, exceeding the contribution of sexual behaviours in a multivariable logistic regression. Statistically significant associations with HIV also were found for some demographic variables, sexual behaviours, alcohol use, and sexually transmitted diseases (STD). The results confirmed that iatrogenic needle exposure, sexual behaviour, demographic factors, substance use, and STD history are all implicated in Zambian women's HIV+ status. However, the disproportionate association of medical injection history with HIV highlights the need to investigate further and prospectively the role of health-care injection in sub-Saharan Africa's HIV epidemic.

Antenatal clinic-based HIV prevalence in Zambia: declining trends but sharp local contrasts in young women.

Abstract: OBJECTIVES To describe regional variation in human immunodefffeciency virus (HIV) prevalence trends in the period 1994-2002 and to assess the effects on prevalence trends of residence, educational level and age, and potential interaction between these variables. METHODS The data were from the national HIV sentinel surveillance system comprising information collected using interviews and unlinked anonymous testing of blood among pregnant women attending antenatal clinics in 22 sites in 1994, 1998 and 2002. RESULTS There was a decline in HIV prevalence in the age group 15-24 years in the period 1994-2002 both in rural (by 11%) and urban (by 26%) areas. The decline was strongest among highly educated women. However, this overall decline masked striking differences at community (site) levels with clearly declining epidemics in many sites contrasted by increasing epidemics in some and stability in others. Urban/rural residence, age, educational attainment, marital status and parity were factors closely associated with HIV infection. Having born many children was associated with lower risk of being infected by HIV, even in the age group 15-24. CONCLUSIONS The HIV prevalence decline in young women is likely to reflect a drop in incidence during the period. However, there were sharp geographical contrasts in trends. Such local contrasts probably indicate differences in effectiveness of preventive interventions. Understanding factors and mechanisms explaining the differences will be of critical importance to better guide preventive interventions.

Efficient Management of Health Centres Human Resources in Zambia

Abstract: This study uses Data Envelopment Analysis (DEA) to estimate the degree of technical, allocative and cost efficiency in individual public and private health centres in Zambia; and to identify the relative inefficiencies in the use of various inputs among individual health centers. About 83% of the 40 health centres were technically inefficient; and 88% of them were both allocatively and cost inefficient. The privately owned health centers were found to be more efficient than public facilities.

Risk factors for subclinical mastitis among HIV-infected and uninfected women in Lusaka, Zambia.

Abstract: Subclinical mastitis, defined as raised milk sodium/potassium (Na/K) ratio, is associated with poor infant growth and, among HIV-infected women, with increased milk HIV viral load We conducted a longitudinal cohort study in Lusaka, Zambia, in order to investigate the relative importance of several potential causes of subclinical mastitis: maternal infection, micronutrient deficiencies and poor lactation practice Women (198 HIV-infected, 189 HIV-uninfected) were recruited at 34 weeks' gestation and followed up to 16 weeks postpartum for collection of information on their health, their infant's health, infant growth and infant feeding practices Milk samples were collected from each breast at 11 postpartum visits and blood at recruitment and 6 weeks postpartum The geometric mean milk Na/K ratio and the proportion of women with Na/K ratio > 10 in one or both breasts were significantly higher among HIV-infected than among uninfected women Other factors associated with the higher mean Na/K ratio in univariable analyses were primiparity, high maternal alpha(1)-acid glycoprotein (AGP) at 6 weeks, maternal overall morbidity and specific breast symptoms, preterm delivery, low infant weight or length, infant thrush and non-exclusive breast feeding In multivariable analyses, primiparity, preterm delivery, breast symptoms, HIV status and raised AGP were associated with the raised Na/K ratio Thus the main factors associated with subclinical mastitis that are amenable to intervention are poor maternal overall health and breast health The impact of improved postpartum health care, especially management of maternal infections and especially in primiparous women, on the prevalence of subclinical mastitis and its consequences requires investigation