Removal of Arsenic (V) from Aqueous Solutions Using Chitosan-Red Scoria and Chitosan-Pumice Blends.

In different regions across the globe, elevated arsenic contents in the groundwater constitute a major health problem. In this work, a biopolymer chitosan has been blended with volcanic rocks (red scoria and pumice) for arsenic (V) removal. The effect of three blending ratios of chitosan and volcanic rocks (1:2, 1:5 and 1:10) on arsenic removal has been studied. The optimal blending ratio was 1:5 (chitosan: volcanic rocks) with maximum adsorption capacity of 0.72 mg/g and 0.71 mg/g for chitosan: red scoria (Ch-Rs) and chitosan: pumice (Ch-Pu), respectively. The experimental adsorption data fitted well a Langmuir isotherm (R² > 0.99) and followed pseudo-second-order kinetics. The high stability of the materials and their high arsenic (V) removal efficiency (~93%) in a wide pH range (4 to 10) are useful for real field applications. Moreover, the blends could be regenerated using 0.05 M NaOH and used for several cycles without losing their original arsenic removal efficiency. The results of the study demonstrate that chitosan-volcanic rock blends should be further explored as a potential sustainable solution for removal of arsenic (V) from water.

Adsorption of As(III) versus As(V) from aqueous solutions by cerium-loaded volcanic rocks.

Contamination of drinking water with arsenic causes severe health problems in various world regions. Arsenic exists predominantly as As(III) and As(V) depending on the prevailing redox conditions of the environment. Most of the techniques developed for treating As(V) are not very effective for As(III), which is more toxic and mobile than As(V). In this study, novel cerium-loaded pumice (Ce-Pu) and red scoria (Ce-Rs) adsorbents were developed to remove both As(III) and As(V) ions from water. The Ce-Pu and Ce-Rs adsorbents were characterized using ICP-OES, EDX, and SEM. The experimental equilibrium sorption data fitted well Freundlich and Dubinin-Radushkevich (D-R) isotherms. The adsorption was very fast and reached an equilibrium within 2 h. Both Ce-Rs and Ce-Pu showed high As(III) and As(V) removal efficiency in a wide pH range between 3 and 9, which is an important asset for practical applications. The Ce-Pu and Ce-Rs adsorbents can be recycled and used up to three adsorption cycles without significant loss of their original efficiency. Accordingly, Ce-Pu and Ce-Rs seem to be suitable for removal of arsenic from aqueous systems.

Elevated blood lead levels among unskilled construction workers in Jimma, Ethiopia.

BACKGROUND: No study has been carried out to assess the blood lead levels of workers or the contribution of common workplace practices to lead exposure in Ethiopia. This study was carried out to assess the blood lead levels of female and male laborers in the construction sector in Jimma town, Ethiopia. METHOD: A cross-sectional study on the blood lead levels of 45 construction workers was carried out in the town of Jimma. The t-test, analysis of variance, the Kruskal-Wallis, Mann-Whitney and odds ratio tests were used to compare mean blood lead levels and to investigate the associations between specific job type, use of self-protection device, sex, service years and occurrence of non-specific symptoms with BLLs. RESULTS: The mean blood lead level of the exposed group (40.03 ± 10.41 µg/dL) was found to be significantly greater than that of the unexposed group (29.81 ± 10.21 µg/dL), p = 0.05. Among the exposed group female workers were found to have higher mean blood lead level (42.04 ± 4.11 µg/dL) than their male colleagues (33.99 ± 3.28 µg/dL). Laborers who were regularly using self-protection devices were found to have significantly lower blood lead levels than those who were not using. CONCLUSION: The blood lead levels of construction workers in Jimma town are considerably high with a range of 20.46 - 70.46 µg/dL and the workers are in danger of imminent lead toxicity. More endangered are female construction workers who are bearers of the future children of the country and the issue requires urgent attention.

Calcium, magnesium, iron, zinc and copper, compositions of human milk from populations with cereal and 'enset' based diets.

BACKGROUND: As breast milk is normally the only source of food in the early stages of life, the dietary levels of the essential elements in the milk of lactating mothers are significantly important. Ethiopia is a country of many nations and nationalities with distinct dietary habits. This variation in food habit may result in the variation of the nutritional quality of milk of lactating mothers who live in different part of the country, which in turn may affect the intake of nutrients by breast-fed infants. Therefore, a cross-sectional study of the levels of Ca, Mg, Fe, Zn and Cu in milk of mothers from societies with cereal and 'enset' based dietary habits was carried out to assess the influence of maternal diet on the levels of the elements in human milk. METHODS: Milk samples were collected from 27 voluntary mothers in Jimma and in 18 rural areas of Welkite. Breast milk samples were collected within four days postpartum and the concentrations of the elements were determined by using FAAS. RESULTS: Average concentrations (mg/L) of the elements determined in the milk of mothers from Jimma and rural Welkite respectively were: Ca (758 ± 107, 579 ± 168); Mg (22.6 ± 7.87, 30.5 ± 13.4); Fe (0.50 ± 0.08, 0.41 ± 0.17); Zn (2.3 ± 1.2, 2.49 ± 0.88) and Cu (0.28 ± 0.14, 0.16 ± 0.08). CONCLUSIONS: Milk samples from Jimma were found to have significantly higher levels of Ca and Cu than those of rural Welkite (P < 0.05). Breast milk Ca and Cu levels were thus found to be influenced by dietary intake.

Analysis of organochlorine pesticide residues in human and cow's milk in the towns of Asendabo, Serbo and Jimma in South-Western Ethiopia.

The level of some OCPs in human and cow milk collected from Asendabo, Serbo and Jimma in South-West Ethiopia were analyzed using GC-ECD. Results of the analysis indicated that all samples contained detectable quantities of p,p'-DDT and its metabolites, p,p-DDE and p,p-DDD, but none of the other OCPs analyzed. Mean levels of total DDT in the human and cow milk samples in the three areas were 12.68 and 0.389 µg g(-1) respectively. The distributions of p,p-DDT, p,p-DDE and p,p-DDD in the human milk samples from the three locations followed the same trend in which the proportion of p,p-DDT was the highest in all the three cases, comprising 55-71% of total DDT, followed by p,p-DDE, 26-39%, and the least, p,p-DDD of 2-5%. The mean ratio of DDT/DDE concentration for the three areas was calculated to be 2.01. This value was much higher than the values reported from other countries in earlier studies and indicates the existence of a higher quantity of DDT from a fresh input in the three study areas. The mean estimated daily intake of DDT by infants from mother's milk in the three locations was found to be 62.17 µg kg(-1) body weight, which is about three times higher than the acceptable daily intake set by WHO/FAO for total DDT, 20 µg kg(-1) of body weight. This alarmingly high daily intake value is a cause for concern, since children are highly susceptible to effects from such environmental contaminants. The study has revealed that people in the study areas are facing exposure to DDT from recent use. The observed contamination of mother's milk and the possible transfer of the contaminant from mother to child is an obvious risk associated with breast-feeding in the study areas and possibly in other parts of the country too.

Occupational lead exposure among automotive garage workers - a case study for Jimma town, Ethiopia.

BACKGROUND: In Ethiopia, although there are numerous small-scale and medium industries which use lead-based raw materials that may pose health risks to workers, there are no workplace regulations for lead exposure. Moreover, there are no studies carried out on the blood lead levels (BLLs) of workers or on the contribution of common workplace practices to lead poisoning. METHOD: A cross-sectional study on the BLLs of 45 automotive garage workers and 40 non-garage workers was carried out in the town of Jimma, Ethiopia. In addition to BLL analysis, data on some risk factors such as smoking, and chewing 'khat' (the leaves of Catha adulis) were gathered through structured questionnaires and interviews and data analysis was performed using SPSS (version 16). The t-test was used to compare mean BLLs of study groups. The analysis of variance (ANOVA), Kruskal-Wallis, Pearson chi-square and odds ratio tests were used to investigate the associations between specific job type, smoking and/or 'khat' chewing, service years and occurrence of non-specific symptoms with BLLs. RESULTS: The mean BLL of the automotive-garage workers was found to be significantly greater than that of the controls. The BLLs of all the lead-exposed individuals were found to be over 10 µg/dL, and 53% of them had BLLs ranging 12 - 20 µg/dL, with the remaining 47% having over 20 µg/dL. The BLL of the workers increased with the duration of working in an automotive garage.Individuals involved in manual car painting comprise a larger percentage (58%) of those with the highest BLLs (≥ 20 µg/dL). Lead accumulation in individuals who chew 'khat' in the work place was found to be faster than in those who are not used to chewing 'khat'. 'Khat' is an evergreen shrub native to tropical East Africa, with dark green opposite leaves which are chewed when fresh for their stimulating effects. CONCLUSION: The findings of the study have clearly demonstrated that the BLLs of automotive-garage workers in Jimma town are considerably high with a range of 11.73 - 36.52 µg/dL and the workers are in danger of impending lead toxicity. The BLLs of the workers are influenced by their occupational practices, chewing Catha adulis leaves at the workplace, and the time spent working in an automotive garage.

Exposure and health risk assessment of applicators to DDT during indoor residual spraying in malaria vector control program.

We assessed exposure of applicators, health risk of DDT to the applicators and evaluated the applicability of existing pesticide exposure models for indoor residual spraying (IRS). Patch sampling for dermal and personal air sampler for inhalation exposure were used in monitoring 57 applicators on the exposure assessment to DDT. The exposure of the applicators was also estimated using three exposure models. The mean actual dermal exposure was 449 mg total DDT per applicator per one house treatment. The applicators were exposed to DDT much beyond the estimated AOEL (acceptable operator exposure level) of DDT. The exposure estimated with ConsExpo 5.0 b01 model is situated between the median and the 75th percentile of the experimental data. On the other hand, spraying model 1 and spraying model 10 overestimate the exposure. Thus, these three models cannot be directly used for the particular circumstances of IRS as a tool for risk assessment. In general, use of DDT in IRS as a control method for malaria mosquitoes holds a high health risk for the applicators. Strict implementation of spraying procedures stated in the IRS manual of World Health Organization (WHO) is necessary to reduce the exposure level and health risk of applicators to DDT.

Multiple insecticide resistance: an impediment to insecticide-based malaria vector control program.

BACKGROUND: Indoor Residual Spraying (IRS), insecticide-treated nets (ITNs) and long-lasting insecticidal nets (LLINs) are key components in malaria prevention and control strategy. However, the development of resistance by mosquitoes to insecticides recommended for IRS and/or ITNs/LLINs would affect insecticide-based malaria vector control. We assessed the susceptibility levels of Anopheles arabiensis to insecticides used in malaria control, characterized basic mechanisms underlying resistance, and evaluated the role of public health use of insecticides in resistance selection. METHODOLOGY/PRINCIPAL FINDINGS: Susceptibility status of An. arabiensis was assessed using WHO bioassay tests to DDT, permethrin, deltamethrin, malathion and propoxur in Ethiopia from August to September 2009. Mosquito specimens were screened for knockdown resistance (kdr) and insensitive acetylcholinesterase (ace-1(R)) mutations using AS-PCR and PCR-RFLP, respectively. DDT residues level in soil from human dwellings and the surrounding environment were determined by Gas Chromatography with Electron Capture Detector. An. arabiensis was resistant to DDT, permethrin, deltamethrin and malathion, but susceptible to propoxur. The West African kdr allele was found in 280 specimens out of 284 with a frequency ranged from 95% to 100%. Ace-1(R) mutation was not detected in all specimens scored for the allele. Moreover, DDT residues were found in soil samples from human dwellings but not in the surrounding environment. CONCLUSION: The observed multiple-resistance coupled with the occurrence of high kdr frequency in populations of An. arabiensis could profoundly affect the malaria vector control programme in Ethiopia. This needs an urgent call for implementing rational resistance management strategies and integrated vector control intervention.

Levels of Outpatient Satisfaction at Selected Health Facilities in Six Regions of Ethiopia

Background: Satisfaction is one of the meaningful indicators of patient experience of health care services. Asking patients what they think about the care and treatment they have received is an important step towards improving the quality of care; and to ensuring that local health services are meeting patients' needs. Various studies have reported that satisfied patients are more likely to utilize health services; comply with medical treatment; and continue with the health care provider. Objective: to assess and estimate the perceived levels of satisfaction with health services rendered at government health facilities in selected regions of Ethiopia. Methods: A cross-sectional study that involved an exit interview was conducted in purposively selected government health centers and general hospitals in six regions of Ethiopia. Data were collected using structured questionnaire between June and September 2004. Variables used in the study were grouped and summarized into three components; namely providers' characteristics; services characteristics and cleanliness of the health facilities. Each variable was scored on a 5 point Likert-like scale; ranging from 1 (very dissatisfied) to 5 (very satisfied). The mean score 2.5 is considered as a cut-off point and scores equal and above 2.5 are taken as an indicator of users' perceived satisfaction. Both bivariate and multivariate methods of data analyses were used as deemed necessary. Results: All the three components of investigated variables have reliability coefficients ranging from 0.57 to 0.82. Results of bivariate analyses depicted that the percentage for high mean score satisfaction with health providers' characteristics ranged from 77.25to 93.23; with service characteristics 68.64to 86.48; and satisfaction with cleanliness ranged from 76.50to 90.57. Results of multivariate analysis showed that relatively more explanatory variables were found to be significant ininfluencing cleanliness (cleanliness of waiting place; examination room and medical equipment). Most of the explanatory variables in service characteristics were not statistically significant as compared to other components. Conclusion: The investigators believe that improved service delivery in health facilities could be achieved by to proper and sustainable implementation of the newly initiated civil service reform program in civil service institutionsin the country. Furthermore; periodic assessment of health services and further study; especially from the user's satisfaction perspective is recommended as a fundamental initiative in the improvement of the performance of health facilities

Seroepidemiology of hepatitis B virus in Addis Ababa, Ethiopia: transmission patterns and vaccine control.

A community-based seroepidemiological survey of Addis Ababa, Ethiopia was conducted in 1994 to inform on the transmission dynamics and control of hepatitis B virus (HBV) infection. Venous blood from 4736 individuals under 50 years of age from 1262 households, selected using stratified cluster-sampling, was screened for HBV markers using commercial ELISAs. HBsAg prevalence was 7% (95 % CI 6-8), higher in males (9%; 7-10) than females (5%; 4-6). HBeAg prevalence in HBsAg positives was 23% (18-29), and less than 1% of women of childbearing age were HBeAg positive. Overall HBV seroprevalence (any marker), rose steadily with age to over 70% in 40-49 year olds, indicating significant childhood and adult transmission. Estimated instantaneous incidence was 3-4/100 susceptibles/year, higher in males than females in 0-4 year olds, and peaking in early childhood and young adults. The age at which 50% had evidence of infection was around 20 years, and the herd immunity threshold is approximated at 63-77%. Addis Ababa is of intermediate-high HBV endemicity, with negligible perinatal transmission. Our main findings are the identification of a significant difference between males and females in the age-acquisition of HBV infection, and marked differences between age groups in HBV incidence rates. These results should target future research studies of underlying risk factors. Furthermore, we generate a crude estimate of the level of coverage of HBV vaccine that would be required to eliminate the virus from the study population.

Seroepidemiology of measles in Addis Ababa, Ethiopia: implications for control through vaccination.

We undertook a representative survey of measles antibodies in Addis Ababa, Ethiopia 1994, to characterize immunity and transmission. Specific-antibody levels (IU/l) were determined by ELISA for 4654 sera from individuals aged 0-49 years (1805 < 15 years) collected by stratified household-cluster sampling. The proportion seronegative (< 100 IU/l) was 20% (95% CI: 16-25) in children 9-59 months old, declining to 9% (7-12) in 5-9 year olds, 5% (4-7) in 10-14 year olds, and < 1% in adults. The proportion of children (< 15 years old) with low-level antibody (100-255 IU/l) was 8% (7-10). Vaccination and an absence of a history of measles illness were strongly associated with low-level antibody. History of measles vaccination in 9 months to 14-year-old children was approximately 80%. We estimate a primary vaccine failure rate of 21% (12-34) and continued high measles incidence of 22 per 100 susceptibles (19-24) per annum. Our data support the introduction of campaign vaccination in the city in 1998, although higher routine vaccine coverage is required to sustain the impact. The implications of a high prevalence of low-level antibody are discussed.

Attitude and social consequences of tuberculosis in Addis Ababa, Ethiopia.

OBJECTIVE: To gain a better understanding of the attitude and social consequences of tuberculosis (TB) in Addis Ababa, Ethiopia. DESIGN: A cross sectional survey using a structured questionnaire and a qualitative study based on the focus group discussion (FGD) technique. SETTING: Eight different kebeles (urban dwellers' associations) of six woredas (next higher administrative level to kebele). SUBJECTS AND METHODS: Seven hundred and three participants, comprising 326 males and 377 females were interviewed using the written questionnaire and 36 recent and current TB patients through focus group discussion. Data were analysed using SPSS/PC statistical package. The proportions were compared using univariate and bivariate analyses to show the frequency distribution and evaluate the relationship among different variables. In FGD, topics relevant to the research questions were identified, sorted and analysed. Conclusions were then formulated. MAIN OUTCOME MEASURES: Attitude of participants towards TB and its victims and social consequences of being a TB patient. RESULTS: Eighty three per cent of the respondents were aware that TB is a disease transmitted from one person to another and 80.1% perceived TB as an extremely severe disease. Of the total, 81.5% answered that TB is caused by cold, 69.0% feel that TB patients are not accepted in the community and 78.3% fear physical contact with TB patients. Most participants of the FGD sessions agreed that TB is a very dangerous, contagious but curable disease and the community has a generally negative attitude towards them. They also think that TB is associated with HIV/AIDS in the society. These attitudes have social consequences particularly the stigmatization and social isolation of TB patients. Four hundred and four (57.5%) respondents were found to be in favour of the short course chemotherapy against 226 (32.1%) choosing the longer course. Clinical improvement and unavailability of some drugs or their cost were the first and second main reasons indicated, respectively, for defaulting by respondents. CONCLUSION: The perception by most respondents that tuberculosis is incurable, transmittable and associated with HIV/AIDS, led to the understanding that TB is a very dangerous disease. This, in turn, contributes to social avoidance and the resultant consequences in TB patients. Health education must be stepped-up within the TB control programme, and the psychosocial implications of TB should be given due attention.

The cost of integrating hepatitis B virus vaccine into national immunization programmes: a case study from Addis Ababa.

National programmes of hepatitis B virus (HBV) vaccination are recommended by the World Health Organization for all countries. Countries suffering the highest burden of HBV disease are those most needy of universal vaccination, but are frequently of very low income and resources for health care are scarce. The introduction of HBV vaccination would inevitably stretch these resources further even with support of donor agencies. Thus an assessment of the cost-effectiveness of HBV vaccination is desirable to assist in decision making about resource allocation. We describe here a method for estimating the additional costs of introducing HBV vaccination into the Expanded Programme on Immunization (EPI) at a national level. Of fundamental importance is that this method enables costs to be assessed prior to the introduction of vaccination. We illustrate the method using a study carried out at the sub-national level, in the city of Addis Ababa, Ethiopia, but which can be expanded countrywide. The method, in brief, involved the use of a number of questionnaires which could be used to estimate the costs associated with the EPI programme from a large sample of the static clinics as well as from central sources. Since unit costs were collected along with the quantities of resources used and estimates of the capacity used for certain facilities (such as refrigerators), the additional cost of introducing HBV vaccine could be estimated largely by extrapolation of the resources used in vaccinating against diphtheria/pertussis/tetanus vaccine (which, similar to HBV vaccine, requires three doses). The estimation of costs is only part of the information required to make decisions on resource allocation, and should be used in association with measures of the burden of disease due to the infection in the community and effectiveness of the control programme at reducing this burden. The prediction of the latter, based upon a sound epidemiological understanding of the infection, is the subject of a forthcoming paper.

Sero-epidemiology of rubella in the urban population of Addis Ababa, Ethiopia.

We conducted a community-based cluster sample survey of rubella sero-epidemiology in Addis Ababa, Ethiopia in 1994. Among 4666 individuals for whom complete data were available, rubella antibody prevalence was 91% (95% confidence interval: 90, 92). On multivariable analysis, seroprevalence was lower among individuals who were resident in Addis Ababa for 1 year or less. Approx. 50% seroprevalence was attained by age 4 years, and the estimated average age at infection was 5.2 years. The highest age-specific force of infection was estimated to occur in 5- to 9-year-olds. The early age at infection corresponded with a low estimated incidence of congenital rubella syndrome (CRS) of 0.3 per 1000 live births, equivalent to nine cases of CRS in 1994. The predicted critical level of immunity for elimination of rubella via vaccination was 85-91%, requiring 89-96% coverage with a vaccine of 95% effectiveness. Unless very high coverage of rubella vaccine could be guaranteed, the introduction of childhood vaccination could increase the incidence of CRS in Addis Ababa.

Prevalence of bacterial pathogens in children with acute respiratory infection in Addis Ababa.

A study was conducted in the Ethio-Swedish Children's Hospital and different schools and kindergartens in Addis Ababa to determine the prevalence of bacterial agents that are associated with acute respiratory infection in children from 1998-1999. A total of 883 subjects were studied, out of which 77% were cases from the Ethio-Swedish Children's Hospital and 23% were controls from different schools and kindergartens. From each case and control throat and nasopharyngeal specimens were collected. Culture and different biochemical tests were used to isolate the potential bacterial pathogens. Clinical findings like cough, difficult breathing and fever were correlated with laboratory findings. S. pneumoniae and H. influenzae type b were the most commonly isolated bacteria in both throat and nasopharyngeal specimens; 74% and 70% in the cases and 2% and 5% in the control groups, respectively. This paper discusses the association between throat and nasopharyngeal carriership of bacteria and acute respiratory infection in children in Addis Ababa.

A comparison of oral fluid and serum for the detection of rubella-specific antibodies in a community study in Addis Ababa, Ethiopia.

OBJECTIVE: To assess the utility of oral fluid compared with serum for the determination of age-prevalence of rubella-specific antibodies in an urban African community setting. METHOD: Paired serum and oral fluid samples were collected from 439 individuals aged 0-49 years in Addis Ababa, Ethiopia, as part of a larger seroepidemiological survey in 1994. Oral fluid was sampled using a simple sponge device that was well accepted by subjects of all ages; venous blood was collected by Vacutainer system. We measured rubella-specific antibodies in serum by the Radial Haemolysis (RH) test, supported by two confirmatory assays, and in oral fluid by IgG antibody-capture radioimmunoassay (GACRIA). RESULTS: Sensitivity and specificity of oral fluid results compared to serum were 89% and 76%, respectively. Sensitivity declined from 96% in age group 0-19 years to 90% in age group 20-29 and 78% in age group 30-49. Specificity was 86% in 0-9 year olds contrasting with 61% in older groups (10-49 years). The positive predictive value of an oral fluid sample was high in all age groups (range 92-100%), while the negative predictive value declined from > or =80% in those aged <10 years to <10% in those aged > or =30 years. Serum confirmatory tests suggested a proportion of false serum RH negatives, increasing with age, indicating a need to standardize serum as well as oral fluid tests. CONCLUSION: In the community setting of a developing country, oral fluid surveys could be useful to estimate age-prevalence of rubella immunity and identify rubella-susceptible children for follow-up. Further work is required to simplify assays and sample processing, improve assay sensitivity and estimate assay specificity more precisely, and compare and standardise collection methods suitable for surveillance of a variety of childhood viral infections.

Age- and sex-specific HIV-1 prevalence in the urban community setting of Addis Ababa, Ethiopia.

OBJECTIVE: To estimate the age and sex-specific prevalence of HIV infection in the population of Addis Ababa, Ethiopia. DESIGN: Two-stage cluster sampling of the population aged 0-49 years of Addis Ababa, using kebeles (urban dwelling associations) as clusters. METHODS: The sera used for this study were collected in an earlier study (1994) on the rate of acquisition of antibodies against measles, rubella, and hepatitis B. After separate approvals were obtained from the institutional ethics committees, sera were tested by enzyme-linked immunosorbent assay confirmed by Western blot. Age- and sex-specific HIV prevalence rates were estimated. The prevalence of HIV in men and women over 15 years of age was compared by calculating age-standardized HIV prevalence, using the age distribution of the census population as the standard. A time-dependent catalytic model was used to obtain crude estimates of HIV incidence from age-prevalence data. RESULTS: A total of 3853 sera were available for analysis. The prevalence of HIV in adults was 6.0% [95% confidence interval (CI), 4.5-7.4%] for men and 6.9% (95% CI, 5.3-8.5%) for women, with peak prevalence in the 25-29 year age group of 16.3 and 11.8%, respectively. After standardization for age using the direct method, the HIV prevalence ratio comparing adult men with women was 0.97:1 (95% CI, 0.70:1 - 1.35:1). Three children aged less than 5 years were HIV-positive. The prevalence of HIV among adults ranged from 0-21.3% in different clusters, indicating the heterogeneity of the spread of HIV in the city. HIV prevalence estimates among the antenatal clinic patients of Addis Ababa in 1996 far exceeded the estimates obtained during the community survey, particularly in the youngest age group (15-24 years). Estimates of HIV incidence (per susceptible person per annum) for the age group 16-22 years ranged from 1.3-2.25% for men and from 2.1-2.4% for women. CONCLUSION: By 1994, a substantial proportion of the adult population of Addis Ababa was infected with HIV. Promotion of behavioural changes and the control of sexually transmitted diseases should be strongly supported to limit the spread of the HIV epidemic in Ethiopia.

Plasmodium vivax and P. falciparum epidemiology in Gambella, south-west Ethiopia.

Plasmodium vivax and P. falciparum epidemiology were studied for parasitological and entomological samples collected during the period 1989 and 1990, respectively, from Gambella, South West Ethiopia. Of the total population examined (n = 1091), 147 (13.5%) were found to be positive for malaria parasites. Prevalence rates among males and females were 13.8% and 13.1%, respectively. Differences in the prevalence rates of malaria in the eleven villages were observed, the highest (33.3%) being in Ukuna 2 and the lowest (3.9%) in Ukuna 22. The dominant species of malaria found were both P. falciparum and P. vivax. 88.9% and 11.1% of the malaria cases of the general population were due to these parasites, respectively. It was also recognized that P. falciparum and P. vivax were prevalent in 81.6% and 18.4% of the Anuak population, respectively. The mosquito species responsible for malaria transmission were the indoor-resting A. gambiae s. l. and A. pharoensis. The parasite infection rates of these species were 0.76% and 0.46% and they were found to be the exclusive vectors of P. falciparum and P. vivax, respectively. The present findings are not in accord with the study results previously reported twenty years ago by Armstrong (1972) and Krafsur (1971). The most probable contributing factors for such switch of malaria transmission patterns were, the rehabilitation and resettlement programmes and agricultural activities undertaken in Gambella for the past 10 years that may have brought changes of the socio-economic situation and environmental factors.

Prevalence of hookworm infection and its association with low haematocrit among resettlers in Gambela, Ethiopia.

A cross-sectional survey of hookworm infection and haematocrit (HCT) levels was conducted in 7 resettled villages and 3 indigenous villages on sample populations selected by two-stage random sampling. Of 614 resettled persons and 187 indigenous persons, 65.5% and 60.4% respectively were infected with hookworm. Mean haematocrits for 664 resettled and 222 indigenous persons were 33.1% and 35.2%, respectively. A significant association (odds ratio = 2.65) was found between low haematocrit level (below the median for the sample population) and hookworm infection in the resettled population. Suggestions are made on the need for further studies and intervention programmes.