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

Management of Turcicum leaf blight [Exserohilum turcicum (Pass.) Leonard & Suggs] of maize (Zea mays L.) through integration of host resistance and fungicide at Bako, western Ethiopia

Open Access JournalTurcicum leaf blight (TLB) (Exserohilum turcicum) is a major disease affecting maize production in western Ethiopia. The objectives of this study were to determine the effect of maize varieties integrated with fungicides on epidemics of turcicum leaf blight; to determine the effect of turcicum leaf blight severity on yield and yield components of maize; and to assess the cost and benefit of using fungicides. The field experiment was conducted at Bako Agricultural Research Center in 2014 main cropping season using six maize varieties (BH-540, BH-543, BH-546, BH-660, BH-661 and AMHQ-760) integrated with foliar sprays of the systemic fungicide propiconazole (Tilt) at the rate of 350 ml ha-1 and the contact fungicide mancozeb (Dithane M-45) at 2.6 kg ha-1. The experiment was arranged in 3 × 6 factorial combinations in split plot design with three replications. A pinch of ground maize leaf infected by E. turcicum was inoculated at third-fifth leaves. Unsprayed plots were left as control or check for each variety. Disease severity was scored using 1 to 5 scale on 12 randomly-tagged plants in the central rows. Integration effects of varieties with fungicides significantly affected the grain yield and thousand kernel weight (TKW) of maize varieties. The highest (11383 kg ha-1) grain yield was obtained from propiconazole-treated hybrid maize variety BH-546. Turcicum leaf blight resulted in grain yield losses of up to 40.7% on the unsprayed plots of the susceptible variety BH-543. Percent severity index, AUDPC, incidence and disease progress rates were negatively correlated with yield components regardless of grain yield loss. The highest marginal benefit (ETB 48,801.28 ha-1) and marginal rate of return (ETB 6.33) were obtained from propiconazole-treated varieties BH-543 and BH-546, respectively. This study contributes to integrated TLB management options, and to make a valid recommendation for TLB management strategy, the study should be repeated over years and locations where TLB of maize is of major economic importance

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

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

Spin-dependent Seebeck coefficients of Ni_{80}Fe_{20} and Co in nanopillar spin valves

We have experimentally determined the spin-dependent Seebeck coefficient of permalloy (Ni_{80}Fe_{20}) and cobalt (Co) using nanopillar spin valve devices. The devices were specifically designed to completely separate heat related effects from charge related effects. A pure heat current through the nanopillar spin valve, a stack of two ferromagnetic layers (F) separated by a non-magnetic layer (N), leads to a thermovoltage proportional to the spin-dependent Seebeck coefficient S_{S}=S_{\uparrow}-S_{\downarrow} of the ferromagnet, where S_{\uparrow} and S_{\downarrow} are the Seebeck coefficient for spin-up and spin-down electrons. By using a three-dimensional finite-element model (3D-FEM) based on spin-dependent thermoelectric theory, whose input material parameters were measured in separate devices, we were able to accurately determine a spin-dependent Seebeck coefficient of -1.8 microvolt/Kelvin and -4.5 microvolt/Kelvin for cobalt and permalloy, respectively corresponding to a Seebeck coefficient polarization P_{S}=S_{S}/S_{F} of 0.08 and 0.25, where S_{F} is the Seebeck coefficient of the ferromagnet. The results are in agreement with earlier theoretical work in Co/Cu multilayers and spin-dependent Seebeck and spin-dependent Peltier measurements in Ni_{80}Fe_{20}/Cu spin valve structures

Determination of Local Barley (Hordeum Vulgare) Crop Coefficient and Comparative Assessment of Water Productivity for Crops Grown Under the Present Pond Water in Tigray, Northern Ethiopia

An experiment was carried out in 2010 at Mekelle, in northern Ethiopia, to measure the evapotranspiration, to estimate barley crop coefficient (kc), and to evaluate the water productivity taking into account the major crops grown under the present pond irrigation system. Four locally made lysimters were installed in the middle of barley field to measure barley evapotranspiration. The single crop coefficient approach was used to estimate barley crop coefficient. The average seasonal evapotranspiration of barley was 375 mm which is similar to many other cereal crops in the region. The single crop coefficient values for early, vegetative, mid and late crop stages were 0.6 – 0.8, 0.6 – 1.0; 1.0 – 1.05 and 0.3 - 0.4 respectively. The result showed that these crop coefficient values obtained in this experiment were similar to the crop coefficient values obtained in the past except for kc initial. Therefore, the assumption that local barley crop coefficient values differ from that of the documented values was incorrect. Furthermore, the major reason for mismanagement of irrigation water in barley fields was not due to use of wrong crop coefficient values but could be due to inadequate irrigation technical skill and knowledge of the farmer. The average economic water productivity (EWP) of barley for the very wet, wet, normal, dry and very dry seasons scenario were 0.99, 0.7, 0.65, 0.57, and 0.44 USD m-3, respectively, whereas the corresponding crop water productivity (CWP) values for grain were 1.53, 1.08, 1.0, 0.88 and 0.68 kg m-3, respectively. The EWP and CWP of barley were compared with onion and tomato under pond water irrigation at the five climatic scenarios. The crop water productivity for tomato and onion were 85 – 87% and 76 – 78% higher than that of barley, respectively. The corresponding economic water productivity for tomato and onion were 87 – 89% and 81 – 82% higher than that of barley, respectively. We concluded that growing tomato and onion would bring more income or yield per m3 of pond water supplied than growing barley. The implication is that as supply and demand determines the price of products, farmers and extension workers need to balance the crop area coverage per irrigation scheme so that undesirable price falls and rises could be avoided. Evaluation of crops based on their water productivity would improve the productivity of irrigation schemes and ultimately improve food security in the arid and semi-arid areas where water scarcity is critical problem and irrigation is a necessity for crop production. Key Words: Barley, Evapotranspiration, Crop coefficient, Water productivity

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

Management of undescended testes: a retrospective study from a tertiary hospital in Ethiopia

Background: Undescended testis is one of the commonest congenital malformations seen in boys. The aim of this study is to evaluate the pattern of presentation, approach to diagnosis, treatment and follow up in Tikur Anbesa Specialized Hospital, a tertiary teaching hospital in Ethiopia.Methods: This is a retrospective cross sectional study of all boys with undescended testis operated in Tikur Anbesa Specialized Hospital between September 2012 and August 2014.Results: Of 82 boys operated within the study period, 66 boys with 78 undescended testes are studied. Twenty-six percent (17/66)came before the age of 2 years, while the majority of the study group, 50% (33/66), presented beyond 5 years of age. Of the 17 boys brought to the hospital before 2 years, only 41% (7/17) them were treated before the age of two years. The majority 89% (59/66) of the boys were treated after 2 years of age. Seventy-one testes of 78 [91%] were in the inguinal canal, 5 were intra-abdominal and 2 were absent. 46% (36/78) were on the left side, 29% (23/78) on the right side and the rest were bilateral. Among the 54 boys who had ultrasound examination, the ultrasound report is consistent with operative findings in 33 [61%]. Associated congenital malformations were found in 31.8% (21/66) of the boys. Hypospadia was the predominant malformation comprising 38% (8/21) of the total congenital malformations. Orchidopexy was done for 82% (64/78) of the total testes, orchiectomy was done for 9% (7/78) and biopsy was taken in 1 case. Among the total operated boys only 62% (41/66) were followed in our clinic; of those who had follow up 10% (4/41) testes atrophied and 1 [2%] testis retracted.Conclusion: Boys with undescended testes present and are treated late in Tikur Anbesa Hospital. As opposed to the literatures most of the undescended testes were found on the left side. Ultrasound examination cannot be the only mode of examination for undescended testes as it misses more than one third of the cases. Hypospadia is the commonest associated congenital malformation. Post operative follow up is very poor after treatment for undescended teste