Browsing by Author "Tesfaye Solomon"

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    Assessment of the Persistence of Malaria To Control Measures in Dembia District, Northwestern Ethiopia: A Retrospective and Longitudinal Prospective Study
    (Addis Ababa University, 2017-12-03) Tesfaye Solomon; Petros Beyene (Professor)
    Despite more than six decades of continued control effort, malaria remains a major public health problem in Dembia District. In order to determine the causes for the persistence of malaria to the control measures, retrospective and longitudinal prospective studies were conducted in the District. A retrospective data on monthly malaria incidence, malaria control interventions and meteorological variables were collected for the period 2001 to 2015. For the prospective parasitological surveys, all consenting family members selected randomly from four rural Kebeles were examined for the presence of malaria parasites following standard parasitological procedures. Knowledge, attitude and practice survey was conducted in parallel with parasitological surveys. Adult and larval mosquito surveys were undertaken in four selected Kebeles following standard entomological methods. Adult mosquitoes were collected indoors and outdoors and identified into species morphologically based on keys; their host preference and sporozoite infection rates were determined by enzyme linked immuno sorbent assay. The identification of Anopheles arabiensis was confirmed by polymerase chain reactions. In spite of increased indoor residual spraying coverge, retrospective data showed high malaria incidence in most years, except a sharp decline in 2006, 2007, 2008 and 2014. The incidence of monthly total malaria due to Plasmodium falciparum significantly (P<0.05) correlated with rainfall at one to four months lag. In the six month prospective parasitological surveys, a total of 4568 samples were examined microscopically. This showed an average of 7.4% positivity for malaria, of which 74.3% were due to P. falciparum and 20.4% P. vivax, whereas the remaining 4.4% and 0.9% were P. falciparum/P. vivax co-infections and P. ovale, respectively. Lack of consistency in indoor residual spraying practice in lower altitude Kebeles and not including malarious mid-altitude Kebeles in indoor residual spraying program explain the highest malaria incidence ii observed in the major malaria transmsion season (Sepember-December) in the reterospective and prospective studies. The prevalence of Plasmodium falciparum infections during the dry season appears to be the consequence of river edge pools created mainly by irrigation activities. The study also provided evidence that frequent population movements in and out of malarious areas in the region and outdoor human activities at night are common features that would impede the efficiency of malaria control measures. In addition, poor utilization of long lasting insecticidal net was determined as a factor contributing to the persistence of malaria in the region. The detection of one Plasmodium falciparum infected Anopheles arabiensis from outdoor collection in a sprayed (September) low altitude Kebele is an indication that outdoor transmsion may be taking place. This is another possible reason for the ineffective malaria control. One evidence for the wrong timing of indoor residual spraying operations for malaria control in the District was 50% P. falciparum sprozoite infected An. arabiensis collected during the wet season (June and August 2015). Therefore, the failure to target May to August malaria transmsion season by the malaria control activities as well as the disregard for malaria control in the mid-altitude localities appear to be the main weaknesses of the malaria control program in the District. In addition, increasing human outdoor activities which will expose them to the outdoor biting and resting behavior of Anopheles arabiensis, population movement and irrigation activities are important contributors for the persistence of malaria in Dembia District.
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    Prevalence of Malaria in the Highland Fringes of Butajira Area, Southern Ethiopia: a Retrospective and Cross- Sectional Study.
    (Addis Ababa University, 2008-07-05) Tesfaye Solomon; Petros Beyene (Professor)
    To determine the magnitude of malaria transmission in the highland fringes of Butajira area during the year 2006/07, a cross-sectional data on malaria prevalence was collected using standard parasitological, entomological and KAP study techniques. Retrospective data for the period between 2000/01 and 2005/06 was obtained by reviewing clinical records at Butajira Health Center. The retrospective clinical data showed malaria to be one of the major causes of outpatient consultations in the study area. The domiciles of the patients who received treatment for malaria at the District Health Center were Butajira town and the adjacent highland fringe rural localities. This indicated the transmission of malaria to be both in Butajira town and the adjacent highland fringe rural localities, all of which are higher than 2050m above sea level. In the parasitological survey conducted in October through December 2006, a 4.4% malaria positivity rate was detected. The majority (66.7%) of the infections were due to P. vivax and the rest were due to P. falciparum.The infections were observed in all age groups, with a relatively higher prevalence (3.6%) in adults. Difference in malaria prevalence was observed in the two localities of the study area with Misrak-Meskan, the lower highland fringe area, having a relatively higher peak season prevalence (5.3%) compared to that in Mirab-Meskan (2.7%). However, monthly incidence of malaria for October- November was not significantly different between the higher highland fringe areas (Mirab-Meskan) and the lower (Mirab-Meskan). Larval mosquito collections showed An. christyi was the dominant species during the major peak season (Oct-Dec) and during the small rainy season (Apr-May).However, An. gambiae s.l. was the dominant species in adult collections in both seasons suggesting that the adult mosquito sampling techniques used may have been more suited to its collection. More adult mosquitoes were collected outdoors than indoors in both localities, suggesting the likelihood of outdoor malaria transmission. The KAP survey showed that low proportion of household heads from Mirab-Meskan identified the role of mosquitoes in transmitting malaria as compared to those from Misrak-Meskan. This may be an indication that malaria transmission in Mirab-Meskan is a relatively new introduction, as a result of which the population has poor awareness about the disease. Therefore, health education about the risk of malaria in the upper highland fringes of Buitajira area must be given adequate attention to minimize potential epidemics. Furthermore, in light of its abundance, which coincided with the transmission seasons, the possible role of An. christyi as a secondary vector in the highlands must be investigated.