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Bioactivity of essential oils of local plants against adult Anopheles arabiensis (Diptera: Culicidae) in Ethiopia  [PDF]
Fekadu Massebo, Mekuria Tadesse, Meshesha Balkew, Teshome Gebre-Michael
Advances in Bioscience and Biotechnology (ABB) , 2013, DOI: 10.4236/abb.2013.48105
Abstract: The adulticidal activities of essential oils of eleven plants namely Chenopodium ambrosioides, Eucalyptus citriodora, Eucalyptus globules, Lippia adoensis, Mentha spicata, Nigella sativa, Ocimum lamiifolium, Ocimum suave, Piper nigrum, Schinus molle and Thymus vulgaris were assessed against a laboratory colony of Anopheles arabiensis in Ethiopia. The Centers for Disease Control and Prevention (CDC) glass bottle bioassay was adopted to conduct bioefficacy tests. For each replicate, ten blood-unfed female An. arabiensis were exposed to different concentrations of essential oils coated in glass bottles, and mortality was recorded at intervals of 5 minutes for one hour to assess the mean percentage mortality and LC50 and LC90 values. The residual toxicity of six essential oils was also assessed by exposing adult An. arabiensis in nylon netting Barraud cages treated by oils. Of all the essential oils assessed for adulticidal activities, O. suave was found to be toxic at low concentration (LC50 = of 0.0014 ml% v/v; LC90 = 0.0027 ml% v/v). The next efficacious oil was that of T. vulgaris with LC50 and LC90 values of 0.0028 ml% v/v and 0.005 ml% v/v, respectively. The lowest activity was due to S. molle, E. globulus and P. nigrum. At a concentration of 0.05 ml% v/v, O. suave killed 100% of An. arabiensis within five minutes of exposure, while P. nigrum at the same duration caused similar rate of mortality at a concentration of 50 fold. Residual toxicity tests revealed O. suave to persist for 15 days, killing all mosquitoes in the first five days and 80% up to 10 days. The lowest residual activity was noted for E. citriodora which
Utilization, retention and bio-efficacy studies of PermaNet? in selected villages in Buie and Fentalie districts of Ethiopia
Messay Fettene, Meshesha Balkew, Ciara Gimblet
Malaria Journal , 2009, DOI: 10.1186/1475-2875-8-114
Abstract: The objective of the study was to assess utilization and retention of PermaNet? nets distributed for malaria control in Buie and Fentalie districts and monitor the bio-efficacy of the nets using the WHO cone bioassay test procedures.A cross sectional study was carried out by interviewing household heads or their representative in Buie and Fentalie districts. The two districts were selected based on a priori knowledge of variations on ethnic background and housing construction. Clusters of houses were chosen within each of the study villages for selection of households. 20 households that had received one or more PermaNet? nets were chosen randomly from the clusters in each village. A total of eight used PermaNet? nets were collected for the bio-efficacy test. The bio-efficacy of PermaNet? nets was monitored according to the standard WHO procedures using a susceptible colony of Anopheles arabiensis to deltamethrin.A total of 119 household heads were interviewed during the study. The retention rate of nets that were distributed in 2005 and 2006 season was 72%. A total of 62.2% of the interviewees claimed children under five years of age slept under LLIN, while only 50.7% of the nets were observed to be hanged inside houses when used as a proxy indicator of usage of LLIN. For the bio-efficacy test the mean knock-down was 94% and 100%, while the mean mortality rate observed after 24 hr holding period was 72.2% and 67% for Buie and Fentalie districts respectively.The study revealed a moderately high retention of PermaNet? in the study villages and effectiveness of the nets when tested according to the standard WHO procedure.Malaria is a major public health problem in Ethiopia [1,2]. The country is most affected by malaria epidemics primarily due to its varying topographical and climatic features [3,4]. Malaria transmission in Ethiopia depends substantially on Anopheles arabiensis mosquitoes, a member of the Anopheles gambiae complex, in the intermediate highlands of Ethi
Environmental factors associated with larval habitats of anopheline mosquitoes (Diptera: Culicidae) in irrigation and major drainage areas in the middle course of the Rift Valley, central Ethiopia
Oljira Kenea, Meshesha Balkew & Teshome Gebre-Michael
Journal of Vector Borne Diseases , 2011,
Abstract: Background & objectives: Larval control is an integral part of malaria vector management in Ethiopia andelsewhere. For effective larval control, a sound understanding of the factors responsible for spatio-temporalvariation in larval production is essential. A study was thus conducted to characterize larval habitats of anophelinemosquitoes in irrigation and major drainage areas between Adami Tulu and Meki towns, in the middle course ofthe Ethiopian Rift Valley.Methods: Aquatic habitats were sampled for anopheline larvae and the associated environmental variables(water temperature, turbidity, water current, water pH and other variables) were measured, characterized andanalyzed.Results: Microscopic identification of the late instars (III and IV) of anopheline larvae collected throughout thestudy period yielded nearly 47.6% Anopheles pharoensis, 32.1% An. arabiensis, 17.1% An. squamosus and only3.2% of other species (An. coustani and An. cinereus). Larvae of the local malaria vectors, An. arabiensis andAn. pharoensis were most abundantly sampled from sand pools and natural swamps, respectively. Logisticregression analysis detected four best predictor variables associated with larval abundance of malaria vectorspecies. Thus, relative abundance of An. arabiensis larvae was significantly and inversely associated with aquaticvegetation and water current, whereas the relative abundance of An. pharoensis larvae was significantly andpositively associated with water temperature and the presence of algae in the water bodies.Conclusion: Dry season anopheline larval habitats such as riverine sand pools that are created and maintainedby perennial water bodies and their associated water development projects need to be considered in vectorcontrol operations.
Further studies on the phlebotomine sandflies of the kala-azar endemic lowlands of Humera-Metema (north-west Ethiopia) with observations on their natural blood meal sources
Teshome Gebre-Michael, Meshesha Balkew, Nega Berhe, Asrat Hailu, Yalemtsehay Mekonnen
Parasites & Vectors , 2010, DOI: 10.1186/1756-3305-3-6
Abstract: During the surveys (1996-2005), a total of 1963 sandflies of six Phlebotomus species (P. orientalis, P. papatasi, P. bergeroti, P. duboscqi, P. rodhaini and P. alexandri) were recorded from the study areas: the predominant species was P. orientalis in both localities. None of the total 618 P. orientalis females dissected (506 from Metema and 112 from Humera), nor the total 114 females of four other species dissected (P. papatasi, P. duboscqi, P. bergeroti and P. rodhaini) was infected with Leishmania promastigotes. ELISA-based blood meal analysis of 273 fresh fed P. orientalis females collected from Metema revealed a remarkably high bovine blood feeds (92%) with only 2.2% of human blood feeds.Based on abundance and other circumstantial evidences (its proven role in Sudan), P. orientalis is the most likely vector of VL in northwest Ethiopia, pending further clarifications. The zoophagic feeding behaviour of P. orientalis detected in the present study could have epidemiological significance, but more investigations are required in this and other behavioural characteristics towards appropriate management of the vector.Visceral leishmaniasis (VL) has been known in the Humera-Metema lowlands (northwest Ethiopia) since at least 1970 [1] and remains endemic in the region[2]. In this region, the disease is particularly associated with migration of non-immune labourers from the surrounding highland regions to the extensive agricultural development schemes in the lowlands [3,4]. Thus, at various times in the past, several outbreaks of the disease have occurred in the region. The most recent one that has started in 1995 appeared to be more serious claiming the lives of about 100-200 temporary farm labourers mainly from Maykadra village in Humera in just five months (August-December), in addition to 56 cases that were treated [2]. As far as is known, detailed epidemiological investigation in the region is lacking to reveal the exact distribution and magnitude of the recent outb
A zoonotic focus of cutaneous leishmaniasis in Addis Ababa, Ethiopia
Wossenseged Lemma, Girume Erenso, Endalamaw Gadisa, Meshesha Balkew, Teshome Gebre-Michael, Asrat Hailu
Parasites & Vectors , 2009, DOI: 10.1186/1756-3305-2-60
Abstract: Active case finding surveys were conducted in 3 localities, Saris, Kality, and Akaki, which are found in and around Bulbula-Akaki river gorges. During the surveys conducted in January 2005 - May 2006, a total of 35 cases with 9 active and 26 healed skin lesions were identified. Eighteen of the cases (51.4%) were found in Saris; while 10 (28.6%) and 7 (20%) cases were from Kality and Akaki respectively.Ten colonies of rock hyraxes (Heterohyrax brucei) were identified in the vicinities of the 3 localities. Three of the 48 hyraxes (6.3%) trapped from the surroundings harbored natural infections of Leishmania aethiopica. Confirmation of the Leishmania species of the 3 isolates was achieved by PCR amplification and RFLP analysis of the ribosomal DNA internal transcribed spacer (ITS) sequences. Based on sandfly species composition and proximity of resting sites to human settlements, Phlebotomus longipes is circumstantially proven to be the vector of CL in south east Addis Ababa.The study proves the existence of isolated zoonotic foci of CL in south eastern Addis Ababa, with P. longipes as the likely vector and H. brucei as the natural reservoir host.Ethiopian Cutaneous Leishmaniasis (ECL) is a widespread skin disease caused mainly by Leishmania aethiopica, but rarely by L. tropica and L. major; the latter two species cause ECL in the lowland regions [1-3]. The disease presents in three clinical forms: localized cutaneous leishmaniasis (LCL), mucocutaneous (MCL) and diffuse cutaneous leishmaniasis (DCL) [1-4]. LCL lesions are often benign and self healing; occasionally resulting in severe and persistent lesions. Persistent/severe LCL, MCL and DCL lesions are disfiguring [4-6], and often require protracted treatment schedules. In the case of DCL, definite cure is hardly ever achieved, since relapse is common. Precise figures on the numbers of ECL cases are lacking. Based on unofficial estimates, the total number of ECL cases diagnosed each year is around 20,000 [7].Two spec
Abundance and dynamics of anopheline larvae in a highland malarious area of south-central Ethiopia
Abebe Animut, Teshome Gebre-Michael, Meshesha Balkew, Bernt Lindtj?rn
Parasites & Vectors , 2012, DOI: 10.1186/1756-3305-5-117
Abstract: A study of the abundance and dynamics of Anopheles larvae was undertaken at different sites and altitudes in Butajira from July 2008 to June 2010. The sites included Hobe (1817?m.a.s.l), Dirama (1995m.a.s.l.) and Wurib (2196m.a.s.l.). Potential anopheline larval habitats were surveyed once per month in each village. The recorded characteristics of the habitats included habitat type, pH, surface debris, emergent plants, algae, substrate, turbidity, temperature, length, width, depth, distance to the nearest house and anophelines. The Spearman correlation coefficient and Mann–Whitney U test were used to calculate the degree of association between the density of anopheline species and key environmental factors.Among the different types of habitat surveyed, the Odamo, Akamuja and Assas streams and Beko swamp were positive for anopheline larvae. A total of 3,957 third and fourth instar larvae were collected from the three localities, and they represented ten species of anophelines. These were: Anopheles cinereus (32.5%), An. arabiensis (31.4%), An. chrysti (23%), An. demeilloni (12.2%), An. pretoriensis (0.6%), An. azaniae (0.1%), An. rufipes(0.1%), An. sergentii (0.06%), An. garnhami (0.06%) and An. pharoensis (0.03%). The density of anopheline larvae was highest during the dry months. An. arabiensis was widely distributed, and its density decreased from the lowest elevation in Hobe to the highest in Wurib. The density of An. arabiensis larvae was correlated positively with larval habitat temperature (r?=?0.33, p?<?0.05) and negatively with depth of larval habitat (r?=??0.56, p?<?0.05).Ten species of anophelines were identified, including two known vectors of malaria (An. arabiensis and An. pharoensis), along streams in Butajira. Larvae of An. arabiensis were found in streams at 2200m.a.s.l. This possible expansion of the malaria vector to highland areas indicates an increasing risk of malaria because a large proportion of the Ethiopian population live above this altitud
Insecticide resistance in Anopheles arabiensis (Diptera: Culicidae) from villages in central, northern and south west Ethiopia and detection of kdr mutation
Meshesha Balkew, Muntaser Ibrahim, Lizette L Koekemoer, Basil D Brooke, Howard Engers, Abraham Aseffa, Teshome Gebre-Michael, Ibrahim Elhassen
Parasites & Vectors , 2010, DOI: 10.1186/1756-3305-3-40
Abstract: Standard WHO insecticide susceptibility tests were conducted on adults reared from larval and pupal collections from breeding sites at three villages namely: Sodere in the Rift Valley, Gorgora in the north and Ghibe River Valley in the south west of Ethiopia. The occurrence of cross-resistance between pyrethroids and DDT was determined using a DDT selected laboratory colony originally collected from Gorgora. Phenotypically characterized mosquitoes were tested for the presence of knockdown resistance (kdr) alleles using the standard polymerase chain reaction assay.All An. gambiae s.l. specimens assayed by PCR were identified as An. arabiensis. The knockdown and mortality results showed An. arabiensis resistance to DDT in all villages, resistance to deltamethrin and permethrin in the Ghibe River Valley and permethrin resistance in Gorgora. Bioassay susceptibility tests also indicated the presence of cross-resistance between DDT and permethrin, but not between DDT and deltamethrin. The knockdown resistance (kdr) mutation of leucine to phenylalanine in the sodium ion channel gene was detected in populations from Gorgora and the Ghibe River Valley.Since An. arabiensis shows high levels of resistance to DDT in all villages tested and varying pyrethroid resistance in Gorgora and the Ghibe River valley, precautionary measures should be taken in future vector control operations. Moreover, the status of resistance in other locations in Ethiopia and the spread of resistant gene (s) should be investigated.Malaria vector control in Ethiopia is targeted mainly against Anopheles arabiensis as this species is responsible for transmitting Plasmodium falciparum and P. vivax [1]. Vector control measures including selective indoor residual spraying of dichlorodiphenyltrichloroethane (DDT), distribution of long lasting insecticide treated mosquito nets (LLINs) and source reduction of larval habitats are currently implemented by the Federal Ministry of Health in collaboration with intern
Assessment of level of knowledge and utilization of emergency contraception among female students of Hawassa University, south Ethiopia  [PDF]
Ejara Tolossa, Birhan Meshesha, Amanuel Alemu Abajobir
Advances in Reproductive Sciences (ARSci) , 2013, DOI: 10.4236/arsci.2013.13008
Abstract: Introduction: Emergency contraception is used as an emergency procedure to prevent unintended pregnancy secondary to an unprotected se xual intercourse and method failure. Hence, this study assessed the level of knowledge and utilization of emergency contraception among undergraduate regular female students of Hawassa University, south Ethiopia. Methods: An institution-based cross-sectional survey was conducted among female students of Hawassa University in December 2012. Seven hundred seventy six of the students were sampled by using multistage sampling technique. Pretested structured questionnaire was used to collect the data. Results: The majority 719 (92.7%) of female university students ever had sexual intercourse and 17 (2.2%) experienced forced sex. Eight (47%) of these 17 students experienced unintended pregnancy all of which resulted in an induced abortion. Three hundred seventy nine (72.2%) of the respondents had knowledge about emergency contraceptives and only 41 (10.8%) of them had ever used emergency contraceptives; oral contraceptive pills were the most widely used form of all emergency contraceptives 41 (10.8%). Age, marital status and age at menarche were associated with knowledge of emergency contraception; moreover, residence, year of study and experience of forced sex were found to be predictors of emergency contraception utilization. Conclusion: Female university students had been experiencing high rate of unintended sexual practice and pregnancy, low knowledge level and utilization of emergency contraceptives; moreover, they had no youth-friendly access to the services. Therefore, there is a need for collaborated effort to improve service access and scale up their utilization level to prevent unwanted pregnancy.
Assessment of the Effectiveness of Watershed Management Intervention in Chena Woreda, Kaffa Zone, Southwestern Ethiopia  [PDF]
Yericho Berhanu Meshesha, Belay Simane Birhanu
Journal of Water Resource and Protection (JWARP) , 2015, DOI: 10.4236/jwarp.2015.715102
Abstract: The main purpose of this study was to assess the effectiveness of watershed management intervention in Chena Woreda. A systematic sampling technique was used to select sample micro-watersheds, and random sampling method was used to select individual households from both intervention and non-intervention areas. Data were collected through field observation, household questionnaire survey, focused group discussion, in-depth interview and key informant interview. Moreover, physical soil and water conservation structures’ layout measurement was conducted. Descriptive statistics, t-test, chi-square test and participation index were used for data analyses. The study revealed that the intervention has good achievements in reducing soil erosion, improving water availability and quality, developing tree plantation and diversifying household income sources in the catchment. However, poor community participation, lack of the structures design alignment with standards, inappropriate time of implementation, lack of diversified soil water conservation measures, absence of regular maintenance and management of the structures were some of the major limitation of the intervention. Therefore, this study recommends that the stake-holders should make appropriate correction measures for observed failures and further interdisciplinary study should be conducted to explore the problems.
Parts of Speech Tagging for Afaan Oromo
Getachew Mamo Wegari,Million Meshesha
International Journal of Advanced Computer Sciences and Applications , 2011,
Abstract: The main aim of this study is to develop part-of-speech tagger for Afaan Oromo language. After reviewing literatures on Afaan Oromo grammars and identifying tagset and word categories, the study adopted Hidden Markov Model (HMM) approach and has implemented unigram and bigram models of Viterbi algorithm. Unigram model is used to understand word ambiguity in the language, while bigram model is used to undertake contextual analysis of words. For training and testing purpose 159 sentences (with a total of 1621 words) that are manually annotated sample corpus are used. The corpus is collected from different public Afaan Oromo newspapers and bulletins to make the sample corpus balanced. A database of lexical probabilities and transitional probabilities are developed from the annotated corpus. These two probabilities are from which the tagger learn and tag sequence of words in sentences. The performance of the prototype, Afaan Oromo tagger is tested using tenfold cross validation mechanism. The result shows that in both unigram and bigram models 87.58% and 91.97% accuracy is obtained, respectively.
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