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Cismaan shiine rift valley fever thesis

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MAPPING OF RIFT VALLEY FEVER IN SOMALILAND THESIS

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Cismaan shiine rift valley fever thesis

  1. 1. SEHISheikh Technical Veterinary School (STVS)Mapping of Rift valley feverrisk areas in SomalilandA mini thesis submitted in a partial fulfilment forrequirements for the award of Diploma in LivestockHealth Sciences (DLH) of sheikh technical veterinaryschool. BY: Osman Abdulahi Farah Roll number: STVS/0087 Supervisor Dr. Ismail Kane July 2011 1
  2. 2. DECLARATIONI, Osman Abdulahi Farah declare that the work presented here is my original work, and has not appeared anywhere else in any other form except for the references made from other published works.Students Name : ………………………………………………………………..Signature: …………………………………………………………….................Supervisor signature: ………………………………………………… 2
  3. 3. ACKNOWLEDGEMENTIn the name of Allah, the Most Gracious and the Most Merciful Alhamdulillah, all praises toAllah for the strengths and His blessing in completing this thesis. Special appreciation goes tomy supervisor, Dr Ismail Kane, for his supervision and constant support. His invaluable helpof constructive comments and suggestions throughout the thesis works have contributed tothe success of this research. Not forgotten, my appreciation to my Tutor of informationtechnology Mr. Mohamed Aden Ahmed and Abdirahman Bare Dubad for their support andknowledge regarding this topic. I would like to express my appreciation to the Dean of studies in (STVS) Dr Abdulahi Sheikh Mohamed Nour, H.O.D in STVS officer, Dr Ibrahim Osman Suleiman, principal of STVS Dr. Thomas Bazarusanga, all my Tutors in STVS for their support during my education in veterinary and STVS administration for their encouragements. Sincere thanks to all my fellow students in STVS like Hassan Adam Hussein for his technical support and my unforgettable class mates for their kindness and moral support during my study.Last but not least, my deepest gratitude goes to my beloved parents; Mr. Abdullah Farah Xamse and Mrs. Zahra Mohamud Hussein and also to my sisters and brothers for their endless love, prayers and encouragement.CONTENTS PAGE NO 3
  4. 4. Cover page…………………………………………………………………………………...1Declaration------------------------------------------------------------------------------------------------2Acknowledgement----------------------------------------------------------------------------------------3Table of Contents-----------------------------------------------------------------------------------------4CHAMPTER ONE INTRODUCTION AND LITERATURE REVIEW................................61.1 General Introduction ………………………………………………..………………….....61.2 Literature review of RFV disease……………………………………………………….....81.2.1 Disease definition…………………………………………………………………......91.2.2 A aetiology of the Rift Valley fever………………………………………………......91.2.3 Epidemiology of the Rift Valley Fever…………………………………….. ……......91.2.4 Pathogenesis………………………………………………………………………......91.2.5 Implication of human healthy………………………………………………………....91.2.6 Geographic distribution of Rift valley Fever………………………………………...101.2.7 Environmental conditions…………………………………………………………....111.2.8 Modes of transmission…………………………………………………………….....121.2.9 Clinical signs of Rift Valley fever…………………………………………………....131.2.9.1 Sheep and Cattle…………..…………………………………………………….…....141.2.9.2 Goat…………………………………………………………………….....................141.2.9.3 Human………………………………………………………………………...……...141.2.9.4 Camel………………………………………………………………………………...151.2.10 Pathology of RVF………………………………………………………………….....161.2.11 Diagnosis and Vaccination………………………………………………………...…171.2.12 Control………………………………………………………………….…………....181.2.13 Mapping of RFV disease……………………………………………………….........191.3. General and specific objectives……………………………………………………..…..191.3.1 General objectives……………………………………………………………………...191.3.2 Specific Objectives…………………………………………………………...…...........19CHAPTER TWO METHOD AND MATERIAL....................................................................202.1 Data collection....................................................................................................................202.2 Data Management and Analysis.........................................................................................202.3 Administrative structure of Somaliland.............................................................................202.4 laboratory techniques.........................................................................................................222.5 Description of study of study area……………………………………………………….22 4
  5. 5. 3.5.1 Climate geography……………………………………………………………………..23CHAPTER THREE RESULTS.............................................................................................. 24CHAPTER FOUR DISCUSSION...........................................................................................254.1discussion……………………………………………………………………………........25CHAPTER FIVE CONCLUSION AND RECOMMEDATION............................................285.1 Conclusion………………………………………………………………………………..285.2 Recommendation…………………………………………………………………………28ANNEX ONE REFERENCE ……………………………………………….…………........29CHAPTER ONE: GENERAL INTRODUCTION AND LITERATURE REVIEW1.1 introduction 5
  6. 6. Rift Valley fever (RVF) is one of the most serious trans-boundary animal diseases. It is amosquito-borne viral disease, which causes periodic severe epidemics, principally involvingruminant animals. RVF is also an important zoonosis and one of the significant acutehaemorrhagic fevers affecting human beings and animals (Shoemaker 2002).The disease is most severe in sheep, cattle, goat, producing high mortality in newbornanimals and abortion in pregnant animals, it is a zoonosis and human become infected fromcontact with tissue of infected animals or mosquito bite.(Shoemaker 2002).RVF activity reported in 25 African countries (Meganand Bailey, 1989; Peters and Lin-thicum, 1994).The disease results in high mortality and abor-tions in domestic animals, and amortality rate of less than 1 percent among humans (Peters and Linthicum, 1994).Rift Valley Fever was first recorded in South Africa in 1950-51 in the Northern Cape,Western Free State and the then Southern Transvaal. It started in the Western Free State inDecember 1950 and it continued until April 1951.The first documented epizootic of RVF occurred on a farm in 1930-1931 near LakeNaivasha, Kenya with high mortality among sheep (Daubney et al., 1931).The name RiftValley refers to the location of the first isolation of the virus in the Rift Valley region ofKenya dominated by Savanna grasslands. Their findings showed that the disease was vectorborne, transmitted by a variety of mosquito species, and affected both domestic animals andhumans.During 1977 ,epidemic occurred along the Nile delta and Valley in Egypt, causing anunprecedented number of human infections and deaths, as well as numerous abortion in sheepand goat and some loses in goats, and camels,In September 2000, RVF broke out simultaneously in Jizan province in South West Arabianad joint Yemen (Shoemaker 2002)A recent outbreak in Saudi Arabia and Yemen, (September through November 2000)documents for the first time the occurrence of the RVF virus outside of continental Africa(WHO, 2000). And as the main exporting country of livestock from Somalia, the firstsuspected of this disease was Somalia as result of outbreak in yemen and Suadi Arabiaanimals exported to Somalia was boycotted resulting overstocking and depreciation ofanimal price contribute to household economy decrease. 6
  7. 7. And the diseases come in to being in Somalia as a result of the events which coincided withEl-Niño in 1997 –1998 in the region. Targeted surveillance in sero-positive sites in centraland south Somalia was carried out by the Somali component of the PACE project in 2004.Following the massive RVF epizootic in north-eastern Kenya in 2006 – 2007, around a 100human cases were suspected and one confirmed in southern Somalia (WHO/CDC), in parallelwith reports of high abortion rates in the small ruminants. As from January 2007, a targetedsurvey was initiated in the Afmadow District (South) SAHSP (Somali Animal Health ServiceProject 2007) .The outbreaks were confined to north-eastern Kenya and the southern regions of Somalia andno cases were reported in northern Somalia (FAO, 1998; WHO, 1998). However, consideringthe frequent movement of livestock from south and central Somalia to the north (and fromPuntland to Somaliland) for export, the risk is considerable enough for importing countries tosuspect the presence of RVF in Somaliland and Puntland where animals are shipped and forauthorities of these States to carry out surveillance activities.However, the application of statistically valid methods in Somalia is difficult due to thepastoral nomadic context. The high mobility of livestock and the lack of a suitable samplingframe for the lower administrative divisions make it nearly impossible to apply rigorousrandom sampling methods.Screening in Somaliland in 2001 and in Puntland in 2003 which targeted mainly sheep andgoats aged 1–2 years (97% of surveyed animals) revealed no signs compatible with thedisease but an overall sero-prevalence of 2 _ 0.02% (90/4570) and 5 _ 0.3% (206/4050),respectively, Although results of the screening in Somaliland 2001 showed infectionprevalence in most region (five to six) the number of positives herds were concentrated inSanaag, Togdheer, and Sool region located within the Nugal Valley with a herd of prevalenceof 21 to 22 and (30%), this compared to 9 and 12% in Hargeisa and Sahil Regions.this survey (GIS) software (Arcview1) was used to generate at random the required numberof sites within the area where sampling needs to take place, be it at zone, country, region oreven district level.As result of limited studies of rift valley fever in Somaliland this study wasaimed to show risk areas in Somaliland by using Arc GIS software version 9.3.1.LITERATURE REVIEW1.2.1 Definition of the disease 7
  8. 8. Rift Valley fever (RVF) is acute or per acute disease of domestic ruminants in Africa andMadagascar, caused by a mosquito- borne virus and characterized by fever, abortion, necrotichepatitis and haemorrhages, high mortality in young animals but infection are frequently inapparent or mild,1.2.2 Aetiology of RVFRVFV has morphological and physiological properties typically of a member of thephlebovirus of the Family Bunyaviriadae (Woods 2002).A host cell derived bi-lipid- layer enveloped through which virus coded glycoproteincomposed of the three RNA segments, L(large),M(medium ),S(small )it contained in aseparate nucleocapsid within the viron , R FV is an enveloped virus with a diameter of 80 to120 mm.RVFV, which attaches to receptors on susceptible cells, it internalised by endocytosis andreplication occur in the cytoplasm by budding through endoplasmic reticulum in the Golgiregion (Struthers, & swanepoel 1982).The virus can be grown in and readily produce cytopathic effect and plaque in virtually allcommon continuous line and primary, including Primary calf and lamb kidney or tests cells,the only exception s being primary macrophages and lymphoblastoid cell lines (Peter, 1981).1.2.3 Epidemiology of the RVFRVF is widespread in African and serious outbreaks have been encountered in both animalsand man in Egypt, Sudan, Kenya, South Africa, Zimbabwe, Zambia, and Senegal (Peters,1981).Over the last 40 years, numerous RVF outbreaks have occurred in most countries of sub-Saharan Africa as well as Madagascar and Egypt (Meegan 1981, Zeller et al. 1997, House etal. 1992).Many of these outbreaks have been devastating to farming economies due to the associatedlivestock losses and prohibited trade. In September 2000, RVF cases were confirmed in SaudiArabia and Yemen, marking the first reported occurrence of the disease outside the Africancontinent. 8
  9. 9. This outbreak raised concerns that RVF virus may continue to spread to areas with a varietyof ecological conditions that were previously uninfected with the virus (Jupp et al. 2002,Anyamba et al. 2006, Bird et al. 2007, Evans et al. 2007, WHO 2007b).1.2.4 Pathogenesis of the RVFAfter injection of the virus in tissue, initial replication occur at the site of infection followedby viraemia and localisation of the virus in the target organs especially the liver, spleen andkidneys. Further, replication of the virus in these organs amplifies the viraemia, severedestruction of the hepatic cells, which is caused by the cytopathic effects for the virus (Peter,1981).Damage to the blood vessel walls causes vasculitis and widespread haemorrhages in theaffected tissue (Maar & Genfand 1979).1.2.5 Implication of human healthyhuman become infected from contact with infected tissue or from mosquito bite , in contrastto the main vectors in the Egypt epidemic of 1977- 78 in south Africa people become infectedin contract with animals tissue , for instance where no such history can be obtained an it mustassumed that infection has resulted from mosquito bite.(Chambers, and warepoel. 1980)Generally, person s who become affected are involve in livestock industry such farmers, whoassist in dystocia of livestock , farm labourers, who salvage carcasses for human consumption,veterinarian and their assistants, and abattoir workers .( Maar & Genfand 1979)Many reports of human becoming infected with RVF while, investigating the disease in thefield or laboratory. (Findlay, 1932)Moreover, highest infection rates were found in workers in the by-product section of abattoirin Zimbabwe Human infection results from infected virus with abraded skin, wound or mucusmembrane in the field during Egypt epidemic. (Brown 1981)The first known human fatalitywas recorded in 1943 in laboratory worker in the USA soon after the initial isolation of thevirus (Schweitzer and Rivers, 1934), since the infection was complicated by thrombophlebitisand patient died from pulmonary embolism.1.2.6 Geographic Distributions 9
  10. 10. Since the first major outbreak of RVF was recorded close to Lake Naivasha in Kenya in1930-1931 (Daubney et al. 1931, CDC 2004b), RVF outbreaks in Africa have occurred as farnorth as Egypt, throughout most of sub-Saharan Africa and as far south as Southern Africa(House et al. 1992, Davies and Martin 2003). One of the most notable epizootics of RVFoccurred in Kenya in 1950-1951 and resulted in the death of an estimated 100,000 sheep(CDC 2004b). The 1977 RVF outbreak in Egypt resulted in both animal and human casesand it was believed to have started due to the importation of RVF virus infected domesticanimals from Sudan (Gad et al. 1986, Peters and Linthicum 1994). In 1987 transmission ofthe RVF virus to humans in West Africa (Senegal, Mauritania) was linked to the alteredinteractions between humans and mosquitoes that resulted from flooding of the lower SenegalRiver during construction of the Senegal River dam project (CDC 2004b).In 1997- 1998 a RVF outbreak in East Africa affected 89,000 people and caused over 400deaths (Gerdes 2004). A severe form of the disease was seen in Mauritania (1998) wheremany thousands of people became sick, 200 people died, and abortion losses in livestockwere heavy (CDC 2004b, Gerdes 2004).The 2000 outbreak in Saudi Arabia and Yemen was particularly alarming as this was the firsttime RVF virus was detected outside the African and created mosquito-breeding habitats. Injust four months, 155 people had died, and the outbreak had forced the closure of livestockmarkets in Kenya devastating the economy of the region (CDC 2007).From November 2006 through March 2007 RVF outbreaks occurred in Somalia, Tanzania,Sudan, and Kenya (ProMed Mail 2007). In Kenya alone, there were 684 human cases with155 deaths (Linthicum et al. 2008).The most recent cases of clinical disease or infection (without clinical disease) involvingdomestic ruminant livestock and humans have occurred in Madagascar, South Africa, andSudan (WHO 2008, OIE 2008, Kasari et al. 2001.2.7 Environmental Conditions 10
  11. 11. The role of environmental elements in the epidemiology of vector-borne diseases such asRVF is well known. Environmental elements such as climate (e.g., temperature, humidity,annual rainfall, intensity of rainfall), hydrology (e.g., proximity to lake/dam, irrigation,accumulated water, proximity to river), and topography (e.g., elevation, land- cover)influence vectorial capacity (House et al. 1992, Chevalier et al. 2004a, Turell et al. 2005,Clements et al. 2006). To have high vectorial capacity, which in turn increases theprobability of contact between hosts and vectors and the likeliness of RVF virusestablishment and spread, competent vectors must be in an environment suitable for vectorbioecology (e.g., population dynamics and biting activity ) and virus transmission (Turell etal. 2005).Environmental conditions can affect the ability of mosquitoes to transmit arboviruses such asRVF virus. For instance, the extrinsic incubation (EI) period (the time interval betweeningestion of the virus and subsequent transmission by the mosquito) of RVF virus depends onambient temperature (Brubaker and Turell 1998, Turell et al. 1985, Turell 1989, House et al.1992, Diallo et al. 2005). In general, studies have consistently shown that the EI period isinversely related to temperature (Turell et al. 1985). However, the magnitude of the effect oftemperature on both infection and transmission rates appears to vary for different virus-mosquito combinations (Turell et al. 1s985).Changes in climate (e.g., humidity, rainfall, and temperature) can alter the geographic rangesand life cycles of plants, animals, insects, bacteria, and viruses (Longstreth and Wiseman1989).Climate changes conducive to vector bioecology in habitats frequented by host species couldresult in vector population growth and increased disease transmission (Longstreth andWiseman 1989).1.2.8 Modes of Transmission 11
  12. 12. The mode of RVF virus transmission may be vector-borne, airborne or from direct contactwith body fluids of infected animals. May transmit the RVF virus mechanically (Hoch et al.1985, House et al. 1992, Davies and Martin 2003), mosquitoes are the main RVF vectorstransmitting the virus to animals and humans (Meegan and Bailey 1988).Many mosquitoes (e.g., Aedes, Anopheles, Culex, Eretmapodites, and Mansonia), transmitthe RVF virus and are infected naturally (Turell and Bailey 1987, Turell et al. 1990, Traore-Lamizana et al. 2001, Chevalier et al. 2004a).RVF virus is most often transmitted to humans by Aedes and Culex species of mosquitoes(Linthicum et al. 1999, CDC 2004b). Transmission of RVF virus to people working with livestock (e.g., when slaughtering orhandling infected animals or touching contaminated meat during the preparation of food or inlaboratory facilities) has frequently been an indicator of epizootic RVF virus activity (Daviesand Martin 2003). Infection through aerosol transmission of RVF virus has resulted fromcontact with laboratory specimens containing the virus (Davies and Martin 2003, CDC2004b), however, there have been no recorded direct human-to-human transmission of RVFvirus to date (Kasari et al. 2008).RVF virus is maintained in the eggs of female floodwater Aedes mosquitoes, which breed inisolated grassland depressions called dambos (Linthicum et al. 1985). The eggs are capableof surviving in dry soil until the next heavy rainfall floods the dambos producing favourableconditions for the eggs to hatch. Subsequently, very large numbers of adult mosquitoesemerge (Linthicum et al. 1984; Davies et al. 1985, Ba et al. 2005, Anyamba et al. 2006) and,if infected, transfer the RVF virus to livestock and other animals on which they feed. Thesevertebrate blood meal hosts may become infected and develop a viremia (Linthicum et al.1985, Evans et al. 2007). RVF epizootic periods result when waters persist a month or morepast the emergence of Aedes mosquitoes.Secondary vector species (e.g., Culex spp.) to breed, generate large populations, feed onanimals with high levels of viremia (Linthicum et al. 1985, Davis and Martin 2003, Chevalieret al. 2004a, Evans et al. 2007), and subsequently spread infection to animals beyond the areaof the original outbreaks (Linthicum et al. 1999, Anyamba et al. 2001, Woods 2002, CDC2004b). Cattle and sheep are the primary amplifiers of the disease (Meegan and Bailey 1988,Longstreth and Wiseman 1989, Kasari et al. 2008). It has also been suggested that reservoiranimals (RVF infected rodents or wild ruminants) may be affecting domestic animals in 12
  13. 13. shared grasslands, and thus, maintain the virus during inter-epizootic periods. Sylvatic(wildlife-mosquito) cycling of RVF virus could maintain the virus at low levels and enabletransmission of the virus from wildlife to wildlife and occasionally to livestock (Evans et al.2007). Although Evans et al. 2007 found that African wild ruminants do become infectedwith RVF virus,Figure1, Rift valley fever virus transmission cycle (from Davies and Martin 2003).1.2.9 Clinical sign of RVFRVF virus is a zoonotic pathogen endemic to Africa (Peters and Linthicum 1994).The susceptibility to and severity of RVF virus infection in numerous vertebrates (e.g., cattle,sheep, goats, camels, rodents, wild ruminants, buffaloes, and antelopes, ) has beendetermined during epizootics and in laboratory studies. Although RVF virus infects a widerange of hosts, including humans, the most significant infections occur in domestic livestock(e.g., sheep, cattle, goats, camels, and buffalo)1.2.9.1 Sheep and CattleThe most important animal species in RVF epidemics are sheep and cattle. Both sheep andcattle suffer significant mortality (e.g., greater than 90% in lambs and calves less than one 13
  14. 14. week of age) and abortion (virtually 100%) after infection, and they become sufficientlyviremic to infect many arthropod vector species (Peters and Linthicum 1994, House et al.1992, EFSA 2005).Sheep are extremely susceptible to RVF virus.Onset is marked by high fever (40-42oC). Significant clinical features in affected lambs, kids,and adult sheep also include listlessness, weakness, anorexia, rapid respiration, excessivesalivation, vomiting, fetid diarrhoea, and abortion (Daubney et al. 1931, House et al. 1992).In older lambs and adults, the incubation period is between 24 and 72 hours, and the mortalityrate is 20-30% (House et al. 1992). The most severe reactions occur in newborn lambs andkids, which die within hours of infection, rarely surviving more than 36 hours (Linthicum etal. 2008).Cattle Adult cattle exhibit clinical signs of disease infrequently, but some may develop acutedisease with clinical features similar to those of sheep. Frequently abortion is the onlymanifestation in this species. The mortality rate in native adult non-pregnant cattle does notusually exceed 10 percent (House et al. 1992). are less severely affected with RVF thansheep.The mortality rates in calves are generally lower than in lambs and vary widely (20-70%)between outbreaks (Peters and Linthicum 1994, House et al. 1992, OIE 2008).1.2.9.2 Goats Goats are generally less severely affected than sheep (e.g., 1977-78 Egyptian outbreaks),with much lower morbidity and mortality, fewer abortions, and less severe clinical signs(Imam et al. 1979, Davies and Martin 2003). Abortion in goats and mortality in kids wererecorded in Kenya in 1930, the Sudan in 1973, South Africa and Namibia in 1974-75, and inWest Africa in 1987 (EFSA 2005). Older kids and goats may develop in apparent, per acuteor acute disease (OIE 2008).1.2.9.3 CamelsCamels do not normally show any clinical signs of RVF infection, however, antibodies toRVFV have been detected in camels and RVF virus has been isolated from then during 14
  15. 15. epidemics, As in cattle and sheep, high abortion rate (100%) is a common consequence of theinfection in pregnant animals and neonatal mortality may occur in camel foals born duringRVF epizootic periods (Davies and Martin 2003)in Senegal and South Africa (Gora et al. 2000, Chevalier et al. 2004a). Nevertheless, severalstudies have suggested that rodents play no role in natural outbreaks of RVF in Africa(Davies 1975, Swanepoel et al. 1978, EFSA 2005). In addition, Poultry and wild birds are not susceptible to RVF virus (Davies and Martin2003).1.2.9.4 HumansHumans with RVF typically have either no symptoms or mild Influenza-like illness withfever, generalized weakness, muscle and joint pain, dizziness, photophobia, anorexia, andsometimes nausea and vomiting (Davis and Martin 2003, CDC 2004b). Recovery usuallyoccurs within 4-7 days, however, in some cases the disease progresses to ocular disease.Other, often fatal, complications include hemorrhagic fever and encephalitis (which can leadto headaches, coma, or seizures). In humans the case mortality rate is generally low(approximately 1%), but full recovery may be protracted and long-term ocular andneurological complications have been reported (FAO 2008). However, in some casesmortality can be as high as approximately 25% when proper public health interventions arenot undertaken during an epidemic/epizootic as was the case in Sudan in 2007 (WHO 2007b).1.2.10 Pathology of Rift Valley FeverThe hepatic lesions of RVF are essentially similar in all domestic animals and humans,varying with the age of the affected individual. (Coetzer. 1977) In most severe lesions occur 15
  16. 16. in aborted sheep foetuses and new born- lambs in which the liver is usually moderately togreatly enlarged , soft, friable and yellowish-born to dark reddish –brown in colour withirregular congested patches and some lines haemorrhages of varying size scatteredthroughout the parenchyma (Easterday,B.C.,1963)Hepatic lesions in new- born lambs are almost invariably accompanied by numerouspetechiae and ecchymoses in the mucosa of the abomasums and its content are dark chocolate–brown as result of the presence of partially digested blood.Most mature sheep and cattle the spleen is slightly to moderately enlarged, withhaemorrhages in the capsule. Sometimes in Adult sheep edges of the spleen becomes dark-blue-ish –red, circumscribed areas, 10 to 20 mm in diameter. (Coetzer, J.A.W and Mesi, G.d.1975)Lesions in newborn lambs are pyknosis and karyorrhexis of lypmnodes in lymphoid tissue,cloudy swelling and hypotropic degeneration of the epithelial cells of the convoluted tubulesof the kidney and necrosis of the some cellular element in the glomeruli in ten per cent oflambs, multifocal necrosis and haemorrhages in the adrenal cortex (Coetzer 1977).Many animals have lung congestion, alveolar and interstitial oedema, haemorrhages, a fewfibrin thrombi in alveolar walls, emphysema, scattered neurophils infiltration and necrosis ofinterlobular septa and peri-bronchial lymphoid tissue. (In human encephalitis is characterizedby focal necrosis with leukocyte infiltration and perivascular cuffing)(Van ders.1985).1.2.11 Diagnosis and VaccinationThe mild influenza-like symptoms in single human cases of RVF can be confused with manyviral diseases. However, a RVF epizootic outbreak should be suspected if there is a suddenand widespread onset of many abortions in domestic animals, high neonatal mortality and 16
  17. 17. acute febrile disease with the presence of liver lesions. Cases of disease in people associatedwith the affected animals also assist in making a tentative RVF diagnosis. Climatic andecological factors such as the presence of high mosquito populations and/or flooding ofgrassland depressions can contribute to provisional RVF diagnoses (Davies and Martin2003).There are two types of laboratory tests used to confirm provisional RVF diagnoses. The firstis to identify or isolate the RVF virus or antigen. For example, the virus can be isolated viaintraperitoneal inoculated mice or hamsters, immunofluorescent or peroxidase staining oftissue culture, simple agar gel immune diffusion tests using liver or spleen tissue, andimmune sera RT-PCR (reverse transcription-polymerase chain reaction) (Davies and Martin2003, OIE 2008).The second method to confirm provisional RVF diagnoses is to detect specific antibody to theRVF virus. The presence of RVF specific antibody or IgM can be demonstrated withenzyme-linked-immunosorbent serologic assay (ELISA), microtiter virus-serumneutralization tests in tissue culture, or plaque reduction tests in tissue culture (Davies andMartin 2003, OIE 2008).No specific treatment exists for Rift Valley fever, In most humans RVF cases, symptoms aremild and are managed with supportive therapy. Both inactivated and live-attenuated vaccineshave been developed to help control RVF outbreaks (House et al. 1992). Routine vaccinationof non-pregnant livestock in Africa is recommended prior to outbreaks, but has beenprohibitively expensive, leading to endemicity of RVF in most African countries (Balkhy etal. 2003, Davies and Martin 2003, OIE 2008). No vaccine is currently licensed orcommercially available for humans or livestock in the United States (WHO 2007b, Britch etal. 2007).1.2.12 ControlControl of vectors and host movements is necessary to interrupt the epidemiological cycle ofRVF virus and thereby lessen the potential impact of an outbreak by lowering diseasetransmission rates. Effective vector control methods include hormonal inhibitors such asmethoprene, widespread use of vehicle or aerial mounted insecticide sprays targeting adult 17
  18. 18. mosquito species, and strategic treatment of mosquito breeding habitats and soils withlarvicides and insecticides, respectively (Davies and Martin 2003).Since viremic host animals could arrive in an uninfected country within the incubationperiod, movement of animals for trade from enzootic/epizootic areas should be banned duringRVF epizootic periods (Davies and Martin 2003). Also important in controlling diseasespread to and among humans is public education to discourage practices that promotetransmission. This includes educating the public to avoid direct contact with the blood andbody fluids of sick or dead animals unless appropriate levels of personal protection are usedand to use personal protection against mosquito bites (e.g., long-sleeved shirts and pants andmosquito repellent).1.2.13 Mapping of the RVFA GIS is a computer-based system that combines digital geo-referenced (spatially- related)and descriptive data for mapping and analysis (Brooker et al. 2002, Connor et al. 1995). Oneof the main strengths of a GIS is its ability to integrate different types of spatial and non-spatial data (Brooker et al. 2002).some examples of the types of data overlaid and analyzedusing GIS are population data (e.g., census, socio-economic, and animal population data), 18
  19. 19. land-use and public infrastructure data, transportation networks data (e.g., roads andrailways), health infrastructure and epidemiological data (e.g., data on mortality, morbidity,disease distribution and healthcare facilities), and environmental and ecological data(e.g.,climate and vegetation data) (Kamel et al. 2001).GIS technology can be used to manage and monitor different aspects of disease, fromincident tracking to epidemiologic analysis and assessment of risks (Allen and Wong 2006).For example, a GIS can be used to map available epidemiological information and relate it tofactors known to influence the distribution of infectious diseases, such as climate and otherenvironmental factors that affect vector bioecology (Brooker et al. 2002, Allen and Wong2006).1.3 GENERALAND SPECIFIC OBJECTIVES1.3.1 GENERAL OBJECTIVESThe general objectives of this mini thesis are to show areas of risk of rift valley fever inSomaliland regions.1.3.2 SPECIFIC OBJECTIVESTo indicate high-risk areas in Somaliland regions by using ArcGIS softwareTo estimate prevalence of surveyed four regions in Somaliland.CHAPTER TWO MATERIALS AND METHODS2.1 Data CollectionThe input of data was obtained from SAHSP office in Hargeisa, where relevant informationwas expected to be available like Ministry of livestock. In addition, data were selected insurvey of four regions in Somaliland where ArcGIS software /Stata IC 11.0 was used. 19
  20. 20. 2.2 Data Management and AnalysisData from SAHSP were managed and entered into databases by using ArcGIS version 9.13(Brooker) 2002, (Connor et al. 1995) due to short time of study. For the statistical analysisthe software Stata IC/11 was used to carry out exploratory analysis of potential RVF Alsowere used data input of excel Microsoft programme.2.3 Administrative structure of SomalilandThe Somaliland administrative structure has frequently been subject to Modification, to thisserological study of mapping RVF there are 4 regions composed of (12) districts. Each regioncomposed 30 locations and out of this four regions were selected where 900 samples wereextracted and the animals bleed were Sheep and Goat in those four regions. But Age groupwere different according sheep and goat.Table 1: Structure of the different administrative levels of samplingIncluded in the Regionabove District Location SitesadministrativelevelTotal 4 12 30 900Mode - 164 30 313Average 225 75 30 331Range 198 134 5 38Table 2: List of relevant variables included in the database along with the number ofobservations available Variable Number of samples % of samples for for which it was which it was recorded recorded 20
  21. 21. Localization Region 900 100% District 900 100% Location 900 100% Site 900 100% Species Goat 456 51% Sheep 444 49% Age 1-5 Sex Male 356 40% Female 544 60%Map2. Shows sampling location 21
  22. 22. 2.4 Laboratory techniquesField collection samples during the survey of serological investigation samples were sent toNairobi laboratory were used IgG antibodies of ELISA to confirm the presence of RVF Virussurveyed regions in Somaliland.2.5 Description of the Study areaThe republic of Somaliland is located in the Horn of Africa. Its boundaries are defined by theGulf of Aden to the north, Somalia in the east, Ethiopia in the South West, and in thenorthwest. It lies between the 08°00 – 11°30 parallel north of the equator and between42°30 – 49°00 meridian east of Greenwich. The capital of Republic of Somaliland is the cityof Hargeisa (elevation 1347 meters) but the country has a total area of 137,600 km 2 withcoastline that extends about 850km along the southern African shores of the Gulf of Adenhowever, The population of the Somaliland is about 3.5 million,The country is divided into six regions namely; Maroodi jex, Awdal, Sahil, Togdheer, Sooland Sanaag that are sub divided into 33 districts. 22
  23. 23. Figure2 shows map of study area2.5.1 Climate and GeographySomaliland is situating between 8o and 12o north of the equator. Climatically the country hassemi arid warm weather, where the daily average temperature ranges from 25o to 35Co.The country’s three distinguish topographical features are the GUBAN, or the hot arid coastalplains; the rolling highland of the Oogo which also contains some rugged and inaccessiblemountain ranges and Hawd plateau which stretches well into Ethiopian territory Southwards.The coastal plain Oogo is very hot, with maximum temperature balanced around 30 oCthroughout the year, reaching 40oC-45oC between May and September. Rainfall is generallyscarce, and vegetation is sparse. Somaliland is characterized by its great variations intopography, climate and population. The four distinct seasons are: two main rainy seasonsknown as “GU “or spring from April to June and short season “Deyr”or autumn rainy periodfrom September to November and two dry seasons of” Hagaa” or summer form July toAugust and then long dry, cold “Jilaal”or winter from December to March. 23
  24. 24. CHAPTER THREE RESULTTable 1: Prevalence of Rift Valley in the four surveyed regions Number of samples Prevalence with 95% collected in each region and Confidence Intervals % of the whole survey RegionsMarodi jex 60 (7%) 0.15 (0.05-0.25)Sanaag 318 (35%) 0.116352201 (0.11-0.15)Sool 270 (30%) 0.185185 (0.18-0.25)Togdheer 252 (28%) 0.107142827 (0.10-0.14)Total 900 (100%) 0.137 (0.13-0.15)Map1 of Rift Valley Survey ResultMap2 shows Rift Valley Risk sites serological status 24
  25. 25. Map3 shows Somaliland Digital Elevation Model (DEM)Map 4 shows Somaliland Rift Valley Risk Areas 25
  26. 26. CHAPER FOUR DISCUSSION4.1 DiscussionAs one way of extracting information, desk review has been used due to the short time frameof the study period. Therefore, an already stored data has been received from SAHSPregional office through Dr. Ismail Kane with permission from Ministry of livestock. And thedata was analyzed in ArcGIS view programme to identify the high risk areas for rift valleyfever in Somaliland regions.As recommended by James (1998) and applied by Terra Nuova in a previous surveys inSomaliland and Puntland, and to overcome the lack of sampling frame due to high mobilityof animals which encompasses as one of the pastoral nature of the communities surveyed,GIS system has been sorted out as the only method to help us achieve our objective to Iidentify the high risk areas in Somaliland.Over all sero-prevalence of this study was (14%) which is high according to previous reportsin Somaliland (Berkvens 2001) and in punt-land 2003 has prevalence of (5%) because in2001 rainfall was not so much compared to 2002 – 2004 that is why carrier vectors highlyspread of RVF virus in those animals which are susceptible to the disease.However, the comparison made between four surveyed regions risk areas of rift valley feverin Somaliland are Sool and Marodi jex as show on Map 5 compared to Sanaag and Togdheerand this is in agreement with previous studies conducted by Terra Nuova with help ofMinistry of livestock. (Berkvnes 2001).In general as table1 in results shows comparison made on prevalence of RVF in foursurveyed regions in Somaliland with their interval confidence respectively 95%, Sool has19%, (0.18-0.25) Marodi jex15% (0.05-0.25) Sanaag 12% (0.11-0.15),Togdheer0.11.%(0.10-0.14),As result of prevalence Sool and Marodi jex has the highest prevalence of the disease and thismight be the movement of animals in Sool to Nugal valley which provide a favourablecondition to vectors for the growth of the vector prevails and provide a favourable condition,exposing the area to reveal high case of positive RVF rising to the top of risk areas identifiedin the study. Thus, the root cause of detecting the disease in such arid areas can be the changeof movement pattern of animals observed in the areas. 26
  27. 27. Admittedly, the landscape of these region with positive case can be allowing the disease toget established as in shown in Map 3 in the result this study and these regions borders likeEthiopia and surrounding districts have a large water catchment surface and at the same timeborders.Sool located to Nugal which have a very large valley that often harbours the most favourablecondition for the survival and proliferation of Aedes spp (low elevation ground, hightemperature, superficial and underground rivers which supply sporadic natural poolssurrounded by dense vegetations) it found Grazing areas and watering points and the Soolpastoral community moves towards the valley in search of water and pasture and thismovement is facilitated by the blood relation to the inhabitants in the valley while Marodi jexpastoral communities moves towards Ethiopia also Marodi jex risk factor are plat andwatering point that is why become high at risk of disease also those districts have watercatchments and watering points that cause vector to be abundant.Usually, the disease is basically dependent on the weather pattern in the study area as it isvector. And in general Somaliland is termed to be laid in the Arid of east Africa giving thatRVF is very hard to get established in the area as endemic disease. After, 2000 embargo bythe Arab governments there launched a joint rift valley survey by Terra Nuova and Ministryof livestock revealing that there was a recent out breaks or high viral circulation in Sanaagand Sool which the recent outbreak idea was refuted as it did not happen before the studyhowever, the expectation of RVF outbreak was high.As shows table 2 that sheep 49% are the least reared species when compared to goats 51%while the herd is dominated by the female (60%) of herds and this is because, apart frombreeding, males (40%) are sold as source of cash for the household to cater other domesticneeds like sugar, drugs, food and clothes.CHAPTER FOUR CONCLUSIONS AND RECOMMENDATION5.1 ConclusionThis study was aimed at producing by mapping RVF of risk areas in Somaliland regions, sothat it can help to improve the management and control of RVF vector in those regions,although the environment drivers that determine the life cycle of the vector with high riskslike Sool and Maroodi jex compared to Sanaag and Togdheer, the most importance to 27
  28. 28. identify and visualize areas of high rift valley fever in Somaliland is to put place areas whichare likely to become infected through sero- monitoring of those areas.The sampling method using a GIS facilitated significantly the implementation of the RFVinvestigation in Somaliland. in particular, high-risk areas of four regions in Somaliland. Theycan be monitored and analysed newly available technologies of ArcGIS soft ware.Similarly, a survey was carried out in Somaliland of screening sampling by using ArcGISsoftware in 2001.This mini thesis is important to create operational maps that could help the vector control andpriority areas of risk for disease control in future.Hence, the maps were constructed to allow targeting with regions of high risk areas of RVF,accordingly.5.1 RecommendationBased on finding of this study of mapping risk areas four of Somaliland regions, followingrecommendations were given as follows  Ministry of livestock and relevant veterinary NGO’s should develop the capacity to identify ecological factors of mosquitoes to insure risk areas or create buffer zone.  To make public awareness about controlling the vector and to avoid the spread of disease in those regions.  Those regions were at risk for the establishment of RVF and should provide insecticide in human also Spraying could help the people to recover because the disease can be transmitting through contact of tissue of the infected animals and through mosquito bite from affected person to another person.  Community to use proper dispose of trash or anything that hold water.ANNEX ONEREFERENCE 28
  29. 29. Barnard B.J.H. (1979). – Rift Valley fever vaccine – antibody and immune response in cattle to a liveand an inactivated vaccine. J. S. Afr. vet. med. Assoc., (vol, 3), page 155-157.Brooker S, 2002, Use of remote sensing and a geographical information system in a nationalhelminthiasis control programme in Chad. Bull World Health Org.; 80(10):783-9.Coetzer J.A.W. (1977). – The pathology of Rift Valley fever. I. Lesions occurring in natural cases innewborn lambs. Onderstepoort J. vet. Res., page 44, 205-212.Daubney R, Hudson JR, Graham PC. (1931), Epizootic hepatitis or Rift Valley fever: an undescribedvirus disease of sheep, cattle and man from East Africa. Journal of Pathology and Bacteriology.34:545-79.Eisa, M., Kheir el-Sid, E. D., Shomeir, A. M., and Meegan, J. M. (1980): "An outbreak of Rift Valleyfever in the Sudan--1976 [letter]." Transactions of the Royal Society of Tropical Medicine andHygiene, page 74(3), 417-9G.M.Findlay (1931) Trans, Roy. Soc. Tropical. Medical Hygienic page 25: 229-262.Linthicum KJ, Bailey CL, Davies FG, Tucker CJ.(1987). Detection of Rift Valley fever viral activityin Kenya by satellite remote sensing imagery. Science, page: 1656-9.Linthicum KJ, Bailey CL, Tucker CJ, Mitchell KD, Logan TM, Davies FG, Kamau CW, Thande PC,Wagateh JNA 91990)- O a application of polar-orbiting, meteorological satellite data to detectflooding of Rift Valley Fever virus vector mosquito habitats in Kenya. Med Vet Entomol.;4(4):433-8.Meegan JM, Bailey CH. Rift Valley fever, 1988: Monath TP, editor. The Arboviruses: Epidemiologyand Ecology, vol. 4. , pp. 51–76.Peters CJ and Linthicum KJ (1994), Rift Valley Fever. In: Beran GW, Steeke JH, editors. Handbookof Zoonoses: Section B. Viral. 2nd ed., illustrated. Boca Raton, FL: CRC Press; page 125. 29

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