Sheikh Technical Veterinary School (STVS) Mapping of Rift valley fever risk areas in Somaliland A mini thesis submitted in a partial fulfilment for requirements for the award of Diploma in Livestock Health Sciences (DLH) of sheikh technical veterinary school. BY: Osman Abdulahi Farah 1
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SEHI
Sheikh Technical Veterinary School (STVS)
Mapping of Rift valley fever risk areas in Somaliland
A mini thesis submitted in a partial fulfilment for requirements for the award of Diploma in Livestock Health Sciences (DLH) of sheikh technical veterinary school.
BY: Osman Abdulahi Farah
Roll number: STVS/0087
Supervisor Dr. Ismail Kane
July 2011
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DECLARATION
I, 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
Table of Contents-----------------------------------------------------------------------------------------4
CHAMPTER ONE INTRODUCTION AND LITERATURE REVIEW................................6
1.1 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……………………………………………………..…..19
1.3.1 General objectives……………………………………………………………………...19
1.3.2 Specific Objectives…………………………………………………………...…...........19
CHAPTER TWO METHOD AND MATERIAL....................................................................20
2.1 Data collection....................................................................................................................20
2.2 Data Management and Analysis.........................................................................................20
2.3 Administrative structure of Somaliland.............................................................................20
neutralization tests in tissue culture, or plaque reduction tests in tissue culture (Davies and
Martin 2003, OIE 2008).
No specific treatment exists for Rift Valley fever, In most humans RVF cases, symptoms are
mild and are managed with supportive therapy. Both inactivated and live-attenuated vaccines
have been developed to help control RVF outbreaks (House et al. 1992). Routine vaccination
of non-pregnant livestock in Africa is recommended prior to outbreaks, but has been
prohibitively expensive, leading to endemicity of RVF in most African countries (Balkhy et
al. 2003, Davies and Martin 2003, OIE 2008). No vaccine is currently licensed or
commercially available for humans or livestock in the United States (WHO 2007b, Britch et
al. 2007).
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1.2.12 Control
Control of vectors and host movements is necessary to interrupt the epidemiological cycle of
RVF virus and thereby lessen the potential impact of an outbreak by lowering disease
transmission rates. Effective vector control methods include hormonal inhibitors such as
methoprene, widespread use of vehicle or aerial mounted insecticide sprays targeting adult
mosquito species, and strategic treatment of mosquito breeding habitats and soils with
larvicides and insecticides, respectively (Davies and Martin 2003).
Since viremic host animals could arrive in an uninfected country within the incubation
period, movement of animals for trade from enzootic/epizootic areas should be banned during
RVF epizootic periods (Davies and Martin 2003). Also important in controlling disease
spread to and among humans is public education to discourage practices that promote
transmission. This includes educating the public to avoid direct contact with the blood and
body fluids of sick or dead animals unless appropriate levels of personal protection are used
and to use personal protection against mosquito bites (e.g., long-sleeved shirts and pants and
mosquito repellent).
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1.2.13 Mapping of the RVF
A 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). One
of 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 analyzed
using GIS are population data (e.g., census, socio-economic, and animal population data),
land-use and public infrastructure data, transportation networks data (e.g., roads and
railways), 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, from
incident 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 to
factors known to influence the distribution of infectious diseases, such as climate and other
environmental factors that affect vector bioecology (Brooker et al. 2002, Allen and Wong
2006).
1.3 GENERALAND SPECIFIC OBJECTIVES
1.3.1 GENERAL OBJECTIVES
The general objectives of this mini thesis are to show areas of risk of rift valley fever in
Somaliland regions.
1.3.2 SPECIFIC OBJECTIVES
To indicate high-risk areas in Somaliland regions by using ArcGIS software
To estimate prevalence of surveyed four regions in Somaliland.
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CHAPTER TWO MATERIALS AND METHODS
2.1 Data Collection
The input of data was obtained from SAHSP office in Hargeisa, where relevant information
was expected to be available like Ministry of livestock. In addition, data were selected in
survey of four regions in Somaliland where ArcGIS software /Stata IC 11.0 was used.
2.2 Data Management and Analysis
Data 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 analysis
the software Stata IC/11 was used to carry out exploratory analysis of potential RVF Also
were used data input of excel Microsoft programme.
2.3 Administrative structure of Somaliland
The Somaliland administrative structure has frequently been subject to Modification, to this serological study of mapping RVF there are 4 regions composed of (12) districts. Each region composed 30 locations and out of this four regions were selected where 900 samples were extracted and the animals bleed were Sheep and Goat in those four regions. But Age group were different according sheep and goat.
Table 1: Structure of the different administrative levels of sampling
Included in the above administrative level
RegionDistrict Location Sites
Total 4 12 30 900
Mode - 164 30 313
Average 225 75 30 331
Range 198 134 5 38
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Table 2: List of relevant variables included in the database along with the number of observations available
Variable Number of samples for which it was recorded
% of samples for which it was recorded
Localization
Region900 100%
District900 100%
Location900 100%
Site900 100%
Species
Goat456 51%
Sheep444 49%
Age1-5
Sex
Male356 40%
Female544 60%
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Map2. Shows sampling location
2.4 Laboratory techniques
Field collection samples during the survey of serological investigation samples were sent to
Nairobi laboratory were used IgG antibodies of ELISA to confirm the presence of RVF Virus
surveyed regions in Somaliland.
2.5 Description of the Study area
The republic of Somaliland is located in the Horn of Africa. Its boundaries are defined by the
Gulf of Aden to the north, Somalia in the east, Ethiopia in the South West, and in the
northwest. It lies between the 08°00' – 11°30' parallel north of the equator and between
42°30' – 49°00' meridian east of Greenwich. The capital of Republic of Somaliland is the city
of Hargeisa (elevation 1347 meters) but the country has a total area of 137,600 km2 with
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coastline that extends about 850km along the southern African shores of the Gulf of Aden
however, The population of the Somaliland is about 3.5 million,
The country is divided into six regions namely; Maroodi jex, Awdal, Sahil, Togdheer, Sool
and Sanaag that are sub divided into 33 districts.
Figure2 shows map of study area
2.5.1 Climate and Geography
Somaliland is situating between 8o and 12o north of the equator. Climatically the country has
semi 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 coastal
plains; the rolling highland of the Oogo which also contains some rugged and inaccessible
mountain ranges and Hawd plateau which stretches well into Ethiopian territory Southwards.
The coastal plain Oogo is very hot, with maximum temperature balanced around 30 oC
throughout the year, reaching 40oC-45oC between May and September. Rainfall is generally
scarce, and vegetation is sparse. Somaliland is characterized by its great variations in
topography, climate and population. The four distinct seasons are: two main rainy seasons 23
known as “GU “or spring from April to June and short season “Deyr”or autumn rainy period
from September to November and two dry seasons of” Hagaa” or summer form July to
August and then long dry, cold “Jilaal”or winter from December to March.
CHAPTER THREE RESULT
Table 1: Prevalence of Rift Valley in the four surveyed regions
Regions
Number of samples collected in each region and % of the wholesurvey
Prevalence with 95% Confidence Intervals
Marodi 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 Result
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Map2 shows Rift Valley Risk sites serological status
Map3 shows Somaliland Digital Elevation Model (DEM)
Map 4 shows Somaliland Rift Valley Risk Areas
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CHAPER FOUR DISCUSSION
4.1 Discussion
As one way of extracting information, desk review has been used due to the short time frame
of the study period. Therefore, an already stored data has been received from SAHSP
regional office through Dr. Ismail Kane with permission from Ministry of livestock. And the
data was analyzed in ArcGIS view programme to identify the high risk areas for rift valley
fever in Somaliland regions.
As recommended by James (1998) and applied by Terra Nuova in a previous surveys in
Somaliland and Puntland, and to overcome the lack of sampling frame due to high mobility
of 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 I
identify the high risk areas in Somaliland.
Over all sero-prevalence of this study was (14%) which is high according to previous reports
in Somaliland (Berkvens 2001) and in punt-land 2003 has prevalence of (5%) because in
2001 rainfall was not so much compared to 2002 – 2004 that is why carrier vectors highly
spread 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 fever
in Somaliland are Sool and Marodi jex as show on Map 5 compared to Sanaag and Togdheer
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and this is in agreement with previous studies conducted by Terra Nuova with help of
Ministry of livestock. (Berkvnes 2001).
In general as table1 in results shows comparison made on prevalence of RVF in four
surveyed regions in Somaliland with their interval confidence respectively 95%, Sool has