ticks were sampled in the villages of diiso and el - humow and at the livestock market and abattoirs in garissa district , north eastern province of kenya , during april  may 2008 ( figure ) .
garissa district is in a semi - arid to arid ecologic zone that receives sporadic rainfall from march to may ; vegetation consists primarily of acacia - commiphora bushes .
its population is largely composed of nomadic herders who travel between districts in northern kenya in search of water and pasture ( 8) . location of garissa district ( a , box ) in north eastern province , kenya , and tick collection sites ( b ) .
ticks were picked by hand from infested livestock , stored in labeled sterile vials , and transported in liquid nitrogen to the kenya medical research institute laboratory . in the laboratory , ticks were washed in sterile water , rinsed first with 70% ethanol , and then rinsed with minimum essential medium containing antimicrobial agents ( 100 u / ml penicillin , 100 g / ml streptomycin , and 1 l / ml amphotericin b ) .
they were identified to species by using taxonomic keys ( 9,10 ) and pooled in groups of 2 to 10 by species , sex , collection date and site , and host .
the tick pools were homogenized by using 90-mesh alundum sand in a prechilled , sterile mortar and pestle with 1.6 ml2 ml ice - cold bovine albumin 1 medium ( 1 medium 199 with earle salts , 1% bovine albumin , 100 u / ml penicillin , 100 g / ml streptomycin , and 1 l / ml amphotericin b ) under high containment .
the homogenates were clarified by centrifugation at 1,500 rpm for 15 min at 4c , and supernatants were stored at 80c .
viral rna was extracted from tick homogenates by using trizol - ls ( invitrogen , carlsbad , ca , usa ) reagent , according to the manufacturer s instructions .
rna was screened by reverse transcription pcr ( 11 ) to amplify a 536-bp fragment of the gene encoding for the nucleocapsid protein in the small ( s ) segment of the cchfv genome by using the following primers ( 12 ) : cchf f2 ( 5-tggacaccttcacaaactc-3 ) and r3 ( 5-gacaaattccctgcacca-3 ) , positions 135153 and 653- 670 , respectively , on the reference strain cchfv 10200 .
electrophoresis of the pcr products was performed by using 1% agarose gels in tris - acetate - edta buffer containing ethidium bromide ; product bands were visualized and documented with the canon uvp photodoc - it gel imaging system ( uvp , llc , upland , ca , usa ) mounted with a digital camera .
the pcr products of a subset of 4 of the cchfv - positive homogenates were purified by using the qiaquick pcr purification kit ( qiagen sciences , germantown , md , usa ) , according to the manufacturer s instructions , and sequenced by using the bigdye terminator version 3.1 cycle sequencing kit ( applied biosystems , foster city , ca , usa ) and the abi 3730 and automated 3130xl genetic analyzer ( applied biosystems ) . the sequences were analyzed by using the basic local alignment search tool ( blast ; http://blast.ncbi.nlm.nih.gov/blast.cgi ) and the genbank database to confirm the identity of the virus .
data ( including tick species , collection site , animal host , and virologic test results ) were entered into an excel database ( microsoft corp . ,
redmond , wa , usa ) and analyzed by using pivot tables . a total of 8,600 ticks , of 3 genera and 8 species , were sampled primarily from camels , cattle , goats , and sheep , principally hyalomma rufipes and hy .
ticks of the genus hyalomma were sampled 3 more frequently in diiso than in el - humow ( table ) .
rufipes ( 3 from cattle and 1 from a camel ) , 18 pools of hy .
truncatum ( 14 from cattle and 4 from camels ) , and 1 unidentified hyalomma species ( table ) in which single dna bands corresponding to the predicted 536-bp pcr product were detected . * cchfv , congo - crimean hemorrhagic fever virus .
the detection of cchfv in pools of hyalomma spp . ticks from diiso village and the garissa district slaughterhouse provides strong evidence of cchfv presence in northeastern kenya and indicates that cchfv circulation in kenya is underestimated .
livestock play a role in the amplification of the virus because the animals become viremic for 7 days ( 2,3 ) , during which time they can infect more ticks .
our findings indicate that cchfv circulates in northeastern kenya with substantial involvement of camels and cattle .
the detection of cchfv in ticks from camels at the slaughterhouse also suggests the potential of exposure for abattoir workers .
the presence of cchfv among hyalommid ticks in northern kenya highlights the risk to the resident population and requires the assessment of human exposure .
health care workers must therefore help create awareness among the population and take steps to prepare for and prevent outbreaks .
 as part of ongoing arbovirus surveillance , we screened ticks obtained from livestock in northeastern kenya in 2008 to assess the risk for human exposure to tick - borne viruses . 
 of 1,144 pools of 8,600 hyalomma spp . 
 ticks screened for congo - crimean hemorrhagic fever virus by reverse transcription pcr , 23 pools were infected , demonstrating a potential for human exposure . 
The Study
Conclusions