Tsavo Mobile Veterinary Unit - November 2008

The activities for the month of November are described below

The activities for the month of November are described below.

Rinderpest Disease Surveillance:


For three weeks between October 27th and November 18th, we undertook the surveillance of rinderpest disease in the Tsavo ecosystem. A total of 108 animals comprising of 90 (83.3%) buffaloes (Syncerus caffer), 5 (4.6%) giraffes (Giraffa camelorpadalis), 11 (10.2%) waterbucks (Kobus ellipsiprimnus) and 2 (1.9%) lesser kudus (Tragelaphus imberbis) were sampled.  The sero-surveillance was concentrated in areas where the Somali livestock either directly or indirectly interact with the local livestock and wildlife. These included areas around Voi, Irima and Ndii, Ndara plains and Maungu, Ngutuni sanctuary near Voi, Bachuma, Sala and Kulalu, Maktau and Ziwani in Tsavo West, Taita ranch and Taita Hills wildlife sanctuary (Salt Lick) as well as Luarenyi ranch. Most of the livestock is from the Somali ecosystem brought to the ranches for trade and fattening.

We targeted animals born after the last sero-surveillance in April 2006. The ages of buffaloes ranged between 10 months and 10 years (average 2.28 years) with 93.3% aged between 1 and 4 years. Only six buffaloes were above 5 years.  Waterbucks were aged between 2 and 3 years and giraffes between 1½ to 2 years. One giraffe was estimated at 6 years. The lesser kudus were estimated at 3½ and 4 years. Animals were assessed to be healthy with no evidence of rinderpest disease or signs of any other infectious condition.

The samples were submitted to the Director of Veterinary Services in the Ministry of Livestock for onward transmission to the national investigation laboratory at Kabete, the regional rinderpest reference laboratory at Muguga and the international rinderpest reference laboratory at Pirbright UK. The surveillance work was funded by Pan African Campaign on Enzootics (PACE-SERECU) under the auspices of the African Union- Inter African Bureau for Animal Research (AU-IBAR).


The main objective of the sero-surveillance exercise was to prove the absence of circulation of rinderpest virus in the Tsavo ecosystem by sampling susceptible species in critical livestock-wildlife interfaces.

Specific objectives were to examine, sample and establish the status of key buffalo herds in the Tsavo East National Park especially the buffalo herds sampled and proved to be negative in 2006. We also aimed at sampling animals in the southern part of Tsavo West National Park as well as ranches nearby to establish their status after the last negative results in 2006. There is considerable direct and indirect interaction of wildlife and the Somali livestock in the area.

Significance of the Tsavo ecosystem in Rinderpest Disease Surveillance:

The ecosystem is considered critical in rinderpest surveillance because of marked interaction of wildlife and livestock which increases the potential for disease transmission. The ranches neighbouring the parks comprise an important dispersal area for wildlife from the protected areas especially in the dry seasons. Currently, majority of the ranches have been leased to the Somali pastoralists. The number of livestock is beyond the carrying capacities of the ranches leading to serious grazing encroachment into the parks. Because the Somali ecosystem is still suspected to be infected with rinderpest, it then follows that sero-surveillance of the disease should extend to the Tsavos because of direct and indirect interaction of local livestock and wildlife with livestock from this ecosystem.

Areas Sampled:

As mentioned earlier, we targeted areas of high wildlife-livestock interactions. We aimed to sample buffalo herds that were sampled in 2006. Herds sampled that time and were also sampled during the current exercise were the Irima herd that in 2006 was sampled near Kanderi. We also sampled two herds at Ngutuni sanctuary that we believe were sampled near Aruba in 2006. Two other herds were sampled at Ndara plains close to where two herds were sampled in 2006. No buffalo herd was found near Bachuma in 2006 and other species were sampled instead. This year however, we found a large herd of about 1,500 buffaloes from which 14 animals were sampled. We also sampled four giraffes near Bachuma gate. Also sampled in 2006 and during this exercise was a herd of habituated buffaloes at Taita ranch. Six waterbucks and two lesser kudus were also sampled around Voi (airstrip and Voi safari lodge) and Ndii respectively.

Livestock encroachment into the park in Sala area has displaced most of the wildlife into the interior of the park. We did not locate any buffalo herds in areas sampled in 2006 but we believe two herds sampled at Sobo about 30Km from Sala gate and between Sobo and Sala gate could be the same herds we sampled during the last sampling. Three buffalo herds were sampled near Kulalu hills at the border of the park and Kulalu ranch. Galana River was too full during the sampling period and hampered sampling in the northern sector of Tsavo East at the boundary with Galana ranch where sampling was done in 2006. Also sampled near Sala gate were five waterbucks.

In Tsavo West we sampled a buffalo herd and a giraffe near Murka and another herd near Maktau. There were no herds located in Ziwani and Jipe areas where sampling was done in 2006. Four herds were sampled in Taita Salt Lick sanctuary and Luarenyi ranch. These herds were not sampled in 2006. 

Surveillance Method:

Buffalo herds would first be located by a fixed wing aircraft and the GPS coordinates taken for each location. The team would then move in and dart from the vehicle. Before darting would commence, estimation of the herd size would be done and the herd observed for any signs of disease, the general health status and any abnormalities in composition, etc. Animals of suitable ages would be darted in quick succession with the Dan-Inject® darting rifle. After induction, sampling would commence. Each animal would be clinically examined, blood samples taken, age and sex the animals before reviving them with the appropriate antidotes. Aging was done using the eruption pattern of the incisor teeth and horn development. Ages selected were >1 year and < 6 years to avoid complications of maternal immunity or previous exposure. Most animals sampled were born after the last sampling in 2006. The other species were also located and darted from the ground.  The immobilisation drugs used for all animals were Etorphine and Xylazine Hcl at the appropriate recommended doses for each species. They were revived with Diprenorphine and Atipamezole Hcl respectively.

Samples collected included whole blood from which sera was extracted by centrifugation after >6 hours of clotting. It was placed in 2ml Cryovials in six aliquots and labeled appropriately, then frozen immediately in liquid nitrogen. They were transported in this state and submitted to the Director of Veterinary Services (DVS) at Kabete for eventual transmission to the national, regional and international rinderpest diagnosis labs at Kabete, Muguga and Pirbright in UK respectively.

Observations and conclusions of the survey:

Observation of the buffalo herds and other wildlife species ascertained that the animals were healthy and did not reveal any disease symptoms. The animals immobilised in both parks and examined clinically were in good body condition with no clinical signs indicative of any infectious disease.

Other Activities in November

November was rather quiet with only one incident of animal injury at Dida Harea in Tsavo east. This has been the trend in previous years when such incidents reduce following the rains. The said animal was an elephant aged about 15 years with a long standing injury from a deeply embedded snare on the mid left fore leg. Tissues had covered the snare all round apart from posterior part of the leg at the snare knot where there was some pus discharge. It necessitated radical surgery to be able to get the snare out. The section of the leg below the snare was very swollen. Despite the injury however, the animal was able to use the leg and prognosis looked favourable but the leg will have life-long lameness for the swelling will not resolve. The injury was cleaned and topically treated and systemic antibiotics given.