With rains being experienced in most parts of the country and especially here in Tsavo, there were no cases reported in April. This is consistent with the previous years when we hardly get any cases in the wet seasons. Normally in the rainy season, the local communities get involved in their farms and thus reduced incidences of poaching for bush meat. The animals also get widely dispersed as there is water and pastures/browse deep inside the parks and become difficult to see. Injuries to wildlife resulting from conflicts with man are also reduced because such incidences are few during these seasons.

Most of the month was spent with a veterinary team from Nairobi doing a disease sero-surveillance exercise in the entire ecosystem. The diseases of interest were those that are transmitted between wildlife and livestock and impact negatively on wildlife, livestock and the economy. Of great concern amongst these diseases was rinderpest, which in previous years caused a big mortality in buffaloes, Kudus and giraffes amongst other susceptible species in the ecosystem. The Tsavo ecosystem is critical as far as the surveillance of this disease is concerned because of the interaction with livestock from the neighbouring communities as well as from the Somali ecosystem. The latter which encompasses the North-Eastern and Eastern provinces in Kenya as well as Somalia, is classified as a rinderpest infected zone because of lack of rinderpest control strategies in Somalia. There has been a worldwide campaign to eliminate rinderpest but the virus continues to circulate in this ecosystem. The Somali pastoralists lease most of the ranches around Tsavo East and West national parks for dry season fattening of their livestock for local and export markets. The surveillance has been going on for several years now and is an international requirement for Kenya and other countries in the region before they can apply for rinderpest free status. The exercise in the Tsavos is part of an ongoing surveillance in the entire country involving both livestock and wildlife. It is funded by the Pan-African Campaign on Enzootics (PACE) under the auspices of the African Union-International Bureau for Animal Research (AU-IBAR).

The objectives of the exercise in Tsavo was to examine, sample and establish the disease status in key buffalo herds and other susceptible species in the parks and adjacent areas. It also aimed at establishing the status of herds confirmed to be negative in the last sampling done in September 2003.

Sampling entailed immobilisation of susceptible species either from a vehicle or a helicopter. Buffalo herds sampled by helicopter would first be located by a fixed wing light aircraft and the GPS coordinates taken for each location. The helicopter with two vets would then be called in to do the darting. 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 Palmer Cap-Chur® darting rifle. After induction, the vets would be dropped. They would clinically examine the animals, take blood samples, age and sex the animals before reviving them with the appropriate antidotes before being picked by the helicopter. Aging was done using the eruption pattern of the incisor teeth and horn development/shape. Ages selected were >1 year and < 6 years to avoid complications of maternal immunity or previous exposure which was in 1999. However, we selected most animals born after the last sampling in 2003 to assist us peg a date of any existing virus circulation.

Buffalo herds sampled from the ground were located by vehicle. The other species were located and darted from a vehicle. Warthogs were captured with a net and restrained physically during sampling. The Dan-Inject darting system was used for the vehicle darting.

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.

Seventy-one buffaloes were sampled in the ecosystem; 40 in Tsavo East from six herds and 31 in Tsavo west from seven herds. Thirteen giraffes and nine waterbucks were sampled in Tsavo East while one warthog was sampled in Tsavo West. There was no mortality experienced.

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.

Samples collected included whole blood from which sera was extracted by centrifugation after >6 hours of clotting. It was placed in 2ml Cryovials in 7 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 regional and international rinderpest diagnosis labs at Muguga and CERAD in UK respectively. Also collected was EDTA blood to establish the general health profile of the animals sampled and also for extraction of the Buffy coat for virus isolation.

Sampling was done in areas where wildlife are in close contact with pastoralist livestock, especially the Somali cattle which are fattened in the Taita ranches. In the recent past, there has been an increase in the number of livestock in the ranches. This coupled by the dry spell that was experienced before the current rains have led to increased incursions into the parks. There being no proper control of livestock movement from Garissa and other areas in Eastern province and Kajiado, the pastoralists pass through the parks to access the ranches, a scenario that further enhances the livestock-wildlife interaction in the area. The target areas were the following:

Tsavo East: • Ndii/Irima area: Wildlife here interacts with Taita livestock from the adjacent Mbololo, Ndii and Tausa areas. A buffalo herd that utilises this area was not found. Three waterbucks were sampled at Irima • Ndara/Ngutuni area: Interaction of wildlife is with Somali and Maasai livestock from the adjacent Sagalla, Maungu and Ndara ranches as well as Maungu township. A herd of buffaloes was sampled at Ndara as well as four giraffes; two at Ndara and one each at Maungu and Ngutuni • Aruba/Satao area: Interaction is with Maasai and Somali livestock from the same ranches as above. A herd of buffaloes was sampled near Aruba. Also sampled were giraffes at Aruba and Dika plains • Bachuma area: Interaction is with Somali and Maasai livestock from Taita, Mutondo and Dakota ranches. There was no buffalo herd found in the area but three giraffes were sampled as well as three habituated buffaloes at Taita ranch. • Galana/Sala area- Interaction is with Somali cattle from Galana and Kulalu ranches and Livestock Marketing Division. Three herds were sampled; one at Sala Hill and two at Mfupa Ndovu at the Northern shores of Galana River. Also sampled were a giraffe and three waterbucks in the area • Voi area: A buffalo herd was sampled at Kanderi. It was thought that this is the Voi herd which has moved further down into the park following good rains around Kanderi. No good rains had been experienced around the park headquarters at the time this exercise was undertaken. This herd interacts with Taita livestock. Also sampled were three waterbucks near Voi Safari Lodge • Punda Milia: Interaction with livestock is minimal as it is too interior. Secondary interaction with other wildlife that has interacted with livestock is possible in the dry season when animals move towards Galana River in search of water after water points dry in other areas. A buffalo herd was located but it was too shy with a big flight distance and attempts to dart with vehicle were not successful. There were no enough helicopter hours to use for this herd. Other species were also too shy and none was sampled • Ithumba/Tiva (Northern area) - Interacts with Kamba and Orma livestock. Areas not sampled due to limitations of the helicopter hours

Tsavo West • Komboyo/ park headquarters: Interaction is with Kamba cattle. The resident buffalo herd was not found. It was not possible to sample other species due to thick bushes • Finch Hattons/Kitani/Iltilal (Western border): Wildlife interacts with Maasai cattle. A buffalo herd was found and successfully sampled • Ziwani area: Interacts with Maasai, Taveta, and Kamba livestock. Three buffalo herds were sampled at Mbuyuni, Loosoito and Murka areas • Lake Jipe: Interaction is with Maasai livestock as well as livestock from Tanzania. Buffalo herds have moved Northwards after the rains. One herd was sampled near Maktau and another at Luarenyi ranch -L. Jipe cut line. Both these herds could have interacted with Somali cattle from the nearby ranches • Kasigau//Kanjaro/Kavuma/Kishushe areas: Interaction is with Somali cattle. No buffalo herds were found in these areas • Salt lick/Taita Wildlife Sanctuary: Interacts with Somali livestock and Taita cattle from Luarenyi, Kasigau, Mkuki and Mgenyo ranches. No herds were found in the area

We acknowledge the excellent cooperation of all the team members that made this work very successful. We also thank the respective park managements for their hospitality and support, as well as the support and fruitful discussions with the respective research scientists in both parks. We also sincerely thank PACE through their wildlife office for the financial support and cooperation.

The Mobile Veterinary Unit operated by The David Sheldrick Wildlife trust working with the The Kenyan Wildlife Service and funded by Vier Pfoten