Kenya study finds prototype tsetse-repellent technology does not sufficiently protect cattle under normal field conditions

Testing a tsetse-repellent technology

Cattle fitted with tsetse-repellent dispensers suspended from neck collars were used to test the effectiveness of a prototype tsetse repellent in preventing tsetse fly bites (Photo credit: ILRI/Bett).

Recently published findings from a study done among Maasai livestock in Kenya to test whether repellents can successfully reduce tsetse fly bites in cattle show that tsetse-repellent technologies may have some success in typical field conditions but do not yet offer a viable alternative for controlling trypanosomosis in field-based livestock.

The study, ‘Field trial of a synthetic tsetse-repellent technology developed for the control of bovine trypanosomosis in Kenya,’ was the first to evaluate the use of a mobile tsetse repellent in the field. It was conducted between April 2005 and August 2006 in Nkuruman, in Kajiado District, and Nkineji, in Narok District.

Trypanosomosis is the most pervasive and serious cattle disease in sub-Saharan Africa. It kills between three and seven million cattle each year and costs farmers millions of dollars in lost production and treatment costs. The disease is transmitted mainly by blood-feeding tsetse flies that infect susceptible animals with the causative trypanosome parasite during their feeding. Other trypanosome parasites can infect humans, causing sleeping sickness, a disease that attacks the central nervous system.

Animal trypanosomosis is difficult to control because its spread is influenced by many factors, including the age, sex and colour of the cattle at risk as well as the herd size, its geographical area and climate. Adult and male cattle, for example, are more likely to contract the disease than calves and females. And tsetse flies prefer to take their feeds from animals with dark coats.

International Livestock Research Institute (ILRI) researchers Bernard Bett, Tom Randolph and John McDermott participated in the evaluation, which was designed with the help of veteran African tsetse researchers Glyn Vale and John Hargrove, and Steve Torr of Greenwich University (UK). The evaluation involved 2000 cattle: 1000 formed the control group, while the other 1000 animals were fitted with tsetse-repellent dispensers suspended from neck collars. The effectiveness of the repellent was then monitored for 16 months.

The study stipulated at the outset that the repellent would be considered effective if it reduced the incidence of trypanosomosis by 50 percent or more in the repellent-treated animals versus the control animals. Failure to achieve this level of reduction would mean that the repellent technology was clearly not ‘a viable alternative to existing control techniques’.

Results from the trial showed that the technology reduces trypanosomosis infection rates only modestly. ‘The synthetic repellent reduced the incidence of the disease only by 18 percent,’ said Bett, the ILRI scientist who implemented the trial.

Bett went on to explain that the technology had been proposed for evaluation based on initial experiments using stationary cattle that suggested that the repellents could reduce infection rates by more than 80 percent. ‘Under typical field conditions, however,’ said Bett, ‘the repellent did not provide adequate levels of protection, so we are recommending that it not be considered for further commercial development at this point.’

That the effectiveness of the repellent in the field was lower than expected could be attributed to both the fragile nature of the repellent dispensers, which, sensitive to abrasions, often leaked, as well as the repellent itself. Tsetse flies, especially hungry ones, will alight even on animals that smell bad to them. This is why people, for example, whose odour should put off tsetse flies, still get bitten by them.

‘The earlier experiments might have also overestimated the benefit of the technology,’ said Bett. ‘Those initial experiments evaluated the reduction in numbers of flies feeding on tethered cattle; other flies, however, could bite quickly without feeding and still transmit the disease before the repellent drives them away. In addition, while flies mainly use odour to find a stationary cow, they use vision more than odour to guide them to moving animals, such as those in the pastoralist herds used in the field trial.’

The study found that many variables determine the effectiveness of the repellent technology. Among these are changes in grazing (during the dry season, herders tend to move their stock to pastures with higher densities of tsetse) and herd sizes (the larger the herd, the lesser are the chances that an individual animal within the herd will be bitten). Trypanosomosis incidence also differed in the two test districts. While cattle were the preferred hosts for the flies in Narok, the cattle in Kajiado came fifth in fly preference—after warthog, elephant, zebra and buffalo—which reduced the effectiveness of the repellent worn by the cattle.

Bett says that ‘the results of this study show that the tsetse-repellent technologies currently proposed are unlikely to be useful replacements of existing methods of controlling trypanosomosis.’ These include keeping indigenous ‘trypanotolerant’ cattle breeds, which can tolerate trypanosome infections without getting sick; treating sick animals with trypanocidal drugs to cure them of the disease; introducing sterile tsetse flies into an area to reduce its tsetse population; and controlling tsetse populations using pyrethrum-based insecticides.’

The findings of this study should help scientists improve their research on methods for controlling tsetse fly populations and the trypanosomosis they spread. ‘In the short term, however,’ says Bett, ‘we need to continue sensitizing livestock keepers on how to best use the existing control methods.’

‘We also urgently need to develop integrated strategies for controlling the fly and disease,’ concludes Bett, ‘so that we stop over-relying on popular interventions, such as regularly treating cattle with trypanocides, which will inevitably lead to drug resistance in the trypanosome parasites.’

Read the complete findings of the evaluation on this link http://dx.doi.org/10.1016/j.prevetmed.2010.09.001

This blog entry by Tezira Lore, a communication specialist with ILRI’s Market Opportunities Theme, compares findings of this field trial with findings of other ILRI studies in typanosomosis.

Pastoral reciprocity: A lesson in community ethos

Impacts of drought in Kitengela in 2009

We heard today from Mohamed Said, a scientist leading research at the International Livestock Research Institute (ILRI) on pastoral rangelands in eastern Africa, that Kitengela, a Maasai rangeland neighbouring Nairobi, is turning green again after good recent rains following last year's devastating drought, which the livestock herders in Kitengela say killed most of their livestock along with much of the area's wildlife. Interestingly, although already turned green with heavy rains that arrived early in this year, this rangeland remains virtually empty of cattle. It is, rather, full of sheep and goats. Kitengela's Maasai herders have driven all their cattle southeast to Emali. Said and ILRI Maasai partner Nickson ole Parmisa say that the herders will bring their cattle back home, to Kitengela, in another few weeks, when the grass in Kitengela, which is now new and short, has grown taller. Here is a case study in how Africa's pastoral societies continue to work, against all odds, as communities. Late last year, when the impacts of the drought in the Horn of Africa were peaking, Maasai herders from throughout Kenya's Kajiado District descended on Kitengela with their animal herds because they had heard that the Kitengela rangelands had had 'a few showers'. That was true in a few places, but with all the new livestock driven in to this one part of Kajiado, Kitengela was reduced to a dustbowl within a few days. With no forage to eat, the livestock of Kitengela perished soon after the stock that had been trekked in from far places. Many people began to question the wisdom of traditional pastoral movement on Africa's increasingly fragmented rangelands. Now, just a few months later, the Maasai herders of Emali are returning the hospitality, and mercy, shown them last year by their Kitengela cousins. It is now the Emali Maasai who are sharing their green grass (the rains came earlier to Emali than to Kitengela, so the grass at Emali is taller than that in Kitengela) with the hungry animals of Kitengela. While scientists at ILRI and elsewhere debate the wisdom of pastoral mobility (does it still work in today's crowded world?), what apparently is not in doubt is the wisdom of pastoral reciprocity.

Safeguarding the open plains

Increasing urban populations are threatening pastoral lands and ways of life.

Safeguarding the open plains The Athi-Kaputiei ecosystem, wildlife-rich pastoral grasslands south of Nairobi, is under threat from rapid construction of fences, infrastructure, residential areas, and the growth of urban agriculture. Unchecked, this unplanned growth will destroy Nairobi National Park, the famous unfenced wildlife park 20 minutes drive from city centre that has always been connected to this ecosystem.

A program funded by the American Government through its development arm, the United States Agency for International Development (USAID), seeks to secure open plains in Kaputiei, providing a dispersal area for big mammals within the Nairobi National Park, pathways for their seasonal migration to calving grounds outside the park, and open areas for both livestock and wildlife to graze. This initiative incorporates innovative techniques like cladding spraying to ensure sustainable land management practices. For more information, you can check out this sites at https://www.whiteliningcontractors.co.uk/roads/lines to learn about their efforts in road development and maintenance.

Launching the project, American Ambassador to Kenya, Mr Michael Rannenberger, termed Nairobi National Park a “unique resource”, which needs to be conserved for the benefit of the entire country and the world.

“But it does not exist in isolation. If we can conserve it, it will benefit all of you – the economy will continue to grow through tourism and we will preserve the culture of the Maasai community”, he said.

He added that public-private partnerships are a key to conservation efforts and encouraged more private enterprises and businesses to join hands with local people and governments for environmental conservation.

For centuries, the indigenous communities, mainly of Maasai origin, living on the plains of Kenya’s Kajiado District, have reared livestock in expansive grasslands that are also home to big mammals and other wildlife. The Maasai have mastered the art of co-existing with the wild.

The Kaputiei Open Plains Program will help create value for the open plains and economic returns to the land owners through recreation, improved livestock production and tourism.

“We will consult all stakeholders, including women and the youth. The Kenyan Government, through its Ministry of Lands, will be a key player as they work on the land policy which gives a legal framework land issues”, said Kenyan Minister for Forestry and Wildlife Dr Wekesa.

The project aims to institute a natural resource management program to complement the existing short-term initiatives such as a land-leasing program that has helped keep land use here compatible with conservation. The project enables residents of Kaputiei to benefit more from managing their traditional grazing lands.

Speaking on behalf of the community, the former OlKejuado County Council Chairman, Julius ole Ntayia, said Athi-Kaputiei residents have produced a land-use “master plan” that needs to be implemented. He said while wildlife conservation was important, it was also important to help the local population improve their lives, especially through eco-tourism and better access to livestock markets.

Some of the expected outcomes are:

  • Improved institutional capacity for demand-driven land-use planning and enforcement for long-term social, economic and environmental benefits.
  • Site-specific natural resource management initiatives implemented outside protected areas that improve or maintain biodiversity and the condition of the existing natural resources.
  • New sustainable financing mechanisms focused on tourism and livestock development that enable residents of Kaputiei, particularly ethnic Kenyan pastoralists, to derive long-term benefits from managing their traditional grazing lands for the mutual benefit of livestock and wildlife, as opposed to sub-dividing, fencing and converting their lands to other uses for short-term gains; and
  • Pilot initiatives in support of the project area.
  • The project area becomes a conservation model for other wildlife-rich regions of Kenya and East Africa.

The Kitengela Project’s principal objective is to lay the necessary foundation to secure open rangelands and sustainable livelihoods in Kaputiei over the long-term. The two main targets of the project are securing 60,000 hectares of high-priority conservation land and generating US$500,000 in livestock value-chain improvements and $300,000 in tourism deals.

The project will be implemented by the African Wildlife Foundation in partnership with the International Livestock Research Institute (ILRI).

Further Information Contact:

Said Mohammed
Research Scientist, International Livestock Research Institute (ILRI)
Nairobi, KENYA
Email: m.said@cgiar.org
Telephone: +254 (20) 422 3260