How to win the war against tsetse fly

How to win the war against tsetse fly

Sleeping sickness is the scourge of sub-Saharan Africa where, according to the World Health Organisation and the United Nations Food and Agriculture Organisation, an estimated 50 million people and 48 million cattle are at risk of contracting the disease. The disease, which is caused by blood parasites, is spread through the bite of the fly, commonly called tsetse fly. It affects both humans and animals, particularly cattle.

The disease in humans causes fever, convulsions, coma, and even death if left untreated. Because the initial symptoms resemble malaria, it’s often not detected early enough, and the drugs used to treat the second stage of sleeping sickness can be toxic enough to kill the patient. Two types of the disease occur in humans, namely, the Gambian Sleeping Sickness, generally a chronic and wasting disease, confined almost predominantly to Central and West Africa and the Rhodesian Sleeping Sickness, a rapidly fatal disease, found mostly in Eastern and Southern Africa. 

The disease in animals, particularly cattle, called Nagana, has similar symptoms to those of humans apart from convulsions.  In both humans and livestock, the disease manifests in ill health, shortage of farm labour, food insecurity and rural poverty. One of the worst characteristics of poverty is its tendency to self-perpetuate.

Beyond its impact on humans and livestock is its impact on African agriculture and the livelihood of the rural population in the affected countries.  The fly and the disease influence where people decide to live, how they manage their livestock and the intensity and the mix of crop agriculture.  The combined effects result in changes in land use and environment which may, in turn, affect human welfare and increase the vulnerability of agricultural activity.

In Nigeria the situation is particularly alarming.  Here, the tsetse fly population is so widespread it is estimated to cover about 80 per cent of the country’s total area.  Much of this land is suitable for both crop and livestock production but it is rendered unusable by the deadly pest. This, in turn, has a negative impact on the country’s ability to produce enough food, making hunger and malnutrition a sad but present reality.

Land reclamation from tsetse fly commenced during the colonial era when the major concern was Human Sleeping Sickness, so that at independence in 1960, the battle against sleeping sickness in humans and in livestock, mainly in the northern part of the country, was half-won.  While the post-colonial era brought its challenges, the battle against sleeping sickness and livestock trypanosomosis remained a priority concern. 

Thus, between 1955 and 1978, Nigeria carried out easily the most successful tsetse fly campaign (in terms of size and level of success) in Africa, with over 200,000 sq km of tsetse infested country cleared of the pest by ground spraying and helicopter. This feat was achieved because the campaign was well-organised, enabling crop and livestock farmers to thrive and expand into areas previously denied them because of the threat of tsetse fly.  In 2003, tsetse flies were still absent from reclaimed areas due to environmental changes – expanding human population and agricultural activities.

Unfortunately, Nigeria relaxed its reclamation work and many of the areas reclaimed from tsetse fly has reverted to infested areas with resurgence of the disease not only of livestock, particularly cattle, but also humans, especially in new areas where, previously, the Gambian sleeping sickness was not a threat, namely in Delta State.   Because the acute form of sleeping sickness, the Rhodesian type, does not exist in Nigeria, the approach to control is by case detection and treatment. 

Because of the toxic nature of the drug in use and the need for long-term treatment, patients who are sick with sleeping sickness tend to be unable to stand the drug treatment regimen, dropping out midway in the treatment process.  Apart from this drawback is the stigma associated with a disease that many ignorant people regard as incurable and capable of being passed from one person to another by contact when, in fact, this is untrue.

Most efforts to control Nagana used by farmers focus on treating livestock with trypanocidal drugs, either as a treatment for sleeping sickness or as a preventative measure.   These drugs can cure the disease, but they don’t always stop miscarriages or raise an animal’s productivity level back to normal.  Plus, using drugs too often can cause the parasite to develop resistance, which has already begun to appear in most areas of the country.  

Farmers can also use traps and targets which reduce the tsetse fly population density, but this requires deployment of thousands of traps to cover a region.  This is expensive, especially when so many traps are stolen or destroyed by fires.  Farmers are encouraged to use insecticide pour-ons, sprays and dips on their livestock, but these are short-term solutions which must be repeated frequently.  Many farmers don’t apply the insecticides consistently and with the necessary frequency, which leaves any exposed animals vulnerable to the bite of tsetse flies and, therefore the disease.

Recently, the Federal Government of Nigeria voted a substantial amount of money to kick-start the resuscitation of the tsetse reclamation campaign, under the PATTEC (Programme Against Tsetse Fly and Trypanosomiasis Campaign), an initiative of the African Union Organisation designed to rid the continent of Africa of the menace of tsetse fly and trypanosomosis.

Experience has shown, however, that no single technology or approach will result in a sustained removal of tsetse flies from an area.  The Nigerian government must make its efforts to reduce and ultimately eliminate Nagana a priority—and quickly.  An integrated, countrywide approach with sufficient funds to sustain it is needed.  Recognising that government resources and manpower are limited, systematic approaches and sequencing of priorities will be key to success.

Proper training of farmers is also integral to success. Farmers need to know what control options are available and how to use them effectively.  They should be encouraged to keep their livestock in pens whenever possible to reduce the animals’ exposure to tsetse flies and other pests.   Farm families should be taught how to distinguish a tsetse fly from a less harmful species, and they need to understand that sleeping sickness can and should be treated by a doctor.

Sleeping sickness can be reduced in Nigeria.  In some parts of Africa it has even been eliminated.  The success recorded in eliminating the tsetse fly in some parts of Africa gives hope that it can also be done in Nigeria.

A successful eradication programme was completed in 1997 on the island of Zanzibar in East Africa.  Following a three-year fly-suppression campaign followed by release of sterile insects, the tsetse flies were eradicated and no case of sleeping sickness has since been reported on the island.  A study, six years after eradication, found that milk production had tripled, local beef production had doubled and the use of animal manure for crop farming had increased five-fold. 

Similarly, on the Loos Islands off the coast of Guinea, an integrated eradication campaign was launched in 2006 and, today, the tsetse fly population has been reduced to non-detectable levels.  Likewise, a recent success story has come from Botswana in which country has been successful in clearing the tsetse fly from the Okavango Delta region, using sequential aerial application of low dosage, non-residual insecticides as aerosols.  A similar approach has also achieved some success in the Caprivi area of Namibia based on a joint venture campaign.

While the road may be long and hard, Nigeria should aspire to be more like Zanzibar, Loos Islands and Botswana — nations with healthy citizens, robust and productive livestock, and a plentiful supply of nutritious food that will be natural outcomes if the tsetse fly problem is eliminated.

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