East Coast Fever

East coast fever, a disease of cattle caused by the protozoan parasite Theileria parva and transmitted by the three-host tick Rhipicephalus appendiculatus (the brown ear tick), is a major constraint to cattle production in Eastern, Central, and Southern Africa. In Kenya it is the most important tick-borne disease and a major constraint in cattle productivity. This is due to the high morbidity and mortality it causes in susceptible herds, the cost of control of the vector ticks, and the cost of treatment of clinical cases. Animals that recover from the disease also suffer from reduced productivity which can be long term. The limited distribution of the tick and the disease to only East, Central and Southern Africa also means that the market for therapeutic drugs and acaricides is small. Therefore, drug companies are not keen on funding research and development of new drug and acaricide molecules when resistance occurs.

An Overview of Hard and Soft Ticks and Their Control Methods

Ticks are important ectoparasites of livestock in tropical and sub-tropical countries. They are responsible for the enormous economic losses both through the direct effects of blood sucking and indirectly as vectors of disease pathogens and toxins. Morphologically, ticks are classified into two families known as Ixodidae (hard ticks) and Argasidae (soft ticks). In this chapter, the authors provide a description of the soft and hard ticks. Emphasis is laid on the genera morphology, species, mammalian hosts, and distribution and the diseases transmitted by the ticks species. Various methods for controlling ticks and tick-borne diseases using chemicals are described. A broad range of chemical acaricides used for the control of ticks on livestock are described. Conventional methods and unconventional methods for applying acaricides to protect livestock against ticks are described. Alternative methods for tick control are described. Only the most important hard and soft ticks and associated diseases are discussed within the limits of this review.

Non-Tsetse-Transmitted Animal Trypanosomosis (NTT)

The non-tsetse-transmitted animal trypanosomoses are infections caused by three main mammalian trypanosome species, namely Trypanosoma evansi, T. equiprdum, and T. vivax. Their global distribution is much wider than tsetse-transmitted trypanosomoses and includes Africa and Latin America, Asia, and Euro-Asia. These trypanosomoses affect a very wide range of domestic animals and game and negatively impact on the development of the animal industry, thus directly affecting national economies and people's livelihoods.

Bovine Anaplasmosis and Control

Bovine anaplasmosis is one of the most important tick borne diseases of ruminants worldwide causing significant economic losses in the livestock industries due to the high morbidity and mortality in susceptible cattle herds. Bovine anaplasmosis, caused by Anaplasma marginale, is an infectious but non-contagious disease. The mode of transmission of bovine anaplasmosis includes mechanical (blood contaminated fomites (needles, ear tagging, dehorning and castration equipment), biological (tick bites) and transplacental (mother to fetus). Bovine Anaplasmosis occurs in tropical and subtropical regions worldwide. Cattle of all ages are susceptible to infection with A. marginale, but the severity of disease increases with age. The common clinical sign of bovine anaplsmosis includes; fever, anorexia, rapid loss of body condition, severe decrease in milk production, pale and icteric mucous membranes, increased heart and respiratory rates, muscle weakness and depression. Diagnosis of bovine anaplasmosis can be made by demonstration of A. marginale on stained blood smears from clinically infected animals during the acute phase of the disease, but it is not reliable for detecting infection in pre-symptomatic or carrier animals. Instead, serological demonstration of antibodies and confirmation of antigen with molecular detection tools are used for diagnosis. Anaplasmosis can be treated by administration of oxytetracyclines, however oxytetracyclines do not clear the parasite from carrier animals. Control measures for bovine anaplasmosis vary with geographical location and include maintenance of Anaplasma free herds, vector control, administration of antibiotics and vaccination. Intensive acaridae application to control ticks has a number of limitations, therefore, immunization together with strategic tick control is recommended for exotic and crossbred cattle. Further studies on epidemiology of bovine anaplasmosis is needed

Control of African Swine Fever and Avian Spirochaetosis

Ticks are distributed worldwide and have an enormous medical and veterinary importance owing to the direct damage they cause and indirectly as vectors of a large variety of human and animal pathogens. The family Argasidae (soft ticks) comprises five genera and with about 193 species. Among all the argasid ticks, only four Argas and two Ornithodoros species are competent to transmit diseases. This chapter describes the various ticks of the argasidae family, diseases they transmit, and strategies for their control. A description of the two important genera, Ornithodorus and Argas, that belong to the family argasidae are provided. Emphasis is on the mammalian hosts affected, tick species involved, morphological features (with relevant pictorials), geographic distribution, life cycle, and economic importance. A detailed description of the two most important diseases transmitted by argasidae ticks namely African swine fever (ASF) and avian spirochaetosis is given. Emphasis is laid on the historical background, epidemiology, clinical signs, and strategies for their control.

Canine Ehrlichiosis in Africa

Canine ehrlichiosis is an infection of canids causing a clinical disease in domestic dogs and asymptomatic infections in wild canids. Currently, the disease assumes a cosmopolitan distribution. This chapter summarises published information on the disease from across Africa. Some studies were able to demonstrate experimental infections in these canids. Different diagnostic methods, cell culture, direct microscopy, serology, hematology, and molecular methods were employed in different studies for detection of ehrlichiosis. Treatment of the disease mainly involved use of oxytetracycline, doxycycline, imidocarb disproportionate, and levamisole. In severe cases, management has involved administration of supportive therapy such as blood transfusion. Generally, though available, the information on different aspects of the disease in the Africa is scant and fragmented. There is still a need to generate more information on the epidemiology, diagnosis, clinical aspects, and treatment of the disease.

Overview of the Vectors and Their Role in Transmission of African Animal Trypanosomiasis

African animal trypanosomiasis (AAT) is a major constraint to livestock productivity, particularly in cattle and in camels. This chapter covers some general aspects of the arthropod vectors of animal trypanosomiasis, the tsetse flies Glossina spp., and to a lesser extent the biting flies. This chapter covers the classification, morphology, basic biology, and the eco-distribution of tsetse flies. The role of tsetse flies in disease epidemiology has also been reviewed. The elementary biology of these vectors is quite well known and elucidated. However, with advances in molecular and other biological techniques, new insights related to tsetse biology have been obtained. This chapter will revisit these basics and include some updated information emanating from research done in the recent past. The final part of the chapter is devoted to a brief discussion on biting flies, the vectors of T. evansi, which causes camel trypanosomiasis.

Use of Trypanotolerant Breeds

This chapter describes the meaning of trypanotolerance and its implication as used with trypanotolerant livestock that are known and studied for many years in West Africa. This trait is observed in many West African breeds of cattle that survive in areas of tsetse fly challenge where the humped zebu cannot. Small ruminants and wildlife also exhibit increased resistance to infection with trypanosomes. Trypanotolerance is viewed as a more sustainable and environmentally friendly approach to control of trypanosomiasis given the limitations of the present methods of control and lack of vaccine. Little work has been conducted with East African cattle breeds. The Kenyan Orma Boran (OB) has been studied since 1983 to enhance its conservation and utilization in East African region. Nucleus breeding herd of superior genotypes was multiplied in Galana Agricultural Development Corporation (ADC) and disseminated to trypanosomosis endemic areas of Kenya. On evaluation, performance of the crosses was comparable to that of other Borans. Challenges of adoption in pastoral area are presented.

Heartwater and Control

Heartwater (HW) is an acute, febrile, tick-borne disease of cattle, sheep, goats, and wild ruminants characterized by nervous signs and high mortality. The disease is caused by a rickettsia agent, Erlichia ruminantium, formally classified as Cowdria ruminantium. The disease is transmitted by several ixodid ticks of the genus Ambylomma. Chemoprophylaxis has been used as a method to facilitate the movement of heartwater susceptible stock into heartwater endemic areas while allowing them to acquire immunity by limited tick exposure.

Introduction of African Animal Trypanosomosis (AAT)/Nagana

African animal trypanosomosis (AAT), a livestock disease, also known as Nagana, tsetse fly disease, or tsetse disease, is a widespread tsetse-borne disease complex caused by unicellular protozoan parasites belonging to the genus Trypanosoma. It is one of the major constraints to the expansion of livestock rearing and livestock-based industries in Africa. It also constrains mixed farming, human health, and livelihood in tropical Africa. The tsetse fly is the major vector of the disease. Acute disease is characterized by marked depression, intermittent fever, anorexia, anemia, blood-tinged diarrhea, and adenopathy, sometimes petechiae on mucosa, abortion, and death if not treated. Diagnosis is made by observing trypanosome parasites by direct microscopic examination of blood, lymph nodes, edema fluid, or tissues. Treatment is by chemotherapy and chemoprophylaxis. Control is achieved through vector control treatment using available molecules and use of a few available trypanotolerant breeds of animals.