Veterinary Informatics and Epidemiology
ECFXPERT is an integrated computer model designed for investigation of Rhipicephalus appendiculatus tick populations, the disease East Coast fever (ECF) and its control. The model runs on IBM compatible micro-computers and requires 640K RAM and a VGA colour monitor. The model is designed to be used by a wide range of users from many disciplines in helping to answer differently motived questions concerning ticks and the disease. A tick ecologist, for example, may be interested in investigating the factors that control various seasonal patterns exhibited by ticks, or the consequences of global warming on tick populations. A parasitologist may wish to explore the effects and importance of carrier status in recovered cattle. Alternatively, a farm manager might be interested in determining the most effective and economical method of disease control at a given site. ECFXPERT provides the facility to explore these questions. The model can also be used as a planning tool to determine effective research programmes by performing computer experiments to assess the suitability of a research thrust and to aid the design of experiments.
The computer package is intended for users with little computing knowledge and provides a user-friendly environment for performing computer experiments. Screen editors allow the default environmental inputs such as climate, grass length and herd structure for different sites to be changed. The program contains comprehensive data on ticks and ECF, providing a learning facility for users with limited knowledge of the disease. On request, help messages appear In windows on screen and keyboards indicating areas where more information is available appear highlighted. This hypertext-like facility allows the user to progress through a series of help screens, increasing the depth of knowledge displayed on a particular aspect of the disease. In a similar way, references to relevant literature and scientific papers are available.
The integrated model contains four simulation models a tick method, an ECF model, a dipping model and chemotherapy model. The tick model is for the investigation of tick populations alone. The ECF model investigates the incidence of disease in cattle by modelling tick, parasite and herd interactions. The dipping and chemotherapy models looks at the effect of tick and parasite control of the incidence of disease. An important aspect of these simulation models is that they are based as much as possible on empirical data and expert findings and opinions extracted from the ECF literature covering 80 years of research.
Output screens provide graphical plots of numbers of ticks in each stage each day of the year, and dot plots of the weekly changes in the structure of the herd and the numbers of cattle to become infective and die. Simple univariate summary statistics can be viewed during a simulation, and a comprehensive summary of data describing a particular simulation is stored in an output file for later study.
Agricultural production in Africa has attracted much worldwide interest, due to the problems caused by past and present food shortages. The majority of people living in Africa are subsistence farmers and, due to the lack of long term agricultural planning, periods of environmental mishap, such as drought, can become major disasters. The development of the livestock industry represents one area where aid is being directed. Disease places a large restraint on such development. East Cover fever (ECF) has been described as the second most important African cattle disease after trypanosomiasis. The disease is caused by the protozoan parasite Theileria parva, which is transmitted to cattle by the three host tick Rhipicephalus appendiculatus. The prevalence of ECF is normally restricted to central and eastern Africa - regions where the cattle hosts, Bos taurus and Bos indicus, the tick vector, and the parasite share the same geographical location. ECF is a major economic threat, putting at risk the lives of about 25 million cattle in Burundi, Kenya, Malawi, Mozambique, Rwanda, Sudan, Tanzania, Uganda, Zaire, Zambia, and Zimbabwe. The disease has been reported to be the cause of half a million deaths in cattle per year in East Africa. In Kenya alone, it has been estimated that 50-80% of the national cattle population, currently around 10 million animals, are exposed to the tick, and of these animals 1% die of ECF each year.
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