A handheld solution to a hidden problem?

In a roughly constructed pen in a remote village, a farmer inspects his cow. The animal has lost weight, is off its food and is coughing. The farmer knows the animal is sick but just how sick is it? And, if medication can be bought, how soon will he be able to tell whether the animal is getting any better. This animal is an important part of the family's security and the farmer is naturally concerned that he may well lose this valuable asset. As the farmer runs his hands down the back of the cow he searches for signs of further deterioration - with a little extra knowledge could this farmer determine the underlying cause of his animal's illness and therefore be in a better position to obtain appropriate treatment?

An anaemic approach?

In many regions, livestock can be affected by more than one disease at the same time. Parasitic diseases, such as tick-borne or helminth diseases are particularly common. The problem is compounded when the animal is suffering from the combined effects of two or more parasitic diseases. Generally, farmers are aware of the symptoms associated with these diseases but their knowledge is not sufficient to accurately determine the degree of illness. Existing techniques for the diagnosis of these diseases are costly and inappropriate in regions where trained veterinary staff are not available. However, the solution may lie in blood sampling used in conjunction with a directed approach to the clinical examination of the animal.

Anaemia, for instance, is a common consequence of many endemic cattle diseases. Thus, by haemoglobin levels it is possible to not only tell that an animal is unwell but repeated measurement can also determine whether it is responding to a given treatment. In addition, if farmers or community animal health workers are directed to observe the animal's general demeanour, such as appetite, condition of coat, respiration, evidence of diarrhoea etc., this can be combined with a measurement of anaemia to improve diagnosis of the most likely cause of illness.

Haemoglobinometers, (tools used to provide a digital reading of the level of anaemia in a drop of blood) are already used in human health, for instance, with people suffering from malaria - a protozoan parasitic disease which also causes anaemia. However, many of these instruments are too expensive to be used widely by animal health assistants and a simpler and less sophisticated approach is to examine a spot of blood on filter paper and to compare the result to a colour chart. Although relatively crude, it is possible that such measurements could be sensitive enough to provide the information required to improve diagnosis of livestock in resource-poor areas.

Testing tools and techniques

However, it is not the diagnosis that is in itself important. What is required is a best-bet diagnosis, rather than a conclusive diagnosis, which will improve the probability that the sick animal is given appropriate treatment. To this end a range of tools, including haemoglobinometers and filter paper techniques are currently being tested in Uganda and Kenya to evaluate their suitability for this purpose. And, to help with clinical observations, a simple low-cost tool, similar to a slide-rule, is being designed to provide a decision support system when making clinical observations. By moving the slide rule in answer to selected questions, the most likely diagnosis for an animal's illness can be indicated. The advantage, says Mark Eisler of the University of Glasgow, is that drug treatment can then be administered more or less immediately without the lengthy and expensive process required for laboratory tests.

In support of these tools, a survey of cattle has recently been conducted in south-east Uganda to determine the clinical signs and levels of anaemia associated with the diseases common in the area. By testing animals free of disease, blood samples have been able to provide an indication of normal values of haemoglobin in healthy animals and sophisticated laboratory tests have been used to confirm results from the field. This has provided verification of the clinical signs and anaemia levels likely to be found as a result of particular diseases or combination of diseases that are endemic in the region. With this information, it is hoped that within the next few years animal health workers will hold the information that will enable them to improve diagnosis of sick livestock. The most appropriate treatment can then be administered and, within a short period of time, it will then be possible to take repeated readings to confirm that the animal is well on the road to recovery and the farmer can be assured that his assets are protected.

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