Dairy sheep and goats play an important role in building economy and providing livelihood in many parts of the world but at the same time they are affected by many diseases particularly parasitic problem. Among parasitic diseases, Haemonchus, Oesophagostomum, Trichostrongylus and Telodorsagia are the main genera of gastrointestinal nematodes that are important for small ruminants andHaemonchus (H.) contortus is the most dangerous because of its economic significance. Usually the infection with H. contortus causes severe anaemia and hypoproteinemia which ultimately leads to pale mucus membranes, reduced productivity, depression and death in severe cases.For control of H. contortus, traditional practices are adopted to deworm the entire flock according to the recommended schedule or whole flock is treated when only a single animal shows the signs of haemonchosis. There are reports of development of anthelmintic resistance in sheep reared by commercial farms as well as small holders due to excessive and un-necessary use of commercial anthelmintics. Anthelmintic resistance has been developed against all broad spectrum anthelmintics including levamisole, benzimidazoles and avermectins including doramectin, ivermectin and moxidectin.The problem of anthelmintic resistance has been observed even in the developed countries like Australia where profitable sheep industry is at risk of parasites by causing disturbance in the economy. Thus, there is need of alternate strategies to control the nematode infections and building the economy. Furthermore, the key issues of increasing animal production to meet an ever increasing demand of food, is only possible by addressing the problem of anthelmintic resistance.
In the present scenario of anthelmintic resistance, there is need of targeted selective treatment (TST) for better farm management to avoid the problem of anthelmintic resistance and to maintain the population in refugia.The TSTis a technique to maintain some population of worms in refugia by only treating those animals which suffer from production and health losses due to parasites while leaving other animals untreated in the flock.Increased anthelmintic resistance in South Africa and other countries led different scientists to work on the principle of TST and ultimately FAMACHA system was developed as an indicator of TST. FAMACHA system is an eye color chart and it is named after its originator Dr. Faffa Malan (FAffa MAlan CHArt). This card was developed in South Africa for sheep to detect anaemia due to H. contortus.The FAMACHA system has five color categories for comparison with the haematocrit values which are taken as the gold standard to evaluate the anaemia. It is a common observation that during anaemia due to H. contortus, the color of the mucus membranes of eyelids of sheep changes from red (healthy) to pink (anaemic) and sometimes white (severely anaemic). These colors are matched with the haematocrit values which are taken as the gold standard and these values differ in different experiments.The FAMACHA system is used in such a way that the color of the mucus membranes of lower eyelids of sheep is matched with the colors on the FAMACHA card and thus it is given the score “1” which means healthy and “5” which indicates severely anaemic animal or in need of treatment. In this system, only those animals are given treatment which fall in the categories of “4” and “5” or in other words they are in danger of dying due to anaemia caused by H. contortus.
This eye color chart has been used in different countries with different production systems of small ruminants where H. contortus is main GI nematode. The results observed during these studies have shown that this system is helpful in selective treatment of those animals which are really in need of anthelmintic treatment. It has ultimately helped to reduce the number of treatments and to maintain a particular population of worms in refugia by avoiding the un-necessary treatment of healthy animals. Besides South Africa where this card was developed, it has also been tested in many other countries including United States, Malaysia, Ethiopia, Kenya, Namibia, Germany, Italy, France, Cuba, Guadeloup, Brazil and Pakistan. FAMACHA card in now distributed worldwide and available in six major languages.
The FAMACHA system has many advantages like it satisfies the requirement of a diagnostic test against haemonchosis and reduces the uncertainty about the status of anaemia in animals. This system is an inexpensive and simple method in which the color of the lower eye lids of sheep and goats is matched with the chart that has a rage from red (healthy) to almost white (anaemic). The eye color chart has the advantages that only 20-30% or less animals are being treated, ultimately treatment cost is reduced, development of anthelmintic resistance is slowed down by keeping a portion of parasites in refugia and most susceptible animals can be removed from the flock to improve the genetic status.The system is useful in selection of resistant and/or resilient animals by record keeping where the animals requiring more treatments are culled while others with less need of treatment are retained.Although FAMACHA system has been proved to be a useful tool against haemonchosis but it has certain limitations like its application only against haematophagus parasites and its training for the farmers by convincing them about the advantages of its use. FAMACHA system works only against anaemia due to H. contortus but there are many factors that can cause anaemia. Thus, it is recommended that FAMACHA system should be validated before its use because there could be local issues like different geographical region, breeds and climate differences, etc.