Haemonchosis is an acute problem in India. Three species of Haemonchus occur. These are H. contortus (Rudolphi, 1803) which occurs in sheep, goat, cattle, buffalo and other ruminants; H. longistipes Railliet && Henry, 1909 occurring in camels and H. similis Travassos, 1941 in cattle. Seasonal fluctuation of H. contortus occurs, with infection being more frequent in autumn ≻ summer ≻ winter ≻ spring, and infection in sheep and goats has been reported to be 100 %. Various aspects of haemonchosis have been investigated. However, the fundamental and the most challenging areas in Haemonchus research remain almost untouched. In order
to forecast the development of haemonchosis, epidemiological studies should be undertaken on the prevalence, distribution and seasonal incidence of the worm to understand the effects of climatological factors like rainfall, humidity and temperature. The sparse and inadequate studies of metabolism need to be extended to other areas of Haemonchus biochemistry to provide additional possibilities for exploration of hostparasite differences. Clinical haemonchosis in sheep, goats and other
ruminants should be studied in order to calculate losses caused by mortality and the cost of anthelmintic medication. Most anthelmintics are expensive, and are not easily available to our farming community, therefore a search for many more indigenous anthelmintics (such as Wopell, Krimos, Sonex etc) must be made. Detailed knowledge of the mode of action and route of entry of anthelmintics at the molecular level could also be beneficial, particularly when the strains of H, contortus have been identified as resistant to some anthelmintics. The prospects of producing a vaccine against H. contortus should be explored. Attempts in this field have already been made by overseas workers (see Clegg && Smith, 1978) and in India too, work has been undertaken at Kerala (Sathianesan, personal communication). Therefore, because of its economic importance and wide distribution, H. contortus provides fascinating research material particularly in the warmer regions of the world.