Testing for clinical anaemia caused by Haemonchus spp. in goats farmed under resource-poor conditions in South Africa using an eye colour chart developed for sheep

A novel clinical assay for the assessment and subsequent treatment of Haemo nchus infection in sheep to slow down the development of anthelmintic resis tance - the FAMACHA((C)) system has been developed, tested and validated in South Africa. The system is based on a colour chart with five colour categ ories depicting varying degrees of anaemia that are compared with the colou r of the mucous membranes of the eyes of sheep. The animal is then scored f rom severely anaemic (pale) through anaemic to non-anaemic (red) and those animals considered in danger of succumbing to the effects of haemonchosis a re treated. This method was tested in goats farmed under resource-poor cond itions in South Africa. Analyses in goats performed during the summers of 1 998/1999 and 1999/2000 show a test sensitivity of 76 and 85%, respectively, meaning that the system may be used to identify correctly 76-85% of those animals in need of treatment with an anthelmintic. However, the test specif icity remains low at 52-55%. This means that a large proportion of those an imals that would not require treatment would in fact be treated. However. w hen the use of the FAMACHA((C)) system is compared with conventional dosing practices where all the animals are treated. using the FAMACHA((C)) system would result in a large proportion of the animals being left untreated. Th e untreated animals are then able to deposit the eggs of anthelmintic-susce ptible worms on the pasture, while the treated ones should pass very few ov a, given an effective anthelmintic. This maintains a reservoir of susceptib le larvae in refugia, and should slow down the development of anthelmintic resistance. The validation of the FAMACHA((C)) system for goats for use by resource-poor farmers, which this paper describes, may have wide applicatio n in the tropics and subtropics of sub-Saharan Africa and elsewhere. (C) 20 01 Elsevier Science B.V. All rights reserved.