A.F. Vatta

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 Haemonchus infection in sheep to slow down the development of anthelmintic resistance--the FAMACHA system--has been developed, tested and validated in South Africa. The system is based on a colour chart with five colour categories depicting varying degrees of anaemia that are compared with the colour of the mucous membranes of the eyes of sheep. The animal is then scored from severely anaemic (pale) through anaemic to non-anaemic (red) and those animals considered in danger of succumbing to the effects of haemonchosis are treated. This method was tested in goats farmed under resource-poor conditions in South Africa. Analyses in goats performed during the summers of 1998/1999 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 specificity remains low at 52-55%. This means that a large proportion of those animals that would not require treatment would in fact be treated. However, when the use of the FAMACHA system is compared with conventional dosing practices where all the animals are treated, using the FAMACHA system would result in a large proportion of the animals being left untreated. The untreated animals are then able to deposit the eggs of anthelmintic-susceptible worms on the pasture, while the treated ones should pass very few ova, given an effective anthelmintic. This maintains a reservoir of susceptible larvae in refugia, and should slow down the development of anthelmintic resistance. The validation of the FAMACHA system for goats for use by resource-poor farmers, which this paper describes, may have wide application in the tropics and subtropics of sub-Saharan Africa and elsewhere.

Incidence of Haemonchus spp. and effect on haematocrit and eye colour in goats farmed under resource-poor conditions in South Africa

The diversity and predominance of nematode genera in goats of resource-poor farmers at Rust de Winter, Gauteng Province, Impendle, KwaZulu-Natal Province, and Kraaipan, North-West Province, South Africa, was determined by means of a longitudinal study of the nematode faecal egg counts (FECs) and differential third-stage nematode larvae. The animals were bled for haematocrit determination and scored for pallor of ocular mucous membranes using the FAMACHA( Copyright) method, an assay for clinical evaluation of anaemia caused by Haemonchus spp. Animals considered to be in danger of dying from anaemia caused by haemonchosis were selectively treated with an anthelmintic. Lower haematocrit values were registered during periods of heavier Haemonchus infection, which occurred from December/January to March for Rust de Winter; from December to March/April for Impendle; and from November/December to February or April for Kraaipan. There was agreement too between the lower haematocrits and paler mucous membranes scored according to the FAMACHA( Copyright) method. The use of this system may be recommended as part of an integrated approach to worm control in goats kept in the resource-poor areas studied.

Tactical treatment with copper oxide wire particles and symptomatic levamisole treatment using the FAMACHA© system in indigenous goats in South Africa

Haemonchosis is considered to be the most economically important gastrointestinal disease of small ruminants in the tropics and subtropics. However, chemical anthelmintics, which were the mainstay of control, have been compromised by a high prevalence of resistance worldwide. Copper oxide wire particles (COWP) have been shown to have anthelmintic effects, but few studies have examined their use under field conditions. The use of COWP was therefore evaluated as a tactical anthelmintic treatment in indigenous goats raised under communal farming conditions in Bergville, KwaZulu-Natal Province, South Africa. At the beginning of the summer rainfall season (October 2007), the faecal egg counts of 172 female goats belonging to 15 farmers were determined and this sampling continued every four weeks until the second week of January 2008. The goats within each of the 15 herds were ranked according to their faecal egg counts for this week. The goats were sequentially paired off within each ranking starting with those goats with the highest counts. One goat from each pair was randomly allocated to a treated or control group. Two weeks later, a 4 g COWP bolus was randomly administered to each goat in the treated group. Faecal egg counts were carried out on the goats two weeks following treatment, and the sampling of the goats then proceeded every four weeks until October 2008. Except for the six-week period prior to the administration of the COWP, the goats were examined according to the FAMACHA© system and symptomatically treated with 12 mg/kg levamisole when anaemic. The percentage reduction in faecal egg count due to the COWP treatment was 89.0%. Mean pre- and post-treatment faecal egg counts for the COWP-treated group (n = 73) were 2347 eggs per gram of faeces (epg) and 264 epg, respectively. The corresponding values for the untreated controls (n = 66) were 2652 epg and 2709 epg. The prevalence of Haemonchus spp. larvae in pre- and post-treatment faecal cultures was 72% and 46%, respectively. Symptomatic anthelmintic treatments in combination with mid-summer tactical treatments with COWP appear to be useful strategies for the control of Haemonchus contortus in indigenous goats in this farming system and this approach could have application in other similar agro-ecological zones.

Effect of nematode burden as assessed by means of faecal egg counts on body condition in goats farmed under resource-poor conditions in South Africa.

A longitudinal study was conducted of the nematode faecal egg counts (FECs) and body condition scores (BCSs) of goats of resource-poor farmers at Rust de Winter, Gauteng Province, Impendle, KwaZulu-Natal Province, and Kraaipan, North-West Province, South Africa. Periods of higher FECs occurred from December/January to March/April at Rust de Winter and at Impendle and from January to March at Kraaipan. Seasonal variations in body condition were evident in the goats at Impendle with the animals showing lower BCSs from June to October. The goats at Rust de Winter and at Kraaipan did not show clear seasonal variations, although the goats at Rust de Winter showed lower BCSs from mid-July to early December. The BCSs for Rust de Winter where the animals were grazed on a private farm were generally higher than those of the other sites, where communal grazing is practised.