Abstract:

In Uganda, anthelmintics are widely used in the control of gastrointestinal nematode (GIN)
parasites. However, control is not based on knowledge of the parasite epidemiology and status of
Anthelmintic efficacies. This has led to their indiscriminate use and spreading of resistant
nematodes in the ecosystem. This study hence identified the common GIN parasites, risk factors
to anthelmintic resistance and evaluated the efficacies of albendazole (Alb), Levamisole (Lev)
and Ivermectin (Tver) against natural GIN infections in goats in Gomba district. Fecal samples
were collected on day 0 (N=470) before treatment. Parasite eggs were identified using the
floatation technique, while worm burden (epg) were determined using the McMaster technique.
Fecal samples were pooled and cultured for 7 days at 27° C. L3 were extracted using Bearmann’s
technique and were identified using their morphological features. Goats with epg counts >
200epg were randomly set into 4 treatment groups: Alb, Lev, Iver and controls/placebo (n= 93).
Fecal samples were collected on days 7, 14 and 21 post-treatment and fecal egg count reduction
(FECR) test used to determine the efficacy for each treatment group. Risk factors for
anthelmintic resistance were identified using questionnaire interviews on 62 farms (15- 300)
goats/farm. Results: overall prevalence of GIN was 43%. Common GIN parasites were
Flaemonchus (56%), Oesophagostomum (33%) and Stronyloides (11%). Drug efficacies were;
Alb: (82, 80 and 61) % at days 7, 14 and 21, Lev: (95, 91 and 69) % and Iver: (85, 84 and 81) %
on the same days post treatment, respectively. Mean efficacies were; Lev (85%), Iver (83%) and
Alb (77.3%). Only Haemonchus were recovered in copro-cultures in Alb treated goats at day 21.
Major risk factors for reduced efficacy were; prolonged use of one drug type (97% Alb), weight
determination by visual appraisal (94%), self medication (67%) and grazing animals on
communal pastures (80%). In conclusion, level of GIN infections in goats in Gomba was low
probably due to heavy anthelmintic application. Haemonchus was the predominant GIN parasite.
Albendazole, levamisole and ivermectin were still effective against common GIN parasites in
Gomba but, (<90% efficacies) post-treatments was suggestive of possible parasite resistance
against these drugs. Prolonged use of one anthelmintic and visual estimation of animal weight
during treatment were the major risk factors for anthelmintic resistance. Specific reasons for the
low GIN parasite prevalence needed further investigation. Farmer education was recommended
to ensure judicious use of these drugs so as to maintain their current efficacies while alternative
approaches to complement chemotherapy are sought.