A THESIS SUBMITTED IN FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF PHILOSOPHY OF THE SOKOINE UNIVERSITY OF AGRICULTURE; MOROGORO, TANZANIA. 2017A cross sectional study was carried out during the dry season (between June and August 2014) to establish the status of helminth infestation in nine traditionally managed small ruminant flocks in Mlandizi village of Melela ward in Mvomero district of the Morgoro region. A longitudinal study was thereafter implemented from August 2014 to January 2015 to determine the influence of Haemonchus spp. target Barbevax® vaccine on gastrointestinal parasite burdens in traditional sheep and goats using Barbevax® vaccine. Animals were visited after every 14 days for up to the 19th week. During each visit blood and faecal samples were collected. Vaccination was done four times on days 0, 28, 56 and 98. The vaccine was administered subcutaneously using 1 ml for each animal to be vaccinated. All the study flocks, which were communally grazed and purposively selected, had varying numbers of sheep and goats. The study involved 131 goats and 118 sheep, which were screened for helminth eggs and then the faecal samples, were cultured to recover helminth larvae (L3) which were identified using morphological features. Out of the animals screened, 54.2% and 67.8% of the goats and sheep examined respectively were positive for helminth infestation. The most prevalent helminth species detected was Haemonchus spp. (50.7%). Others were Trichostrongylus spp. (29%), Oesophagostomum spp. (16.4%), Cooperia spp. (5.9%) and Strongyloides spp. (3.4%). Results indicated that female sheep and goats had greater packed cell volume (PCV) than males with a significant difference (P< 0.05) and with ages 3, 6, 7 and 12 months (P< 0.05). At day 56 significant difference was observed between vaccinates and control animals (P< 0.05). The observation was that males had their EPGs going down gradually with a significant difference among males (P< 0.05). There was a significant difference in EPGs (P<0.05), for days 14 and 42. The mean EPG of males were relatively higher than those of females with a significant difference for both sexes (p<0.05). It was observed further that young animals (age 2-5 months) had relatively higher EPGs than older animals 6+ months. The mean number of larvae of Haemonchus between vaccinates and controls goats was statistically significant (p<0.05) for ages 3 and 9 months. No differences in either total or Haemonchus specific egg counts were observed between vaccinates and controls after third vaccination in either sheep or goats. Helminth infestation was shown to be a problem and haemochosis being the most prevalent. The potential of the vaccine efficacy in above associated risk factors is to be further studied in different environments under different infection rates of H.contortus. Futhermore, the studies to analyse plasma antibodies should be done to ascertain immune response after vaccination.