A DISSERTATION SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE IN EPIDEMIOLOGY OF THE SOKOINE UNIVERSITY OF AGRICULTURE. MOROGORO, TANZANIA.Emerging and re-emerging diseases in middle and low income countries particularly in agro-pastoral and pastoral communities pose major concern in animal and public health sectors which affect livelihoods and economy of communities. Improved surveillance system approaches could help to ensure prompt detection, reporting, recording and analyzing the incidence of diseases and response to outbreaks. A retrospective epidemiological study, was conducted to investigate common clinical signs and symptoms of diseases reported by Community Health Reporters (CHRs) in the pastoral and agro-pastoral communities in Ngorongoro district between December 2014 and May 2015, was carried out to identify most prevalent and determine trend of signs and symptoms in animals and human populations. Data collected by CHRs were retrieved from the Southern African Centre for Infectious Disease Surveillance (SACIDS) database, collated and analysed. Descriptive statistics including frequencies and proportions were computed. In addition, spatial analysis wascarried out to establish spatial distribution of clinical signs and symptoms. Cluster analysis was performed using space-time permutation modeling approach. A total of 10 study villages (in six wards) were studied, two villages out of 10 had high frequency of reported signs and symptoms in human of 65% and 25.5% respectively, with high frequency of reported signs and symptoms in female (56.6%) than males 43.4% (p=0.0057). In human, fever, coughing, headache, diarrhoea, joint pain, nausea and vomiting were reported more frequently than other clinical signs and symptoms in Malambo (65%) and Esere (25.4%). In animals, three villages namely Esere, Misigiyo and Alailelai recordedhigh frequency of reported signsof 34.0%, 21.2%, and 14.1%, respectively. There werethree identified statistically significant spatio-temporal clusters of clinical signs and symptoms in human and two in animals. Hence, use of CHRs is useful in capturing early signs and signals of diseases at community level. This system should be encouraged and strengthened particularly in remote areas where traditional surveillance could not promptly detect disease outbreaks.