The aims of the study were to determine the seroprevalence and incidence of human brucellosis in Arusha
and Manyara regions, risk factors for human brucellosis, health-seeking behavior and clinical features of
human brucellosis cases and to evaluate different diagnostic tests for brucellosis. Other objectives included
determination of the knowledge of medical practitioners relevant for diagnosis of zoonoses and estimation of
the burden of disease caused by human brucellosis in Tanzania.
From cross-sectional studies, the Brucella seroprevalence in humans was 4.8% when determined by assays
in the field and 6.4 % at the Sokoine University of Agriculture (SUA) based on the Rose Bengal Plate Test
(RBPT). Based on the competitive ELISA (c-ELISA) test conducted at the Veterinary Laboratory Agencies
(VLA) the seroprevalence of brucellosis was 7.7%. The majority of RBPT positive individuals were
asymptomatic. Most of the c-ELISA positive individuals were above 15 years of age with the age group
16-30 years having the highest number of seropositive individuals. There was a significant association
between the seroprevalence of brucellosis in humans and the seroprevalence of brucellosis in goats at the
Prospective hospital studies indicated that the incidence of brucellosis was 11.2 cases/100,000 people per
annum. Joint pain, headache, backache, fever and fatigue were the main clinical features described by the
confirmed (c-ELISA positive) patients, but these were also most commonly reported by the c-ELISA
negative patients initially suspected as having brucellosis. Patients with brucellosis delayed going to hospital
with a median delay time of 90 days. Distance to the hospital, keeping animals and knowledge of brucellosis
were significantly associated with patient delay to present to hospital. More cases of brucellosis were
recorded in hospitals located in pastoral areas and brucellosis was more common among people engaging in
Brucellosis was associated with assisting an aborting animal. It was shown that the closer the distance
between households, the higher the risk of brucellosis. People who were of Christian religion were found to
have a higher risk of disease compared to other religions.
The sensitivity and specificity of the RBPT in the cross-sectional survey were 39.4% and 98.8%
respectively, at the SUA laboratory 38.7% and 96.8% respectively and at the hospitals 44.3% and 89.5%
respectively. The sensitivities and specificities of the diagnostic tests for brucellosis at the hospitals were
also low. There was a poor agreement between the RBPT performed at SUA, the RBPT performed in crosssectional survey and the tests performed at the hospitals.
Medical practitioners in rural hospitals had poorer knowledge of most zoonoses when compared to the
practitioners in urban hospitals, including transmission of sleeping sickness, clinical presentations of anthrax
and rabies in humans. In both areas practitioners had poor knowledge of echinococcosis transmission to
humans, clinical features of echinococcosis in humans, and diagnosis of bovine tuberculosis in humans.
Brucellosis contributed to an estimated 3,644 -3,708 Disability Adjusted Life Years (DALY) burden in
Tanzania based on data collected from hospitals while data from the community resulted in an estimated
92,080 - 121,550 DALY burden in Tanzania. The majority of cases continued to have brucellosis clinical
features for a period of over two years, and out of these, five days spent as inpatients. Households used a
mean total of US $ 90.65 (92, 826 TShs.) to care for a single case of brucellosis per year and each health
provider used a mean total of US $ 858 (878,592 TShs.) per year to care for cases of brucellosis.
Brucellosis contributes to poverty and suffering particularly to the poor in the rural areas of Tanzania and yet
it is neglected. There is a need for increased health education on risk factors for transmission of brucellosis
to humans and the importance of going to hospital at an early stage of the disease. More efforts also need to
be directed towards improving the diagnosis and treatment of brucellosis to reduce prolonged human
suffering from brucellosis. This should include the adoption of standardized diagnostic and treatment
protocols. Restructuring and updating of disease recording systems and diagnostic laboratories so that they
diagnose and hence capture zoonoses such as brucellosis should be implemented. Efforts should be made to
equip practitioners with adequate knowledge relevant for identification of zoonoses.