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A study of infectious bursal disease (IBD) or 'Gumboro disease' seroprevalence rates in healthy, non-vaccinated indigenous scavenging chickens in northern Tanzania was conducted in November and December 2009 on 362 chickens raised in a traditional management system. Individual bird and flock-level information was collected using a semi-structured questionnaire, and serum samples were screened for IBD virus (IBDV) antibodies using the enzyme-linked immunosorbent assay (ELISA). The study revealed high rates of IBDV antibodies, yielding an overall seropositive rate of 58.8 % and with at least one positive bird detected in 82.8 % (74/90) of flocks. Univariate logistic regression analysis revealed that seropositivity to IBDV varied significantly (chi2 = 16.1, P < 0.001) between the study sites. The flock seroprevalence was found to vary from 37.5 % to 91 % between districts and from 75 % to 90 % between regions. The results of this study showed that IBD is an endemic and widely distributed disease in northern Tanzania.

A retrospective cross-sectional study of mortality was conducted on smallholder dairy farms in 2 separate regions (Iringa and Tanga) of Tanzania during the period of January to April 1999. A total of 1789 cattle from 400 randomly sampled smallholder dairy farms (200 each from Iringa and Tanga regions) were included in the study. These animals contributed a total risk period of 690.4 and 653.95 years for Tanga and Iringa, respectively. The overall mortality rates were estimated to be 8.5 and 14.2 per 100 cattle years risk for Tanga and Iringa regions, respectively; 57.7% of the reported deaths were of young stock less than 12 months old; 45% of reported young stock deaths (< or = 12 months old) were due to tickborne diseases, mainly East Coast Fever (ECF) and anaplasmosis. Disease events including ECF were reported to occur in all months of the year. Survival analysis using Cox proportional hazard models indicated that, in both regions, death rate and risk was higher in young stock less than 12 months than in older animals (relative risk RR = 4.92, P < 0.001 for Iringa; RR = 5.03 P = 0.005 for Tanga). In the Tanga region reported mortality rates were significantly higher for male animals (RR = 3.66, P = 0.001) and F2 compared with F1 animals (RR = 3.04, P = 0.003). In the Iringa region, reported mortality rates were lower for cattle on farms where the owner had attended a dairy development project training course (RR = 0.47, P = 0.012). Farms located in Iringa urban district and Pangani were associated with higher risk (mortality risk 21% for Iringa urban and 34% for Pangani). Our findings suggest that timely health and management interventions on these factors are necessary to alleviate losses from disease and emphasise that understanding variation in mortality risk within a population can enhance early response to potential outbreaks, reducing losses.

Serum samples collected in a cross-sectional survey of grazing cattle on Manyara Ranch, Monduli district, Tanzania, were tested by indirect major antigenic protein 1 fragment B (MAP 1-B) ELISA to determine the seroprevalence of Ehrlichia ruminantium and to assess ranch-level risk factors for heartwater. Heartwater-exposed cattle were widespread on the ranch and overall seroprevalence was 50.3% (95% CI, 44.9-55.6), enough to indicate an endemically unstable situation. Multivariate logistic regression modelling was used to identify risk factors associated with seropositivity. Two factors appeared to increase the herd's risk for contracting heartwater. Seroprevalence increased significantly with age (beta = 0.19 per year of age, P < 0.001) and animals carrying ticks of any species were associated with an increased risk of infection with E. ruminantium (Odds ratio, OR = 3.3, P < 0.001). The force of infection based on the age seroprevalence profile was estimated at 18 per 100 cattle year-risk. The current tick control measures on the ranch were associated with a decreased risk of infection with E. ruminantium (OR = 0.25 for no dipping and OR = 0.31 for low dipping, P < 0.001). Six tick species were identified; in order of frequency these were: Ambylomma variegatum 59.9%, Rhipicephalus evertsi evertsi 13.9%, Rhipicephalus pulchellus 12.5%, Hyalomma truncatum 7.03% and Rhipicephalus appendiculatus 6.07%. The least encountered tick was Rhipicephalus simus, which accounted for 0.38%. The cattle seemed well adapted to their environment and capable of resisting the tick burden under this extensive wildlife/livestock grazing and interaction system.

A case-control study was carried out to investigate a syndrome in smallholder dairy cattle in East Usambara Mountains characterised by urination of clotted blood. Smallholder dairy farms with the problem (cases) were matched with nearest farms without the problem (controls). In total, 30 farmers from Mbomole (19), Shebomeza (9) and Mlesa (2) villages in Amani division participated in the study. Using a structured questionnaire, information on risk factors associated with conditions characterised by passage of red urine in cattle was collected. In addition, serum samples from 80 smallholder dairy animals were collected and submitted for serodiagnosis of leptospirosis and babesiosis by microscopic agglutination test (MAT) and an indirect enzyme-linked immunosorbent assay (ELISA), respectively. Laboratory analysis showed that the seroprevalence of leptospirosis and babesiosis was 21.3% and 46.3%, respectively and there was no significant difference between'case' and 'control' farms (P > 0.05), hence the occurrence of urination of clotted blood syndrome in Amani was not explained. However, bracken fern (Pteridium aquilinum) was found to be ubiquitous in the area, and also found to be widespread in all areas used as sources of animal fodder Given the presence and distribution of bracken ferns and clinical signs and post-mortem lesions described by informants, chronic bracken-fern poisoning is more likely to be associated with the syndrome affecting animals in the study area. However, further investigation is required to confirm this observation so that appropriate control strategies can be devised.

Variations in the seroprevalence of antibody to Babesia bigemina infection by farm and animal level risk factors were investigated for 2 contrasting regions of Tanga and Iringa in Tanzania. Tanga is situated in the eastern part of the country and has typical tropical coast climate while Iringa is situated in the Southern Highlands and has a tropical highland climate. Two hundred farms from each region were selected using simple random sampling procedure and visited once between January 1999 and April 1999. Blood samples were collected from 1329 smallholder dairy animals on selected farms for harvesting serum which was subsequently used for serodiagnosis of B. bigemina using an indirect enzyme linked immuno-sorbent assay (ELISA). Of the 1329 sera samples screened, 34.9 % were positive for B. bigemina. The prevalence was higher in Iringa Region [43%, 95% confidence intervals (CI) = 39.5-47.3] than in Tanga Region (27%, CI = 23.6-30.5). Using a logistic binomial regression model as an analytical method for predicting the likelihood of animal seropositivity, we found (in both regions) that the risk of positive reaction varied with the animal's age, history of grazing and geographical location. Seroprevalence increased with age (beta = 0.01 and 0.01 per year of age, P < 0.005 in Tanga and Iringa, respectively). Animals located in Lushoto and Iringa urban district were associated with increased risk of seropositivity [Odds ratio (OR) = 4.24, P = 0.001, for Lushoto, and OR = 1.81, P = 0.040, for Iringa Urban, respectively). Animals grazed 3 months prior to sampling had higher odds for seropositivity than zero/semi-grazed, despite farmer-reported high frequency of tick control (OR = 2.71, P = 0.0087, for Tanga, and OR = 4.53, P = 0.001, for Iringa). Our study suggests that even though herd sizes are small, B. bigemina infection is widespread in many smallholder dairy farms and endemic stability with respect to this disease has not yet been attained, but the observed levels are sufficiently high to ensure that clinical disease would be a risk.

A survey to demonstrate the presence or absence of genital campylobacteriosis and trichomonosis in cross-bred breeding bulls kept under smallholding dairy farms in the Tanga region of Tanzania was carried out during the period of January-June 1996. Sheath washings, swabs and preputial scrapings were collected from 58 randomly selected bulls. Campylobacter fetus subsp. venerealis was demonstrated in 3/58 (5.1%) and Tritrichomonas foetus in 0/58 (0%) of all bulls tested. Bull-level variables of level of taurine genes (62.5% taurine genes, F2; 75% taurine genes, F3) and age were not significantly associated with campylobacteriosis (P > 0.05). The result of the study identifies Campylobacterfetus subsp. venerelias as the agent of enzootic infertility in smallholder herds and suggests that may be a significant problem.