Seroprevalence of Babesia bigemina in smallholder dairy cattle in Tanzania and associated risk factors

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.     

Seroprevalence estimation and management factors associated with high herd seropositivity for <Emphasis Type="Italic">Anaplasma marginale</Emphasis> in commercial dairy farms of Puerto Rico

A cross-sectional study was conducted to determine individual cow seroprevalence of Anaplasma marginale in adult lactating dairy cattle of Puerto Rico (PR) and to assess the associations of farm management factors on herd seroprevalence. Antibody activity against A. marginale was determined using the MSP-5 competitive enzyme-linked immunosorbent assay. Serum samples were obtained from 2,414 adult lactating dairy cattle from 76 randomly selected commercial dairy farms. Herd seroprevalence ranged from 3 to 100% with an overall individual cow seroprevalence for A. marginale of 27.4%. Factors associated with high herd seropositivity were pasture grazing as the main feed source (OR = 6.5, 95% CI = 1.2–34), observed monkeys on the premises (OR = 13, 95% CI = 1.2–138), use of 11% permethrin (OR = 17, 95% CI = 2.2–129), farmers who attended an acaricide certification program (OR = 0.18, 95% CI = 0.04–0.74), and lack of a fly control program (OR = 5.6, 95% CI = 1.3–24).     

Risk factors for smallholder dairy cattle mortality in 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.     

A comparison of seroprevalence and risk factors for Theileria parva and T. mutans in smallholder dairy cattle in the Tanga and Iringa regions of Tanzania

A cross sectional serological survey was carried out in two geographical small-scale dairying areas of Tanzania to determine the distribution and prevalence and to quantify risk factors for Theileria parva and T. mutans during the period January to April 1999. The prevalence of serum antibodies to these two Theileria parasites was determined using an indirect enzyme-linked immunosorbent assay (ELISA) technique. The results suggest that the parasites are widely distributed through out the two study sites and seroprevalence of 23% and 48% for T. parva were obtained for Tanga and Iringa regions, respectively. Seroprevalence of T. mutans ranged from 17% in the Tanga region to 40% in the Iringa region. Farm and animal data were collected and analysed by multiple logistic regression models to explore the risk factors associated with seroprevalence to T. parva and T. mutans pathogens. In both regions, seroprevalence for the two Theileria spp. pathogens increased significantly with age. Pasture grazed animals were more likely to be seropositive than those that were zero-grazed. Among individual animal characteristics, seropositivity was higher in cash-bought and charity gifted animals compared to cattle obtained using a formal credit agreement. Further studies on the relative role of risk factors for theileriosis found in this study may assist in the development of an effective control package.     

A Cross-sectional Study of Reproductive Performance of Smallholder Dairy Cows in Coastal Tanzania

A retrospective cross-sectional study was conducted on 200 randomly selected smallholder farms from a mixed dairy farming system in Tanga, Tanzania, between January and April 1999. We estimated the frequency and determinants of long calving interval (LCI), retention of fetal membrane (RFM), dystocia, and abortion in smallholder crossbred cattle and explored birth trends. The mean calving interval was 500 days and birth rate was 65 per 100 cow-years. Dystocia was reported to affect 58% of calvings, and 17.2% of animals suffered RFM. Using mixed effect models, the variables associated with LCI, RFM and dystocia were breed, level of exotic blood and condition score. Zebu breeding was associated with LCI (odds ratio (OR) = 2.3, p = 0.041) and Friesian breeding with lower odds for RF (OR = 0.26, p = 0.020). Animals with higher levels of exotic blood had lower odds for evidence of dystocia (OR = 0.45, p =0.021). Evidence of dystocia was significantly associated with poor condition score (P = −1.10, p = 0.001). Our observations suggest that LCIs are common in smallholder dairy farms in this region and a likely source of economic loss. Dystocia, RFM, poor condition score and mineral deficiency were common problems and were possibly linked to LCI.     

Management factors associated with Babesia bovis seroprevalence in cattle from eastern Yucatán, Mexico

The effect of management on the seroprevalence of Babesia bovis was studied in 399 Bos indicus cattle 1–2 years old from 92 farms in the eastern Yucatán, México. The management factors studied were: farm-type, production system, herd size, farm size, stocking density, vector control, dipping interval, type of dipping, type of acaricide and cattle introduction to the farm. A cross-sectional study was carried out (2-stage cluster sampling). The number of serum samples was proportionally distributed according to the number of farms in the nine locations of eastern Yucatán, México (399 animals from 92 farms). Antibody activity to B. bovis was tested using an indirect ELISA. The farms with a seroprevalence ≤75% were considered as cases and those with seroprevalence >75% were considered as controls. The variables with p ≤ 0.20 were included in fixed effects logistic regression. The seroprevalence of the zone was 73.8% (66.3–81.3%). The following risk factors were found: Stocking density (<1 head/ha, OR = 4.04, CI (OR) = 1.20–13.62) and dipping interval (>60 days, OR = 5.07 CI (OR) = 1.26–20.48).     

Survey of brucellosis at the wildlife–livestock interface on the Zimbabwean side of the Great Limpopo Transfrontier Conservation Area

A cross-sectional study was conducted to determine the seroprevalence of bovine brucellosis in communal cattle and wildlife at a wildlife–livestock interface in the southeast lowveld of Zimbabwe, part of the Great Limpopo Transfrontier Conservation Area. RBT and c-Elisa were used in serial for detection of antibodies against Brucella spp. Between July 2007 and October 2009, a total of 1,158 cattle were tested and the overall seroprevalence of brucellosis was 9.9%. A total of 97 wild animals (African buffaloes (n = 47), impala (n = 33), kudu (n = 16), and giraffe (n = 1)) were tested and only one animal (giraffe) was seropositive for brucellosis (1.03%). Brucella seroprevalence showed an increasing trend with age, with adult cattle (>6 years) recording the highest seroprevalence (11.1%), but the differences were not statistically significant. Similarly, female cattle recorded a relatively higher seroprevalence (10.8%) compared to males (7.9%), but the difference was not significant. However, a significant (P < 0.001) association between Brucella seropositivity and abortion history was recorded in female cattle. Similarly, Brucella seropositivity was significantly (P < 0.01) associated with a history of grazing in the park for female cattle. Overall, from the interface area, cattle with a history of grazing in the park recorded a significantly (P < 0.01) higher Brucella seroprevalence (13.5%) compared to those with no history of grazing in the park (4.9%). The significant association between abortion history and seropositivity observed in this study illustrates the potential economic significance of Brucella in cattle in this area. Hence, public awareness and further epidemiological studies of the disease in wildlife, livestock, and humans in the study area are of great importance.     

Familial and herd-level associations with paratuberculosis enzyme-linked immunosorbent assay status in beef cattle

A cross-sectional study was performed to determine the odds of having a positive paratuberculosis ELISA result if the dam was ELISA positive in Texas beef cattle, adjusted for individual and herd-level risk factors for seropositivity. Texas beef cattle (n = 2,621) were tested for paratuberculosis by using a commercial ELISA and microbiologic culture of feces for Mycobacterium avium subsp. paratuberculosis (MAP). Pedigree data were collected to identify dam-and sire-offspring pairs. Bayesian mixed-effects logistic regression was used to estimate the odds of seropositivity associated with age, dam ELISA status, sire ELISA status, herd size, herd history of clinical paratuberculosis, within-herd seroprevalence, within-herd fecal MAP prevalence, and within-herd fecal non-MAP Mycobacterium spp. prevalence. Herd of residence was included as a random effect to account for the correlation of observations within the same herd. Statistically probable associations were observed between ELISA status and herd fecal MAP prevalence [OR (odds ratio) 1.28 per 1% increase; P < 0.001] and herd seroprevalence (OR 1.21 per 1% increase; P < 0.001). The association with dam ELISA status was small (OR 1.35) and not highly probable (P = 0.69). Results indicate that use of dam ELISA status to make culling decisions in beef cattle may not improve the success of paratuberculosis control programs. Alternative strategies may be more effective for reducing the odds of seropositivity.     

Sero-epidemiological investigation of bovine toxoplasmosis in traditional and smallholder cattle production systems of Tanga Region,Tanzania

In view of the worldwide importance of Toxoplasma gondii and the fragmented information on the seroprevalence of the disease in animals in Tanzania, a study, using the modified Eiken latex agglutination test (LAT), was conducted from May 2003 to January 2004 to determine the prevalence of antibody to T. gondii in 130 randomly selected farms comprising 655 cattle. The overall seroprevalence of T.gondii antibodies in cattle and farms were 3.6% and 13%, respectively. Risk factors for animal and herd-level toxoplasmosis seropositivity were tested using multivariable logistic regression to control for confounding factors. Cattle managed under traditional husbandry practises were more likely to be seropositive than those managed under smallholder practises (48% versus 4.7%; p < 0.01). Herd size of ≥ 9 cattle were at greater risk of acquiring infection than herds holding fewer animals [≤ 9 cattle], (odd ratio [OR] = 3.99; 95% confidence interval [CI], 0.97–16.48; P = 0.001). We concluded that seroprevalence at herd level was high and relatively low at animal level, possibly due to the reduced susceptibility of cattle to T.gondii infection as compared to goats and sheep. The high seroprevalence in animals managed by traditional husbandry practise suggests that the parasite is widely distributed in the environment and could pose a public health threat to the people living in those areas.     

Seroprevalence estimation and management factors associated with high herd seropositivity for <Emphasis Type="Italic">Babesia bovis</Emphasis> in commercial dairy farms of Puerto Rico

A cross-sectional study was conducted to determine individual cow seroprevalence of Babesia bovis in adult lactating dairy cattle of Puerto Rico (PR), to assess the associations of farm management factors on herd seroprevalence, and to document the species of ticks infesting cattle within these farms. Antibody activity against B. bovis was determined using an indirect fluorescent antibody test (IFAT). Serum samples were obtained from 2,414 adult lactating dairy cattle from 76 randomly selected commercial dairy farms. Herd seroprevalence ranged from 0 to 51% with an overall individual cow seroprevalence for B. bovis of 26%. Ticks were collected from animals on 7 (9%) of the 76 participating commercial dairy farms. All collected ticks (n = 87) were Rhipicephalus (Boophilus) microplus. Factors associated with high herd seropositivity were dairy farms with calf but not heifer raising facilities (OR = 16, 95% CI = 3.0-86), having more than 4 neighbors with cattle (OR = 17, 95% CI = 1.6-178), same producer owning more than one farm (OR = 7.2, 95% CI = 1.6-32), and use of government services to apply amitraz on cattle (OR = 5.5, 95% CI = 1.5-20).     

Seroprevalence of <Emphasis Type="Italic">Anaplasma marginale</Emphasis> and <Emphasis Type="Italic">Babesia bigemina</Emphasis> infections and associated risk factors in Machakos County,Kenya

Anaplasma marginale and Babesia bigemina are important tick-borne pathogens of cattle. A cross-sectional survey was undertaken to determine the seroprevalence of A. marginale and B. bigemina infections and identify associated risk factors on traditional smallholder farms in Machakos County, Kenya. A total of 421 cattle from 127 farms from four divisions in the county were sampled and visited between September and November 2007. The farms were selected by a proportional allocation approach based on the number of farms in the four divisions previously selected by stratified random sampling method. Information on animal and individual farm management variables was obtained using standardized questionnaires. Prevalence of serum antibodies due to A. marginale and B. bigemina pathogens was determined using the enzyme-linked immunosorbent assay (ELISA) technique. The relationship between the seropositivity and associated risk factors was assessed by multivariable analyses using standard logistic regression models. The overall estimation (and their 95% confidence intervals) of A. marginale and B. bigemina seropositivity at the animal level was 53.4% (48.5%, 58.2%) and 40.6% (35.8%, 45.4%), respectively. Two variables, “animal age” and “administrative division,” were significantly associated with the A. marginale seroresponse. Three variables, “animal age” “grazing system” and “administrative division” were significantly associated with the B. bigemina seroresponse. These findings suggest possible indicators of existence of endemic instability for the two infections. The study identifies characterization of environmental suitability for the vectors and how they interact with grazing systems to cause the infections as an area for further studies, for improved understanding of the infections and in designing disease control programs.     

Seroprevalence of brucellosis and its associated risk factors in cattle from smallholder dairy farms in Zimbabwe

A cross-sectional study was conducted to investigate seroprevalence of brucellosis and the associated risk factors in cattle from smallholder dairy farms in Gokwe, Marirangwe, Mushagashe, Nharira, Rusitu and Wedza areas of Zimbabwe. A total of 1,440 cattle from 203 herds were tested serially for Brucella antibodies using Rose Bengal test and the competitive ELISA. Weighted seroprevalence estimates were calculated and risk factors in individual cattle investigated using logistic regression analysis. The overall individual animal brucellosis seroprevalence was low, with mean of 5.6% (95% confidence interval (CI), 4.4%, 6.8%). Gokwe had the highest individual (12.6%; 95% CI, 3.9%, 21.4%) and herd-level (40.0%; 95% CI, 22.1%, 58.0%), while Wedza had the lowest individual (2.3%; 95% CI, 0%, 5.3%) and herd-level (8.0%; 95% CI, 0.0%, 18.9%) brucellosis seroprevalence, respectively. In individual cattle, the area of origin, age and history of abortion were independently associated with brucellosis seroprevalence. While the seroprevalence was independent of sex, it decreased with increasing age. Cattle 2–4 years old had higher odds (odds ratio (OR) = 3.2; 95% CI, 1.1%, 9.1%) of being seropositive compared to those >7 years. Cows with a history of abortion were more likely to be seropositive (OR = 7.9; 95% CI, 3.1, 20.1) than controls. In conclusion, the area-to-area variation of brucellosis may be linked to ecological factors and differences in management practices. The implementation of stamping out policy, bleeding and testing animals before movement and promoting the use self-contained units are likely to significantly reduce the public health risks associated with Brucella infections in cattle.     

Seroprevalence and factors associated with bovine viral diarrhea virus (BVDV) infection in dairy cattle in three milksheds in Ethiopia

This work was conducted to estimate the seroprevalence, to identify potential factors that influence seroprevalence of bovine viral diarrhea virus (BVDV), and to investigate the association between BVDV serostatus and occurrence of reproductive disorders in dairy cattle in three milksheds in Ethiopia. A total of 1379 serum samples were obtained from cattle randomly selected from 149 herds from three milksheds representing central, southern, and western Ethiopia. Sera samples were examined for bovine viral diarrhea virus (BVDV) antibodies using commercial competitive enzyme-linked immunosorbent assay (ELISA) kit. Logistic regression analysis was employed to investigate associations between risk factors and the risk of BVDV seroprevalence, and BVDV serostatus and reproductive disorders. Seroreaction to BVDV antigens was detected in 32.6% of the 1379 cattle and 69.8% of the 149 herds sampled. Factors associated with BVDV seroplevalence were age, breed, and herd size (P?<?0.05). Adult cattle ≥?18 months old had 2.1 (95% CI 1.5, 3.1) times the odds of BVDV seroreaction than younger cattle. Holstein-Friesian (HF) local crosses (OR?=?2.1, 95% CI 1.3, 3.4) and HFs (OR?=?1.3, 95% CI 0.9, 1.9) were more likely to be seropositive than Jersey and the odds of seropositivity in cattle in large herds with 11 or more animals were higher (OR?=?1.8, 95% CI 1.3, 2.5) than the odds of BVDV seropositivity in smaller herds. Seroprevalence was not associated with geographical region (P?>?0.05). Risk of reproductive disorders was not affected by BVDV serostatus, except for repeat breeding (P?>?0.05). The present study demonstrated that BVDV has wide distribution in the country being detected in all the 15 conurbations and 69.8% of herds involved in the study.     

Prevalence of agglutinating antibodies to Toxoplasma gondii in small ruminants of the Madrid region,Spain, and identification of factors influencing seropositivity by multivariate analysis

A seroepidemiological survey of Toxoplasma gondii infection in sheep and goats was conducted in the Madrid region of Spain. Sera were collected from 60 herds, for which farming management information and other relevant data for their characterization were also obtained through a questionnaire. The seroprevalence was 11.8% (64 out of 541), using the modified (2-mercaptoethanol) direct agglutination technique with a 1:64 cut-off titre. The relationship between seropositivity and the variables in the questionnaire was assessed by multivariate analysis. Four variables were found to be significantly associated with seroprevalence. Two of them, the presence of cats and a previous history of abortion outbreaks in the farm, were factors known to be linked with toxoplasmosis, indicating the validity of the serological data. Seropositivity was also related to a lack of replacements in the preceding year. Proximity to other farms appeared to be a protective factor negatively associated with seropositivity, probably because it was an indicator of proximity to an urban area and the availability of local sanitary facilities.Abbreviations AIDS acquired immune deficiency syndrome - logistic regression coefficient - CI confidence interval - MDAT modified direct agglutination test - OR odds ratio - p level of significance - SE standard error     

Risk factors for tick attachment to smallholder dairy cattle in Tanzania

A cross-sectional study was conducted in Tanga and Iringa regions of Tanzania, and a longitudinal study in Tanga, to investigate tick-control methods and other factors influencing tick attachment to the cattle of smallholder dairy farms. Most farmers reported applying acaricides at intervals of 1-2 weeks, most used acaricides that require on-farm dilution and most farmers incorrectly diluted the acaricides. Rhipicephalus appendiculatus and Boophilus spp. ticks were those most-frequently encountered on the cattle, but few cattle carried ticks of any species (only 13 and 4.6% of tick counts of the cattle yielded adult R. appendiculatus and Boophilus spp., respectively). Animals were more likely to carry one or more adult Boophilus spp. ticks if they also carried one or more R. appendiculatus adults (OR=14.4, CI=9.2, 22.5). The use of pour-on acaricides was associated with lower odds that animals carried a R. appendiculatus tick (OR=0.29, CI=0.18, 0.49) but higher odds that they carried a Boophilus spp. tick (OR=2.48, CI=1.55, 3.97). Animals >4 months old and those with a recent history of grazing had higher odds of carrying either a R. appendiculatus (ORs=3.41 and 2.58, CIs=2.34, 4.98 and 1.80, 3.71), or a Boophilus spp. tick (ORs=5.70 and 2.18, CIs=2.34, 4.98 and 1.49. 3.25), but zero-grazing management did not prevent ticks attaching to cattle even when combined with high-frequency acaricide treatments. The odds that animals carried ticks varied amongst the agro-ecological zones (AEZs) and administrative districts where the farms were situated-but there was still considerable residual variation in tick infestation at the farm level.     

Seroprevalence of low pathogenic avian influenza (H9N2) and associated risk factors in the Gyeonggi-do of Korea during 2005-2006

Between November 2005 and March 2006, a total of 253 poultry flocks in the Gyeonggi-do of Korea were examined for seroprevalence against avian influenza (AI) using a hemagglutination inhibition (HI) test and an agar gel precipitation test. No low pathogenic avian influenza (LPAI) virus was isolated from 47 seropositive flocks that lacked clinical signs during sampling. The unadjusted percentage of seroprevalence rates of layer and broiler flocks were not significantly different, i.e., 26% (25/96) and 23% (22/97), respectively. The HI titer of the layers (mean = 89) was higher than the broilers (mean = 36; p < 0.001). A cross-sectional study was conducted for the seroprevalence of LPAI in the layers. Of 7 risk factors, farms employing one or more workers had a higher seropositive prevalence as compared to farms without hired employees (adjusted prevalence OR = 11.5, p = 0.031). Layer flocks older than 400 d had higher seropositivity than flocks younger than 300 d (OR = 4.9, p = 0.017). The farmers recognized at least one of the clinical signs in seropositive flocks, such as decreased egg production, respiratory syndromes, and increased mortality (OR = 2.3, p = 0.082). In a matched case-control study, 20 pairs of case and control flocks matched for type of flock, hired employees, age, and flock size were compared. Frequent cleansing with disinfectants was associated with a decreased risk of seropositivity (OR = 0.2, p = 0.022). Although there was a low statistical association, using a foot disinfectant when entering the building led to a decreased rate of seropositivity (OR = 0.3, p = 0.105).     

Correlations among <Emphasis Type="Italic">Anaplasma marginale</Emphasis> parasitemia and markers of oxidative stress in crossbred calves

The present study was designed to determine the correlations among Anaplasma marginale parasitemia and markers of oxidative stress in crossbred calves. Blood was collected from 11 crossbred calves infected with A. marginale along with 11 healthy crossbred calves as controls for determination of hematology and oxidative stress indicators. Percentage of parasitemia in infected calves varied from 0.8% to 6.0%. The values of hematological indicators and antioxidant enzymes were decreased, whereas erythrocytic lipid peroxidation (LPO) and plasma nitrate (NO) level were significantly (p < 0.05) augmented in A. marginale-infected animals over healthy group. Parasitemia was positively correlated (p < 0.01) with erythrocytic LPO and plasma NO and negatively correlated (p < 0.01) with hematological indicators and antioxidant enzymes. In addition, erythrocytic LPO was negatively correlated (p < 0.01) with the hemoglobin, erythrocyte count, and packed cell volume. From the present study, it can be concluded that anaplasmosis in crossbred calves is associated with a parasitic load-dependent oxidative damage as indicated by poor antioxidant status and enhanced oxidative stress, which are contributed to severe anemia.     

Seroprevalence and risk factors for bovine brucellosis in Jordan

We investigated the seroprevalence and risk factors for Brucella seropositivity in cattle in Jordan. The sera from 671 cows were randomly collected from 62 herds. The antibodies against Brucella were detected using a Rose Bengal plate test and indirect ELISA. A structured questionnaire was used to collect information on the cattle herds'' health and management. A multiple logistic regression model was constructed to identify the risk factors for Brucella seropositivity. The true prevalence of antibodies against Brucella in individual cows and cattle herds was 6.5% and 23%, respectively. The seroprevalence of brucellosis in cows older than 4 years of age was significantly higher than that in the younger cows. The seroprevalence of brucellosis in cows located in the Mafraq, Zarqa and Ma''an governorates was significantly higher than that of the other studied governorates. The multiple logistic regression model revealed that a larger herd size (odd ratio = 1.3; 95% CI: 1.1, 2.6) and mixed farming (OR = 2.0; 95% CI: 1.7, 3.7) were risk factors for cattle seropositivity to Brucella antigens. On the other hand, the use of disinfectants (OR = 1.9; 95% CI: 1.1, 2.1) and the presence of adequate veterinary services (OR = 1.6; 95% CI: 1.2, 3.2) were identified as protective factors.     

Associations between Campylobacter fetus, Haemophilus somnus, Leptospira hardjo and bovine viral diarrhea virus antibody titers in dairy cattle from a California herd

In a cross-sectional study, the associations of age, serological status against Campylobacter fetus (CF), Haemophilus somnus (HS) and Leptospira hardjo (LH) with the seroprevalence of bovine viral diarrhea virus (BVDV) in dairy cattle were evaluated. Six hundred and thirty cattle from a herd in Tulare county of California were included in the study. Blood samples from the cattle were collected in December 1986. Enzyme-linked immunosorbant assay (ELISA) was used to determine the positive or negative status of cows against CF, HS, LH and BVDV antigens. Loglinear analysis was used to describe the relationships of four categorical variables with the seroprevalence of BVDV. The final loglinear model was interpreted as a logit model and obtained by conditioning on explanatory variables in the model found to relate significantly with BVDV seropositivity. The hierarchical logit model included two two-way interactions (BVDV × HS and BVDV × LH) and a three-way interaction (BVDV × CF × age). HS-seronegative cattle had 4.7 times greater odds of being BVDV-seropositive compared with HS-seropositive cattle. In contrast, LH-seropositive cattle had 2.7 times increased odds of BVDV seropositivity compared with LH-seronegative cattle. The presence of the three-way interaction term in the model involving age, CF and BVDV seroprevalence implies that among heifers, CF-seronegative and CF-seropositive animals had about the same odds of BVDV seropositivity (e.g. adjusted odds ratios = 20.5 vs. 24.5), whereas, among cows, CF-seronegative animals had at least twice the odds of being BVDV-seropositive than those of CF-seropositive animals (e.g. adjusted odds ratios = 23.0 vs. 11.0).     

Herd- and animal-level risk factors for bovine leptospirosis in Tanga region of Tanzania

Leptospirosis is the zoonosis of worldwide distribution and common cause of economic loss and ill health among animals and human populations. A cross-sectional seroprevalence study, using a microscopic agglutination test (MAT) with a threshold titre of ≥1:160, to elucidate disease magnitude, distribution and associated risk factors in cattle in Tanga, Tanzania was conducted from May 2003 to January 2004. Serum (n = 655) samples collected from randomly selected herds (n = 130) were tested for antibodies against four different Leptospira interrogans serovars (Bataviae, Tarassovi, Hardjo and Pomona) used in the agglutination test. Positive titres were detected in 30.3% [95% confidence intervals (CI) = 26.7–33.9] of cattle and 58.5% (95% CI = 49.5–67.1) of herds, respectively. Of the 198 MAT positive serum samples, 98 (49.5%) were positive against serovar Hardjo, 80 (40.4%) were positive against serovar Tarassovi, 12 (6.1%) was positive against serovar Bataviae and eight (4%) were positive against serovar Pomona. Associations found to be statistically significant in univariate analyses (at P < 0.1) were assessed by multivariable logistic regression to control for confounding factors. The results showed that risk factors for cattle were pasture grazing [odd ratio (OR) = 2.83, 95% CI = 1.57–5.12, P = 0.001], presence of goats/sheep on the farm (OR = 1.73, 95% CI = 1.17–2.56, P = 0.001) and age of the animal (OR = 2.05, 95% CI = 1.42–2.96, P = 0.001), while concrete floor housing was protective (OR = 0.47, 95% CI = 0.30–0.74, P = 0.001). Herds managed under pasture grazing system were more likely to be sero-positive than those managed under zero grazed practices (OR = 9.31; 95% CI = 3.67–23.64 for grazing herd). We concluded that bovine leptospirosis is an endemic and locally widespread disease in Tanga and suggest that it may play a role in zoonotic transmission to humans.