Risk Factors For Seropositivity Research Articles

A seroepidemiological survey of Mycobacterium avium subsp. paratuberculosis in sheep from North of Portugal

The aim of this study was evaluate the risk factors for Mycobacterium avium subsp. paratuberculosis (Map) seroprevalence in sheep in the North of Portugal. The effects on seroprevalence of several variables such as individual characteristics, management practices, farm characteristics, animal health, and available veterinary services were evaluated. This information was then used in a multivariable logistic regression model in order to identify risk factors for Map seropositivity. Univariable analysis was used to screen the variables used in the logistic regression model. Variables that showed p values of <0.15 were retained for the multivariable analysis. Fifteen variables were associated with paratuberculosis in univariable analysis. The multivariable logistic regression model identified a number of variables as risk factors for seropositivity like sheep pure local and/or a cross of a local breed (OR=2.02), herd size with 31-60 head (OR=2.14), culling during the Spring-Summer season (OR=1.69) and the use of an anti-parasitic treatment such as Ivermectin as the only anti-parasitic medication (OR=5.60). Potential risk factors identified in this study support current recommendations for the control of paratuberculosis.

Risk factors for seropositivity to bovine coronavirus and bovine respiratory syncytial virus in dairy herds

A cross-sectional study was conducted to evaluate the association between herd-level characteristics, management routines and farm-level antibody status of bovine coronavirus (BCV) and bovine respiratory syncytial virus (BRSV) in 257...

Emergence of Sylvatic Echinococcus granulosus as a Parasitic Zoonosis of Public Health Concern in an Indigenous Community in Canada

Within a remote Canadian Indigenous community, at least 11* of people had antibodies against Echinococcus granulosus and E. granulosus eggs were detected in 6* of environmentally collected canine fecal samples. Dog ownership, hunting, and trapping were not risk factors for seropositivity, suggesting that people are most likely exposed to E. granulosus through indirect contact with dog feces in the environment. In this situation, human exposure could be most effectively curtailed by preventing consumption of cervid viscera by free-roaming dogs.

Trichinella infection in a hunting community in East Greenland

Trichinella nativa infection (trichinellosis) is highly prevalent in Arctic wildlife, but the human burden of trichinellosis in present-day Greenland is unknown. The study aimed to determine Trichinella seroprevalence in an eastern Greenlandic hunting community and to evaluate risk factors for seropositivity. Overall, 998 inhabitants aged 10 years in the Ammassalik municipality were tested for Trichinella-specific IgG antibodies. Background information was obtained from questionnaires. Seropositivity was 1.4% in persons aged <40 years and increased to >12% in those aged 60 years. Older age, occupation as hunter or fisherman, and consumption of polar bear meat significantly increased the risk of Trichinella seropositivity. The seropositivity age pattern probably reflects changes in dietary preferences, but could also reflect mandatory meat inspection since 1966. However, preventive measures against Trichinella infection should be strengthened in Greenland.

High prevalence of both humoral and cellular immunity to Zaire ebolavirus among rural populations in Gabon.

To better understand Zaire ebolavirus (ZEBOV) circulation and transmission to humans, we conducted a large serological survey of rural populations in Gabon, a country characterized by both epidemic and non epidemic regions. The survey lasted three years and covered 4,349 individuals from 220 randomly selected villages, representing 10.7% of all villages in Gabon. Using a sensitive and specific ELISA method, we found a ZEBOV-specific IgG seroprevalence of 15.3% overall, the highest ever reported. The seroprevalence rate was significantly higher in forested areas (19.4%) than in other ecosystems, namely grassland (12.4%), savannah (10.5%), and lakeland (2.7%). No other risk factors for seropositivity were found. The specificity of anti-ZEBOV IgG was confirmed by Western blot in 138 individuals, and CD8 T cells from seven IgG+ individuals were shown to produce IFN-γ after ZEBOV stimulation. Together, these findings show that a large fraction of the human population living in forested areas of Gabon has both humoral and cellular immunity to ZEBOV. In the absence of identified risk factors, the high prevalence of “immune” persons suggests a common source of human exposure such as fruits contaminated by bat saliva. These findings provide significant new insights into ZEBOV circulation and human exposure, and raise important questions as to the human pathogenicity of ZEBOV and the existence of natural protective immunization.

Seroprevalence and risk factors for dengue infection in socio-economically distinct areas of Recife, Brazil

Brazil currently accounts for the majority of dengue cases reported in the Americas, with co-circulation of DENV 1-3. Striking variation in the epidemiological pattern of infection within cities has been observed. Therefore, investigation of dengue transmission in small areas is important to formulate control strategies. A population-based household survey was performed in three diverse socio-economic and environmental areas of Recife, a large urban center of Brazil, between 2005 and 2006. Dengue serostatus and individual- and household-level risk factors for infection were collected in residents aged between 5 and 64 years. A total of 2833 individuals were examined, and their residences were geo-referenced. Anti-dengue IgG antibodies were measured using commercial ELISA. The dengue seroprevalence and the force of infection were estimated in each area. Individual and household variables associated with seropositivity were assessed by multilevel models for each area. A spatial analysis was conducted to identify risk gradients of dengue seropositivity using Generalized Additive Models (GAM). The dengue seroprevalence was 91.1%, 87.4% 74.3%, respectively, in the deprived, intermediate and high socio-economic areas, inversely related to their socio-economic status. In the deprived area, 59% of children had already been exposed to dengue virus by the age of 5 years and the estimated force of infection was three times higher than that in the privileged area. The risk of infection increased with age in the three areas. Not commuting away from the area was a risk factor for seropositivity in the deprived area (OR=2.26; 95% CI: 1.18-4.30). Number of persons per room was a risk factor for seropositivity in the intermediate (OR=3.00; 95% CI: 3.21-7.37) and privileged areas (OR=1.81; 95% CI: 1.07-3.04). Living in a house, as opposed to an apartment, was a risk factor for seropositivity in the privileged area (OR=3.62; 95% CI: 2.43-5.41). The main difference between the privileged and other areas could be attributed to the much larger proportion of apartment dwellers. Intensive vector control, surveillance and community education should be considered in deprived urban areas where a high proportion of children are infected by an early age.

Seroprevalence of Toxoplasma gondii Among Nunavik Inuit (Canada)

As a result of their intimate contact with the land and their nutritional habits, the Inuit of Nunavik are considered to be at risk from zoonotic infections. To better understand the risk factors for Toxoplasma gondii infection, a serosurvey was conducted in Nunavik, Québec, in September 2004. A representative sample of the Inuit adult population of Nunavik participated in this cross-sectional study (n = 917). Antibodies (IgG) against T. gondii were detected by immunoassay. Information on sociodemographic characteristics, traditional activities, domestic environment and nutrition was gathered by questionnaire and explored as variables explanatory of seropositive results. Associations found to be statistically significant in univariate analyses were assessed by multivariable logistic regression to control for confounding factors. Almost two thirds (59.8%) of the Inuit of Nunavik were found to be seropositive for T. gondii. In multivariate analyses, risk factors for seropositivity were: increasing age, gender (women > men), lower level of education, consumption of potentially contaminated water (determined by an index of risk from waterborne infections), frequent cleaning of water reservoirs, and consumption of seal meat and feathered game. There was some variation in seroprevalence between the Ungava Bay coast (52.3%) and the Hudson Bay coast (65.6%), the two main regions of Nunavik, but this variation was not significant in the multivariable logistic regression model. This cross-sectional study demonstrated high T. gondii seroprevalence in the Inuit population and revealed that age, gender, schooling and community of residence all influence serostatus in this population. Variables related to drinking water and food choices may also influence the risk of infection. These results raise important questions about T. gondii transmission in Nunavik including possible links between terrestrial and marine cycles.

Prevalence of and risk factors for serum antibodies against Leptospira serovars in US veterinarians

To determine the seroprevalence of antibodies against Leptospira serovars among veterinarians and identify risk factors for seropositivity in veterinary care settings. Seroepidemiologic survey. Veterinarians attending the 2006 AVMA Annual Convention. Blood samples were collected from 511 veterinarians, and serum was harvested for a microcapsule agglutination test (MAT) to detect antibodies against 6 serovars of Leptospira. Aggregate data analysis was performed to determine the ratio of the odds of a given exposure (eg, types of animals treated or biosafety practices) in seropositive individuals to the odds in seronegative individuals. Evidence of previous leptospiral infection was detected in 2.5% of veterinarians. Most veterinarians reported multiple potential exposures to Leptospira spp and other pathogens in the previous 12 months, including unintentional needlestick injuries (379/511 [74.2%]), animal bites (345/511 [67.5%]), and animal scratches (451/511 [88.3%]). Treatment of a dog with an influenza-like illness within the past year was associated with seropositivity for antibodies against Leptospira spp. Veterinarians are at risk for leptospirosis and should take measures to decrease potential exposure to infectious agents in general. Diagnostic tests for leptospirosis should be considered when veterinarians have febrile illnesses of unknown origin.

Risk factors for toxoplasmosis in pigs bred in Sicily, Southern Italy

The aim of the study was to determine the seroprevalence of Toxoplasma gondii infection in pigs raised and slaughtered in Sicily, Southern Italy, and to evaluate the risk factors associated with the infection. Samples were collected in seven slaughterhouses and on-site on 274 raising farms across Sicily, in the period from January 2006 until March 2007. For each sampled pig born and raised in Sicily, information was obtained on gender, age, origin, final destination of meat and farm management. Data on the farm included: farming type, presence of cats and dogs, rodent control by rodenticides, cleaning methods, water supply, altitude and herd size. T. gondii-specific antibodies were detected using a commercial Enzyme-Linked Immunosorbent Assay (Institut Pourquier, France).Antibodies against T. gondii were found in 16.3% of Sicilian pigs. The lowest seroprevalence, 7%, was found in the age group 5–7 months (market pig) and the highest, 19%, in the age group >24 months. Risk factors for seropositivity were: age 11–24 months compared to younger (OR 5.62; CI 1.52–20.8); farrow-to-finish farming type (OR 6.85; CI 1.87–25.01) compared to finishing and farrow-to-breed type; less than 50 pigs on the farm (OR 6.8; CI 1.76–26.2); no use of rodenticides (OR 2.71; CI 1.10–6.64), use of water coming from private sources (especially wells; OR 2.8; CI 1.03–7.72).Pigs raised in Sicily shows a high prevalence of antibodies against T. gondii. Pre-harvesting interventions to lower the risk of locally produced meat consumption for consumers should point as soon as possible to increase hygienic condition on the farm, by carefully removing waste with automatic cleaning and reducing biohazard by rodent control. Consumers must receive information on the correct handling and cooking locally produced pork meat derivatives.

Risk factors for seropositivity to H5 avian influenza virus in ostrich farms in the Western Cape Province, South Africa

In a 2005 serological survey, carried out in response to an outbreak of H5N2 avian influenza (AI) in ostriches in the Eastern Cape Province, 16.3% of ostrich farms in the Western Cape Province of South Africa were found to be seropositive to H5 AI virus. We subsequently carried out a questionnaire-based census survey on all available registered Western Cape ostrich farms that still existed at the end of 2005 (367 farms, of which 82 were seropositive), in order to identify risk factors associated with farm-level seropositivity. A farm was classified as seropositive for H5 AI virus if one or more birds had tested positive (haemagglutination inhibition titre >1:16) in the 2005 survey, which had been designed to detect a minimum within-group seroprevalence of 10%. For each farm, risk factor information was collected using a questionnaire administered during a face-to-face interview with each farm owner or manager. Information was obtained on the ostrich population, movements of birds, environmental factors, management practices, and frequency of contact between ostriches and various wild bird species. Multiple logistic regression models were developed for the whole Western Cape Province and also for the two largest ostrich farming regions, “Klein Karoo” and “Southern Cape”. Seroprevalence differed between regions, being highest in the Klein Karoo (31.6%). In all three models, increased risk of farm-level H5 AI virus seropositivity was associated with increasing numbers of ostriches, excluding chicks, present on the farm. Increased risk of seropositivity was associated with reduced frequency of cleaning of feed troughs (<1×/week vs. >1×/week), both overall (odds ratio (OR) = 4.5; 95% confidence interval (CI): 1.5, 13.3) and in the Southern Cape (OR = 53.6; 95% CI: 3.3, 864), and with failure to clean and disinfect transport vehicles, both overall (OR = 2.3; 95% CI: 1.1, 4.8) and in the Klein Karoo (OR = 2.6; 95% CI: 1.1, 6.5). Increased risk of seropositivity was also associated with increasing frequency of contact of ostriches with certain wild bird species: overall with white storks ( Ciconia ciconia), in the Southern Cape with gulls ( Larus spp.), and in the Klein Karoo with Egyptian geese ( Alopochen aegyptiaca).

Familial and herd-level associations with paratuberculosis enzyme-linked immunosorbent assay status in beef cattle1

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.

Cyclical changes in seroprevalence of leptospirosis in California sea lions: endemic and epidemic disease in one host species?

BackgroundLeptospirosis is a zoonotic disease infecting a broad range of mammalian hosts, and is re-emerging globally. California sea lions (Zalophus californianus) have experienced recurrent outbreaks of leptospirosis since 1970, but it is unknown whether the pathogen persists in the sea lion population or is introduced repeatedly from external reservoirs.MethodsWe analyzed serum samples collected over an 11-year period from 1344 California sea lions that stranded alive on the California coast, using the microscopic agglutination test (MAT) for antibodies to Leptospira interrogans serovar Pomona. We evaluated seroprevalence among yearlings as a measure of incidence in the population, and characterized antibody persistence times based on temporal changes in the distribution of titer scores. We conducted multinomial logistic regression to determine individual risk factors for seropositivity with high and low titers.ResultsThe serosurvey revealed cyclical patterns in seroprevalence to L. interrogans serovar Pomona, with 4–5 year periodicity and peak seroprevalence above 50%. Seroprevalence in yearling sea lions was an accurate index of exposure among all age classses, and indicated on-going exposure to leptospires in non-outbreak years. Analysis of titer decay rates showed that some individuals probably maintain high titers for more than a year following exposure.ConclusionThis study presents results of an unprecedented long-term serosurveillance program in marine mammals. Our results suggest that leptospirosis is endemic in California sea lions, but also causes periodic epidemics of acute disease. The findings call into question the classical dichotomy between maintenance hosts of leptospirosis, which experience chronic but largely asymptomatic infections, and accidental hosts, which suffer acute illness or death as a result of disease spillover from reservoir species.

A case–control study of risk factors for brucellosis seropositivity in Portuguese small ruminants herds

A case–control study involving 255 small ruminants herds randomly selected was carried out in Portugal between January and December 2004, to identify risk factors associated with brucellosis seropositivity. To achieve this objective, two groups of herds selected according their prevalence status were compared: “cases” (farms with seroprevalence higher than 5%, n = 123) and “controls” (farms seronegatives, n = 132). A carefully structured questionnaire was used to collect data from each herd. A statistical analysis to compare “case” versus “control” herds was performed with the variables obtained from the questionnaire and the seroprevalence results. The effects on seroprevalence of several variables such as: individual characteristics; farm management practices; farm characteristics; animal health; knowledge and characteristics of farmers were evaluated. Data were analysed using logistic regression. Univariable analysis was used to screen the variables used in the logistic regression model. Nine variables were associated with brucellosis seropositivity in univariable analysis p < 0.10. These variables were retained for multivariable logistic regression model. Regression model identified five variables as risk factors for seropositivity. The odds of brucellosis were increased: herds with more than 116 animals (OR = 2.99); in herds with no cleaned-watering places (OR = 3.05); in herds with insufficient manure removal and insufficient cleaning of premises (OR = 2.87); in introduction of animals from non-free brucellosis herds or from herds of unknown status (OR = 12.11). In the other hand, farmers’ age (the eldest) was related to decreased odds (OR = 0.4). Potential risk factors identified in this study were consistent factors associated with brucellosis seropositivity and support current recommendations for the control of brucellosis. Considering the paucity of epidemiological reports on brucellosis in the Northeast of Portugal and the absence of any data concerning factors related to either the prevention or the spread of the disease, our results could make a useful contribution towards the prevention of small ruminants brucellosis in the area.

Cytomegalovirus as an occupational risk in daycare educators.

Cytomegalovirus (CMV) infection continues to be an important occupational risk in the daycare setting. A comprehensive update of scientific evidence is timely to inform and promote appropriate preventive measures. A review of the literature was conducted to examine the evidence for an occupational risk of CMV infection in daycare educators. Sources included Medline, government documents and additional references from published bibliographies. The key words used for searches were 'child day care centres' or 'nurseries' and 'cytomegalovirus' or 'cytomegalovirus infection'. EIGHT CMV SEROPREVALENCE STUDIES ON DAYCARE EDUCATORS IN INDUSTRIALIZED COUNTRIES WERE FOUND: four in the United States, three in Canada and one in Italy. Risk factors for seropositivity were older age, nonwhite race, foreign birth, birth in a low- or middle-income country, diaper changing, having children at home, and a child to educator ratio greater than 6:1 in children 18 to 35 months of age. Risk factors for seroconversion were younger age and working with young children. These studies suggest that daycare centres may be a high-risk setting for CMV infection. Recommendations to prevent CMV infection in this setting include handwashing, selective serological screening, avoiding work with younger children if pregnant and, in some cases, preventive leave from work. Evaluation and expert opinion of the effectiveness of various preventive options for CMV acquisition are needed to ensure that recommendations are evidence-based.

Seroepidemiology of canine babesiosis and ehrlichiosis in a hospital population

Canine ehrlichiosis and babesiosis have a worldwide distribution with geographic variation in prevalence and main clinical manifestations. We prospectively determined seroprevalence of canine babesiosis and ehrlichiosis, and risk factors for seropositivity. Three hundred and eighty-one dogs were randomly selected to represent the canine population at a Veterinary Teaching Hospital in south Brazil (latitude 23° S). Dogs were tested with a point-of-care ELISA for Ehrlichia canis antibodies and IFA to confirm previous exposure to Babesia vogeli. Multiple logistic regression analysis was then used to estimate adjusted odds ratio (OR) and their 95% confidence intervals. One hundred and thirty-six (36%) dogs were seropositive for B. vogeli antibodies, whereas 87 (23%) dogs were seropositive to E. canis antibodies. Fifty-four (14%) dogs seroreacted to both agents. Adult dogs previously infested with ticks were more likely to seroreact to B. vogeli or E. canis. Superficial bleeding (OR = 12.4) was more common in dogs exposed to B. vogeli, whereas neurological signs (OR = 7.7) were more common in dogs seropositive to E. canis. Neurological signs (OR = 12.0) and lameness (OR = 12.8) were more prevalent in dogs that seroreacted to both organisms. Owners of dogs with ticks were more likely to have been exposed to ticks themselves (OR = 3.2). Canine babesiosis and ehrlichiosis appear to be highly prevalent in this hospital population. Clinical signs differed from the most common signs in other regions with bleeding occurring more in dogs seropositive to babesiosis, but not ehrlichiosis; neurologic signs in dogs with E. canis antibodies; and lameness in dogs that seroreacted to both organisms.

Seroprevalence of feline leukemia virus and feline immunodeficiency virus infection among cats in North America and risk factors for seropositivity

To determine seroprevalence of FeLV and FIV infection among cats in North America and risk factors for seropositivity. Prospective cross-sectional survey. 18,038 cats tested at 345 veterinary clinics (n=9,970) and 145 animal shelters (8,068) between August and November 2004. Cats were tested with a point-of-care ELISA for FeLV antigen and FIV antibody. A multivariable random effects logistic regression model was used to identify risk factors significantly associated with seropositivity while accounting for clinic-to-clinic (or shelter) variability. 409 (2.3%) cats were seropositive for FeLV antigen, and 446 (2.5%) cats were seropositive for FIV antibody; 58 (0.3%) cats were seropositive for infection with both viruses. Multivariable analysis indicated that age, sex, health status, and cat lifestyle and source were significantly associated with risk of seropositivity, with adults more likely to be seropositive than juveniles (adjusted odds ratios [ORs], 2.5 and 2.05 for FeLV and FIV seropositivity, respectively), sexually intact adult males more likely to be seropositive than sexually intact adult females (adjusted ORs, 2.4 and 4.66), and outdoor cats that were sick at the time of testing more likely to be seropositive than healthy indoor cats (adjusted ORs, 8.89 and 11.3). Results suggest that certain characteristics, such as age, sex, health status, and lifestyle, are associated with risk of FeLV and FIV seropositivity among cats in North America. However, cats in all categories were found to be at risk for infection, and current guidelines to test all cats at the time of acquisition and again during illness should be followed.

Human-to-human transmission of avian influenza A/H7N7, The Netherlands, 2003

An outbreak of highly pathogenic avian influenza A virus subtype H7N7 began in poultry farms in the Netherlands in 2003. Virus infection was detected by RT-PCR in 86 poultry workers and three household contacts of PCR-positive poultry workers, mainly associated with conjunctivitis. To determine the magnitude of and risk factors for human-to-human transmission of influenza A/H7N7 in the Netherlands, a retrospective cohort study among household members of infected poultry workers was undertaken. In total, 33 (58.9%) of 56 (among 62) participants who provided blood samples had positive H7 serology, using single convalescent serum samples obtained at least 3 weeks after onset of symptoms of the index case. Eight household members (12.9%) reported symptoms (conjunctivitis and/or ILI), of which four of five (80.0%) tested seropositive. On univariate analysis, significant risk factors for seropositivity included having at least two toilets, a pet bird, and using cloth handkerchiefs. It was not possible to obtain a stable model for binomial regression for the outcome of A/H7N7 infection. Further seroprevalence studies among contacts of asymptomatic H7 cases should be conducted.

Seroprevalence of Q‐fever in febrile individuals in Mali

We conducted a serological survey for Q-fever among febrile patients in Bamako and Mopti (Mali) and investigated the main risk factors for seroconversion. Blood samples from 156 febrile patients were collected in healthcare facilities of Bamako and Mopti and examined with the microimmunofluorescence test. Forty per cent (n = 63) were seropositive for Q-fever, 28% in Bamako and 51% in Mopti. A more recent infection was suspected in 9.5% (n = 6) of all seropositive patients. This is the first time that Q-fever seropositivity is reported in febrile individuals in Mali. The patients' symptoms and diagnoses spanned a wide range of conditions; none had been diagnosed with Q fever by their treating physician. No risk factors for seropositivity could be identified with the exception of the city of residence and none could be identified with a logistic regression model with 'city' taken as random effect. A high rate of seropositivity to C. burnetii was found among febrile urban patients in Mali but no risk factors for seropositivity could be identified in this study.

Seroprevalence of antibodies against Bartonella species and evaluation of risk factors and clinical signs associated with seropositivity in dogs

To determine the seroprevalence of antibodies against Bartonella spp in a population of sick dogs from northern California and identify potential risk factors and clinical signs associated with seropositivity. Sera from 3,417 dogs. Via an ELISA, sera were analyzed for antibodies against Bartonella vinsonii subsp berkhoffii, Bartonella clarridgeiae, and Bartonella henselae; test results were used to classify dogs as seropositive (mean optical density value > or = 0.350 for B henselae or > or = 0.300 for B clarridgeiae or B vinsonii subsp berkhoffi) or seronegative. Overall, 305 dogs (102 seropositive and 203 seronegative dogs) were included in a matched case-control study. 102 of 3,417 (2.99%) dogs were seropositive for > or = 1 species of Bartonella. Of these, 36 (35.3%) had antibodies against B henselae only, 34 (33.3%) had antibodies against B clarridgeiae only, 2 (2.0%) had antibodies against B vinsonii subsp berkhoffii only, and 30 (29.4%) had antibodies against a combination of those antigens. Compared with seronegative dogs, seropositive dogs were more likely to be herding dogs and to be female, whereas toy dogs were less likely to be seropositive. Seropositive dogs were also more likely to be lame or have arthritis-related lameness, nasal discharge or epistaxis, or splenomegaly. Only a small percentage of dogs from which serum samples were obtained had antibodies against Bartonella spp. Breed appeared to be an important risk factor for seropositivity. Bartonella infection should be considered in dogs with clinical signs of lameness, arthritis-related lameness, nasal discharge or epistaxis, or splenomegaly.

Prevalence of and risk factors for paratuberculosis in purebred beef cattle

To estimate the prevalence of paratuberculosis in purebred beef cattle in Texas and identify risk factors for seropositivity. Epidemiologic survey. 4,579 purebred cattle from 115 beef ranches in Texas. Blood was collected, and serum was analyzed for antibodies with a commercial ELISA. Fecal samples were collected and frozen at -80 degrees C until results of the ELISA were obtained, and feces from seropositive cattle were submitted for mycobacterial culture. Herd owners completed a survey form on management factors. Results of the ELISA were positive for 137 of the 4,579 (3.0%) cattle, and 50 of the 115 (43.8%) herds had at least 1 seropositive animal. Results of mycobacterial culture were positive for 10 of the 137 (7.3%) seropositive cattle, and 9 of the 50 (18%) seropositive herds had at least 1 animal for which results of mycobacterial culture were positive. Risk factors for seropositivity included water source, use of dairy-type nurse cows, previous clinical signs of paratuberculosis, species of cattle (Bos taurus vs Bos indicus), and location. Results suggested that seroprevalence of paratuberculosis among purebred beef cattle in Texas may be greater than seroprevalence among beef cattle in the United States as a whole; however, this difference could be attributable to breed or regional differences in infection rates or interference by cross-reacting organisms. Veterinarians should be aware of risk factors for paratuberculosis as well as the possibility that unexpected serologic results may be found in some herds.