AHSI Final Report EXECUTIVE SUMMARY PROJECT FINAL REPORT

Transcription

1 AHSI Final Report Project #: Project Title: Project Lead: Determining the prevalence of Q Fever (Coxiella burnetii) in Ontario sheep flocks, goat herds and their farm workers Dr. Paula Menzies Collaborators: Dr. Andria Jones Bitton, Dr. Scott McEwen, Dr. Jocelyn Jansen (OMAFRA), Shannon Meadows (PhD candidate), Dr. Catherine Filjewski (MOH LTC), Dr. Samir Patel (PHO) Start date: May, 2010 End date: April, 2012 EXECUTIVE SUMMARY The objectives of the study were to determine the seroprevalence of Q Fever (Coxiella burnetii) in sheep flocks, goat herds and their farm workers in Ontario, and to examine the risk factors and protective measures that are associated with Q Fever exposure. The serology results from the 148 participating farms show that the farm level seroprevalence is 56.1% (83/148 farms having at least one animal test positive). At the individual animal level, the overall seroprevalence of Coxiella burnetii was 23.4% (1094/4525 animals testing serologically positive). In a logistic regression univariate analysis, the following animal covariates had a statistically significant association with the dichotomous farm level small ruminant serology status (p<0.05): the purchase of replacement animals from sales barns (p=0.03), the use of traps in the barn for rodent control (p=0.02), replacement animals having access to lambing or kidding areas after weaning (p=0.03), disposing of placentas in a manure pile (p<0.01), and the presence of other small ruminant farms within 5 km (p=0.04). Human results to date indicate that a high proportion of people (apparent individual level seroprevalence of 68.1%) and farms (apparent farm level human seroprevalence was 73.4%) are seropositive, suggesting that infection from Coxiella burnetii is common in people who care for sheep and goats in the province of Ontario. Based on these findings, it is very important to develop methods to protect people from this pathogen by controlling this infection on farms. PROJECT FINAL REPORT Objectives 1. To determine the sero prevalence of Coxiella burnetii infection in Ontario sheep flock and goat herds. 2. To determine the sero prevalence of Coxiella burnetii infection in farm workers on sheep and goat farms in Ontario. 3. To examine specific risk factors and outcomes of animal health and productivity in sheep and goat farms infected with Coxiella burnetii. Materials and Methods This cross sectional serological survey examined four defined small ruminant populations: dairy goat herds, meat goat herds (including hobby farms as well as commercial farms), meat sheep flocks and dairy sheep flocks. It comprised 2 major components: serological survey of breeding female animals onfarm to determine C. burnetii exposure status as well as a questionnaire to develop potential risk factors, protective measures, and productivity outcomes associated with animal exposure; and a serological survey of farm workers that have routine contact with the sheep or goats on that farm, as Page 1 of 8

2 well as a questionnaire to develop potential risk factors, protective measures and health outcomes associated with human exposure. Flocks and herds were selected randomly from databases of registered producers from their respective industry organizations. Some regions of north western Ontario with low populations of sheep and goats were excluded. To properly estimate a herd / flock prevalence of approximately 24% (with a 10% allowable error), the following numbers of herds were sampled: dairy goat 42; meat goat 35; meat sheep 49; dairy sheep 22, for a total of 148 herds and flocks. To detect a flock level seroprevalence of 10%, approximately 35 animals would need to be sampled per farm (10% allowable error). Blood samples were collected by the research team from female animals that have had at least 1 parturition within the previous 12 months, as these animals represent the highest risk of infection. The animal serum was tested for C. burnetii antibodies using the IDEXX ELISA kit, and was performed at the AHL in Guelph. All farm workers on selected farms who were 14 years of age and older were eligible for participation. Human blood samples were collected by a licensed phlebotomist either by visiting the farm or by having the participants visit a Human Diagnostic Laboratory. Human sera were tested for C. burnetii antibodies using the IFA (Focus Diagnostics) test which was conducted at Public Health Ontario (formerly the Ontario Agency of Health Protection and Promotion). A questionnaire investigating animal health and productivity factors was administered at the time of sampling. The following information was obtained: general herd demographics & sources of replacement stock; number of abortions including diagnoses if any; general herd health management, contact with other animal species (livestock, dogs, cats, rodents, wildlife etc.) and biosecurity practices. Every farm worker contributing a human blood completed a human health questionnaire. This questionnaire gathered information on farm worker demographics, undiagnosed illness in previous 12 months (e.g. fever, pneumonia, or other significant disease); contact with parturient animals (sheep, goats, other livestock, cats, dogs); consumption of raw milk on farm and other hypothesized risk factors. Data are being analyzed for plausible associations between C burnetii infection status (herd level) and farm level management practices. Additionally associations between evidence of human infection with C burnetii and risk factors are also being investigated. Results Personnel Employed in Whole or Part by the Project Shannon Meadows Start date: May 1, 2010 to Present. Initially an MSc candidate but after 3 semesters was moved to the PhD program. Shannon is expected to defend her thesis in the spring of Project management: Questionnaire development and testing, project applications (Human Ethics, Biohazard), ordering project supplies, drawing animal blood samples, processing whole blood, shipping serum for diagnostic testing, administering questionnaires, data entry and verification, model building, data analysis, and report composition. Helen Litchfield Start date: Sept End Date Dec Certified phlebotomist Arranged farm visits, collecting blood samples from humans who would like to participate in human serology, and shipping blood samples to Shannon Meadows for centrifugation. Benjamin Schlegel Start date: May 1, 2010, End date: Aug 30, Summer student Assisting project application: assisting with questionnaire development, drawing animal blood samples, & processing whole blood. David Baker Start date: May 1, 2010, End date: Aug 30, Summer student Assisting project application: assisting with questionnaire development, drawing animal blood samples, & processing whole blood. Page 2 of 8

3 Nina Gauthier Start date: May 2, 2011 End Date Aug Summer student Assisting project application: drawing blood samples, animal restraint, labeling samples & processing whole blood. Kelly Kozlowski Start date: May 2, 2011 End Date Aug Summer student Assisting project application: drawing blood samples, animal restraint, labeling blood samples & processing whole blood. Equipment purchases These were actually purchased by another AHSI project (299060) but were shared equally between projects Rotor set (Fisher Scientific) Bench top Centrifuge (Fisher Scientific) Whirlpool Top Mount Fridge (Shuh Appliances) Surveillance activities: Serology 4525 small ruminant blood samples have been collected from 148 farms from August 2010 to March An average of 30 animals per farm were sampled (SD=8.29), to a maximum of 35 animals per farm. A total of 167 human blood samples have been collected from 71 farms. The serology results from the 148 participating farms show that the farm level seroprevalence is 56.1% (83/148 farms having at least one animal test positive). The breakdown of the farm level seroprevalence by small ruminant sector is shown in Table 1. Table 1. Farm Level Animal Q Fever Serology Status in Ontario sheep flocks and goat herds by sector, September 2010 to February 2012 (n=148). Meat Sheep Meat Goats Dairy Sheep Dairy Goats Total Negative 29 (58.0%) 19 (55.9%) 8 (36.4%) 9 (21.4%) 65 (43.9%) Positive 21(42.0%) 15 (44.1%) 14 (63.6%) 33 (78.6%) 83 (56.1%) Total At the individual animal level, the overall seroprevalence of Coxiella burnetii was 23.4% (1094/4525 animals testing serologically positive). Table 2 describes the animal level seroprevalence in each small ruminant sector. Figures 1 and 2 also describe the proportions of goats and sheep, respectively, which were seropositive for Coxiella burnetii using the ELISA test. Table 2. Animal Level Serology Status in Ontario sheep flocks and goat herds by sector, September 2010 to November 2011 (n=4045). Meat Sheep Meat Goats Dairy Sheep Dairy Goats Total Negative 1420(89.5%) 667 (89.2%) 563 (75.7%) 814 (56.3%) 3464 (76.6%) Positive 166 (10.5%) 81 (10.8%) 181 (24.3%) 633 (43.7%) 1094 (23.4%) Total Human serological test results have been received from 113 samples from 53 farms and we are still waiting on some of the results. When complete, we expect about 100 farms to be represented in the dataset. Using the IFA, 36 of 113 samples were negative on both the Phase I and Phase II antibodies and the rest were positive on either one or both, for an apparent individual level seroprevalence of 68.1%. The apparent farm level human seroprevalence was 73.4% farms (39/54) with having at least one farm Page 3 of 8

4 worker test positive. Table 3 cross tabulates the farm level animal and human serological data for 36 farms for which both human and animal results. Table 3. Farm level animal and human serological data on Coxiella burnetii from 36 small ruminant farms in Ontario, Canada (September 2010 to November 2011) (n=36) Human Serology Animal serology Negative Positive Negative Positive Table 4 shows the distribution of Phase I and Phase II IgG antibody titres in the humans sampled in this project to date. The significance of this table is to determine the stage of infection. When disease is acute, Phase II titres are elevated and tend to be higher than Phase I. When chronic the reverse is usually the case but additionally Phase I titres tend to be high. Although elevated titres are not indicative of Q Fever, which must also include clinical evidence of disease either as signs or symptoms, there is concern when older or immunocompromised individuals have elevated Phase I titres. Table 4. Distribution of Phase I and Phase II antibody titres to Coxiella burnetii as determined by IFA in 113 humans from 53 farms. Phase I Antibody Titres < 1:16 1:16 1:32 1:64 1:128 1:256 TOTAL Phase II Antibody Titres < 1: : : : : : TOTAL Shaded areas represent Phase I titres greater than Phase II for that individual subject suggesting chronic Q Fever. However, most titres are sufficiently low that the chronic Q Fever cannot be determined with certainty. Those subjects whose Phase I titre is 1:256 should seek additional medical attention to be sure they are healthy. Analysis of risk factors will be completed once these samples have all be analyzed. Risk Factor Analysis In a logistic regression univariate analysis, the following animal covariates had a statistically significant association with the dichotomous farm level small ruminant serology status (p<0.05): the purchase of replacement animals from sales barns (p=0.03), the use of traps in the barn for rodent control (p=0.02), replacement animals having access to lambing or kidding areas after weaning (p=0.03), disposing of placentas in a manure pile (p<0.01), and the presence of other small ruminant farms within 5 km (p=0.04). Multiple logistic regression models will be constructed separately for sheep, goats and farm workers to examine potential risk and protective factors for C. burnetii seroprevalence. Discussion Prior to this study, a comprehensive serological examination of small ruminants had not been conducted in over 20 years. Additionally, there was a total absence of human serological prevalence data from Ontario in the scientific literature. This project addresses these knowledge gaps to determine the degree Page 4 of 8

5 of Q Fever exposure that is now present. In addition to providing information on the degree of exposure, this study also provides information about risk factors that were associated with positive farms, and protective measures associated with negative farms. This information can be used to guide future studies, and provide evidence for validating protocols designed to mitigate the future risk of Q Fever to small ruminants and their farm workers. The animal serological results indicate that exposure to C. burnetii is common on farms, as indicated by the farm level seroprevalence of 56.1% (83/148 farms), and an individual animal seroprevalence of 23.4% (1094/4525 small ruminants). Due to the representative nature of the study farms, we can also compare the relative seroprevalence in the four small ruminant sectors. Dairy goats had the highest seroprevalence on both the farm level and the animal level of all industry groups. The farm level seroprevalence on dairy goat farms was significantly higher than both meat sheep flocks (p =0.01) and meat goat herds (p=0.03). This information is useful for directing future control programs, as this evidence suggests dairy goats may represent a high risk of exposure among small ruminants in Ontario. The information gained from the risk factor analysis also provides much needed evidence to support control protocols and emergency preparedness practices in Ontario. Increasing the awareness of Q Fever risk factors like; purchasing replacement animals, allowing unrestricted animal access to birthing areas, and improper placental disposal can be done through educational campaigns directed at small ruminant producers and veterinarians to decrease the risk of exposure. The human samples are still be analyzed by Public Health Ontario and to date, results representing 53 farms are complete. Both the individual and farm level apparent seroprevalence indicate that infection in humans that work with small ruminants is common. This underlines the need to develop sound strategies to protect not only the animals but also the people that work with them. Emergency Preparedness Activities Biosecurity measures are important to control C burnetii infection, but we need to develop strategies to reduce the risk of infection, including shedding of the pathogen. While this study has examined only farm workers, it may be that service providers (veterinarians, shearers, DHI service providers) and people that live in the rural community with little animal contact may also be at risk. Vaccination is one route but access to an animal vaccine is expensive and difficult to obtain. Human vaccination is not possible at this time. Coxiella burnetii infection is proposed to be made an immediately notifiable disease in Ontario. This makes it even more important that we develop reasonable and effective strategies to control this infection. One of the researchers in this study (Dr. Paula Menzies) is taking part in the development of a consensus paper on management of C burnetii infection in farm livestock. This committee The Q Fever Working Group is an ad hoc committee formed at the request of the National Association of State Public Health Veterinarians. The document will be complete by early summer and will be made available to OMAFRA and the Ministry of Health and Long Term Care in order to help in developing a similar consensus paper. Page 5 of 8

6 FINAL BUDGET RECONCILIATION Year Item Salaries Salaries Equipment Equipment Supplies Supplies Other Other Total Total Graduate Student 20, Summer Student 8, Phlebotomist Travel to farms 15, Supplies 4, Serologic Testing 30, Graduate Student Summer Student Phlebotomist Travel to farms Equipment Supplies Serologic Testing Other Total 48,000 24, ,593 34,000 61,623 18,000 14, , ,355 Budget explanation: Originally we planned to use the AHSI to fund an MSc student but managed to secure other funds (MOHLTC and NSERC) for student salary. Originally we planned to have the graduate student perform the phlebotomy (human samples) but received a ruling from the Office of Research that only certified Health Care Professionals could do this task. So we hired a phlebotomist and later contracted with human laboratories to carry out the sampling. Travel to farms was offset by sharing this cost with another AHSI project (299060). Serological expenses are much greater than anticipated. As noted under communications, we have been very successful in having abstracts accepted at major international meetings for this work. We are slightly over but will transfer funds to Zero this account. Page 6 of 8

7 COMMUNICATIONS Completed Presentations and Publications as of April 20, 2012: Meadows, S., Menzies, P., Jones Bitton. A., Jansen, J., and McEwen, S. (2011). Seroprevalence and risk factors of Q Fever in small ruminants and farm workers in Ontario. OMAFRA Beef and Sheep Research Day, Guelph Ontario. (Institutional and Industry oral presentation for PhD work). Meadows, S., Menzies, P., Jones Bitton. A., Jansen, J., and McEwen, S. (2011). Seroprevalence and risk factors of Q Fever in small ruminants and farm workers in Ontario. Graduate Student Research Day, University of Guelph (Institutional poster presentation for PhD work). Meadows, S., Menzies, P., Jones Bitton. A., Jansen, J., and McEwen, S. (2011). Seroprevalence and risk factors of Q Fever in small ruminants and farm workers in Ontario. Canadian Animal Health Laboratories Network. Guelph Ontario. (National poster presentation for MSc work). Schaer, L. (2011).Crossover diseases Q Fever Study Impact: Diseases affecting both humans and animals are a unique challenge for farmers. Ontario Livestock Journal Magazine. Mar: 16 17, Menzies, P. Update on Q Fever. Grey Bruce Farmers Week. January 7, Elmwood, Ontario. Harvey, M. (2011). On farm Study targets Q Fever. University of Guelph Research Magazine. 1: 36. Meadows, S., Menzies, P., Jones Bitton. A., and Jansen, J. (2010). Q Fever: What Does it Mean for Ontario Goat Producers? International Goat Symposium (International oral presentation for MSc work). Meadows, S., Menzies, P., Jones Bitton. A., and Jansen, J. (2010). Seroprevalence and risk factors of Q Fever in small ruminants and farm workers in Ontario. Ontario Sheep Marketing Agency Annual General Meeting (Provincial poster presentation for MSc work). Meadows, S., Menzies, P., Jones Bitton. A., and Jansen, J. (2010). Q Fever: What small ruminant veterinarians need to know. Ontario Veterinary College Bovine Club (Institutional oral presentation for MSc work). Meadows, S., Menzies, P., Jones Bitton. A., and Jansen, J. (2010). Q Fever in Ontario Sheep. Ontario Sheep News Magazine. June edition: 15. (Provincial article for MSc work). Meadows, S., Menzies, P., Jones Bitton. A., and Jansen, J. (2010). Q Fever in Ontario Goats. Ontario Livestock Alliance Magazine. August edition: 28. (Provincial article for MSc work). communications Meadows, S., Menzies, P., Jones Bitton. A., Jansen, J., and McEwen, S. (2012). Determining the prevalence of Q Fever (Coxiella burnetii) in Ontario sheep flocks, goat herds and their farm workers. Global Development Symposium, Guelph Ontario. May 6 9, (Oral presentation at scientific conference, abstract accepted). Meadows, S., Menzies, P., Jones Bitton. A., Jansen, J., and McEwen, S. (2012). Determining the prevalence of Q Fever (Coxiella burnetii) in Ontario sheep flocks, goat herds and their farm workers. International Symposium for Veterinary Epidemiology and Economics, Maastricht, The Netherlands. August 20 24, 2012 (Poster presentation at scientific conference, abstract accepted). Menzies, P. Update on Q Fever. American Association of Small Ruminant Practitioners / American Association of Bovine Practitioners Meeting. September 20, Montreal, Canada. Meadows, S., Menzies, P., Jones Bitton. A., Jansen, J., and McEwen, S. (2012). Determining the prevalence of Q Fever (Coxiella burnetii) in Ontario sheep flocks, goat herds and their farm workers. AHSI Meeting, November Guelph, Ontario. Page 7 of 8

8 Meadows, S., Menzies, P., Jones Bitton. A., Jansen, J., and McEwen, S. (2012). Determining the prevalence of Q Fever (Coxiella burnetii) in Ontario sheep flocks, goat herds and their farm workers. Abstract submitted to the Internatinal Sheep Veterinary Congress, February 18 22, Rotorura New Zealand. As part of Shannon s PhD, we will be publishing several papers from her research. Shannon is expected to defend in late winter, Other Q Fever Activities Associated with the Project Summer students and research group developed Q fever fact sheets for producers and distributed them at producer meetings held in 2010 and Announcement of Funding by the Ministry of Health and Long Term Care. July, Liz Sandals MPP for Guelph held a press conference to announce funding of this important project. Menzies, P. Member of the Q Fever Working Group. Ad Hoc committee of the National Association of State Public Health Veterinarians (USA). This committee is developing national policy for the management of outbreaks and diagnoses of C. burnetii infection in livestock, and Q Fever in humans. Dr. Menzies is representing academia on the committee. This policy will be reviewed by OMAFRA and Ministry of Health and Long Term Care. Winter, Spring Menzies, P. Working the company that manufactures Coxevac (CEVA Sante Animale) to seek licensing and use of this vaccine within Canada. Met with Drs. Glen Gifford and Sheila Tan of the CFIA. April, Page 8 of 8