Epidemiology and control of Mycoplasma infections in swine

Transcription

1 Epidemiology and control of Mycoplasma infections in swine Maria Pieters, DVM, PhD Maria Pieters DVM, PhD Veterinary Population Medicine department and Veterinary Diagnostic Laboratory

2 Agenda Control Knowledge gaps Epidemiology Diagnostics Background information

3 Humans Plants Insects Animals: Food animals Companion animals Wildlife

4 Swine Mycoplasmas Pathogenic Non-pathogenic M. hyopneumoniae M. flocculare M. hyorhinis M. sualvi M. hyosynoviae M. hyopharyngis M. suis M. hyoarthrinosa M. hyogenitalium

5 Mycoplasma hyorhinis

6 Clinical disease Characterized by Fever (~) Decreased feed intake Depression Dyspnea Reluctance to move Swollen joints and lameness Growth retardation or death Occasionally Tilted head Abortions Conjunctivitis

7 Lesions Pleurisy Pericarditis Peritonitis Arthritis

8 Diagnostics Method/Test Clinical diagnosis Bacterial culture and isolation Genetic material detection (PCR) Antibody detection Antibiotic susceptibility Molecular characterization Feasibility/Notes Include H. parasuis, S. suis & M. hyosynoviae in differentials Doable Slow Only certain laboratories Rapid results High accuracy Not commercially available Rarely performed, as isolates are needed RFLP, MLST, MLVA among others

9 Diagnostics University of Minnesota - VDL

10 Diagnostics University of Minnesota - VDL

11 Genetic variability Dos Santos et al., 2015

12 Genetic variability Multiple-locus variable number tandem repeat analysis (MLVA) MLVA type Total Frequency Per sample type Tested material Sample type Geographical region Year of isolation/ sampling Isolate NA NA NA 1 Clinical specimen Pleura Midwest Clinical specimen and isolate Bronchial swab Midwest 2011, Isolate Bursa Midwest Isolate Joint Midwest Isolate NA NA NA 3 Isolate Pericardium Midwest Isolate Pleura Midwest 2011 Dos Santos et al., 2015

13 Epidemiology Most infections are subclinical Clinical disease presentation 3-10 woa Low level colonization in lactation Rapid spread early after weaning Incubation period 3-10 days Affected pigs fail to grow or die

14 Specific antibodies are observed 15 days post experimental infection Latex agglutination (Gois et al., 1972) Complement fixation (Ross et al., 1973) ELISA (Gomes Neto et al., 2014) (Gomes Neto et al., 2014)

15 M. hyorhinis detection in oral fluids and antibody response in wean-tofinish pigs (Gomes Neto, 2012) Prior to weaning M. hyorhinis detection: nasal swabs PCR (Clavijo, 2014)

16 Control Developing immunity No commercial vaccine available Autogenous vaccines in use Maternal immunity? Early exposure and immunity? Stopping the bacterium Antibiotic treatment Early intervention is key, especially for full recovery Mycoplasmas lack a cell wall Elimination?

17 Knowledge gaps Systemic dissemination drivers Antibody detection and interpretation Interpretation of molecular characterization Key aspects of effective disease control Involvement in other disease processes Involvement in human disease and interspecies transmission potential

18 Mycoplasma hyosynoviae

19 Clinical disease Characterized by Swollen, soft, and fluctuating joints Acute cases: - One or more limbs may be affected - Slight reduction of appetite accompanied by weight loss Full recovery or stiffness of motion (osteochondrosis)

20 Lesions Synovial membranes: Edema, swelling, hyperemia, proliferation Fibrinous or fibrinopurulent exudate Synovial fluid: Increased volume Serofibrinous or serofibrinous Cloudy, brownish Joint membranes thickened Pseudocysts or calluses on surfaces of joints

21 Diagnostics Method/Test Clinical diagnosis Bacterial culture and isolation Genetic material detection (PCR) Antibody detection Antibiotic susceptibility Molecular characterization Feasibility/Notes Include H. parasuis, S. suis & M. hyosynoviae in differentials Slow Only specific laboratories Rapid results High accuracy Sample type is important Not commercially available Rarely performed, as isolates are needed PFGE, AFLP Whole genome

22 Diagnostics University of Minnesota - VDL

23 Epidemiology Signs persist 3-10 days Usually observed in pigs week-old Lameness due to M. hyosynoviae is perceived as an important problem in the USA Low rate of transmission from sow to piglets Slow spread in the nursery Most pigs colonized by market age

24 100 M. hyosynoviae detection by real time PCR & lameness score 80 % Positive Tonsil Swabs Oral Fluids Lameness 20 0 Dams Newborns Week 3 Week 5 Week 7 Week 10 Week 13 Week 16 Week 19 Week 22 Sample Groups Schwartz et al., 2014

25 100 M. hyosynoviae real time PCR detection in piglets tonsil swab (TS) and oral fluids (OF) samples, and lameness scores (LS) Prevalence of positive detection (%) TS OF LS Week of age Roos et al., 2016

26 Control Developing immunity No commercial vaccine available to date Autogenous vaccines used in the field Maternal immunity? Early exposure and immunity? Stopping the bacterium Antibiotic treatment Early intervention is key Mycoplasmas lack a cell wall Elimination of a commensal bacterium?

27 Knowledge gaps Lack of an infection model Factors that drive spread to joints Timeline of colonization and disease development Real involvement in lameness in the field

28 Mycoplasma hyopneumoniae

29 M. hyopneumoniae infection Adhesin proteins mediate cilia attachment Slow replication Cilia damage is in part mediated by elevated intracellular Ca concentration Chronic evolution Persistence

30 M. hyopneumoniae infection Enzootic Pneumonia Association with other bacterial and viral agents

31 Clinical disease Characterized by Dry cough Decreased average daily gain Increased days to market Mortality can be an issue in naïve herds

32 Lesions Dark lobular consolidation Peribronchial and perivascular lymphocyte proliferation and cuffing Disruption of the epithelial cell lining of the bronchi

33 Importance of respiratory disease in pigs Percentage of grower/finisher phase deaths Source: NAHMS Swine Study APHIS January 2009.

34 Cost of respiratory disease Haden et al., 2012

35 Diagnostics Method/Test Clinical diagnosis Bacterial culture and isolation Genetic material detection (PCR) Antibody detection Antibiotic susceptibility Molecular characterization Feasibility/Notes Include B.bronchiseptica, P. multida, Ascaris suum and IAV in differentials Extremely slow (~ 4 months) Low senstivity Only specific laboratories Rapid results and high accuracy, depending on sample type Several commercial kits available False positives and false negatives Rarely performed, as isolates are needed Most common P146 sequencing and more recently MLVA

36 Acute phase of infection Acute Chronic dpi Adaptation * * * * * ^ Experimental inoculation

37 In vivo detection of M. hyopneumoniae Real-time PCR Laryngeal swab Tracheobronchial lavage Nasal swabs Pieters et al., 2017 Oral fluids

38 Laryngeal swabs

39 Preliminary results Laryngeal swabs and Deep tracheal catheters Courtesy Dr. Sponheim

40 Use of MLVA to type M. hyopneumoniae Multi-Locus Variable-number Tandem-repeat Analysis (MLVA) typing method based on Variable copy Number of Tandem Repeats (VNTR) VNTR loci are selected that are sufficiently discriminatory Conserved primers are designed outside the tandem repeat for each VNTR Vranckx et al., 2011

41 Potential applications Comparing variants within and among farms Outbreak investigations Tracking variants over time

42 Mycoplasma hyopneumoniae outbreak investigation =before elimination strategies =after elimination strategies

43 Epidemiology Worldwide distribution Switzerland (<1% prevalence) Long incubation period (at least 2 weeks) Chronic infection Horizontal and sow-to-piglet transmission are important Airborne transmission demonstrated, even at long distances Lateral infections do not seem to occur frequently

44 Prolonged M. hyopneumoniae infection dpi Acute Chronic 0 ~ Experimental infection Clearance Pieters et al., 2009

45 Piglet probability of being M. hyopneumoniae PCR + is associated with dam s PCR status Pieters et al., 2014

46 Sow parity influences shedding Parity Tested piglets Positive piglets Prevalence at weaning Young a Intermediate b Old b Fano et al., 2007

47 Prevalence at weaning can be a predictor of disease severity in growing pigs Correlation analysis Independent Variable = Prevalence at weaning Dependent Variable r 2 P-Value Percent affected lungs Average lung lesion score Seroconversion Final prevalence (PCR) Fano et al., 2007

48 Transmission among penmates Basic reproductive number(r 0 ): Transmission experiments SIR system Slow R 0 :1.16 Meyns et al., 2004

49 Control Developing immunity Commercial bacterins commonly used: Expectations and limitations need to be clearly understood Maternal immunity and piglet vaccination Vaccines Stopping the bacterium Management changes Antibiotic treatment Early intervention is key for successful control Elimination programs Antimicrobials Management

50 Effective control is comprehensive Grow-finish Site(s) Sow herd Dam Piglet Replacement Incoming gilts Recipient herd

51 management for gilt acclimation to M. hyopneumoniae Pieters & Fano, 2016

52 Achieving uniform pathogen exposure is challenging Roos et al., 2016

53 Exposure methods Natural contact Intratracheal inoculation Aerosol exposure Courtesy Dr. Sponheim

54 Eradication/Elimination Most common protocols in USA Depopulation/Repopulation Herd closure and medication Whole herd medication without herd closure Historic protocol in Europe Partial depopulation

55 Host et al., 2015

56 Estimated cost of a herd closure and medication program Hypothetic farm 2500 sows 25 P/S/Y Quarterly vaccination Animals Drug Dose Route Frequency Duration Dams Macrolide Per label Water Continuous 2 weeks Piglets Macrolide Per label IM Birth & 14 days after 4 weeks Approximate cost $41.69 per sow Estimated increase in production $1.19 per piglet 16.7 ROI Yeske, 2010

57 Take home message Diseases caused by Mycoplasma species in swine are prevalent and relevant Addressing knowledge gaps is the first step toward effective control

58 Thanks!