# Presentation: 786800

## The epidemiology of Mycoplasma hyopneumoniae

- Eric Bush
- USDA:APHIS:VS
- FDA:CVM
- Swine Mycoplasma
- Pneumonia Workshop
- Kansas City, MO
- March 6, 2002

## Objective:  Respiratory disease

- Porcine Respiratory Disease Complex (PRDC)
- Prevalence of primary pathogens
- Severity of condition
- mortality due to respiratory illness
- age of onset in grower/finisher
- course of treatment
- Extent of control measures and their relation to prevalence and severity

- Swine 2000

**Notes:**
both serology (OD; PRRS herd classification) and producer reported.
severity:  morbidity=culls
Control measures association with prevalence and severity.  Also, are right control measures being taken under right situations.  E.g. vaccination of pigs if continuous flow op

Mortality rate due to respiratory disease:   3% of preweaned pigs; 30% nursery age pigs;  40% of g/f pigs

## Swine 2000 study design

- NASS General Swine Farm Report
- June 1 – July 14, 2000
- n=2499 respondents
- VS Initial VMO visit
- August 21 – November 3, 2000
- n=895 respondents
- VS Second VMO visit
- December 1, 2000 – March 15, 2001

**Ref:  USDA:APHIS:VS. Part I:  Reference of Swine Health and Management **
**in the United States, 2000. Fort Collins, CO:NAHMS; 2001 August.**

- Swine 2000

**Notes:**
Antibiotic use data collected on the first VMO visit – done last fall; done by vets.

More details on the design and implementation of the study, including results from the GSFR, are available in Part I report.

## Objective:  Serum bank

- Create national serum bank
- Epidemiological description of endemic pathogens
- prevalence
- distribution
- risk factors
- Natural history of emerging diseases
- time of emergence
- epidemiological description

- Swine 2000

**Notes:**
Breeding females and late finishers
Current swine conditions and emerging diseases
“Respiratory disease” package:  30 sows samples; 15 finisher samples; 
Results:  506 sites; 14,328 samples (5862 fin; 8466 breeders).

## Swine 2000 study design Blood collection

- Voluntary participation
- Collection from sows/gilts
- Max of 30 samples
- Quota sampling by parity
- Collection from finishers
- Max of 15 samples
- Across pens (max of 10 pens)
- Must be 20 weeks or older
- Shipped overnight on ice to NVSL.

**Notes:**
Lose selection probabilities; therefore ability to weight and reference the national population.
Quota sampling = 1/3 from parity 0-1; 1/3 from parity 2-3; and 1/3 from parity 4+

## Swine 2000 study design Blood collection

- Testing:
- PRRS -  ELISA test at NVSL.
- Mycoplasma – Tween20 ELISA test at ISU (Pfizer).
- Mycoplasma - IDEXX ELISA test at BI/Vetmedica.
- SIV - HI test at WI (Schering-Plough).
- Serum banked for further use.
- 5 of 8 sets left

## Swine 2000

**Notes:**
Selection criteria for study:
 Respondents that owned or operated pork production sites located in top 17 swine producing states.
 Repondent had a total inventory on March 1, 2000 of at least 100 hogs.  Based on NASS Hogs and Pigs report.

Response from this national swine survey are weighted and used to estimate practices for the ‘pork industry’ as a whole.  This study covers / represents 94% of the total US hog inventory and 92% of operations with 100+ total inventory.

This applies to questionnaire data, not biological results.

## Swine 2000 Blood collection

- Finishers only		200
- Breeding only		111
- Both				195
- Total 				506 sites----------------------------------------
- 14,328 samples collected from 506 sites.
- 8466 sow/gilt samples from 306 sites
- 5862 finisher samples from 395 sites.

**Notes:**
Any finishers:  395
Any breeding:  306

## Mycoplasma (ISU) results

- Site prevalence:
- Finishers:  82.3%
- Breeding:  94.8%
- Animal prevalence
- Finishers:  48.9%
- Breeding:  38.3%

- Swine 2000

**Notes:**
Site prevalence:  
	Finishers:  lowest in WestCentral (74%) and highest in South (90%); lower on finisher only sites (77%) vs Frw-Fin sites.
	Breeding:  range across regions=90-100%.

With-in herd prevalence:
	Finishers:  bi-modal; either few positive or most positive
	Breeding:  most with few positive

## 	Any questions

## How does site prevalence vary...

- By region?
- By type of site?
- By size of site?
- Vaccine status of site?
- By visit blood collected (season)?

## Slide 12

## Site prevalence, by type

- Finishers only		77.5%
- Breeding only		97.3%
- Both				97.4%
- All sites			89.5% sites

**Notes:**
Any finishers:  395
Any breeding:  306

## Site prevalence, by total inventory

| <2000 | 2000-9999 | 10,000+ |
| --- | --- | --- |
| 83.9 | 80.6 | 80.8 |
|  |  |  |
| <2000 | 2000-9999 | 10,000+ |
| 93.1 | 98.1 | 92.3 |

- Swine 2000

- Sites with breeding females

- Sites with finisher

**Notes:**
Didn’t matter is I looked at by market hog inventory and sow inventory or by total inventory – very similar estimates.
No association with size.

## Site prevalence, by vaccination status

| Do vaccinate |  |  |  | Don’t Vaccinate |
| --- | --- | --- | --- | --- |
| 88.4 |  |  |  | 77.1 |
|  |  |  |  |  |
| Do vaccinate |  |  | Don’t Vaccinate |  |
| 97.8 |  |  | 93.5 |  |

- Swine 2000

- Sites which vaccinate breeding females

- Sites which vaccinate finishers

## Site prevalence, by visit (season)

| First visit |  |  |  | Second visit |
| --- | --- | --- | --- | --- |
| 88.5% |  |  |  | 79.2% |
|  |  |  |  |  |
| First visit |  |  | Second visit |  |
| 76.9 |  |  | 94.9 |  |

- Swine 2000

- Sites with breeding females

- Sites with finishers

**Notes:**
Finishers:
First visit, Jul-Nov – 115/130
Second visit, Dec-Mar – 209/264

Breeding females:
1st visit – 100/130
2nd visit – 188/198

## What about the prevalence within sites (herds)?

- How does it vary by pig type?

## Distribution of sites by number of positive finishers

- Swine 2000

**Mean = 48.9%**

**Notes:**
Bi-modal distribution, either very few positive or a bunch of them are positive.
Mean within herd prevalence = 48.9%

## Distribution of sites by number of positive breeding females

- Swine 2000

**Mean = 37.4%**

**Notes:**
Skewed left – ie most sites have at least some positive sows/gilts (that’s why site prevalence for sows/gilts is so high) BUT those sites usually have only a portion of them that are positive.
Mean within herd prevalence = 37.4%

## How does animal prevalence vary...

- By region?
- By size of site?
- By gender of finishers?
- By parity of breeding females?
- Vaccine status of animal?

## 56.9%

**56.9%**
**41.7%**

**42.7%**
**36.1%**

**47.7%**
**37.0%**

**51.2%**
**38.5%**

## Animal prevalence, by total inventory

| <2000 | 2000-9999 | 10,000+ |
| --- | --- | --- |
| 50.2 | 47.9 | 45.3 |
|  |  |  |
| <2000 | 2000-9999 | 10,000+ |
| 36.5 | 38.6 | 47.9 |

- Swine 2000

- Percent breeding females that were positive

- Percent late finishers that were positive

## Finisher prevalence, by gender

- Gilts				46.0%
- Barrows			50.8%
- All late finishers		48.9%

**Notes:**
Gilts – 2353 tested
Barrows – 2947 tested
Total – 5851  (several hundred without gender information)
Difference is significant (p=0.002)

## Slide 24

**Notes:**

Negative – very skewed to left
Suspect – slightly skewed to left
Neg results – normal distribution of parity; 

## Animal prevalence, by vaccination status

| Vaccinated |  |  |  | Not vaccinated |
| --- | --- | --- | --- | --- |
| 56.1 |  |  |  | 43.3 |
|  |  |  |  |  |
| Vaccinated |  |  | Not vaccinated |  |
| 49.8 |  |  | 32.1 |  |

- Swine 2000

- Percent of vaccinated sows/gilts that were positive

- Percent of vaccinated finishers that were positive

## Other mycoplasma data

- Prevalence of mycoplasma as reported by respondents
- Vaccination practices
- Other control strategies

## Prevalence of selected diseases in nursery pigs, by herd size

- Swine 2000

**Notes:**
Herd size:  <2000; 2000-9999; 10,000+ total inventory.   
Nursery age:  weaned to 70lbs; different types of sites – frw to finisher; wean-finish; nursery site only
Regardless of herd size, the most prevalent disease condition in the nursery-age pigs was Streptococcus suis (meningitis).  The other more prevalent diseases  depended on herd size.  Greasy pig being the second most common disease reported on sites with <10,000 total inventory.  Mycoplasma pneumonia being the third most common disease reported on sites with >2000 total inventory. 

APP:  had declined since 1990 in all size groups, especially large.
SIV and Mycoplasma: have increased a lot since 1990 for medium size herds; mycoplasma is flat for large herds; SIV is up a lot in large herds.

PMWS:  In Dec 00, England/Wales had 20% farms positive, similar to our prevalence in our large sites.  Source=ProMed 11/5/01
Strep suis:  Most prevalent disease of nursery-age pigs, regardless of herd size.
Staph hyicus: For small / medium sites it is the second most prevalent disease in nursery age pigs.

## Prevalence of selected diseases in grow/finish pigs, by herd size

- Swine 2000

**Notes:**
Herd size:  <2000; 2000-9999; 10,000+ total inventory.  Grow/finish=weaned 70+ lb pig. 

Ileitis is the most common problem on sites with g/f pigs, regardless of size.  Mycoplasma is a close second.
Then PRRS; then SIV.  SIV H1N1 is more common than SIV H3N2, though not by much.

APP:  had declined since 1990 in all size groups, especially large.
SIV and Mycoplasma: have increased a lot since 1990 for medium size herds; mycoplasma is flat for large herds; SIV is up a lot in large herds.

APP, Mycoplasma, SIV are more prevalent in g/f than nursery.  PRRS is about the same.  PMWS is more prevalent in nursery age pigs.

## Mycoplasma vaccination – breeding females

**15.4%**

**43.6%**

**46.2%**

- Swine 2000

**Notes:**
This is percent sites.  
Percent breeding females:  40% sows/gilts are vaccinated for mycoplasma.

## Mycoplasma vaccination – breeding females

| Prior to entry | At entry | In the herd | 
<250 | 250-499 | 
500 + |
| --- | --- | --- | --- | --- | --- |
| Yes | Yes | Yes | 23.1 | 14.0 | 26.1 |
| Yes | Yes | No | 3.4 | 15.6 | 24.5 |
| Yes | No | Yes | 5.3 | 5.9 | 6.2 |
| No | Yes | Yes | 7.8 | 11.1 | 0.0 |
| Yes | No | No | 42.2 | 41.4 | 18.7 |
| No | Yes | No | 6.0 | 8.7 | 24.5 |
| No | No | Yes | 12.2 | 3.3 | 0.0 |

**Notes:**
As a percent of those sites that vaccinate for mycoplasma.  Totals 100%.

For over half of the vaccinated breeding herds, breeding females receive only one vaccination.  On most sites this is prior to entry into the breeding herd (41.3% of sites) but may also occur at time of entry (7.4%) or after entry (8.9%).  One fifth of vaccinated breeding herds vaccinate all three times. 

## Number of mycoplasma vaccinations received by breeding females

- Swine 2000

## Percent sites using vaccine to control mycoplasma in weaned market pigs, by herd size

- Swine 2000

**Notes:**
Herd size:  <2000; 2000-9999; 10,000+ total inventory.  Grow/finish=weaned 70+ lb pig. 

Vaccinate sows/gilts
Vaccinate pigs le 70 lbs
Vaccinate pigs >70 lbs;  ie grower/finisher, after nursery

## Number of mycoplasma vaccinations received by weaned market pigs

- Swine 2000

## Mycoplasma vaccination – age weaned market pigs are vaccinated (weeks)

| 
Dose | 
<2000 | 2000-9999 | 
10,000 + |
| --- | --- | --- | --- |
| 1st & only | 7.4 | 7.7 | 6.9 |
|  |  |  |  |
|  |  |  |  |

- Swine 2000

**Notes:**
The average age the first mycoplasma vaccine is given depends on whether it is the only dose (7.5 weeks) or the first of two doses (3.4 weeks).  The average age the second dose is given depends on herd size, ranging from 6.2 weeks on small sites to 9.3 weeks on large sites. 

## Mycoplasma vaccination – age weaned market pigs are vaccinated (weeks)

| 
Dose | 
<2000 | 2000-9999 | 
10,000 + |
| --- | --- | --- | --- |
| 1st & only | 7.4 | 7.7 | 6.9 |
| 1st of two | 3.2 | 4.1 | 3.4 |
|  |  |  |  |

- Swine 2000

**Notes:**
The average age the first mycoplasma vaccine is given depends on whether it is the only dose (7.5 weeks) or the first of two doses (3.4 weeks).  The average age the second dose is given depends on herd size, ranging from 6.2 weeks on small sites to 9.3 weeks on large sites. 

## Mycoplasma vaccination – age weaned market pigs are vaccinated (weeks)

| 
Dose | 
<2000 | 2000-9999 | 
10,000 + |
| --- | --- | --- | --- |
| 1st & only | 7.4 | 7.7 | 6.9 |
| 1st of two | 3.2 | 4.1 | 3.4 |
| 2nd of two | 6.2 | 7.4 | 9.3 |

- Swine 2000

**Notes:**
The average age the first mycoplasma vaccine is given depends on whether it is the only dose (7.5 weeks) or the first of two doses (3.4 weeks).  The average age the second dose is given depends on herd size, ranging from 6.2 weeks on small sites to 9.3 weeks on large sites. 

## Strategies employed to control mycoplasma in weaned market pigs, by herd size

- Swine 2000

**Notes:**
Herd size:  <2000; 2000-9999; 10,000+ total inventory.  Grow/finish=weaned 70+ lb pig. 

Early wean (le 16 days) with NO antibiotics 
Early wean (le 16 days) with antibiotics 
Wean >16 days with antibiotics 
AIAO farrowing phase
AIAO nursery phase
Treat pigs showing clinical signs of pneumonia with antibiotics 
Treat healthy pigs sharing air space with sick pigs with antibiotics 
Any of the above measures (including vaccination which is not shown on this slide).

## Acknowledgments

- National Agricultural Statistics Service (NASS)
- NAHMS Design and Implementation team
- State and Federal Veterinary Medical Officers, VS field
- APHIS:  National Veterinary Services Laboratories (NVSL)
- ARS: Russel Research Center
- ARS: Eastern Regional Research Center
- ARS:  National Animal Disease Center
- U.S. Food and Drug Administration (FDA-CVM)
- National Pork Board
- American Association of Swine Veterinarians (AASV)
- Pfizer
- Boehringer Ingelheim Vetmedica
- IDEXX Laboratories, Inc.
- Schering-Plough
- Iowa State University
- The Ohio State University
- University of Illinois
- University of Tennessee
- University of Wisconsin – Madison

- Swine 2000

**Notes:**
Particularly NAHMS staff; field force; NPB; AASV; FDA

## For more information:

- Eric Bush
- USDA:APHIS:VS-CEAH
- 555 S Howes
- Fort Collins, CO.  80521
- (970) 490-8000
- _[Eric.J.Bush@aphis.usda.gov](mailto:Eric.J.Bush@aphis.usda.gov)_
- Or search for “NAHMS swine” on the web.