Kimberlee Gerardy - A Systematic Approach to PRRS Outbreak Investigations

IOWA STATE UNIVERSITYVeterinary Diagnostic and Production Animal Medicine

Outbreak Investigation Program:A Systematic Approach to PRRS Outbreak Investigations

Kimberlee Gerardy

2015 North American PRRS Symposium

December 6th, 2015Chicago, IL


PRRSV Research Focuses on Two Areas

1. How do we return to baseline productivity faster after a break?

2. How do we keep PRRSV out?– 20 - 40% breeding herds have outbreaks annually (Swine

Health Monitoring Project, November 13, 2015)


Outbreak Investigation Program• Pilot project was developed in 2013 through funding

by the Iowa Pork Producers Association (Checkoff $)

• Work with PRRS Regional Control Projects in Iowa– Share PRRSV history and production data for aggregate

analysis– Investigate PRRS outbreaks within the project

• 29 breeding herds currently enrolled in the pilot


Objectives• Enhance knowledge of PRRSV spread and

prevention by investigating outbreaks in a timely, efficient, and uniform manner

• Determine most common gaps in biosecurity that may have lead to PRRSV introduction


Methods: Standard Outbreak Investigation Form

• Background / Demographic Info– PRRSV History– Herd Characteristics– Premise Characteristics– Current Outbreak

• Questions on a set of risk events known to happen on farm and associated carrying agents


Methods: Risk Events• Swine Movements– Semen– Gilts– Culls– Weaned Pigs

• Vehicles / Deliveries– Dead disposal– Feed– Propane / fuel– Garbage– Tools / Supplies

• People Movement– On-farm employees– Repair inside / outside barns– Other visitors (vets, vendors,

etc)• Pork / food product entry• Manure Removal• Other Animals• Air / Water


Methods: Investigation• Interview– Veterinary outbreak facilitators– Herd veterinarians– Farm personnel

• Investigation Period: 4 weeks preceding the suspected onset


Methods: Written Report• Identifies the likelihood

that each event was responsible for PRRSV introduction– Low– Medium– High

• Recommendations for biosecurity improvements


Methods: Assignment of Risk Ratings

• Risk events are paired with multiple carrying agents

• Semen Entry– Semen– Semen packaging &

container(s)– Semen courier– Semen delivery vehicle

• Risk rating determined by:– Frequency of event

– Likelihood that a carrying agent is contaminated with PRRSV

– Likelihood that PRRSV gets from carrying agent to pigs in the herd


Farms Investigated• 8 outbreak investigations between Jan 2015 – Aug 2015– All independent farrow-to-wean farms

Characteristic Farm 1 Farm 2 Farm 3 Farm 4 Farm 5 Farm 6 Farm 7 Farm 8Herd Size

(# sows) 670 1200 550 600 850 1085 1200 650

PRRSV Isolate 1-26-2 1-26-2 1-26-2 1-7-4 1-7-4 1-4-4 1-7-4 1-4-4

# Swine Sites within

5 Miles15 27 28 24 38 10 27 32

# PRRSV Outbreaks in Last 5

Years2 3 2 3 1 1 4 3


Frequency of Risk EventsRisk Event Min Max Average (%)

Swine Movement

7 25 17 (9%)

Vehicles / Deliveries

9 39 17 (9%)

People Movement

42 114 91 (50%)

Pork / Food Entry

0 112 56 (31%)

Manure Removal

0 1 0.1 (<1%)

Total Risk Events

84 258 181.1

Large Farm Average44 31

330 282 3

690

Data from 8 medium sized (~850 sow) breeding herds

Data from 5 large (4500 sow)

breeding herds


Events Rated High or Medium Risk for PRRSV Introduction

Cull So

ws

Feed

Delive

rieis

On-Farm

Emplo

yees

Dead R

emov

al

Repair

Insid

e Barn

sSe

men

New Su

pplie

s

Transf

erred

Supp

lies

Air/W

ater

Replac

emen

t Gilts

Other V

isitors

Weane

d Pigs

Manure

equip

ment /

pers.

..

Repair

Outside

Barns

012345678

1 1

4

1 1 1 1

42

4

1 1

5 4

3

2 2 1

# T

imes

Ran

ked

Hig

h or

Med

Ris

k

High Risk

Medium Risk


On-Farm Employees: Biosecurity Gaps & Connections

• Most frequent event on-farm

• Employees did not always practice downtime

• Sow farm employees worked at other swine sites or in other aspects of swine production (i.e. feed mills, market hog transport, etc.)

• Sanitation procedures were relaxed for employees that needed to exit and re-enter sow unit on the same day


Cull Sow Movement: Biosecurity Gaps & Connections

• Cull sow transport was normally contracted non-exclusively to a 3rd party

• Trucks / trailers hauled multiple types of swine with no or unknown sanitation procedures

• Cull sow drivers and on-farm employees rarely observed lines of separation


Feed Delivery: Biosecurity Gaps & Connections

• Feed mill biosecurity practices were highly variable

• Feed mill was located on a PRRS positive sow farm

• Feed mill equipment was shared with compost equipment in 3 outbreaks


Operational Connections• Repairmen and their equipment worked at multiple

swine sites and did not practice downtime between the positive and negative sites

Farm A

Farm B

Farm C

Farm B

Farm C


Conclusions• Timely identification of gaps in biosecurity– Identify most cost-effective biosecurity measures for the producer

• Immediate feedback after an outbreak

• Applicable to other endemic and emerging diseases– PEDV– Senecavirus A (SVA)

• People were high risk– Improved communication among personnel was needed– Additional layers of biosecurity were needed


Acknowledgements• Iowa Pork Producers

Association• Iowa State University

Faculty and Staff– Derald Holtkamp– Christine Mowrer– Abbey Canon– SMEC

• SVIP Interns– Cassandra Fitzgerald and

Allysa Koethe

• Regional Project Coordinators– Cindy Gentz– Sonya Maas– Shamus Brown

• Producers and veterinarians of farms investigated


Questions?


Introduction of pathogens into a herd is the result of a series of “events” and “failures”

Carrying agent enters farm?

NoNo Risk

YesCarrying agent is

contaminated w/infectious pathogen?

NoNoRisk

Yes

Pathogen gets from carrying

agent to pigs in herd? Herd is

infected

NoRisk

NoYes

The 2015 North American PRRS Symposium wishes to thank the following sponsors for their generous

support:

Kimberlee Gerardy - A Systematic Approach to PRRS Outbreak Investigations

Health & Medicine

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