Bayesian estimation of prevalence of paratuberculosis in da…

Preventive Veterinary Medicine 128

(2016) 95–100

Contents

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Preventive Veterinary Medicine

journal

homepage: www.elsevier.com/locate/prevetmed

Bayesian estimation of prevalence of paratuberculosis

in dairy herds

in a voluntary

Johne’s Disease Control Programme in

Ireland

enrolled

Conor G. McAloon a , ∗ , Michael

L. Doherty a , Paul Whyte a ,

Luke O’Grady a , Simon

J. More a ,

L. McV. Messam a , Margaret Good b , Peter Mullowney b , Sam Strain c ,

Locksley

Martin J. Green d a School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4,

Ireland

b Department of Agriculture,

Food and

the Marine, Kildare

Street, Dublin 2,

Ireland

c Animal Health

Ireland, Carrick-on-Shannon, Co.

Leitrim,

Ireland

d School of Veterinary Medicine and

Science, University of Nottingham,

Sutton Bonington, United Kingdom

a

r

t

i

c

l

e

i

n

f

o

a

b

s

t

r

a

c

t

Article history: Received 11 December 2015 Received in revised

Bovine paratuberculosis is

a disease

characterised by

chronic

granulomatous

enteritis which manifests

clinically

as

a

protein-losing

enteropathy

causing

diarrhoea,

hypoproteinaemia,

emaciation

and,

even-

form 18 March 2016

tually

death.

Some

evidence

exists

to

suggest

a

possible

zoonotic

link

and

a national

voluntary

Johne’s

Accepted 25 April 2016

Disease Control Programme was

initiated by Animal Health

Ireland

in 2013.

The objective of

this

study

was losis

to estimate herd-level Irish herds enrolled in

true prevalence

(HTP) and animal-level

true prevalence

(ATP) of paratubercu-

Keywords: Paratuberculosis Dairy Ireland Prevalence Bayesian

in the national voluntary

JD control programme during 2013–14. Two datasets

were used from 119 herds), andwas used to construct model priors. Model priors were updatedwith a primary (2013–14) dataset which included test records from 99,101 animals in 1039 dairy herds and was generated as part of the national voluntary JD control programme. The posterior estimate of HTP from the final Bayesian model was 0.23–0.34 with a 95% probability. Across all herds, the median ATP was found to be 0.032 (0.009, 0.145). This study represents the first use of Bayesian methodology to estimate the prevalence of paratuberculosis in Irish dairy herds. The HTP estimate was higher than previous Irish estimates but still lower than estimates from other major dairy producing countries. © 2016 Elsevier B.V. All rights reserved. in this study. The first dataset had been collected in Ireland during 2005 (5822 animals

1.

Introduction

dairy

producing

countries

have

introduced

control

programmes

reducing overall prevalence

( Geraghty et al., 2014 ).

aimed at

Animal

Bovine

paratuberculosis

is

a

disease

characterised

by

chronic protein-

Health

Ireland

(AHI)

was

formed

as

a

not-for-profit

enteritis which manifests

clinically

as

a

providing

national

leadership

and

coordination

of

granulomatous

organisation

losing ation

enteropathy

causing

diarrhoea, ( Sweeney,

hypoproteinaemia,

emaci-

non-regulatory

animal health

issues

in

Ireland

( More

et

al., 2011 ).

and,

eventually

death

2011 ).

Adverse

effects

on

AHI

Johne’s

Disease

Control

Programme was

developed

and true 20%,

The

animal productivity

introduced as a voluntary programme

in

terms of

lower milk yield, higher

cull

rates,

in 2013.

Irish herd-level

reduced

prevalence based on siderably ( Nielsen

value

for

culled

animals,

possible

adverse

effects

on

fer- key

(HTP)

on

dairy

farms

in

2005 was

estimated

at

tility

and

losses

due

to

continued

spread

of

infection

are

the

results of a serological survey

( Good et al., 2009 ), con-

drivers

in

the attempt

to

control

the disease at

farm

level.

In addi-

lower

than

estimates

across

Europe

of

greater

than

50% EU,

tion

some

research

exists

to

suggest

that

the

aetiologic

pathogen

and

Toft,

2009 ).

In

common with

trends

across

the

the number of dairy herds in

subspecies paratuberculosis

(MAP) may pose

Ireland has been gradually decreasing

Mycobacterium avium

a

whilst

zoonotic

risk

herd

sizes

( Chiodini

et

al.,

2012 ).

Consequently, many major

have

increased.

It

is

therefore

possible

that HTP

in

the

intervening years.

has altered

Measuring

the impact of control programmes requires an

initial

baseline estimation of chronic diseases of slowor incidence may be difficult

the occurrence of

infection.

In

the context of

∗ Corresponding author at: Section of Herd Health and Animal Husbandry, School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland. E-mail addresses: mcaloonconor@gmail.com , conor.mc-aloon@ucdconnect.ie (C.G. McAloon).

insidious onset such as paratuberculosis,

to calculate and prevalence

is often used

instead

( Messam et al., 2008 ). A review of

the prevalence of paratu-

http://dx.doi.org/10.1016/j.prevetmed.2016.04.014 0167-5877/© 2016 Elsevier B.V. All rights reserved.

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