1

Current public health problems related to pork

Arie HavelaarBrussels, 25 October 2010

2

Main hazards associated with pork consumption

● Campylobacter spp.● Listeria monocytogenes● Mycobacterium spp.● Salmonella spp.● Staphylococcus aureus● VTEC● Yersinia spp.

● Hepatitis E virus

● Ascaris suum● Echinococcus spp.● Cryptosporidium spp.● Taenia solium● Trichinella spp.● Toxoplasma gondii

● Antimicrobial resistance

Source: EFSA Opinion 613

3

What are the risks and how do they compare?

●Epidemiology–Incidence–Mortality–Severity–Attribution

●(Comparative) risk assessment–Risk Ranger–sQMRA–iRisk

4

Data on human illness at EU level

● Available data in Annual Community Summary Report on Trends and Sources of Zoonoses and Zoonotic Agents and Food-borne Outbreaks in the European Union (Annual)

5

Main hazards associated with pork consumption:data availability EU

● Campylobacter spp.● Listeria monocytogenes● Mycobacterium spp.● Salmonella spp.● Staphylococcus aureus● VTEC● Yersinia spp.

● Hepatitis E virus

● Ascaris suum● Echinococcus spp.● Cryptosporidium spp.● Taenia solium● Trichinella spp.● Toxoplasma gondii

● Antimicrobial resistance

6

Foodborne outbreaks in 2008

Source: Community Summary Report 2008 (EFSA, 2010)

7

Reported incidence of human salmonellosisin the EU

Source: Community Summary Report 2008 (EFSA, 2010)

8

The surveillance pyramid for gastrointestinal pathogens

# cases of AGI in community, due to specific pathogen

# cases seeking medical care

# cases submitting stool sample

# tested for pathogen

# positive lab results

# reported cases

# asymptomatic infections with specific pathogen in community

sero-survey of population

Methods used for calibration:

Cohort studies

Multiplier methods

Travelers as sentinels

Modelling

Seroepidemiology

Reported fraction differs between countries and

between diseases

9

Reported salmonella infectionsper 1000 py

< 0.20.2 - 0.40.41 - 0.5

Source: dr. K. Mølbak, SSI, Denmark

10

Salmonella sero-incidenceper 1000 py

< 100100 - 300301 - 550

Source: dr. K. Mølbak, SSI, Denmark

11

Salmonella sero-incidence and incidence estimates in Swedish travelers

0

10000

20000

30000

40000

50000

60000

1 10 100 1000 10000

incidence / 100000 by Swedish travellers

sero

-inci

den

ce /

1000

00

Spearman’s rho=0.9, p=0.007

* D

ata

fro

m:

de

Jo

ng

B,

Ekd

ah

l K.

Th

e c

om

pa

rativ

e b

urd

en

of

salm

on

ello

sis

in t

he

Eu

rop

ea

n U

nio

n m

em

be

r st

ate

s,

ass

oci

ate

d a

nd

ca

nd

ida

te c

ou

ntr

ies.

BM

C P

ub

lic H

ea

lth 2

00

6;

6:4

d

oi:1

0.1

18

6/1

47

1-2

45

8-6

-4

Source: dr. K. Mølbak, SSI, Denmark

12

Salmonella prevalence in layers (baseline study, all serovars) and sero-incidence

Spearman’s rho=0.90, p=0.005

FR

0

10000

20000

30000

40000

50000

60000

0.1 1 10 100

layer hen holding prevalence (%)

sero

-in

cid

ence

/ 1

0000

0

FR

Source: dr. K. Mølbak, SSI, Denmark

13

What are the priorities?

Outcome Norovirus Rotavirus Campylo-bacter

Salmonella

Gastro-enteritis

640,000 300,000 79,000 43,000

GE – visit to GP

16,000 21,000 19,000 7,600

GE – hospital

2,000 4,400 570 650

GE – death

6 2 46 47

Reactive arthrititis

- - 1,500 1,700

Guillain-Barré S.

- - 65 -

Irr. Bowel Syndrome

- - 6,900 3,900

14

HALYs: integrated measures of disease burden

● Integrate morbidity and mortality● Incorporate age and health status of those affected● Address incidence, severity and duration of adverse health

consequences● One example, frequently used in public health:

Disability Adjusted Life Years

DALY = YLL + YLD– mortality: years of life lost

YLL = all diseases ( D x e)D: number of deaths; e: life expectancy of fatal cases

– morbidity: years lived with disability, weighted for severity of illness

YLD = all diseases ( N x t x w)N: number of non-fatal cases; t: duration, w: severity weight

15

Disease burden in the Netherlands (all sources)

0

500

1.000

1.500

2.000

2.500

Campylobacter

Noroviru

s

Salmonell

a

Rotaviru

s

Toxoplasma (

cong.)

S. aureu

s

C. perfr

ingens

Listeri

a

G. lamblia

STEC O157

Hepatiti

s E viru

s

B. cere

us

Hepatiti

s A viru

s

Cryptosp

oridium

DA

LY

s pe

r ye

ar

Not discounted Discounted (4%)

Campylobacter has the highest

burden

Burden of Toxoplasma very uncertain, recent data suggest 4x higher burden

Strong effect of discounting

(child deaths)

16

Disease burden per case

1

10

100

1000

10000

100000

L. m

onoc

ytoge

nes (

perin

atal)

T. go

ndii (

cong

enita

l)

L. m

onoc

ytoge

nes (

acqu

ired)

Hepa

titis

E viru

s

Hepa

titis

A vir

us

STEC

O15

7

Salm

onell

a spp

.

Cam

pylob

acter

spp.

C. pe

rfring

ens

Rotav

irus

S. au

reus

B. ce

reus

Noro

virus

C. pa

rvum

G. la

mbli

a

DA

LY p

er

1000 c

ase

s

undiscounted

discounted

Diseases affecting unborn or young children have the highest

burdenSystemic

infections also have a high

burden

Lowest burden for protozoa

17

Attribution

●The partitioning of the human disease burden of one or more foodborne infections to specific sources (animal reservoirs and vehicles such as foods)

●Microbiological approaches–Microbial subtyping–Comparative exposure assessment

●Epidemiological approaches–Case-control studies of sporadic infections–Outbreak investigations

●Intervention studies–Surveillance after new legislation–Natural experiments

●Expert elicitation

●Currently most data available for Salmonella

18

Attribution of salmonellosis in the Netherlands, 1984-2009

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008

lab

-co

nfi

rme

d c

as

es

of

sa

lmo

ne

llos

is

0

20000

40000

60000

80000

100000

120000

140000

160000

Sa

lmo

ne

llos

is c

as

es

, ge

ne

ral p

op

ula

tio

n

Singled out Explosionstravel/otherCattlePigsLayers/Repro/EggsBroilers/products

Manure

transports

ST DT104

AI outbreak

Spanish egg

imports

Peak Enteritidis epidemic

Improved slaughter hygiene

Poultry control program

Italian

cattle meat

ST DT104

Cheese

incident

ST DT7

Dairy (ST DT15A)

J uice (Panama)

Butcher Trnzn(ft507)

Beef (ST qDT104)

Egg (SE Pt8)

? Gr. Fr. (ft507)

raw cattle

products

ST ft90

ST ft132

Source: dr. Wilfrid van Pelt, RIVM, the Netherlands

19

Estimated major sources of human salmonellosis in Denmark, 1988-2009

Source: prof. Tine Hald, Food-DTU, Denmark

10-20% of human

Salmonella infections

in EU may be attributable

to the pig reservoir as a whole

EFSA Opinion 1547, 2010

20

Monophasic Salmonella (1,4,[5],12:i)

● … are regarded as variants deriving from S. Typhimurium

● … have been shown to have similar virulence and antimicrobial resistance characteristics to strains of S. Typhimurium

● … the third most common serovar from human infections

● …. the second most common serovar from pigs

● …. the third serovar from bovine samples

Source: EFSA Opinion 1826

21

Attribution of the burden of 14 pathogensto major pathways in the Netherlands

Disease burden (DALY per year)

Food50%

Environment18%

Human22%

Animal10%

Estimates based on expert elicitation

22

Attribution of the foodborne burden of 14 pathogensto food groups in the Netherlands

Disease burden (DALY per year)

Beef and mutton15%

Pork12%

Poultry19%

Eggs6%

Dairy9%

Cereal products4%

Other food11%

Human and animal9%

Fish and shellfish7%

Fruit and vegetables6%

Beverages2%

Estimates based on expert elicitation

Mainly T. gondii and Salmonella spp.

23

Filling the data gaps

● ECDC– Burden of Communicable Diseases in Europe– Sero-epidemiology of Salmonella and Campylobacter

● WHO– Foodborne Epidemiology Disease Burden Reference Group

24

Conclusions

● Surveillance systems for the main pathogens in pork are in place in the EU, but coverage varies between Member States

● Reported data represent only a fraction of all cases in the population

● The reported fraction varies strongly between Member States and between pathogens

● Severity of acute illness, sequelae and mortality need to be taken into account when deciding about public health priorities

● Data for attribution of human illness to animal reservoirs and foods are poorly available

● Major international projects are on-going to fill data gaps, but Member States need to invest in more systematic surveillance

● Based on current evidence, Salmonella spp., Toxoplasma gondii and Trichinella spp. appear to be the most important pathogens in pork