Download QMRA for Ingestion of Bacterial Contamination of

QMRA for Ingestion of Bacterial
Contamination of Paneer in
Mumbai, India
Hannah P Sassi, Aaron Bivins, Aurelie Pohl,
Bradley Lampe, Mehran Ghasemlou, Hao
Pang and Sandhya Shrivastava
Overview
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Background/Introduction
Problem Statement
Hazard ID
Dose Response
Exposure Assessment
Risk Characterization
Risk Management
Introduction
• Paneer is a South Asian variety of soft cheese in raw form
or in preparation of several varieties of culinary dishes
• Rich source of animal protein, fat, vitamins and minerals
and high in digestibility
• 5% of milk produced in India is converted to paneer
(4,496 metric tons and growing)
• Mechanized and controlled commercial manufacturing
process (refrigerated shelf life 5-15days)
• Preference is for fresh paneer: unorganized sector (small
producers)
• Concerns for consumer and product safety due to low
quality milk, unhygienic conditions, inadequate
refrigeration facility and poor storage conditions
What is Paneer?
Problem
• Paneer cheese is known to be contaminated with
Salmonella and E. coli O157:H7 at the point of retail
• The health risks of this contamination is unquantified
• We suspect that:
 The consumption of Paneer is responsible for a significant
burden of foodborne disease with size of production facility
as an important factor.
 The health risks associated with Paneer cheese increase as
a function of time and temperature of storage between
purchase and consumption.
 Increasing health risks correlate with consumer perceptions
of quality over time.
Hazard ID
Escherichia coli (EPEC)
• Morphology
– Gram –ve bacilli
• Pathology
– 106 Infectious dose
– Incubation time: 0.5-34hrs, mean 12.5hrs
– Acute Gastroenteritis
– ~17% attack rates (outbreaks in Southern Indian
towns) Kang et al, 2001
Escherichia coli O157:H7
• Produces Shiga-like toxin
• Pathology
– 10-102 infectious dose
– Incubation times: 3-8 days
– Acute gastroenteritis
– 5-10% of infections result in hemolytic uremic
syndrome (HUS)
– 8-14% (populations aged 11-30) (Belongia et al, 1991;
Gupta & Gupta, 2009)
NT Salmonella spp
• Morphology
– Gram –ve bacilli
• Pathology
– 103 infectious dose
– Incubation times: 12-120 hrs
– Salmonellosis
– 75.73% (Ref. population: Indian soldiers) (Vemula et al
2012)
Exposure Assessment
Exposure assessment
• Amongst three main routes of exposure only the
ingestion route can be accounted for in this case
• Exposure time: time of the purchase to 6 days
• The mean consumption for Paneer is estimated as
10 g/person-day
• We also addressed the growth of pathogen in
paneer under different storage temperatures
Exposure Framework Flow Chart
EPEC, E.
coli o157:H7
and
Salmonella
Bacteria
concentration
Storage
temperature
Daily ingestion
(10 gr/day)
Population of
India
Storage time
Unorganized
sectors-Retail
Organized
sectors-Retail
Fresh Paneer
Packaged
Paneer
Dose of
pathogen
received
Dose Response
E. coli O157:H7 Dose Response
• Exponential model developed from a pig
feeding trial, closest of available animal
models to humans
• 3 dose levels of the pathogen were evaluated
• Fecal shedding of the pathogen was used as a
proxy for infection
E. coli Generic Dose Response
• Beta-Poisson model developed from several
human studies in milk, 15 doses evaluated
• Measured mild to severe diarrhea in humans,
measure of illness, underestimates infection
• E. coli strains tested: Enteroinvasive E. coli
(EIEC) and Enterotoxigenic E. coli (ETEC)
• Excludes: non-pathogenic E. coli and Shiga
Toxin-producing E. coli (STEC) strains
Salmonella Dose Response
• Beta-Poisson model developed from a 16 dose
eggnog dose-response study of humans
• Positive fecal cultures as a proxy for infection
• Salmonella enterica subspecies enterica
serotype Anatum, our data not serotyped
• Salmonella Anatum is a commonly reported
bovine Salmonella serotype associated with
food products
Risk Characterization
Risk of Infection vs. Temp & Time
Relative Risk (packaged v. loose)
Statistical Significance of Relative Risk
Uncertainty of Risk Estimates (E. coli)
Sensitivity of Risk Estimates (E. coli)
Risk management
Implementation of microbiological criteria (MC)
 Current MC:
E. coli
Current MC
MC1
MC2
n
2
5
10
m
Absence in 4g
Absence in 4g
Absence in 4g
c
0
0
0
Salmonella
Current MC
MC1
MC2
n
2
5
10
m
Absence in 25g
Absence in 25g
Absence in 25g
c
0
0
0
*n is the number of samples to be tested from the batch/ lot, m is microbiological limit, c is
the maximum allowable number of samples exceed the limit.
 Modeled using ICMSF sampling tools
Reduced shelf life
 Reduce shelf life from up to 6 days to up to 4 days
 Modeled by truncate the distribution at max 96 hrs.
Risk management
Comparison of predicted annual cases related to E. coli and paneer
Name
Mean
Median
%Risk reduction
Baseline
694,736
52,282
N/A
Current MC
5,517
144
99.2%
MC1
1,460
106
99.8%
MC2
980
86
99.9%
Shelf Life
611,995
50,196
11.9%
Comparison of Annual Cases related to Paneer and
E. coli @4°C
1.0
0.5
Baseline
Current MC
0.3
MC1
MC2
ShelfLife
Annual cases in log scale
9
7
5
3
1
0.0
-1
Cumulative probability
0.8
Comparison of Annual Cases related to Paneer and
E. coli @24°C
Cumulative probability
1.0
0.8
0.5
Baseline
Current MC
0.3
MC1
MC2
ShelfLife
9
10
Annual cases in log scale
8
7
6
5
4
3
2
0.0
Risk management
Cost benefit analysis of alternative MCs
comparing to current MC
• Additional cost needed
• Illness cost reduced
MC1
4057
Illness cost
reduced
(USD)
5,415,634
MC2
4537
6,056,793
Reduced cases
Percent rejection Rejection cost
%
(USD)
Total cost
(USD)
0.07
24,272,500
18,856,866
0.18
62,415,000
56,358,207
• Conclusion: alternative MCs not cost effective comparing to
current MC
Risk Communication
Questions?
References
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Chandan RC. (2007). Manufacturing of paneer. In: Gupta, S (ed.) Dairy India. Diary India Yearbook, New Delhi,
p 411.
DuPont HL, Formal SB, Hornick RB, Snyder MJ, Libonati JP, Sheahan DG, LaBrec EH, and Kalas JP. 1971.
Pathogenesis of Escherichia coli diarrhea. The New England Journal of Medicine 285(1):1-9
Graham DY, Estes MK and Gentry LO. 1983. Double-blind comparison of bismuth subsalicylate and placebo in
the prevention and treatment of enterotoxigenic Escherichia coli-induced diarrhea in volunteers.
Gastroenterology 85(5):1017-1022.
Gupta SN and N Gupta. 2009. Outbreak of gastroenteritis in Tibetan Transit School, Dharamshala, Himachal,
Pradesh, India, 2006. Indian J Community Med 34(2): 97-101
Haas CN, Rose JB and Gerba CP. 1999. Quantitative Microbial Risk Assessment. John Wiley & Sons, Inc.
Kang G, Ramakrishna BS, Daniel J, Mathan M and VI Mathan. 2001. Epidemiological and laboratory
investigations of outbreaks of diarrhoea in rural South India: implications for control of disease. Epidemiol.
Infection 127(1): 107-112
Khan SW and MA Pal. (2011). Paneer Production: A review. J Food Science Technol 48(6): 645-660
Kumar S, Rai DC, Niranjan K, and Bhat ZF. 2011. Paneer- An Indian soft cheese variant: a review. J Food Sci
Technol. DOI 10.1007/s13197-011-0567-x (Published online).
Rao KVSS, Zanjad PN, and Mathur BN (1992) Paneer technology—A review. Indian J Dairy Sci 45:281–291.
Ryan KJ and Ray CG (Eds.). 2004. Sherris Medical Microbiology: An Introduction to Infectious Disease. (Fourth
Edition. ed.). Published by McGraw-Hill (New York).
Shrivastava, S. and Goyal, G. (2007). Preparation of paneer—A Review. Indian J Dairy Sci., 60(6): 377–388.
Singh, S.P. and Singh, K.P. (2000). Quality of market Paneer in Agra City. J. Dairying Foods Home Sci. 19(1): 3438