WHO Initiative to Estimate the Global Burden of Foodborne Diseases

Global Health Metrics and Evaluation Conference, SeattleJune 17-19, 2013

WHO Initiative to Estimate the Global Burden of Foodborne Diseases | June 17, 2013

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Estimating the Global Burden of Foodborne Diseases …… has not been done before… is complex… requires considerable resources

because …

… many different hazards can be transmitted by food… most can also be transmitted by other pathways… contamination occurs at many different points in the chain… they cause very diverse health outcomes… with different duration, severity and mortality

WHO Initiative to Estimate the Global Burden of Foodborne Diseases | June 17, 2013

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Why Estimate Global Burden?

2006 Expert Consultation: WHO

to lead efforts & appoint Foodborne

Disease Burden Epidemiology

Reference Group (FERG)

World Health Assembly 63, 2010 - Food Safety Resolution

Member States urged to:Improve evidence baseReduce burden

DG WHO urged to:Support country-based

assessmentsMonitor & report burden

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FERG Objectives• To provide epidemiological estimates on the global burden of all

relevant foodborne diseases (according to age, sex and WHO regions)

• To assist WHO to strengthen the capacity of countries to conduct burden of foodborne diseases and policy context studies

• To assist WHO in bridging the gap between collection of scientific evidence and food safety policy making

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FERG Structure

WHO Initiative to Estimate the Global Burden of Foodborne Diseases | June 17, 2013

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How does FERG work?● Annual meetings

– Planning and evaluation– Interaction between task forces– Interaction with stakeholders

● Task Force meetings– Physical meetings when necessary– Teleconferences

● Engagement with the scientific community– Commissioning of work (systematic reviews, data collection,

expert elicitation)– Presentation at scientific meetings

● Engagement with countries– Data collection (country burden studies)– Policy interface

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Hazards included in FERG estimates● Diarrheal diseases by Salmonella enterica (including invasive

salmonellosis), Shigella spp., Vibrio cholerae, EPEC, ETEC, STEC, Campylobacter spp., norovirus, Cryptosporidium spp., Entamoeba spp., Giardia spp., and unspecified agents

● Salmonella (para)typhi, Mycobacterium bovis, Brucella spp., ● Listeria monocytogenes, Hepatitis A virus● Intoxications by Clostridium perfringens, Clostridium botulinum,

Bacillus cereus, Staphylococcus aureus● Chronorchis spp., Opisthorchis spp., Fascioloa spp.● Echinococcus multilocularis, E. granulosis, Trichinella spp.● Toxoplasma gondii● Arsenic, Cadmium, Lead, Methylmercury● Aflatoxin, Cyanogenic glycosides, Peanut allergens● Dioxins

WHO Initiative to Estimate the Global Burden of Foodborne Diseases | June 17, 2013

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● 5 billion episodes per year, of which 3.2 billion in SEARO

● Average incidence rate 0.5/yr, similar for all regions except EMRO (0.9/yr)

● 1.2 million deaths per year in SEARO and AFRO

● Approx. 6% of all deaths in these regions

● Estimate for SEARO 6-fold higher than previously published

● Compare with 1.1 million deaths in children < 5 years in these two regions (approx. 15% of all deaths)

Fischer Walker CL, Black RE. Epidemiol Inf 2010;138:1215-1226

Diarrhea morbidity and mortalityin children ≥ 5 years and adults

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The global burden of neurocysticercosis● Neurocysticercosis is caused by

Taenia solium (pigs)● Wide variation in the prevalence of

NCC globally– 9% in Mexico, no symptoms– Hospitalisation 0.3-1.5 per

100,000 pyr in USA● 30% of patients with epilepsy have

NCC (Latin America, Sub-Saharan Africa, South-East Asia)

● Global burden of epilepsy is 6.2 million DALYs

Ndimubanzi PC et al. PLoS Negl Trop Dis 2010;4(11):e870

Global burden of aflatoxin

● 25,200-155,000 aflatoxin-induced liver cancer cases/yr● ~5-30% of all hepatocellular carcinoma cases

10 Liu Y, Wu F. (2010). Environ Health Perspect 118:818-824.

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Source Attribution

●Determine for each hazard (or specific groups of hazards) the proportion of the disease burden that is attributable to food

●Identify – and if possible quantify - the responsible reservoirs and/or food commodities leading to illness

●Food attribution at the point-of-exposure; specific food source attribution at the point-of-entry into household/food setting

Food Specific food sources

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Current approaches taken by FERG for source attribution● An assessment of all available methods has been performed, proposing SA methods for

all prioritised hazards that are not (almost) 100% originating from a single food source/reservoir

● For estimating the overall proportion foodborne, structured expert elicitation is assessed to be the only option for the vast majority of hazards, since

– Other methods estimate the proportion attributed to specific foods or reservoirs, but not the total

– The inevitable “unknowns” makes simple summation impossible

● For estimating the contribution from specific sources (or sub-pathways) within the pathway food, different methods including outbreak data and expert elicitation will be applied

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Piecing it all together: the Computational Task Force

WHO Initiative to Estimate the Global Burden of Foodborne Diseases | June 17, 2013

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FERG Country Studies Task Force● Task Force activity

– Development of burden of foodborne disease protocols and other tools to support individual country studies

– Policy situation analysis and knowledge translation/risk communication tools to support the use of burden of disease data in setting policy

– On-going technical support during individual country studies● Longer term goal

– Evaluation of protocols, making necessary revisions, towards a finalised user friendly suite of training and support tools

– Support of additional national burden of foodborne disease and situation analysis studies

● Following an application process in 2010, four pilot studies started in late 2011: Japan, Thailand, Uganda, Albania

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Conclusions● FERG has an ambitious agenda● The Initiative continues to expand● First results have been published, more are well underway● Attribution is a crucial, yet difficult component● Final results are expected to be published in 2014 ● Data gaps and uncertainties will remain

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Thanks to …● Amy Cawthorne, Fred Angulo, David Bellinger, Tim Corrigan,

Alejandro Cravioto, Herman Gibb, Tine Hald, John Ehiri, Martyn Kirk, Rob Lake, Nicolas Praet, Niko Speybroeck, Nilanthi de Silva, Claudia Stein, Paul Torgerson, Tanja Kuchenmüller

● Other members of the Foodborne Disease Burden Epidemiology Reference Group (FERG)

● Resource advisers● Commissioned scientists● Sponsors

● More information: http://www.who.int/foodsafety/foodborne_disease/ferg/en/index7.html

WHO Initiative to Estimate the Global Burden of Foodborne Diseases | June 17, 2013