Counting the global burden of foodborne disease

Foodborne diseases  include diarrhea due to foodborne pathogens, peanut allergies, poisoning from chemical contamination and emergent diseases such as avian ‘flu and BSE.  Foodborne illnesses cause many deaths annually all over the world.  But you may be surprised to find that the global burden of disease attributable to foodborne illness,  which is perhaps the most basic information needed to push forward research and action on foodborne illness,  is not known.

Why is there such an apparent lack of interest in documenting the scope of illnesses that affect people from all countries? One reason may be a common misconception that foodborne diseases are mild and self-limiting. A second and very important reason is that it’s often incredibly difficult to attribute foodborne illnesses and deaths to a specific foodstuff. And a third reason is that there is no well-heeled funder providing the impetus and cash to tackle foodborne illness, unlike other global problems such as HIV, malaria and TB.

In 2007, the WHO launched an international initiative to tackle foodborne disease. The WHO Initiative to Estimate the Global Burden of Foodborne Diseases aims to quantify how many people die from, or are affected by, all major foodborne causes each year.

The FERG (Foodborne Disease Burden Epidemiology Reference Group) initiative, led by Claudia Stein and Jorgen Schlundt from the WHO,  aims to set the problem of foodborne illness in context. At a recent meeting  at the WHO headquarters in Geneva (29-30th November),  Dr. Schlundt outlined the vicious circle in many developing countries that people get caught up in. Food is scarce so any food available is consumed, but that food is often unsafe, resulting in (usually) diarrheal disease. Diarrhea means that not only are foodstuffs underutilized but that resistance to pathogens is lowered, meaning that another bout of foodborne illness is even more likely.  He asserted that the only way to break the cycle of foodborne illness is through evidence-based policies to ensure that those who produce and prepare food provide food that is uncontaminated, either by chemicals or by pathogens. But the task of estimating the burden of foodborne disease is not straightforward.

FERG has commissioned research seeking to quantify burdens of different foodborne diseases. Early reports were presented at the meeting  and revealed the shocking level of the problem. A systematic review by Christa Fischer-Walker and Robert Black from Johns Hopkins School of Public Health in the US  revealed that there are a whopping 5 billion episodes of diarrhea in children aged > 5 annually, with 3.2 billion cases in South-East Asia. Specific inspection of papers reporting deaths revealed that there were more than 1.15 million estimated deaths from diarrhea in South East Asia and Africa each year in children >5 — this is almost a million more deaths than was previously estimated.  The paucity of data was laid bare by these preliminary results, with  no data for China, Latin America, the Middle East. Pathogens in the spotlight in these systematic reviews were the usual suspects, including E. coli, Shigella,  Vibrio cholerae, Campylobacter and Salmonella. This is not a burden solely borne by those living in poverty — 455 million episodes of diarrhea each year in the Americas and 419 million episodes each year in Europe.  The data are so limited that these global estimates are virtually bound to underreport the problem.

According to Martyn Kirk, chair of the FERG Enteric Diseases Task Force, who presented the results, “These estimates highlight the significant burden of diarrheal diseases in adolescents and adults in the developing world.”

Why should we care? Deaths from foodborne disease are likely to be high but the burden of disease also places a significant burden on economies. FERG plans to collect and summarise existing scientific data on foodborne disease and mortality into a global atlas. It will also train people from developing countries and help them conduct their own national studies to estimate and monitor the burden of disease from unsafe food.

We hope that the significant amount of information generated in assessing disease burden and attempting to attribute diseases to specific food sources, and moreover work that contributes towards changes in policies regarding food safety, are available to all in the public domain. At PLoS Medicine, we give the highest priority to publishing studies that advance human health in those areas that have the highest burden of disease, as we stated in a recent editorial about the scope of the journal. So we’ll continue to monitor this project with great interest.