Preventive Strategy Against Infectious Diarrhea—A Holistic Approach

Abstract

Some national or international public health policies report on infectious diarrheal disease morbidity and mortality without mentioning, or even considering, food as a risk factor. As a consequence, data on the relative role of food in the epidemiology of such diseases are scarce and preventive measures do not adequately include food safety considerations. The purpose of this commentary is to highlight that for effective prevention of infectious diarrhea a holistic approach to hygiene, including both food and water safety interventions, is required. Acute infectious diarrhea continues to have a terrible public health cost. At present, globally, some 1.3–1.5 million children (<5 years) deaths, or nearly 1 in 5 child deaths, are associated with diarrhea. Although this is a remarkable decrease from the 4.6 million of the 1980s, infectious diarrhea remains the second leading cause of death in children, after respiratory diseases.1Black R.E. Cousens S. Johnson H.L. et al.Global, regional, and national causes of child mortality in 2008: a systematic analysis.Lancet. 2010; 375: 1969-1987Abstract Full Text Full Text PDF PubMed Scopus (2040) Google Scholar, 2UNICEF/WHODiarrhoea: why children are still dying and what can be done?. World Health Organization, Geneva2009Google Scholar According to the 2004 estimates, worldwide an estimated 4.6 billion episodes of diarrhea occur per year for all ages and 2.2 million die as a result.3World Health OrganizationGlobal burden of disease estimates, 2004 update. World Health Organization, Geneva2008Google Scholar Despite reduced mortality, morbidity has not substantially declined in the last 30 years.4Käferstein F.K. Food safety: the fourth pillar in the strategy to prevent infant diarrhea.Bull World Health Organ. 2003; 81: 842-843PubMed Google Scholar In the developing regions of the world, on average, children under the age of 5 continue to suffer 3.2 episodes of diarrhea per year.4Käferstein F.K. Food safety: the fourth pillar in the strategy to prevent infant diarrhea.Bull World Health Organ. 2003; 81: 842-843PubMed Google Scholar, 5Kosek M. Bern C. Guerrant R.L. The global burden of diarrhoeal disease, as estimated from studies published between 1992 and 2000.Bull World Health Organ. 2003; 81: 197-204PubMed Google Scholar, 6Motarjemi Y. Kaferstein F. Moy G. et al.Contaminated weaning food: a major risk factor for diarrhea and associated malnutrition.Bull World Health Organ. 1993; 71: 79-92PubMed Google Scholar Although the risk is greatest in low-income countries, particularly where the sanitary conditions are poor (eg, refugee camps, slums of urban areas), the problem is global, and even luxury travelers are not spared. Industrialized countries also report a relatively high incidence of illness. In the United States, the number of gastrointestinal infections is estimated to be 178 million cases per year. Of these 48 million cases (27%) are estimated to be foodborne, and result in 128,000 hospitalizations and 3000 deaths.7US Centers for Disease Control and PreventionCDC Estimates of foodborne illness in the United States.http://www.cdc.gov/foodborneburden/2011-foodborne-estimates.htmlGoogle Scholar A similar figure is also reported from the Netherlands. Out of 1.8 million cases of gastroenteritis caused by 14 infectious agents, >30% (680,000 cases) are proven to be foodborne.8Havelaar A.H. Haagsma J.A. Mangen M.J.J. et al.Disease burden of foodborne pathogens in The Netherlands, 2009.Intl J Food Microbiol. 2012; 156: 231-238Crossref PubMed Scopus (260) Google Scholar The scale of the outbreaks of acute infectious diarrhea, often foodborne, can be impressive, as demonstrated in last year's outbreaks of Shiga-toxin producing enteroaggregative Escherichia coli O104:H4 in Germany and France associated with fenugreek seeds imported from Egypt, and in several deadly outbreaks in the United States. For instance, from July to October 2011 an outbreak of Listeria monocytogens associated with cantaloupe affected some 147 persons and caused ≥30 deaths. A plethora of pathogens, including bacteria, viruses, and parasites, are associated with infectious diarrhea. Walker et al9Walker C.L.F. Sack D. Black R.E. Etiology of diarrhoea in older children, adolescents and adults: a systematic review.PLoS Neglected Tropical Diseases. 2010; 4: e768Crossref PubMed Scopus (101) Google Scholar provide a systematic review of the major pathogens involved. The list grows as new pathogens emerge. It is recognized that diarrhea can lead to severe and life-threatening illness in the very young; however, diarrheal illnesses in adults are often perceived as a benign and self-limiting inconvenience. Yet, acute infectious diarrhea can be deadly for vulnerable groups, such as immunosenescent older adults, persons immunocompromised by underlying illnesses, medication or medical interventions, or by malnutrition. The sequelae of infectious diarrhea are also a little-recognized public health problem. These include irritable bowel syndrome, arthritis, Reiter syndrome, and Guillain-Barré syndrome. Repeated bouts of diarrhea in the initial 2 years of life are associated with both mental and growth stunting and can lead to severe malnutrition, which itself is another major cause of mortality. Despite recent advances in evidence-based policymaking, and despite the known public health burden posed by diarrheal illnesses, present policies remain based on old paradigms and misconceptions. Overcoming these is essential for development of an efficient prevention strategy required to reduce both mortality and morbidity. Many pathogens associated with infectious diarrhea are transmitted through the fecal–oral route, hence the importance of hygiene and sanitation to reduce the risk of person-to-person and waterborne transmission. However, equally important, but often forgotten, is the role of food as a vehicle for acute infectious diarrhea. Pathogens may contaminate food through diverse routes, including contaminated environment, manure used for fertilization, wastewater used for irrigation, animals from which the food is derived, infected food handlers—remember Typhoid Mary—poor hand hygiene, domestic animals and pests, and contaminated equipment and water used for preparation of food. Additionally, food being a favorable medium for bacterial growth, bacterial pathogens thrive in food and with even the least time–temperature abuse, can reach infective doses or produce toxins. With such plausible mechanisms, and as demonstrated by epidemiologic data, food is among the most important factors in transmitting diarrheal illnesses. Nevertheless, risks associated with food contamination and the need for improving food safety are frequently omitted from the strategies for the prevention of diarrheal illness by public health authorities and development agencies. This is illustrated by World Health Organization (WHO) and UNICEF policies, where the risk associated with food contamination is neglected and only mentioned in the context of humanitarian crises.2UNICEF/WHODiarrhoea: why children are still dying and what can be done?. World Health Organization, Geneva2009Google Scholar This unfortunate omission is echoed by other medical publications.10Moore S.R. Lima A.A. Guerrant R.L. Infection: preventing 5 million child deaths from diarrhea in the next 5 year.Nat Rev Gastroenterol Hepatol. 2011; 8: 363-364Crossref PubMed Scopus (15) Google Scholar, 11Walker C.L.F. Friberg I.K. Binkin N. et al.Scaling up diarrhea prevention and treatment interventions: a lives saved tool analysis.PLoS Med. 2011; 8: e1000428Crossref PubMed Scopus (60) Google Scholar Neglecting food contamination as a risk factor for diarrheal illness may be due to misinterpretation of data because non-experts consider outbreak data as a quantitative expression of food safety problems. In reality, outbreak data are only the tip of the iceberg and not indicative of the real magnitude of the problem; the real number of patients can be several hundred or thousand times higher than that expressed in documented outbreak-related data (Figure 1). With the industrialization of the food supply, many outbreaks associated with processed or manufactured food appear as sporadic cases, and therefore go undetected, unless the country benefits from a strong network of laboratory-based surveillance, such as that of the United States. Underreporting of foodborne illnesses can be significant. For instance in the study from The Netherlands, only about 1 in 20 persons suffering from gastroenteritis visited a general practitioner.8Havelaar A.H. Haagsma J.A. Mangen M.J.J. et al.Disease burden of foodborne pathogens in The Netherlands, 2009.Intl J Food Microbiol. 2012; 156: 231-238Crossref PubMed Scopus (260) Google Scholar Undoubtedly, the underreporting factor is substantially greater in developing countries. In countries with weak surveillance programs, the problem is greatest, as the lack of reports becomes a justification for an attitude that no action is required. Let us remember that absence of evidence is not necessarily evidence of absence. The high incidence of travelers' diarrhea in these countries is an indication of underlying food and water safety problems in these regions. For instance, reviews of foodborne illnesses associated with microbial contamination of fruits and vegetables report frequent outbreaks from the industrialized countries but rarely, if at all, are outbreaks in the developing countries mentioned. In a recent, worldwide review of some 70 outbreaks from 1995−2010 none of the reported outbreaks related to produce were from a developing country.12Soon J.M. Manning L. Davies W.P. et al.Fresh produce-associated outbreaks: a call for HACCP on farms?.Br Food J. 2012; 114: 553-597Crossref Scopus (29) Google Scholar Yet, from the illnesses associated with the Shiga-toxin producing enteroaggregative E. coli O104:H4 in Germany and France mentioned above, to give as an example, and the international travelers who develop diarrhea, we know that fruits and vegetables are contaminated and are thus a likely source of illness in these countries as well. Another misconception is that the management of infectious diarrhea has been considered to belong to the realm of public health, whereas food safety is associated with food regulation and food control agencies. Thus, the role of public health professionals in educating the general public, particularly at-risk groups, in food safety has received marginal attention, although health professionals are considered as the most trusted source of advice. Food safety is receiving little attention in medical and public health schools, not to mention primary and secondary schools where other health education topics such as AIDS, dental health, and nutrition are taught. To prevent infant diarrhea, the focus has been primarily on promoting breastfeeding. Although this should remain the highest priority, combining that with food safety education for the preparation of complementary family food would have positive bearings beyond 6 months of age.6Motarjemi Y. Kaferstein F. Moy G. et al.Contaminated weaning food: a major risk factor for diarrhea and associated malnutrition.Bull World Health Organ. 1993; 71: 79-92PubMed Google Scholar Worldwide, much of the recognition of food safety in the recent years has come from the trade and agriculture sectors. In many countries, instead of being at the forefront to ensure that human health is adequately considered in food safety standards and policies and playing a more prominent role in food safety, the health sector has adopted a passive approach. Often expressed is that in underdeveloped countries food security (food availability) is a greater problem than food or water safety, and compare the acceptability of the risk of eating and drinking contaminated food and water versus that of dying from starvation. This is a fair point to raise in the context of standard settings, because sometimes a slightly higher level of a hazard (often of a chemical nature) may not have a significant public health impact but may have great significance for food security, food price, and/or food export. For these very reasons, in the context of national or international standard setting work (Codex Alimentarius Commission refers), it is important also to consider the impact of food safety policies on food security, as well as the impact of food security on food safety policies. However, in the context of potentially lethal illnesses, such as acute diarrheal diseases, which even when not killing directly, are the underlying factors for malnutrition and other infections, in particular in children under the age of 5, the argument of food security versus food safety is misplaced, not to say unethical. With such a comparison, we would be arguing which mode of dying is more acceptable: Starvation, or dying of an acute diarrheal infection or food poisoning? The role of public health should be preserving the health of the population and using the available resources as efficiently as possible: Thus, the little food that a vulnerable population receives should bring them the nutrients that they need and not be the source of loss of nutrients, dehydration, and/or other illnesses. Moreover, omitting safety aspects from public health or agriculture policies in the developing countries on the ground that we should first ensure food availability would be accepting a double standard and opens the door for “dumping” food from industrialized to developing countries. At national and international levels, both food safety and food security should go hand in hand and should not be exclusive of each other. On the contrary, they have synergic effects as most technologies used for food preservation also promote safety, be it at the industrial level (eg, pasteurization, canning, drying, irradiation) or at the household level (eg, refrigeration, fermentation). Much of the food scarcity in the African continent results from spoilage and wastage of food rather than from insufficient production. Despite these comments, we should not undermine the role of poverty in food and/or waterborne illnesses. Clearly, if we analyze the situation of food safety in developing countries in depth, we find certain situations where poverty has been the root cause of diarrheal illnesses, or more broadly illnesses related to food contamination/food safety.6Motarjemi Y. Kaferstein F. Moy G. et al.Contaminated weaning food: a major risk factor for diarrhea and associated malnutrition.Bull World Health Organ. 1993; 71: 79-92PubMed Google Scholar For instance, there have been anecdotal reports of outbreaks of pesticide poisoning owing to consumption of seeds planned for planting, or staples heavily contaminated with toxigenic molds had been consumed, or for economic reasons food not being thrown away but kept as leftovers at room temperature. However, the worst aspect of poverty is that the poor have no access to clean water, sanitation, or equipment such as a refrigerator, or even enough fuel for proper cooking.6Motarjemi Y. Kaferstein F. Moy G. et al.Contaminated weaning food: a major risk factor for diarrhea and associated malnutrition.Bull World Health Organ. 1993; 71: 79-92PubMed Google Scholar However, these are extreme conditions of poverty as not all of the population in developing countries are in such exceptionally poor conditions where poverty alone would be the root cause of their illness. So often, a chain of other factors lead to food safety problems. The issue that is at the heart of this commentary is that health professionals are the start of this chain and should have a leading role in acknowledging that “food” is a major route of transmission of diarrheal illness and a potential risk factor. Unless this is known, acknowledged, and communicated by the health sector, there is little chance that food safety will be considered along with food security, and that data are collected on the problem and its prevention. The vicious cycle will continue with the lack of data being taken as a reason for omitting food safety in public health or agriculture policies. Policymakers and health professionals must realize that to achieve an efficient and cost-effective management of this problem, they need to recognize all risk factors and to implement an integrated, interdisciplinary approach. Where the various public health programs are promoting their own piecemeal interventions as “the key” to prevention, they will tend to undermine the synergistic effects that a concerted and integrated effort can otherwise achieve. The challenge is huge; improving hygiene, sanitation, safe water supply, nutrition, and food safety each require massive amounts of effort. However, so also are the stakes high. The present situation is far from satisfactory, let alone the future outlook. Climatic changes may result in increased infections in the animal population and in natural disasters that destroy the infrastructure of safe water supply. Emergence of drug resistant pathogens will add difficulty to treatment of infectious diarrhea. Increases in the population and a growing number of vulnerable individuals, urbanization, international travel, global trade in food and feed, changes in food production methods, and home preparation practices may contribute to increased problems. The trend in the developing countries to adopt the Western lifestyle, for example, mass production and ready-to-eat “take-away” food, without adequate infrastructure for managing food safety throughout its food chain, is particularly worrisome and calls for the attention of the public health institutions. It would be wrong to prescribe a specific organizational structure or measures at the international level; the situation in each country is different and any intervention and decision on priorities should be data driven. However, in view of the limited resources and the need for most effective use of these, a starting point for all public health authorities is to review their current intervention priorities and verify that their efforts adequately include food safety and that this is pursued in tandem with improvements in hygiene, sanitation, safe water supply, and nutrition. This also applies to development agencies that fund diarrheal disease control programs. Inclusion of food as route of transmission for diarrheal illnesses is essential if data on the relative role of food contamination are to be collected. Education is a central point of all interventions, be it through awareness campaigns (eg, WHO Five Keys to Safer Foods), training of health professionals on the job, and/or education of medical and public health students. In some countries, organizational changes may be required to strengthen interdisciplinary collaboration. For instance, surveillance and investigation of outbreaks should go hand in hand with regulatory and enforcement measures so that the feedback cycle of prevention, monitoring, and evaluation can lead to continuous improvement in public health. Naturally, the world public health authorities, such as the WHO and UNICEF, as the source of guidance should also recognize the benefits of an integrated strategy and support an interdisciplinary, multisector approach through their policy and field interventions. These comments evolved from discussions of the Steering Committee for the World Digestive Health Day 2011 (Enteric Infections: Prevention and Management; Clean Food, Clean Water, Clean Environment) sponsored by World Gastroenterology Organization.