Salmonella surveillance: a global survey of public health serotyping.

To better understand the global epidemiology of salmonellosis and the national surveillance programmes used for salmonella infections in humans, we conducted a global survey of the 191 WHO Member States. We gathered information on the total number of salmonella isolates serotyped, and the 15 most commonly isolated serotypes from humans in 1990 and 1995. Of the 104 countries that responded, 76 (73.1%) conducted public health surveillance for salmonella and 69 of these (90.8%) conducted serotyping as part of the surveillance. Fifty-nine countries (56.7% of those responding) provided information about the most commonly isolated serotypes in 1995. Three serotypes, Enteritidis, Typhimurium and Typhi accounted for 76.1% of all isolates reported in 1995. One of these three was the most common serotype identified in 93.2% of countries reporting data for that year. In 1995, Enteritidis was the most frequently isolated serotype in 35 countries, followed by Typhi (12 countries) and Typhimurium (8 countries). The global pandemic of Salmonella Enteritidis continued to expand. The mean national proportion of all salmonella isolates that were Enteritidis increased globally from 25.6% in 1990 to 36.3% in 1995. Serotyping is a frequently used component of a public health response to the global challenge of salmonellosis. Support for serotyping as part of national salmonella surveillance, and for rapid international communication of the results via a new WHO electronic website will help target future prevention strategies.

Foodborne disease control: a transnational challenge.

In the globalized political economy of the late 20th century, increasing social, political, and economic interdependence is occurring as a result of the rapid movement of people, images, values, and financial transactions across national borders. Another consequence of the increase in transnational trade, travel, and migration is the greater risk of cross-border transmission of infectious diseases. As the world becomes more interconnected, diseases spread more rapidly and effectively. With more than one million people crossing international borders every day, and with the globalization of food production, manufacturing, and marketing, the risk of infectious disease transmission is greater. Economic globalization has also increased the need for governmental budget austerity, and consequent national preparedness has been eroded. The emergence of new infectious diseases, as well as the reemergence of old ones, thus represents a crucial transnational policy issue. These problems cannot be resolved by national governments alone; they require international cooperation. This article analyzes the role of foodborne disease surveillance programs, nationally and internationally, in the control of foodborne diseases.

Global estimation of foodborne diseases.

Foodborne diseases are one of the most widespread health problems, but because of weaknesses in foodborne disease surveillance and variation in reporting systems between countries, it is difficult to make an estimation of their true incidence. This paper describes the constraints in the collection of information on the incidence and/or prevalence of foodborne diseases, including investigation and reporting at national and international levels. It also makes an attempt to semiquantify the occurrence of foodborne diseases of microbial and parasitical origin in different regions of the world.

Surveillance of foodborne diseases: what are the options?

Epidemiological data are needed for a variety of reasons, namely, informing public health authorities about the nature and magnitude of foodborne illnesses and their epidemiology, for the early detection of foodborne disease outbreaks, and for the planning, implementation and evaluation of food safety programmes. Thus, epidemiological surveillance of foodborne diseases is fundamental to any food safety programme. Various methods of foodborne surveillance may be utilized: (i) records for registration of deaths and hospital discharges; (ii) disease notification, (iii) sentinel surveillance, (iv) laboratory surveillance, (v) outbreak investigation and (vi) epidemiological research. This article reviews each method, its advantages and disadvantages, and its relevance for meeting the various objectives and needs.

Foodborne salmonellosis.

Foodborne diseases caused by non-typhoid Salmonella are a very important public health problem and an economic burden in many parts of the world. Salmonellosis data from the WHO Global Databank on Foodborne Disease, from the literature and from the WHO Surveillance Programme in Europe were reviewed for the years 1985-1995, showing an apparent increase in the incidence of salmonellosis in many parts of the world. In industrialized countries, this increase may be due to the emergence and increase of S. enteritidis and S. typhimurium DT104. In order to reduce the incidence of human foodborne salmonellosis, measures should be taken simultaneously during the production, processing, distribution, retail marketing and handling/preparation of food to prevent the introduction of Salmonella and its multiplication. These control measures need to be supported by effective foodborne disease surveillance programmes which make it possible to recognize and investigate outbreaks and emerging pathogens, and to assess the need for and evaluate interventions by monitoring longer term trends.

The role of food in the epidemiology of cholera.

Cholera is an acute dehydrating diarrhoeal disease, traditionally caused by vibrio cholerae O1, and also more recently by V. cholerae O139 (Bengal). Traditionally, water was recognized as the primary vehicle for transmission of cholera, but in the past 30 years, outbreaks of cholera associated with eating contaminated food have demonstrated that food also plays an important role, although in many instances water is the source of contamination of foods. Most commonly associated with cholera is seafood, both molluscan shellfish and crustaceans. Seafood may be contaminated in its natural environment or during preparation. Other food items associated with outbreaks are fruit and vegetables, meat, cooked grains, etc. Vegetables are usually contaminated by contact with sewage in soil and fruits when injected with contaminated water to increase weight and turgor. Food items initially free from V. cholerae organism may become contaminated when mixed with water, or other contaminated food, or through handling by infected persons who have not observed proper hygiene. Refrigeration, freezing, alkaline pH, high concentration of carbohydrate, humidity and absence of competing flora enhance the survival of V. cholerae in food. Survival of V. cholerae is shorter in food with acidic pH. Foodborne cholera can be averted by the hygienic preparation of food and its consumption. However, since the vehicles of transmission vary markedly from place to place, being affected by local customs and practices, selected control and preventive measures that are most important locally must be implemented. To this end, application of the Hazard Analysis and Critical Control Point system to food preparation is essential in order to identify the practices which may present a risk. Restrictions on importation of foods which do not present a risk of being contaminated from areas where cholera is endemic is not warranted.

Food fermentation: a safety and nutritional assessment. Joint FAO/WHO Workshop on Assessment of Fermentation as a Household Technology for Improving Food Safety.

An assessment of the food-safety and nutritional aspects of lactic acid fermentation for the preparation of weaning food at the household level was carried out during a Joint FAO/WHO Workshop held in Pretoria, South Africa, in December 1995. In particular, lactic acid fermentation was evaluated as a part of food preparation processes involving other operations such as soaking, cooking, and the germination of cereal grains. The use of germinated cereals is of particular interest since they can be used to prepare semi-liquid porridges of high nutrient density. After reviewing the present state of knowledge concerning the antimicrobial effects of the lactic acid in fermented foods, and the nutritional benefits of fermentation and the use of germinated cereals, the Workshop made an inventory of gaps in current knowledge and priorities for further research. High priority areas for research include the following: the effect of lactic acid fermentation on viruses, parasites, certain bacteria, and mycotoxins; certain physiological and nutritional effects of the consumption of fermented foods; the characterization and optimization of fermentation processes and the development of appropriate fermentation starters; and risk mitigation using the Hazard Analysis Critical Control Point system, the health education of food handlers, and efforts to change the consumer perception of fermented foods.

Alimentos de destete contaminados: un importante factor de riesgo de diarrea y malnutrición asociada / Contaminated weaning food: a major risk factor for diarrhoea and associated malnutrition

Las infecciones y la malnutrición asociada son la causa de una proporción importante de los 13 millones de defunciones de lactantes y niños menores de 5 años que cada año se producen en el mundo. Entre las enfermedades de los lactantes y niños pequeños las infecciones respiratorias ocupan el primer lugar, seguidas por las enfermedades diarreicas, que son las más perjudiciales para el crecimiento. Las causas de las enfermedades diarreicas se han atribuido tradicionalmente a problemas de abastecimiento de agua y saneamiento. Para prevenir esas enfermedades, los gobiernos y las organizaciones no gubernamentales se han centrado y a veces se han limitado a mejorar el abastecimiento de agua y el saneamiento, así como a fomentar y proteger la lactancia materna. A partir de diversos trabajos publicados, este artículo de revisión muestra que los alimentos de destete preparados en condiciones no higiénicas muchas veces están contaminados por grandes cantidades de gérmenes patógenos y son por ello una de las causas principales de enfermedad diarreica y malnutrición asociada. De los datos presentados se deduce que las direcciones de trabajo actuales no basta para prevenir las enfermedades diarreicas. Debe considerarse prioritaria la educación de las madres en los principios de inocuidad de los alimentos, en particular de los alimentos de destete. En todos los programas nacionales de alimentación infantil o de alimentación y nutrición deberían integrarse programas educativos basados en el análisis del riesgo potencial y en la determinación de puntos críticos de control, teniendo también en cuenta los factores socioculturales

Contaminated food, a hazard for the very young.

Contaminated food is responsible for much diarrhoeal disease in young children, yet the education of mothers and care-givers about the preparation of food under hygienic conditions tends to be neglected.

PIP: Breast milk is no longer sufficient to meet the nutritional requirements of infants aged 4-6 months; thus, during weaning, complimentary foods should be introduced gradually. At this time, infants are at increased risk of getting diarrhea from food-borne pathogens resulting in reduced food intake and loss of nutrients through vomiting and fever. Diminished immunological resistance to infections causes as estimated 13 million fatalities a year among children under 5 years of age as a result of infectious diseases and malnutrition. In developing countries, preparation of weaning foods under unhygienic conditions causes up to 70% of diarrheal cases. Pathogenic strains of Escherichia coli account for up to 25% of diarrhea episodes. The sources of food contamination are night soil, polluted water, files and other pests, domestic animals, dirty utensils and pots, unwashed hands, and dust. Pathogenic bacteria can multiply if the food is prepared several hours before consumption and stored at temperatures favoring the growth of microorganisms and/or production of toxins. Insufficient cooking or reheating can also facilitate bacterial growth. Sociocultural and economic factors contribute to risks, such as short supply of food; maternal ignorance about the link between diarrhea and improper food handling; unsafe water supplies and lack of sanitation with increased risk of food contamination; shortage of fuel for cooking and lack of refrigeration; and insufficient time for food preparation. The World Health Organization Golden Rules for Safe Food Preparation need to be observed. Food should be thoroughly cooked and fed to infants once it is cool enough; food should not be stored where there are no facilities for storage below 10 degrees Celsius or for keeping food at or above 60 degrees Celsius. Mothers should be advised about food safety within the framework of educational programs.

Alimentos de destete contaminados: un importante factor de riesgo de diarrea y malnutrición asociada / Contaminated weaning food: a major risk factor for diarrhoea and associated malnutrition

Las infecciones y la malnutrición asociada son la causa de una proporción importante de los 13 millones de defunciones de lactantes y niños menores de 5 años que cada año se producen en el mundo. Entre las enfermedades de los lactantes y niños pequeños las infecciones respiratorias ocupan el primer lugar, seguidas por las enfermedades diarreicas, que son las más perjudiciales para el crecimiento. Las causas de las enfermedades diarreicas se han atribuido tradicionalmente a problemas de abastecimiento de agua y saneamiento. Para prevenir esas enfermedades, los gobiernos y las organizaciones no gubernamentales se han centrado y a veces se han limitado a mejorar el abastecimiento de agua y el saneamiento, así como a fomentar y proteger la lactancia materna. A partir de diversos trabajos publicados, este artículo de revisión muestra que los alimentos de destete preparados en condiciones no higiénicas muchas veces están contaminados por grandes cantidades de gérmenes patógenos y son por ello una de las causas principales de enfermedad diarreica y malnutrición asociada. De los datos presentados se deduce que las direcciones de trabajo actuales no basta para prevenir las enfermedades diarreicas. Debe considerarse prioritaria la educación de las madres en los principios de inocuidad de los alimentos, en particular de los alimentos de destete. En todos los programas nacionales de alimentación infantil o de alimentación y nutrición deberían integrarse programas educativos basados en el análisis del riesgo potencial y en la determinación de puntos críticos de control, teniendo también en cuenta los factores socioculturales

Publicado en inglés en: Bull. WHO. Vol. 71(1), 1993

Contaminated weaning food: a major risk factor for diarrhoea and associated malnutrition.

Infections and the malnutrition associated with them are responsible for a significant proportion of the 13 million deaths among infants and children under 5 years of age worldwide each year. After respiratory infections, diarrhoeal diseases are the commonest illnesses and have the greatest negative impact upon the growth of infants and young children. The causes of diarrhoeal diseases have traditionally been ascribed to water supply and sanitation. In attempts to prevent such diseases, efforts by governments and nongovernmental organizations have been focused on and sometimes limited to improving water supply and sanitation as well as promoting and protecting breast-feeding. Based on studies reported in the literature, this review article demonstrates that weaning foods prepared under unhygienic conditions are frequently heavily contaminated with pathogens and thus are a major factor in the cause of diarrhoeal diseases and associated malnutrition. In the light of the evidence presented, it appears that current efforts are not sufficient to prevent diarrhoeal diseases: education of mothers in food safety principles, particularly weaning food, must also receive high priority. Educational programmes based on the hazard-analysis-critical-control-point approach, taking into consideration also sociocultural factors, should be integrated into all national infant feeding or food and nutrition programmes.

PIP: Even though contaminated foods are responsible for up to 70% of diarrheal episodes, efforts to prevent diarrheal diseases often overlook food safety. Food safety is at least as important as breast feeding or providing a safe water supply and sanitation services. In developing countries, weaning foods are often prepared in an unhygienic manner. Thus, the weaning age is an especially dangerous time for infants since they are exposed to infective doses of foodborne pathogens. Infections caused by pathogenic Escherichia coli is probably responsible for as much as 25% of all diarrheal episodes in developing countries. E coli is often linked to weaning foods. Other significant microbial infections causing diarrhea include shigellosis and cholera. Rotavirus most frequently attacks 6-24 month olds and causes 20% of all diarrheal deaths among those under 5 years old. Foodborne infections can have dangerous and longterm effects, especially on nutritional status. In fact, the resistance of infants suffering from nutritional deficiencies is suppressed, leaving them wide open to infectious diseases, particularly those causing diarrhea, which further reduces their ability to fight disease. They then become progressively more malnourished. Food contamination sources include unclean hands, feces, polluted water, flies, pests, domestic animals, unclean utensils and pots, and an unsanitary environment. Cross-contamination during food preparation is also responsible, e.g., contact between raw and cooked foods. Beliefs and practices, ignorance, taboos, poverty, insufficient food, social infrastructure, and shortage of fuel and time often make it more difficult to assure food safety. Food safety could reduce hospital costs since diarrhea is the leading reason for hospitalizations among children. Food safety education for mothers in primary health care and infant feeding programs is the most important intervention in promoting the health and nutritional status of infants and children.