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Foodborne Disease and Public Health: Summary of an Iranian–American Workshop 3 Selected Gastrointestinal Diseases in Iran and Their Investigation Moderators: Michael Doyle and Mohammad Mehdi Aslani A variety of organisms are known to be responsible for foodborne illness, and Iranian researchers have investigated many of them. During the session covered by this chapter, Mohammad Mehdi Aslani described the work of Iranian laboratories that address foodborne illness, Fereshteh Jafari provided an overview of the Research Department of Foodborne and Diarrheal Diseases, Maryam Sanaei discussed work on rotavirus in Iran, E. Nazemalhosseini Mojarad reported on an Iranian study of Entamoeba histolytica and E. dispar, and Leila Shokrzadeh addressed the distribution of Salmonella subspecies in Iran. The Research Center for Gastroenterology and Liver Diseases also has a keen interest in causes of gastrointestinal disease that may not be foodborne; in this vein, Hosein Dabiri Jaldebakhani described the research center’s investigations of Helicobacter pylori, and Mohammad Reza Zali described the burden of gastrointestinal disease in Iran. Key points from the discussion appear at the end of the chapter. CURRENT TECHNICAL AND SCIENTIFIC ASPECTS OF FOODBORNE DISEASE IN IRAN Presenter: Mohammad Mehdi Aslani Overview Related to Foodborne Illness Outbreaks In countries around the world, a goal of national health organizations is to protect the health of their countries’ populations and to reduce the
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Foodborne Disease and Public Health: Summary of an Iranian–American Workshop toll of infectious diseases, poisons, and chemical and radiation hazards. According to the World Health Organization and the Food and Agricultural Organization, illness caused by contaminated food is one of the world’s most widespread health problems. In 2006 there were 26 foodborne illness outbreaks reported in Iran, but, Aslani said, the extent of the problem is certainly much greater. The 26 reported outbreaks affected nearly 5,000 people and resulted in 11 deaths. The most commonly found causative agent was Eschericia coli (type unspecified); other identified causative agents were non-typhi Salmonella, S. typhi, Shigella, Staphylococcus aureus, Entamoeba histolytica, and rotavirus. Food production, processing, marketing, and distribution take many forms in Iran. Much of the food handling occurs locally, at the village level, where it is difficult, if not impossible, to implement inspections and other measures to prevent foodborne illness. On the other hand, large-scale food production and industrial food processing come under the purview of the Iranian government. Three ministries are involved in the inspection and control of such processes: the Ministry of Health and Medical Education, the Ministry of Agriculture, and the Ministry of Industry. Iranian Laboratories That Address Foodborne Illness Laboratories provide information that is important to the detection and prevention of foodborne disease. The primary means used to identify target organisms in Iran have been older methods that are both slow and labor-intensive. Molecular methods, such as polymerase chain reaction (PCR), are now used to some extent; but the establishment of PCR laboratories throughout the country will require a high financial investment by the government as well as the development of staff training programs, officially approved methods, and national standards. Moreover, PCR results are not definitive: for instance, showing that a toxin gene is present indicates the presence of bacteria but not necessarily the presence of a biologically active toxin. Ardalan listed several Iranian laboratories involved in the analysis of foodborne diseases, along with the activities that take place in each: Food and drug laboratories under the supervision of the Ministry of Health and Medical Education: diagnostic microbiology, virology, and other areas using traditional methods Institute Pasteur of Iran: the diagnosis of Enterobacteriaceae by traditional and molecular methods, the diagnosis and typing of Vibrio cholerae, and the use of molecular typing methods
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Foodborne Disease and Public Health: Summary of an Iranian–American Workshop Research Center for Gastroenterology and Liver Diseases: a reference laboratory for outbreak investigations, the diagnosis of Enterobacteriaceae by traditional and molecular methods, food sample preparation, and the culture and diagnosis of Campylobacter Iranian veterinary organization laboratories in the Ministry of Agriculture: responsibility for safety related to foods of animal origin Institute of Standards and Industrial Research (20 branches throughout the country): facilities for the physical, microbiological, and chemical analysis of food samples Ardalan called for national laboratories to be established for the study of foodborne pathogens, for the reporting and transport of isolates of specified pathogens to the national laboratories, and for the subtyping of isolates. He also suggested the establishment of both a national and international databank to store subtyping data of isolates of foodborne pathogenic bacteria. Studies Related to Shiga Toxin-Producing Escherichia coli Several studies have been conducted to investigate Shiga toxin-producing E. coli (STEC) in Iran (Aslani et al., 1998; Aslani and Bouzan, 2003). Of 2,008 fecal samples screened for STEC in the summer and autumn of 1997, fewer than 5 percent were STEC-positive. In rural areas, individuals carrying STEC were likely to be asymptomatic. Ardalan postulated that the lack of symptoms in people living in rural areas could be the result of contact with livestock and the drinking of unpasteurized milk, resulting in an immunity acquired over time. In urban areas, by contrast, investigators found a significant association between diarrhea and STEC. Children younger than 5 years of age were at the highest risk of infection. In other studies, fecal samples from cattle, beef samples, and raw milk samples were screened for STEC. About 20 percent of both the fecal samples and the meat samples were STEC-positive, while only 3 percent of the milk samples were. None of the isolates belonged to the O157:H7 serotype. THE RESEARCH DEPARTMENT OF FOODBORNE AND DIARRHEAL DISEASES Presenter: Fereshteh Jafari The Research Department of Foodborne and Diarrheal Diseases was established in 2000 under the auspices of the Research Center for Gastro-
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Foodborne Disease and Public Health: Summary of an Iranian–American Workshop enterology and Liver Diseases. Its goal is to better understand the epidemiology of foodborne diseases in Iran in order to provide authorities with information to improve the effectiveness of prevention measures. The department focuses on outbreak investigations, foodborne disease surveillance, the molecular typing of foodborne pathogens, and the microbial analysis of food samples. It also studies the antimicrobial susceptibilities of foodborne pathogens, the development of relevant microbial methods, and the determination of chronic sequellae of foodborne diseases. The functions of the Research Department of Foodborne and Diarrheal Diseases include the following: The isolation and identification of foodborne pathogens The serotyping and determination of antimicrobial susceptibility Finding patterns of foodborne pathogens using molecular techniques The preservation of isolated strains The maintenance of its culture collection Jafari showed slides listing many of the techniques used in the molecular laboratory, from the basic staining techniques to the more advanced molecular biology techniques. He also highlighted the interests and methods of the four reference laboratories for foodborne diseases: bacteriology, virology, pathology, and polymerase chain reaction (PCR) and molecular diagnostics. The Research Department of Foodborne and Diarrheal Diseases collaborates with the Health System Research Department, which was established in 2005, also within the Research Center for Gastroenterology and Liver Diseases. That department is responsible for collecting and transporting specimens to the Foodborne Laboratory. A goal of the Research Department of Foodborne and Diarrheal Diseases is to contribute to the control and reduction of foodborne diseases in the population. Part of the department’s strategy to achieve this goal is to control foodborne infections acquired at the community level and to control the quality of foods. The Research Department of Foodborne and Diarrheal Diseases is involved in several international collaborations. These include work with the Swedish Institute of Infectious Disease Control relating to the virulence of diarrheagenic E. coli; a project supported by the World Health Organization to investigate the prevalence of soil-transmitted helminthes infection in Tehran province; serving as a reference for a surveillance system; and work with other agencies on enteric bacterial infections and on microbiota in healthy people and in patients with colorectal cancer.
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Foodborne Disease and Public Health: Summary of an Iranian–American Workshop ROTAVIRUS Presenter: Maryam Sanaei1 Viral gastroenteritis is a virus-caused inflammation of the gastrointestinal tract, generally triggered by consuming food or water that is contaminated by viruses that cause vomiting or diarrhea. A large percentage of viral gastroenteritis is caused by a class of viruses called rotavirus. Human feces are the primary source of contamination with rotavirus; respiratory secretions are another source. Sanaei presented slides covering the morphology, genome, genotyping, classification, pathogenesis, epidemiology, laboratory methods for detection, and prevalence of rotaviruses in Iran. The predominant genotypes in Iran are G4 and G1. A study in the Research Department of Foodborne and Diarrheal Diseases looked extensively at the epidemiology of rotavirus infection and found very high rates of infection among infants and children younger than 2 years of age, with a peak incidence among children 7 to 12 months old. By that age, the passive immunity provided by the mother has decreased, and the children may be exposed through eating or drinking contaminated foods or beverages or by touching toys or other objects contaminated with rotavirus. Epidemics in Iran typically occur from November to April. In Tehran, Shiraz, and Banderabas, for example, the peak occurs in December; whereas in Mashhad and Tabriz it occurs in February. The peak time appears to vary with climatic factors such as temperature, rainfall, and humidity. PREVALENCE AND GENETIC DIVERSITY OF ENTAMOEBA HISTOLYTICA AND ENTAMOEBA DISPAR IN IRAN Presenter: Ehsan Nazemalhoseini Mojarad2 Entamoeba histolytica is a parasitic protozoa that is an important foodborne pathogen. In 2006 it was found to be the cause of one of the 26 foodborne illness outbreaks reported in Iran. Relatively little is known about the epidemiology of illnesses caused by this protozoa. Nor is it well understood why disease develops in only 5 percent to 10 percent of the people infected by these amoebas. Possible reasons include a spectrum 1 Sanaei acknowledged the contributions of Houtan Radpour, Reza Mohebi, and Mohammad Reza Zali. 2 Mojarad acknowledged the contributions of A. Haghighi, B. Kazemi, and Mohammad Reza Zali.
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Foodborne Disease and Public Health: Summary of an Iranian–American Workshop of virulence among the E. hystolytica strains and variability in the host immune response against amoebic invasion. In a study carried out over the past several years, Iranian scientists investigated the variation in E. histolytica and E. dispar isolates using a PCR assay. Because the microscopic identification of E. histolytica is insensitive and inaccurate, differentiation requires molecular methods. The objectives of the study, as reported by Mojarad, were to determine the prevalence of E. histolytica and E. dispar in stool samples of patients with gastrointestinal disorders; and to identify the genetic variation of E. histolytica and E. dispar isolates. Specific questions included: How genetically polymorphic are the Iranian isolates? How similar are the genotypes of the Iranian strain to the genotypes of other Entamoeba strains? From July 2005 to January 2007, the investigators collected 3,826 fecal samples from three different areas of Iran. Mojarad briefly described the methods and showed slides covering the sample collection by sex and by geographic area, the frequency of E. histolytica and E. dispar by geographic region, and PCR and sequencing results. The investigators found no significant association between infection and diarrhea or other intestinal disorders. Similarly, no significant associations were found between age, sex, or members of the family and the prevalence of E. histolytica or E. dispar. All Iranian asymptomatic cyst passers were infected by E. dispar, a finding that agrees with results from several other studies in Iran. The PCR results were in close agreement with worldwide PCR sequencing analysis. In closing, Mojarad mentioned limitations of the study, including the small number of assays positive for E. histolytica. DISTRIBUTION OF SALMONELLA SUBSPECIES IN IRAN Presenter: Leila Shokrzadeh3 Salmonella is an important zoonotic pathogen that can be spread to humans through many kinds of foods. A Salmonella infection typically causes fever, diarrhea, and gastroenteritis. In his presentation, Shokrzadeh provided an overview of recent outbreaks of salmonellosis, a collection of 3 Shokyzadeh acknowledged the contributions of S. Modorresi, M. Tajbakhsh, and Mohammad Reza Zali.
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Foodborne Disease and Public Health: Summary of an Iranian–American Workshop results from the testing of fecal specimens and selected foods, and information regarding the susceptibility of the organisms to antibiotics. In 2006, three notable Salmonella outbreaks were reported in Iran from different parts of the country. In the first, 65 people were infected by S. typhi from water; in the second, 250 people were infected by non-typhi Salmonella in food; and in the third, 15 people were infected by non-typhi Salmonella. One death was reported. Between 2003 and 2005 in Tehran, various Salmonella serotypes were detected in 6.3 percent of stool samples obtained from patients with diarrhea. When fecal samples were tested from children with diarrhea from many parts of Iran, Salmonella was isolated from fewer than 5 percent of the samples. For the food supply, testing found that about 20 percent of the meat samples and 45 percent of the chicken samples were contaminated with Salmonella. Salmonella Thompson was the most prevalent serotype in both meat and chicken. A study of equipment and surfaces in meat markets detected Salmonella contamination in 12 percent of the markets. A study of chickens found that 68 percent of the animals were infected with various Salmonella serotypes, with Paratyphi C the most prevalent serotype. In a sample of 500 local and 500 commercial eggs, 0.8 percent of the local eggs cultured positive for Salmonella species. Investigators found considerable antibiotic resistance in the non-typhi Salmonella serotypes, especially to nalidixic acid, trimetoprim sulfamethoxazol, and tetracyclin. The organisms were most likely to be sensitive to ciprofloxacin, ceftazidim, cefotaxim, and gentamicin. Related ongoing projects conducted by the Research Center for Gastroenterology and Liver Diseases include the phylogenic analysis of various Salmonella serotypes in Iranian isolates and the investigation of extended-spectrum beta-lacamase-producing bacteria in various isolates. HELICOBACTER PYLORI IN IRAN Presenter: Hosein Dabiri Jaldebakhani Infection with Helicobacter pylori is highly prevalent in Iran. Although it has not been established that this bacterium is transmitted through food or water, H. pylori is of great importance to health because it causes damage to the gastric structure, often resulting in peptic ulcers and sometimes in other serious health problems, including gastric cancer. Many infected individuals show no overt evidence of disease. Dabiri reported on work being done by a group at the Research Center for Gastroenterology and Liver Diseases that focuses on H. pylori. The Research Center for Gastroenterology and Liver Diseases group
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Foodborne Disease and Public Health: Summary of an Iranian–American Workshop diagnoses H. pylori infection using two general methods: various invasive tests that require biopsy through an endoscope; and less invasive tests, mainly the urea breath test, serological tests, and stool antigen tests. Both a seroepidemiologic study and a histopathology study found that the prevalence of H. pylori infection in middle-aged and older adults in different parts of Iran was nearly 90 percent (Malekzadeh et al., 2004). Studies with H. pylori in culture found that patients with ulcers and those without ulcers had similar prevalences of infection (close to 60 percent). Dabiri presented slides giving information about reinfection rates, which appear to be approximately 20 percent (Zendehdel et al., 2005); antibiotic susceptibility; molecular typing; and possible relationships between H. pylori genotype and disease. He showed, for example, that the Iranian genotype in H. pylori is consistent with the European genotype, which has low to mid-level risk for the development of gastric cancer. The Research Center for Gastroenterology and Liver Diseases has a number of ongoing projects related to H. pylori, including the following: An effort to identify H. pylori in Iranian patients with gallstones, atherosclerosis, and chronic sinusitis A prospective study on the recurrence and treatment failures of H. pylori infections An evaluation of non-pylori Helicobacter bacteria in clinical samples A study of how H. pylori interacts with selected non-pathogenic bacteria in an effort to identify probiotics A determination of antibiotic resistance mechanisms in H. pylori in Iranian isolates A restriction-fragment-length polymorphism study of selected virulence genes of H. pylori strains that have been isolated from Iranian patients with and without gastric ulcers THE BURDEN OF GASTROINTESTINAL DISEASE IN IRAN Presenter: Mohammad Reza Zali Overview The purpose of assessing the burden of gastrointestinal disease in Iran is to help guide strategies for its prevention and treatment. Gastrointestinal disorders pose a huge burden on society. One out of every 10 patients who consult a general practitioner in Iran has a gastrointestinal problem. Among the conditions commonly seen in Iran are various forms of gastrointestinal cancer, liver diseases, and a variety of upper and
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Foodborne Disease and Public Health: Summary of an Iranian–American Workshop lower gastrointestinal tract disorders. In particular, Mohammad Reza Zali identified inflammatory bowel disease as highly prevalent. Among the diseases that are increasing in incidence are esophageal and colorectal cancer, hepatitis C, nonalcoholic fatty liver disease, cirrhosis of the liver, Barretts esophagus, pancreatitis, gallstones, diverticular disease, celiac disease, and irritable bowel syndrome. Study Description To obtain current and accurate information on the burden of disease in Iran, Mohammad Reza Zali and colleagues designed a study under the sponsorship of the Shaheed Beheshti University in Tehran. Data were collected over a period of 12 months. Approximately 15,000 individuals were randomly selected from a population of approximately 5.2 million people from both urban and rural settings. These individuals were invited to complete a questionnaire interview and have a clinical examination. The questionnaire covered gastrointestinal signs and symptoms experienced in the previous 6 months, medical history, indicators of the severity of the disorder and of the use of health care services, medication use, demographics, and selected opinions. A validated questionnaire was used in a smaller cross-sectional study that took place from May 2006 to July 2007; 7,150 subjects were randomly selected to participate from a general population of approximately 400,000 people from Damavan, Firozkoh, and Pakdasht. Study Results in Brief Zali showed slides on the prevalence of a large number of gastrointestinal diseases. Gastrointestinal esophageal reflux disease (GERD) and functional abdominal bloating are very common, with prevalence rates that are much higher in females than in males and much higher in middle-aged and older adults than in young people. Of people affected by irritable bowel syndrome, more than 60 percent also had GERD. Of people with GERD, 34 percent also had irritable bowel syndrome. Older subjects were significantly more likely to have both diseases. This strong association between the two diseases—an association that appears to be less common in more developed countries—warrants further study. Because Iran started a vaccination program against hepatitis B nearly 15 years ago, nearly all the people with hepatitis B infections were older than 20 years of age. Beginning in the fifth decade of life, the mortality rate for gastrointestinal disease in Iran increases sharply with age; and it is high overall. Gastric cancer is the largest single contributor to gastrointestinal disease mortality.
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Foodborne Disease and Public Health: Summary of an Iranian–American Workshop Considering the high prevalences of H. pylori (as discussed in the previous section) and of GERD, it could be useful to study their contributions to the development of esophageal cancer in the Iranian population. DISCUSSION Moderator: Mohammad Mehdi Aslani During the discussion period, participants raised questions regarding the methods used for detecting Shiga toxin-producing E. coli (STEC) and concerning the testing that was conducted on cattle feces and foods. Aslani explained that the study on STEC in Iran did not provide a basis for determining whether the STECs are capable of causing disease in humans. Mohammad Zali stated that the purpose of the study investigating the genotype and prevalence of rotavirus infection was to obtain information for a potential vaccination program. Participants also raised questions about different forms of hepatitis and their possible relationship to liver disease in Iran, about possible connections between foodborne pathogens and the long-term diarrhea associated with inflammatory bowel disease, about studies comparing traditional medicine with antibiotic therapy in the control of diarrhea (none has been done), about the prevalence of norovirus infections in Iran (data unavailable), about the sources of antimicrobial resistance (e.g., self-medication with antibiotics suspected), about associations of amoebic infections in patients with Salmonella or a viral infection (no information), and about screening for sapoviruses (not routine in the United States). Responding to Keene’s comments that half or more of the diarrheal outbreaks in the United States are due to norovirus, Mohebbi discussed the limitations in Iran’s detection system for noroviruses that may contribute to that country’s low reported rate of norovirus infection. Beuchat reported on the increase in the percentage of foodborne illness outbreaks attributable to fresh and fresh-cut produce in the United States—a potential food source of illness that has not yet been investigated in Iran. Miller emphasized that the diversity in the production, processing, and distribution of foods in Iran needs to be considered in developing and implementing foodborne illness prevention efforts.