FOOD-BORNE DISEASE Elemanov Nurlan PLAN I Food-borne

FOOD-BORNE DISEASE Elemanov Nurlan

PLAN I. Food-borne diseases II. Epidemiology III. Diagnosis

I. FOOD-BORNE DISEASES Infectious diseases spread through food or beverages are a common, distressing, and sometimes lifethreatening problem for millions of people in the United States and around the world. The Centers for Disease Control and Prevention (CDC) estimates that each year in the United States, 1 in 6 Americans (or 48 million people) gets sick, 128, 000 are hospitalized, and 3, 000 die of foodborne diseases.

I. FOOD-BORNE DISEASES There are more than 250 known foodborne diseases. They can be caused by bacteria, viruses, or parasites. Natural and manufactured chemicals in food products also can make people sick. Some diseases are caused by toxins from the diseasecausing microbe, others by the human body’s reactions to the microbe itself.

I. FOOD-BORNE DISEASES To better understand the epidemiology (study of disease origin and cause in a community) of foodborne diseases in the United States, 10 states across the country collect annual data on the occurrence of new cases of the most common causes of bacterial and parasitic infections through the Foodborne Diseases Active Surveillance Network, a CDC-sponsored program known as Food. Net.

I. FOOD-BORNE DISEASES Foodbor ne disease is a pervasi ve pr oblem caus ed by cons umpti on of cont aminated food and drink. More t han 200 p athog en s are as so ci ated with food bor ne disease. An estim ate d 76 million cases occur annual l y (one i n ever y four Amer icans), res ulting i n 300, 000 hospit aliz atio ns and 5 , 0 0 0 deaths. Fewer cases are do cume nted becau se of und err eporti ng. International t r avel and food importation have further expanded the pr oblem. The onset of foodborne disease is g ener ally acute, with r esolution of an uncom pl icated i l lness in 72 hou r s for most epi so des. P ro per food handling and preparation, per sonal hygiene, and im prov ed methods of decont am ination o f cons umer pr oduct s could si gnifi ca ntl y r educe the extent of m orbi dity and mortality of t his com m on probl em.

I. FOOD-BORNE DISEASES Fo od borne illness is t racked in the Unit ed Sta tes through a system called Fo od Net, a joint effort of t he U. S. Food an d Drug A dministration (FDA) and the U. S. Dep artment of Agricultu re (USDA). Da ta are c ollected annu ally from ten dif f ere nt mo ni toring sites thr oughout the c ountry (representing 15% of the pop ula tio n) and compiled by the Centers for Dise ase Co ntrol and Prevention (CDC). On ly d oc umented cases are used for re porting. The targ et organisms in clude Camp ylobacter spp. , Salmonella spp. , Sh igel la spp. , Lister ia spp. , Shiga toxin-producing Escherichia co li O 1 57: H 7 (STEC O 157), non-O 157 STEC, V ibrio spp. , Yersinia spp. , Cryptosp or idium sp p. , and Cyclospora spp. The he mo lyt ic-uremic syndrome (HUS) is also tracked.

II. EPIDEMIOLOGY Fo od borne d isease can be caused by ba cteria, parasites, t oxins, and viruses. Despite efforts to inve stigate foodborne disease, less th an 5 0% of all outbreak causes a re identifi ed, usually because of limited diagnostic capabilities. Viruses are lik ely the most common ca use of fo od borne disease but are se ldom investigated and confirmed bec ause o f the short du ration and sel f-lim ited nature of the illness. In add itio n, the inherent difficulty of labora tory investigation and subsequent cost of vir al studies lea d to a lack of clinician i nv est iga tio n and therefore overall und erre porting. Bacteria are the m ost common documented cause.

II. EPIDEMIOLOGY Cu ltu ral and dem ographi c factors, as well as increas ed m obil ity, ha ve r esu lt ed in major epidemiol ogic shift s in foodborne dis eas e during r ecent decades. 2 Prev ious out breaks of foo dbo rne dis eas e were smaller and l imited i n scope, more often orig inated in the ho me , and were as soci ated with Staphylococ cus or Clos trid ium spp. Family picnics or di nners and home-canned foods were the t ypical sour ces for the outbre aks. Today, many more pe ople dine out side t he home and travel more extensively. As a re sult, m ore tha n 80% of foodborne disease cases occu r fr om expos ures o uts ide the home.

II. EPIDEMIOLOGY Techno logy has provided the means for mass production and d istrib uti on of food. Therefore, f oodborne d isease often occu rs on a m assive sc ale, whereby hundreds or t ho usand s are exposed and may bec om e ill. Mobility and tr avel have resulted in exposure to foods abroa d, where regulation of food safet y a nd food products for sale m ay va ry. When traveling, the ax iom “boi l it, peel it, cook it, or forget it” remains true in many a rea s of the world. Travelers bri ngin g home unique foods as gifts ma y unw ittingly expose family m em bers a nd friends to unexpected illne ss. International ships disc ha rging their bilge in ports are a no ther possible means of d isseminating pathogens.

II. EPIDEMIOLOGY Food importation has steadily increased to meet the demand for seasonal and nonseasonal foods. Conditions of production and harvest may be unsupervised or uncontrolled, with resultant importation of contaminated foods. Raw manure is frequently used as fertilizer, causing contamination of fresh produce. If improperly cleaned, the fertilized produce may cause illness when consumed.

II. EPIDEMIOLOGY Unique ethnic food preferences and preparation have been associated with several food-related illnesses. One example is the African American tradition of eating chitterlings (cooked swine intestines) during the Christmas holiday season. This food has been associated with an outbreak of Yersinia enterocolitica infection in infants. Fresh cheese made from unpasteurized milk has been associated with episodes of listeriosis in Hispanic neighborhoods.

II. EPIDEMIOLOGY Foodborne disease is more likely to affect the extremes of age as well as immunocompromised patients and pregnant women. These groups suffer higher incidence, morbidity, and mortality. The effect of foodborne disease may extend beyond the immediate illness. This has been shown by a Danish study, which demonstrated a greater than threefold risk of dying in the year after contracting a foodborne illness.

II. EPIDEMIOLOGY Most foodborne disease has a short duration of illness and a self-limited course. Others may cause a more protracted illness, such as Cryptosporidium and. Cyclos pora. However, some foodborne diseases are associated with long-term chronic sequelae. Salmonella, Shigella, Yersinia, and Campylobacter spp. are linked to reactive arthritis; Campylobacter has also been associated with the Guillain-Barré syndrome, and STEC O 157: H 7 has been linked to renal failure.

II. EPIDEMIOLOGY The most commonly identified pathogens are Campylobacter spp. , Salm onella spp. , Shigella spp. , and STEC O 157: H 7. These organisms have evolved and now have greater cold, heat, and acid tolerance, as well as resistance to multiple antibiotics. Increased drug resistance has been associated with prolonged illness and a greater risk of hospitalization. Almost any food can be a source of foodborne disease. Some foods are more commonly associated with particular organisms. Salmonella has traditionally been associated with poultry and eggs, Campylobacter with chicken and unpasteurized milk, and STEC O 157: H 7 with ground beef. An outbreak of STEC O 157: H 7 was associated with steak that had been needle-tenderized, thereby exposing the center of the meat to surface organisms. When the steak was not thoroughly cooked to an adequate internal temperature, the microorganisms survived and illness occurred after consumption.

II. EPIDEMIOLOGY Wa ter may b e the vector of illness when c ontaminated with viruses, bacteria, p arasites, or chemicals. Cr ow ding, poor san ita tion, d isruption of water supplies, a nd natur al disasters are closely linked to wa te rborne illness. Vir uses are the most c ommon cause of waterborne illn ess and include rotaviru ses, enteric a den oviru s , astrovirus, caliciviruses and hep atitis A virus. O utbreaks of gastroente ritis aboard cru ise ships in rec ent years were a result of n orovirus es. Salmonella spp. , Shigella s p p. , E. c oli , and Vibrio sp p. are the pred ominant bacterial pathogens involved. Cryptosporidium spp. and Giardia lamblia are the parasitic pathogens most commonly encountered in water-bor ne illness. Immu nocompromised hosts, p articularly organ transplant recipients and HIVinf ected patie nts, should exercise extra p recau tio n in situations of potential waterborne illness.

II. EPIDEMIOLOGY Incubation periods of foodborne disease may offer clues to the cause. Four time frames may be envisioned: very brief, short, intermediate, and long durations of incubation. The very brief category (<8 hours) is generally caused by preformed toxins, which may be found in staphylococcal or bacillus-contaminated food. Short incubation periods (24 -48 hours) are more typical of viral causes. Intermediate incubation periods (1 -5 days) correlate with many bacterial pathogens. The long-duration incubation group (>5 days) approximates the time course of parasitic infections. These time frames are crude groupings and areas of overlap exist between them. In addition, the inoculum of organisms ingested may influence the incubation period and the rapidity of onset of illness—for example, a large inoculum may cause a shortened time to onset of illness.

III. DIAGNOSIS Dia gn osis is accomplished through a ca re ful history, physical examination, and labora to ry evaluation. The history sh ould inc lude questioning about the suspec ted time of exposu re, recent trave l, the f ood and drink consumed, o ther p eople who may have been p re sent a nd eaten similar foods, and t he spec ific symptoms involved (e. g. , n ausea , vomiting, diarr hea with or wit ho ut visi ble blood, cr amp ing, gas, f eve r, ne urolo gic symptoms, alteration of m en ta l sta tus). Dietary history may in clude inta ke during the last 2 to 3 week s. The physical examination should foc us on vital signs, including ortho static measurements, skin turgo r, mental status, ab dominal fin din gs, a nd stool testing for blood. F resh sto ol samples for culture and an alysis (<6 hours old) pr ovide the highest yield.

III. DIAGNOSIS The clinician mus t be knowledgeab le of the l aborato ry's assay pr oced ures to facilitate pr oper sample testing. Specific cultur e requ ests for s uspe cted org anisms may be necess ary, as well as micr oscopic examinati on of stool s amples for paras ites. Thre e samples on different days wil l g ener ally provide adequate diagnos tic resul ts. Special cir cumstances may di ctate the need to perform s pecial ass ays for t oxins (e. g. , b otul inum toxin) on g astr ic asp ir ates o r s tool sampl es. Blood cu lt ures are often us eful, part icu larly if Sa lm on ella or List eria is su spected or w hen e valuation involves high-risk groups and immu nocompr om is ed hos ts.