Presentation on theme: "Epidemiology and Management of Diarrheal Diseases"— Presentation transcript:
1Epidemiology and Management of Diarrheal Diseases Amal Mitra, MD, MPH, DrPHProfessorUniversity of Southern MississippiReadings: Diarrhoeal Diseases
2DEFINITION Watery Diarrhea: 3 or more liquid or watery stools in 24 h Dysentery: Presence of blood and/or mucus in stoolsPersistent Diarrhea: Diarrhea lasting for 14 days or moreThe World Health Organization defines diarrhea as the passing of liquid or watery stools at least 3 times in a 24-hour period. However, it is the consistency rather than the number of stools that is important. Frequent passing of formed stools is not diarrhea.Breastfed babies normally passes loose or pasty stools. The mother can tell if her baby has an abnormal stool.If stools contain blood or mucus, it is called dysentery. If diarrhea persists for 14 days or longer, it is called persistent diarrhea.
3TYPES OF DIARRHEAThis chart shows common diarrheal pathogens. There are a number of other pathogens and agents that cause diarrhea. Some of them are as follows:Campylobacter (or Helicobacter pylori)SalmonellaVibrio parahemolyticusGiardia lambliaMore recently, a newer strain of Vibrio, known as “Bengal strain” (Vibrio cholera O139) caused a big epidemic in India, Bangladesh, and some other areas.
8TRANSMISSIONMost of the diarrheal agents are transmitted by the fecal-oral routeSome viruses (such as rotavirus) can be transmitted through airNosocommial transmission is possibleShigella (the bacteria causing dysentery) is mainly transmitted person-to-personFood and water contaminated directly or indirectly with feces or vomitus of infected persons are the principal mode of transmission. Ingestion of raw or inadequately cooked seafood or eating shelfish from coastal and estuarine waters can cause outbreaks of diarrhea. Person-to-person transmission occurs by hand-to-mouth transfer of the agent from feces of an infected individual. Respiratory spread is possible for rotavirus.
9SEASONALITYAlthough diarrhea occurs in any time of the year, outbreak of diarrhea usually follows a seasonal pattern in most developing countries.
10PERSON-AT-RISKCholera: 2 years and above, uncommon in very young infantsShigellosis: more common in young children aged below 5 yearsRotavirus diarrhea: more common in young infants and children aged 1-2 yearsE. coli diarrhea: can occur at any ageAmebiasis: more common among adults
11TYPES OF VIBRIO CHOLERA Two major biotypes of Vibrio cholera that cause diarrhea are:ClassicalElTorTwo common serotypes of Vibrio cholera that cause diarrhea are:InabaOgawa
12Vibrio cholerae O139Vibrio cholerae in O-group 139 was first isolated in 1992 and by 1993 had been found throughout the Indian subcontinent. This epidemic expansion probably resulted from a single source after a lateral gene transfer (LGT) event that changed the serotype of an epidemic V. cholerae O1 El Tor strain to O139.More information:
13Vibrio vulnificusThe organism Vibrio vulnificus causes wound infections, gastroenteritis or a serious syndrome known as "primary septicema." V. vulnificus infections are either transmitted to humans through open wounds in contact with seawater or through consumption of certain improperly cooked or raw shellfish.This bacterium has been isolated from water, sediment, plankton and shellfish (oysters, clams and crabs) located in the Gulf of Mexico, the Atlantic Coast as far north as Cape Cod and the entire U.S. West Coast. Cases of illness have also been associated with brackish lakes in New Mexico and Oklahoma.For more information:
14TYPES OF SHIGELLAThe major serotypes of Shigella that cause diarrhea are:Dysenteriae type 1 or Shigella shigaShigella flexneriShigella sonneiShigella boydii
15TYPES OF E. COLI Six major types of Escherichia coli cause diarrhea: Enterotoxigenic E. coli (ETEC)Enteroinvasive E. coli (EIEC)Enteropathogenic E. coli (EPEC)Enterohemorrhagic E. coli (E. coli O157:H7)Enteroaggregative E. coli (EAggEC)Diffuse adherent E. coli (DAEC)
16CLINICAL FEATURE: CHOLERA Rice-watery stoolMarked dehydrationProjectile vomitingNo fever or abdominal painMuscle crampsHypovolemic shockScanty urineCholera has an acute onset. Death can occur as early as 4-8 hours of onset if the disease is severe. In a day, an adult passes several liters of watery stools of typical fishy smell and rice-water color. Dehydration is often moderate to severe. Some patients are brought unconscious or semiconscious because of hypovolemia. Sings of shock including a low blood pressure, poor or imperceptible pulse, poor skin elasticity, and poor urine output are common.
17CLINICAL FEATURE: E. COLI DIARRHEA Watery stoolsVomiting is commonDehydration moderate to severeFever– often of moderate gradeMild abdominal painE. coli is a less severe watery diarrhea than cholera. However, the clinical presentations may mimic cholera. Usually, patients present with moderate grade fever which is absent in cholera. Also, there may be mild abdominal pain. Features of shock are often less prominent in E. coli diarrhea than cholera.
18CLINICAL FEATURE: ROTAVIRUS DIARRHEA Insidious onsetProdromal symptoms, including fever, cough, and vomiting precede diarrheaStools are watery or semi-liquid; the color is greenish or yellowish– typically looks like yoghurt mixed in waterMild to moderate dehydrationFever– moderate gradeThe most differentiating points of rotavirus diarrhea include: (1) diarrhea in very young kids; (2) flu-like symptoms before diarrhea; (3) stools typically look like yoghurt mixed in water.
19CLINICAL FEATURE: SHIGELLOSIS Frequent passage of scanty amount of stools, mostly mixed with blood and mucusModerate to high grade feverSevere abdominal crampsTenesmus– pain around anus during defecationUsually no dehydrationTypically, presence of altered blood in stools and frequent motions (20 or more times a day) accompanied by high fever and abdominal pain in older children or adults are characteristic features of shigellosis. This disease is often confused with amebiasis, which present with less or no blood, but more mucus, and less frequent motions. In malnourished patients, fever may be less prominent.
20CLINICAL FEATURE: AMEBIASIS Offensive and bulky stools containing mostly mucus and sometimes bloodLower abdominal crampMild grade feverNo dehydrationThe distinguishing features of amebiasis from shigellosis are: (1) usually affect the elderly people; (2) chronic in nature; (3) more mucus and less blood in stools; (4) stools are very offensive; (5) stools are bulky
21LABORATORY DIAGNOSIS Stool microscopy Dark field microscopy of stool for choleraStool culturesELISA for rotavirusImmunoassays, bioassays or DNA probe tests to identify E. coli strainsPresence of fecal leukocytes 20 or more and RBC per high power field of stool microscopy suggests invasive diarrhea (possibly shigellosis). Stool microscopy also reveals parasitic and helminthic infections. Dark field microscopy is a rapid diagnostic test for Vibrio. Stool cultures are available for detecting bacteria including Vibrio cholera, Salmonella, Shigella, and others. Enzyme linked immunosorbent assay (ELISA) is done to detect rotavirus. Antigen tests are done for different serotypes of E. coli.
22ASSESSMENT OF DEHYDRATION Anterior fontanelle: This is the bony junction of the frontal and two parietal bones of the skull. This sign may be found only in infants aged <18 months.
25TREATMENT Rehydration– replace the loss of fluid and electrolytes Antibiotics– according to the type of pathogensStart food as soon as possibleRehydration is the correction of dehydration. Salts and water are lost during diarrhea. These can be replaced by oral rehydration salt (ORS) or intravenous fluids, based on the type of dehydration. Mild and moderate dehydration can be managed by ORS. Severe dehydration should be treated with IV solution.Mutiple antibiotic resistance is a growing problem in many countries. Therefore, antibiotics should be chosen according to the sensitivity pattern of the organism.Food should be started as soon as the patient can eat. Complete withdrawal of food during diarrhea is not recommended. Breastfeeding should be continued throughout the course of diarrhea. Extra protein intake is needed during and after some diarrheal diseases, for example shigellosis.
26COMPOSITION OF ORSHome-made ORS: Sugar or molasses (40 g) can be used as a substitute for glucose to prepare home-made ORS. Common salt (5 g) will be added to it and dissolved in one liter of clean water.Rice-ORS: Rice powder (50 g) can replace the sugar or glucose. The amount of the other salts will remain the same. These will be dissolved in one liter of clean water to prepare rice-based ORS. Studies showed that rice-based ORS can reduce vomiting and diarrhea more in some cases compared to the conventional ORS prepared with glucose.
27AMOUNT OF SALT LOSS DURING DIARRHEA The amount of salt and water loss resulting in dehydration is higher in patients with cholera than other types of diarrhea (Molla et al. 1981). However, loss of potassium is higher and loss of other salts is lower in rotavirus diarrhea compared to other diarrheal diseases. Therefore, kids who commonly suffer from rotavirus diarrhea should be given extra plain water and/or breast-milk in between ORS to prevent hypernatremia (a salt overload).
28ANTIMICROBIAL AGENTSSensitivity pattern of the microbial agents should be checked to select an appropriate antibiotic.
31VACCINESAn oral cholera vaccine is available, which gives immunity to 50-60% of those who take the vaccine, and this immunity lasts only a few months.No vaccines are available against shigellosisA vaccine against rotavirus diarrhea has been withdrawn recently from the market.
32PREVENTION Safe drinking water and food “Boil it, cook it, peel it, or forget it. "Hand washingProper sanitation