Epidemiology and Management of Diarrheal Diseases

Amal Mitra, MD, MPH, DrPHProfessor

University of Southern MississippiReadings: Diarrhoeal Diseases

DEFINITION

• Watery Diarrhea: 3 or more liquid or watery stools in 24 h

• Dysentery: Presence of blood and/or mucus in stools

• Persistent Diarrhea: Diarrhea lasting for 14 days or more

TYPES OF DIARRHEA

R o ta v iru s d ia rrh eaE . co li d ia rrh ea

C h o lera

W atery d ia rrh ea

S h ige llo s isA m eb ia s is

D ysen tery

C a u ses a re m ostly u n k n o w n

P ers is ten t d ia rrh ea

D ia rrh ea

COMMON CAUSES OF DIARRHEA- BACTERIA

– Vibrio cholera– Shigella– Escherichia coli– Salmonella– Campylobacter jejuni– Yersinia enterocolitica– Staphylococcus– Vibrio parahemolyticus– Clostridium difficile

COMMON CAUSES OF DIARRHEA- VIRUS

• Rotavirus• Adenoviruses• Caliciviruses• Astroviruses• Norwalk agents and Norwalk-like viruses

COMMON CAUSES OF DIARRHEA- PARASITE

• Entameba histolytica• Giardia lamblia• Cryptosporidium• Isospora

COMMON CAUSES OF DIARRHEA-OTHERS

• Metabolic diseaseHyperthyroidismDiabetes mellitusPancreatic insufficiency

• Food allergyLactose intolerance

• Antibiotics• Irritable bowel syndrome

TRANSMISSION

• Most of the diarrheal agents are transmitted by the fecal-oral route

• Some viruses (such as rotavirus) can be transmitted through air

• Nosocommial transmission is possible• Shigella (the bacteria causing dysentery) is

mainly transmitted person-to-person

SEASONALITY

Disease Common seasonCholera Winter

Rotavirus diarrhea Winter

Shigellosis Dry summer

PERSON-AT-RISK

• Cholera: 2 years and above, uncommon in very young infants

• Shigellosis: more common in young children aged below 5 years

• Rotavirus diarrhea: more common in young infants and children aged 1-2 years

• E. coli diarrhea: can occur at any age• Amebiasis: more common among adults

TYPES OF VIBRIO CHOLERA

• Two major biotypes of Vibrio cholera that cause diarrhea are:ClassicalElTor

• Two common serotypes of Vibrio cholera that cause diarrhea are:InabaOgawa

Vibrio cholerae O139

• Vibrio 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: http://www.cdc.gov/ncidod/EID/vol9no7/02-0760.htm

Vibrio vulnificus• The 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: http://hgic.clemson.edu/factsheets/HGIC3663.htm

TYPES OF SHIGELLA

• The major serotypes of Shigella that cause diarrhea are:Dysenteriae type 1 or Shigella shigaShigella flexneriShigella sonneiShigella boydii

TYPES 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)

CLINICAL FEATURE: CHOLERA

• Rice-watery stool• Marked dehydration • Projectile vomiting • No fever or abdominal pain• Muscle cramps• Hypovolemic shock• Scanty urine

CLINICAL FEATURE: E. COLI DIARRHEA

• Watery stools• Vomiting is common• Dehydration moderate to severe• Fever– often of moderate grade• Mild abdominal pain

CLINICAL FEATURE:ROTAVIRUS DIARRHEA

• Insidious onset• Prodromal symptoms, including fever,

cough, and vomiting precede diarrhea• Stools are watery or semi-liquid; the color

is greenish or yellowish– typically looks like yoghurt mixed in water

• Mild to moderate dehydration• Fever– moderate grade

CLINICAL FEATURE:SHIGELLOSIS

• Frequent passage of scanty amount of stools, mostly mixed with blood and mucus

• Moderate to high grade fever• Severe abdominal cramps• Tenesmus– pain around anus during

defecation• Usually no dehydration

CLINICAL FEATURE:AMEBIASIS

• Offensive and bulky stools containing mostly mucus and sometimes blood

• Lower abdominal cramp • Mild grade fever• No dehydration

LABORATORY DIAGNOSIS

• Stool microscopy• Dark field microscopy of stool for cholera• Stool cultures• ELISA for rotavirus• Immunoassays, bioassays or DNA probe

tests to identify E. coli strains

ASSESSMENT OF DEHYDRATION

DehydrationMild Moderate Severe

Appearance irritable,thirsty

irritable,verythirsty

lethargy,coma, orunconscious

AnteriorFontanelle

normal depressed markedlydepressed

Eyes normal sunken sunken

ASSESSMENT OF DEHYDRATION (contd.)

DehydrationMild Moderate Severe

Tongue normal dry very dry,furred

Skin normal slowretraction

very slowretraction

Breathing normal rapid very rapid

ASSESSMENT OF DEHYDRATION (contd.)

DehydrationMild Moderate Severe

Pulse normal rapid andlowvolume

feeble orimperceptible

Urine normal dark scanty

Weightloss

< 5% 6 - 9% 10% or more

TREATMENT

• Rehydration– replace the loss of fluid and electrolytes

• Antibiotics– according to the type of pathogens

• Start food as soon as possible

COMPOSITION OF ORS

Ingredient Amount (g/liter)Sodium chloride 3.5

Trisodium citrate orSodium bicarbonate

2.9 or2.5

Potassium chloride 1.5Glucose 20.0

AMOUNT OF SALT LOSS DURING DIARRHEA

Salt (mmol/L) Diarrhea Na K Cl HCO3

Cholera (child)

88 30 86 32

Cholera (adult)

135 15 100 45

E. coli 53 37 24 18 Rota virus

37 38 22 6

ANTIMICROBIAL AGENTSType of diarrhea Antimicrobial agentCholera Tetracycline,

Doxycycline,Ciprofloxacine

Shigellosis Pivmecillinam(Selexid), Nalidixicacid, Ciprofloxacin,Ceftriaxone

Amebiasis Metronidazole

COMPLICATIONS:WATERY DIARRHEA

• Dehydration • Electrolyte imbalances• Tetany• Convulsions• Hypoglycemia• Renal failure

COMPLICATIONS:DYSENTERY

• Electrolyte imbalances• Convulsions• Hemolytic uremic syndrome (HUS)• Leukemoid reaction• Toxic megacolon• Protein losing enteropathy• Arthritis• Perforation

VACCINES

• An 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 shigellosis• A vaccine against rotavirus diarrhea has been

withdrawn recently from the market.

PREVENTION

• Safe drinking water and food“Boil it, cook it, peel it, or forget it. "

• Hand washing • Proper sanitation