Acute gastroenteritis in children

1. Acute gastroenteritis in children 浙江大学医学院附属儿童医院 江米足

2. What is Gastroenteritis? • Gastroenteritis: nausea, vomiting, diarrhea, abdominal cramping, and fever occur 6-48h after exposure. • Gastroenteritis is second only to respiratory illness as a cause of childhood morbidity worldwide. • Most gastroenteritis is caused by viral infection; bacterial, parasitic (protozoal illnesses are less frequent but not uncommon) and Fungi.

3. Acute gastroenteritis • Description: • viral gastroenteritis • self-limited illness with nausea, vomiting, diarrhea • Organs involved: • limited to gastrointestinal tract (small intestine) • Who is most affected: • children aged 6 months to 2 years • rotavirus can cause acute diarrhea

4. What is diarrhea? • Definition: the passage of excessively liquid or frequent stools with increased water content . • Loose consistency(性状改变): watery diarrhea, mucous diarrhea, bloody diarrhea • Increased stool frequency(次数增多) • Duration • Acute (< 14 d) • Persistent (14 d to 2 m) • Chronic (> 2 m)

5. Etiology of Diarrhea Non infective Infective Food Allergy Symptomatic Overfeeding IntoleranceClimate Viruses Bacteria Parasites Fungi

6. Common Infectious Causes of Diarrhea • Viruses • Rotavirus • Astrovirus • Calicivirus (including norovirus) • Enteric adenovirus

7. Common Infectious Causes of Diarrhea • Bacteria • Campylobacter jejuni • Escherichia coli • EPEC; ETEC; EITC; STEC; EAEC • Shigella • Salmonella • Yersinia enterocolitica • Staphylococcus aureus • Clostridium difficile • Vibrio cholerae • Vibrio parahemolyticus

8. Common Infectious Causes of Diarrhea • Parasites • Entamoeba histolytica (ambiasis) • Giardia lamblia • Cruptosporidium parvum (隐孢子虫) • Strongyloides stercoralis（粪类园线虫） • Blastocystishominis (人牙囊原虫） • Fungi • Candida albicans

9. Causes of acute gastroenteritis in children • Bacteria (10-20%) • Campylobacter jejuni • Non-typhoid Salmonella spp • Enteropathogenic Escherichia coli • Shigella spp • Yersinia enterocolitica • Shiga toxin producing E coli • Salmonella typhi and S paratyphi • Vibrio cholerae • Helminths • Strongyloides stercoralis • Viruses (about 70%) • Rotaviruses • Noroviruses • Enteric adenoviruses • Caliciviruses • Astroviruses • Enteroviruses • Protozoa (<10%) • Cryptosporidium • Giardia lamblia • Entamoeba histolytica

10. Rotavirus and diarrhea • As with most viral pathogens, rotavirus affects the small intestine, causing voluminous watery diarrhea without leukocytes or blood. • Rotavirus, a 67-nm double-stranded RNA virus with at least eight serotypic variants, is the most common.

11. Rotavirus • a REOvirus (Respiratory Enteric Orphan virus) • 4 serotypes based on viral hemagglutinin (Group A rotavirus is most common, but group B and C infections have been documented) • transmission - fecal-oral, respiratory droplet • virus resistant to stomach acid, attaches to beta receptor • shedding of rotavirus can last up to 2 months after severe rotavirus diarrhea • rotavirus can survive on dry inanimate surfaces for 6-60 days

12. Mechanisms of diarrhea • Osmotic • Secretory • Mucosal inflammation (invasion) • Motality

13. Mechanisms of Diarrhea • Osmotic Defect Digestive enzyme deficiencies Ingestion of unabsorbable solute Example Viral infection Lactase deficiency Sorbitol /magnesium sulfate Comment Stop with fasting No stool WBCs

14. Mechanisms of Diarrhea • Secretory Defect Increased secretion Decreased absorption Example Cholera Toxinogenic E.coli Comment Persists during fasting No stool leukocytes

15. Mechanisms of Diarrhea • Invasion Defect Inflammation Decreased colonic reabsorption Increased motility Example Bacterial enteritis Comment Blood, mucus and WBCs in stool

16. Mechanisms of Diarrhea • Increased motility Defect Decreased transit time Example: Irritable bowel syndrome

17. Common infectious causes of diarrhea and their virulent mechanism • Viral diarrhea (osmotic) • Rotavirus • Bacterial diarrhea • Enterotoxinogenic enteritis (secretory) • ETEC • Vibrio cholerae • Entero-invasive enteritis (invasion) • Campylobacter jejuni • EIEC • Shigella species • Salmonella tymphimurium • Yersinia enterocolitica

18. Pathogenesis of enterotoxinogenic enteritis • The mucosa is not destroyed during this process • An imbalance in the ratio of intestinal fluid absorption to secretion, so watery stool may occur in clinical observation

19. Complications of acute gastroenteritis • Dehydration • Metabolic acidosis • Electrolyte disturbance (hypernatraemia, hyponatraemia, hypokalaemia, neonatal hypocalcemia ) • Carbohydrate (lactose, glucose) intolerance • Susceptibility to reinfection • Development of food (cow’s milk, soy protein) intolerance • Haemolytic uraemic syndrome • Iatrogenic complications (due to inappropriate composition or amount of intravenous fluids) • Death

20. What are the clinical characteristics? • Viral infection, with rotaviruses and noroviruses being most common. • Viral infections damage small bowel enterocytes and cause low grade fever and watery diarrhoea without blood. • Rotavirus infection is seasonal in temperate climates, peaking in late winter, but occurs throughout the year in the tropics. • Rotavirus strains vary by season and geographically within countries. • The peak age for infection is between 6 months and 2 years, the mode of spread is by the faecal-oral or respiratory route

21. How is it diagnosed? • Diagnosis can be made clinically. Information include • recent contact with people with gastroenteritis, • nature and frequency of stool and vomitus, • fluid intake and urine output, • Travel • use of antibiotics and other drugs • Diarrhoea and vomiting are non-specific symptoms in young children, • high fever • prolonged symptoms • signs suggesting a surgical cause (such as severe abdominal pain, bilious vomiting, abdominal mass). • Children with diabetes mellitus and inborn errors of metabolism may present with vomiting.

22. History • Chief concern (CC): • acute self-limited diarrhea • nausea • vomiting • most infections in newborns are asymptomatic or mild

23. Clinical manifestation • Gastrointestinal symptom • Acute gastroenteritis—diarrhoea or vomiting (or both) of more than seven days duration • Systemic symptom • May be accompanied by fever, abdominal pain, and anorexia. • Dehydration and electrolyte disturbances • Dehydration • Hypokalemia • Metabolic Acidosis • Hypocalcemia /Hypomagnesemia

24. Physical • General physical • up to one-third have fever > 102 degrees F (39 ℃) • evaluation of dehydration in children

25. How is dehydration assessed? • It is important to assess hydration in gastroenteritis as hydration status determines the immediate management of this condition. • The infant or child with profuse watery diarrhoea and frequent vomiting is most at risk. • Clinicians often overestimate the extent of dehydration. • Documented recent weight lost is a good indicator of the degree of dehydration, but this information is rarely available. • The best clinical indicators of more than 5% dehydration are prolonged capillary refill, abnormal skin turgor, and absent tears

26. Degree of dehydration Clinical signs mild moderate severe Decrease in body weight 3-5% 5-10% 10-15% Skin Turgor normal decreased Markedly decreased Color normal pale markedly decreased Mucous membranes Dry Mottled or gray; parched Hemodynamic signs Pulse normal slight increase tachycardia Capillary refill 2-3 s 3-4 s >4 s blood pressure normal low perfusion normal circulatory collapse Fluid loss urinary output mild oliguria oliguria anuria Tears Decreased absent Urinary indices specific gravity >1.020 anuria Urine [Na+] <20mEq/L anuria

27. Clinical dehydration scale (CDS) • clinical dehydration scale (CDS) using 4 exam features predicts length of stay and likelihood of receiving IV rehydration in young children having acute gastroenteritis

28. CDS points assigned • General appearance • 0 normal • 1 thirsty, restless, lethargic but irritable when touched • 2 drowsy, limp, cold, sweaty, comatose • Eyes • 0 normal • 1 slightly sunken • 2 very sunken • Mucous membranes (tongue) • 0 moist • 1 sticky • 2 dry • Tears • 0 present • 1 decreased • 2 absent

29. CDS classify • CDS (ranges from 0-8 points) classifies children into 3 degrees of dehydration • 0 points - no dehydration • 1-4 points - some dehydration • 5-8 points - moderate/severe dehydration

30. Type of dehydration

31. Laboratory test • Initial laboratory evaluation • CBC • Stool examination: mucus, blood, and leukocytes • Gas and electrolytes analysis • BUN, Cr, and urinalysis for specific gravity • Rapid test for Rotavirus • Stool culture • for patients with fever, profuse diarrhea, and dehydration or if HUS is suspected • Stool evaluation for parasitic agents • identification of the organism in the stool • Blood culture • uncommom

32. What to exclude (differential diagnosis) • Other infections, such as urinary tract infection, otitis media, pneumonia, septicemia • Surgical causes, such as intussusception, appendicitis, small intestinal obstruction (including malrotation) • Taking antibiotics or other drugs • Spurious diarrhoea; for example, in chronic constipation with overflow incontinence • Non-infectious diseases such as diabetic ketoacidosis, inborn errors of metabolism • Occasionally acute infectious gastroenteritis unmasks gastrointestinal disease (such as coeliac disease, chronic inflammatory bowel disease)

33. How is gastroenteritis treated? • Management aims to prevent and treat dehydration, maintain nutrition, and minimise harm. • Optimal management with oral or intravenous fluids minimises the risk of dehydration and its adverse outcomes. • Routine use of drugs such as antibiotics, antidiarrhoeal agents, and antiemetics is not recommended and may cause harm.

34. Which fluid therapy? • Most children are not dehydrated and can be managed at home • Dehydration, metabolic acidosis, and electrolyte disturbance can be prevented and treated by fluid therapy • Mild-moderate dehydration can be treated with oral or enteral rehydration using low osmolality oral rehydration solutions (ORS) • Severely dehydrated or shocked children usually need intravenous fluids and hospital admission

35. Oral rehydration • ORS are preferable to other clear fluids for preventing and treating dehydration • Fluids high in sugar (such as cola, apple juice, and sports drinks, which contain ≤20 mmol/l sodium and have a high osmolality of 350-750 mOsm/l) may exacerbate diarrhoea and should be avoided. • Breast feeding should be continued during acute gastroenteritis and supplemented with an oral rehydration solution if needed.

36. Which oral rehydration solution? • Solutions with low osmolality (200-250 mOsm/l) and sodium (60-70 mmol/l) that contain glucose, potassium, and a base (such as citrate) are recommended for developed and developing communities.

37. 低渗ORS的常用配方 ZJCH

38. If oral intake is inadequate because they dislike the taste, feel nauseated, or have profuse vomiting, a fine bore nasogastric tube is usually well tolerated. Alternatively, fluids may be given intravenously. • Enteral (oral or nasogastric) and intravenous fluids are equally safe and effective for mild-moderate dehydration, rehydration can usually be achieved in 4 to 6 hours. • Children with shock require intravenous resuscitation before rehydration.

39. Iatrogenic complications • The most common adverse effect of intravenous cannulation is infiltration at the cannula site, but infection, pain, bleeding, and physical and emotional trauma may also occur • especially electrolyte disturbance due to inappropriate composition, rate of administration, or volume of intravenous fluids—may lead to complications, including hyponatraemia with brain injury or death. • If rapid intravenous rehydration is used, careful supervision is needed to avoid fluid overload (dehydration is often overestimated) and electrolyte imbalance.

40. What about diet? • Children should resume their normal diet once their appetite returns. • Recommend early reintroduction of milk and solids including complex carbohydrates, lean meats, yogurt, and vegetables, but foods high in fat and sugars should be avoided. • Early refeeding reduces the duration of diarrhoea. • In formula fed infants feeds do not need to be diluted when reintroduced.

41. Is a lactose-free diet necessary? • Carbohydrate (particularly lactose) intolerance is a common complication of viral gastroenteritis as a result of damage to and loss of mature enterocytes containing lactase. • Lactose intolerance is usually mild and self limiting and does not require treatment. • If lactose intolerance persists, a lactose-free formula is recommended for four to six weeks.

42. Intolerance to food proteins • The damaged gut is more permeable to foreign antigens. • Intolerance to food proteins (β lactoglobulin in cow’s milk and other proteins) is occasionally seen after gastroenteritis; • Can be managed by a period of dietary exclusion.

43. What is the role of drugs? • Drugs are rarely needed. • Antibiotics are not indicated in viral or uncomplicated bacterial gastroenteritis and may cause harm. • Antidiarrhoeal, antiemetic agents, and antimotility agents are not recommended for routine use because of the risk of adverse effects.

44. Antibiotics • In non-typhoid Salmonella infections antibiotics increase the risk of prolonged carriage and disease relapse. • Treating gastroenteritis due to Shiga toxin producing E coli with antibiotics may increase the risk of haemolytic uraemic syndrome. • Antibiotics are required, however, for bacterial gastroenteritis complicated by septicemia and in cholera, shigellosis, amoebiasis, giardiasis, and enteric fever.

45. Zinc supplement • In developing countries, oral zinc given at the onset of symptoms decreases the duration and severity of acute diarrhea and is recommended by the WHO and UNICEF. • The dosage and course of treatment • ＜6m：zinc element 10mg； • ＞6m：zinc element 20mg， • Course: 10-14d • Vitamin A does not influence the course of acute gastroenteritis.

46. Can gastroenteritis be prevented? • Environmental sources, such as children’s animal farms, swimming pools, and beaches. • Good hygiene including careful hand washing, nappy disposal, and preparation and storage of food and drinking water. • Hygiene in institutions, including hospitals where nosocomial infection is common. • Oral rotavirus vaccines.

47. When to refer to paediatric service • If diagnosis in doubt • Parent or carer unable to manage the child at home • Gastroenteritis in a young infant (<6 months) • High risk of dehydration—worsening diarrhea and vomiting with significant fluid loss • Severe dehydration or shock • Severe abdominal pain, localised tenderness, or mass

48. When to refer to paediatric service • Evidence of anaemia, thrombocytopenia, poor urine output, or hypertension (think haemolytic uraemic syndrome) • Increased risk of complications—underlying disease (such as diabetes), malnutrition, renal failure, high fever • Persistent diarrhea beyond two weeks may indicate complications such as reinfection, lactose intolerance, or underlying bowel disease

49. Summary • Acute gastroenteritis accounts for millions of deaths each year in young children, mostly in developing communities. • Rotavirus is the most common cause of acute gastroenteritis worldwide.

50. Dehydration, which may be associated with electrolyte disturbance and metabolic acidosis, is the most frequent and dangerous complication. • Optimal management with oral or intravenous fluids minimises the risk of dehydration and its adverse outcomes. • Most children are not dehydrated and can be managed at home