1. Rotavirus, Hepatitis A and other Food and Waterborne Viral Infections of the Gl Tract Part I: Gastroenteritis
Jason B. Harris, MD. MPH.

2. Viral Classification

3. Part I: Rotavirus and Gastroenteritis

4. Rotavirus: Overview
Rotavirus is the most important cause of severe gastroenteritis in infants and toddlers world wide.
It is excreted in the feces and acquired through ingestion yet there is nearly univeral acquisition by age 2.
Any ideas why?

5. Rotavirus: Epidemiology
Universally acquired in the first few years of life in developing and developed world.
The most common cause of diarrhea in children less than 5 years of age.
Shed in high concentration in stool 1011 particles/mL
Low ID50 (10 plaque-forming units)
Physically hardy
No animal reservoir for predominantly human strains
(Rare reassortants may contribute to genetic diversity)
These factors may contribute to the epidemiologic differences between rotavirus and other classic food and waterborne illnesses

6. Rotavirus: Microbiology
70 nm icosahedral virus representing a distinct genus of Reoviridae
Genome consists of 11 segments of dsRNA, encoding 12 proteins

7. VP7: Glycosylated protein, correspond with G type neutralizing antibody
VP4: Cleaved by trypsin (to VP5 and 8), corresponds with P type neutralizing antibody
VP2

8. Rotavirus: Pathogenesis
Rotavirus replicates in epithelial cells of the small intestine
Damage to intestinal epithelial cells and brush border, but limited inflammation.
Diarrhea thought to be due to:
Destruction of brush border epithelial cells decreases the enzymatic digestion of foods and absorptive capacity for carbohydrates
Age dependent sensitivity to NSP4 an enterotoxin made by rotavirus.
Activation of enteric nervous system may contribute to pathogenesis
Previous infection leads to incomplete protection against subsequent disease.

10. Rotavirus: Classification
Rotavirus is classified into seven genogroups
Electrophoresis pattern of the 11 dsRNAs.
Human pathogens are group A rotaviruses.
G and P serotypes – based on neutralizing antibodies to VP7 glycoprotein (G) and VP4 protease cleaved protein (P):
>60 different G and P types
Relatively limited combinations of G and P types among predominant circulating
Five strains cause >90% of disease – (G1P[8], G2P[4], G3P[8], G4P[8], G9P[8])
Limited combinations of G and P type suggest limited reassortment.

11. Rotavirus: Epidemiology
Characteristic
Classic food and waterborne
Rotavirus
Distribution
Greater incidence in resource-limited countries
Equal incidence in developed and resource-limited countries
Sanitation
Improved sanitation reduces incidence
No effect on incidence
Seasonality
During, and after rainy season in developing countries
Winter seasonality in temperate climates similar to influenza, RSV and measles

12. Rotavirus: Geographic spread

13. Rotavirus: Approximate Burden
Parameter
U.S.
Global
Seropositive by age 3
> 95%
Incidence
1 in 1.4
1 in 1.2
Physician visits
1 in 6.5
1 in 50 (?)
Hospitalizations
(N)
1 in 70
65,000
2,400,000
Deaths
1 in 100,000 30
1 in 250
450,000
Costs
$1 billion
From: Clark et al. Rotavirus. Vaccines (5th edition)
And Patel MM, et al. Lancet ID. July 2012

15. Rotavirus: Protective Immunity

16. Rotavirus: Typical clinical manifestations
Incubation period 2-7 days.
Abrupt onset emesis and fever
Profuse, watery stools follow.
Stool rarely contains blood, WBCs.
Irritability frequent.
Emesis decreases hours.
Diarrhea decreases 2-7 days.

17. Rotavirus: Clinical manifestations

18. Rotavirus: Complications
Dehydration
Acidosis
Hypo/Hyper-natremia
Febrile seizures.
Reye’s syndrome, encephalitis, rectal bleeding and intussusception reported.
Increased transaminases from gut damage, not hepatitis.

19. Rotavirus: Diagnosis
No etiologic diagnosis usually needed for management of patients with acute watery diarrhea
Diagnosis now made by various antigen detection tests, this can be done by ELISA, latex-agglutination, rapid (strip based) tests (VP6)
RT-PCR used for studies

20. Rotavirus: Treatment
Approach to management of patients with acute watery diarrhea primarily supportive and based on syndrome – not specific to the etiologic agent.
ORS is a low cost, effective intervention.
IVF frequently used.

21. Rotavirus: Vaccines (and post-licensure lessons)
Rotashield.
Wyeth-Lederle.
4-valent attenuated simian-human reassortant.
Licensed 1998 in U.S. and withdrawn 1999.
Rotarix (RV1).
GSK.
Attenuated human strain - G1P[8].
Currently licensed in > 100 countries.
RotaTeq (RV5).
Merck.
5-valent attenuated bovine-human reassortant – G1, 2, 3, 4 and P[8].

22. Rotashield
Consisted of simian RRV P5[3]G3 reassortant with VP7 derived from three human G types 1, 2, and 4.
G1 only vaccines provide homotypic and some heterotypic protection, but efficacy studies showed improved protection monovalent G1 vaccine; early data arguing for inclusion of multiple serotypes.
Reports of intussusception leading to post-licensure removal

23. Intussusception Life-threatening telescoping of the bowel
Approximately 2000 U.S. cases per year annually
Translates to incidence of about 1:2,500
Peak age 4-9 months
From Irish et al. E-medicine

24. Rotashield: Intussusception
Pre-licensure: 11,000 vaccine recipients, 4,500 placebo recipients. Intussusception in 6 subjects (5 in vaccine group, 1 in placebo).
July cases of intussusception reported through the Vaccine Adverse Event Reporting System (VAERS) after 1 million children were vaccinated.
Triggered suspension of use and CDC case control study.

26. 17% of cases and 12% of controls had rcvd rotashield
30 fold increased risk in the first week after the first dose of vaccine.
1 case of intussusception for every 10:000 vaccinees.
N Eng J Med 2001; 344:

28. Why the association?
RRV more invasive for GALT compared to human rotavirus or other animal-human reassortant viruses?

30. Yen, C. et al. Pediatrics 2011;127:e9-e15
FIGURE 1 Number of diarrhea-associated and rotavirus-coded hospitalizations (A) and hospitalizations per non-diarrhea-associated hospitalizations (B) among children <5 years of age at 62 NACHRI hospitals between July 2003 and June 2009
Yen, C. et al. Pediatrics 2011;127:e9-e15
Copyright ©2011 American Academy of Pediatrics

31. Number and proportion of New Vaccine Surveillance Network (NVSN) hospitalized children <3 years of age with acute gastroenteritis (AGE) who tested positive for rotavirus, by year.
Number and proportion of New Vaccine Surveillance Network (NVSN) hospitalized children <3 years of age with acute gastroenteritis (AGE) who tested positive for rotavirus, by year.
Payne D C et al. Clin Infect Dis. 2011;53:
Published by Oxford University Press on behalf of the Infectious Diseases Society of America 2011.

32. Predominant rotavirus serotypes among hospitalized children <3 years of age, New Vaccine Surveillance Network (NVSN), January–June, 2006–2009.
Predominant rotavirus serotypes among hospitalized children <3 years of age, New Vaccine Surveillance Network (NVSN), January–June, 2006–2009.
Payne D C et al. Clin Infect Dis. 2011;53:
Published by Oxford University Press on behalf of the Infectious Diseases Society of America 2011.

33. Age distributions for hospitalized rotavirus cases.
Age distributions for hospitalized rotavirus cases. Median ages and mean ages with 95% confidence intervals (CIs) are given in months for the period 2006–2009 among children <3 years old reported by the New Vaccine Surveillance Network (NVSN).
Payne D C et al. Clin Infect Dis. 2011;53:
Published by Oxford University Press on behalf of the Infectious Diseases Society of America 2011.

34. Post-licensure monitoring reveals novel rare adverse events and significant shifts in disease epidemiology
Demonstrates utility of passive and active surveillance for safety issues (VAERS, Vaccine Safety Datalink respectively)

35. Rotavirus vaccines
WHO recommends that rotavirus vaccination be included in all national immunization programs.
Funding support though GAVI Alliance

36. Rotavirus vaccines in developing countries: Less but more?

39. Rotavirus: Taking stock
How soon will other resource limited countries adopt rotavirus vaccination?
Once adopted will the lower immunogenicity present a significant barrier to vaccine efficacy?
Will additional boosters be necessary?
How will vaccination influence the epidemiology of childhood gastroenteritis over time?
Serotype
Age distribution
Hospitalizations/fatalities.

40. Caliciviridae

41. Caliciviridae Norovirus Sapovirus Formerly Norwalk-like virus
Among the most important causes of gastroenteritis in children and adults?
Emerging infection?
Sapovirus
Cause of sporadic gastroenteritis

42. Norovirus: Classification

43. Norovirus: Epidemiology
Transmitted by fecal-oral spread.
Low inoculum required.
Environmentally hardy.
Antigenic variation in emergent variants
Well known to be responsible for explosive outbreaks of gastroenteritis
Food and waterborne sources
Increasing recognition of its role in sporadic cases of gastroenteritis, though limited data.

44. Norovirus: Epidemiology

45. Norovirus: Clinical Manifestations.
Classically an abrupt onset of vomiting. “Winter vomiting disease.”
Incubation period 1-2 days.
Illness of short duration, hours.
Vomiting occurs in > 50% of cases.
Complications are thought to be less common than in rotavirus or bacterial enteric infections, major complication is dehydration.

46. Norovirus: Management
Diagnosis of acute vomiting and diarrhea not usually necessary for individual patients
RT-PCR
Immunoassays
Management is supportive
Dehydration

47. Acute gastroenteritis case study
Vomiting and diarrhea on military ship
34 of 102 soldiers with vomiting and/or diarrhea, over 5 day period
Onset of first case 1 day after leaving Lima, Peru
65% body aches, 50% fever
40% infected reported to infirmary
No deaths

48. If you were asked to investigate this how might you address causation?

50. Part II: Food and Waterborn Viral Hepatitis

51. Viral Hepatitis
Many systemic viruses have some tropism for hepatocytes and can cause acute hepatitis, but usually self limited.
Eg. EBV, CMV, mumps, adenovirus and many others
Several viruses have specific tropism for hepatocytes and may cause fulminant acute hepatitis or chronic hepatitis.

52. Major Viral HepatitidesB C D* E
Family
picorna
hepadna
flavi
delta
hepe
(calici)
Nucleic acid
RNA
DNA
Incubation
15-50
28-160
14-160
15-60
Transmission
Orofecal X
Blood
Sexual
Chronic infection
HCC
(NA)

53. Hepatitis A Historically distinguished as epidemic jaundice Will cover
Microbiology and pathogenesis
Epidemiology
Clinical aspects
Vaccination and prevention

54. Hepatitis A: Microbiology
28 nm icosahedral, nonenveloped RNA virus
Member of the Picornaviridae family, which includes enteroviruses and parechoviruses
Single positive strand of RNA encodes all proteins
Only a single serotype identified, several genogroups identified but relatively high degree of similarity (relatively genetically monomorphic).

55. Hepatitis A: Pathogenesis
Remarkably poor growth in cell culture.
No obvious cytopathic effect in vitro
Cellular receptor havcr-1 (TIM1) identified, but expressed ubiquitously.

56. Hepatitis A: Epidemiology
Fecal-oral transmission, food and waterborne transmission common.
Epidemiologic pattern varies globally by level of endemnicity
In areas of high endemnicity, infection is almost universal, asymptomatic infection of young children predominates
In areas of moderate endemnicity where there remains a pool of susceptible older children and young adults, large common source food and waterborne outbreaks may occur.
In areas of low endemnicity, community wide and potentially larger outbreaks occur in setting of susceptible population.
Person-to-person spread is also a major mode of transmission

57. Hepatitis A: (Serologic) Prevalence
High ~ 85% by age 5, >90 by age 10.
Intermediate ~ 30% by age 5, ~50% by age 10
Low, variable, but <10% may reach 20-30% by 4th decade. This may be further reduced by vaccination

58. Hepatitis A: U.S. Incidence
Vaccine licensed 1996

59. Hepatitis A: Source of transmission

60. Hepatitis A: Clinical Features
Prolonged incubation period (15-50, median 30 days).
Spectrum ranging from asymptomatic, to flu-like illness, to fulminant hepatitis.
Underlying liver disease is a major risk factor for severe disease, especially Hepatitis C
Age specific attack rates:
70-90% of infections in young children are asymptomatic or subclinical.
70-90% of infections in adults result in jaundice

61. Hepatitis A: Clinical manifestations
Nonspecific symptoms:
Fever, malaise, anorexia, vomiting, nausea, abdominal pain or discomfort, and diarrhea.
Rash and arthralgias may occur.
Elevated aminotransferases
Findings associated with acute hepatitis:
Dark urine, acholic stool, jaundice, pruritus, hepatomegaly
Aminotransferases > 1000.
Fulminant hepatitis with liver failure:
Occurs in < 1% of cases overall.
Encephalopathy, coagulopathy, other systemic and metabolic derangements

62. Hepatitis A: Atypical manifestations and complications
Cholestasis – uncommon, but usually self-resolving
Relapsing disease (~10%)
Immunologic diseases
Leukocytoclastic vasculitis
Glomerulonephritis
Arthritis
Cryoglobulinemia
Myocarditis
Optic neuritis
Transverse myelitis

63. Hepatitis A: Diagnosis
Serum IgM is the mainstay of diagnosis
As with other serologic tests timing is a critical issue
False negative early in the course of illness
RNA detection possible but not routinely used for clinical purposes

64. Hepatitis A: Clinical Course
From: Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases, 7th ed., Wasley, Feinstone, Bell.

65. Hepatitis A: Vaccines and Prevention
Hepatitis A can be prevented by both passive and active immunization
Passive immunization
Used pre-exposure and as post-exposure prophylaxis.
Human immune globulin.
Active immunization
Several similar licensed vaccines, all grown in cell culture, purified and inactivated by formaldehyde and administered with alum.
Havrix (GSK) and VAQTA (Merck) are approved in U.S.
Two dose schedule

66. Hepatitis A vaccine in U.S.: Pre-exposure recommendations
Incorporated into routine vaccination schedule (ACIP recommendations) 2006.
Other considerations include
International travelers
MSM
IDU
HIV
CLD
Contacts with known case
International adoption

68. Hepatitis A vaccine post-exposure
ACIP recommendations modified in 2007 to accommodate findings
Either IG or vaccine can be used for post-exposure prophylaxis, though vaccine is preferable in persons without contraindications.

69. Hepatitis E

70. Hepatitis E
Unique among causes of viral hepatitis in association with severe disease during pregnancy.
Pattern of disease different in developing versus developed countries.
Fecal oral transmission via food and water in developing countries
Rare sporadic disease, zoonotic, in developed countries (HEV3)

71. Hepatitis E Virus: Genomic Structure

72. Hepatitis E: Classification
4 genotypes:
Genotype 1 (Asia and Africa)
Genotype 2 (Mexico and Africa)
Genotype 4 (Asia)
Genotype 3 (North America, Europe)
Single serotype with protection across genotypes, with neutralizing antibody response against PORF2 epitope

73. Hepatitis E

74. Modified from Arankalle VA, Tsarev SA, Chadha MS, et al
Modified from Arankalle VA, Tsarev SA, Chadha MS, et al. Age-specific prevalence of antibodies to hepatitis A and E viruses in India, 1982 and J Infect Dis. 1995;171: )

75. Hepatitis E: Epidemiology
Das K, Agarwal A, Andrew R, et al. Role of hepatitis E and other hepatotropic virus in aetiology of sporadic acute viral hepatitis: a hospital-based study from urban Delhi. Eur J Epidemiol. 2000;16: ; and Ghabrah TM, Strickland GT, Tsarev S, et al. Acute viral hepatitis in Saudi Arabia: seroepidemiological analysis, risk factors, clinical manifestation, and evidence for a sixth hepatitis agent. Clin Infect Dis 1995;21:

76. Hepatitis E: Epidemiology
Person-to-person transmission less frequent than with Hepatitis A.
Large food and waterborne epidemics.
Risk of clinical disease is dose dependent
Suspected zoonotic disease in Japan and U.S. with human isolated closely related to genotype commonly isolated from swine (HEV3)

77. Hepatitis E: Developed Countries
21% seropositivity in U.S. residents
Of small number of suspected cases based on clinical presentation and seropositivity in U.S., only a handful confirmed by molecular diagnostics
Disease associated with transplantation/immunosuppression.
HEV3 common in swine

78. Hepatitis E: Clinical Features
Similar incubation period and time course of illness as in hepatitis A (15-40 day incubation period)
Illness is similar to hepatitis A and other causes of acute viral hepatitis.
Different features in pregnancy

79. Hepatitis E: Pregnancy
Accounts for over 80% of cases of fulminant hepatitis during pregnancy.
Mortality may exceed 25% in the third trimester (~1% overall)
Often presents in conjunction with cholestatic disease
Reason for increased risk is unknown.
Major obstetric complications including PROM, IUGR.
Vertical transmission reported.

80. Hepatitis E: Treatment & prevention
Supportive care only
Chinese vaccine

81. Hepatitis outbreak case study
A single county in MI reported 78 cases of hepatitis A over a 4 week period.
Most cases associated with a single school.
What types of initial investigations might be useful?

82. Open ended interviews – hypothesis generation
Case-control study – measure Odds Ratios
(odds of exposure in cases vs. controls)
Cohort study – measure Relative Risk
(ratio of the probability of infection occurring in the exposed group versus a non-exposed group)
Molecular epidemiology – assess clonality of outbreak, origin of strain by phylogenetic comparison with previously described isolates

84. Hep A outbreak continued
Contemporaneous clusters of cases in Maine and another MI county also linked to frozen strawberries from same distributor
FDA involved in investigation, foods traced backwards (to four growing fields in Mexico), and withdrawn.
Frozen berries also traced forwards to 20 other cases in 4 states.
Genetic analysis revealed largely clonal outbreak of hepatitis A.

86. Lessons
Church-picnic model of foodborne outbreak investigation does not capture the complexity of large and often geographically diffuse outbreaks.
Complexity of food production and distribution
Molecular epidemiology is critical to detection and understanding of such diffuse outbreaks.

87. Part III: Enteroviruses and Systemic Disease

88. Medically important enteroviruses
Nonpolio enteroviruses
(and parechovirus 1 and 2)
Poliovirus
Serotypes 1-3
Heterogeneous Clinical Spectrum
Non-specific febrile illness
Respiratory infection (classic herpangina)
Skin (classic hand-foot and mouth)
Neurologic (meningitis, encephalitis)
GI (gastroenteritis)
Cardiac (myocarditis)
Muscle (myositis)
Ocular (conjunctivitis)
Severe systemic (neonatal sepsis)
Former sub genera classification
Enterovirus
Echovirus
Coxsackie virus A
Coxsackie virus B
Serotype designation (>100)
Current genetic species
HEV- A-D as species
Old serotype designation still used to describe individual strains

89. Enteroviruses: Virology
Picornavirus
Relatively environmentally hardy
Antigenic component usually primarily determined by VP1.
Diverse serologic classification with over 100 serotypes.

90. Enterovirus: Pathogenesis
Dr Richard Hunt, pathmicro.med.sc.edu/virol/picorna.htm

91. Enteroviruses: General Epidemiology
A summer disease in temperate climates, a year round infection in tropical climates
Shed in saliva and stool.
Significant direct person to person spread.
Also spread by contaminated food and water
Usually a few predominant strains associated with disease in any given season.

92. Polio Majority of cases are asymptomatic
Non-specific illness in < 10% of infected person (primary viremia)
Aseptic meningitis in 1% of symptomatic persons
Flaccid paralysis secondary to death of motor neurons is the dreaded complication of infection - 0.1% of all infections
Last indigenous case in U.S Last imported case 1993.

93. Polio Vaccination Oral Poliovirus (OPV) Vaccine
Attenuated viruses produced in cell culture
3 dose scheduled associated with life long immunity
VAPP a rare occurrence (1 per 750,000, 5-10 cases annually in US when OPV used).
No longer licensed in U.S.
Inactivated Poliovirus (IPV) Vaccine
Killed virus, not associated with VAPP.
Given in the U.S. in a 4 dose schedule

96. Nonpolio enteroviruses
Diverse clinical syndromes, often associated with predominant strain/serotype.

97. Hand foot and mouth syndrome
Classically associated with coxsackie A and enterovirus 71 (associated with neurologic disease).
Enterovirus 71 has been associated with large outbreaks of severe disease in young children
Neurologic disease includes meningitis, encephalitis, and myelitis
Also associated with pulmonary edema and hemorrhage
Fulminant sepsis like syndrome

98. Hand-foot and mouth disease

99. Hand-foot and mouth disease

100. Hand-foot and mouth disease