1. Viruses Associated with Gastroenteritis
Ghazi Jamjoom

2. VIRAL AGENTS CAUSING GASTROENTERITIS

3. VIRAL AGENTS CAUSING GASTROENTERITIS
Major Viruses
Rotavirus
Enteric adenoviruses
Noroviruses :
a. Norwalk-like viruses
b. Calicivirus
c. Astrovirus

4. Noroviruses Norwalk-like Caliciviruses Astroviruses other
viruses viruses

5. Viruses associated with gastroenteritis (cont) :
Other viruses (minor):
Coronaviruses
Parvoviruses
Pestiviruses
Toroviruses

6. Family Reoviridae Genus Rotavirus

7. ROTAVIRUS First isolated in 1973 from children with diarrhea
EM identification from duodenal biopsies
Human and animal strains

8. Rotavirus

9. Rotavirus- EM Structure

10. ROTAVIRUS 60-80nm in size Non-enveloped virus Double capsid
EM appearance of a wheel with radiating spokes
Icosahedral symmetry
double stranded (ds) RNA in 11 segments
(double – double)

11. STRUCTURE Double capsid (outer and inner capsid) Core with genome
Capsid is cleaved by trypsin to form
ISVP- infective sub-viral particle

12. ROTAVIRUS- 3D STRUCTURE

13. ROTAVIRUS- ultrastructure

14. Rotavirus- details of EM structure

15. Viral Structural Proteins (VP)
Outer structural proteins - VP7 and VP4
VP7=glycoprotein
VP4=protease-cleaved, P protein, viral hemagglutinin, and forms spikes from the surface
Inner core structural proteins VP 1, 2, 3, 6
VP6 is an important antigenic determinant

16. which (groups A, B, and C) infect humans .
Genome is composed of 11 segments of double-stranded RNA,
six structural
coding for proteins
five nonstructural
Seven serological groups have been identified (A-G), three of
which (groups A, B, and C) infect humans .

17. STRUCTURE

18. Gene coding assignment

19. Classification
Groups, subgoups, serotypes based on viral capsid proteins
7 Groups (A through G)
Group A is the most common and has 2 subgroups
10 human serotypes based on G protein (VP 7)
8 P protein serotypes

20. Classification (contd.)
Electropherotypes
mobility of RNA segments by PAGE
Used in epidemiologic studies

22. Rotavirus - Properties
Virus is stable in the environment
Relatively resistant to handwashing agents
Susceptible to disinfection with 95% ethanol, ‘Lysol’, formalin

23. Pathogenesis
Targeted host cells- mature enterocytes lining the tips of intestinal villi
Intermediate/infective sub-viral particle (ISVP) produced through proteolysis
Enter host cell by endocytosis
Virus replicates in the host cell cytoplasm

24. Replication mRNA transcription with viral RNA polymerase
Capsid proteins formed
mRNA segments formed, assembled into immature capsid
mRNA replicated to form double stranded RNA genome

25. Histopathology
Mature enterocytes lining the tips of intestinal villi are affected
Villous atrophy and blunting
Death of the mature enterocytes

26. Histopathology Infiltration of lamina propria with mononuclear cells
Repopulation of the villous tips with immature secretory cells [crypt hyperplasia]

27. Histopathology

28. Epidemiology - Worldwide
Millions are affected
600, ,000 deaths/year
A major cause of diarrhea-associated hospitalizations
Seroprevalence studies show that antibody is present in most by age 3y.

29. Rotavirus- Worldwide distribution (source- centers for disease control and prevention)

30. Estimated Global Distribution of The 800,000 Annual Deaths
Caused By Rotavirus Diarrhea

31. Epidemiology : U.S. No. of children under 5y. affected ~ 2.7 million
Physician visits per year ~ 500,000
Hospitalizations per year ~ 50,000
Deaths per year ~
% cases w/ dehydration ~ 1-2.5%

32. Epidemiology
Age- 4mo - 2 years Protection of younger infants through transplacental antibody transfer
Asymptomatic infections are common, especially in adults
Nosocomial infections
Outbreaks

33. Epidemiology (contd.) Seasonality
Winter months (Nov. through May in US)
Gradual spread W to E
Year-round in the tropics
Incubation period - thought to be <4 days

34. Epidemiology : U.S. (Source- centers for disease control and prevention)

35. Spread in the U.S. (Source- centers for disease control and prevention)

36. Epidemiology (transmission)
Mainly person to person via fecal-oral route
Fomites
Food and water-borne spread is possible
Spread via respiratory route is speculated

37. Epidemiology (spread)
Contagious from before onset of diarrhea to a few days after end of diarrhea
Large amounts of viral particles are shed in diarrheal stools
Infective dose is only pfu

38. EPIDEMIOLOGY Differences in Groups
Group A infections are most common
Group B has been associated with outbreaks in adults in China
Group C is responsible for sporadic cases of diarrhea in infants around the world

39. Clinical Features Incubation period - thought to be <4 days
Fever- can be high grade (>102F in 30%)
Vomiting, nausea precede diarrhea
Diarrhea
- usually watery (no blood or leukocytes)
- lasts 3-9 days
- longer in malnourished and immune deficient indiv.
- NEC and hemorrhagic GE seen in neonates

40. Mechanism of diarrhea
Watery diarrhea due to net secretion of intestinal fluid
Activation of the enteric nervous system -possible role of enterotoxin

41. Clinical Features (contd.)
Dehydration is the main contributor to mortality.
Secondary malabsorption of lactose and fat, and chronic diarrhea are possible

42. Recovery is usually complete.
However, severe diarrhea without fluid and electrolyte
replacement may result in dehydration and death .

43. Immunological Aspects
Immunoglobulin (Ig) A , in the lumen of the gut immunity
to infection .
Actively or passively acquired antibodies (including antibodies in
colostrum and mothers milk) lessen the severity of disease
but does not consistently prevent reinfection .
Absence of antibody small amounts of virus infection
and diarrhea .

44. Diagnosis
Antigen detection in stool by ELISA, Latex Agglutination (for Group A rotavirus)
EM- non-Group A viruses also
Culture- Group A rotaviruses can be cultured in monkey kidney cells
Serology for epidemiologic studies

45. Treatment and Prevention
Supportive - oral, IV rehydration
Prevention-
Handwashing and disinfection of surfaces

46. Vaccine Live tetravalent rhesus-human reassortant vaccine (Rotashield)
Licensed for use in August 1998
Removed from the market in October 1999 due to risk of intussusception
Cases were seen 3-20 days after vaccination
Approx. 15 cases/1.5 million doses
New vaccine from bovine rotavirus under trial

47.                                                                 
Production of rhesus rotavirus (RRV), human rotavirus (HRV) x rhesus rotavirus (RRV)reassortant quadrivalent vaccine wit VP7 serotype 1, 2, 3, and 4 specificity

48. GASTROENTERITIS DUE TO ENTERIC ADENOVIRUS

49. GASTROENTERITIS DUE TO ADENOVIRUS
Types 40, 41
Belong to serogroup F
Some cases due to types 31, 3, 7

50. Diarrhea due to Enteric Adenovirus
Age <4 years
Year round
Spread via fecal-oral route

51. Clinical features of Enteric Adenovirus gastroenteritis
Incubation period days
Diarrhea lasts for days
Can also cause intussusception, mesenteric adenitis, appendicitis

52. Diagnosis- Enteric adenoviruses
Isolation requires special media-Graham 293
ELISA for rapid detection is available

53. HUMAN CALICIVIRUSES

54. HUMAN CALICIVIRUSES (HuCV)
Belong to Family Caliciviridae
Non-enveloped RNA viruses
with ss RNA
27-35 nm in size
Contain a single capsid protein

55. HUMAN CALICIVIRUSES Genomic analysis divides it into 4 groups
Human caliciviruses belong to 2 genera

56. CLASSIFICATION OF HuCV
NLV (Norovirus)
Norwalk virus
Hawaii virus
Snow Mountain virus
Montgomery county virus
Taunton (England)
SLV (Sapovirus)
Sapporo virus
Manchester virus
Houston/86
London/92

57. Morphology of HuCV- typical
Typical morphology
32 cup-like depressions
EM appearance of “Star of David”
E.g.- Sapporo-like viruses

58. HUMAN CALICIVIRUSES - SLV

59. Morphology of HuCV- atypical
Atypical morphology
Smooth surface
Small Round Structured viruses
E.g.- Norwalk-like viruses

60. SRSV- NORWALK VIRUS

61. CLINICAL FEATURES Adults and Children
Usual incubation Period is <24 hours
(ranges from 12hrs. to 4 days)
Short duration of illness <3 days
Nausea, vomiting, fever, headache
Abdominal cramping
Watery diarrhea

62. Epidemiology-Noroviruses
Worldwide distribution
>23 million cases/year in the U.S.
Major cause of foodborne outbreaks of GE
Most people have had infections by age 4 years (by seroprevalence studies)

63. Spread of Norwalk virus
Person-to-person Fecal-oral spread (stool/vomitus)
Fecal contamination of food or water
Spread through fomites?

64. Epidemiology-Noroviruses
Asymptomatic infections- seroconversion but asymptomatic shedding of virus
Low infective dose
Viral excretion during convalesence
(up to 2 weeks)
Ability to survive in water chlorination at
routine levels

65. Epidemiology of Outbreaks
Cruise ships, schools, nursing homes, etc.
Can involve infants and school-age children
Source usually is contaminated food and water (seafood-oyster and shellfish etc.)

66. Diagnosis- Human Caliciviruses
Specimen- stool , vomitus, environmental swabs, [not yet on foods]
Immune EM
RT-PCR in state public health labs.
Serology for epidemiologic purposes

67. HUMAN ASTROVIRUS

68. ASTROVIRUS
Described in relation to an outbreak of gastroenteritis in 1975
Detected by EM
Immunologically distinct from Human Caliciviruses
Belong to family Astroviridae
8 human serotypes are known

69. ASTROVIRUS- structure
Small ss RNA virus
Non-enveloped
27-32nm in size
Round with an unbroken, smooth surface
EM appearance of a 5 or 6 pointed star within smooth edge
Contain 3 structural proteins

70. ASTROVIRUS- EM STRUCTURE

71. ASTROVIRUS - Epidemiology
Worldwide
Mainly in children <7 years of age.
Transmission person-to-person via
fecal-oral route
Outbreaks due to fecal contamination of
sea-food or water

72. ASTROVIRUS - Clinical Features
Infants and children are most often affected
Short incubation period 1-4 days
Nausea, vomiting, abdominal cramping and watery diarrhea
Constitutional symptoms-fever, malaise, headache

73. ASTROVIRUS - Diagnosis
EM (virus shed in stool in great numbers)
EIA
RT-PCR

75. Rotaviruses
Ghazi Jamjoom

76. Twenty-five years ago, little was known about the causes of diarrhea, which kills an estimated 3 million infants and children
worldwide every year.
Scientists knew that bacteria and parasites were implicated in only approximately 10 to 20 % of all cases of diarrhea..

77. In 1973,, researchers in Australia discovered a virus in infants with severe diarrhea and named it “rotavirus” for its wheel-like shape.
One year later, NIAID researchers were the first to identify rotavirus in the United States.

78. Rotavirus Biology Rotaviruses belong to the family Reoviridae ,
genus Rotavirus.
They have a characteristic wheel-like
appearance when viewed by electron
microscopy.
Nonenveloped, double-shelled

81. Endemic worldwide (represents > 95% of
Group A rotaviruses
Endemic worldwide (represents > 95% of
currently identified strains in humans )
The leading cause of severe diarrhea among
infants and children .
Accounts for about half of the cases
requiring hospitalization.

82. Group B rotavirus, Also called adult diarrhea rotavirus or ADRV
Has caused major epidemics of severe
diarrhea affecting thousands of persons
of all ages in China.

83. Group C rotavirus cases of diarrhea in children in many countries.
Has been associated with rare and sporadic
cases of diarrhea in children in many
countries.
First outbreaks were reported from Japan
and England

84. Subgroups classification based upon neutralization epitopes of the outer capsid proteins, VP4 and VP7
Antigenic specificity of VP7
G serotypes
Antigenic specificity of VP4
P serotypes
Fourteen G serotypes and twenty one P serotypes have been detected in humans.
Neutralization assays measure reactivity predominantly to VP7 proteins.

85. Distribution of Rotavirus Strains From A Global Collection of 2,748 Strains.

86. Transmission Rotavirus infection is very contagious .
Viral particles pass in the stool of infected persons before and after they have symptoms of the illness .
Spread is by the oral-fecal route

87. The virus can survive for long periods on hard surfaces (e.g.
toys and tables) and is not killed by standard
disinfectants... children forget to wash their hands often
enough, especially before eating and after using the toilet.
toilet Get infected
Infected food handlers may contaminate foods that require
handling and no further cooking, such as salads, fruits.

88. The infective dose is presumed to be 10-100 infectious viral particles
The infective dose is presumed to be infectious viral particles Because a person with rotavirus diarrhea often excretes large numbers of the virus ( infectious particles/ml of
feces), infection doses can be readily acquired .

89. Asymptomatic rotavirus excretion has been well documented may play a role in perpetuating
endemic disease .
N.B some have reported low titers of virus in respiratory
tract secretions and other body fluids..

90. Epidemiology

91. Affects approximately 130 million infants and children worldwide.
Rotavirus is the single most important cause of life-threatening diarrhea in children younger than 2 years.
Affects approximately 130 million infants and children worldwide.
In the United States alone, rotavirus causes more than 3 million cases of childhood diarrhea each year, leading to an estimated 55,000 to 100,000 hospitalizations and 20 to 100 deaths.

92. When do people get infected ?
In the United States, rotavirus causes outbreaks of diarrhea
during the winter months.
In temperate areas, it occurs primarily in the winter.
In the tropics it occurs throughout the year.

93. Who catch the infection ?
Humans of all ages are susceptible to rotavirus infection,
although Children , premature infants, the elderly,
and the immunocompromised are prone to more severe symptoms caused by infection with group A rotavirus.

94. An infant’s first bout of diarrhea from rotavirus is the most severe , subsequent reinfections decrease in severity. These findings indicated that infants gradually develop partial immunity to the virus and that a vaccine might prevent the disease.

95. Rotavirus can survive in the acidic environment , in a buffered
Pathogenesis
Rotavirus can survive in the acidic environment , in a buffered
stomach , or in a stomach after a meal.
Virus adsorption to columnar epithelial cells
viral replication
shortening and blunting of the microvilli and mononuclear cell infiltration into the lamina propria

96. NSP4 protein may act in a toxin-like manner
Temporary lactose intolerance may occur.
NSP4 protein may act in a toxin-like manner
Neuronal alteration in water absorption
Release of neuronal activators
Calcium ion influx into enterocytes
Loss of the ability to absorb water net secretion
of water and loss of ions watery diarrhea

97. Watery diarrhea dehydration (most commonly
isotonic) and may lead to metabolic acidosis and
death .

98. Some may have a slight rise in temperature .
Symptoms and Signs
The incubation period ranges from 1-3 days .
Symptoms often start with vomiting followed by 4-8 days of
diarrhea.
Some may have a slight rise in temperature .

99. Immunological Aspects
Immunoglobulin (Ig) A , in the lumen of the gut immunity
to infection .
Actively or passively acquired antibodies (including antibodies in
colostrum and mothers milk) lessen the severity of disease
but does not consistently prevent reinfection .
Absence of antibody small amounts of virus infection
and diarrhea .

100. Infection in infants and small children is generally symptomatic .
In adults infection is usually asymptomatic .
Asymptomatic rotavirus infections are common in neonates
because of passively acquired maternal immunity , breast
feeding , and possible infection with less virulent strains

101. Diagnosis
(EIA)
1) Identification of the viral antigen in the patient's stool
latex agglutination
most widely used screening test for clinical specimens .
2) Electron microscopy (EM)
3) polyacrylamide gel electrophoresis (PAGE) is used in some laboratories for RNA typing.
4) A reverse transcription-polymerase chain reaction (RT-PCR) has been developed to detect and identify all three groups of human rotaviruses.

103. Serotypes can be identified using monoclonal antibodies
against VP7 and VP4.
Neutralization is detected on tissue cultures as a CPE
Antigenic specificity of VP G serotypes
Antigenic specificity of VP P serotypes

104. Treatment Treatment is nonspecific and consists of :
1) Oral rehydration therapy to prevent dehydration.
2) About one in 40 children with rotavirus gastroenteritis will
require hospitalization for intravenous fluids .
For persons with healthy immune systems, rotavirus gastroenteritis is
a self-limited illness, lasting for only a few days.

105. prevention
Even in the cleanest environments with the best hygiene, most children
still become infected with rotavirus before age 4 or 5.
Total prevention of the spread of rotavirus is virtually impossible.
In hospitals health officials control rotavirus outbreaks by isolating
infected patients and by ordering strict hand-washing procedures.

106. Rotavirus
Vaccine

107. Rotavirus vaccine
Scientists knew that although many strains of rotavirus exist, only four
cause the majority of diarrhea cases in young children in the United
States.
Aiming for prevention : NIAID researchers developed a vaccine
(RRV-TV) designed to protect against the four strains of rotavirus .

108. During the 1970s, NIAID scientists analyzed the genetic material of
rotavirus, Identified two important proteins , VP4 and VP7 produced
by the genes , and determined the function of these proteins.
Proteins on the surface of the virus were found to be critical for triggering
an immune response in the body against rotavirus.
NIAID researchers focused on these proteins to develop a vaccine.

109. Tetravalent Oral Live-Attenuated Vaccine
The oral vaccine contains four different, live attenuated viral strains,
serotypes ( 1,2,3,4) .
One strain (serotype 3) is an unmodified rhesus monkey rotavirus
(RRV) which does not cause disease in humans
The other three are made by reassortment (genetic recombination)
of that monkey RRV with three human rotaviruses of serotypes
1,2,4.

110. Each reassortant vaccine strain contains 10 monkey RRV genes and
the VP7 gene for one serotype of the human rotavirus envelope
proteins:
VP-7 (serotype 1) , VP-7 (serotype 2) , VP-7 (serotype 4)
The combined vaccine provided comprehensive protection
against the four serotypes (1,2,3,4)

111. Studies showed that high doses of the RRV-TV vaccine, designed to
protect against four strains of rotavirus, were very effective in
preventing severe, dehydrating rotavirus disease.
Breast-feeding did not interfere with the effectiveness of
the rotavirus vaccine ensuring good nutrition in infants

112. In August 1998, the first live attenuated rotavirus vaccine (Rotashield{registered} {Wyeth Lederle Vaccines and Pediatrics}) was approved for use in infants by the Food and Drug Administration. The Advisory Committee on Immunization Practices has recommended that this vaccine be given as a three-dose schedule to infants aged 2, 4, and 6 months.

113. Why? However, on July 15, 1999, the US Centers for Disease Control and
Prevention (CDC) recommended that doctors stop giving the
rotavirus vaccine to infants.
On October 22, 1999, the Advisory Committee on Immunization
Practices voted to stop recommending the vaccine
Why?

114. Centers for Disease Control and Prevention (CDC) advisory committee
received an overwhelming amount of data all indicating a strong
association between ( rotavirus vaccine ) and bowel obstruction among
some infants during the first one to two weeks following vaccination.
Apparently, many infants who received the rotavirus vaccine developed
Intussception of the bowel within one to three weeks after receiving
a dose or two of the vaccine.

115. Medline Search
Oct. 15, a total of 102 confirmed and presumptive cases of intussusception following receipt of << rotavirus vaccine>> were reported to the Vaccine Adverse Events Reporting System (VAERS). 57 had onset within seven days of receipt of the vaccine and 29 underwent surgery; seven required bowel resection. One fatal case was reported in a 5-month-old, according to John Livengood, MD, director of the Epidemiology and Surveillance Division, National Immunization Program, CDC.

116. The risk of intussusception was increased 19-fold in the first 3 to 7
days after vaccination and almost fourfold (3.6) in the 8 to 14 days
after vaccination (P<0.0002).

117. These data indicate that the risk of intussusception is increased by 80% after rotavirus vaccination in an ever vs. never comparison. For dose one, the risk of intussusception increased 25-fold in the first three to seven days following vaccination and 7.1-fold in eight to 14 days after vaccination. For dose two, the risk of intussusception increase 13.4-fold in three to seven days after rotavirus vaccination.

118. problems do not appear to be at risk now.
Children who have already received the vaccine and have not had
problems do not appear to be at risk now.
In the meantime, research on better vaccines for rotavirus
continues.

119. Vaccine adverse reactions

120. Percentage of children with adverse reactions during 5 days of surveillance following each of three doses of tetravalent rhesus-rotavirus vaccine (RRV-TV) or placebo.
percentage with fever (as measured by axillary temperatures).*On day 4, 2.2% of RRV-TV recipients vs. 0.2% of placebo recipients became febrile (p = 0.02).
b) percentage with diarrhea.
c) percentage with vomiting. Adapted from (43).

121. following receipt of doses 1, 2, or 3 of RRV-TV
following receipt of doses 1, 2, or 3 of RRV-TV. The number of children who have received RRV-TV is unknown, however, the observed rate of intussusception among vaccine recipients during the first 3 weeks after immunization appears to be greater than expected, with the highest rate during the first week following vaccination. These initial data suggest that intussusception occurs at a younger age in vaccine recipients than in unvaccinated children.

122. Prevention: In 1998, the U.S. Food and Drug Administration approved a live virus vaccine (Rotashield) for use in children. However, the Advisory Committee on Immunization Practices (ACIP) recommended that Rotashield no longer be recommended for infants in the United States because of data that indicated a strong association between Rotashield and intussusception (bowel obstruction) among some infants during the first 1-2 weeks following vaccination.  More information about rotavirus vaccine is available from the National Immunization Program
Sanitary measures adequate for bacteria and parasites seem to be ineffective in endemic control of rotavirus, as similar incidence of rotavirus infection is observed in countries with both high and low health standards

124. Rotavirus
Infection at
KAAUH ?

125. A 1293 fecal samples were collected
from patients of different age groups
with gastroenteritis over a period of
6 years & 8 months (November 1995
– July 2002) in Jeddah.

126. 708 males (54.76%)
1293
585 females ( 45.24%)
All were tested using enzyme linked immunosorbent
assay (ELISA).

127. Number of infected patients 136
73 males (53.68%)
63 females (46.32%)
5.65% males
% of infected patients 10.52
4.87% females

128. % of infected males = %
% of infected females = %

129. Statistics

130. N=127
(total number of patients between 0 years - 40 years)
Mean = 2.69 years
Std.Error= .4590

131. Descriptive Statistics
N=127(total number of patients between 0 years-40 years)
Mean = 2.69 years
Std.Error= .4590

132. Distribution of Age of Patients
5.7
(years)

133. Numbers of Infected Males to Females in Different Age Groups
0-28
28d-1y
1-3
3-6
6-18
>18

135. Distribution of Age of Patients Excluding The Out-Liers
(years)

136. Infected Saudies : non Saudies

137. Infections Among Males : Females (saudies : non saudies)

138. Infections in( Males : Females ) in Different Seasons

139. Infections of males to females in different seasons

140. Infections in Males in Different Seasons : Infections in Females in Different Seasons

142. Duration of Illness
(days)

143. Numbers of patients from different Age Groups ( Males to Females )

144. Number of Patients in Different Seasons (Males : Females )

145. Number of Patients in Different Seasons (Males : Females )

146. Number of Infected Males & Females in Each Nationality

147. Infections Among Different Nationalities in Each Season

148. Distribution of Different Durations of Illness
(days)

149. Means of Infections Among Different Age Groups

150. conclusion Rotavirus was found to be most prevalent among
infants and young children .
There is no significant difference in incidence
depending on the sex.
Most of the cases were presented to the hospital in the
winter.
The mean duration of illness is 3.3 days, with the
majority having symptoms of gastroenteritis for 3-5 days.

151. Saudi &non

152. Saudi & non
T-test