VIRAL & FUNGAL INFECTIONS OF
GIT
Assist Prof Dr.
Syed Yousaf Kazmi
OBJECTIVES
• Major Viruses & Fungi that cause
gastrointestinal diseases, their epidemiology,
etiology, pathogenesis
• Mechanism of transmission; Enlist clinical
conditions
• Laboratory diagnosis of these infections
VIRAL INFECTIONS OF GIT
• Viral Gastroenteritis
– Rotavirus
– Astrovirus
– Adenovirus
– Calicivirus
• Viral Hepatitis
– Hepatitis A
– Hepatitis E
Electron microscopy of Rotavirus
ROTA VIRUS
• Rotaviruses-major cause of diarrhea
in infants
• Adult also infected
• Non-enveloped RNA Virus
• Various serotypes A, B, C
• Rotaviruses infect cells in the villi of
the small intestine (gastric and
colonic mucosa are spared
• Multiply in the cytoplasm of
enterocytes
• Damaged cells slough into the lumen
• Large quantities of virus in stool
• Viral excretion usually lasts 2–12 days
in otherwise healthy patients
ROTA VIRUS-EPIDEMIOLOGY &
CLINICAL PRESENTATION
• Single most imp worldwide cause of
gastroenteritis in young children
• 50% of Acute GE of hospitalized
children throughout the world
• Between ages 6 months and 2 yrs
• Incubation period of 1–3 days
• Watery diarrhea, fever, abdominal
pain, vomiting, leading to
dehydration
• Severe loss of electrolytes & fluids
may be fatal
• Transmission by the fecal–oral route
• Local immunity e.g. secretory IgA
hospitalization of infants and young
children with severe diarrhea
OTHER VIRUS CAUSING
GASTROENTERITIS
VIRUS
EPIDEMIOLOGY
IMP CAUSE OF
HOSP
Enteric
Second most important viral agent of endemic Yes
adenovirus diarrheal illness of infants and young children
worldwide
Caliciviruses Important cause of outbreaks of vomiting and No
(Norovirus) diarrheal illness in older children and adults in
families, communities, and institutions;
frequently associated with ingestion of food
Astroviruses Sporadic cases and occasional outbreaks of
No
diarrheal illness in infants, young children, and
the elderly
LABORATORY DIAGNOSIS
• Electron microscopy (EM)
• Immune electron
microscopy (IEM)
• Detection of viral antigen
by ELISA more sensitive
than IEM
• PCR of viral genome most
sensitive (Rotavirus)
• Serology- IgG and IgM
antibodies against viral
antigens
VIRAL HEPATITIS
• Hepatitis A virus & Hepatitis
E virus
• Both transmitted-fecal oral
route (water, food)
• Non enveloped virus
• HAV stable to treatment
with 20% ether, acid (pH 1.0
for 2 hrs), heat (60°C for 1 hr)
• Virus is destroyed by
autoclaving (121°C for 20
minutes), by boiling in water
for 5 minutes
• HEV- usually epidemic form
VIRAL HEPATITIS-PATHOGENESIS &
EPIDEMIOLOGY
• Acute hepatitis
• HAV inf usually asymptomatic,
mild fatigue, vomiting, nausea,
mild jaundice in children
• In adult signs & symptoms of
icteric, fever
• HAV no carrier state, mortality
<1%
• HEV –acute hepatitis in
epidemics
• No carrier state
• HEV-Association of high
mortality in pregnant ♀(30-40%)
VIRAL HEPATITIS- LAB DIAGNOSIS
• LFTs-deranged
• IgG & IgM antibodies in
serum by ELISA (HAV &
HEV)
• Liver biopsy for H/P
• Viral genome by PCR
• Electron microscopy
FUNGAL INFECTION OF GIT
• Pseudomembranous
Candidiasis of upper &
lower GIT
– Oral thrush
– Candida esophagitis in HIV
– Colitis
• Invasive Aspergillosis
(rare)
Oral thrush in leukemic patient
FUNGAL INFECTION OF GIT
• Opportunistic fungal
infection
• Candida is normal flora of
GIT
• Cell mediated immunity
impairment
• Overgrowth of Candida
• Associated with use of
broad spectrum
antimicrobials
FUNGAL INFECTION –LAB DIAGNOSIS
Gram stain of
Candida albicans
Candida on Sabouraud Agar
• Gram Stain of
scrapping
• Culture on Sabouraud
agar
• Biochemical
identification
MCQ
A 57-years-old patient who is suffering from Hodgkins
Lymphoma presents with pain & swelling of tongue. On
examination, white curdy patches were noted on tongue.
Gram stain of the scrapping revealed Gram positive
budding structure. Which of the following cell structure
will be missing in this organism?
a. Cell membrane
b. Mitochondria
c. Nuclear membrane
d. Cell wall peptidoglycan
e. Ribosome
MCQ
A 32-years-young pregnant lady developed yellow
discoloration of sclerae, nausea, vomiting and abdominal
pain. Patient died on third day of hospital admission. If
the etiological agent has fecal oral route of transmission,
which of the following agent is most likely cause of her
illness?
a. HAV
b. HBV
c. HCV
d. HDV
e. HEV
THANK YOU