The document discusses viral gastrointestinal infections, specifically focusing on polio and echoviruses, which can be confined to the GI tract or spread to other body parts. It details the characteristics, transmission routes, and types of infections caused by these viruses, as well as prevention methods such as vaccines. Epidemiology data show that poliovirus is endemic in certain regions, while echovirus causes various opportunistic infections, particularly in children and immunocompromised individuals.

1. Viral gastrointestinal infections
(polio & echoviruses)
Submitted to Madam Saba Farooq
Submitted by: Shumailah Nayab
Roll # AP402818

2. Gastrointestinal infections
Infections caused by microorganisms in gastrointestinal
tract by the organisms which are not resident flora of
individual
These infections may be
 Confined to GI tract
Or
 initiated in the gut before spreading to other parts of
the body

3. Terms used in GI tract infections
 Gastroenteritis: inflammation of the stomach and intestines
rotaviruses, noroviruses
 Diarrhoea: a condition in which faeces are discharged from
the bowels frequently and in a liquid form rotaviruses,
caliciviruses, adenoviruses, parvoviruses
 Dysentery: inflammatory disorder of GI tract (large intestine)
associated with pus and blood in faeces
 Enterocolitis: inflammation involving the mucosa of intestines
enteroviruses, rotaviruses, Norwalk virus, adenoviruses

4. Enteroviruses
 genus of the family picornaviridae (70 serotypes)
 ss RNA,+ sense, naked virus with icosahedral symmetry
 stable to acid pH and resistant to lipid solvents since there is no envelope
 capsid has 60 copies each of 4 proteins, VP1, VP2, VP3 and VP4
 Enterovirus is divided into following groups
 Poliovirus
 Echovirus
 Coxsackievirus (a & b)

6. poliovirus
3 serotypes (distinct variations within a specie)
Humans are the only natural hosts for
polioviruses
Infection occurs via the faecal–oral route and
replication occurs in the alimentary tract
poliovirus infection is asymptomatic

7. Pathogenesis
 replication occurs in the alimentary tract
 Virus is shed in the faeces of infected individuals
 presence of viremia (virus in the bloodstream) occurs for
short time period

11. Subclinical infection
 in apparent subclinical
infection account for the vast
majority of poliovirus infections
 90 - 95% cases are subclinical
infections

12. Abortive infection
 4 - 8% cases are abortive infections
 virus spreads and replicates in other sites such as brown
fat, reticuloendothelial tissue, and muscles
 causes secondary viremia
symptoms
 fever
 headache
 sore throat

13. Paralytic poliomyelitis (Major illness)
 occurs in less than 1% of poliovirus infections
 virus enters the CNS and replicates in motor neurons within the spinal
cord, brain stem, or motor cortex
 cause the selective destruction of motor neurons leading to temporary or
permanent paralysis
 muscle pain and spasms are observed in paralysis
 it leads to respiratory arrest and death (rare)

14. How a gastrointestinal infection cause neurological
infection ????????
 This mechanism is poorly understood, but 3 hypothesis have been
suggested
primary viremia is required
1-virions pass directly from the blood into the central nervous system by
crossing the blood–brain barrier independent of CD155
2- virions are transported from peripheral tissues that have been bathed in the
viremic blood, for example muscle tissue, to the spinal cord through nerve
pathways via retrograde axonal transport
3- virus is imported into the CNS via infected monocytes or macrophages

15. Laboratory Diagnosis
Virus isolation:
 Cerebrospinal fluid usually show the changes typical for that of viral
meningitis with lymphocytosis and a high protein level
 molecular assays
 Specific sera neutralize the cytopathic effects, it can be identified
Serology:
 not widely used

16. Prevention
1. Inactivated Salk Vaccine:
formalin inactivated intramuscular polio vaccine (IPV)
It contains an injected dose of three antigenic strains of killed polio virus
2. Live Attenuated Vaccine:
live attenuated oral polio vaccine (OPV)
induces long lasting immunity
induces IgA formation

17. Epidemiology
 Polioviruses are disseminated globally
 densely populated developing countries, almost 100% of the
population have Abs to all 3 types of the virus before 5 years of age
 Epidemics do not occur and paralytic disease is rare as the
incidence of paralytic poliomyelitis increases with age, especially
after 15 years of age
 Pakistan is one of three countries in the world where poliomyelitis is
still categorized as an endemic viral infection

18. ECHOvirus
 enteric cytopathic human orphan (ECHO) virus
 largest Enterovirus subgroup, 34 serotypes
 Cause opportunistic infections and diseases
 faecal-oral transmission
 its primary target is children and immuno compromised
people
 resistant to pH (3-10) and are ether and alcohol

19. pathogenesis
 replication begins in the pharynx or gut (M cells) after ingestion of
contaminated material
 virus spread to regional lymph nodes and cause subclinical transient
viremia, spread to liver, spleen, bone marrow, and distant lymph nodes
 Secondary sites of infection include the CNS, liver, spleen, bone marrow,
heart, and lungs

20. Epidemiology
 associated with both epidemic and endemic patterns of infection
 Infection rates vary with the season, geography, and the age and
socioeconomic status of the population
 Echovirus 9 was the most commonly reported enterovirus from 1970-2005
and accounted for 11.8% of reports with known serotypes
 Epidemics have been reported in Panama, Mexico, Switzerland, Cuba, the
United States, and Turkey. Asian-Pacific countries have reported major
enteroviral epidemics with significant morbidity and mortality

21. Diseases caused by echovirus
 Acute aseptic meningitis
 Encephalitis
 Rash
 Respiratory illness
 Herpangina
 Epidemic pleurodynia (Bornholm disease)- disease of muscle
 Paralysis
 Myocardial/pericardial disease

22. Vesicular rashes
 lesions on the head, trunk, and extremities
 do not progress to pustules and scabs
 Petechial and purpuric rashes have been reported with echovirus 9
 When these rashes have a haemorrhagic component (flow of blood ), the illness
can be confused with meningococcal disease, particularly when aseptic
meningitis occurs

23. Laboratory Diagnosis
Virus Isolation from
 faecal samples
 from the pharynx during the acute phase of the illness, especially in cases
with respiratory infections
Serological Techniques
 Neutralization tests are generally the best serological tests available
Direct detection of viral genomes
 PCR assays are becoming increasingly used

24. Prevention
 Vaccination is not available
 only effective measures for their control are
high standards of personal and community
hygiene

25. References
 Acute Poliomyelitis at eMedicine Pediatric Poliomyelitis at eMedicine
 Charles Chan and Roberto Neisa. "Poliomyelitis". Brown University.
 ped/629 at eMedicine
 Ryan KJ; Ray CG, ed. (2004). Sherris Medical Microbiology (4th ed.).
McGraw Hill. pp. 537–9. ISBN 0-8385-8529-9.
 Yin-Murphy M, Almond JW (1996). Baron S; et al.,
eds. Picornavirues. in:Baron's Medical Microbiology (4th ed.). Univ of Texas
Medical Branch. ISBN 0-9631172-1-1.
 The facts about enterovirus D68". http://www.childrensmn.org/. Children's
Hospitals and Clinics of Minnesota.

26. Any question?????????