Lecture 10

Question 1

What are the two types of enteric viruses?

Answer 1

Enteroviruses and Gastroenteritis viruses.

Question 2

What is the difference between enteroviruses and gastroenteritis viruses?

Answer 2

Enteroviruses are a family of picornaviruses that do not cause gastrointestinal (GI) tract symptoms, while gastroenteritis viruses cause GI tract symptoms.

Question 3

What are the types of enteroviruses/picornaviridae?

Answer 3

Poliovirus (3 serotypes), Coxsackie A (23 serotypes), Coxsackie B (6 serotypes), Echovirus (31 serotypes), and Enterovirus (5 serotypes).

Question 4

What determines severity of enterovirus disease?

Answer 4

disease caused depends on the virus cytolytic capacity and tissue tropism, and antibody response.

Question 5

What are the characteristics of enteroviruses?

Answer 5

RNA, icosahedral virus, icosahedral virus with positive sense , Non-enveloped, faecal-oral, respiratory secretions, dust fomites transmission,

Question 6

How do enteroviruses infect cells?

Answer 6

Enteroviruses enter through the mouth and infect cells in the mucous membrane of the respiratory and GI tract.

Question 7

What happens during the primary viremia stage of enterovirus infection?

Answer 7

The virus spreads to other tissues and organs by the blood or nerves.

Question 8

What are the clinical outcomes of poliovirus infection in non-vaccinated people?

Answer 8

○ Asymptomatic- infection is limited to oropharynx and gut
○ Abortive poliomyelitis which happens due to viremia is nonspecific, causing fever, headache, vomiting etc and can resolve
○ Non-paralytic poliomyelitis (aseptic meningitis) which causes back pain and ,muscle spasms and usually subsides, considered as minor illness
○ Paralytic polio happens 3-4 days after minor illness. The virus can spread to the motor neurons in the anterior horn of the spinal cord and brain stem

Question 9

What is paralytic poliomyelitis?

Answer 9

Paralytic poliomyelitis is a cytolytic virus for motor neurons in the spinal cord and brain stem, causing asymmetrical flaccid paralysis, and is mainly caused by poliovirus type 1.

Question 10

What is the epidemiology of poliovirus infection?

Answer 10

It has an epidemiology of faecal-oral route in the summer/ autumn, and in endemic patterns, most children are infected by age 5.

Question 11

What are the two types of polio vaccines?

Answer 11

Oral polio vaccine (OPV) and inactivated poliovirus vaccine (IPV).

Question 12

What is oral polio vaccine?

Answer 12

Oral polio vaccine is live attenuated and is put in repeated passage through monkey kidney cells so it loses its neurotropism.

Question 13

What is trivalent OPV?

Answer 13

Trivalent OPV induces antibodies to each serotype and stops person-to-person transmission.

Question 14

How many doses of OPV do patients receive, and why?

Answer 14

Patients receive three oral doses of OPV at monthly intervals because the virus can mutate and become neurotropic, it can fail to immunize against all 3 serotypes, and vaccine strains can become the circulating strain.

Question 15

What is OPV-derived (OPVd) poliovirus?

Answer 15

OPV-derived poliovirus occurs when the weakened live poliovirus strains mutate and regain the ability to cause disease.

Question 16

What are the types of OPV-derived poliovirus?

Answer 16

Circulating vaccine-derived poliovirus (Cvdpv), immunodeficiency-related vaccine-derived poliovirus (IVDPV), and ambiguous vaccine-derived poliovirus (aVDPV).

Question 17

What is the Cvdpv?

Answer 17

Cvdpv is when vaccine strains become the circulating strains in grossly under-vaccinated communities

Question 18

What is IVDPV?

Answer 18

IVDPV is prolonged replication and excretion of vaccine strains due to the inability to mount an immune response and clear the vaccine strain from the intestines, causing prolonged exposure of the population to vaccine strains

Question 19

What is the method used to inactivate the polio virus in IPV vaccine?

Answer 19

The IPV vaccine is inactivated by formalin.

Question 20

What is the IPV vaccine made of?

Answer 20

The IPV vaccine uses supernatant from infected monkey kidney cells, inactivated by formalin.

Question 21

How many doses of the IPV vaccine are given to an individual?

Answer 21

The IPV vaccine is given in three doses to reduce the chances of transmission.

Question 22

Which muscles are affected by Coxsackie B?

Answer 22

Coxsackie B affects the heart and skeletal muscle.

Question 23

What are the phenotypes of Coxsackie B?

Answer 23

The three phenotypes of Coxsackie B are Pleurodynia, Myalgic Encephalomyelitis, and Myocardial and Pericardial Infections.

Question 24

What are the symptoms of Pleurodynia caused by Coxsackie B?

Answer 24

The symptoms of Pleurodynia caused by Coxsackie B are a sudden onset of fever, unilateral severe chest, and abdomen pain. Vomiting may occur, and it lasts approximately four days but may relapse.

Question 25

What is Myalgic Encephalomyelitis, and what is the link between it and Coxsackie B?

Answer 25

Myalgic Encephalomyelitis is a condition that mainly affects women and has no physical signs but many symptoms, including chronic fatigue. Coxsackie B4 is linked to this condition.

Question 26

Which age group has the highest incidence of viral meningitis?

Answer 26

Viral Meningitis has the highest incidence in children under 1 year old.

Question 27

What are the symptoms of Viral Meningitis caused by Coxsackie B and Echoviruses?

Answer 27

The symptoms of Viral Meningitis caused by Coxsackie B and Echoviruses are a sudden onset of fever, severe headache, photophobia, sore throat, cough, vomiting. It resolves spontaneously.

Question 28

Which virus causes acute haemorrhagic Conjunctivitis?

Answer 28

Coxsackie A24 and enterovirus 70 cause acute haemorrhagic Conjunctivitis.

Question 29

What are the clinical manifestations of gastroenteritis viruses?

Answer 29

The clinical manifestations of gastroenteritis viruses include damage to the epithelial lining and villi of the small intestine, leading to poor absorption of water and electrolyte imbalance.

Question 30

Which route is used for the transmission of gastroenteritis viruses?

Answer 30

Gastroenteritis viruses are transmitted through the faecal/oral route, person to person, contaminated food/water.

Question 31

What is the structure of Rotavirus?

Answer 31

Rotavirus has a non-enveloped, icosahedral capsid and 11 segments of double-stranded RNA.

Question 32

What is the most medically important Rotavirus group?

Answer 32

Group A is the most medically important Rotavirus group.

Question 33

What is the pathogenesis of Rotavirus?

Answer 33

The pathogenesis of Rotavirus includes the virus attaching to the surface of intestinal epithelial cells via its outer capsid proteins VP4 and VP7, entry of the virus, and replication of the viral RNA into viral proteins.

Question 34

What are the two names of live attenuated oral vaccines available for Rotavirus?

Answer 34

Rotateq and Rotarix.

Question 35

What type of virus is Norovirus?

Answer 35

Norovirus is a Caliciviridae, non-enveloped, positive-sense RNA virus.

Question 36

What is the incubation period of Norovirus?

Answer 36

The incubation period of Norovirus is 24-72 hours.

Question 37

What is the mode of transmission of Norovirus?

Answer 37

The mode of transmission of Norovirus is faecal/oral via person to person, directly via contaminated hands or the ingestion of contaminated food/water.