15: Acute Infection Flashcards
Which viruses cause acute infection?
- Influenza virus
-Poliovirus - Norovirus
- Measles virus
- West Nile virus
What are the characteristics of an acute infection?
- Rapid onset of viral production
- Severe course of disease
- Generation of large numbers of virus particles
- Virus is cleared and infection is resolved
What are inapparent (asymptomatic) acute infection?
- Successful infection with no symptoms
- Sufficient virus particles produced during infection to promote the spread
- Recognize infections accidentally during outbreaks
ex. 90% of polio infections are asymptomatic
ex. 40% covid are asymptomatic
How is influence virus transmitted?
What are the symptoms?
What are complicated diseases?
It is transmitted by coughing, sneezing and contact with contaminated surfaces touch eyes/ nose
Symptoms: headache, malaise, fever, loss of appetite, cough/sore throat
Test: PCR
It is an endemic disease (seasonal & occurs every year)
Primary viral pneumonia, secondary bacterial pneumonia, muscle pain
What are the sites of influenza virus entry in the respiratory tract?
A layer of mucus is produced by goblet cells and virus particles that pass through this layer reproduce in ciliated epithelial cells in the mucosal epithelium or the basement.
How are measles transmitted? What are the symptoms for measles?
- It is trasmitted via respiratory droplets
- contagious rash for 2-3 days
- once infected, lifelong immunity
Symptoms: fever, dry cough, sore throat, red patchy rash, Kopliks spots
How do infected Individuals shed the virus particles for measles?
Virus particles infect immune cells such as dendritic cells and macrophages. Then they travel via lymphatics to reach the blood which then reach target organs (brain & skin). In the brain it causes encephalitis and in the skin it causes a rash.
Virus reinfects through respiratory epithelium
What is the incubation period and prodromal of measles virus?
0-8 days: Primary viremia and secondary viremia
8-14 days: virus shedding, kopliks spots and fever/malaise
14-20 days: continued shedding and antibody production
What are complications that can occur due to measles?
- Pneumonia + bronchitis
- Subacute sclerosing panencephalitis (SSPE)
- Immunosuppression
- Mortality rate 1-2/1000
How is poliovirus transmitted and infects?
- Fecal-oral transmission
- Reproduced in oropharynx and intestine
- shedding in feces
- 1% cases, virus particles can reach motor neurons via blood and reach muscle. This causes retrograde transmission which infects motor neurons causing paralysis
What is the transmission and infection of norovirus?
Symptoms, Incubation period
- Causes 58% of all gastroenteritis in US
- Fecal oral tranmission
- Reproduces in the intestine, shedding in the feces
Symptoms: stomach pain, diarrhea, and vomitting
Incubation period: 10-50 hrs
Virus shedding can persist for 56 days
Short-term immunity: Reinfection can occur later in life
No vaccine 200,000 deaths
What is the west-nile virus?
- It is isolated from west-nile district in Uganda
- Mosquito borne virus
- Virus infect mosquito and birds and human are dead end
- Flu-like illness
Causes:
headache, muscle weakness, cognitive impairment, polio-like paralysis, 10% mortality
Which viruses are neuroinvase?
- Rabies, polio, measles and west nile
