T1-L2: Viral and Prion Pathogens Flashcards
What virus establishes latency in the sensory nerve ganglion of the trigeminal nerve and periodic reactivation relate to cold sores?
HSV-1. The virus exists in 805 of the UK population. It leads to:
- Vesicles and ulcers - typically in the mouth. Can also be found in the genitals
- Encephalitis - the most common viral cause of encephalitis worldwide.
What virus establishes latency in the sensory nerve ganglia on the sacral ganglia and periodic reactivations occur in the genital area?
HSV-2. Clinical manifestations include:
- Vesicle/ulcers - to skin or mucous membranes typically of the genitals/buttocks
- Meningitis
- Neonatal herpes - occurs through vertical transmission. It is life-threatening
What virus reactivates as Shingles?
Varicella Zoster Virus. Its primary infection is Chicken pox and it reactivates causing unilateral vesicles in a dermatonmal distribution as Shingles. Latency is established in the dorsal root ganglia of the whole CNS. 95% of children have had chicken pox by the age of 20. It is spread via respiratory droplet transmission.
What virus causes 80% of infectious mononucleosis?
Epstein Barr Virus (Glandular Fever or Infectious Mononucleosis). Virus is shed in saliva and genital secretions.
It establishes latency in the B cells most commonly in those who are unwell or immunosuppressed. It has a strong association with malignancy as it is an oncogenic virus.
What virus establishes latency in myeloid progenitor cells/monocytes and dendritic cells and has a primary infections of infectious mononucleosis?
Cytomegalovirus. It can lead to congenital CMV infections when infants acquire this when mothers are infected in pregnancy. It can lead to retinitis, deafness, microcephaly, hepatosplenomegaly in the neonate. Reactivation in immunosuppressed patients can lead to retinitis, colitis and pneuomintis.
What is the most common cause of the common cold?
Rhinovirus
What are the different types of coronaviruses?
Typically divide into alpha and beta coronaviruses. In the alpha coronaviruses, they cause haemachrome viruses 229E and NL63 which cause the common cold. The beta coronaviruses divide into:
- A - OC43 and HKU1 - cause common cold
- B - SARs-CoV1 and SARs-CoV2
C - MERS
What are post-influenza secondary manifestations?
Post-influenzas secondary bacterial lung infection with S. pneumonia, H. influenza and S. aureus
What is Respiratory Syncytial Virus?
Common respiratory virus that usually causes mild, cold-like symptoms. Most people recover in a week or two, but RSV can be serious, especially for infants and older adults. Aerosolization of respiratory secretions.
Bronchiolitis affects children under 2 years. This is inflammation of the bronchioles. This leads to cough, wheeze, hypoxia and apnoea.
How can HIV progress?
Initially, 2-6 weeks after transmission, patients may develop an acute seroconversion illness (flu-like).
- Asymptomatic chronic infection follows. This can be 5-15 years. A steady state between the production of new viruses, CD4 cells are dying, the body makes more and more viruses are made. The patient is asymptomatic. At some point the virus starts to take over and the steady state shifts, increasing the viral load and the CD4 count is low. They then become very immunodeficient.
- AIDS = rise in viral load and fall in CD4 count, patient becomes vulnerable to opportunistic infections. They are susceptible to developing AIDS defining illnesses: e.g. pneumocystis pneumonia, cryptococcal meningitis, Kaposi’s sarcoma.
Give an account Hepatitis A.
Endemic in the developing world, associated with contaminated water. Associated with lower socio-economic groups where people live in closer conditions, tourist returning from endemic areas and MSM.
Spread via faecal-oral transmission. Viruses shed in the faeces in large volumes of an infected individual.
It manifests as nausea, myalgia, fevers - progressing to jaundice and Right upper quadrant paint.
Which hepatitis virus have a high mortality rate (25%) in pregnant women?
Hepatitis E. In Western Europe and North America, it is seen in cluster cases associated with pigs/uncooked pork.
It is spread via faecal-oral transmission. Viruses shed in the faeces in large volumes of an infected individual.
It manifests as nausea, myalgia, fevers - progressing to jaundice and Right upper quadrant paint.
What virus can hepatitis D not survive without?
Hepatitis B. Hepatitis B is a blood borne virus spread vertically in LEDC; other methods include sexual, paraentral and needle stick.
After transmission, acute clinical hepatitis may occur - 90% of children and 50% of young adults are asymptomatic.
Hepatitis B is then cleared or persists and becomes chronic. Risk of chronicity is inversely related to age of infection. 90% perinatally acquired infection persists to chronic compared to only 5% in adult-acquired infections.
Overtime chronic hepatitis develops into cirrhosis which develops into hepatocellular carcinoma.
Give the methods of transmission of Hepatitis C.
Sharing needles, needle sick injuries and transfusion of contaminated products. Vertical and sexual transmission is less common.
How is norovirus transmitted?
Ingestion/inhalation of aerosolised vomit particles. Infection leads to and gastroenteritis, diarrhea and vomiting.
Vomiting is the dominate feature.
