Viruses Flashcards
What are the various presentations of Parvovarius B19?
Pancytopaenia
Aplastic crisis in sickle cell
Hydrops foetalis
How does hydrops foetalis occur?
Causes severe anaemia due to viral suppression of fetal erythropoiesis → heart failure secondary to severe anaemia → the accumulation of fluid in fetal serous cavities (e.g. ascites, pleural and pericardial effusions)
Treatment: Intrauterine blood transfusion
What type of virus is hepatitis B?
double-stranded DNA hepadnavirus
How is hepatitis B spread?
Blood
Bodily fluids
Vertical transmission to mother
What are the features of hepatitis B?
Fevers
Jaundice
Elevated liver transaminases
What are the complications of Hepatitis B?
Chronic hepatitis
Fulminant liver failure (1%)
hepatocellular carcinoma
Glomerulonephritis
Polyarteritis nodosa
Cryoglobulinaemia
What are the three antigens for Hep B? And their meaning
Surface antigen - HBsAB
Core antigen - HBcAg
DNA polymerase associated antigen HBeAg -
What does presence of HBsAG mean?
Early acute phase - actively infectious
What does presence of HBsAG and Anti-HBc mean?
Acute disease or chronic carrier
Antibody made against core antigen
What does presence of anti-HBs and anti-HBc mean?
Antibodies to surface and core
Suggests convalescing or immune to disease
May be immune from disease or vaccination
What does Anti-HBc mean?
Recent disease - taken after HBsAG disappeared and before anti-HBs made
Patient is considered infectious
What does an antibody level of Anti-HBs > 100 mean?
Adequate response
Booster only needed in 5 years
What does an antibody level of Anti-HBs 10-100?
Suboptimal response - one additional vaccine dose should be given. If immunocompetent no further testing is required
What does an antibody level of Anti-HBs <10?
Non-responder
Give further vaccine course (i.e. 3 doses again) with testing following.
How is hepatitis B treated?
Pegylated interferon-alpha (first one available) or other pegylated interferon
enofovir, entecavir and telbivudine (a synthetic thymidine nucleoside analogue)
What viruses causes Orf? How is it transmitted?
It is caused by the parapox virus.
Transmitted for sheep
What are features of off in humans?
Affects the hands and arms
Small, raised, red-blue papules
later may increase in size to 2-3 cm and become flat-topped and haemorrhagic
What does amantidine do? And its mechanism?
Anti-viral / Parkinsons disease
Inhibits uncoating (M2 protein) of virus in cell.
Also releases dopamine from nerve endings
What type of virus if hepatitis D?
Single stranded RNA virus
It is an incomplete RNA viruses and requires hepatitis B surface antigen for transmission cycle
What is a Hepatitis D “co-infection”?
Co-infection: Hepatitis B and Hepatitis D infection at the same time.
What is a Hepatitis D “superinfection”?
A hepatitis B surface antigen positive patient subsequently develops a hepatitis D infection.
How is Hepatitis D transmitted?
Fluids / Bodily fluid
What are the risks of a hepatitis D infection with hepatitis B?
fulminant hepatitis, chronic hepatitis status and cirrhosis.
What viruses cause genital warts?
HPV 6 and HPV 11
Management of genital warts?
First line: Podophyllum for multiple lesions and non-keronitonised
First line: Cryotherapy
Solitary keritonised lesions
Second line: Imiquimod
Which virus (and types) predispose to cervical cancer?
HPV 16, 18, 33
What type of virus is behind measles?
RNA paromyxovirus
What are the features of measles?
Prodromal phase
- irritable
- conjunctivitis
- fever
Koplik spots
- typically develop before the rash
- white spots (‘grain of salt’) on the buccal mucosa
Rash
- starts behind ears then to the whole body
- discrete maculopapular rash becoming blotchy & confluent
- desquamation that typically spares the palms and soles may occur after a week
Most common cause of death from measles?
Pneumonia
Most common complication post measles?
Otitis media
Complications post measles? (8)
Otitis media: the most common complication
Pneumonia: the most common cause of death
Encephalitis: typically occurs 1-2 weeks following the onset of the illness)
Subacute sclerosing panencephalitis: very rare, may present 5-10 years following the illness
Febrile convulsions
Keratoconjunctivitis, corneal ulceration
Increased incidence of appendicitis
Myocarditis
An unvaccinated child comes into contact with measles, how is this best managed?
Give MMR
Vaccinate antibodies develop faster than active infection
Should be given within 72 hours
What investigation should be done for measles?
IgM antibody test
What is the mechanism of action of acyclovir?
Guanosine analogue
require phosphorylated by tyrosine thymidine kinase to work
Leads to inhibition of DNA polymerase
What antiviral agent should be used in HSV and VZ?
Acyclovir
What antiviral agent should be used in CMV?
Ganicyclovir
What is the mechanism of action of ganicyclovir?
Guanosine analogue
requires phosphorylated by tyrosine thymidine kinase to work
Leads to inhibition of DNA polymerase
What is the complication of acyclovir?
Crystalline nephropathy
What is the complication of ganicyclovir?
Myelosuppression
What antiviral is used in chronic hep C and RSV?
Ribavirin
What is the mechanism of action of ribavirin?
Guanosine analogue
Inhibits IMP
Interferes with the capping of viral mRNA
What is the complication of ribavirin?
Haemolytic anaemia
What antiviral agent is used in Parkinson’s disease and influenza?
Amantadine
What is the mechanism of action of amandtadine?
Inhibits uncoating (M2 protein) of virus in cell.
Also releases dopamine from nerve endings
When is the antiviral agent foscarnet indicated? And its mechanism of action?
If HSV or CMV not responding to acyclovir
What are the complications of foscarnet?
Nephrotoxicity, hypocalcaemia, hypomagnasaemia, seizures
What is the indication for interferon alpha?
Chronic hepatitis B & C
Hairy cell leukaemia
What is the mechanism of action of interferon alpha?
Human glycoproteins which inhibit synthesis of mRNA
Side effects of interferon alpha?
Flu-like symptoms
Anorexia
Myelosuppression
What antiviral agent does not require phosphorylation to work?
Cidofovir
What is the indication for cidofovir?
CMV retinitis in HIV
What viruses can cause glandular fever?
EBV ( most common)
CMV
HHV-6
What is the classic triad of glandular fever?
Sore Throat
Cervical lymphadenopathy
*Anterior and posterior chain
Pyrexia
Please note: Tonsillitis typically give anterior china cervical lymphadenopathy - not posterior
What other features can be found in glandular fever?
Malaise, anorexia, headache
palatal petechiae
Splenomegaly - occurs in around 50% of patients and may rarely predispose to splenic rupture
hepatitis,
Transient rise in ALT
Lymphocytosis: presence of 50% lymphocytes with at least 10% atypical lymphocytes
Haemolytic anaemia secondary to cold agglutins (IgM)
Maculopapular, pruritic rash develops in around 99% of patients who take ampicillin/amoxicillin whilst they have infectious mononucleosis
What are the risk of varicella exposure to a pregnant mother?
Mother: Pneumonitis
Foetus:features of FVS include skin scarring, eye defects (microphthalmia), limb hypoplasia, microcephaly and learning disabilities
Management of VZV exposure in pregnancy?
If any doubt regarding immune status - IgG Varicella should be checked
If < 20 weeks gestation not immune antibody status - Give Immunoglobulin
If > 20 weeks no immun antibody status - Acyclovir to be given 7-14 days AFTER exposure
If rash present:
>20 weeks oral aciclovir should be given if the pregnant women is ≥ 20 weeks and she presents within 24 hours of onset of the rash
if the woman is < 20 weeks the aciclovir should be ‘considered with caution’
What malignancies are associated with EBV?
Burkitt’s lymphoma*
Hodgkin’s lymphoma
nasopharyngeal carcinoma
HIV-associated central nervous system lymphomas
What type of virus is EBV?
Herpesvirus
What is swine flu?
H1N1
It is a subtype of influenza A
What are the features of influenza?
fever greater than 38ºC
myalgia
lethargy
headache
rhinitis
sore throat
cough
diarrhoea and vomiting
What is the treatment for H1N1? Mechanism?
Oseltamivir (Tamiflu)
Oral medication
a neuraminidase inhibitor which prevents new viral particles from being released by infected cells
Zanamivir
inhaled medication*
also a neuraminidase inhibitor
What is the side effect of H1N1?
nausea, vomiting, diarrhoea and headaches
What is the side effect of oseltamivir? And zanamivir?
Oseltamivir: nausea, vomiting, diarrhoea and headaches
Zanamivir: may induce bronchospasm in asthmatics
How is measles spread?
Aerosol
What is 5’ths disease?
Rose-red rash makes the cheeks appear bright red, hence the name ‘slapped cheek syndrome’.
e virus can affect an unborn baby in the first 20 weeks of pregnancy
What test should be done in a pregnant mother with possible exposure to 5ths disease?
IgM
IgG
What is the most common and serious complication of chickenpox in adults? How is this treated?
Varicella pneumonia
Treated with IV acyclovir
What type of virus is hepatitis C?
RNA flavivirus
How is hepatitis transmitted?
Vertical transmission
(higher risk with HIV)
What are the features of heptatis C?
A transient rise in serum aminotransferases / jaundice
Fatigue
Arthralgia
What is the best investigation for hepatitis C?
HCV RNA
If a patient has an anti-HCV what does it mean?
Previous hepatitis C infection
What percentage of people get chronic hepatitis C?
what classifies as chronic hepatitis C?
majority (55-85%) will develop chronic hepatitis C
Persistence HCV RNA for > 6 months
Is there a vaccine for hepatitis C?
No
What are the complications of chronic hepatitis C?
Rheumatological problems:
- arthralgia, arthritis
- eye problems: Sjogren’s syndrome
- cirrhosis (5-20% of those with chronic disease)
Hepatocellular cancer
Cryoglobulinaemia: typically type II (mixed monoclonal and polyclonal)
Porphyria cutanea tarda (PCT)
Membranoproliferative glomerulonephritis
How is hepatitis C treated?
Aim of treatment is sustained virological response (SVR), defined as undetectable serum HCV RNA six months
Combination of protease inhibitors (e.g. daclatasvir + sofosbuvir or sofosbuvir + simeprevir) with or without ribavirin are used
What are the side effects of ribavirin?
Haemolytic anaemia
Cough
Women should not become pregnant within 6 months of stopping ribavirin as it is teratogenic
What are the side effects of interferon alpha?
flu-like symptoms, depression, fatigue, leukopenia, thrombocytopenia
What type of virus is hepatitis E? How is it spread?
RNA hepevirus
Faecal oral route
What are the features in hepatitis E?
Severe hepatitis in a pregnant woman - think hepatitis E
What are the features of Japanese encephalitis?
Headache, fever, seizures and confusion. Parkinsonian features indicate basal ganglia involvement. It can also present with acute flaccid paralysis
Basal ganglia inflammation
What is the diagnosis of Japanese encephalitis?
Diagnosis is by serology or PCR.
How is Lassa virus spread?
Excreta of infected African rats (Mastomys rodent) or by person-to-person spread.
How is the Marburg virus spread?
Risk factors for transmissions include caves/bats and primates.
How is hepatitis E spread?
Hepatitis E is associated with faecal-oral spread, commonly affecting shellfish and pork products.
What are the features of HSV 1 and HSV 2 infection?
primary infection: may present with a severe gingivostomatitis
cold sores
painful genital ulceration
How is gingivostomatitis managed? (HSV infection)?
oral aciclovir, chlorhexidine mouthwash
How should coldsores HSV be managed?
topical aciclovir although the evidence base for this is modest
How should you decide between dengue or chikungunya?
Absence of a rash makes chikungunya more likely than dengue.
Both have bone pain
