Viruses Flashcards
Cytomegalovirus (type, appearance, patterns):
- herpesvirus
- typically only disease causing in immunocompromised
- owl’s eye appearance (intranuclear inclusion bodies)
- congenital, mononucleosis, retinitis, encephalopathy, pneumonitis, colitis
Congenital CMV infection:
- growth retardation
- pinpoint petechial blueberry muffin skin lesions
- microcephaly
- sensorineural deafness
- encephalitis (seizures)
- hepatosplenomegaly
CMV mononucleosis:
- infectious mono like illness
- may develop in immunocompetent
CMV retinitis:
- common in HIV patients
- visual impairment e.g. blurred vision, fundoscopy: retinal haemorrhages and necrosis (pizza retina)
Dengue fever (transmission, incubation, features, management)
- viral haemorrhage fever
- transmitted by Aedes Aegypti mosquito
- incubation 7 days
- form of DIC - dengue shock syndrome
- headache, fever, myalgia, pleuritic pain, facial flushing, maculopapular rash, reduced platelet, increased ALT
- manage symptomatically, no antivirals
Ebola (virus type, locations, transmission, incubation)
- Filoviridae family
- West Africa - Guinea, Sierra Leone, Liberia
- human to human direct contact transmission
- incubation: 2-21 days
- not infectious until symptomatic
Features of ebola:
- sudden onset fever, fatigue, myalgia, headache, sore throat
- vomiting, diarrhoea, rash
- impaired liver and kidney
- internal and external bleeding
Malignancies associated with EBV:
- Burkitt’s lymphoma
- Hodgkin’s lymphoma
- nasopharyngeal carcinoma
- HIV - associated CNS lymphoma
Non-malignant association with EBV:
harry leukoplakia - indicative of HIV
Infectious mononucleosis causes and features:
- HHV4, CMV, HHV6
- triad: sore throat, lymphadenopathy, pyrexia
- malaise, anorexia, headache
- palatal petechiae
- splenomegaly (rare splenic rupture)
- hepatitis (transient increase ALT)
- lymphocytosis
- haemolytic anaemia secondary to cold agglutinins IgM
- maculopapular pruritic rash if ampicillin/amoxicillin whilst having mono
Diagnosis of infectious mononucleosis:
heterophil Ab test (monospot) - second week illness
What needs to be avoided with infectious mono?
contact sports 8 weeks after
Mumps virus type, spread, features, management:
- RNA paramyxovirus
- spread by droplets
- infective 7 days before and 9 days after parotid swelling starts
- incubation period: 14-21 days
- MMR vaccine
- fever, malaise, muscular pain, parotitis (unilateral initially becomes bilateral in 70%)
- manage with paracetamol, notifiable disease
Complications of mumps:
- orchitis - uncommon pre-pubertal males (4-5 days after start of parotitis)
- hearing loss - unilateral and transient
- meningoencephalitis
- pancreatitis
Norovirus (type, symptoms, transmission, diagnosis)
- most common cause gastroenteritis
- range of non encapsulated RNA virus species
- symptoms: 15-20 hours
- nausea, vomiting, diarrhoea, headaches, low grade fever, myalgia
- faeco-oral route
- virus enters cell via host receptor mediated endocytosis and replicates in small intestine
- diagnose with stool culture viral PCR
Parvovirus B19 - erythema infectiosum:
- fifth disease/slapped cheek syndrome
- mild fever
- noticeable rash after few days
- feels better after rash appears
- warm bath, sunlight, heat or fever can trigger recurrence of rash
- non infectious once rash appears
- adult - acute arthritis
- affects unborn baby in first 20 days
Other presentations of parvovirus B19:
- asymptomatic
- pancytopaenia in immunosuppressed patients
- aplastic crises e.g. in sickle cell (virus suppresses erythropoiesis for week)
Rabies
- causes acute encephalitis
- RNA rhabdovirus
- majority dog bites, also bat, raccoon and skunk
- travels up nerve axons towards CNS in retrograde way
- poor rural areas of Africa and Asia
Features of rabies:
- prodromal: headache, fever, agitation
- hydrophobia: water provoking muscle spasms
- hypersalivation
- negri bodies: cytoplasmic inclusion bodies found in infected neurons
Management of rabies:
- wash wound
- if already immunised - 2 further doses of vaccine
- if not, human rabies Ig along full vaccination course (administer around wound)
Rubella
- german measles
- togavirus
- congenital rubella syndrome risk
- 14-21 day incubation period
- infectious 7 days before and 4 days after rash onset
- prodrome e.g. low grade fever
- rash: maculopapular, initially face before spreading to whole body, usually fades by 3-5 days
- lymphadenopathy: sub occipital and postauricular
Complications of rubella:
- arthritis
- thrombocytopaenia
- encephalitis
- myocarditis
Yellow fever
- type of viral haemorrhage fever
- zoonotic infections e.g. Aedes mosquito
- incubation: 2-14 days
- mild flu-like illness lasting less than 1 week
- high fever, riggers, n&v, bradycardia
- brief remission followed by jaundice, haematemesis, oliguria
- if severe jaundice, haematemesis
- councilman bodies (inclusion bodies) - may be seen in hepatocytes
What are the live attenuated vaccines?
- BCG
- MMR
- Influenza (intranasal)
- oral rotavirus
- oral polio
- yellow fever
- oral typhoid
What are the inactivated vaccines?
- rabies
- hepatitis A
- influenza IM
What are the toxoid (inactivated toxin) vaccines?
- tetanus
- diphtheria
- pertussis
Conjugate vaccines:
- pneumococcus
- haemophilus
- meningococcus
HPV vaccine:
- gardasil
- 6,11,16,18
- 12-13 year old girls and boys (2 doses)
- also mwhswm <45yo against anal, throat and penile cancers
- injection site reactions common
Influenza vaccine in children:
- intranasal
- 1st at 2-3yo then anual
- live vaccine
- immunosuppressed - inactive, injection
- 2 doses if 2-9yo and never had vaccine
- more effective than injection
Contraindications to intranasal influenza vaccine:
- immunocompromised
- <2yo
- current febrile illness or blocked nose/rhinorrhoea
- current wheeze or history of severe asthma
- egg allergy
- pregnancy/breast feeding
- aspirin e.g. for Kawasaki’s due to Reye’s risk
ADR of intranasal influenza vaccine:
- blocked nose
- headache
- anorexia
How effective is the influenza vaccine:
75%
-10-14 days for Ab levels to be protective
When is the tetanus vaccine administered:
- 2mo, 3mo, 4mo, 3-5yrs, 13-18yrs
- 5 doses - long term protection
What do you give to someone who has a wound and had a full course of tetanus vaccines with the last dose <10 years?
nothing
What do you give to someone who has a wound and has had a full course of vaccines with the last dose >10 years?
- if tetanus prone wound: reinforcing dose of vaccine
- high risk wound: reinforcing dose + Ig
What do you give to someone who has a wound and an incomplete/unknown vaccine history?
- reinforcing dose of vaccine
- tetanus prone and high risk wounds: reinforcing dose of vaccine + Ig
