Infectious disease Flashcards
Give examples of an inactivated vaccine
- polio
- influenza
- hep A
- rabies
Give examples of a subunit and conjugate vaccine
- pneumococcus
- meningococcus
- haemophilus influenza type B
- hepatitis B
- pertussis
Give examples of live attenuated vaccines
- MMR
- BCG
- rotavirus
- nasal influenza
- chicken pox
Why is it important to give the HPV vaccine early?
Before become sexually active - to prevent them contracting and spreading HPV once they do.
What HPV strains does Gardasil protect against?
6,11,16 and 18
Which HPV strains cause genital warts?
6 and 11
Which HPV strains cause cervical cancer?
16 and 18
Who is offered the TB vaccine?
- babies at high risk
- e.g. with relatives from countries with a high prevalance
- live in urban areas with high rate of TB
- people in close contact with others with TB
- healthcare workers
What is meningitis?
Inflammation of the meninges (the lining of the brain and spinal cord). Normally due to viral or bacterial infection
What is meningococcal septicaemia?
Meningococcus bacterial infection in the blood stream causing the ‘non blancing rash’.
What is the pathophysiology behind the non blanching rash in meningococcal septicaemia?
DIC - disseminated intravascular coagulopathy and subcutaneous haemorrhages due to sepsis.
What bacteria causes meningococcal septicaemia?
Neisseria meningitis
What gram stain is neisseria meningitis?
Gram negative diplococcus
What bacteria commonly cause meningitis?
- neisseria meningitidis
- streptococcus pneumoniae
In neonates
- group B streptococcus
How does meningitis present?
- fever
- stiff neck
- photophobia
- vomiting
- headache
- altered conciousness
- seizures
- non blanching rash in meningococcal septicaemia.
How may meningitis present in neonates?
- fever or hypothermia
- vomiting
altered consciousness - hypotonia
- poor feeding
- buldging fontanelle
What investigations are done for suspected meningitis?
- CT scan if decreased consciousness / brain pathology suspected
- lumbar puncture
- blood culture
What tests can be performed to look for meningeal irritation?
- Kernig’s test
- Brudzinski’s test
How is Kernig’s test performed?
- lying the patient on back
- flex one hip and knee to 90degrees
- slowly straighten knee whilst keeping hip flexed
- in meningitis = spinal pain or resistance to movement
How is Brudzinski’s test performed?
- lying patient on back
- lift their head and neck gently to flex their chin to chest
- positive if causes involuntary flexion of the hips and knees
How is bacterial meningitis managed initially in the community?
If suspected meningitis AND non-blanching rash - give IM (or IV) dose of benzylpenicillin
- transfer immediately to hospital
How is bacterial meningitis managed (>3months old)?
- ideally do blood cultures and lumbar puncture before starting abx.
- above 3 months give ceftriaxone. Initally also give aciclovir to cover viruses. can also add vancomycin.
-steroids - dexamethasone - 4x daily for 4 days - to reduce frequency and severity of hearing loss and neurological damage - notify public health
How is bacterial meningitis managed (<3months old)?
- ideally do blood cultures and lumbar puncture before starting abx.
- give cefotaxamine plus amoxicillin ( cover listeria) Can also add vancomycin.
- steroids - dexamethasone - 4x daily for 4 days - to reduce frequency and severity of hearing loss and neurological damage
- notify public health
What post exposure prophylaxis can be given for bacterial meningitis?
Single dose of ciprofloxacin
What organisms commonly cause viral meningitis?
- herpes simplex virus
- enterovirus
- varicella zoster virus
What is given to treat viral meningitis?
Aciclovir.
Describe normal lumbar puncture results
- clear
- low protein
- 0.6-0.8 glucose
- low WCC (<5)
- negative culture
Describe bacterial lumbar puncture results
- cloudy
- high protein (released by the bacteria)
- low glucose (used up by bacteria)
- high WCC and neutrophils
- bacteria on culture
Describe viral lumbar puncture results
- clear
- mildly raised or normal protein
- normal glucose
- high WCC and lymphocytes
- negative culture
- positive viral PCR
What are some of the complications of meningitis?
- hearing loss
- seizures and epilepsy
- cognitive impairment and learning disability
- memory loss
- cerebral palsy
What is encephalitis?
Inflammation of the brain - this can be infective or autoimmune
What are the most common causes of encephalitis?
Viruses
- herpes simplex virus
- varicella zoster virus
- epstein-barr virus
+ many others
How does encephalitis present?
- altered consciousness
- altered cognition
- unusual behaviour (delerium)
- acute onset of focal neurological symptoms
- acute onset of seizures
- fever
How is encephalitis diagnosed?
- lumbar puncture - with viral PCR
- CT scan ( before lumbar puncture if indicated)
- MRI scan
- EEG can be helpful in mild symptoms
- HIV testing is recommended
How is encephalitis managed?
IV antivirals - aciclovir for HSV and VZV.
Ganciclovir for cytomegalovirus.
Repeat lumbar puncture may be done to ensure success.
What are some of the complications of encephalitis?
- lasting fatigue + prolonged recovery
- change in personality or mood
- changes to memory and cognition
- learning disability
- headaches
- chronic pain
- movement disorders
- seizures / epilepsy
What virus causes glandular fever?
Epstein Barr virus
How is glandular fever spread?
Through saliva - kissing, sharing cups, toothbruses etc.
What are the features of glandular fever?
- fever
- sore throat
- fatigue
- lymphadenopathy
- enlarged tonsils
- splenomegaly (rare = rupture)
Mainly in teenagers / young adults
What can happen if antibiotics are given for glandular fever?
Itchy maculopapular rash in response to amoxicillin or cephalosporins.
Do i need to know about tests and heterophile antibody testing for glandular fever>????
???
How is glandular fever managed?
- supportive management
- avoid spreading
- avoid alcohol (as impacts livers processing of alcohol)
- avoid contact sports (risk of splenic rupture)
What are some of the complications of glandular fever?
- chronic fatigue
- splenic rupture
- glomerulonephritis
- haemolytic anaemia
- thrombocytopenia.
Can also be associated with certain cancers –> Burkitt’s lymphoma
What is mumps?
A viral infection spread by respiratory droplets.
Why is mumps rare?
As vaccination offers around 80% immunity
What is the incubation period for mumps?
14-25 days
How does mumps present?
Initial flu like symptoms - known as the prodrome
- fever, muscle aches, headache, lethargy, reduced appetite
Then
- parotid gland swelling with associated pain (can be uni or bilateral)
Can also have symptoms of complications.
What are some of the complications of mumps?
- pancreatitis
- meningitis / encephalitis
- orchitis
- sensorineural hearing loss
How is mumps managed?
- supportive management - rest, fluids, analgesia
- notify public health
How is mumps diagnosis confirmed?
- PCR test of a saliva swab
- blood test for antibodies to the virus
What is HIV?
Infection with human immunodeficiency virus.
Describe the progression / pathophysiology behind HIV?
HIV is an RNA retrovirus. Enters and destroys CD4 T helper cells.
- initial flu like illness within first few weeks of infection
- then asymptomatic until it progresses enough to cause immunocomprimisation. This can then lead to AIDS.
How is HIV transmission prevented during birth?
Mode of delivery depends on mothers viral load
- If viral load <50copies/ml can have a normal vaginal delivery
- if >50 consider C section
- Give IV zidovudine during C section if the viral load is unknown or >10000.
Prophylaxis treatment may be given to the baby
- low risk = viral load <50 = given zidovudine for 4 weeks
- high risk = viral load > 50 = given zidovudine, lamivudine and nevirapine for 4 weeks (just remember 3 different antiretroviral meds)
Can a mother with HIV breastfeed?
It is never recommended to breast feed with HIV, even if the viral load is undetectable.
How is a child tested for HIV?
- HIV antibody screen - however can give positives in babies of HIV mums (<18mnths) as they cross the placenta. It can also take up to 3 months for antibodies to develop after exposure to the virus.
- HIV viral load - tests directly for viruses in the blood. Never falsely positive.
When would a child be tested for HIV?
- babies to HIV positive parents
- if immunodeficiency is suspected - getting unusual, severe or frequent infections
- young people who are sexually active can be offered testing if concerned.
- young people with risk factors - e.g. IV drug use, sexual abuse
When is testing for HIV done for children to HIV positive parents?
- HIV viral load - at 3 months old.
- HIV antibody test - at 24 months.
What is the treatment for HIV in children?
- specialist care - follow ups, psychosocial support etc.
- Antiretroviral therapy (ART)
- normal vaccinations (unless severely immunosuppressed)
- prophylactic co-trimoxazole if low CD4 count to protect against PCP infection (pneumocystis jirovecii pneumonia)
- treatment of any infections
What type of virus is Hepatitis B?
DNA virus.
How is hepatitis B transmitted?
direct contact with blood or bodily fluids
- vertical transmission during pregnancy and delivery
- sharing household products such as toothbrushes
- unprotected sex
- sharing needles
How does hepatitis B affect children?
Most fully recover within 2 months however some go on to become chronic hep B carriers.
The risk of chronic hep B after exposure is
- 90% for neonates
- 30% for under 5s
- under 10% for adolescents
This is mainly asymptomatic, however there is an increased risk of liver cirrhosis and hepatocellular carcinoma.
Which children are tested for hepatitis B?
- children of hepatitis B positive mothers (screen at 12 months or later)
- migrants from endemic areas
- close contacts of patients with active hep B
What are the 5 serological viral markers used for Hep B and what do they indicate?
- HBsAg - surface antigen - active infection
- HBeAg - E antigen - marker of viral replication and implies high infectivity
- HBcAb - core antibodies - active (IgG) or current (IgM - low = chronic, high = acute)
- HBsAb - surface antibody - indicates vaccination or past or current infection
- HBV DNA - a direct count of the viral load
Is it safe for a Hep B+ mother to breastfeed?
If the baby is properly vaccinated - hep B vaccine and immunoglobulin infusion, then it is safe to breastfeed.
How are children with chronic hep B managed?
Most are asymptomatic and don’t require treatment.
Regular specialist monitoring of
- serum ALT
- HbEAg
- HBV DNA
- physical examination
- liver ultrasound
If evidence of cirrhosis or hepatitis, will be treated appropriately.
What type of virus is Hep C?
RNA virus
Is it safe for Hep C+ mothers to breastfeed?
Yes. If nipples become cracked or bleed, temporarily stop whilst they heal.
How is Hep C managed in children?
Test babies of infected mothers at 18 months.
- children often clear the virus themselves
- medical treatment can be considered in children over 3 - pegylated interferon and ribavirin (less effected and less well tolerated than adult treatments)
- if chronic infection which isn’t causing any issues - treatment is typically delayed until adulthood as the available treatments are more effective
