Infections: Encephalitis; Glandular Fever; Mumps

Question 1

What is the most common viral cause of encephalitis in children [1] and neonates [1]

Name some other viral causes [5]

Answer 1

The most common viral cause is herpes simplex virus (HSV)
- In children the most common cause is herpes simple type 1 (HSV-1) from cold sores.
- In neonates it is herpes simplex type 2 (HSV-2) from genital herpes, contracted during birth.

Other causes:
* VZV w chickenpox
* CMV w immunodeficiency
* EBV w infectious mononucleosis
* Enterovirus, adenovirus and influenza virus

Question 2

Describe the presentation of encephalitis in children [4]

Answer 2

• Altered consciousness
• Altered cognition
• Unusual behaviour
• Acute onset of focal neurological symptoms
• Acute onset of focal seizures
• Fever

Question 3

Describe how the symptoms of meningitis differ from encephalitis [4 for each]

Answer 3

Meningitis:
- typically presents with headache
- fever
- neck stiffness (nuchal rigidity),
- photophobia
- and a positive Kernig’s or Brudzinski’s sign

Encephalitis:
- altered mental status
- seizures
- focal neurological signs such as hemiparesis or aphasia
- behavioural changes.

Question 4

How would you dx encephalitis? [+]

Answer 4

Lumbar puncture, sending cerebrospinal fluid for viral PCR testing:
- Lymphocytosis
- Elevated proteins
- PCR for HSV, VZV and enteroviruses

CT scan if a lumbar puncture is contraindicated
MRI scan after the lumbar puncture to visualise the brain in detail:
- medial temporal and inferior frontal changes
- normal in 1/3 patients

EEG recording can be helpful in mild or ambiguous symptoms but is not always routinely required:
- lateralised periodic discharges at 2 Hz

Swabs of other areas can help establish the causative organism, such as throat and vesicle swabs

HIV testing is recommended in all patients with encephalitis

Question 5

What are you specifically looking for on LP when assessing for encephalitis? [3]

Answer 5

Lumbar puncture, sending cerebrospinal fluid for viral PCR testing:
- Lymphocytosis
- Elevated proteins
- PCR for HSV, VZV and enteroviruses

Question 6

What would CI an LP? [3]

Answer 6

haemodynamically unstable, active seizures or post-ictal.

Question 7

How do you treat encephalitis? [3]

Answer 7

Aciclovir is usually started empirically in suspected encephalitis until results are available. Other viral causes have no effective treatment and management is supportive.

Intravenous antiviral medications are used to treat the suspected or confirmed underlying cause:
* Aciclovir treats herpes simplex virus (HSV) and varicella zoster virus (VZV)
* Ganciclovir treat cytomegalovirus (CMV)

Question 8

Complications of Encephalitis include [6]

Answer 8

Complications of Encephalitis:
* Lasting fatigue and prolonged recovery
* Change in personality or mood
* Changes to memory and cognition
* Learning disability
* Headaches
* Chronic pain
* Movement disorders
* Sensory disturbance
* Seizures
* Hormonal imbalance

Question 9

Infectious mononucleosis (aka glandular fever) is caused by which virus in 90% cases [1]

Answer 9

Infectious mononucleosis (glandular fever) is caused by the Epstein-Barr virus (EBV, also known as human herpesvirus 4, HHV-4) in 90% of cases. Less frequent causes include cytomegalovirus and HHV-6. It is most common in adolescents and young adults.

Question 10

What is the classic triad of symptoms of infectious mononucleosis? [3]

What are other features? [+]

Answer 10

The classic triad of sore throat, pyrexia and lymphadenopathy is seen in around 98% of patients:
* sore throat
* lymphadenopathy: may be present in the anterior and posterior triangles of the neck, in contrast to tonsillitis which typically only results in the upper anterior cervical chain being enlarged
* pyrexia

Other features:
* 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)
* a maculopapular, pruritic rash develops in around 99% of patients who take ampicillin/amoxicillin whilst they have infectious mononucleosis

Palatal petachie

TOM TIP: Look out for the exam question that describes an adolescent with a sore throat, who develops an itchy rash after taking amoxicillin. Mononucleosis causes an intensely itchy maculopapular rash in response to amoxicillin or cefalosporins.

Question 11

How do you dx glandular fever? [1]

Answer 11

NICE guidelines suggest FBC and Monospot in the 2nd week of the illness to confirm a diagnosis of glandular fever.

Question 12

Managment of glandular fever? [3]

Answer 12

• rest during the early stages, drink plenty of fluid, avoid alcohol
• simple analgesia for any aches or pains
• consensus guidance in the UK is to avoid playing contact sports for 4 weeks after having glandular fever to reduce the risk of splenic rupture

Question 13

In which cases would you test for specific antibodies to infectious mononucleosis? [1]

Which antibodies do you specifically test for? [1]

How do you specifically test for these antibodies? [2]

Answer 13

In certain diseases (such as HIV) we can test for specific antibodies to the disease:
- In infectious mononucleosis, the body produces something called heterophile antibodies, which are antibodies that are more multipurpose and not specific to the EBV antigens. It takes up to 6 weeks for these antibodies to be produced

We can test for these heterophile antibodies using two tests:
* Monospot test: this introduces the patient’s blood to red blood cells from horses. Heterophile antibodies (if present) will react to the horse red blood cells and give a positive result.
* Paul-Bunnell test: this is similar to the monospot test but uses red blood cells from sheep.

Question 14

It is possible to test for specific EBV antibodies. These antibodies target something called []

How would you interpret these antibodies? [2]

Answer 14

It is possible to test for specific EBV antibodies. These antibodies target something called viral capsid antigen (VCA):
* The IgM antibody rises early and suggests acute infection
* The IgG antibody persists after the condition and suggests immunity

Question 15

EBV infection is associated with certain cancers, notable []

Answer 15

EBV infection is associated with certain cancers, notable Burkitt’s lymphoma.

Question 16

Answer 16

Haemolytic anaemia
- haemolytic anaemia secondary to cold agglutins (IgM)

Question 17

Answer 17

Atypical lymphocytes
- lymphocytosis: presence of 50% lymphocytes with at least 10% atypical lymphocytes

Question 18

Answer 18

Infectious mononucleosis - deranged liver function tests

Question 19

Answer 19

Infectious mononucleosis - palatal petechiae

Question 20

Answer 20

Infectious mononucleosis - cold agglutins (IgM)

Question 21

Answer 21

Heterophile antibodies - infectious mononucleosis

Question 22

How is mumps spread? [1]

What is the incubation period? [1]

Answer 22

Mumps is a viral infection spread by respiratory droplets.

The incubation period is 14 – 25 days.

Mumps is usually a self limiting condition that lasts around 1 week. Management is supportive, and involves treating the complications if they occur.

Question 23

Describe the pathophysiology of mumps [+]

Answer 23

The mumps virus enters the body through respiratory droplets or direct contact with saliva from an infected individual. It then attaches to and penetrates epithelial cells in the upper respiratory tract via receptors such as sialic acid.

Following attachment, viral replication occurs within these host cells. The newly formed virions are released and disseminate through viremia to various tissues including salivary glands, pancreas, testes, ovaries, and central nervous system (CNS).

Invasion of the parotid gland leads to **inflammation and swelling - a hallmark feature of mumps. **This is due to viral cytopathic effects causing cell lysis and release of inflammatory mediators such as cytokines.

The pancreas may also be affected leading to transient hyperglycaemia or even acute pancreatitis. Involvement of gonadal tissue can result in orchitis in males or oophoritis in females.

CNS involvement may manifest as meningitis or encephalitis. Viral invasion of ependymal cells lining the ventricles or meninges incites an inflammatory response resulting in these neurological complications.

Question 24

Describe the presentation of mumps [5]

It can also present with symptoms of the complications, such as: [3]

Answer 24

Patients experience an initial period of flu-like symptoms known as the prodrome:
* Fever - 3/4 days, oscillates
* Muscle aches
* Lethargy
* Reduced appetite
* Headache
* Dry mouth

Parotid gland swelling, either unilateral or bilateral, with associated pain is the key feature that should make you consider mumps!
- May lead to ear lobe being elevated and jaw angle becoming obstructed
- Associated with tenderness, pain exacerbated by chewing, fever, malaise, anorexia, and headache.

It can also present with symptoms of the complications, such as:
* Abdominal pain (pancreatitis)
* Testicular pain and swelling (orchitis)
* Confusion, neck stiffness and headache (meningitis or encephalitis)

Question 25

Describe how you investigate mumps [1]

Answer 25

Serology:
- This is the initial investigation of choice for suspected mumps infection. The presence of IgM antibodies against the mumps virus in a patient’s serum indicates a recent or ongoing infection.
- A positive IgG test may suggest past exposure or vaccination but could also indicate an active infection if found in high titres.

The diagnosis can be confirmed using PCR testing on a saliva swab.

Mumps is a notifiable disease, meaning you need to notify public health of any suspected and confirmed cases

Question 26

How do you manage mumps? [1]

Answer 26

Management is supportive, with rest, fluids and analgesia. Mumps is a self limiting condition. Management of complications is also mostly supportive.

Question 27

Name 5 complications of mumps [5]

Answer 27

Complications
* Acute Pancreatitis
* Orchitis
* Meningitis
* Sensorineural hearing loss
* Glomerulonephritis

Question 28

When does the orchitis typically occur with regards to other features of mumps? [1]

Answer 28

Generally within a week post-parotitis.

Question 29

How do you differentiate mumps from bacterial parotitis? []

Answer 29

A distinguishing feature from mumps is that in bacterial parotitis, pus may be expressed from the Stensen’s duct during physical examination.

Question 30

Sialolithiasis involves the formation of stones (sialoliths) within the salivary glands or ducts. The most commonly affected gland is the submandibular gland followed by the parotid gland.

How do you distinguish this from mumps? [2]

Answer 30

Patients often present with recurrent episodes of painful swelling of the affected gland during meals. This is a key distinguishing feature from mumps, which does NOT typically exhibit mealtime exacerbations.

On examination, a palpable stone may be felt in the duct and imaging studies can confirm the diagnosis.

Question 31

If a patient is unvaccinated agaisnt mumps - how would you manage them if they’ve had a mumps exposure? [1]

Answer 31

Vaccination: Ensure up-to-date immunisation status with MMR (measles, mumps and rubella) vaccine as per UK guidelines. Post-exposure prophylaxis with MMR vaccine within 72 hours can be considered in unvaccinated individuals exposed to mumps.