Infectious Diseases exam scenario

Infectious Diseases

Test yourself with this case of a 35 year old male from Uganda, who has been admitted following a seizure in a local nightclub.

Seizure case

A 35 year old male from Uganda is admitted following a seizure in a local nightclub.

On admission.
Temp 382
O2 Sats 94% Air
GCS 14/15

On his calf he appears to have a 4cm pigmented purplish lesion.

His admission CT Brain shows multiple ring enhancing lesions.

What is the most likely cause of his seizure

  • Brain metastases
  • Toxoplasmiosis
  • None of thelisted answers
  • Cryptococci
  • Pneumocysitis Carinii


Ring enhancing lesions with contrast on the CT can be associated with cancer, but they’re commonly described in patients with a brain abscess. The patient is young, making cancer a less likely option.

The prevalence of HIV in Uganda is significantly higher than the UK, and as such for the purposes of an exam he has a strong risk factor for AIDS.

Toxoplasmosis classically causes there findings: ting enhancing lesions. Its treated with pryimethamina and sulphadiazine.

What would you expect his CD4 count to be?

  • <50×10 6/ml
  • <100×10 6/ml
  • <200×10 6/ml
  • <500×10 6/ml
  • <800×10 6/ml
  • You have no way of estimating on the CD4 count from the data presented

<200×10 6/ml

As toxoplasmosis is an AIDS defining illness, you would expect the CD4 count to be <200. This is the cut off lab test for distinguishing AIDS and HIV, although there are a number of AIDS defining illnesses that occur with a CD4 count of <200 and can therefore be used to define AIDS in the absence of a blood test.

What’s the most likely underlying diagnosis?

  • Toxoplasmosis
  • AIDS
  • HIV
  • Common Variable Immune deficiency
  • None of the Listed Diagnoses


He has an AIDS defining illness in that he seems to have developed toxoplasmosis.


He also has a rash on the inside of his mouth. It is purplish and well demarkated. What is the most likely aetiology of this?

  • Candida
  • Streptococci
  • Staphlococci
  • Mycobacterium
  • None of the Listed Diagnoses

None of the Listed Diagnoses

Its likely to be the AIDS defining tumor of Kaposi sarcoma.

These can occur anywhere in the GI tract of on the skin (e.g. oesophageal).

Other “Cancers” associated with the immunosupression effect of HIV include Lymphoma (esp. Burkittts).


He is also found to have widespread lymphadenopathy. A LN biopsy confirms the diagnosis of Burkitts Lympoma.
What is this specifically associated with?

  • Epstein Barr Virus Infection
  • Human Herpes Virus
  • Cryptococci
  • Microsporidia
  • Cytomegalovirus
  • Parvovirus

Epstein Barr Virus Infection

Burkitt’s Lymphoma is associated with EBV infection, and common in AIDS.