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GP beware - virology

Dr Eleni Nastouli, consultant in virology, discusses three cases of serious viral conditions mimicking less complex problems

Case 1

Mrs A, age 35, has just had a positive pregnancy test and visits her GP to discuss pregnancy. She also mentions that in the last few days she has been feeling generally unwell with non-specific symptoms and a mild upper respiratory tract infection. On examination she has a very fine maculopapular rash over her torso and extremities. The GP diagnoses mild viral illness. The patient remains well and is not seen again. The GP, however, sends booking bloods and the results are as follows:

  • HIV Ag/Ab – negative.
  • HBsAg – negative.
  • Syphilis EIA – negative.
  • Rubella IgG – positive.

The GP calls Mrs A with the results and reassures her. She has no further symptoms and has completely recovered, and is referred to the nearest maternity unit. She is abroad when due for the 20-week scan and re-arranges this for 28 weeks’ gestation. In this scan, severe asymmetric intrauterine growth restriction is diagnosed, and brain calcifications are noted. Amniotic fluid is tested for the presence of viruses and rubella RNA is detected by polymerase chain reaction. Retrospective testing of the booking sample reveals that rubella IgM and rubella IgG were detected – rubella IgG was of low avidity, indicating a recent infection. The woman had no history of MMR vaccination and was originally from a country where rubella is endemic. She had family visiting and one of the visitors had similar symptoms at the time.

GP’s diagnosis

Mild viral illness – rubella immune at booking.

Actual diagnosis

Rubella infection in the first trimester.

Clues

The history and documented examination of rash early in pregnancy. This should have been investigated properly at booking. Pathogens such as rubella, measles and parvovirus should be part of the differential diagnosis of maculopapular rashes in pregnancy, as well as HIV and syphilis. The latter should be tested regardless of booking blood results as women might acquire these infections in pregnancy.

Take-home message

Investigate all viral-type rashes in pregnancy. Take a careful history of vaccination and interpret the results with caution.

Case 2

Mr F is 23 and presents with a two-day history of aches and pains and an odd-looking rash all over his body. He just came back from Thailand, where he had a sore throat. He is on an antibiotic. The GP suggests the rash is probably an allergic reaction and recommends stopping the antibiotic. On examination the patient has a red throat with no exudate and a widespread palpable rash. He goes home and comes back a few days later with a fever, feeling worse, and with symptoms and signs of altered consciousness. The GP refers him to the local A&E where a lumbar puncture after a CT of the head is performed – 600 lymphocytes, mildly raised protein and lowered glucose were identified. A diagnostic serological test was performed and treatment was initiated.

GP’s diagnosis

Drug allergy.

Actual diagnosis

Primary HIV infection (PHI) with CNS involvement – a fourth-generation HIV antigen/antibody test was positive. At this stage, the laboratory was unable to type the infection as seroconversion-only antigen is detected and typing assays require presence of antibody. HIV-1 proviral DNA polymerase chain reaction was, however, positive – suggesting an HIV-1 infection. A repeat serological test a week later was requested as diagnosis of HIV infection requires two positive tests. Antibody was now present and typing confirmed HIV-1 infection.

Clues

The travel history, and a young man presenting with a rash and non-specific symptoms.

Take-home message

Take a sexual exposure history, as the above presentation can be compatible with HIV seroconversion or primary syphilis.

Case 3

Mrs K is 68 with a history of COPD. She is currently on prednisolone 40mg od for 14 days – this is the second course in the last three months. She presents with a history of feeling ‘under the weather’ and her husband reports some memory problems, claiming that she has not been ‘her usual self’ over the last couple of days. She has a normal neurological examination. The GP arranges a referral to a neurologist.

Unfortunately there is a delay in arranging the appointment in the neurology clinic and the patient deteriorates over the next couple of days. She presents at the local A&E with fever and altered consciousness. A lumbar puncture is performed after a head CT. There are a few lymphocytes in the cerebrospinal fluid, protein is raised and glucose is normal. There are 100 red cells, although this was not a traumatic tap. HSV1 is detected by polymerase chain reaction. Unfortunately, the patient develops permanent CNS sequelae following a stormy inpatient admission. 

GP’s diagnosis

Early dementia.

Actual diagnosis

HSV encephalitis.

Clues

Altered behaviour, memory loss and prescription of steroids.

Take-home message

Patients on high dose steroids or immunosuppression might have atypical presentations. The high mortality and significant morbidity of this condition requires urgent lumbar puncture and initiation of intravenous aciclovir at 10mg/kg tds. Fever is present in 90% of cases and should be part of the examination.

 

Dr Eleni Nastouli is the lead consultant in virology at University College London Hospital

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Readers' comments (10)

  • Very useful.

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  • Bit baffled about the rubella case (case 1).The lab should have posted a comment informing the GP that IgG serology cannot be relied upon to exclude a recent rubella infection and that further tests need to be done (such as IgM or testing for IgG avidity).Without this clarification the GP can be forgiven for assuming that a positive IgG serology is evidence of immunity.

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  • I agree with the comment about the rubella case- with IgG present most of us would read this as immunity present and not taken it further....

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  • The rubella case is very interesting and a huge learning point.I recently discussed this with our local consultant virologist and he clarified the following points which i'm sure the readers will find helpful:
    1.The purpose of the routine antenatal rubella IgG serology is to identify that group of women who will need rubella vaccincation post-natally.IT DOES NOT DIAGNOSE RECENT RUBELLA INFECTION and a positive serology does not exclude it.It merely tells you that if it's positive she doesn't need any rubella vaccination
    2.The routine antenatal rubella serology does not test for avidity (avidity helps to distinguish recent from old infection and needs to be specifically requested)
    3.If you wish to exclude a recent rubella infection then put on the request form "?recent rubella infection" and the lab will measure rubella IgM and avidity (which as already mentioned are not included in the routine antenatal rubella screen).

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  • excellent reminders-more like this, please

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  • This are great learning points and eye openers, please give us more

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  • Vinci Ho

    Is it a practical point that the lab should do both IgG and IgM automatically IF the GP entered for instance, 'Recent onset generalised body rash' in clinical details box?

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  • Vinci Ho

    Case 3 is probably about differentiating recent onset from insidious onset confusion , memory loss or delirium . One can argue that there were at least 10 more causes on top of HSV encephalitis which could present exactly the same way? I would always send the patient in as medical emergency if it was recent onset.

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  • WWWhattt? the lesson is that obviously the GP is always wrong or should have ordered the correct etc. etc. unless a virologist is on the end of the phone and we can discuss things - we do have this at the NNUH...so thanks but thanks

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  • EXCELLANT

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