Viral Infections

AIDS

This is a condition caused by the human immunodeficiency virus (HIV).

The virus gains entry in CD4+ T cells. As the infection progresses, it leads to depletion of the CD4 cells, leading to a decrease in immune function.

This leads to acquired immunodeficiency syndrome (AIDS).

Transmission

Sexual Transmission

Vertical (mother to baby)

IVDU

Symptoms

Seroconversion (3–12 weeks following infection)

Flu-like symptoms with fatigue, fever, lymphadenopathy, sore throat, and arthralgia

Erythematous papular rash and mouth ulcers

Persistent generalised lymphadenopathy (swollen lymph nodes lasting > 3 months)

Chronic infection

This is usually asymptomatic until complications of immunosuppression develop

Key tests

There are a range of blood tests we can do to diagnose and monitor the disease.

Serology – this is a diagnostic test which assesses for antibody to HIV

Viral load – this provides quantification of HIV RNA. It is used to monitor response to antiretroviral therapy, rather than for diagnosis

CD4 count – this is usually not used for diagnosis, but instead used to monitor how the immune system is functioning and the rate of disease progression

Management

Highly active anti-retroviral therapy (HAART) – common therapy is to use 2 nucleoside reverse transcriptase inhibitors with a 3rd drug 

Infectious Mononucleosis (Glandular Fever)

This is a viral infection of the lymph nodes, usually seen in adolescents.

The virus is transmitted by saliva (hence known as the “kissing disease”) or sexual contact and infects the squamous epithelia cells of the oropharynx before spreading elsewhere in the body.

It can also affect the liver leading to inflammation.

It is most commonly due to the Epstein-Barr virus (EBV), but can also be due to other viruses (e.g., cytomegalovirus)

EBV increases risk of developing Burkitt’s and Hodgkin’s lymphoma.

Symptoms

Sore throat, fever, and large lymph nodes

Splenomegaly – increased risk of splenic rupture

Can cause hepatitis and potential jaundice

A pruritic rash in patients who take ampicillin/amoxicillin

Sore throat, fever and large lymph nodes

Key tests

FBC – increase in WCC (lymphocytosis); of these, over 50% are lymphocytes and at least 10% of these are atypical on blood film

Heterophile antibody test – tests for IgM antibodies to EBV viral antigen in the serum

A negative test suggests CMV could be a cause of the infectious mononucleosis

Management

Supportive with analgesia (paracetamol) as it usually self-resolves after 2–4 weeks

If inability to swallow, the patient may require admission to hospital for IV fluids and dexamethasone

Advise to avoid playing contact sports for 8 weeks due to risk of splenic rupture

Varicella Zoster Virus (VZV)

The varicella zoster virus is a herpesvirus that causes an initial infection but then stays dormant in the sensory ganglia.

It usually causes chickenpox in children but can then reactivate from dormancy causing other conditions later in life.

Chickenpox

This is a primary infection usually seen in children due to the varicella zoster virus.

It is spread via the airways and gives a rash usually 4 days post infection.

The most infectious period is 1–2 days before you get the rash and continues till all lesions are dry/crusted over.

Symptoms

Prodrome of high temperature

Pruritic vesicular rash on head and torso before spreading

Can lead to secondary bacterial infection of lesions

Complications:

Can lead to pneumonia, encephalitis

Disseminated haemorrhagic chickenpox, seen in immunocompromised patients

Management

Supportive treatment – antipyretics, applying calamine lotion for vesicles

If patient is aged > 14 and presents within 24 hours of rash onset, can give acyclovir (e.g., 800 mg 5 times a day for 7 days)

If immunocompromised, pregnant, or neonatal and exposed to chickenpox, discuss with a specialist as they may need varicella zoster Ig if varicella antibody negative

Ramsay Hunt syndrome (Herpes Zoster Oticus)

This is VZV reactivation from latency within CNVII, the facial nerve’s geniculate ganglion.

Shingles

This is a painful rash that occurs due to reactivation of VZV in the sensory ganglia.

A shingles vaccine is offered to patients when they turn 65 in the UK, those aged 70–79 and those over 50 with a weakened immune system.

There are 2 shingle vaccines in the UK: the live-attenuated vaccine (Zostavax) is avoided in immunocompromised patients and a newer non-live vaccine (Shingrix).

Risk factors

Old age

Immunocompromised

Having chickenpox at age < 18 months

Symptoms

Painful vesicular rash in dermatomal distribution

2–4 days before, pain or tingling in the area

Management

Oral acyclovir, rash usually heals within a month

However, patients can develop post-herpetic neuralgia which causes neuropathic pain in the dermatome affected by VZV

Herpes Zoster Opthalmicus

This refers to VZV reactivation from latency within the ophthalmic branch of the trigeminal nerve.

Classically, it is is proceeded by Hutchinson’s sign; the nasociliary branch of the ophthalmic nerve may be affected first causing a vesicular rash on the side of nose.

This can quickly lead to infection of the eyes, so must be managed quickly.

Symptoms

Vesicular rash occurring around or on the eyes with swelling of the eyelid

Eye pain, redness, and sensitivity to light

Fever and preceding rash which is tingling in nature

Can lead to chronic pain (post-herpetic neuralgia) and vision loss

Management

1st line oral acyclovir for 7–10 days, if severe may require IV antiviral

If eye involvement, refer to ophthalmology