Infectious mononucleosis Flashcards
definition of infectious mononucleosis
Clinical syndrome caused by primary EBV infection. Also known as glandular fever.
lifelong latent infection
aetiology of infectious mononucleosis
Virus targets circulating B lymphocytes (lifelong latent infection) and squamous epithelial cells of oropharynx
EBV is gamma-herpes virus (dsDNA), present in pharyngeal secretions of infected individuals and is transmitted by close contact, e.g. kissing or sharing eating utensils.
EBV infection of the oropharyngeal epithelial cells leads to B cell infection with incorporation of the viral DNA into host DNA.
infected B cells disseminate and proliferate in lymphoid tissue throughout the body.
There is humoral (heterophile antibodies) and cellular (T cells-mediated) immune response and production of interleukin (IL)-2 and interferon-cytokines
The atypical lymphocytes, in the peripheral blood are primarily activated CD8+T cells.
Despite these immune responses, which control the initial lytic infection, EBV remains latent in lymphocytes. Reactivation may occur following stress or immunosuppression.
RF for infectious mononucleosis
kissing
sexual behaviour
epidemiology of infectious mononucleosis
common, 1 in 1000 incidence
2 age peaks: 1-6yrs (usually asymptomatic), and 14-20yrs; >90% of adult population are EBV IgG +ve
presenting symptoms of infectious mononucleosis
incubation period 4-6wks, may have abrupt onset
sore throat for >7days
fever
fatigue
headache
malaise
anorexia
sweating
abdo pain
resolution of symptoms usually within 2wks
signs of infectious mononucleosis
pyrexia
oedema and erythema of the pharynx, fauces and soft palate, with white/creamy exudate on the tonsils which becomes confluent within 1–2 days,
palatal petechiae.
Cervical/generalized lymphadenopathy,
splenomegaly (50–60%),
hepatomegaly (10–20%).
Jaundice (5–10%),
widespread maculopapular rash in patients who have received ampicillin.
tonsillar exudate
investigations for infectious mononucleosis
blood
- FBC (leukocytosis), LFT (high aminotransferases)
blood film
- lymphocytosis, >20% atypical lymphocytes (large irregular nuclei) - also present in CMV< HIV, parvovirus, dengue, toxoplasmosis, typhus, leukaemia, lymphoma, drug reactions, lead poisening
paul-Bunnel/monospot test
- detects presence of heterophile antibodies that are produced in response to EBV infection, but not against the virus ag
- (10–15%are heterophile Ab negative especially if<14 years)
- false +ve - pregnancy, autoimmune, lymphoma/leukaemia
throat swabs (culture and Ag testing) to exclude streptococcal tonsilitis
IgM or IgG to EBV viral capsid Ag
- present at onset of clinical illness
- Only needed in patients with compatible syndrome and negative Monospot test.
IgG against EBNA (Epstein–Barr nuclear antigen)
- 6-12wks after onset of symptoms
- presence of IgG EBNA, ,or the absence of IgG and IgM VCA, excludes acute primary EBV infection and should prompt consideration of CMV, HIV infection and toxoplasmosis.
reverse transcriptase viral PCR
management for infectious mononucleosis
Bed rest, paracetamol or NSAIDs for fever, throat discomfort and malaise.
Corticosteroids may be indicated for severe cases (e.g. haemolytic anaemia, severe tonsilar swelling, obstructive pharyngitis).
Advise against contact sports for 2 weeks, as increased risk of splenic rupture
complications of infectious mononucleosis
lethargy for months
resp - airway obstructio by oedematous pharynx, secondary bacterial throat infection, pneumonitis
haematological - haemolytic or aplastic anaemia, thrombocytopenia
GI/renal - splenic rupture from persistent splenomegaly, fulminant hepatitis, pancreatitis, mesenteric adenitis, renal failure
CNS - guillain-Barre syndrome, encephalitis, viral meningitis, brachial plexitis
EBV-associated malignancy - Burkitt’s lymphoma (sub-saharan Africa), nasopharyngeal carcinoma (china), post-transplant lymphoma, hodgkin’s lymphoma (usually mixed cellularity type)
Nearly 100% of patients with infectious mononucleosis develop a widespread maculopapular rash when given amoxicillin or ampicillin.
prognosis with infectious mononucleosis
Most make an uncomplicated recovery in 3–21 days. Immunodeficiency and death can occur very rarely
