By logistic regression we investigated associations between F. necrophorum-positivity and pre-specified criteria: age 13–30 years, symptom duration ≤ 3 days, absence of viral symptoms (e.g. cough, coryza), fever, tonsillar swelling/exudate, lymphadenopathy and CRP ≥ 50 mg/L. The gene discussed is CRP; the disease is Lymphadenopathy.