SUMMARY The incidence of antecedent events and serological evidence of preceding infection were studied in 100 patients with acute idiopathic neuropathy and age and sex matched control subjects in South-East England. Symptoms of respiratory infections occurred within one month before onset of neuropathic symptoms in 38% of patients and 12% of controls (p < 0 001) and symptoms of gastrointestinal infections in 17% of patients and 3% of controls (p < 0-005). Immunisations, insect bites and animal contact were equally common in the patient and control subjects. Eight per cent of patients had undergone an operation within the preceding 3 months. Six per cent of patients had co-existing "autoimmune" diseases. Serological evidence of recent infection was identified in 31% of patients. Campylobacter jejuni (14%) and cytomegalovirus (11%) were both significantly more frequently demonstrated in patients than controls. Serological evidence of recent infection with mycoplasma (1%), Epstein Barr virus (1-2%) and parvovirus B19 (4%) was also identified in the patients but not more frequently than in the controls. Possible explanations for the association of these agents with acute idiopathic neuropathy include possession of antigens shared with myelin and inhibition of suppressor mechanisms.At least half of the reported cases of Guillain-Barre syndrome (GBS) have been preceded by infections or other antecedent events during the few weeks before the neuropathy.' A large number of events have been incriminated and in one study of 1100 case records there were 735 possible associations.2 These include a variety of different infections, vaccinations, metabolic and neoplastic conditions. The only two case controlled studies suggested a higher incidence of respiratory infections3 and gastroenteritis4 among GBS patients than in appropriate controls. Serological tests have implicated cytomegalovirus (CMV) and Epstein Barr virus (EBV) more frequently than other viruses.

The inhibitory effects of urine samples taken from neonates and older children, some of which were known to be infected with cytomegalovirus, on the polymerase chain reaction (PCR) were investigated. Urea was the major inhibitory component of urine and inhibited the PCR at a concentration of more than 50 mM. Urine samples from older children were more inhibitory than those from neonates. This correlated with the higher concentration of urea generally found in urine samples from older children compared with neonatal urines. Two of 13 neonatal urine samples, however, were inhibitory despite low urea concentrations-presumably due to metabolites derived from parenteral nutrition. The inhibitory effects of urine were effectively removed by simple dialysis or ultrafiltration. The sensitivity and specificity of PCR for detecting cytomegalovirus DNA in urine were further improved by using "nested" primers and a modified PCR protocol entailing the use of reduced reactants in the first 20 cycles of a twostage 50 cycle PCR.

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Glandular fever is a significant risk factor for both acute and chronic fatigue syndromes. Transient new major depressive disorders occur close to onset, but are not related to any particular infection if they last more than a month.

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