Giant cell arteritis, polymyalgia rheumatica, and viral hypotheses: A multicenter, prospective case-control study

Objective. Although suspected, a viral etiology has never been proven in gi ant cell arteritis (GCA). We tested for viruses known to induce multinuclea ted giant cells in human pathology, which include the parainfluenza viruses (HPIV), respiratory syncytial virus, measles virus, herpesviruses type 1 a nd 2, and the Epstein-Barr virus. Methods, A multicenter case-control study on incident cases of temporal art eritis (TA) and polymyalgia rheumatica (PMR). Population based age and sex matched controls were randomly selected. Serological tests for IgG and IgM directed against the viruses listed above were performed, on blood samples taken at the time of clinical diagnosis. Results. Three hundred five new patients were included over a 5 year period , of whom 159 presented with positive biopsy TA, 70 with negative biopsy TA , and 76 with negative biopsy PMR. Thirty-eight percent of cases versus 20. 9% of controls were positive for IgM directed against HPIV (p = 0.00005). T he association was stronger in the positive TA subgroup [positivity rate 43 .31%; odds ratio with controls 2.89 (95% CI 1.82-4.60, p = 0.000006)] than in the PMR or negative biopsy TA subgroups. Only HPIV type 1 was associated with the disease, regardless of the season or the geographical origin of t he cases. Positivity rates for HPIV types 2 and 3 and for the other viruses tested were similar in cases and controls Conclusion. Our findings suggest that reinfection with HPIV type 1 is assoc iated with the onset of GCA in a subset of patients, particularly in cases with positive TA biopsy.