SHORT REPORT Psittacosis outbreak after participation in a bird fair, Western France, December 2008 E. BELCHIOR 1,2 *, D. BARATAUD 1 , R. OLLIVIER 1 , I. CAPEK 3 , K. LAROUCAU 4 , B. DE BARBEYRAC 5 AND B. HUBERT 1 1 Cellule de l’InVS en re´gion (Cire) Pays de la Loire, Institut de Veille Sanitaire (InVS), Nantes, France 2 Programme de formation a ` l’e´pide´miologie de terrain (Profet), InVS, Saint-Maurice, France 3 Institut de Veille Sanitaire (InVS), Saint-Maurice, France 4 Agence franc ¸aise de se´curite´ sanitaire des aliments (AFSSA), Maisons-Alfort, France 5 Centre national de re´fe ´rence (CNR) des Chlamydiae, Bordeaux, France (Accepted 16 February 2011) SUMMARY In December 2008, three hospitalized cases of suspected psittacosis infection were notified by respiratory disease clinicians from a local hospital to the Regional Epidemiology Unit of Pays de la Loire, France. They all had attended a bird fair. A retrospective cohort study was conducted among exhibitors and organizers to identify potential risk factors in relation to this fair. Environmental and veterinary investigations were implemented to trace potential sources of infection. We identified two confirmed, two probable and 44 possible cases among participants. The attack rate in exhibitors and organizers was 38% (33/86). The median incubation period was 11 days (range 6–22 days). Individuals located in two particular sectors of the showroom were found to be at double the risk of developing psittacosis (relative rate 2 . 1, 95% confidence interval 1 . 03–4 . 18) than those in other sectors. Pooled faecal samples of birds belonging to a possible case exhibitor tested positive for Chlamydiaceae by PCR. Ventilation conditions in the showroom were inadequate. This investigation allowed the formulation of recommendations to prevent psittacosis in bird exhibitions which are held weekly in France. Key words : Investigation, outbreaks, psittacosis, zoonoses. Psittacosis is a bacterial zoonosis caused by Chla- mydophila psittaci. The reservoir is formed by all birds. They are often asymptomatic and may excrete the bacteria intermittently. Infection usually occurs when a person inhales aerosolized particles from birds’ dried faeces contaminated by the organism. Human-to-human spread has not been reported. Waste material in the birdcage may remain infectious for weeks. Psittacosis causes influenza-like symptoms, associated or not with pneumopathy with variable sev- erity. The incubation period ranges from 5 to 30 days. Treatment with specific intracellular antibiotics such as macrolides, cyclins and quinolones is effective when administered early. Most diagnoses are estab- lished by use of microimmunofluorescence (MIF) to test for antibodies against C. psittaci in paired sera. The direct detection of this microorganism is difficult because cell culture from the patient’s sputum, pleural fluid, or throat swab requires a high-protection lab- oratory and no commercially nucleic acid amplifi- cation test (NAAT) is available [1]. * Author for correspondence: Dr E. Belchior, De´ partement des maladies infectieuses, Institut de veille sanitaire, 12 rue du Val d’Osne, 94415 Saint-Maurice Cedex, France. (Email : e.belchior@invs.sante.fr) Epidemiol. Infect., Page 1 of 5. f Cambridge University Press 2011 doi:10.1017/S0950268811000409