Chlamydophila psittaci in zoo parakeets: the risk for visitors

Abstract

This research was aimed at investigating the risk for visitors of zoos in relation to Chlamydophila psittaci. This is a gram negative obligate intracellular bacterium which can be transmitted from birds to humans. The research took place in a zoo in the Netherlands. To investigate the prevalence of C. psittaci in the population of birds, cloacaswabs were taken of 32 birds and a Clearview Chlamydia MF test and PCR were performed on these samples. To evaluate the compliance in hand washing observations of the visitors were done. One bird tested positive on a species specific Chlamydia PCR, but negative for Chlamydophila psittaci with real-time PCR. The prevalence of C. psittaci in this sample population of birds was low compared to the prevalence found in other studies in other bird populations. A maximum number of eight birds (8 %) could be diseased with this sample size. Exact infectious doses for humans are not known. Although the attack rates in reported outbreaks are not extremely high there is evidence that as little as a single contact might result in zoonotic transmission and consequent disease. The severity of the consequent disease can be high but a majority of people will only suffer from flu like symptoms. 346 visitors were observed, hand washing was performed by 18 (5,2 %) of them. The compliance in hand washing of visitors in this study was extremely low compared to other studies. In conclusion, with a maximal prevalence of eight percent, the risk of exposure for visitors is relatively small. But since severe symptoms upon infection might develop, preventive measurements to reduce the risk of transmission of the disease are absolutely necessary.