Reintroduction of clinically healthy tortoises: the herpesvirus Trojan horse.

Reintroduction programs of tortoises are often implemented for the recovering of natural populations. Introduced animals should be free of known diseases and pathogens, such as herpesviruses; these are well known to cause latent infections that may be reactivated under certain conditions. Thus, clinically healthy chelonians may carry and shed herpesviruses, posing a threat to naïve populations. From August 2006 to August 2007, blood and oral swabs were collected from 92 clinically healthy tortoises (Testudinidae), and a serum-neutralization test was performed to detect antibodies against tortoise herpesviruses. Oral samples were tested by polymerase chain reaction (PCR) for the presence of the tortoise herpesvirus. Anti-herpesvirus antibodies were detected in 9% of the tested animals, whereas 16% of the oral samples were positive for tortoise herpesvirus using PCR. The relatively high percentage of clinically healthy tortoises shedding herpesviruses suggests that, before reintroduction of tortoises, herpesvirus testing should be mandatory and that both serology and PCR should be applied.