Comparison of in vitro-cultured and wild-type Perkinsus marinus. III. Fecal elimination and its role in transmission

Diseases of Aquatic Organisms

Marnita M. Chintala¹  Susan E. Ford¹  David Bushek¹ 

关键词: Disease;    Parasite;    Oyster;    Crassostrea virginica;    Infection;    Modes of transmission;   

DOI  :  10.3354/dao051217

学科分类：生物科学（综合）

来源: Inter-Research

【 摘 要 】

ABSTRACT: Perkinsus marinus, a pathogen of the eastern oyster Crassostrea virginica, is transmitted directly among oysters. Previous studies found viable P. marinus parasites in the feces and pseudofeces of oysters within hours ofinjection with parasites, suggesting that the parasite may be voided from live oysters and subsequently dispersed in the water column. The experiments described here were designed to quantify P. marinus shed in the feces and pseudofeces ofexperimentally infected oysters. The results indicated that parasites were shed in 2 phases. A Œdecreasing¹ phase occurred within 2 wk of challenge and before net parasite proliferation began in the host. An Œincreasing¹ phase occurred after P.marinus had begun replicating. The quantity of P. marinus recovered in the feces and pseudofeces of exposed oysters was only about 5% of the dose administered. In vitro-cultured P. marinus were eliminated at a greater rate thanwild-type P. marinus and the fraction discharged was not associated with culture phase. Oysters that were continuously dosed with P. marinus in their food gradually lost the ability to discard the parasite in pseudofeces. The quantity ofP. marinus shed in feces of infected oysters was correlated with both the P. marinus body burden and subsequent survival time, suggesting that noninvasive fecal counts could predict infection intensity and survival. The results indicate thatin an epizootic, shedding of P. marinus via feces is relatively small compared to the potential number released by cadavers of heavily infected oysters, but that fecal discharge may be important in transmission before infections become lethal.

【 授权许可】

Unknown