Diseases of complex aetiology affecting non-model species like pollinators, corals and bivalve molluscs remain difficult to decipher in natura as they are influenced by a high number of interwoven environmental and host factors. Recently, members of the consortium proposing the DECICOMP project have achieved a major breakthrough in the understanding of the major disease affecting Pacific Oysters (Pacific Oyster Mortality Syndrome, POMS), the main oyster species exploited worldwide. POMS is caused by a polymicrobial infection. Nevertheless, a series of additional factors (temperature, age, diet) are known to influence POMS. The objective of the DECICOMP project is to study how those additional parameters can influence the disease to i) decipher the whole complexity of POMS and ii) propose a modeling of epidemiological risks in oyster farms. This will help designing operational management strategies to mitigate POMS devasting effects on oyster farming.