Doctor of Philosophy (PhD)


Pathobiological Sciences

Document Type



White spot syndrome virus (WSSV) is the leading cause of morbidity and mortality in cultured penaeid shrimp worldwide, with infection resulting in up to 100% mortality in as few as 3-10 days. WSSV is capable of infecting over 90 species of aquatic crustaceans, including crabs, crayfish, and lobsters. Over the last two decades, WSSV emerged as a growing concern in farmed and wild-caught Louisiana crayfish. Louisiana is responsible for over 90% of crayfish production in the United States, contributing over $300 million to the state economy annually. First identified in Louisiana in 2007, WSSV is responsible for recurrent annual outbreaks of disease resulting in significant impacts on crayfish production and the local and state economies. The red swamp crayfish (Procambarus clarkii) is the predominant species grown and harvested in Louisiana. WSSV infection in red swamp crayfish presents similarly to WSSV in shrimp, causing rapid mortality with few clinical signs. Despite its prevalence, there is a dearth of information regarding WSSV in Louisiana red swamp crayfish. An experimental infection model published in 2016 determined the median lethal dose of a Louisiana WSSV isolate in red swamp crayfish, and few pilot studies examined the effects of water temperature and crayfish size and genetics on WSSV susceptibility and infection in crayfish. This research project aims to expand on previous research and investigate the genotypic and phenotypic diversity of Louisiana WSSV isolates in red swamp crayfish. The overarching hypothesis states that Louisiana WSSV isolates likely descended from ancestral Asian shrimp strains and developed genotypic and phenotypic diversity that contribute to significant disease outbreaks in the local crayfish ecosystem. To test this hypothesis, I 1) investigated the ancestral links and genotypic characteristics of five pathogenic strains of WSSV isolated directly from local Louisiana red swamp crayfish, 2) expanded on the previous model of experimental inoculation to examine phenotypic diversity in Louisiana WSSV isolates, and 3) developed a transmission model using my experimental data to investigate the potential operational effects of Louisiana WSSV phenotypes during outbreaks in Louisiana red swamp crayfish. These studies aim to further our understanding of the transmission dynamics of WSSV specific to Louisiana crayfish, which may help direct local disease surveillance and farm management practices.



Committee Chair

Hawke, John P.

Available for download on Friday, April 23, 2027