Advances in diagnosis and management of shrimp virus diseases in the Americas

The most important diseases of cultured penaeid shrimp, in terms of economic impact, in Asia, the Indo-Pacific, and the Americas, have infectious etiologies. Although diseases with bacterial, fungal, and parasitic etiologies are also important, certain virus-caused diseases stand out as the most significant. The pandemics due to the penaeid virus Taura Syndrome Virus, Yellow Head Virus, WSSV, TSV, YHV, and IHHNV [White Spot Syndrome Virus] have collectively cost the penaeid shrimps industry billions of dollars in lost crops, jobs, and export revenue. Although not as sudden nor as catastrophic in their onset and course, certain bacterial, fungal, and parasitic diseases of shrimp have also been responsible for very significant production losses, and the relative importance of many of these diseases should not be discounted. The social and economic impacts of the pandemics caused by WSSV and TSV have been especially profound in the Americas, and in the wake of these viral pandemics the shrimp culture industry has sought ways to restore the industry's levels of production to the pre-virus years. Central to improving disease prevention and management strategies in the incorporation of the concepts of biosecurity into shrimp farm design and operational strategies. Disease management in shrimp aquaculture is an important component to biosecurity of farms and to the sustainability of individual farms, shrimp farming countries, or entire geographic regions. The first step in disease management requires the availability of accurate and reliable diagnostic methods and knowledge of the biology of the diseases of concern. The recognition of the need for biosecurity and disease management in the Americas is reflected in the recent proliferation of shrimp disease diagnostic laboratories in the Americas. Where there were only a handful of shrimp disease diagnostic laboratories a decade ago, there are 40 or more such laboratories serving the industry today. Diagnostic methods maybe applied to determining the cause of disease that are adversely affecting the culture performance or survival of farmed shrimp stocks or they may be used for surveillance purposes to screen for the presence of specific pathogens in otherwise healthy shrimp for the purpose of disease control. As diagnostic methods have improved and become more widely available, the interest in culturing specific pathogen-free (SPF) shrimp stocks in biosecure facilities has increased markedly in many regions in the Americas. The methods being used in shrimp disease diagnostic laboratories in the Americas were recently surveyed . Of the 40 laboratories contacted, 27 responded to the survey. Approximately 75% of the labs responding to the survey provide diagnostic services using both molecular (PCR, RT-PCR and gene probes) and classical (routine histology and microbiology) methods, while nearly all (93%) of the diagnostic labs offer diagnostic testing and screening services based on molecular methods (i.e. assays with gene probes and PCR/RT-PCR).