It is possible that the Taura virus was introduced as carrier adults from their original site in Hawaii, developed in the hatchery and spread about via deliveries. Checks for Taura virus in the Hawaiian adult stock, however, were seen to be negative before the Texas mortality began. Also, the extra effort that researchers were using to keep up with the progress and promise of the new line of Pacific white shrimp continued to show the broodstock to be free of viruses. While seed shrimp of infected crops came ultimately from one hatchery near Harlingen, Texas, the shipments to facilities where the large losses became manifest occurred only after the virus disease expressed in the hatchery's adjacent ongrowing ponds. Earlier shipments to other facilities never became diseased from Taura virus.
Producers believe that contamination came from the outside.
One suggestion regarding possible introduction is the dispersal by other animals. Producers remark that gulls are particularly abundant at the time of shrimp mortalities and the same birds are seen to fly from ponds to coastal islands. May is the month that most many migratory bird species, including gulls, arrive along our coast after frequenting areas of infection as far south as Peru and Ecuador, areas known for recent massive losses from Taura virus. Gulls, however, do not take that migratory course when passing through Hawaii, another site where Taura virus has been detected in production systems. In study of the virus in South America, Dr. Jim Brock, Hawaii Aquatic Veterinarian, found the virus in the gut of aquatic insects, another potential carrier.