Toxoplasma gondii Prevalence, United States

656 Emerging Infectious Diseases • www.cdc.gov/eid • Vol. 13, No. 4, April 2007 because bacteria could have been transported to Chile by ballast water from the Northern Hemisphere (1,4,6). As in previous outbreaks, shellfish responsible for this epidemic were harvested near international shipping lanes (1,3,4,6). The appearance of V. parahaemolyticus O3:K6 in Chile has thus converted the expansion of this strain into a real pandemic because this vibrio is now present in 5 continents. The persistence of V. parahaemolyticus in Region X might also have been encouraged by an expansion of finfish and shellfish aquaculture in that area. As in other parts of the world, expansion of these food industries could provide physical and nutritional substrates for vibrios to persist and propagate when growth is triggered by increases in temperature of seawater (1,2,8). Emergence of V. parahaemolyticus in Region X has also coincided with expansion of harmful algal blooms in the same area. These blooms are triggered by increases in seawater temperature and degradation of the coastal environment (9,10). A connection has been established between algal blooms and the presence of V. cholerae and cholera epidemics in the Gulf of Bengal and off the coast of Peru at the start of the Latin America epidemic (10). Further research is necessary to ascertain whether persistence of V. parahaemolyticus and epidemics are related to algal blooms in this region of Chile.