Shigella dysenteriae type 1 infections in US travellers to Mexico, 1988.

In 1988, the number of Shigella dysenteriae type 1 (Sd1) infections reported in the USA increased five-fold over the annual mean from the previous decade. 44 (94%) of 47 interviewed patients reported recent travel to Mexico; 33 (75%) of these had been tourists to the Yucatan peninsula. 27 patients who had travelled to Mexico were admitted to hospital, of whom 2 had a haemolytic uraemic syndrome; none died. The antimicrobial resistance pattern and plasmid profile of the Yucatan strain were similar to those of the 1969-72 pandemic strain. Antimicrobial resistances and plasmid profiles were different in sporadic Western hemisphere strains. This is the first outbreak of Sd1 among US tourists and it is the largest known outbreak in the Western hemisphere since the early 1970s. The dominant Sd1 strain is similar to that which caused the catastrophic 1969-72 pandemic. Surveillance and control measures have been instituted in the Yucatan peninsula.