Emergence of Salmonella serotype Enteritidis phage type 4 in Hawaii traced to locally-produced eggs.

OBJECTIVES

In August 1998, the Hawaii Department of Health observed a nine-fold increase in human Salmonella Enteritidis (SE) infections. Isolates were phage type 4 (PT4). An investigation was initiated to determine the source of the outbreak.

METHODS

A matched case-control study enrolled 38 cases. Cases were Hawaii residents with diarrhea and a stool culture yielding SE.

RESULTS

Eating eggs was associated with SE illness; 28 cases (74%) ate eggs in the three days before illness compared to 34 (45%) of 76 controls (MOR=3.0, 95% CI=1.4-7.4). Eighteen (47%) of 38 case patients ate eggs from Farm A compared to 11 (14%) of 76 controls (MOR=12.0, 95% CI=3.1-78.0); the eggs were not properly handled or refrigerated. Cultures from Farm A yielded SE. Human illness subsided following selective flock depopulation.

CONCLUSIONS

This outbreak highlights the importance of proper handling and refrigeration of eggs. The egg industry must implement quality assurance programs to prevent the spread of SE PT4 and human SE illness.