Florida's 2005 Cyclospora Outbreak: A Case Study of a Large, Diffuse Outbreak of an Emerging Pathogen Caused by an Emerging Vehicle

 

Speaker:                     Roberta M Hammond, AA, BA, MA, PhD

Food and Waterborne Disease Coord., Florida Department of Health

 

Level of Knowledge: Multi-Level

 

Short Abstract:

Typical vehicles of past Cyclosporiasis outbreaks include raspberries, basil, lettuce, snow peas and water.  Though water has been implicated, 90% of outbreaks of Cyclosporiasis are foodborne.  Cyclosporiasis is endemic in many developing countries and is often associated with diarrhea in travelers to Asia, the Caribbean, Mexico and Peru.   CDC reports that there have been 5,000 cases reported in the last 5 years.  The 2005 Florida outbreak was the single largest reported Cyclosporiasis outbreak in Florida history.  Illness is caused by Cyclospora cayetanensis, a single celled protozoan with symptoms of watery diarrhea, nausea, loss of appetite, abdominal pain, fatigue and weight loss.  The case fatality rate is very low.  The incubation period is 1-7 days, usually about 1 week and the ensuing illness can last anywhere from 1-3 weeks.

Long Abstract:

This foodborne outbreak was caused by Cyclospora cayetanensis, a single celled protozoan with symptoms of watery diarrhea, nausea, loss of appetite, abdominal pain, fatigue and weight loss.  The case fatality rate is very low.  The incubation period is 1-7 days, usually about 1 week and the ensuing illness can last anywhere from 1-3 weeks.  Typical vehicles include raspberries, basil, lettuce, snow peas and water.  Though water has been implicated, 90% of outbreaks of Cyclosporiasis are foodborne.  Cyclosporiasis is endemic in many developing countries and is often associated with diarrhea in travelers to Asia, the Caribbean, Mexico and Peru.   CDC reports that there have been 5,000 cases reported in the last 5 years.  Previous outbreaks in Florida include: 1996 (raspberries), 1997 (mesclun lettuce), 1999 (undetermined).  Other outbreaks in the US include: Chicago, 1990 (contaminated tap water), multi-state 1996 and 1997 (raspberries), N. Virginia/Baltimore/Washingtion, DC (fresh basil), and in other countries: Nepal, 1992 (untreated water).

In mid-April, 2005, a private laboratory reported a dozen cases of Cyclosporiasis to the Florida Department of Health.  The total number of cases reported in 2004 was 9, and the average for 2003-2005 for reporting week 14, ending April 16 (the week the positive results were received from the private lab) was 1.67, 20% higher than normally expected.  By reporting week 17, the percent increase was 162%, a clear indication of a possible outbreak.  Cases were reported from numerous counties and from visitors to Florida with no initial apparent pattern.  This began the investigation into the single largest reported cyclospora outbreak in Florida history.

This presentation will discuss the evolution of this outbreak and its investigation, the nature of the implicated food item and implications for further outbreaks and investigations thereof.

Learning Objectives:

  1. Outline the etiology of Cyclospora cayetanensis.
  2. Discuss the challenges in investigating a foodborne outbreak implicating a "stealth" ingredient.
  3. Name the typical food vehicles of cyclospora.