By Marcelle Dibrell
A Cryptosporidium outbreak originating in Puerto Rico has led to the infection of swimmers in Massachusetts and Rhode Island, prompting health officials with the Centers for Disease Control and Prevention to issue a warning about the fecal parasite, which can live for days in chlorinated swimming pools and spas.
The warning was prompted by a Cryptosporidium outbreak that took place earlier this year among the members of a Massachusetts college swim team.
Following a weeklong training trip to Puerto Rico, 19 members (out of 50) of both the men’s and women’s swim teams began experiencing diarrhea. On the 5th and 6th day after returning from Puerto Rico, symptomatic Massachusetts swimmers competed in two meets against New York and Rhode Island collegiate teams, raising concerns about the possibility of secondary transmission.
On the 9th day after returning from Puerto Rico, the college notified the Massachusetts Department of Public Health (MDPH), which encouraged the team members to submit stool
According to the 2023 Model Acquatic Health Code, Section 6.5.3, to disinfect pool water containing Cryptosporidiosis, technicians should lower the cyanuric acid to at least 15 ppm, increase chlorine levels to 20 ppm, and maintain pH at 7.5 for 28 hours. Visit https://www.cdc.gov/mahc/pdf/2023-MAHC-508.pdf. Photo credit CDC.
Cryptosporidium is a microscopic parasite that causes the diarrheal disease cryptosporidiosis. Both the parasite and the disease are commonly known as “Crypto.” samples to the Massachusetts State Public Health Laboratory for testing.
On the same day, MDPH notified the Puerto Rico, New York, and Rhode Island health departments. New York and Rhode Island health departments worked with their respective swim teams to identify secondary cases. At the same time, the Massachusetts college closed its swimming pool and hired a vendor to hyperchlorinate the pool water to inactivate Cryptosporidium. Symptomatic swimmers were excluded from the pool until 2 weeks after resolution of diarrhea.
Among the Massachusetts team members who received testing, 13 showed positive results for Cryptosporidium. Their symptoms began 3 to 7 days upon returning to Massachusetts. Exposure to water sources while in Puerto Rico included a waterfall, the ocean, and a training pool.
Among the New York and Rhode Island team members who competed with the infected Massachusetts team, two swimmers from the Rhode Island team became sick 7 days after that competition. They both tested positive for Cryptosporidium.
According to the CDC, the outbreak reveals three key findings: 1. The potential exists for secondary Cryptosporidium transmission among competitive swimmers.
2. Prompt testing of stool specimens from patients is necessary because further transmission could have occurred if the laboratory diagnosis of Cryptosporidium not prompted pool closures and cleaning.
3. There is an ongoing need to promote healthy swimming practices that include not swimming with diarrhea and reminding swimmers to avoid swallowing pool water to prevent waterborne disease.