2013-2014 Drinking Water-associated Outbreak Surveillance Report: Selected Outbreak Descriptions

This table provides descriptions of selected outbreaks presented in Surveillance for Waterborne Disease Outbreaks Associated with Drinking Water — United States, 2013-2014 (MMWR Weekly).

Descriptions of Selected Waterborne Disease Outbreaks Associated with Drinking Water, United States, 2013-2014
Month	Year	State/Jurisdiction in which outbreak occurred	Etiology	No. of cases (deaths)	Description of outbreak
June	2014	Florida	Legionella pneumophila serogroup 1	3	Three residents of a federal long term care facility were diagnosed with legionellosis over a 2 month period; all cases were in one of eight living units. Environmental water sample analysis conducted by the facility from multiple locations including sink, ice machine, shower, fountain, and refrigerator water tested positive for Legionella pneumophila (0.1-2.6 cfus/mL; median 1.4 cfus/mL). Chlorine levels ranged from 0.0 to 0.1 (median=0.01 ppm); hot water temperatures ranged from 105-140°F (median=128°F); cold water temperatures ranged from 65-91°F (median=86°F) during the sampling time frame. The investigation determined that automatic biocide sensing equipment malfunctioned in conjunction with stagnant water conditions that existed in dead legs prior to occupancy likely were factors contributing to the outbreak. Following remediation, the premise plumbing system was continually monitored and point of use filters along with other short term measures were utilized until the water system was cleared of Legionella. The facility operators continued to develop, improve and implement their water management program.
August	2014	Florida	Legionella pneumophila serogroup 1	6	Six individuals developed legionellosis (3 confirmed; 3 probable) following exposures at a hotel over a 9 month period. Among the ill individuals was a staff member who spent time in multiple areas of the hotel. All six cases reported exposures to the premise plumbing system via showering or maintenance activities. Four cases reported exposure to an indoor spa. The investigation determined that the hot water temperatures of the premise plumbing ranged from 99-122°F (median=107°F); cold water temperatures were 81-82°F (median=82°F); chlorine was 0.2 ppm throughout the facility. The spa was determined to be operating within acceptable biocide ranges. Following thermal remediation, the water system was monitored to ensure proper temperatures, pH and biocide levels in the systems for a period of one year.
September	2014	Idaho	Giardia duodenalis	2	Two people became ill following consumption of drinking water at a hotel. A boil water advisory was in effect; however, the ill persons were not aware of that until after they consumed the water. This highlights a gap in communications surrounding boil water advisories and a need to ensure persons at risk are informed.
February	2013	Maryland	Nitrite	14	Fourteen office workers developed multiple symptoms of illness including vomiting, headache, dizziness, fatigue, rash, confusion, palpitations, or loss of consciousness following the unintentional addition of a corrosion inhibitor (39% sodium nitrite) to the hot water system instead of to the heating and cooling system. Cases had methemoglobin levels ranging from 1.6-32.3%. Water samples as well as cream of wheat and oatmeal prepared with the water and consumed by some cases were tested for both nitrite and combined nitrate and nitrite. Elevated concentrations were found in the potable hot water system, in mixed hot/cold lines, and in the leftover food.
July	2014	Montana	Norovirus Genogroup II	62	At least 62 people from 10 states became ill during a waterborne disease outbreak of norovirus at a resort in Montana. After cleaning and sanitizing all of the rooms failed to prevent additional illnesses, water testing was conducted to address the possibility of waterborne transmission. One of three well water samples tested positive for Escherichia coli. These results indicated fecal contamination and led to additional testing for norovirus. Water samples collected and sent to CDC were determined to contain the same Genogroup II strain. All of the ill guests were identified as either staying in a cabin supplied by the contaminated well or eating or drinking at the main lodge which used water from the contaminated well. The resort had multiple septic systems, including one that was unpermitted and for which records about exact location and other details were not available. The environmental health investigation determined that the resort met the conditions to be reclassified from an individual water system to a Public Water Supply, leading to additional regulation and monitoring of drinking water quality.
September	2013	Ohio	Cyanobacterial toxin	6	A drinking water operator detected microcystins in finished drinking water. The toxin in the water came from a cyanobacterial bloom in western Lake Erie, the raw source water for the drinking water system. The health department was notified that water samples exceeded the Ohio EPA allowable maximum level (1.0 ug/L) and A ‘Do Not Drink’ advisory was issued. The next day a health advisory was issued to medical providers, hospital infection control practitioners, and veterinarians to warn about potential exposures and HAB-associated illnesses. Six cases of illness were identified. This is the first HAB-associated drinking water outbreak reported in NORS.
August	2014	Ohio	Cyanobacterial toxin	110	A municipal drinking water utility that uses water from Lake Erie tests for cyanobacteria toxin at the location of the water intake during algal bloom season on the lake, usually beginning late July or early August. This water treatment plant reported a microcystin level above the 1.0 ppb allowable standard for drinking water set by the Ohio EPA. The local Emergency Management Agency sent out ‘Do Not Touch’ and ‘Do Not Drink’ advisories for users of the water system that remained in effect for 56 hours, until levels of microcystin returned to below 0.5 ppb. An extensive emergency response occurred to ensure that the approximately 500,000 people affected had access to safe drinking water and information about the advisory. Local and state health departments worked together to identify and survey individuals matching the case definition who reported illness to local emergency departments (n=110). Of the 110 cases identified and attempted to survey by phone, 28 responses were received. The following month, state, local, and federal public health partners collaborated to evaluate the public health response through a Community Assessment for Public Health Emergency Response (CASPER) survey, which provided valuable information about communications, needs, and health concerns during and following the drinking water advisory. This was the first time that this survey methodology had been used in response to a microcystin contamination event in a drinking water system.
October	2014	Ohio	Cryptosporidium (S)	100	One hundred people became ill with gastrointestinal symptoms following a wedding held in a barn at an apple orchard. After being notified by a guest of the illnesses six days later, the health department followed up to determine the source of illness. Through interviews with attendees and staff, it was found that the family used a non-potable water tap to make beverages. The owner of the venue had not intended the tap water to be used for human consumption and while he verbally told members of the family, there were no signs posted. This water originated from an untreated spring open on the side of a hill and was pumped into the barn. Water from the spring and kitchen sink in the barn was tested and determined to be positive for total coliform and Cryptosporidium parvum. Guest interviews revealed that only the ill guests drank water or beverages containing water from the suspected tap and the others did not. The environmental investigation in this outbreak was crucial to determining the source of illness as there were no clinical isolates available.