Figure 1: Photomicrograph of a positive leptospiral microscopic agglutination test (MAT) with live antigen using darkfield microscopy. Source: US Centers for Disease Control and Prevention.
The largest US outbreak occurred during a combination of two international triathlon events with more than 1,500 registered participants that featured 1.5 mile lake swims held in consecutive months in Illinois and Wisconsin dur- ing the summer of 1998. 1 Of 639 single or combined event participants interviewed by telephone, 74 had illnesses consistent with the case definition of LS that included fever with or without chills, headache, myalgia, abdominal pain, eye pain, red eyes, or diarrhea during themonth-long period encompassing the two events for an attack rate of 12%. The median age of probable cases was 36 years; 80%were males, and 54 of 74 case-patients sought medical attention (73%), of whom 21 (39%) were hospitalized. Among hospitalized patients, two patients manifested jaundice and acute renal failure requiring hemodialysis (Weil’s disease), and two underwent exploratory laparotomies for acute abdomens. Acute-phase serum samples from several triathletes were positive for LS by enzyme-linked immunosorbent assay (ELISA) IgM dipstick tests. As a result of the outbreak, public health authorities temporarily closed the lake in which triathletes participated to swimming, water-skiing, and personal watercraft use for further testing. Leptospirosis Outbreak 2: Leptospirosis After Flooding of a University Campus - Hawaii, 2004 (Adapted from MMWR , February 10, 2006) 4 On October 31, 2004, heavy rains in the Honolulu area caused a stream adjacent to the University of Hawaii to overflow its banks and flood the campus with six or more inches of standing water. Although the university was evacuated and the campus was closed temporarily, clean-up by faculty, students, staff, contractors, and National Guard troops began immediately. During the period of October
31-November 2, 2004, a 56-year-old genetics professor waded throughout his flooded laboratory in sandals and developed blisters on his feet. On November 10, 2004, he developed fever, chills, nausea, and vomiting. Although his fever subsided over the next four days, he developed tremor, poor balance, and visual scotomata. He presented to a local emergency department and was hospitalized for empiric treatment of probable LS with oral doxycycline. Later, both an ELISA IgM dipstick test and a convalescent serum microscopic agglutination test (MAT) were positive for Leptospira IgM antibodies (Figure 1). On suspicion of a leptospirosis outbreak, the university and state health de- partment established an immediate Internet-based febrile disease surveillance system among all persons on campus during the flooding. Persons reporting febrile illnesses after contact with floodwaters were offered free ELISA testing for leptospirosis. A total of 271 persons responded to the Inter- net survey, with 90 (33%) reporting febrile illnesses within 30 days of floodwater contacts. Forty-eight respondents met the case definitions for suspected LS; and all 48 were tested for LS by ELISA IgMdipsticks, in addition to another 32 floodwater-contact victims requesting testing. Of the 80 floodwater-exposed persons tested, only one additional case of leptospirosis was detected in a 27-year-old gradu- ate student (Case 2) who assisted the index-case professor (Case 1) in his lab over the period October 31-November 4 and lacerated his foot during flood clean-up. The graduate student reported fever, chills, headache, nausea, vomiting, and diarrhea within 10 days of his first floodwater contact but recoveredwithout treatment within a week. Authorities concluded that both patients were at risk for LS by wading in contaminated floodwaters in sandals with open wounds on their feet.
J La State Med Soc VOL 166 September/October 2014 187
Made with FlippingBook - Online catalogs