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An outbreak of Escherichia coli O157 :H7 infections occurred after a graduation banquet at a university in Wisconsin. Sixty-one (32%) of 193 banquet attendees developed a gastrointestinal illness ; 2 were hospitalized, none developed hemolytic-uremic syndrome or thrombotic thrombocytopenic purpura, and none died. The spectrum of illness was unusually mild, with 61% of ill persons reporting nonbloody diarrhea. A strain of E. coli O157 :H7, indistinguishable from the outbreak strain by toxin type, plasmid profile, and pulsed-field gel electrophoresis, was isolated from an unopened package of an uncooked round of beef from the original shipment of meat. An investigation suggested that both undercooked roast beef and salad cross-contaminated with beef were vehicles of transmission. These findings demonstrate that meat from beef cattle may transmit E. coli O157 :H7, and such infections among young to middle-aged adults may be mild and may often go undetected.

The epidemiologic features and clinical spectrum of pertussis in the elderly are poorly understood. In October 1985, the Wisconsin Division of Health investigated an outbreak of pertussis in residents of a nursing home in rural Wisconsin. Clinical information and nasopharyngeal swab and acute- and convalescent-phase serum specimens were obtained from all consenting residents and employees. Of 105 residents, 38 (36.2%) were seropositive, including four who were culture-positive for Bordetella pertussis. Culture-positive residents (age range, 52-81 years) had cough lasting 43-54 days. Three of these residents had paroxysmal cough, and all four had cough that interrupted sleep; none of the residents had cough with apnea or vomiting, and all recovered without sequelae. Of six seropositive residents with clinical pertussis, five lived on the south wing of the facility. Of 104 employees, 8 (7.7%) were seropositive, but none were culture-positive for B. pertussis. The higher attack rate for residents and the clustering of clinical cases were consistent with ongoing transmission within the nursing home.

Ninety-five persons exposed to a point-source of Blastomyces dermatitidis in Wisconsin in 1984 were evaluated 3 months after exposure for the development of specific cellular immunity, and the 48 infected persons were again evaluated 7 and 21 months after exposure. The immune response was assessed by an assay of [3H]thymidine uptake by lymphocytes proliferating in response to stimulation with Blastomyces alkali- and water-soluble antigen (B-ASWS) or blastomycin and by skin testing with blastomycin. At 3 months, 36 (84%) of 43 patients demonstrated a proliferative response to B-ASWS (mean value of experimental [E]-control [C] counts, 16,852 +/- 2664, and of E/C, 42.2 +/- 5.3). None of the patients demonstrated a proliferative response to blastomycin, and only 19 (41%) of 45 patients tested had a positive blastomycin skin test. By 21 months, 47 (98%) of the 48 patients demonstrated a proliferative response to B-ASWS on at least one testing date. Of those initially positive, 82% had a persistently positive proliferative response at 21 months; mean E-C and E/C values were comparable to those seen at 3 months. None of the 47 uninfected persons demonstrated a proliferative response to B-ASWS: 7 with positive histoplasmin skin tests had a mean E-C value of 1094 +/- 432, and the 40 others, a mean value of 1139 +/- 212. A proliferative response to B-ASWS in exposed individuals is a reliable marker of specific cellular immunity in blastomycosis and the response persists in most patients for up to at least 2 years.

Clinical and laboratory findings were examined in 80 nonfatal cases of toxic-shock syndrome (TSS) which occurred in women from Minnesota, Wisconsin, and Iowa between October 1, 1979, and September 19, 1980. Among the clinical and laboratory factors reviewed, the presence of physician-diagnosed shock was the factor that most significantly correlated with other organ involvement. Vomiting, mucous membrane hyperemia, myalgias, and abnormal urinalysis were the factors noted to be manifest as frequently in the absence as in the presence of shock. Twenty-seven patients had recurrent episodes of TSS. The use of antistaphylococcal antibiotics during the initial TSS episode and the subsequent discontinuation of tampon use were independently statistically significantly associated with a decreased risk of recurrent illness. Only 44 of 54 patients had cervical/vaginal cultures positive for Staphylococcus aureus, a result indicating that a negative cervical/vaginal culture does not preclude the diagnosis of TSS.

Lyme disease is a tick-borne illness that has been reported from three regions in the United States--the Northeast, Midwest, and West--which correspond to the distribution of the recognized vectors of the disease, Ixodes dammini and Ixodes pacificus. In 1982, a surveillance system designed to define the morbidity and geographic distribution for Lyme disease by using a clinical case definition received information on 491 definite cases and 38 probable cases. Of the definite cases, 489 were acquired in endemic areas of the Northeast or Midwest; one case was acquired in Utah and one in western Pennsylvania, two areas where the illness had not been previously reported. Three states that previously had not reported cases of Lyme disease (Kentucky, Indiana, Montana) reported probable cases. In 37% of the definite cases, the patients had neurological symptoms (most commonly reported was headache with stiff neck, suggestive of meningitis), 10% cardiac symptoms (most commonly reported was palpitations), and 54% arthritic symptoms (most commonly reported in large joints). The occurrence of Lyme disease in areas outside the currently recognized endemic regions, as well as the recent description of Amblyomma americanum as a probable vector, suggest that additional vectors may be described in the future.

During an outbreak of pertussis in residents and staff of a facility for the developmentally disabled, 149 persons had laboratory evidence of Bordetella pertussis infection; 130 (87%) reported respiratory illness. Infection rates (IR) in affected wards ranged from 6% to 91%. Most residents were adolescents and adults and had received a full course of diphtheria-tetanus toxoids-pertussis (DTP) vaccine; IRs increased with increasing time after the last DTP dose in fully vaccinated residents. The IR was lower in residents on wards where erythromycin treatment/prophylaxis was started two or fewer weeks after the onset of illness in the first case on the ward (IR, 16%), compared with four or more weeks after onset (IR, 75%; P less than 10(-6)). Respiratory symptoms were milder in ill residents treated within seven days of onset of illness. Although B. pertussis transmission was substantial, erythromycin treatment of patients and prophylaxis of exposed persons was effective in decreasing transmission and disease severity. Carbamazepine toxicity occurred in seven (19%) of 37 residents when carbamazepine was administered with erythromycin.

At 22 hr after an uncomplicated delivery of a healthy full-term infant, a 26-year-old woman developed toxic-shock syndrome (TSS). A vaginal culture yielded a coagulase-positive Staphylococcus that produced staphylococcal enterotoxin F (SEF) but no other enterotoxins. Breast milk specimens obtained on postpartum days 5, 8, and 11 contained 3.0, 2.5, and 2.0 ng of SEF/ml, respectively. Sera obtained from the mother on postpartum days 4 and 38 had titers (by radioimmunoassay) of antibody to SEF of 1:5 and less than 1:5, a result demonstrating a persisting lack of antibody to SEF after the first episode of TSS; the infant's serum titer of antibody to SEF on day 38 was also less than 1:5. Further longitudinal monitoring of SEF and antibody to SEF in breast milk from this patient is presented. This case is the first isolation of SEF from a body fluid obtained from a patient with TSS further strengthens the association between SEF and TSS.

Enzyme immunoassay (EIA), immunodiffusion (ID), and complement fixation (CF) tests for antibody to the A antigen of Blastomyces dermatitidis were assessed in 47 patients in an epidemic of blastomycosis and in 89 control subjects with lower respiratory tract illness. Antibody was detected by EIA, ID, and CF in 77%, 28%, and 9% of the patients, respectively. EIA titers ranged from 1:8-1:512 (median titer, 1:128). Antibody detected by ID or CF was always detectable by EIA. Antibody was detected by EIA 13 days after illness onset, and the peak seroprevalence rate and geometric mean titer occurred 50-70 days after onset. Antifungal therapy produced a significant decline in antibody titer by approximately six months after onset. Seven (8%) control subjects had detectable antibody, six had EIA titers of 1:8, and one had a titer of 1:16. The specificities for EIA, ID, and CF were 92%, 100%, and 100%, respectively. The EIA provides a significant advance in serodiagnostic testing for blastomycosis and can be used in an outbreak setting as an epidemiological tool to identify acute B. dermatitidis infection; titers greater than or equal to 1:32 strongly support the diagnosis, whereas titers of 1:8 or 1:16 are suggestive.