A questionnaire was administered by telephone or mail to 136 (98%) of the 139 persons identified as having attended the conference. Cases were defined as persons with acute onset of sore throat between May 31 and June 5, who had had no antecedent contact to household members with pharyngitis. Severity of illness ranged from minor discomfort to symptoms resulting in several days' absence from work. Positive cultures for group A streptococci were reported for 13 (93%) of 14 individuals from whom throat cultures were obtained. However, none of the cultures were still available for typing or confirmation by the time of investigation. The survey implicated a luncheon held May 31. Sixty (57%) cases among the 106 persons who attended it were identified, compared with no cases among 30 conference attendees who did not attend the luncheon (p < 0.0001). Food-specific attack rates suggested macaroni salad or mousse as possible vehicles of transmission. The attack rate for persons who ate macaroni salad was 88%, compared with 47% for those who did not (p < 0.0001), but only one-third of persons who were ill gave histories of having eaten macaroni salad. The attack rate for persons who ate mousse was 63%, compared with 39% for persons who did not (p 0.053), and, since 82% of ill persons reported having eaten the mousse, it was considered more likely if only one vehicle were involved. The incubation period of the illness was 24-36 hours (median 36 hours).

=

All the food for the luncheon was prepared by five hotel employees. The foodhandlers were interviewed and examined, and cultures were obtained. All were negative for group A streptococci, and no visible skin lesions were found on any worker. One worker claimed to have had a sore throat the day of the luncheon but did not seek medical attention.

The pastry chef had prepared two types of mousse the morning of the luncheon. Although it was refrigerated for 30 minutes during one phase of preparation, the final product was kept at room temperature for 1-2 hours before the luncheon.

Reported by JG Rigau, MD, Commonwealth Epidemiologist, Puerto Rico Dept of Health; T Martin, V Gibson, D Giedinghagen, GL Hoff, PhD, Div of Communicable Disease Control, Div of Environmental Health, Kansas City Health Dept, HD Donnell, Jr, MD, State Epidemiologist, Missouri Dept of Social Svcs; Respiratory and Special Pathogens Epidemiology Br, Div of Bacterial Diseases, Center for Infectious Diseases, CDC.

Editorial Note: Before the advent of pasteurization of milk and availability of adequate refrigeration, foodborne streptococcal outbreaks were very common. Outbreaks resulting in epidemics of scarlet fever, rheumatic fever, and suppurative complications were reported. Improvements in sanitation have resulted in foodborne streptococcal outbreaks becoming relatively uncommon (1-3).

These outbreaks show the difficulties involved in recognizing foodborne illness. Foodborne transmission of streptococci, rather than person-to-person transmission, is suggested by a large clustering of cases, a shorter incubation period, and a higher attack rate. Unless disease occurs in a setting where people who are ill are likely to notice the epidemic themselves, it is difficult for public health officials to detect the increased incidence of streptococcal pharyngitis in the community, especially since only a small percentage of persons with sore throats seek medical attention and ultimately receive treatment for the illness. The Puerto Rico outbreak was recognized only because a number of ill people worked in the same office. Initially, the party attendees felt the illness resulted from close person-to-person contact; only when persons who were not at the party ate party food and became ill did the office manager notify the health department. The second outbreak almost escaped detection, since the illness peaked after the conference had ended, and the participants had returned to their homes in seven states.

Streptococcal Foodborne Outbreaks – Continued

It is unknown how many cases of endemic streptococcal pharyngitis are caused by foodborne transmission. It is important to recognize that rheumatic fever and glomerulonephritis may result from outbreaks of these infections.

References

1. Hill HR, Zimmerman RA, Reid GV, et al. Food-borne epidemic of streptococcal pharyngitis at the United States Air Force Academy. N Engl J Med 1969;280:917-21.

2. McCormick JB, Kay D, Hayes P, Feldman R. Epidemic streptococcal sore throat following a community picnic. JAMA 1976;236: 1039-41.

3. Ryder RW, Lawrence DN, Nitzkin JL, et al. An evaluation of penicillin prophylaxis during an outbreak of foodborne streptococcal pharyngitis. Am J Epidemiol 1977;106:139-44.

International Notes

Quarantine Measures

The following change should be made in the "Health Information for International Travel," Supplement to the MMWR, Vol. 33, 1984.

The Morbidity and Mortality Weekly Report is prepared by the Centers for Disease Control, Atlanta, Georgia, and available on a paid subscription basis from the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402, (202) 783-3238

The data in this report are provisional, based on weekly reports to CDC by state health departments. The reporting week concludes at close of business on Friday; compiled data on a national basis are officially released to the public on the succeeding Friday.

The editor welcomes accounts of interesting cases, outbreaks, environmental hazards, or other public health problems of current interest to health officials. Such reports and any other matters pertaining to editorial or other textual considerations should be addressed to: ATTN: Editor, Morbidity and Mortality Weekly Report, Centers for Disease Control, Atlanta, Georgia 30333.

of Michigan

MMWR

MORBIDITY AND MORTALITY WEEKLY REPORT

Current Trends

December 7, 1984 / Vol. 33 / No. 48

673 Measles

Weeks, 1984

681 Dermatitis among Hospital Workers Oregon

682 Sporotrichosis Among Hay-Mulching Workers Oklahoma, New Mexico

During the first 39 weeks of 1984, a provisional total of 2,322 measles cases was reported in the United States (incidence rate 1.0/100,000 population) (Figure 1). This is an 84.3% increase from the 1,260 cases reported during the same period in 1983 (0.5/100,000). Of the total, 1,620 cases (69.8%) were reported from five states- Texas (509), Michigan (462), California (308), Illinois (178), and Hawaii (163). Eleven states (California, Hawaii, Idaho, Illinois, Michigan, New Hampshire, New Mexico, Texas, Utah, Vermont, Washington) and New York City had incidence rates of 1.0/100,000 population or higher.

Although the overall incidence rate increased, the number of states reporting measles was similar to the number reporting during the same period of 1983. Seventeen states reported no measles cases (indigenous or imported), compared with 16 states and the District of Columbia during the same period in 1983. However, the increase in cases was associated with an increase in the number of counties affected. In 1984, 183 (5.8%) of the nation's 3,139 counties reported measles cases during the first 39 weeks, compared with 115 (3.7%) during the same period in 1983.

FIGURE 1. Reported measles cases - United States, 1982-1984

Measles - Continued

Two hundred sixty-two cases (11.3%) were associated with international or out-of-state importations-an average of 6.7 cases per week-compared with 220 (17.5) cases during the same period in 1983 (1).

During the first 39 weeks, detailed information was provided to CDC's Division of Immunization on 2,321 cases. Of these, 2,277 (98.1%) met the standard clinical case definition for measles,† and 919 (39.6%) were serologically confirmed. In most cases, onset of rash occurred from weeks 9 through 21, peaking at week 14 (134 cases) (Figure 2).

The age characteristics of reported cases changed from 1983 to 1984 (Table 1). In 1983, the highest incidence rates were reported for preschoolers. In contrast, the rates for the first 39 weeks of 1984 were highest for children 10 years to 14 years of age, who had a more than threefold increase in incidence rates, compared with the total for 1983. Of the 569 preschoolers who had measles in 1984, 155 (27.2%) were under 12 months of age; 114 (20.0%) were 12-14 months of age; 38 (6.7%) were 15 months of age; and 262 (46.0%) were 16 months to 4 years of age. Persons 12-14 months of age accounted for 4.9% of the 2,321 cases.

Of the 2,321 cases, 819 (35.3%) were classified as preventables (1) (Table 2). The highest proportion of preventable cases occurred among persons who were not of school age. Almost 75% of the cases among children 16 months to 4 years of age and adults 20-24 years of age were preventable. Although more than half the preventable cases occurred

*The difference between this number and the 2,322 cases reported to MMWR reflects delays in reporting.

*Clinical case definition is fever (38.3 C [101 F] or higher, if measured), generalized rash of 3 days' duration or longer, and at least one of the following: cough, coryza, or conjunctivitis.

§A case is considered preventable if measles occurs in a U.S. citizen: (1) at least 16 months of age, (2) born after 1956, (3) lacking adequate evidence of immunity to measles (documented receipt of live measles vaccine on or after the first birthday and at least 2 weeks before onset of illness or physiciandiagnosed measles or laboratory evidence of immunity), (4) without a medical contraindication to receiving vaccine, and (5) with no religious or philosophic exemption under state law.

FIGURE 2. Reported measles cases, by week of rash onset weeks, 1984

14 16 18 20 22 24 26 28 30 32 34 36 38 ONSET (WEEK NUMBER)

Measles - Continued

among persons 5-19 years of age, only 31.4% of cases occurring in that age group were considered preventable. The proportion of preventable cases in this group increased progressively with increasing age.

Reported by Div of Immunization, Center for Prevention Svcs, CDC.

Editorial Note: The increased number of cases from 1983 to 1984 and the increased geographic distribution indicate the need for careful and continued evaluation of the measles situation in the United States. Available information does not indicate the basic elimination

TABLE 1. Age distribution and estimated incidence rates of reported measles casest United States, 1983 and first 39 weeks, 1984

'Cases per 100,000 population extrapolating those with known age to total reported cases. * Provisional data.

§Total cases reported to MMWR in 1983.

Total cases reported to CDC's Division of Immunization during the first 39 weeks of 1984.

TABLE 2. Age distribution and preventability of measles cases weeks, 1984*