An outbreak of salmonellosis in Colorado in the period July 23-August 5, 1976, has been epidemiologically traced to pasteurized cheddar cheese served in several restaurants in the state. The cheese was produced by a plant in Horton, Kansas. Two laboratories have isolated Salmonella heidelberg from cheese produced there on July 12 and 13. All of the cheese produced by the Horton plant in July is being voluntarily recalled by its 3 distributors in Denver, and, pending further investigation, no more cheese is being shipped by the plant.

Investigators first learned of the outbreak when 160 isolates of group B salmonella were reported in a 3-week period in July and August to the Colorado Department of Health-approximately a 10-fold increase over the number seen in previous years. Of 121 salmonellae serotyped by August 16, 112 (93%) were S. heidelberg. The clinical findings in these cases consisted of diarrhea, fever, chills, and abdominal cramps lasting 2-14 days. Eighteen patients were hospitalized. About 80% of cases were less than 30 years of age; there was no sex predilection. Initial investigation revealed that the illnesses were clustered from July 23-August 5 and that most of the patients from whom salmonellae were isolated gave a history of having eaten in certain restaurants within several days before the onset of illness. Of the foods eaten by patients in these restaurants, the only food which all of the restaurants received from the same distributor was pasteurized cheddar cheese.

When items consumed by the patients were compared with items consumed by randomly selected patrons of the same restaurants, significantly more cases than controls

were found to have consumed cheddar cheese (p=.028). A comparison of rates of diarrheal illness in employees of restaurants receiving the suspect cheese and in employees of randomly selected control restaurants which did not receive the cheese confirmed the association of illness with the cheese.

The epidemiologically incriminated cheese was produced between July 2 and 17 by a plant in Horton, Kansas, and was delivered to a distributor in Denver, Colorado, on July 19 in a single shipment consisting of 796, 40-pound blocks. Each block was wrapped in brown waxed paper and was in a cardboard box. On each box was the factory number (20-498), the vat number, the date of production, and the words "Kansas Cheddar." The cheese was distributed to restaurants throughout Colorado, and smaller shipments were made to Wyoming, New Mexico, Kansas, Texas, and Nebraska, and to an Air Force Base in South Dakota. Two other distributors in Denver received smaller shipments of cheese produced in July by the Horton plant, but they did not distribute cheese outside Colorado.

Two laboratories have isolated S. heidelberg from cheese produced by the plant on July 12 and 13. Laboratory investigations by the Colorado Department of Health, the Food and Drug Administration, and CDC are continuing. Reported by E Leopardi, Pueblo City County Health Dept, Pueblo, Colorado; CD McGuire, PhD, H Morlan, J Stambaugh, TM Vernon, MD, State Epidemiologist, Colorado Dept of Health; DE Wilcox, MD, State Epidemiologist, Kansas Dept of Health and Environment; Food and Drug Administration; Epidemiologic Investigations Laboratory Br and Enteric Diseases Br, Bacterial Diseases Div, and Field Services Div, Bur of Epidemiology, CDC.

Ten cases of rubella occurred in the period March 18July 25, 1976, in tourists from Japan visiting Hawaii. None of the patients 6 females and 4 males, ranging in age from 6 to 42 had been vaccinated. One additional secondary case occurred in a 26-year-old male Hawaii resident. Details of the first 4 cases follow.

Two 17-year-old female Japanese exchange students became ill with fever, rash, and postcervical lymphadenopathy within 24 hours of arrival in Hawaii. Single convalescent titers obtained 6 days after the onset of rash were 1:40 and 1:640, respectively. IgM levels indicated recent infection in both patients. Blood tests showed that 10 of the students' 14 female traveling companions (71%) were susceptible to rubella.

The third patient was a 31-year-old airline stewardess, who developed clinical rubella 2 weeks after an extensive tour of duty in Japan and Guam. Acute and convalescent sera showed a greater than 4-fold rise in rubella antibody. The fourth patient, a 24-year-old school teacher who had been teaching in Japan for 9 months, developed fever and rash upon arrival in Honolulu. She had a greater than 4-fold rise in rubella antibody.

The Hawaii Department of Health immediately immunized family and other contacts of all cases. Only 1 secondary case occurred, despite an estimated 50% susceptibility rate among family and contacts. Because the susceptibility of the adult female population in Hawaii is marked

Hawaii

ly higher than on the U.S. mainland, the Hawaii Department of Health has advised the airline and tourist industries to recommend rubella immunization for employees having contact with the public. Over 2,200 workers from those industries have undergone serologic testing for rubella antibody. Of this number, 1,803 have been immunized.

Reported by C Ibara, BS, N Wiebenga, MD, State Epidemiologist, Hawaii Dept of Health; Field Services Div, and Quarantine Div, Bureau of Epidemiology, CDC.

Editorial Note: These cases demonstrate the value of careful surveillance for rash illnesses. Rubella presents a unique problem in Hawaii. Prior to vaccine availability, susceptibility levels in all age groups were markedly higher than in the continental United States. An excellent program of vaccination, begun in 1969, as well as strict enforcement of a school entry law requiring rubella (and other) vaccines, and intensive surveillance activities have effected excellent control of rubella 64 reported cases in 1974 and 39 in 1975. Nevertheless, the susceptibility rates in persons past the age of puberty in or since 1969, the time of vaccine availability, still remains high. Although more than 95% of school-aged children are immunized, recent serologic surveys show that approximately 50% of adults native to Hawaii have no demonstrable antibodies to rubella.

The Bureau of Laboratories, CDC, has identified 2 penicillinase-producing isolates of Neisseria gonorrhoeae, obtained from a patient in Maryland and a patient in California, who were first seen in February and April 1976, respectively. Both remained symptomatic after receiving 4.8 million units of aqueous procaine penicillin G with 1 gram of probenecid and were treated with a variety of regimens before responding to spectinomycin. Further epidemiologic and clinical data are being obtained.

Reported by WA Ashford, Col. RN Lucas, and Col. MB Miller, David Grant Medical Center, Travis Air Force Base, California; J Chin, MD, State Epidemiologist, California State Dept of Health; WJ Marek, MD, St. Mary's County, and KH Acree, MDCM, State

Epidemiologist, Maryland State Dept of Health and Mental Hygiene; Bur of Laboratories and Bur of State Services, CDC. Editorial Note: This appears to be the first time that penicillinase-producing gonococci have been isolated from patients, and a search for additional cases is being undertaken. CDC recommends that all patients with gonorrhea be cultured 7 to 14 days after completion of treatment to confirm cure. Patients with a positive culture should be re-treated with 2 grams of spectinomycin intramuscularly. If prior arrangements have been made, gonococcal isolates for penicillinase testing may be sent to the Bureau of Laboratories, CDC, through state health department laboratories.

Current Trends

The first reported outbreak of St. Louis Encephalitis in the United States in 1976 has occurred in Tuscaloosa County, Alabama. As of August 20, the county reported 2 confirmed and 8 presumptive cases with onset of illness between July 15 and August 1.* Clinically, 9 of the 10 patients had encephalitis; the youngest had aseptic meningitis. The patients ranged in age from 14 to 85, with a median age of 62. Eight resided in a 2-square mile, lower socioeconomic section of southwestern Tuscaloosa city. The other 2 cases lived about 4 and 5 miles, respectively, outside the city. Over 30 suspect cases remain under investigation.

Beginning in late July, the city of Tuscaloosa, with the recommendation of the West Alabama District Health

*A confirmed case has a 4-fold change in serum antibody titers to St. Louis Encephalitis virus. A presumptive case has a complement fixing antibody titer > 1:16 and/or a hemagglutination inhibition antibody titer > 1:80.

Department, intensified vector control activities. By August 18, almost no adult vector mosquitoes were being found in the primarily affected area of the city.

As of August 20, the Alabama State Department of Health reported to CDC 1 confirmed and 1 presumptive case of St. Louis Encephalitis outside of Tuscaloosa County. Cases were also reported from California (1 confirmed), Illinois (1 confirmed), Louisiana (1 presumptive), Mississippi (4 confirmed, 5 presumptive), Ohio (1 confirmed, 1 presumptive), Tennessee (2 confirmed), and Texas (4 confirmed, 6 presumptive).

Reported by C Konigsberg, MD, MPH, Colonel G Taft, MSSE, West Alabama District Health Dept; B Helton, RN, V Johnson, FS Wolf, MD, State Epidemiologist, Alabama State Dept of Health; Medical Entomology Br, Vector Biology and Control Div, Bur of Tropical Diseases, Field Surveillance Br, Field Services Div, and Enteric and Neurotropic Viral Diseases Br, Viral Diseases Div, Bur of Epidemiology, CDC.