A jet airliner with 54 persons aboard was delayed on the ground for three hours because of engine failure during a takeoff attempt. Most passengers stayed on the airplane during the delay. Within 72 hours, 72 per cent of the passengers became ill with symptoms of cough, fever, fatigue, headache, sore throat and myalgia. One passenger, the apparent index case, was ill on the airplane, and the clinical attack rate among the others varied with the amount of time spent aboard. Virus antigenically similar to A/Texas/1/77(H3N2) was isolated from 8 of 31 passengers cultured, and 20 of 22 ill persons tested had serologic evidence of infection with this virus. The airplane ventilation system was inoperative during the delay and this may account for the high attack rate.

Yupik Eskimos of southwestern Alaska have the highest known prevalence of hepatitis B virus infection of any general population in the United States. Prospective serological surveys of 1,280 seronegative Yupik Eskimos, performed between 1971 and 1976, identified 189 (14.8%) who developed serological evidence of hepatitis B virus infection. Twenty-six (13.8%) developed clinical hepatitis during the interval when seroconversion occurred. The proportion of patients with clinically apparent hepatitis increased with age (P less than .01), ranging from 9.5% of infections in patients who were four years of age or less to 33.3% of infections in patients who were 30 years of age or older. Twenty-five (13.3%) of the 188 individuals who were studied became chronic carriers of hepatitis B surface antigen. The risk of becoming a carrier was inversely related to the age of the patient at the time of infection (P = .02). Among patients who were four years of age or less when infected, 28.8% became chronic carriers of hepatitis B, as compared with 7.7% of those who were 30 years of age or older.

One hundred fifty asymptomatic patients who were carriers of hepatitis B surface antigen (HBsAg) were studied serologically for up to 11.3 years (mean, 6.1 years). Only 9 (6.0%) lost HBsAg during the study period, for a mean annual clearance rate of 1.0%. We found no difference in the clearance of HBsAg by age, but a higher percentage of females lost HBsAg than did males (P less than .02). Hepatitis B e antigen (HBeAg) was found in 102 (68.5%) of the 149 carriers of HBsAg who were tested. Carriers of HBsAg who were seropositive for HBeAg were younger than those who were seronegative for HBeAg (P less than .01). The prevalence of HBeAg was not affected by the patients' sex. The clearance of HBeAg was gradual; 9.6% of the HBsAg carriers lost HBeAg each year. Females were more likely to clear HBeAg than were males (P less than .01), and those who cleared HBeAg were older than those who did not (P less than .01). Three (2.0%) of the HBsAg carriers developed primary hepatocellular carcinoma during the study period.

In a previous study we demonstrated that Alaskan Eskimos had the highest endemic incidence of invasive Haemophilus influenzae type b (Hib) disease. In 1980 we established a prospective surveillance program for all invasive Hib disease throughout Alaska to characterize additional epidemiological features of disease in Native Alaskans to plan for a vaccine efficacy trial and define the epidemiology of Hib disease in all population groups in the state. For the three-year period, 1980-1982, 287 confirmed episodes of invasive Hib disease occurred. For children less than five years of age, the incidences for Eskimos, Indians, and non-Natives were 705, 401, and 129 cases per 100,000 population, respectively. The Native population represents only 16% of the population of Alaska but has 51% of all invasive Hib disease. Disease differed significantly among Eskimos, Indians, and non-Natives with regard to risk, age of onset, disease type, antibiotic susceptibility of strains, and regional incidence, but mortality and seasonal occurrence were similar. For Native Alaskans the cumulative Hib disease risk for the first two years of life was 4% (range, 1%-7% by region). This high endemic disease risk, concentrated in the first two years of life, provides a unique opportunity to prospectively evaluate the protective efficacy of a vaccine in a randomized, blinded, and placebo-controlled trial. Such a trial was initiated in December 1984.

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