Pneumonia and influenza mortality from 121 cities in the United States has exceeded the epidemic threshold because of excess mortality in the New England and Middle Atlantic regions (Figure 2). The remaining regions of the country, however, are at or near expected levels.

New Jersey: This state is experiencing widespread outbreaks of influenza in the civilian population caused by A/ Victoria virus. Increases in febrile respiratory disease at Fort Dix were noted during the last 2 weeks in January. As part of a collaborative effort of respiratory disease surveillance between the New Jersey State Health Department and Fort Dix, throat cultures were obtained February 4-6. Seven A/ Victoria-like isolates were recovered, as well as 4 isolates of a type A virus with antigenic characteristics of the viral agent of swine influenza. One of these latter virus strains was from an 18-year-old recruit who died. Postmortem findings were consistent with pulmonary viral infection. None of the cases had known contact with swine.

Viruses were originally isolated from throat swabs by allantoic/amniotic inoculation of eggs, and grew to low hemagglutination titers (HA±16). The isolates failed to react with reference antisera to current influenza A and B strains in the hemagglutination inhibition test. The presence of influenza virus was confirmed by electron microscopy, and viruses were typed as influenza A by double immunodiffusion and complement fixation tests. All 4 isolates were identified as similar to swine influenza A virus (Hsw1N1) by strainspecific HI tests. Little difference was observed between the Figure 2

PNEUMONIA-INFLUENZA DEATHS IN 121 UNITED STATES CITIES

New Jersey isolate and a swine influenza-like strain isolated from man in 1974, A/Mayo Clinic/103/74(Hsw1N1). The neuraminidase of the New Jersey isolates was also shown to be similar to that of swine influenza A virus. Antigenically similar viruses were isolated from the original throat swabs in 2 separate laboratories.

A convalescent serum was collected from 1 patient from whom a swine influenza-like virus was isolated. HI antibody titers were 1:80 to his isolate and swine influenza virus. Convalescent sera from 2 patients in the same location, from whom A/Victoria-like influenza virus had been isolated, had swine influenza HI titers of <10, and A/Victoria HI antibody titers of 1:20 and 1:320.

Mississippi: Sporadic increases in influenza-like illness have been reported by physicians in the northeastern part of Mississippi, and several schools have been closed because of absenteeism. Two isolates of A/Victoria/3/75-like strains have been obtained from individuals who became ill on January 28. Arkansas: Scattered outbreaks of influenza-like illness have been reported. Influenza A virus has been isolated from cases occurring in the first week in February.

Washington, D.C.: Scattered outbreaks with increased school absenteeism occurred in late January. Influenza A virus was isolated.

(Reported by M Goldfield, MD, R Altman, MD, State Epidemiologist, New Jersey Dept of Health; J Bartley, Col, Health and Environment, USAMEDDAC, Ft Dix, New Jersey; T Nowosiwsky, Col, Div of Preventive Medicine, PK Russell, Col, Div of Communicable Disease and Immunology, FH Top, Jr, Col, Dept of Virology, Walter Reed Army Institute of Research, Washington, DC; D Blakey, MD, State Epidemiologist, Mississippi Board of Health; AG Dean, MD, Acting State Epidemiologist, Arkansas Board of Health; C Brandt, PhD, Children's Hospital Nutritional Medical Center, Washington, DC; W Jordan, MD, B Omer, MD, JR Pate, MD, Acting State Epidemiologist, District of Columbia Community Health & Hospital Admin; LJ Legters, Col, Health and Environment, Office of the Surgeon General Headquarters, Dept of the Army, Washington, DC; Virology Div, Bur of Laboratories, and Viral Diseases Div, Bur of Epidemiology, CDC.)

Editorial Note

Antibodies to the swine influenza virus are found in many persons over the age of 50, suggesting that antigenically similar viruses were widespread in the human population at least up through 1930. There is some evidence from antibody prevalence studies that occasional infections with swine influenza virus may have occurred in more recent years among persons in frequent contact with swine.

The recovery in New Jersey of agents antigenically similar to swine influenza virus comes after the isolation of a similar virus from the lungs of a 16-year-old boy with fatal Hodgkins disease in Minnesota in 1974 (1). A confirmed rise in swine influenza virus antibody titers has recently been documented in an 8-year-old boy from Wisconsin in 1975.

To date, all other reported A isolates from the Continental United States have been A/Victoria-like. Because of the difficulty of characterizing the swine virus in the laboratory, some isolates may have been unrecognized as such. To determine if the A swine virus is causing other influenza in

PITCAIRN ISLAND

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Insert: Americas: USA, Canada.

Erratum, Vol. 24, No. 44, p 379

In the article, "Powassan Virus Isolated from a Patient with Encephalitis New York," the statement in the editorial note that "only 1 human case has previously been reported from the United States" is incorrect.

In addition to this 1 previous case, 3 other cases from the United States have been described. One case occurred in a New Jersey resident in 1970 (1) and 2 cases in upstate New York residents in 1972 (2). References

1. Goldfield M, Austin S, et al: A nonfatal human case of Powassan Virus Encephalitis. Am J Trop Med Hyg 12:78-81, 1973

2. Smith R, Woodall J, et al: Powassan Virus infection: A Report of three human cases of encephalitis. Am J Dis Child 127:691-693, 1974

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