Swine-Origin Influenza in Humans: Historical Perspective
Last updated December 16, 2010. At the current time, this content is considered historical and will not be updated until further notice.
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Cases Identified in Civilians Before the 2009-2010 Pandemic
Swine-Origin Influenza Outbreak at Fort Dix, New Jersey, 1976
The US Swine-Origin Influenza Vaccination Campaign, 1976
Cases Identified in Civilians Before the 2009-2010 Pandemic
A 2007 report identified 37 civilian swine-origin influenza cases reported in the medical literature from 1958 through 2005 (Myers 2007). Of these cases, 19 occurred in the United States, 6 in Czechoslovakia, 4 in the Netherlands, 3 in Russia, 3 in Switzerland, 1 in Canada, and 1 in Hong Kong. Twenty-two of the 36 for whom data were available (61%) reported recent exposure to pigs. The overall case-fatality rate was 17%. Limited human-to-human transmission was reported in several situations.
From December 2005 to February 2009, 11 sporadic cases of infection in humans with triple-reassortant swine influenza A H1 viruses were reported to the Centers for Disease Control and Prevention (CDC) (Newman 2008, Shinde 2009).
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Ten of the infections were caused by triple reassortant H1N1 viruses and one by triple reassortant H1N2 virus.
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Seven cases involved either direct exposure to pigs or close proximity to pigs (ie, within 6 feet) shortly before illness onset. In two other cases the patients were in the general vicinity of pigs before illness onset, one was epidemiologically linked to a possible case, and one had no pig exposure.
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Among the 10 patients with known clinical symptoms, nine reported fever, all had cough, six had a headache, and three reported diarrhea. All patients survived the illness, although four were hospitalized and two required mechanical ventilation.
An additional swine-origin influenza case occurred in Spain in 2008 (Adiego 2009, Van Reeth 2009).
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Swine-Origin Influenza Outbreak at Fort Dix, New Jersey, 1976
An outbreak of swine-origin influenza was recognized in early 1976 among military personnel at Fort Dix, New Jersey. Thirteen clinical cases occurred with one death; the cause of the outbreak remains unknown, and no exposure to pigs was identified (Gaydos 2006). Retrospective serologic testing subsequently demonstrated that up to 230 soldiers had been infected with the novel virus, which was an H1N1 strain. The outbreak did not spread beyond Fort Dix.
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The US Swine-Origin Influenza Vaccination Campaign, 1976
Following the Fort Dix outbreak, the federal government embarked upon a universal vaccination campaign aimed at vaccinating the United States population against the H1N1 swine-origin influenza strain because of concerns that it could cause a pandemic (Sencer 2006). A vaccine was developed and vaccinations began in the fall of 1976. By late in the year, more than 40 million Americans had been vaccinated. Soon after vaccinations began, however, reports of Guillain-Barre syndrome (GBS) associated with vaccination began to surface. By December 1976, the federal government decided to halt the vaccination campaign since no evidence of H1N1 transmission had been detected during the course of the year and there was concern regarding an association between GBS and the H1N1 vaccine. A subsequent epidemiologic study demonstrated a slightly elevated risk for acquiring GBS among persons who received the H1N1 swine-origin influenza vaccine (Schonberger
1979)
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