Outbreak Of Influenza-like Illness Research Articles

Mixed outbreak of parainfluenza type 1 and influenza B associated with tourism and air travel

Background: A preseasonal outbreak of influenza-like illness was reported in a tourist group that had returned from Ireland to the United States on October 1 and 2, 1999. The authors investigated to determine the timing, extent, and nature of the outbreak. Methods: A cohort study was conducted among the entire group. Cases were defined as illness occurring among tour members who experienced cough or sore throat with onset from September 29 through October 5. Nasopharyngeal and throat cultures were examined for respiratory viruses. Results: Eighteen (60%) of the 30 tourists were ill; the majority (66%) of cases had onset of illness within 1 day of departure from Ireland. Human parainfluenza virus type 1 was isolated from six cultures, and influenza B from three. The attack rate was 100% among the eight persons 65 years of age or older versus 45% among the 22 persons younger than 65 years (P = 0.01). Conclusion: International travellers, particularly older persons and members of organized tour groups, may experience increased risks for respiratory viral infection. and containment of imported infectious diseases depend on prompt reporting and epidemiologic investigation.

Three Summertime Outbreaks of Influenza Type A

In the Northern Hemisphere, sporadic cases of influenza occur during the summer, yet summertime outbreaks are rare. From 12 August through 2 September 1993, three influenza outbreaks in Louisiana were investigated using medical-record review, interviews, viral cultures, serology, and active surveillance for influenza-like illness in Louisiana. Attack rates in the outbreaks were 61% (69/114), 42% (24/57), and 45% (23/51). Viruses isolated were most closely related to influenza A/Beijing/32/92 (H3N2). The identification of influenza A as the cause of the first two outbreaks led to the recommendation for amantadine use in the third outbreak. Active surveillance did not detect any other outbreaks of influenza-like illness during August or September 1993. Out-of-season influenza A outbreaks can therefore occur when little influenza-like illness is present in a community. Evaluation of outbreaks of acute, febrile respiratory illness outside the influenza season should include this possibility, since rapid detection can lead to the timely use of amantadine or rimantadine.

An outbreak of influenza A/Taiwan/1/86 (H1N1) infections at a naval base and its association with airplane travel.

In late October 1986, an outbreak of influenza-like illness was detected at the Naval Air Station in Key West, Florida. Between October 10 and November 7, 1986, 60 active duty personnel reported experiencing a respiratory illness characterized by fever, cough, sore throat, and myalgia. Influenza A/Taiwan/1/86 (H1N1) virus was recovered from three symptomatic patients. Forty-one (68%) of 60 case-patients belonged to a 114-person squadron that had traveled to Puerto Rico for a temporary assignment from October 17-28, 1986. Among squadron members, the attack rate for persons previously vaccinated with the 1986-1987 trivalent influenza vaccine and for those unvaccinated was the same (37%). Transmission of infection among squadron personnel appeared to have commenced in Key West and continued in a barracks in Puerto Rico and aboard two DC-9 aircraft that transported the squadron back to Key West on October 28. There was no evidence that the outbreak spread to the surrounding civilian communities in Puerto Rico or Key West. This was the first reported outbreak of respiratory illness due to influenza A/Taiwan/1/86 (H1N1) in the continental United States in the 1986-1987 influenza season.

Outbreak of Influenza-Like Illness in a Tour Group—Alaska

Outbreak of Influenza-Like Illness in a Tour Group—Alaska

Leads from the MMWR. Outbreak of influenza-like illness in a tour group--Alaska

Leads from the MMWR. Outbreak of influenza-like illness in a tour group--Alaska

Type A influenza (H2N2) viruses isolated in Leningrad in 1980.

In April-May 1980, two independent outbreaks of influenza-like illness occurred in Leningrad among children's-home children aged from 3 months to 2 years (of 68 children under observation, 50 became ill) and among boarding-school pupils aged 15-17 years (of 50 pupils under observation, 13 became ill). A total of five influenza A virus strains were derived from one clinically healthy and three affected children of the children's home. Similar viruses were obtained from one affected boarding-school pupil and from an infected woman aged 24 years (a sporadic case within a household). On the basis of laboratory findings, all these seven strains were identified as influenza A H2N2 subtype strains. Six of the affected children showed significant seroconversion only to H2 haemagglutinin from February to May 1980. Type A influenza H2N2 virus was isolated from three persons, including the sporadic case, who also showed significant seroconversion to H2 haemagglutinin. H2N2 influenza A virus was isolated on two occasions, at a 7-day interval, from the girl N. Ju. Laboratory findings obtained from the study of the viruses isolated using up-to-date immunological and molecular-biochemical techniques enable us to conclude the following. The A/Leningrad/80 isolates belong to H2N2 sero-subtype. The viruses isolated are similar but not identical to the A/Singapore/I/57 reference strain in details of polypeptide and gene composition.

Efficacy of Influenza Vaccine in Nursing Homes

From December 10, 1982, to March 4, 1983, when influenza A (H3N2) viruses circulated in Michigan, outbreaks of influenza-like illness were identified in seven nursing homes in Genesee County; 272 (27%) of 1,018 residents were affected. Unvaccinated residents were more likely than vaccinated residents to become ill (risk ratio [RR], 2.6; 95% confidence interval [Cl], 1.8-3.6) and were subsequently more likely to be hospitalized (RR, 2.4; 95% Cl, 1.2-4.8), develop roentgenographically proven pneumonia (RR, 2.9; 95% Cl, 1.6-5.3), or die (RR, 5.6; 95% Cl, 1.2-9.1). Similar observations were made during investigations in six of the eight remaining nursing homes in Genesee County, in which 57 (12%) of 458 residents became ill sporadically. These findings suggest that influenza vaccine can reduce the incidence and severity of influenza virus infections among the elderly and chronically ill and underscore the importance of vaccination programs for those in nursing homes and in the general community.

Nosocomial influenza B virus infection in the elderly.

A hospital-acquired outbreak of influenza-like illness that involved 29 patients during 4 weeks was detected in March 1980. The average age of the patients was 63 years. Eighteen of the 29 patients with symptoms had influenza B virus infection documented by virus isolations, fourfold or greater hemagglutination inhibition antibody increases, or both. The attack rate among all hospitalized inpatients was 20%. Absenteeism of the hospital staff because of influenza-like illnesses preceded the outbreak by several weeks, suggesting staff-to-patient transmission. The patients' sera during acute illness had low hemagglutination inhibition antibody titers (geometric mean titer of 1:21) against contemporary influenza B virus antigens, indicating that the patients were highly susceptible to influenza B virus. Only one patient had received trivalent influenza vaccine during the preceding year. The excess hospital cost resulting from the outbreak was +13 270 or +458 per patient. Our observations show that the elderly are at risk of developing nosocomial influenza B virus infection and that these illnesses are costly. Continued efforts to develop efficient influenza immunization programs for elderly persons and hospital staff are worthwhile.

Outbreak of influenza A/USSR/77 at Marquette University.

An outbreak of influenzalike illness occurred at Marquette University, Milwaukee, Wisconsin, in February 1978. Epidemiologic and laboratory data indicate that the outbreak was due to influenza A/USSR/77 (N1H1) virus. A self-administered questionnaire inquiring about the presence and spectrum of illness was given to faculty members, dental students, and residents of an undergraduate dormitory. Age-specific attack rates were 61.5% for persons less than or equal to 22 years of age, 24.7% for those 23 or 24 years of age, and 9.7% for those greater than or equal to 25 years of age. This pattern of age-specific attack rates paralleled the age distribution of persons without hemagglutination-inhibiting antibody to influenza A/USSR/77 virus found in independent serosurveys. Prior swine influenza (H1N1) immunization provided no protection from illness in this outbreak. Past epidemic antibody titers in undergraduates were only weakly associated with clinical illness. The data on disease impact gathered in this study indicate that in a university setting influenza A/USSR/77 virus produced a short-lived outbreak of respiratory illness with a very high attack rate in young adults.

Laboratory-based surveillance of influenza virus in the United States during the winter of 1977--1978. II. Isolation of a mixture of A/Victoria- and A/USSR-like viruses from a single person during an epidemic in Wyoming, USA, January 1978.

At a time when outbreaks and sporadic cases of influenza caused a A/Victoria/3/75-like and A/Texas/1/77-like H3N2 strain of influenza were occurring in the Rocky Mountain region of the USA, about 60% of the students of a high school in Cheyenne, Wyoming, were involved in an outbreak of influenza-like illness. Six influenza A(H1N1) virus isolates were obtained from throat swabs collected from 12 of these students. Virus isolated from a seventh student, however, contained a mixture of H1 and H3 (A/Victoria/3/75-like) hemagglutinins and N1 and N2 neuraminidases, as shown by the ability to clone from the mixture viruses with antigenic components H1N1, H3N1, and H3N2. An antigenic hybrid virus with H3N1 composition was re-isolated from the original throat swab. The results show that one student was shedding a mixture of A/Victoria/3/75(H3N2)-like and A/USSR/90/77(H1N1)-like viruses at the time his throat swab was taken.