Respiratory virus infections during the winter at the South Pole
Medical studies Respiratory virus infections during the winter at the South Pole HAROLD C. MUCHMORE, ALAN J. PARKINSON, and E. NAN SCOTT Oklahoma Medical Research Foundation Departments of Medicine, Microbiology and Immunology
and
The Veterans Administration Medical Center University of Oklahoma Health Sciences Center Oklahoma City, Oklahoma 73104
Outbreaks of common colds have been noted among personnel at many isolated antarctic stations immediately following the end of the isolation period and resumption of contact with the outside world (Allen 1973; Muchmore and Shurley 1974; Parkinson, Muchmore, and Scott 1979a). The etiologic agents responsible for these end-of-isolation outbreaks at South Pole and McMurdo Stations have been identified. Viruses recovered have included rhinovirus, parain flue nzavirus types 1 and 3 (Parkinson et al. 1979a) and adenovirus (Dick et al. 1978). The introduction of these agents to an isolated, susceptible community and the resulting outbreak of infection support current concepts of common-cold epidemiology. However, apparently contrary to these concepts are reports of occurrences of common colds during the middle of the isolation period, long after the accepted incubation period for human common cold viruses and when the introduction of new virus to the community was impossible (Allen 1973; Allen et al. 1973). We have recorded occurrences of mid-isolation common colds among the 18-20 subjects wintering at South Pole Station each year since our observations began in 1974 (table). These outbreaks often begin 7-18 and 22-27 weeks after the beginning of the winter isolation period. Symptoms are typically mild to moderate and include coryza, malaise, sore throat, headache, and nasal congestion. The symptoms last for 4 to 7 days and often appear to spread to one or more additional subjects within 7 days. The occurrence of these infections poses several interesting problems concerning their etiology and the source of virus within this closed community. During the 1974 winter, colds occurred in two apparently related clusters, one beginning on 2 April and a second on 7 September. Two subjects gave histories of opening boxes of electrical components and clothing. Howeyer, opening boxes of supplies is a recurring event for all personnel throughout the year. Eleven acute throat swabs were collected from this winter group, stored at - 20°C, and transported to the University of 1983 REVIEW
Otago in Dunedin, New Zealand for processing; no virus was isolated. In 1975 a major outbreak of colds began on 14 June, two days after a meeting of the 300 club. This time 101 throat swabs were collected throughout the winter period and returned to New Zealand for processing, but again no virus was grown. During winter 1976, episodes of respiratory tract illness occurred in May and August. Again no virus was grown from the specimens taken during these outbreaks. However, parainfluenzavirus types 1 and 3 had been recovered from both winter and summer support personnel at McMurdo and South Pole Stations the preceding austral summer (October-December 1975). Hemagglutination inhibition assays on multiple sera collected from the 1976 winter group showed changes in antibody titers to parainfluenzavirus types 1 and 3 corresponding to the episodes of infection (Parkinson, Muchmore, and Scott 1979b). These results suggest that parainfluenzaviruses were responsible for the mid-isolation colds that occurred during the 1976 winter isolation period. In contrast, however, few changes in parainfluenzavirus antibody titers were detectable in the 1977 wintering subjects. Colds occurred after 10 and 22 weeks of complete social isolation during the winter of 1978. Parairtfluenzaviruses types 1 and 3 were recovered from both symptomatic and asymptomatic subjects by direct inoculation of throat-swab specimens into cell cultures maintained throughout the winter at South Pole Station by a wintering scientist (Joe E. Humphries). Fourfold changes in antibody titers were also detected in both symptomatic and asymptomatic subjects during these epi-
Mid-Isolation upper respiratory infections (uRI) South Pole Station, Antarctica URI Station Station URI Year closing episode 1 episode 2 opening
1974 17 Feb. 2 Apr. (7) a 7 Sept. (6) 2 Nov. 1975 13 Feb. 14 June (7) 12 July (3) 25 Oct. 1976 13 Feb. 2 May (4) 5 Aug. (4) 30 Oct. 1977 13 Feb. 9 May (3) None 3 Nov. 1978 9 Feb. 4 Apr. (8) 22 Aug. (1) 1 Nov. 1979 12 Feb. 5 Apr. (4) 5 Aug. (2) 2 Nov. 1980 10 Feb. 10 Apr. (2) 1 Sept. (2) 5 Nov. 1981 9 Feb. 6 Apr. (2) 23 July (2) 5 Nov. 1982 10 Feb. 15 Jun. (5) 10 Aug. (3) 6 Nov. a Numbers in parentheses are the number of winter-over individuals with symptoms. Each winter-over group consists of 18-20 individuals.
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sodes indicating the presence of parainfluenzaviruses within this community during isolation (Muchmore et al. 1979). During the 1981 winter, colds occurred from 6 to 12 April and again from 23 to 29 July. Of the eight acute throat-swab specimens collected, stored frozen during the winter, and inocu lated into cell culture at South Pole Station during the following summer, one rhinovirus type 28 was recovered from a specimen collected on 29 July 1981. The source of a rhinovirus obtained from this asymptomatic subject, who had been socially isolated for 24 weeks, is unknown. However, a midwinter airdrop into South Pole Station took place on 22 June 1981. Although the persistence of rhinovirus in the environment at South Pole Station for 32 days is unlikely, this possibility cannot be excluded. During the 1982 winter, colds were again present but were accompanied by acute gastrointestinal symptoms beginning on 18 June. This outbreak began 7 days prior to the United States Air Force midwinter air drop for 1982. No virus or bacterial pathogens were isolated from frozen acute specimens collected during this year. Serologic assays and studies for the presence of noncultivable viruses are still in progress. The presence of human respiratory and enteric viruses in this community after more than 10 weeks of total isolation suggests the long-term persistence of these viruses either in the environment or in one or more subjects isolated at the South Pole. We have shown previously that pa rain flue nzaviruses do not survive on surfaces for 10 weeks in the south polar environment, and that the environment did not provide the source of parainfluenzavirus related colds observed during the 1978 winter (Parkinson et al. 1982). The absence of parainfluenzavirus serologic responses during 1977, the recovery of rhinovirus from a symptomatic subject during 1981, and the presence of nonbacterial gastroenteritis during the 1982 winter at South Pole Station suggest that more than one virus may be involved in the etiology of these midwinter common-cold episodes. The data presented demonstrate clearly that upper respiratory viral infections occur with
230
low frequency in people in isolated groups. Identification of the source of these viruses will provide an added dimension of complexity to the epidemiology of the common cold. This research has been supported by National Science Foundation grant DPP 80-20092, the Oklahoma Medical Research Foundation, and the Research Service of the Veterans Administration, Oklahoma City, Oklahoma.
References Allen, T. R. 1973. Common colds in Antarctica. Journal of Hygiene (Cambridge), 71, 649456. Allen, T. R., A. F. Bradburne, E. J. Stott, C. S. Goodwin, and D. A. J. Tyrrell. 1973. An outbreak of common colds at an Antarctic base after seventeen weeks of complete social isolation. Journal of Hygiene (Cambridge), 71, 657-667. Dick, E. C., F. Polyak, K. S. Kapitan, D. M. Warshauer, A. D. Mandel, B. S. Thomas, and J. Rankin. 1978. Respiratory virus transmission at McMurdo Station and Scott Base (New Zealand) during the winter fly-in period 1977. Antarctic Journal of the U.S., 13(4), 170-171. Muchmore, H. G., and J . J. Shurley. 1974. Microbiology and immunology of South Pole antigen deprivation. Antarctic Journal of the U. S., 9(4), 199-120. Muchmore, H. G., A. J. Parkinson, J. E. Humphries, E. N. Scott, L. V. Scott, D. A. MacIntosh, M. K. Cooney, and J. A. R. Miles. 1979. Respiratory virus shedding throughout isolation at South Pole. Antarctic Journal of the U.S., 14(5), 185-186. Parkinson, A. J., H. C. Muchmore, and L. V. Scott. 1979a. Parainfluenzavirus upper respiratory infections at McMurdo Station during the austral summer 1975-76. Antarctic Journal of the U.S., 14(5), 186-187. Parkinson, A. J., H. C. Muchmore, and L. V. Scott. 1979b. Persistent parainfluenzavirus infections at South Pole Station during the winter 1976. Antarctic Journal of the U.S., 14(5), 188-189. Parkinson, A. J., H. C. Muchmore, E. N. Scott, and L. V. Scott. 1982. Environmental survival of human respiratory viruses at South Pole station Antarctic. Antarctic Journal of the U.S., 17(5), 196-197.
ANTARCTIC JOURNAL
and
The Veterans Administration Medical Center University of Oklahoma Health Sciences Center Oklahoma City, Oklahoma 73104
Outbreaks of common colds have been noted among personnel at many isolated antarctic stations immediately following the end of the isolation period and resumption of contact with the outside world (Allen 1973; Muchmore and Shurley 1974; Parkinson, Muchmore, and Scott 1979a). The etiologic agents responsible for these end-of-isolation outbreaks at South Pole and McMurdo Stations have been identified. Viruses recovered have included rhinovirus, parain flue nzavirus types 1 and 3 (Parkinson et al. 1979a) and adenovirus (Dick et al. 1978). The introduction of these agents to an isolated, susceptible community and the resulting outbreak of infection support current concepts of common-cold epidemiology. However, apparently contrary to these concepts are reports of occurrences of common colds during the middle of the isolation period, long after the accepted incubation period for human common cold viruses and when the introduction of new virus to the community was impossible (Allen 1973; Allen et al. 1973). We have recorded occurrences of mid-isolation common colds among the 18-20 subjects wintering at South Pole Station each year since our observations began in 1974 (table). These outbreaks often begin 7-18 and 22-27 weeks after the beginning of the winter isolation period. Symptoms are typically mild to moderate and include coryza, malaise, sore throat, headache, and nasal congestion. The symptoms last for 4 to 7 days and often appear to spread to one or more additional subjects within 7 days. The occurrence of these infections poses several interesting problems concerning their etiology and the source of virus within this closed community. During the 1974 winter, colds occurred in two apparently related clusters, one beginning on 2 April and a second on 7 September. Two subjects gave histories of opening boxes of electrical components and clothing. Howeyer, opening boxes of supplies is a recurring event for all personnel throughout the year. Eleven acute throat swabs were collected from this winter group, stored at - 20°C, and transported to the University of 1983 REVIEW
Otago in Dunedin, New Zealand for processing; no virus was isolated. In 1975 a major outbreak of colds began on 14 June, two days after a meeting of the 300 club. This time 101 throat swabs were collected throughout the winter period and returned to New Zealand for processing, but again no virus was grown. During winter 1976, episodes of respiratory tract illness occurred in May and August. Again no virus was grown from the specimens taken during these outbreaks. However, parainfluenzavirus types 1 and 3 had been recovered from both winter and summer support personnel at McMurdo and South Pole Stations the preceding austral summer (October-December 1975). Hemagglutination inhibition assays on multiple sera collected from the 1976 winter group showed changes in antibody titers to parainfluenzavirus types 1 and 3 corresponding to the episodes of infection (Parkinson, Muchmore, and Scott 1979b). These results suggest that parainfluenzaviruses were responsible for the mid-isolation colds that occurred during the 1976 winter isolation period. In contrast, however, few changes in parainfluenzavirus antibody titers were detectable in the 1977 wintering subjects. Colds occurred after 10 and 22 weeks of complete social isolation during the winter of 1978. Parairtfluenzaviruses types 1 and 3 were recovered from both symptomatic and asymptomatic subjects by direct inoculation of throat-swab specimens into cell cultures maintained throughout the winter at South Pole Station by a wintering scientist (Joe E. Humphries). Fourfold changes in antibody titers were also detected in both symptomatic and asymptomatic subjects during these epi-
Mid-Isolation upper respiratory infections (uRI) South Pole Station, Antarctica URI Station Station URI Year closing episode 1 episode 2 opening
1974 17 Feb. 2 Apr. (7) a 7 Sept. (6) 2 Nov. 1975 13 Feb. 14 June (7) 12 July (3) 25 Oct. 1976 13 Feb. 2 May (4) 5 Aug. (4) 30 Oct. 1977 13 Feb. 9 May (3) None 3 Nov. 1978 9 Feb. 4 Apr. (8) 22 Aug. (1) 1 Nov. 1979 12 Feb. 5 Apr. (4) 5 Aug. (2) 2 Nov. 1980 10 Feb. 10 Apr. (2) 1 Sept. (2) 5 Nov. 1981 9 Feb. 6 Apr. (2) 23 July (2) 5 Nov. 1982 10 Feb. 15 Jun. (5) 10 Aug. (3) 6 Nov. a Numbers in parentheses are the number of winter-over individuals with symptoms. Each winter-over group consists of 18-20 individuals.
229
sodes indicating the presence of parainfluenzaviruses within this community during isolation (Muchmore et al. 1979). During the 1981 winter, colds occurred from 6 to 12 April and again from 23 to 29 July. Of the eight acute throat-swab specimens collected, stored frozen during the winter, and inocu lated into cell culture at South Pole Station during the following summer, one rhinovirus type 28 was recovered from a specimen collected on 29 July 1981. The source of a rhinovirus obtained from this asymptomatic subject, who had been socially isolated for 24 weeks, is unknown. However, a midwinter airdrop into South Pole Station took place on 22 June 1981. Although the persistence of rhinovirus in the environment at South Pole Station for 32 days is unlikely, this possibility cannot be excluded. During the 1982 winter, colds were again present but were accompanied by acute gastrointestinal symptoms beginning on 18 June. This outbreak began 7 days prior to the United States Air Force midwinter air drop for 1982. No virus or bacterial pathogens were isolated from frozen acute specimens collected during this year. Serologic assays and studies for the presence of noncultivable viruses are still in progress. The presence of human respiratory and enteric viruses in this community after more than 10 weeks of total isolation suggests the long-term persistence of these viruses either in the environment or in one or more subjects isolated at the South Pole. We have shown previously that pa rain flue nzaviruses do not survive on surfaces for 10 weeks in the south polar environment, and that the environment did not provide the source of parainfluenzavirus related colds observed during the 1978 winter (Parkinson et al. 1982). The absence of parainfluenzavirus serologic responses during 1977, the recovery of rhinovirus from a symptomatic subject during 1981, and the presence of nonbacterial gastroenteritis during the 1982 winter at South Pole Station suggest that more than one virus may be involved in the etiology of these midwinter common-cold episodes. The data presented demonstrate clearly that upper respiratory viral infections occur with
230
low frequency in people in isolated groups. Identification of the source of these viruses will provide an added dimension of complexity to the epidemiology of the common cold. This research has been supported by National Science Foundation grant DPP 80-20092, the Oklahoma Medical Research Foundation, and the Research Service of the Veterans Administration, Oklahoma City, Oklahoma.
References Allen, T. R. 1973. Common colds in Antarctica. Journal of Hygiene (Cambridge), 71, 649456. Allen, T. R., A. F. Bradburne, E. J. Stott, C. S. Goodwin, and D. A. J. Tyrrell. 1973. An outbreak of common colds at an Antarctic base after seventeen weeks of complete social isolation. Journal of Hygiene (Cambridge), 71, 657-667. Dick, E. C., F. Polyak, K. S. Kapitan, D. M. Warshauer, A. D. Mandel, B. S. Thomas, and J. Rankin. 1978. Respiratory virus transmission at McMurdo Station and Scott Base (New Zealand) during the winter fly-in period 1977. Antarctic Journal of the U.S., 13(4), 170-171. Muchmore, H. G., and J . J. Shurley. 1974. Microbiology and immunology of South Pole antigen deprivation. Antarctic Journal of the U. S., 9(4), 199-120. Muchmore, H. G., A. J. Parkinson, J. E. Humphries, E. N. Scott, L. V. Scott, D. A. MacIntosh, M. K. Cooney, and J. A. R. Miles. 1979. Respiratory virus shedding throughout isolation at South Pole. Antarctic Journal of the U.S., 14(5), 185-186. Parkinson, A. J., H. C. Muchmore, and L. V. Scott. 1979a. Parainfluenzavirus upper respiratory infections at McMurdo Station during the austral summer 1975-76. Antarctic Journal of the U.S., 14(5), 186-187. Parkinson, A. J., H. C. Muchmore, and L. V. Scott. 1979b. Persistent parainfluenzavirus infections at South Pole Station during the winter 1976. Antarctic Journal of the U.S., 14(5), 188-189. Parkinson, A. J., H. C. Muchmore, E. N. Scott, and L. V. Scott. 1982. Environmental survival of human respiratory viruses at South Pole station Antarctic. Antarctic Journal of the U.S., 17(5), 196-197.
ANTARCTIC JOURNAL
