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Singing in Unison Without Musical Score
341
RESPIRATORY VIRAL INFECTIONS
takes no account of the total period of observation of each subject. Consequently, for a better assessment of the coexistence of exacerbation and viral infection in the same subject over the same observation period, we separated our population into groups that had or had not presented exacerbations during given periods: seven months for influenza A and B and four months for parainfluenza. Since the period of observation for the control group was equal to, or longer than, that for the exacerbation group, the likelihood of detecting a viral infection in the control group is the same as or greater than for the exacerbation group. On this basis the association between influenza and exacerbations was not clearcut, but it was higher during exacerbations (9/35, or 95.7 percent) than during quiescence (2/19, or 10.5 percent). The association of infections with parainfluenza and exacerbation seems considerable, on the contrary, being 7/24 during exacerbation (29.2 percent) and 1/38 outside (2.6 percent). The virus present during an exacerbation may possibly be the cause of it, but it is conceivable that exacerbations, set up by other factors, create cell
conditions favorable to endogenous or exogenous virus replication. REFERENCES
1 Stark JE, Heath RB, Curwen MP: Infection with parainfluenza viruses in chronic bronchitis. Thorax 20: 124, 1965 2 Stenhouse AC: Rhinovirus infection in acute exacerbations of chronic bronchitis: a controlled prospective study. Br Med J 3:461, 1967 3 Ross CA, McMichael S, Eadie MB, et al: Infective agents and chronic bronchitis. Thorax 21 :461, 1966 4 Eadie MB, Stott EJ, Grist NR: Virological studies in chronic bronchitis. Br Med J 2:671,1966 5 Sommerville RG: Respiratory syncytial virus in acute exacerbations of chronic bronchitis. Lancet 2:1247, 1963 6 Carilli AD, Gohd RD, Gordon W: A virology study of chronic bronchitis. New Engl J Med 270:123,1964 7 McNamara MJ, Phillips lA, Williams OB: Viral and Mycoplasma pneumoniae infections in exacerbations of chronic lung disease. Am Rev Resp Dis 100: 19, 1969 8 Lennette HE, Schmidt NJS: Diagnostic procedures for viral and rickettsial disease. Am J Public Health 457,1963 9 Burnet FM, Stones JD: Receptor destroying enzyme of the (Vibrio) cholerae. Aust J Exp Biol Med Sci 25:227, 1947 10 Cohen A: Textbook of Medical Virology. Oxford & Edinburgh, Blackwell Scientific Publications, 1969, p 151 11 Utz JP: Viruria in man. Progr Med ViroI6:71, 1964
Singing in Unison Without Musical Score The prize for the longest life cycle known in the insect world must be awarded to the seventeen-year cicada. The rather common cicada which often gives a concert from trees during the day and early evening is familiar to many people. Their life cycle is completed in from two to five years. The immature stages of cicadas are passed within the ground. Those of the seventeen-year species stay in the ground for seventeen years. At last the big moment arrives and out of the soil pop droves of insects. Superficially they do not resemble adult cicadas. They
CHEST, VOL. 63, NO.3, MARCH, 1973
are about an inch long. These nymphs, as they are called, must now transform into adults. Their outer shell splits down the back. Gradually the adult insect works its way out over a period of several days and the adults may live for two or three weeks. Unlike the human species, only male cicadas can "sing", but while they are alive, a concentration of insects is likely to make life miserable for people. Breland, OP: Animal Friends and Foes, New York, Harper & Brothers, 1957
RESPIRATORY VIRAL INFECTIONS
takes no account of the total period of observation of each subject. Consequently, for a better assessment of the coexistence of exacerbation and viral infection in the same subject over the same observation period, we separated our population into groups that had or had not presented exacerbations during given periods: seven months for influenza A and B and four months for parainfluenza. Since the period of observation for the control group was equal to, or longer than, that for the exacerbation group, the likelihood of detecting a viral infection in the control group is the same as or greater than for the exacerbation group. On this basis the association between influenza and exacerbations was not clearcut, but it was higher during exacerbations (9/35, or 95.7 percent) than during quiescence (2/19, or 10.5 percent). The association of infections with parainfluenza and exacerbation seems considerable, on the contrary, being 7/24 during exacerbation (29.2 percent) and 1/38 outside (2.6 percent). The virus present during an exacerbation may possibly be the cause of it, but it is conceivable that exacerbations, set up by other factors, create cell
conditions favorable to endogenous or exogenous virus replication. REFERENCES
1 Stark JE, Heath RB, Curwen MP: Infection with parainfluenza viruses in chronic bronchitis. Thorax 20: 124, 1965 2 Stenhouse AC: Rhinovirus infection in acute exacerbations of chronic bronchitis: a controlled prospective study. Br Med J 3:461, 1967 3 Ross CA, McMichael S, Eadie MB, et al: Infective agents and chronic bronchitis. Thorax 21 :461, 1966 4 Eadie MB, Stott EJ, Grist NR: Virological studies in chronic bronchitis. Br Med J 2:671,1966 5 Sommerville RG: Respiratory syncytial virus in acute exacerbations of chronic bronchitis. Lancet 2:1247, 1963 6 Carilli AD, Gohd RD, Gordon W: A virology study of chronic bronchitis. New Engl J Med 270:123,1964 7 McNamara MJ, Phillips lA, Williams OB: Viral and Mycoplasma pneumoniae infections in exacerbations of chronic lung disease. Am Rev Resp Dis 100: 19, 1969 8 Lennette HE, Schmidt NJS: Diagnostic procedures for viral and rickettsial disease. Am J Public Health 457,1963 9 Burnet FM, Stones JD: Receptor destroying enzyme of the (Vibrio) cholerae. Aust J Exp Biol Med Sci 25:227, 1947 10 Cohen A: Textbook of Medical Virology. Oxford & Edinburgh, Blackwell Scientific Publications, 1969, p 151 11 Utz JP: Viruria in man. Progr Med ViroI6:71, 1964
Singing in Unison Without Musical Score The prize for the longest life cycle known in the insect world must be awarded to the seventeen-year cicada. The rather common cicada which often gives a concert from trees during the day and early evening is familiar to many people. Their life cycle is completed in from two to five years. The immature stages of cicadas are passed within the ground. Those of the seventeen-year species stay in the ground for seventeen years. At last the big moment arrives and out of the soil pop droves of insects. Superficially they do not resemble adult cicadas. They
CHEST, VOL. 63, NO.3, MARCH, 1973
are about an inch long. These nymphs, as they are called, must now transform into adults. Their outer shell splits down the back. Gradually the adult insect works its way out over a period of several days and the adults may live for two or three weeks. Unlike the human species, only male cicadas can "sing", but while they are alive, a concentration of insects is likely to make life miserable for people. Breland, OP: Animal Friends and Foes, New York, Harper & Brothers, 1957