Virus survival on inanimate surfaces' M. C. MAHLAND C. SADLER
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Mic~.obiologySecriotl, Corpornre re sear el^, S . C . Johtzsotz & Sotr, Itlc., Rocitze, Wiscot~sit~ 53403 Accepted January 22, 1975 MAHL,M. C., and C. SADLER. 1975. Virus survival on inanimate surfaces. Can. J . Microbiol. 21: 8 19-823. The persistence of several types of viruses on hard, inanimate surfaces under different relative humidities, temperatures, and types of surfaces was investigated. No differences in survival on glass, vinyl asbestos tile, ceramic tile, and stainless steel were found. Under conditions of low humidity and room temperature, adenovirus, poliovirus, and herpes simplex virus survived for at least 8 weeks. Vaccinia and coxsackie viruses survived for at least 2 weeks but differences due to humidity and temperature were not detected. The long-term survival of viruses on common surfaces found in many environments, in addition to the laboratory, emphasizes the possible role of hard surfaces in the transmission of viruses. MAHL,M. C., et C. SADLER. 1975. Virus survival on inanimate surfaces. Can. J . Microbiol. 21: 8 19-823. La persistance de quelques types de virus sur des surfaces inertes solides a CtC Ctudiee dans diverses conditions d'humidite relative et de temperature et pour divers types de surfaces. La survie est la m6me sur le verre, surune tuile vinylique d'amiante, sur une tuile de ceramique et sur I'acier inoxydable. A faible humidit6 et B la temperature ambiante, les adenovirus, poliovirus et le virus de I'herpes simplex survivent au moins 8 semaines. Les virus coxsackies et de la vaccine survivent au moins 2 semaines, mais les differences entre I'humiditt et la temperature n'ont pas ete detectees. La longue survie de virus sur des surfaces qui se rencontrent communCment dans plusieurs endroits, en plus du laboratoire, accentue le r6le possible des surfaces solides dans la transmission de virus. [Traduit par le journal]
Introduction The survival of viruses in the dried state on inanimate surfaces has received scattered attention in the literature. Edward (3) showed that the PR-8 strain of influenza virus persisted on dust, cotton sheets, and glass slides for several weeks at 22°C; survival was less at 37°C. Parker and MacNeal (8) also showed the survival of dried influenza viruses on the skin and glass slides; however, study times were no longer than 200 min. Herpes simplex and vaccinia viruses were found by Kibrick (5) to persist in floor sweepings for a t least 2 weeks after patients with generalized eruptions had vacated the room. Kingston (6) reported 1% recovery of respiratory syncytial virus which was dried on polythene surfaces for 24 h. Buckland and Tyrrell (1) published data showing reduction of titer of many viruses during drying on glass slides; however, n o experiments were conducted longer than 24 h. It was our purpose in this study to determine how long certain viruses would persist on hard, 'Received October 8, 1974.
inanimate surfaces common in the laboratory environment, under conditions of ambient humidities and temperatures.
Materials and Methods Viruses Poliovirus type 2 (MEF-1 strain) and vaccinia virus (Lederle strain) were obtained from R. W. Sidwell, Southern Research Institute, Birmingham, Alabama. Adenovirus type 2 was received from E. C. Dick and coxsackie B3 was obtained from D. Nelson, both from the State Laboratory of Hygiene, Madison, Wisconsin. The herpes simplex virus type 1 (macroplaque strain) was obtained from J. Blackwell, Environmental Protection Agency, Beltsville, Maryland. Cell Culture and Media The human heteroploid continuous cell lines HEp-2 and HeLa originally supplied by E. C. Dick were used throughout these studies. Cell cultures were grown in Eagle's minimum essential medium (MEM) (Difco Laboratories, Detroit, Michigan) plus 10% heat-inactivated fetal calf serum (CS) (Reheis Chemical Co., Chicago, Illinois) in 75-cmZ growth area Falcon cellculture flasks. Preparation of Virus Suspensions All suspensions of the above viruses were propagated in cell monolayers which had been washed twice with Hanks' balanced salts solution (BSS) and resupplied with M E M plus 2% CS. Two millilitres of virus inoculum
820
C A N . J. MICROBIOL. VOL. 21, 1975
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was then added to the flask and incubation was at 37°C until complete destruction of the monolayer occurred. The flask contents were frozen and thawed twice, and cell debris was removed by centrifugation at 350 x g for I0 min. The supernatant fluids were placed in vials and stored at - 70°C until used in experiments. Hu~nirlityClra~?rbers Plastic boxes measuring 12 cm x 17.1 cm x 6 cm (Tri-State Plastic Molding Co., Henderson, Kentucky) were half-filled with saturated solutions of glucose, K H 2 P 0 4 , or NaOH to obtain relative humidities of 55%, 93-96%, and 3-7%, respectively (10). Metal test tube racks of appropriate size were placed in the boxes so that the top of the rack was 3 cm above the surface of the liquid. Chambers were incubated at 25'C and at 37°C and humidity was checked weekly with a dewpoint apparatus. Procer11rrrr.e for S~rruiualTests A virus suspension was removed from the -70°C freezer and melted, and 0.2-ml amounts were pipetted onto 2.5-cmZ glass nlicroscope slides contained in the humidity chanlbers. The slides in the low and medium humidity chambers dried within 30 min; slides in the high humidity chamber remained partially wet during
the entire test. In a preliminary trial, half of the chambers were placed 60 cm under one 100-W incandescent light bulb during the entire test period, and the other half were kept in complete darkness. Although light appeared to be a factor as shown in Table 1, it was eliminated from the remainder of the study because of our inability to adequately measure and monitor intensity. Therefore, in all subsequent experiments, the humidity chambers were stored in darkness and exposed to light only when slides were removed. At desired intervals, one slide from each chamber was removed and placed into a 32- x 200-mm test tube containing 20 ml of MEM plils 2 Z CS and shaken vigorously. The suspension was designated the lo-' dilution of the original virus suspension. Subsequent dilutions were made in MEM plus 2% CS and 1-ml quantities were transferred directly into cell-culture test tubes when tube assays were performed. Dilutions including the initial collection of virus were made with Hanks' BSS when a plaque assay was being performed. Assay Procecllrre Adenovirus, coxsackie, and vaccinia viruses were assayed by tube techniques using 10-fold dilutions, with four replicate cell-culture tubes at each dilution. Virus titer, as cell culture 50% infective dose (CCID,,/rnl), based on cytopathic effect (CPE) observed, was deter-
TABLE 1 Adenovirus-2 survival on various surfaces under varying light and relative humidity conditions at 37°C CCID5,/slide4 93% RH Time
Tileh
LightC
Dark
Ih
A B C D
106.0 105.75 106.0 106.0
106.5 106.0 106.0 105.75
1 week
A B C D
NVDd NVD NVD NVD
3 weeks
A B C D
NVD NVD NVD NVD
104.75 105.5 104.~ 104.~ 102.25 102.75 101.75 101.75
6 weeks
A B C D
NVD NVD NVD NVD
8 weeks
A B C D
NVD NVD NVD NVD
7% Mi Light
Dark
.Initial concentration o f 1 0 6 . 7 5 CCIDSo/slide. bA = glass. B = vinyl asbestos floor tile. C = ceramic tile. D = stainless steel. Cone 100-W incandescent light bulb 60 cm above the chambers. dNo virus detected. sensitivity o f assay was 101.5 CCIDSo.
821
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M A H L A N D SADLER: V I R U S S U R V I V A L
tests were performed using glass slides. The experimental design was expanded to include two temperatures (25°C and 37°C) and three humidities, 93%, 55%, and 7%. Five viruses were studied under these conditions and the results are shown in Tables 2-6. Adenovirus-2 survival was followed for 12 weeks and virus recovery was found possible under conditions of low humidity (Table 2). Herpes simplex virus and poliovirus-2 survived for at least 8 weeks under low humidity conditions (Tables 3 and 4). Vaccinia and coxsackievirus B3 survived for a shorter time, 3 to 4 weeks, and the influence of humidity was not observed (Tables 5 and 6).
mined by the Karber technique (7). Herpes and poliovirus were assayed by plaquing techniques whereby 1 ml of the dilution was pipetted onto cell-culture monolayers grown in Falcon 35-mm plastic plates. After a 2-h absorption period, the liquid was decanted and replaced with 2 ml of MEM plus 1% CS plus 0.2% gamma globulin (Cutter Laboratories, Berkeley, California). At the end of 5 days of incubation in a 5% C 0 2 atmosphere at 37"C, the medium was removed, cell sheets were fixed with methyl alcohol and stained with Giemsa stain, and plaques were counted.
Results Adenovirus-2 was studied in a preliminary test to determine the effects of the type of environmental surface on survival of the virus. Vinyl floor tile, ceramic tile, stainless steel, and glass microscope slides were cut into 2.5-cm squares and sterilized by autoclaving. Results are summarized in Table 1. Viable adenovirus-2 persisted on the slides for at least 8 weeks when held at low humidity (Table I), but remained on the slides less than 1 week in the dark at high humidity. Type of surface was not shown to be critical and further
Discussion The above data confirm and extend the findings of others that viruses can indeed persist weeks and even months on inanimate surfaces under ambient conditions of temperature and humidity. The types of common surfaces which
TABLE 2 Survival of adenovirus-2 on glass slides at three relative humidities and two temperatures CCIDSo/slidea Condition
4h
1 day
1 week
2 weeks
4 weeks
8 weeks
12 weeks
25°C
96x RH 55% R H 7% RH
107.5 107.5 107.5
108.25 108.0 107.5
106.75 107.75 106.25
106.0 lo5 107.~
107.~ 107.25 107.25
102.75 104.75 105.25
NVDb NVD 104.75
37°C
93% R H 55% R H 3y0RH
108.0 108.75 107.5
107.75 106.75 107.25
107.~ 106.0 107.25
107.0 106.75 106.75
102.5 104.5 106.25
103.75 l ~ 105.5
~
NVD . ~ NVD 104.75
Olnitial slides recerved 108.0CCIDSo. bNo virus detected (less than 10' 5 CCIDSo).
TABLE 3 Herpes simplex virus survival on glass slides at three relative humidities and two temperatures Plaque-forming units (PFU)/slidea
25°C
37°C
Condition
4h
1 day
1 week
2 weeks
6 weeks
8 weeks
96% R H 55% R H 7% R H 93% R H 55% R H 3% R H
1 . 5 105 ~ 9 . 9 lo4 ~ 1.5x103 8.1 x104 8 . 9 lo4 ~ 2 . 1 x103
4 . 5 lo3 ~ 4 . 5 lo3 ~ 1 . 2 lo2 ~ NVD NVD 5 . 2 10' ~
NVDb NVD 2 . 0 lo3 ~ NVD NVD 1 . 3 lo3 ~
NVD NVD 3.9x103 2.3 x lo3
6 . 2 10' ~ 1.8x102
9.2 x 10' -
'1Initlal sltdes received 3.7 x 105 PFU. bNo virus detected at the lowest detection limit of 100 PFU.
-
1 . 3 l~o 3
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CAN. J . MICROBIOL. VOL. 21, 1975
TABLE 4 Poliovirus-2 survival on glass slides at three relative humidities and two temperatures
Condition
4h
1 day
1 week
2 weeks
4 weeks
6 weeks
8 weeks
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--
9 6 % ~ 8~ . 0 ~ 1 0 ~ 1 . 2 ~ 1 0 ~ 4 . 1 ~ 1 0 ~ 6 . 0 ~ 1 0 ~ 1 . 0 ~ 1 0 ~ N V D ~ 55zRH 1.2x108 8.7x107 6.6x105 7.4x103 NVD NVD 7%RH 1.6x106 1.1x106 7.5x105 3.2x105 2.9x104 7 . 0 104 ~
25°C
37"~
9 3 % ~ ~1 . 0 ~ 1 0 ~ 4 . 6 ~ 1 0 ~ NVD 55% RH 8 . 0 lo7 ~ 8 . 0 lo6 ~ NVD 3ZRH 5.0x105 1.0x105 8.6x103
nlnitial slides received 1.2 x 10BPFU. bNo virus detected at the lowest detection limit of
NVD NVD 1.1x103
-
-
-
1.7x103
3.1x103
NVD -
2.0x102
2.1x103
PFU.
TABLE 5 Vaccinia virus survival on glass slides at three relative humidities and two temperatures
25°C
37°C
Condition
4h
1 day
1 week
2 weeks
3 weeks
4 weeks
5 weeks
96% RH 55% RH 7% RH 93% RH 55% RH 3% RH
106.5 106.0 106.0 105.75 106.5 106.0
106.5 106.5 106.25
106.5 105.75 105.75
1O5.O 104.0 105.5
104.~ 102.5 103.5
104.~ 102.0 103.5
102.5 NVDb 102.0
103.75 103.75 103.5
102.5 103.25 103.25
103.~ i ~ ~ 103.25
io3.0 1.0 3 .~~ 102.75
102.5 102.0 102.0
NVD NVD NVD
olnitial slides received CCID,,. CCID50). bNo virus detected (less than
TABLE 6 Coxsackie virus B3 survival on glass slides at three relative humidities and two temperatures
25°C
37°C
Condition
4h
1 day
1 week
2 weeks
96% RH 55% RH 7% RH 93% R H 55% R H 3% RH
106.25 106.5 104.75
105.25 105.25
10 4 . ~ 105.0 102.25
l ~ 102.25 102.5
103.25 103.~ 102.0
102.0 102.0 102.0
105.75 106.0 104.~
104.5 104.O 105.25 103.~
3 weeks ~
. NVD ~ NVD NVD NVD NVD NVD
'Initial slides received 106.25CCID,,. virus detected (less than 10'~3CCC130).
were tested did not have an effect on adenovirus survival. Survival of vaccinia and poliovirus on fabrics has been extensively studied by Sidwell and Dixon (2, 9), who found these viruses t o persist for many weeks in the dark on various types of fabrics (e.g. wool and cotton). They also found that the viruses survived better a t 35%
relative humidity (RH) than a t 78% R H a t 25°C. Hendley et al. (4) showed that volunteers could be infected by rhinovirus on fingertips rubbed over surfaces upon which virus had been dried. The public health significance of the survival of viruses on surfaces has not been fully explored.
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MAHL AND SADLER: VIRUS SURVIVAL
The work reported in this study shows that viruses can survive for weeks O n surfaces under temperature and humidity. Because viruses can remain viable and thus potentially infectious for long times, inanimate surfaces should be considered as a factor in virus transmission. 1. BUCKLAND,F. E.,andD. A. J. TYRRELL. 1962. Lossof infectivity on drying various viruses. Nature (Lond.), 195: 1063-1064. 2. DIXON. G. J., R . W. SlDwELL,and E. MCNEIL.1966. Quant~tat~ve studies on fabrics as disseminators of vlruses. 11. Persistence of poliomyelitis virus on cotton and wool fabrics. Appl. Microbiol. 14: 183-188. 3. E D W A R DD., G. 1941. Resistance of influenza virus to drying and ~ t sdemonstration on dust. Lancet, 241: 664-666. 4. HEWDLEY,J . O., R. P. WENZEL, and J. M. GWALTNEY, JR. 1973. Transmission of rhinovirus
5, 6. 7.
8. 9.
10.
823
colds by self-inoculation. New Engl. J. Med. 288: 1361-1364. KIBRICK, S . 1959, The persistence of virus in the environment of patients with Kaposi's varicelliform eruption. J. Dis. Child. 98: 609-61 I . KINGSTON, D. 1968. Towards the isolation of respiratory syncytial virus from the environment. .I. ~ p p l . Bacte~.iol.31: 498-5 10. LENNETTE,E . H., and N. J. SCHMIDT. (Edito~.~.) 1964. Diagnostic procedures for viral and rickettsia1 diseases. %d ed. American Public Health Association. pp. 47-50. PARKER, E. R., and W. J. MACNEAL.1944. Persistence of influenza virus on the human hand. J. Lab. Clin. Med. 29: 121-126. S I D W E L LR., W., G. J . DIXON, and E. MCNEIL.1966. Quantitative studies on fabrics as disseminators of viruses. 1. Persistence of vaccinia virus on cotton and wool fabrics. Appl. Microbiol. 14: 55-59. WINSTON, P. W., and D. H. BATES.1960. Saturated solutions for the control of humidity in biological research. Ecology, 41: 232-237.
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Mic~.obiologySecriotl, Corpornre re sear el^, S . C . Johtzsotz & Sotr, Itlc., Rocitze, Wiscot~sit~ 53403 Accepted January 22, 1975 MAHL,M. C., and C. SADLER. 1975. Virus survival on inanimate surfaces. Can. J . Microbiol. 21: 8 19-823. The persistence of several types of viruses on hard, inanimate surfaces under different relative humidities, temperatures, and types of surfaces was investigated. No differences in survival on glass, vinyl asbestos tile, ceramic tile, and stainless steel were found. Under conditions of low humidity and room temperature, adenovirus, poliovirus, and herpes simplex virus survived for at least 8 weeks. Vaccinia and coxsackie viruses survived for at least 2 weeks but differences due to humidity and temperature were not detected. The long-term survival of viruses on common surfaces found in many environments, in addition to the laboratory, emphasizes the possible role of hard surfaces in the transmission of viruses. MAHL,M. C., et C. SADLER. 1975. Virus survival on inanimate surfaces. Can. J . Microbiol. 21: 8 19-823. La persistance de quelques types de virus sur des surfaces inertes solides a CtC Ctudiee dans diverses conditions d'humidite relative et de temperature et pour divers types de surfaces. La survie est la m6me sur le verre, surune tuile vinylique d'amiante, sur une tuile de ceramique et sur I'acier inoxydable. A faible humidit6 et B la temperature ambiante, les adenovirus, poliovirus et le virus de I'herpes simplex survivent au moins 8 semaines. Les virus coxsackies et de la vaccine survivent au moins 2 semaines, mais les differences entre I'humiditt et la temperature n'ont pas ete detectees. La longue survie de virus sur des surfaces qui se rencontrent communCment dans plusieurs endroits, en plus du laboratoire, accentue le r6le possible des surfaces solides dans la transmission de virus. [Traduit par le journal]
Introduction The survival of viruses in the dried state on inanimate surfaces has received scattered attention in the literature. Edward (3) showed that the PR-8 strain of influenza virus persisted on dust, cotton sheets, and glass slides for several weeks at 22°C; survival was less at 37°C. Parker and MacNeal (8) also showed the survival of dried influenza viruses on the skin and glass slides; however, study times were no longer than 200 min. Herpes simplex and vaccinia viruses were found by Kibrick (5) to persist in floor sweepings for a t least 2 weeks after patients with generalized eruptions had vacated the room. Kingston (6) reported 1% recovery of respiratory syncytial virus which was dried on polythene surfaces for 24 h. Buckland and Tyrrell (1) published data showing reduction of titer of many viruses during drying on glass slides; however, n o experiments were conducted longer than 24 h. It was our purpose in this study to determine how long certain viruses would persist on hard, 'Received October 8, 1974.
inanimate surfaces common in the laboratory environment, under conditions of ambient humidities and temperatures.
Materials and Methods Viruses Poliovirus type 2 (MEF-1 strain) and vaccinia virus (Lederle strain) were obtained from R. W. Sidwell, Southern Research Institute, Birmingham, Alabama. Adenovirus type 2 was received from E. C. Dick and coxsackie B3 was obtained from D. Nelson, both from the State Laboratory of Hygiene, Madison, Wisconsin. The herpes simplex virus type 1 (macroplaque strain) was obtained from J. Blackwell, Environmental Protection Agency, Beltsville, Maryland. Cell Culture and Media The human heteroploid continuous cell lines HEp-2 and HeLa originally supplied by E. C. Dick were used throughout these studies. Cell cultures were grown in Eagle's minimum essential medium (MEM) (Difco Laboratories, Detroit, Michigan) plus 10% heat-inactivated fetal calf serum (CS) (Reheis Chemical Co., Chicago, Illinois) in 75-cmZ growth area Falcon cellculture flasks. Preparation of Virus Suspensions All suspensions of the above viruses were propagated in cell monolayers which had been washed twice with Hanks' balanced salts solution (BSS) and resupplied with M E M plus 2% CS. Two millilitres of virus inoculum
820
C A N . J. MICROBIOL. VOL. 21, 1975
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was then added to the flask and incubation was at 37°C until complete destruction of the monolayer occurred. The flask contents were frozen and thawed twice, and cell debris was removed by centrifugation at 350 x g for I0 min. The supernatant fluids were placed in vials and stored at - 70°C until used in experiments. Hu~nirlityClra~?rbers Plastic boxes measuring 12 cm x 17.1 cm x 6 cm (Tri-State Plastic Molding Co., Henderson, Kentucky) were half-filled with saturated solutions of glucose, K H 2 P 0 4 , or NaOH to obtain relative humidities of 55%, 93-96%, and 3-7%, respectively (10). Metal test tube racks of appropriate size were placed in the boxes so that the top of the rack was 3 cm above the surface of the liquid. Chambers were incubated at 25'C and at 37°C and humidity was checked weekly with a dewpoint apparatus. Procer11rrrr.e for S~rruiualTests A virus suspension was removed from the -70°C freezer and melted, and 0.2-ml amounts were pipetted onto 2.5-cmZ glass nlicroscope slides contained in the humidity chanlbers. The slides in the low and medium humidity chambers dried within 30 min; slides in the high humidity chamber remained partially wet during
the entire test. In a preliminary trial, half of the chambers were placed 60 cm under one 100-W incandescent light bulb during the entire test period, and the other half were kept in complete darkness. Although light appeared to be a factor as shown in Table 1, it was eliminated from the remainder of the study because of our inability to adequately measure and monitor intensity. Therefore, in all subsequent experiments, the humidity chambers were stored in darkness and exposed to light only when slides were removed. At desired intervals, one slide from each chamber was removed and placed into a 32- x 200-mm test tube containing 20 ml of MEM plils 2 Z CS and shaken vigorously. The suspension was designated the lo-' dilution of the original virus suspension. Subsequent dilutions were made in MEM plus 2% CS and 1-ml quantities were transferred directly into cell-culture test tubes when tube assays were performed. Dilutions including the initial collection of virus were made with Hanks' BSS when a plaque assay was being performed. Assay Procecllrre Adenovirus, coxsackie, and vaccinia viruses were assayed by tube techniques using 10-fold dilutions, with four replicate cell-culture tubes at each dilution. Virus titer, as cell culture 50% infective dose (CCID,,/rnl), based on cytopathic effect (CPE) observed, was deter-
TABLE 1 Adenovirus-2 survival on various surfaces under varying light and relative humidity conditions at 37°C CCID5,/slide4 93% RH Time
Tileh
LightC
Dark
Ih
A B C D
106.0 105.75 106.0 106.0
106.5 106.0 106.0 105.75
1 week
A B C D
NVDd NVD NVD NVD
3 weeks
A B C D
NVD NVD NVD NVD
104.75 105.5 104.~ 104.~ 102.25 102.75 101.75 101.75
6 weeks
A B C D
NVD NVD NVD NVD
8 weeks
A B C D
NVD NVD NVD NVD
7% Mi Light
Dark
.Initial concentration o f 1 0 6 . 7 5 CCIDSo/slide. bA = glass. B = vinyl asbestos floor tile. C = ceramic tile. D = stainless steel. Cone 100-W incandescent light bulb 60 cm above the chambers. dNo virus detected. sensitivity o f assay was 101.5 CCIDSo.
821
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M A H L A N D SADLER: V I R U S S U R V I V A L
tests were performed using glass slides. The experimental design was expanded to include two temperatures (25°C and 37°C) and three humidities, 93%, 55%, and 7%. Five viruses were studied under these conditions and the results are shown in Tables 2-6. Adenovirus-2 survival was followed for 12 weeks and virus recovery was found possible under conditions of low humidity (Table 2). Herpes simplex virus and poliovirus-2 survived for at least 8 weeks under low humidity conditions (Tables 3 and 4). Vaccinia and coxsackievirus B3 survived for a shorter time, 3 to 4 weeks, and the influence of humidity was not observed (Tables 5 and 6).
mined by the Karber technique (7). Herpes and poliovirus were assayed by plaquing techniques whereby 1 ml of the dilution was pipetted onto cell-culture monolayers grown in Falcon 35-mm plastic plates. After a 2-h absorption period, the liquid was decanted and replaced with 2 ml of MEM plus 1% CS plus 0.2% gamma globulin (Cutter Laboratories, Berkeley, California). At the end of 5 days of incubation in a 5% C 0 2 atmosphere at 37"C, the medium was removed, cell sheets were fixed with methyl alcohol and stained with Giemsa stain, and plaques were counted.
Results Adenovirus-2 was studied in a preliminary test to determine the effects of the type of environmental surface on survival of the virus. Vinyl floor tile, ceramic tile, stainless steel, and glass microscope slides were cut into 2.5-cm squares and sterilized by autoclaving. Results are summarized in Table 1. Viable adenovirus-2 persisted on the slides for at least 8 weeks when held at low humidity (Table I), but remained on the slides less than 1 week in the dark at high humidity. Type of surface was not shown to be critical and further
Discussion The above data confirm and extend the findings of others that viruses can indeed persist weeks and even months on inanimate surfaces under ambient conditions of temperature and humidity. The types of common surfaces which
TABLE 2 Survival of adenovirus-2 on glass slides at three relative humidities and two temperatures CCIDSo/slidea Condition
4h
1 day
1 week
2 weeks
4 weeks
8 weeks
12 weeks
25°C
96x RH 55% R H 7% RH
107.5 107.5 107.5
108.25 108.0 107.5
106.75 107.75 106.25
106.0 lo5 107.~
107.~ 107.25 107.25
102.75 104.75 105.25
NVDb NVD 104.75
37°C
93% R H 55% R H 3y0RH
108.0 108.75 107.5
107.75 106.75 107.25
107.~ 106.0 107.25
107.0 106.75 106.75
102.5 104.5 106.25
103.75 l ~ 105.5
~
NVD . ~ NVD 104.75
Olnitial slides recerved 108.0CCIDSo. bNo virus detected (less than 10' 5 CCIDSo).
TABLE 3 Herpes simplex virus survival on glass slides at three relative humidities and two temperatures Plaque-forming units (PFU)/slidea
25°C
37°C
Condition
4h
1 day
1 week
2 weeks
6 weeks
8 weeks
96% R H 55% R H 7% R H 93% R H 55% R H 3% R H
1 . 5 105 ~ 9 . 9 lo4 ~ 1.5x103 8.1 x104 8 . 9 lo4 ~ 2 . 1 x103
4 . 5 lo3 ~ 4 . 5 lo3 ~ 1 . 2 lo2 ~ NVD NVD 5 . 2 10' ~
NVDb NVD 2 . 0 lo3 ~ NVD NVD 1 . 3 lo3 ~
NVD NVD 3.9x103 2.3 x lo3
6 . 2 10' ~ 1.8x102
9.2 x 10' -
'1Initlal sltdes received 3.7 x 105 PFU. bNo virus detected at the lowest detection limit of 100 PFU.
-
1 . 3 l~o 3
822
CAN. J . MICROBIOL. VOL. 21, 1975
TABLE 4 Poliovirus-2 survival on glass slides at three relative humidities and two temperatures
Condition
4h
1 day
1 week
2 weeks
4 weeks
6 weeks
8 weeks
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--
9 6 % ~ 8~ . 0 ~ 1 0 ~ 1 . 2 ~ 1 0 ~ 4 . 1 ~ 1 0 ~ 6 . 0 ~ 1 0 ~ 1 . 0 ~ 1 0 ~ N V D ~ 55zRH 1.2x108 8.7x107 6.6x105 7.4x103 NVD NVD 7%RH 1.6x106 1.1x106 7.5x105 3.2x105 2.9x104 7 . 0 104 ~
25°C
37"~
9 3 % ~ ~1 . 0 ~ 1 0 ~ 4 . 6 ~ 1 0 ~ NVD 55% RH 8 . 0 lo7 ~ 8 . 0 lo6 ~ NVD 3ZRH 5.0x105 1.0x105 8.6x103
nlnitial slides received 1.2 x 10BPFU. bNo virus detected at the lowest detection limit of
NVD NVD 1.1x103
-
-
-
1.7x103
3.1x103
NVD -
2.0x102
2.1x103
PFU.
TABLE 5 Vaccinia virus survival on glass slides at three relative humidities and two temperatures
25°C
37°C
Condition
4h
1 day
1 week
2 weeks
3 weeks
4 weeks
5 weeks
96% RH 55% RH 7% RH 93% RH 55% RH 3% RH
106.5 106.0 106.0 105.75 106.5 106.0
106.5 106.5 106.25
106.5 105.75 105.75
1O5.O 104.0 105.5
104.~ 102.5 103.5
104.~ 102.0 103.5
102.5 NVDb 102.0
103.75 103.75 103.5
102.5 103.25 103.25
103.~ i ~ ~ 103.25
io3.0 1.0 3 .~~ 102.75
102.5 102.0 102.0
NVD NVD NVD
olnitial slides received CCID,,. CCID50). bNo virus detected (less than
TABLE 6 Coxsackie virus B3 survival on glass slides at three relative humidities and two temperatures
25°C
37°C
Condition
4h
1 day
1 week
2 weeks
96% RH 55% RH 7% RH 93% R H 55% R H 3% RH
106.25 106.5 104.75
105.25 105.25
10 4 . ~ 105.0 102.25
l ~ 102.25 102.5
103.25 103.~ 102.0
102.0 102.0 102.0
105.75 106.0 104.~
104.5 104.O 105.25 103.~
3 weeks ~
. NVD ~ NVD NVD NVD NVD NVD
'Initial slides received 106.25CCID,,. virus detected (less than 10'~3CCC130).
were tested did not have an effect on adenovirus survival. Survival of vaccinia and poliovirus on fabrics has been extensively studied by Sidwell and Dixon (2, 9), who found these viruses t o persist for many weeks in the dark on various types of fabrics (e.g. wool and cotton). They also found that the viruses survived better a t 35%
relative humidity (RH) than a t 78% R H a t 25°C. Hendley et al. (4) showed that volunteers could be infected by rhinovirus on fingertips rubbed over surfaces upon which virus had been dried. The public health significance of the survival of viruses on surfaces has not been fully explored.
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MAHL AND SADLER: VIRUS SURVIVAL
The work reported in this study shows that viruses can survive for weeks O n surfaces under temperature and humidity. Because viruses can remain viable and thus potentially infectious for long times, inanimate surfaces should be considered as a factor in virus transmission. 1. BUCKLAND,F. E.,andD. A. J. TYRRELL. 1962. Lossof infectivity on drying various viruses. Nature (Lond.), 195: 1063-1064. 2. DIXON. G. J., R . W. SlDwELL,and E. MCNEIL.1966. Quant~tat~ve studies on fabrics as disseminators of vlruses. 11. Persistence of poliomyelitis virus on cotton and wool fabrics. Appl. Microbiol. 14: 183-188. 3. E D W A R DD., G. 1941. Resistance of influenza virus to drying and ~ t sdemonstration on dust. Lancet, 241: 664-666. 4. HEWDLEY,J . O., R. P. WENZEL, and J. M. GWALTNEY, JR. 1973. Transmission of rhinovirus
5, 6. 7.
8. 9.
10.
823
colds by self-inoculation. New Engl. J. Med. 288: 1361-1364. KIBRICK, S . 1959, The persistence of virus in the environment of patients with Kaposi's varicelliform eruption. J. Dis. Child. 98: 609-61 I . KINGSTON, D. 1968. Towards the isolation of respiratory syncytial virus from the environment. .I. ~ p p l . Bacte~.iol.31: 498-5 10. LENNETTE,E . H., and N. J. SCHMIDT. (Edito~.~.) 1964. Diagnostic procedures for viral and rickettsia1 diseases. %d ed. American Public Health Association. pp. 47-50. PARKER, E. R., and W. J. MACNEAL.1944. Persistence of influenza virus on the human hand. J. Lab. Clin. Med. 29: 121-126. S I D W E L LR., W., G. J . DIXON, and E. MCNEIL.1966. Quantitative studies on fabrics as disseminators of viruses. 1. Persistence of vaccinia virus on cotton and wool fabrics. Appl. Microbiol. 14: 55-59. WINSTON, P. W., and D. H. BATES.1960. Saturated solutions for the control of humidity in biological research. Ecology, 41: 232-237.
