Download FMD Skin Aerosols Supplemental Material Other Viral Diseases

FMD Skin Aerosols
Supplemental Material
Other Viral Diseases
Supplemental Material: Other Viral Diseases
Manuscript Title: Skin as a Potential Source of Infectious Foot and Mouth Disease Aerosols
The biological plausibility of FMDV transmission via infectious skin cell is enhanced if a skin
cell source of disease transmission has been established (or is likely) for other viruses. FMD is
not the only viral pathogen for which (a) there is known skin trophism (e.g. rash or lesions), (b)
the respiratory tract is known to be a significant (or dominant) infectious pathway, and (c) viral
transmission is present co-incident with the skin trophism (often peaking with the skin trophism
onset).1 For example, airborne transmission of Marek’s disease (a herpesviridae affecting
poultry) is known to be associated with desquamated epidermal cells shed from feather follicles
[S1]. In addition, a number of human viruses,2 from several virus families, are well known to
share these traits, including herpesviridae, e.g. Varicella-Zoster (chickenpox) [S2]; poxviridae,
e.g. Variola Major and Minor (smallpox) [S3]; togaviridae, e.g. Rubivirus (rubella), and
paramyxoviridae, e.g. Measles [S4].
Published data on Varicella-Zoster Virus (VZV) is particularly relevant to the current discussion.
VZV is the cause of chickenpox and reactivation of dormant viral infection later in life causes
localized cutaneous herpes zoster. VZV is believed to be transmitted by direct contact via
fomites contaminated by the infected serous exudate from ruptured skin vesicles, but an
important secondary route of transmission is hypothesized to be the airborne route via infected
skin scales [S2].3 VZV is detected in air samples taken from patient rooms and nearby locations.
This is true both in room air samples for patients with widespread rashes (primary varicella) as
well as in room air samples for cases presenting solely as a localized skin rash (reactivated local
cutaneous herpes zoster) [S8,S9,S10,S11]. VZV DNA is also detected in environmental dust
samples obtained up to 1.5 months after the clinical development of a rash [S11,S12]. Suzuki et
al. [S10] demonstrated that when localized VZV rashes were covered with an impenetrable
(hydrocolloid) dressing, viral samples from the patient’s throat, the ambient room air, and outer
surface of the dressing were nearly universally negative for VZV. In contrast, the corresponding
samples from patients using standard gauze dressings (which are not expected to retard skin
aerosol emissions) were nearly universally positive. Earlier work [S9] indicated that the
sequence of positive virus detections progressed first from the patient’s skin, then to ambient air
samples and then to patient throat samples – suggesting that airborne VZV skin aerosols may be
a source of disease transmission.
The data for variola major and minor (smallpox) is more circumstantial. The respiratory system
is well-known to be the typical site of initial infection, but the aerosol generation pathway is not
well understood [S3]. High viral levels are found in respiratory secretions during periods of high
infectivity, suggesting a respiratory emission pathway. However, this period is also co-incident
with the onset of the rash. Published studies [S13,S14] suggest that infectious aerosol emissions
1
This screening criteria does not attempt to distinguish between infected material residing within or outside the skin
cell aerosols (the latter would be expected from surface contamination via ruptured lesion).
2
For human diseases, inhalation of virally infected skin cells may be a particularly efficient mechanism of disease
transmission due to 1) the high (1 to 10%) fraction of indoor dust that is comprised of human skin fragments, 2) the
large amount of time people spend indoors [S5], and 3) the known ability for large (>10 μm) aerosols to be inhaled
by humans [S6].
3
The degree to which respiratory emissions contribute to the overall disease transmission in primary VZV infection
is still a point of debate [S7].
Dillon, M.B.
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Supplemental Material
Other Viral Diseases
are primarily associated with relatively large aerosols (skin cell size) and the disturbance of
bedsheets (which would harbor skin cells). Air samples taken near patients’ mouths yielded
relatively little virus. The composition of the carrier aerosol(s) has not been elucidated. We are
unaware of a study that examined the concentration, lifetime, or infectivity of the variola virus in
intact stratum corneum. However, it is well known that the variola virus can remain infectious
for over 10 years in scab material, although scab-bound virus infectivity is low [S3].
Auspices
This work performed under the auspices of the U.S. Department of Energy by Lawrence
Livermore National Laboratory under Contract DE-AC52-07NA27344.
Dillon, M.B.
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Supplemental Material
Other Viral Diseases
References:
[S1] Biggs P.M. 2001 The History and Biology of Marek’s Disease Virus. In Marek’s Disease
(ed. K. Hirai), pp. 1-24, New York: Springer-Verlag (ISBN 3-540-67798-4).
[S2] Breuer J. 2008 Herpes Zoster: New Insights Provide an Important Wake-up Call for
Management of Nosocomial Transmission. Journal of Infectious Diseases. 197, 635-636
(doi: 10.1086/527421)
[S3] Fenner, F., D.A. Henderson, I. Arita, Z. Jezek, and I.D. Landnyi 1988 Smallpox and its
Eradication, World Health Organization (ISBN 92 4 156110 6)
[S4] Baron S. (Ed.) 1996 Medical Microbiology, 4th edition, University of Texas Medical Branch
at Galveston, ISBN: 0-9631172-1-1
(http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=mmed)
[S5] Klepeis N.E, Nelson W.C., Ott W.R., Robinson J.P., Tsang A.M., Switzer P., Behar J.V.,
Hern S.C. & Engelmann W.H. 2001 The National Human Activity Pattern Survey
(NHAPS): A Resource for Assessing Exposure to Environmental Pollutants. Journal of
Exposure Analysis and Environmental Epidemiology 11, 231-252 (doi:
10.1038/sj.jea.7500165)
[S6] Dai Y., Juang Y., Wu Y., Breysse P.N. & Hsu D. 2006 In Vivo Measurements of
Inhalability of Ultralarge Aerosol Particles in Calm Air by Humans. Journal of Aerosol
Science 37, 967-973 (doi:10.1016/j.jaerosci.2005.10.002)
[S7] Mehta S.K., Tyring S.K., Gilden D.H., Cohrs R.J., Leal M.J., Castro V.A., Feiveson A.H.,
Ott C.M. & Pierson D.L. 2008 Varicella-Zoster Virus in the Saliva of Patients with
Herpes Zoster. The Journal of Infectious Diseases 197, 654 –657 (doi: 10.1086/527420)
[S8] Sawyer M.H., Chamberlin C.J., Wu Y.N., Aintablian N. & Wallace M. 1994 Detection of
Varicella-Zoster Virus DNA In Air Samples From Hospital Rooms. Journal of Infectious
Diseases 169, 91-94
[S9] Suzuki K., Yoshikawa T., Tomitaka A., Suzuki A., Matsunaga K. & Asano Y. 2002
Detection of Varicella-Zoster Virus DNA in Throat Swabs of Patients with Herpes Zoster
and on Air Purifier Filters. Journal of Medical Virology, 66 567-570 (doi:
10.1002/jmv.2182)
[S10] Suzuki K., Yoshikawa T., Tomitaka A., Matsunaga K. & Asano Y. 2004 Detection of
Aerosolized Varicella-Zoster Virus DNA in Patients with Localized Herpes Zoster. The
Journal of Infectious Diseases, 189, 1009-1012 (doi: 10.1086/382029)
[S11] Yoshikawa T., Ihira M., Suzuki K., Suga S., Tomitaka A., Ueda H. & Asano Y. 2001
Rapid Contamination of the Environments with Varicella-Zoster Virus DNA from a
Patient with Herpes Zoster. Journal of Medical Virology 63, 65-66
Dillon, M.B.
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Other Viral Diseases
[S12] Lopez A.S., Burnett-Hartman A. & Namabiar R. 2008 Transmission of a Newly
Characterized Strain of Varicella-Zoster Virus from a Patient with Herpes-Zoster in a
Long Term Care Facility, West Virginia, 2004. Journal of Infectious Diseases 197, 646653 (doi: 10.1086/527419)
[S13] Downie A.W., Meiklejohn M., St. Vincent I., Rao A.R., Sundara Babu B.V. & Kempe
C.H. 1965 The Recovery of Smallpox Virus from Patients and their Environment in a
Smallpox Hospital. BWHO 33, 615-622
[S14] Thomas G. 1974 Air Sampling of Smallpox Virus. J. Hyg. Camb., 73, 1-8
Dillon, M.B.
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