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Corresponding author. Address: Maximum Containment Facility, Indian Council of Medical Research – National Institute of Virology, Sus Road, Pashan, Pune, Maharashtra, 411021, India. Tel.: +91-20-25906911; fax: +91-20-25906669.
]. We performed a study to determine the persistence of mpoxv on surfaces of the isolation ward during August–November 2022. In total, eight confirmed mpox cases were isolated in an mpox isolation ward at a tertiary care hospital in New Delhi, India. The surface sampling was conducted on alternate days until the samples tested negative from 38 surfaces of the hospitals from four main zones: zone 1 (donning room), zone 2 (mpox isolation ward), zone 3 (washroom), and zone 4 (doffing room) (Figure 1). Before the environmental sampling, informed consent was obtained verbally by all the eight admitted mpox cases in the ward.
Figure 1The layout of mpox isolation ward and surface sampling.
The viral kinetics of the surface samples were compared with the viral load in clinical specimens of human mpox cases. The clinical specimens, i.e. oropharyngeal swab (OPS), nasopharyngeal swab (NPS), lesion samples, serum, EDTA blood, and urine were collected every fourth day until the specimens tested negative. Informed written consent was obtained before collecting clinical specimens. All the samples were transported to ICMR-National Institute of Virology, Pune, and tested using mpox-specific real-time polymerase chain reaction (PCR) [
All the mpox cases had multiple vesiculo-pustular lesions primarily on their genitals, trunk, face, back, and limbs. However, none of the patients had vomiting, diarrhoea, cough, sneezing, and respiratory distress. Higher viral load was observed in lesion samples of all eight cases (1.1×108 to 7.4×1010 copies/mL) at the time of admission, while NPS/OPS showed detectable viral load in six cases (1.7×105 to 7.7×107 copies/mL). Similarly, urine samples were also positive among seven cases (7.1×106 to 4.4×109 copies/mL). The persistence of viral DNA was observed in lesion samples (2×106 copies/mL) until the 23rd post-onset day of illness (POD), while OPS/NPS and urine also had detectable levels of viral DNA till 22nd (1.8×105 copies/mL) and 23rd (2.8×105 copies/mL) POD respectively.
The specimens collected from the surfaces near the vicinity of the bedside of all the cases showed viral DNA positivity (8.6×104 to 1.2×108 copies/mL) even after their lesion samples turned negative. Additionally, positivity for mpoxv DNA (8.6×104 to 6.1×107 copies/mL) was recorded at environmental sites and touch points, e.g. floor (5–500 m), door surfaces, door knob, window surfaces, window knob, biohazard bin, and electric switches. Similarly, equipment also demonstrated persistence of viral DNA including on the gloves of healthcare workers following patient care activities (8.0×105 copies/mL), stethoscope (2.8×105 copies/mL), ventilator surface (5.3×105 copies/mL), sphygmomanometer (5.9×106 copies/mL), critical vitals monitors (6.9×105 copies/mL), intravenous stand (2.2×106 copies/mL), bedside table tops (1.7×106 copies/mL), treatment tray (3.3×106 copies/mL), and food trolley (9.7×106 copies/mL). The high-touch surfaces (basin, water tap, trash can, commode, and bucket) in the washroom also showed the presence of viral DNA ranging from 9.3×104 to 1.1×108 copies/mL with highest viral load on commode surfaces. However, no mpoxv was detectable from the surfaces of the donning room, whilst the doffing room demonstrated detectable viral DNA (8.6×104 to 7.8×106 copies/mL) (Figure 1).
The surface samples with high viral load of >104 DNA copies/mL were also cultured using Vero CCL-81 cell line to determine the viability of the virus [
]. The mpoxv was cultured using swabs collected from the bed (N = 1), linen (N = 2), bed rails (N = 1), floor (below bed) (N = 1) on 6th–8th POD of one patient with viral load in the range of 3.9×106 to 3.0×107 copies/mL. The viral DNA positivity (4.4×106 copies/mL) and positive mpoxv cultures were also obtained from the washroom surface, i.e. bucket (N = 1) on 6th POD of the same case. This mpox patient had a higher viral load in lesion samples (1.9×109 DNA copies/mL) at 5th POD (day of admission) with vesiculo-pustular lesions on face, upper arms, lower limb, trunk, back, and genitals.
Previously, Gould et al. have also reported widespread contamination on hospital surfaces occupied by individuals with symptomatic mpox [
]. This study has also shown that viable virus can be detectable on the surfaces of the isolation ward for up to one week following admission of an mpox-infected patient. However, although DNA positivity by PCR was detectable until the last collection point (29th POD), viable mpoxv was not cultured from the surface samples. This study further reinforces the importance of surface cleaning protocols with twice daily cleaning of the isolation ward, washroom, high- touch surfaces, as well as good doffing procedures for personal protective equipment to avoid the onward transmission among healthcare workers and cleaning staff. Second, the persistence of mpoxv DNA near the patient bed and its vicinity reiterates the need for frequent changes in bed linen and covers along with correct handling of the infected laundry to reduce exposure. Appropriate hand hygiene practices, followed by surface disinfection of the patient care equipment, would also be important to reduce onward transmission. Overall, this study demonstrates the detection of mpox viral DNA and infectious virus from the surfaces of the isolation ward supporting the requirement of rigorous hospital infection control practices.
Ethical approval
The study was approved by the Institutional Human Ethics Committee of ICMR-National Institute of Virology, Pune, India under the project ‘Providing diagnostic support for referred samples of viral haemorrhagic fever and other unknown aetiology and outbreak investigation’. The clinical data collected were anonymized. The written informed consents were obtained from all the cases under study for the use of the clinical specimens and clinical history. Informed verbal consents were also obtained from patients before collecting the environmental samples in the isolation ward. The study was also approved by Institutional Biosafety Committee of ICMR-National Institute of Virology Pune.
Acknowledgements
Authors extend gratitude to Dr (Prof.) P. Abraham, Former Director, ICMR-National Institute of Virology Pune for continuous support throughout the study. We also acknowledge the excellent technical support from Mrs S. Sathe, Ms V. Kumari, Mr R. Lakra, Ms U. Gaikwad, Ms R. Dhote, and Ms N. Shende from the Maximum Containment Facility for the diagnosis and data management. The authors are grateful to all the study participants for providing the consent and sharing their valuable samples.
Author contributions
P.D.Y. and R.R.S. contributed to study design, data analysis, interpretation, writing and critical review. V.R., R.R.S., A.M.S., D.Y.P., L.P.K., A.K., T.M., D.A., P.G., G.L., J.Y., A.B., P.V., A.G., P.S., P.G.M.R., H.D., A.K., R.J., D.M. contributed to sample collection, data collection, interpretation, writing and critical review. P.D.Y., D.Y.P., R.R.S., A.M.S., V.R., B.S., S.K. contributed to the critical review and finalization of the paper.
Conflict of interest statement
None declared.
Funding sources
An intramural grant was provided from ICMR-National Institute of Virology, Pune for conducting this study.
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Longitudinal mpox virus surface sampling in an outpatient setting.
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