Molecular evidence of SARS-CoV-2 detection on cockroaches in Shiraz, southwestern Iran and potential implications for mechanical carriage
4 affiliations
- 1Department of Medical Laboratory Sciences, School of Paramedical Sciences, Shiraz University of Medical Sciences, Shiraz, Iran
- 2Student Research Committee, Department of Medical Entomology and Vector Control, School of Health, Shiraz University of Medical Sciences, Shiraz, Iran
- 3Clinical Microbiology Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
- 4Research Center for Health Sciences, Institute of Health, Department of Medical Entomology and Vector Control, School of Health, Shiraz University of Medical Sciences, Shiraz, Iran; Corresponding author.
Abstract
Cockroaches are known vectors of various pathogens due to their unsanitary feeding habits and close association with human habitats. The COVID-19 pandemic has raised concerns about potential non-human transmission routes, including mechanical transmission by insects. This study investigates whether cockroaches can carry SARS-CoV-2 RNA and their potential role in mechanical transmission in Shiraz, Iran. Using real-time RT-PCR (positivity threshold: Ct < 38.0 for both RdRp and N genes), we molecularly examined 200 cockroaches (100 Blattella germanica and 100 Periplaneta americana ) randomly selected from a total of 400 collected specimens. An additional 200 specimens were allocated to insectarium-based vertical transmission experiments. SARS-CoV-2 RNA was detected on external surfaces of 59/200 specimens (29.5%; 95% CI: 23.4–36.3%), with significantly higher detection in P. americana from hospital sewage (35/50, 70%; 95% CI: 55.9–81.2%) than B. germanica from dormitory kitchens (24/50, 48%; 95% CI: 34.2–62.2%; χ 2 = 5.01, p = 0.025). Internal viral RNA was detected in only 11/200 specimens (5.5%; 95% CI: 3.1–9.6%), with significantly lower loads than surface samples (mean surface-to-internal ratio: 15.2:1; p < 0.001). No viral RNA was detected in 200 nymphs or 50 egg capsules from insectarium-reared populations, indicating no evidence of transovarial transmission under experimental conditions. These findings demonstrate that cockroaches can carry SARS-CoV-2 RNA on their external surfaces, suggesting potential for mechanical carriage rather than biological transmission. However, as RT-PCR detects nucleic acids rather than infectious virus, our results do not establish mechanical transmission. Further research incorporating viral viability assays is needed to determine whether cockroaches can transmit infectious SARS-CoV-2 and contribute to COVID-19 epidemiology.
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BibTeX
@article{motevasel2026molecular,
title = {{Molecular evidence of SARS-CoV-2 detection on cockroaches in Shiraz, southwestern Iran and potential implications for mechanical carriage}},
author = {Maryam Motevasel and Mozafar Vahedi and Marzeyeh Jamalidost and Mohsen Kalantari},
journal = {Parasite Epidemiology and Control},
year = {2026},
month = oct,
doi = {10.1016/j.parepi.2026.e00558},
url = {https://doi.org/10.1016/j.parepi.2026.e00558},
note = {CC BY},
}
RIS
TY - JOUR
TI - Molecular evidence of SARS-CoV-2 detection on cockroaches in Shiraz, southwestern Iran and potential implications for mechanical carriage
AU - Maryam Motevasel
AU - Mozafar Vahedi
AU - Marzeyeh Jamalidost
AU - Mohsen Kalantari
PY - 2026
DA - 2026/10/23
JO - Parasite Epidemiology and Control
DO - 10.1016/j.parepi.2026.e00558
UR - https://doi.org/10.1016/j.parepi.2026.e00558
AB - Cockroaches are known vectors of various pathogens due to their unsanitary feeding habits and close association with human habitats. The COVID-19 pandemic has raised concerns about potential non-human transmission routes, including mechanical transmission by insects. This study investigates whether cockroaches can carry SARS-CoV-2 RNA and their potential role in mechanical transmission in Shiraz, Iran. Using real-time RT-PCR (positivity threshold: Ct < 38.0 for both RdRp and N genes), we molecularly examined 200 cockroaches (100 Blattella germanica and 100 Periplaneta americana ) randomly selected from a total of 400 collected specimens. An additional 200 specimens were allocated to insectarium-based vertical transmission experiments. SARS-CoV-2 RNA was detected on external surfaces of 59/200 specimens (29.5%; 95% CI: 23.4–36.3%), with significantly higher detection in P. americana from hospital sewage (35/50, 70%; 95% CI: 55.9–81.2%) than B. germanica from dormitory kitchens (24/50, 48%; 95% CI: 34.2–62.2%; χ 2 = 5.01, p = 0.025). Internal viral RNA was detected in only 11/200 specimens (5.5%; 95% CI: 3.1–9.6%), with significantly lower loads than surface samples (mean surface-to-internal ratio: 15.2:1; p < 0.001). No viral RNA was detected in 200 nymphs or 50 egg capsules from insectarium-reared populations, indicating no evidence of transovarial transmission under experimental conditions. These findings demonstrate that cockroaches can carry SARS-CoV-2 RNA on their external surfaces, suggesting potential for mechanical carriage rather than biological transmission. However, as RT-PCR detects nucleic acids rather than infectious virus, our results do not establish mechanical transmission. Further research incorporating viral viability assays is needed to determine whether cockroaches can transmit infectious SARS-CoV-2 and contribute to COVID-19 epidemiology.
SN - 2405-6731
ER -