Faced with the development of the Covid-19 epidemic, it appears that the ability of the SARS-CoV-2 coronavirus to pass from one organism to another has probably been underestimated. The analyzes carried out on Chinese patients make it possible to learn more about the vectors of transmission.
- Analysis of fluids taken from Chinese patients shows that the coronavirus can also be transmitted by the extra-respiratory route
- This is one of the explanations for the very rapid development of the Covid-19 epidemic.
The contagiousness, that is to say the ease with which the SARS-CoV-2 virus responsible for the Covid-19 epidemic can spread, has been partly underestimated because for a long time considered to be essentially by the respiratory route. .
A study of JAMA provides some information on this subject based on the analysis of 1,070 samples of different bodily fluids taken from 205 Chinese patients with severe conditions or under artificial respiration. The RNA was extracted from the samples according to the usual methods, in 3 hospitals in the provinces of Hubei, Shandong and Beijing.
Not just saliva
Most patients (mean age 44) had fever, dry cough, fatigue and 19% of them were seriously ill. Bronchoalveolar lavage fluid specimens showed the highest live virus positivity rates (14 of 15; 93%), followed by sputum (72 of 104; 72%), nasal swabs (5 of 8; 63%), brush sampling during fibroscopy (6 out of 13; 46%), pharyngeal swabs (cleaning the cavity using a small brush) (126 out of 398; 32%) , stools (44 of 153; 29%) and blood (3 of 307; 1%). None of the 72 urine samples tested positive.
In this study, SARS-CoV-2 was detected in all samples from 205 patients with COVID-19, except urine. Note that the nasal swab, which is the most common diagnostic means, is not the most efficient, while samples from the lower respiratory tract are most often positive for the virus.
Faecal contamination
Importantly, live virus was detected in feces, implying that SARS-CoV-2 can be transmitted through the feces. A small percentage of blood samples gave positive results, which may suggest that the infection can sometimes be systemic and contaminating the blood. These results are consistent with those of 2 others studies of lesser scope.
This transmission of the virus by the respiratory and “extra-respiratory” route can help explain the sometimes explosive spread of the disease, because associated with objects of everyday life, contaminated, or even to waste water. Finally, for physicians and epidemiologists, testing samples from multiple sites can improve diagnostic sensitivity and reduce false negative results.