Yesterday some information was released about a cat in
Belgium who lived with a Coronavirus-positive owner. It is very important to
prevent pet owners from becoming alarmed because there is no reason for it.
On March 18, 2020 (1), viral RNA from the SARS-CoV2 virus
was found in Belgium in the faeces and vomit of a cat with digestive and
respiratory symptoms. The cat lived in isolation after diagnosing SARS-CoV2 in
the owner.
Nevertheless:
- Other possible diseases that could cause the animal's
symptoms were not excluded.
- "Productive viral infection was suspected due to the large
number of copies of the viral genome and compatible clinical symptoms BUT,
detection of the SARS-CoV2 genetic material in the stomach contents and faeces
is not equivalent to active infection. Cats walk outside, are petted, and are
often brushed, making it easier for the patient's SARS-CoV2 genetic material
and the environment to enter the gastrointestinal tract. The presence of the
viral genome also gives no idea of the number of infectious particles. Virus
titration and seroconversion are better methods (and have not been done in this
case)."
- Idexx has done PCR tests on a large number of cats in
regions with COVID-19 and none was positive (2).
From this it follows that the risk to humans of potentially
being infected by a companion animal remains negligible.
Should I avoid contact with pets or other animals if I am
sick with COVID-19? The CDC (Centers for Disease Control and Prevention)
recommends the following:
“You should restrict
contact with pets and other animals while you are sick with COVID-19, just as
you would with other people. Although there have been no reports of pets or
other animals becoming ill with COVID-19, it is still recommended that people
sick with COVID-19 limit contact with animals until more information about the
virus is known.
Whenever possible, have another member of your household
care for your animals while sick. If you are sick with COVID-19, avoid contact
with your pet, including petting, snuggling, being kissed or licked, and
sharing food.
If you must care for your pet or be around animals while
sick, wash your hands before and after interacting with pets and wear a face
mask. ”
Check for new updates on the CDC website at www.cdc.gov/coronavirus/2019-ncov/faq.html#2019-nCoV-and-animals
This observation in the Belgian cat has once again
highlighted the difficulties we face when trying to identify an infectious
pathology as such, meaning the correlation between symptoms and the presence of
a causal agent. Relman and Fredericks suggested in 1996 "to consider the
degree of association between the pathogen and infected tissue" and "to
observe the correlation between the course of the disease and the amount of
pathogenic genetic material found". Since then, technology
has made available numerous ways to identify and quantify pathogens.
However, the rapid identification of these microorganisms sometimes leads to
erroneous conclusions.
Hosainzadegan et al. (4) conclude in a short review that it
is necessary to review these criteria again and suggest that “due to the
complicated relationships of the microorganisms with the host, simultaneously
implement and use pathological and immunological patterns that reflect
microbial changes in body indices (such as inflammatory cells, epithelial
cells, inclusion bodies and microbial morphologies) could be useful criteria to
qualify Koch's postulates regarding infectious and non-infectious diseases.”
The importance and particular characteristics of each
species’ (and individual’s!) immune system cannot be ignored despite technology allowing us to "portray" the pathogen and theorize about its compatibility with the host.
In conclusion: congratulations to the physiology of Felis
Catus, who manages NOT to contribute to COVID19 pandemic.
References:
1. CONSEIL URGENT 04-2020 – version
provisoire Objet :Risque zoonotique du SARS-CoV2 (Covid-19) associé aux animaux
de compagnie : infection de l’animal vers l’homme et de l’homme vers l’animal (Mandat
du Comité scientifique fédéral en charge de la gestion de la pandémie de
SARS-CoV2 en Belgique) (SciCom 2020/07) Conseil urgent provisoire approuvé
électroniquement par le Comité scientifique le 22 mars 2020
2.
https://www.idexx.com/en/veterinary/reference-laboratories/idexx-sars-cov-2-covid-19-realpcr-test/
Consultado 28/03/2020
3. Fredericks
DN, Relman DA. Sequence-based identification of micorbial pathogens: a
reconsideration of Koch’s postulates. Clin Microbiol Rev ; Jan 9(1): 18-33
(1996)
4. Hosainzadegan, H., Khalilov, R. & Gholizadeh, P. The
necessity to revise Koch’s postulates and its application to infectious and
non-infectious diseases: a mini-review. Eur J Clin Microbiol Infect Dis 39,
215–218 (2020).
