Rare and unusual symptoms of novel coronavirus (SARS-COV-2 and COVID-19) infection: vomiting and diarrhea (a speculation) and the evolution of the symptoms of disease

(image courtesy of pixabay)

Cough, usually dry, upper respiratory symptoms, chest pain and tightness, and dyspnea (shortness of breath) are typical symptoms of the novel coronavirus known as SARS-COV-2 (the disease it causes is officially called COVID-19).  The official WHO (World Health Organization) list of symptoms includes headache (I think) and nausea, but it does not include vomiting, abdominal pain, or diarrhea.  It also does not include anosmia (loss of the sense of smell), although this is a common symptom of many infections that are caused by other coronaviruses like the common cold.

There may be an evolution of symptoms, from runny nose to sore throat to cough, with a delay in the development of cough and shortness of breath related to lung infection.  It may take a week or more for pneumonia to develop.  The original case reports from Wuhan were specifically for an atypical form of pneumonia (reticulonodular densities on the CAT scan) and this drove most people’s thinking from the beginning.  But pneumonia is only an extreme end of the symptom spectrum.

It is said that 80% of people will have “mild” symptoms, but this elides the possibility that one may have no symptoms at all.  Asymptomatic persons may transmit the infection to other people, with an unknown degree of risk.  Probably an asymptomatic person would carry less virus and thus be less contagious to others, but this is not guaranteed.  The virus will see an advantage in having a proportion of its victims have no symptoms, yet be contagious.  Because of this advantage, it is likely that the virus has already evolved the ability to go through some people with no symptoms and spread to others.  If it has not already evolved, it is almost certain that eventually the virus will acquire this ability and learn to circulate throughout the human population without causing symptoms or only trivial symptoms.  Then it will be just another form of the common cold, of which four different coronaviruses already cause a third of cases.

There is a good theoretical basis for thinking that the virus also infects the GI (gastrointestinal) tract, and virus can be detected in the feces.  In rare cases, patients who are proven to have COVID-19 may have (or have had) vomiting and diarrhea; this is usually ignored by doctors but not by patients.  Abdominal pain, although it could be present in those cases, should not be significant unless the bowel wall is penetrated.  It may be that a few people, whether due to their route of exposure or due to their peculiar genetic makeup, have virus infection localized to the GI tract.  Only close study over a period of time will resolve this question.  It is important for us to know if transmission through feces is likely, because we have to take precautions in handling our waste water.