By Dr Arun K Dubey, MD and J. Joseph PhD
The symptoms this virus causes usually start with sore throat and fever, becoming worse with dry cough and respiratory distress.
Corona viruses (CoV) are a large family of human and animal viruses. Milder human corona virus types cause common cold. Others such as the SARS-CoV and MERS-CoV are of bat origin, pass to humans through intermediate animal hosts and cause severe respiratory illness characterized by pneumonia and respiratory distress. The current pandemic is due to a SARS Cov-2 (~90% genetically similar to SARS CoV of 2003) that presumably appears to have originated in late December 2019 from an alleged wild-life market in Wuhan, capital of Hubei province of People’s Republic of China that sells exotic animals’ meat as a common practice there then. Today, it has spread to more than 180 countries and has infected ~5 lakh people with more than 19000 deaths.
SARS Cov-2 is acquired most commonly by exposure to respiratory aerosols from symptomatic patient(s) or asymptomatic incubatory carrier(s) [people who are infected and don’t show disease symptoms, but transmit the virus]. SARS Cov-2 has an R0 (Reproduction number of virus) of 2.3, which means that a person with a SARS Cov-2 infection would likely transmit the virus to 2.3 people on an average (almost double as that of flu, R0 = 1.3). The incubation period (time interval between acquisition of the virus till onset of symptoms) of SARS Cov-2 can range anywhere between 2-14 days (average, 5 days). The virus initially colonizes and proliferates in the upper respiratory tract that manifests as a sore throat usually accompanied by a fever around a week of infection, after which, the virus descends down the windpipe to the lungs where it causes damage to the lung substance and lead to symptoms such as non-productive cough and respiratory distress (can manifest as severe difficulty in breathing, bluish lips). Less concerning symptom(s) such as fatigue, chills, sniffles, headaches and diarrhea may be seen in some cases. However, in severe cases, especially in elderly individuals (>60 years of age) with pre-existing cardiovascular or lung disease(s) or other comorbidities such as diabetes &/or hypertension, complications such as pneumonia and respiratory failure can result.
However, it is to be strongly noted that approximately 40% of SARS Cov-2 patients requiring hospitalization are in the 29-59 year age group, deluding previous claims that the disease is not of a serious concern in the younger age group. The disease is infectious to others at all stages. The SARS Cov-2 mortality rate in Wuhan, the epicenter of the global outbreak is ~2%, whereas in worst hit Italy, it is worrisome, currently soaring at 9.6%. The global SARS Cov-2 mortality rate however stands close to 4% and in USA, it is 1.4%. It is clear that more than three-fourths of the deaths are reported in people over 65 years of age.
Currently, the management of critically ill cases is with supportive care such as oxygenation and mechanical ventilation. Chloroquine and hydroxychloroquine therapy seems promising to improve survival in the patients as evidenced by Wuhan outcomes. Milder cases can be symptomatically managed with fever medications. More than a dozen leading biotechnological and pharmaceutical giants are getting closer to developing a vaccine against SARS Cov-2, giving hopes of an effective prophylaxis.
With community transmission of SARS Cov-2 gaining momentum, isolating and quarantining cases and their contacts is the single most effective measure that can prevent the spread. Robust screening and testing of symptomatic and suspected cases is essential to curb the mortality in vulnerable age groups. Health care professionals are already playing a crucial role in the control of the epidemic in their respective countries. The stringent medical and social practices need to be followed with utmost dedication to flatten the curve of infected cases. Adequate safe hygienic practices such as handwashing and strict social distancing is the need of the hour to win the war over this invincible enemy.
Dr Arun K Dubey is Chief Academic Officer and J. Joseph Assistant Professor, both at Xavier University School of Medicine, Aruba (XUSOM).