The epidemic disease, also called “Severe Acute Respiratory Syndrome-2 (SARS-CoV-2)” or “Coronavirus Disease-19 (Covid-19)”, was first reported from Wuhan, China at the end of December 2019 and affected the world in a short time and was declared as a “Global Pandemic” by the World Health Organization in March 2020. Coronaviruses are enveloped RNA viruses and belong to the Coronaviridae family. The SARSCoV-2 virus, which contains four main structural proteins, namely spike surface glycoprotein and small envelope-matrix-nucleocapsid proteins, binds to receptors in the body via spike surface proteins. The SARSCov-2 virus is able to act by binding to ACE-2 receptors, which are part of the Renin-Angiotensin-Aldosterone System (RAAS), a hormonal system that regulates blood pressure and fluid balance in the body. However, the SARSCoV-2 virus can bind to ACE-2 by activating another important molecule, Transmembrane Serine Protease 2 (TMPRSS2), by interrupting the spike protein. Following the binding of the virus, ACE 2 expression decreases and the amount of Angiotensin II in the cell increases. Many other organs besides the lungs also contain ACE 2 receptors. Therefore, this increase causes many damages, including acute respiratory distress, inflammation, myocardial (heart muscle) damage and histopathological changes including gastrointestinal repercussions. The spectrum of the disease can vary from simple colds to severe acute respiratory syndrome in humans. It can cause clinical pictures in humans and animals with various degrees of lung, gastrointestinal system, liver, kidney and nervous system involvements.
The Covid-19 virus can be spread from human contact with animals. Human-to-human transmission is mainly through droplets. In addition, the droplets that the sick individuals emit by coughing and sneezing are transmitted by contact with the hands of other people and then taking their hands to the mouth, nose or eye mucosa and contacting them. Since the virus can also be detected in the respiratory secretions of asymptomatic people, it can be contagious. It has been observed that the average incubation period is 5-6 days, in some cases it can extend to 14 days. The duration of the transmission of Covid-19 is not known with certainty. It is believed that it begins 1-2 days before the symptomatic period and ends with the disappearance of symptoms.
The World Health Organization (WHO) recommends taking the following measures for effective prevention from Covid-19.
If you are sick, isolate yourself, do not be in crowded places, protect your environment with masks that cover the mouth and nose when necessary.
Covid-19 can also give clinical symptoms in the form of mild symptoms such as fever, cough, sore throat, muscle pain, fatigue and severe symptoms such as pneumonia, acute respiratory distress syndrome, renal failure, multiple organ failure, which require advanced intensive care.
Covid-19 virus can be detected by reverse transcriptase polymerase chain reaction (RT-PCR) in a swab taken from the nasal or oropharyngeal regions. However, if possible, tracheal aspirate or bronchoscopic samples should be preferred for samples to be taken from the lower respiratory tract. Samples taken from the lower respiratory tract are more likely to detect the virus. In cases where NAATs (nucleic acid amplification tests) are negative and have a strong epidemiological relationship with Covid-19 infection, the study of serological tests on serum samples taken in the acute and/or convalescent phase may support the diagnosis. For this purpose, serological tests such as ELISA or rapid antibody tests that detect IgM/IgG are already used.