Viral shedding - Corona virus

Dr Laisram Immo Singh
We all join our hands for a common cause, a fight between man and microorganisms. I chose this topic because natural history of an organism would give us the origin and epidemiology of the disease, not forgetting the acute management. Nature, microorganisms and mankind evolved one after another, living together and helping one another. Microorganisms reside in the skin, mouth, oral cavity, intestine, urinary tract and all over the body. Pathogens are the ones that is harmful to man. Commensals are harmless, become pathogens when host becomes weak for defense like sickness. Microbes can gain entry into the host through air, water, food, formites etc. and enters the community. When they enter the community, they are called community acquired. They spread very fast causing damage everywhere. Influenza virus, para influenza virus, corona virus together cause as many as 15% of the respiratory tract infections.
Corona virus was first noticed in the stool of neo-nate and infants. They cause mild enteritis and colitis. Later on, they were detected in the lung tissues. The children suffered from broncheolitis and pneumonia. They reached the brain causing meningitis and encephalitis. In 1918, the notable pandemic, H1N1 came down killing more than 20 million people. There was a chain of pandemic which started in 2003 (Mexico & USA), next was in 2009 and then in 2019. Different strains came up causing SARS human corona virus. This led to the human surveillance with evidence of human population meaning they are comfortable with humans. In 2003, there was full cooperation between countries nearby. The transmission was through droplet containing the infective  organism with high morbidity and mortality.
Influenza virus are divided into A, B, C subtypes and A and B are human pathogens. Avian viruses have a complex epidemiology when avians and mammals are involved. They have 10 segments. H5N1 avian has shown that migratory birds can spread the disease. To put in a nutshell, the viruses are attracting themselves to humans as such they turn their eyes on mankind and probably is the beginning of a chain of pandemic observed. Let us go back to the chapter where we mentioned about the segments and strains.
Viral shedding is the episode where we can learn a lot. Normal duration is of 1 to 28 days and medium 3-6 days. Prolonged viral shedding gives:
1. Important knowledge about epidemiological control
2. Delayed viral therapy
3. Infection control measures.
In a retrospective study by Yinghu Chen in China, through clinical laboratory and radiological findings among children below 5yrs who had systemic diseases like heart, pulmonary blood dyscariasis, endocrinal kidney diseases, here the viral load was high. The risk factors for prolonged shedding in 2009 H1N1 influenza virus from 15th Nov-14th Dec, 2009 Children have longer pandemic viral shedding than adults due to delayed antiviral therapy. Male children below 5 years, Intensive Care Units patients and immunodeficiency patients. Influenza virus attracts sciatic acid and make its way to the vacuole causing lytic infection of epithelial cells of the respiratory tract. Then, the ciliary functions decreases. Subsequently, decreases mucous production thereby causing desquamation of the epithelial layer. There are 10 segments which ultimately is the cause of secondary bacterial infection and prolonged shedding. People who are transiently positive after sometime become negative and then become positive in the same patient. It may be due to secondary infection causing more complications. Further study is needed and suggested that viral shedding could be an important factor for control of corona virus.
How dreadful the microorganisms are even among old friends, H1N1. The risk factor attracts frequency 35-40% with children below 5yrs suffering from systemic illness, history of asthma, neurological diseases, blood dyscariasis, heart diseases. These four cases interestingly after 1 or 2 negative results test positive for 1 or 2 days. But all of them develop complications. Lastly further studies on viral shedding-viral replication would hopefully increase our knowledge of corona virus. Mixed epidemiology with avians, swines and mammals are only inviting complex epidemiology which is shown by previous pandemic needs further thoughts. The novel virus H1N1 transiently turn positive after being negative, this shows discontinuation of shedding and invites co-bacterial infection. The author is Senior Consultant (Pediatrician Retd.)