Evolution of a pandemic: Coronaviruses to COVID-19

Coronavirus is not an exclusive finding of 2020 though it has been projected as “Novel Coronavirus” (nCoV). The so called nCoV has been designated as etiological agent of “Coronavirus Disease-2019” (COVID-19) that took shape of pandemic with its epicenter at Wuhan City of Hubei Province of China. Bovine and avian Coronaviruses are known since 1976 and a lot of research has already been done on their structure and pathogenicity.

The well characterized members of coronavirus family are positive-stranded RNA viruses. Coronaviruses possess a single-stranded, non-segmented, polyadenylated infectious RNA genome. The size of viral particles (virions) vary from 80-120 nm in diameter. Nanometer (nm) is ultra-small unit of measurement of length. There are one billion (1000,000,000) nanometers in a meter. These viruses could only be revealed through Transmission Electron Microscope (TEM) or Scanning Electron Microscope (SEM). Coronaviruses have pleomorphic look due to 10-20 nm long surface peplomers. Coronaviruses can cause diarrhea, hepatitis and bronchitis in lower mammals and birds. Three species of coronavirus are known to cause hepatitis in mice and seven species of coronavirus are known to cause bronchitis in birds.

Species of coronaviruses are characterized on the bases of molecular weight of surface polypeptides (glycoproteins). The molecular weight of surface glycoproteins of coronaviruses could be ranging from 15,000 to 200,000. They possess a large genome of 5x10⁶ to 8x10⁶ molecular weight. Massive research work has been done on coronaviruses in various virology laboratories all over the world to ascertain their genomic structure.

In the year 2002 “Severe Acute Respiratory Syndrome (SARS) was caused in humans by avian coronavirus (SARS-CoV). The animal reservoir of this coronavirus was perhaps bats. The avian coronavirus spread to other animals like cats and first infected humans in the Guangdong Province of southern China in 2002. An epidemic of SARS-CoV affected 26 countries in 2002-2003 and >8000 cases were reported as per World Health Organization (WHO). The transmission of SARS-CoV is primarily from human to human in the second week of disease due to excretion of viruses in respiratory secretions. So, infection spreads trough droplets of nasal secretion.

The current pandemic with Coronavirus has deliberately been given new nomenclature due to its genomic distinction from SARS-CoV known earlier. This new type of coronavirus causing SARS is called 2019-nCoV.

Symptoms of disease:

Symptoms of COVID-19 are like influenza and include fever, headache, shivering (rigors), myalgia, malaise, cough and sometimes diarrhea also. Fever is most frequently reported symptom, but it may be absent in initial stage especially in elderly and immunocompromised patients.

Cough may be dry initially with shortness of breath. Fever and diarrhea may progress in second week of disease. Elderly and people with associated illnesses like diabetes, hypertension, heart disease or organ transplant, may need special care to protect themselves from COVID-19.

Personal protection measures:

There is no immuno-prophylaxis for nCoV as vaccines are still under development. Personal hygiene, exercise and protein rich diet and vitamin-C are key to avoid coronavirus infection. Fresh fruits or juices rich in vitamin-C, high protein diet, coffee drinks, frequent drinking of warm water could be of great help to keep away COVID-19.

Frequent washing of hands with soap and water. Hand sanitization, wearing of face mask and maintaining physical distance (social distance) of approximately 6 feet would be of great help to avoid 2019-nCoV.

The need of the hour is not to panic but to follow the instructions and guidelines issued by local and national health authorities.

Diagnostic criterion:

Real Time - Reverse Transcription - Polymerase Chain Reaction (Real Time RT-PCR) is the only specific investigation to ascertain 2019-nCoV infection. The Chinese authorities isolated a new type of coronavirus from patients of outbreak of pneumonia in Wuhan City during laboratory investigations on 7^th January 2020 and named it 2019-nCoV.  Nasopharyngeal or oropharyngeal swabs are taken from suspected persons and transported to Laboratories in specially constituted transportation medium.

The principle of RT-PCR detection method is based on ‘Fluorogenic 5’ Nucleage Assay’. During the PCR reaction, the DNA polymerase cleaves the probe at 5’ end and separates the reporter dye from quencher dye only when the probe hybridizes to the target DNA. This cleavage results in the fluorescent signal generated by the cleaved reporter dye, which is monitored almost Real-Time by PCR detection system.

Warnings:

1.      This assay needs to be carried out by skilled personnel only.

2.      Clinical samples should be treated as highly infectious and samples should be prepared in biosafe laminar flow hoods.

3.      Do not use the kit after its expiry date.

4.      Carry out the test as per global standard procedure only.

5.      Avoid repeated freezing and thawing of reagents.

Care and treatment of infected persons:

Infected patients should be managed as per conditions. Patients should be home quarantined or admitted to COVID-19 Hospitals, as per clinical assessment. Symptomatic treatment should be started immediately.  Every patient needs to be instructed to wear face mask and wash/sanitize his/her hands frequently and maintain physical distance from other family members and friends. Proper counselling needs to be provided to patients with adequate supply of diet recommended by nutritionist. Health professionals need to wear ‘personal protection equipment’ (PPE) with adequate sanitization to avoid any cross infection.

Enforcement measures by administration:

Lockdown of public transport, schools, colleges, universities, offices and places of worships may be needed to restrict community transmission and spread of COVID-19. Medical infrastructure needs to be upgraded efficiently for optimum treatment of COVID-19 patients. Thermal screening at Airports, Seaports, Railway Stations and Bus Terminals is the first and foremost step to identify persons carrying virus. Proper arrangements for compulsory quarantine for 14 days of suspects with infection.

 

Investigations should be done as per WHO guidelines for pandemic surveillance. Containment Zones with large number of COVID-19 patients should be put under strict surveillance to avoid community spread of the disease. Strict enforcement of health & hygiene-related discipline could save the citizens and the nation.

Happy New Year - 2018

Dr. CS Rayat wishes his Followers & Friends “A Very Happy & Prosperous New Year-2018”.

“May every ray of the Sun fill your life with Success and Ultimate Happiness in 2018”

CS Rayat

Post-operative Anemia: Modern Approach

Up to 90% of patients undergoing major surgery may develop post-operative anemia. The term anemia refers to low hemoglobin level. The level of hemoglobin (Hb) varies across different races and age but as per the World Health Organization (WHO), Hb value below 13.0 g/dl in adult males and below 12.0 g/dl in adult females (who are not pregnant) should be considered a cut-off level for a diagnosis of anemia.

The cause of post-operative anemia is intra-operative blood loss. Patients with normal pre-operative Hb levels have been found to be anemic during post-operative follow ups. It has been observed that patients undergo down regulation of intestinal absorption of iron along with impaired mobilization of iron from body stores. Oral iron therapy is not generally recommended to increase Hb levels in post-operative patients.

Intra-operative and post-operative allogenic blood transfusions are generally done to overcome the anemia. The modern approach to overcome the post-operative anemia recommends pre-operative iron supplementation. Intravenous or infusible iron solutions like iron-isomaltoside 1000 solution has reduced the need for intra-operative allogenic blood transfusions.

The patients undergoing major surgeries should undergo following investigations:

·         Hemogram (including reticulocyte count)

·         Serum iron, ferritin and transferrin saturation

·         Carbohydrate Reactive Protein (C.R.P.) to rule out and active inflammation

·         Serum B-12 and Folic Acid levels should also be worked out in elderly patients

Available literature supports intravenous iron formulations in elective and non-elective major surgeries in patients with suboptimal Hb and/or inflammatory disease. Surgeons have a focus on “patient blood management”. Intravenous infusion of iron improves Hb concentrations and hematological response quickly and replenishes the iron stores. Subsequently also reduces treatment cost by decreasing blood transfusions and related complications.

Happy New Year - 2015

Dr. CS Rayat wishes his Followers & Friends “A Very Happy & Prosperous New Year-2015”.

“May every ray of the Sun fill your life with Success and Ultimate Happiness in 2015”

CS Rayat

Management of Tuberculosis: Diagnostic Approach

Accurate and timely diagnosis of Tuberculosis (TB) is a prerequisite for the treatment and control of spread of infection to other family members of the patient and health professionals dealing with patients. In the recent past several advances in the diagnosis and management of Tuberculosis (TB) have come out. Tools and technology are of great help in understanding of pathogenesis, demonstration of Mycobacterium, drug sensitivity testing and evaluation of prophylaxis.

Tuberculosis is a major health problem requiring early management at diagnostic and treatment level to bring down the mortality rate. In the developing countries the current mortality rate is 1 death per 100,000 population. The global incidence rate of Tuberculosis (TB) reported in the year 2010 was 128/100,000/year. To sustain the control and elimination of Tuberculosis (TB) there is a need for efficient testing and treatment regimens.

Diagnosis of Tuberculosis (TB) has conventionally been relied upon sputum microscopy of Micobacterium tuberculosis (an Acid Fast Bacilli) by Ziehl-Neelsen Staining Technique. The technique is very specific but has a poor sensitivity (around 50%). More sensitive technique used for demonstrating Acid Fast Bacilli (AFB) is by culture on Lowenstein Jensen Medium. Isolation of mycobacteria by culture method is considered to be gold standard in-spite of being time consuming.

The scenario of multi drug resistant TB (MDR-TB) has given a challenge to biomedical scientists to develop new drugs and diagnostic methods. Advances in molecular techniques for the diagnosis of TB have revolutionized diagnostic approach to this public health problem. Various new diagnostic modalities are based on the DNA extraction from the mycobacterial isolates. The nucleotide sequences of DNA are amplified and multiplied millions of times by polymerase chain reaction (PCR) for comparative diagnosis through detection of amplified DNA.

The tests that detect Mycobacterium tuberculosis antigens in clinical specimens could provide rapid and direct evidence of infection. The major targeted antigen of Mycobacterium tuberculosis is Lipo-arabino-mannan (LAM). LAM is detected in the urine of patients suspected of having pulmonary TB (Tuberculosis of lungs) as well as extra-pulmonary TB (Tuberculosis of organs other than lungs).

Molecular Tests are very sensitive and specific for diagnosis of infection and monitoring of treatment as well as for evaluating drug resistance. Uniplex-PCR (single insertion sequence IS6110 of 38 kDa)) or Multiplex-PCR (for multiplex targeting like IS6110 and MPB 64) are of great help for detecting drug resistance. Multiplex-PCR is more sensitive than Uniplex-PCR. Multiplex-PCR is useful in early detection, species differentiation (Mycobacterium tuberculosis or Mycobacterium avium) and epidemiology.

Two Molecular Assays used for rapid diagnosis of a case of TB and drug-resistance testing are:  i) X-pert MTB/RIF, and ii) Line Probe Assay (LPA)

i)                    X-pert MTB/RIF: X-pert MTB/RIF detects Mycobacterium tuberculosis (MTB) and resistance to Rifampicin (RIF) using Real-Time PCR (RT-PCR) Assay by amplifying MTB-specific sequence of the rpoB gene (inherent of MTB genome) that is probed with molecular beacons for mutations within the RIF-resistance determining region. Diagnosis of TB can be determined within 2 hours from the sputum samples with minimal health hazard. X-pert MTB/RIF test has 99% sensitivity and 100% specificity.

ii)                  Line Probe Assay (LPA):  Rapid detection of anti-TB drug resistance by Mycobacterium tuberculosis is the need of the hour for effective treatment and management of patient care. Line Probe Assays have been developed for rapid detection of rifampicin resistance and/or MTB-DR (especially rifampicin in combination with isoniazid). The Line Probe Assay (LPA) employs the hybridization of labeled PCR products with oligonucleotide probe on a strip and reading by colorimeter. The genotype MTB-DRplus Assay also simultaneously detects specific mutations in the katG gene conforming high level isoniazid resistance as well as in the inhA gene conforming low level isoniazid resistance.

The Molecular Assays are labeled for use on isolates from solid and liquid culture as well as directly on sputum smear positive pulmonary specimens. Mycobacterium tuberculosis ‘strain typing’ is very important for the analysis of the spread of tuberculosis as well as for monitoring the evolution of antibiotic resistance. These assays are also used to assess the bacterial load for monitoring of anti-TB treatment (ATT).

Just click the following link to update your knowledge about Management of Tuberculosis through Therapeutic Approach: http://drugsense.blogspot.in/2014/06/management-of-tuberculosis-therapeutic.html