MORPHOLOGY OF CORONA VIRUS

• CORONA VIRUS : positive strand enveloped RNA virus that are important pathogens of mammals and birds.

• Cause enteric or respiratory tract infections in a variety of animals inc humans ,livestock and pets.

• Its genome is about 29.7 kb , which is one of the largest among RNA viruses.

• SARS is similar to other corona virus in that its genome expression starts with translation of 2 large orf 1a and 1b which are 2 poly proteins.

SIGNS AND SYMPTOMS

PATHOGENESIS• Infectious agent = severe acute respiratory virus.• Newly discovered corona virus• Corona v= group of viruses that have halo/crown

like appearance.• mild to moderate respiratory illness in humans

or respiratory,GI,liverand neurologic diseases in animals

• Sometimes rarely causes pneumonia especially in weak immune system.

• Can usually survive in environment for a couple of days.

• Mode of transmission- through cough and sneezes.

- close person to person contact.

Clinical findings

• Chest X ray findings

COMPLICATIONS

• As with any viral pneumonia, pulmonary decompensation is the most feared problem.

• Patients often require intubation which may results in sequelae such as; intensive care .. Infection from nosocomial pathogens, tension pneumothorax from ventillation at high peak pressures & non cardiogenic pulmonary oedema

INVESTIGATIONS• Selected investigations are intended to

determine the cause of the respiratory illness.

Test for viral, bacterial and other usual respiratory pathogens

Identify common pathogens circulating in the community which may be responsible for the illness

• CBC, DLC, AST, ALT, bilirubin, alkaline phosphatase, LDH, CPK, urea, creatinine, electrolytes

• other diagnostic tests as indicated by patients condition

• Respiratory samples: NP swab #1: rapid antigen detection for

respiratory viruses, viral cultures, viral PCR ETT aspirate or Auger suction: SARS investigation throat swab #1: Group A strep throat swab #2: Mycoplasma PCR • Blood for serology: 1. One clotted tube[5 cc] labelled “SARS

serology” • Stool:• For viral electron microscopy

DIAGNOSIS. Virus Detection• Virus isolation: inoculate

suitable cell culture with patient specimens

Antibody Detection

When infected by SARS-CoV antibodies (e.g. IgM and IgG) are produced / change in level

• Enzyme-linked immunosorbent assay (ELISA)

Immunofluorescence assay (IFA): Sample: patient serum

Method:Fix SARS-CoV-infected cells on microscope’s slide (patient

antibodiesalready bound to viral antigens)Immunofluorescent-labeled 2º antibodies

bind to human IgG/IgMSignificance:

positive result after 10 days of onset

of illness

CDC guidelines for Confirmatory testing

• Positive RT-PCR test results should be confirmed in a reference laboratory. Confirmatory testing is particularly important in areas with a low prevalence of SARS-CoV disease, where the positive predictive value of the assay is likely to be quite low. CDC will conduct confirmatory testing during the early phases of an outbreak.

Dr.T.V.Rao MD16

MANAGEMENT OF SARS• Antibiotics are ineffective as SARS is a viral

disease. Treatment of SARS so far has been largely supportive with antipyretics, supplemental oxygen and ventilatory support as needed.

• Suspected cases of SARS must be isolated, preferably in negative pressure rooms, with complete barrier nursing precautions taken for any necessary contact with these patients.

• There was initially anecdotal support for steroids and the antiviral drug ribavirin, but no published evidence has supported this therapy

• Loading dose of 33 mg/kg X 1 [max 2 grams/dose];

• followed 6 hours later by 16 mg/kg/dose q6h for 4

• days [max 1 gram/dose]

• followed 8 h later by 8mg/kg/dose q8h • [max 500 mg/dose] for 3 to 6 days depending

on • clinical course

PREVENTION AND CONTROL• Protect Healthcare Personnel During Aerosol-

Generating Procedures• Limit personnel to those essential for

performing procedure• Wear appropriate personal protective

equipment–Gowns and gloves– Sealed eye protection (i.e., goggles)–Respiratory protection device

Isolation and Quarantine the best options

SARS needs to be regarded as a particularly serious threat for several reasons. The disease has no vaccine and no treatment, forcing health authorities to resort to control tools dating back to the earliest days of empirical microbiology: isolation and quarantine

• No vaccine is available.

REFERENCES

• Textbook of microbiology-ananthanarayan and panikar

• Textbook of microbiology-baveja• Wikipedia• Lange microbiology

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