Severe Acute Respiratory Syndrome (SARS)

Introduction

Severe acute respiratory syndrome(SARS), is a contagious and sometimes fatal respiratory illness.

First detected in china in November 2002.

Etiology

A type of corona virus, SARS-CoV.

Risk factors for severe disease include an

• age of >50 years and
• comorbidities such as cardiovascular disease, diabetes, or hepatitis.
• Illness in pregnant women.

Epidemiology

1. Incubation period (2-7 day max 10 days); Persons recovered from SARS should be allowed in public for 10days after symptom control.
2. The natural reservoir of SARS-CoV appeared to be the horseshoe bat and semidomesticated animals such as the palm civet.
3. In most cases, however, the infection was transmitted from human to human.
4. The outbreak ceased in 2003; and no cases were reported in 2005–2009.

Transmission

The mechanisms of transmission of SARS are incompletely understood.

Spread may occur by aerosols and perhaps by the fecal-oral route.

Some ill individuals (“superspreaders”) appeared to be hyperinfectious and

were capable of transmitting infection to 10–40 contacts.

Pathophysiology

SARS-CoV infects cells of the respiratory tract via the angiotensin- converting enzyme 2 receptor.

Virus is also found in the bloodstream, in the urine, and (for up to 2 months) in the stool.

Virus persists in the respiratory tract for 2–3 weeks, and titers peak on ~ 10 days.

In the lungs there is hyaline membrane formation, desquamation of pneumocytes in alveolar spaces, and an interstitial infiltrate made up of lymphocytes and mononuclear cells.

Giant cells are frequently seen, and coronavirus particles have been detected in type II pneumocytes.

Clinical features

SARS often resembles pneumonia or influenza with following features

1. Fever: temperature of 100.4 F or higher may be with chills
2. Headache
3. General feeling of discomfort
4. Bodyache
5. Dry nonproductive cough.
6. Diarrhoea

It may progress to ARDS accompanied by multiorgan dysfunction.

Investigations

1. CBC: lymphopenia, (~ 50% of cases, mostly CD4+ T cells)

Total WBC normal or slightly low, and thrombocytopenia,

2. Elevated SGOT, SGPT, Creatine kinase, and lactate dehydrogenase
3. Chest x-rays: variety of infiltrates,

Patchy areas of consolidation in peripheral and lower lung fields—or

Interstitial infiltrates; which can progress to diffuse involvement.

4. A rapid diagnosis of SARS-CoV infection can be made by reverse-transcription PCR (RT-PCR) of respiratory tract samples and plasma early in illness and of urine and stool later on.
5. SARSCoV can also be grown into Vero E6 tissue culture cells.
6. Serum antibodies can be detected by ELISA or immunofluorescence,

Management

There is no specific therapy of established efficacy for SARS.

Although has frequently been used, it has little.

have also been widely used, but their benefit is unestablished.

Supportive care to maintain pulmonary and other organ-system functions remains the mainstay of therapy.

Complication

Case-fatality rates varied among outbreaks, with an overall figure of ∼9.5%

Precaution

1. Washing hands frequently with soap and water or using an alcohol based hand rub
2. Instead of touching the fce with hands a disposable tissue to rub eyes or nose should be used.
3. Wearing disposable gloves during contact with the patients body fluids or faeces. The gloves should be thrown away in safe place and hand washed thoroughly.
4. Wear a surgical mask when sharing the same room as a person with SARS.
5. Wearing glasses also give some protection.
6. Use soap and hot water to wash the silverware, towels, bedding and clothing.
7. Use a household disinfectant to clean any surfaces that may have been contaminated with sweat, saliva, mucus, vomit, urine
8. Follow all Precautions for at least 10 days after the person is symptom free,

Further reading

1. Davidson’s Principles & Practice of Medicine 22nd edition.
2. Harrison’s Principles of Internal Medicine 18th edition.
3. Guidelines for management of SARS, Dengue and Nipah virus management.