Severe Acute Respiratory Distress Syndrome

The typical story is a patient who presents to the emergency department with fever, a cough, three to four days of malaise and mild shortness-of-breath (SOB). The patient may complain of mild pleuritic chest pain without nasal congestion and pharyngitis. Fever can be as high as 102.5 degrees F with temperatures to 101.4 degrees F. Conversational dyspnea might be obvious. Oxygen saturations can be impaired as evidenced by pulse oximetry. Chest X-rays usually demonstrate bilateral patchy air-space opacities.

Transmission of SARS is primarily through contact and large droplet (more than 5 microns and, therefore, likely to fall within 3 feet) spread of secretions. Contact with body fluids including respiratory secretions, vomitus, and stool may result in transmission of the virus. Transmission of SARS occurred most frequently in household contacts or at the hospital with infrequent occurrences of community spread. Routes of transmission for SARS include close contact (fomites, droplet, or direct contact), airborne spread (airplane, Amoy Gardens - a housing complex where a plume of SARS-contaminated virus arose from blocked sewage and was carried on air currents, and the fecal-oral route).

The incubation period the virus is from two to ten days, with most viral shedding (transmission) occurring at the tenth day after exposure.

Severity of illness may impact viral load and opportunity for transmission. Airborne (fine particulate aerosol spread of droplets smaller than 5 microns that may remain suspended in the air) transmission has occurred most commonly in the hospital setting in association with aerosol-generating procedures such as administration of nebulizer treatments and endotracheal intubation. Some have suggested the terminology of "opportunistic airborne infections" for those infections that usually cause disease outside the lung (eg, in the gastrointestinal tract), but may result in infection in distal airways if a fine-particle aerosol is generated by nebulizers or intubation. Because of the demonstrated airborne transmission of SARS and the risk of aerosol-generating procedures to healthcare workers (HCW), patients suspected of having SARS should be placed on airborne, in addition to, contact precautions.

Most patients with SARS did not transmit the virus to anyone else. However, a few patients spread the virus to more than 10 people, each. These patients were termed "super-spreaders." The explanation of the superspreading phenomenon is unclear. Most instances of superspreading occurred within the hospital through an unrecognized case or an aerosol-generating procedure. However, in some instances, only limited contact with patients was made. Further study is needed to determine whether superspreading events represent increased viral shedding in patients with advanced disease and comorbidities, lenient or late infection control, or alternative transmission routes.

No specific therapy against SARS-CoV is available at this time, though many therapeutic agents have been tried including: ribavirin and corticosteroids, lopinavir/ritonavir in patients, and interferon and monoclonal antibodies in in-vitro studies and an animal model. These regimens have not been tested in large randomized controlled trials and some medications have the potential for serious side effects.

It can be a multisystem infection, with viral gastritis, myocarditis and evidence of other systemic viral infection.

Infected usually improve after two weeks with supportive therapy. Mortality rates in the ten to twenty percentile range have been reported.