Differentials

SIGNS / SYMPTOMS
INVESTIGATIONS
SIGNS / SYMPTOMS

Residence in/travel to a country/area or territory with local transmission, or close contact with a confirmed or probable case of COVID-19, in the 14 days prior to symptom onset.

Signs and symptoms are similar so it may be difficult to differentiate between the conditions clinically.

The situation is evolving rapidly; see our COVID-19 topic for further information.

INVESTIGATIONS

Real-time reverse transcription polymerase chain reaction (RT-PCR): positive for SARS-CoV-2 RNA.

It is not possible to differentiate COVID-19 from other causes of pneumonia on chest imaging.

SIGNS / SYMPTOMS
INVESTIGATIONS
SIGNS / SYMPTOMS

In addition to cough and fever there may be pleuritic chest pain, dyspnoea, and sputum production that may be mucopurulent.

INVESTIGATIONS

CXR: common finding is a lobar consolidation.

Blood culture: positive for infecting organism.

Sputum culture: growth of infecting organism.

SIGNS / SYMPTOMS
INVESTIGATIONS
SIGNS / SYMPTOMS

Most common cause of lower respiratory tract infection in children <1 year.[99]

Also a significant and often unrecognised cause of lower respiratory tract infection in both older and immunosuppressed patients.[100]

Gives rise to upper and lower respiratory symptoms that peak in 3-5 days and resolve within 7-10 days.

Characterised by seasonal outbreaks. In the northern hemisphere, these usually occur from November to April, with a peak in January or February. In the southern hemisphere, wintertime outbreaks occur from May to September, with a peak in May, June, or July. In tropical and semi-tropical climates, the seasonal outbreaks are usually associated with the rainy season.[101]

INVESTIGATIONS

Rapid assays utilising antigen capture technology that can be performed in less than 30 minutes are now available. The sensitivity and specificity of most of these tests exceed 90%, and they are a mainstay of the diagnostic algorithm in most clinical laboratories, as the identification by culture can take from 4 days to 2 weeks.[102]

SIGNS / SYMPTOMS
INVESTIGATIONS
SIGNS / SYMPTOMS

An important respiratory pathogen in adults and children; the second most common cause, after RSV, of acute lower respiratory tract infections in infants and young children.[103]

In adults, generally causes mild upper respiratory tract infections, but can induce life-threatening lower respiratory tract infections in immunocompromised patients.[104]

The seasonal patterns of PIV infection in the US have changed over the past few decades. After 1962, PIV-1 and PIV-2 began to present in epidemics, and currently appear every 2 years in the autumn. In comparison, PIV-3 occurs in annual spring epidemics, whereas seasonal patterns of PIV-4 infections have been difficult to establish, since the disease is usually mild and the virus is difficult to detect. In developing and tropical countries, parainfluenza viruses do not show seasonal variations.[105]

INVESTIGATIONS

Culture of PIV from the nasopharynx or lower respiratory tract remains the definitive test for diagnosis.[106]

Rapid antigen detection by immunofluorescence and EIA is available, with reported sensitivities of 75% to 95%.[107]

Serological testing can also be performed, but is time-consuming.

Multiplex PCR assays have become available that permit detection of a number of respiratory viruses with reported sensitivities of 95% to 100%, with excellent specificity.[108]

Use of this content is subject to our disclaimer