Hantavirus cardiopulmonary syndrome
Differentials
Viral upper respiratory tract infection
SIGNS / SYMPTOMS
Sinus congestion, rhinorrhea.
Rhinorrhea and sinus congestion are not features of hantavirus infection.
INVESTIGATIONS
Clinical diagnosis.
Influenza
SIGNS / SYMPTOMS
Influenza is commonly associated with upper airway symptoms.
INVESTIGATIONS
Influenza antigen testing and respiratory virus cultures are positive for influenza.
Coronavirus disease 2019 (COVID-19)
SIGNS / SYMPTOMS
Important to consider current epidemiologic situation. May give history of unwell contacts.
INVESTIGATIONS
Real-time reverse transcription polymerase chain reaction (RT-PCR): positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA. Rapid antigen tests may also be used.
Mycoplasma pneumoniae pneumonia
SIGNS / SYMPTOMS
Dry, persistent cough. Bullous myringitis may be present.
Clinical response to appropriate antibiotic therapy.
INVESTIGATIONS
Serum cold agglutinins may be positive in Mycoplasma infection.
Chlamydia pneumoniae pneumonia
SIGNS / SYMPTOMS
Upper respiratory symptoms and gradual onset of the infection.
Clinical response to appropriate antibiotic therapy.
INVESTIGATIONS
Positive culture for C pneumoniae.
Serologic tests for C pneumoniae can be diagnostic.
Histoplasmosis
SIGNS / SYMPTOMS
Histoplasma capsulatum proliferates in soil contaminated with bird or bat droppings. Exposure is commonly associated with cave exploration, close proximity to chicken roosts, demolition, and excavation. High concentration aerosol inocula can cause a diffuse pneumonia.
May be clinically indistinguishable.
INVESTIGATIONS
Positive culture and antigen testing.
Coccidioidomycosis
SIGNS / SYMPTOMS
Fungal pneumonia caused by Coccidioides immitis may be clinically indistinguishable.
May have associated rash.
INVESTIGATIONS
Positive serology for coccidioidomycosis.
Leptospirosis
SIGNS / SYMPTOMS
Conjunctival suffusion, hepatic involvement, most commonly a self-limiting illness.
Clinical response to appropriate antibiotic therapy.
INVESTIGATIONS
Leptospirosis serologic testing positive.
Dengue fever
SIGNS / SYMPTOMS
Residence in/travel to dengue-endemic region.
Typical skin flushing/rash.
Arthralgia.
Respiratory symptoms are less common.
Cases of hantavirus cardiopulmonary syndrome (HCPS) have been misdiagnosed as dengue in endemic regions due to overlapping symptoms.[73]
INVESTIGATIONS
Reverse-transcription polymerase chain reaction (RT-PCR) is positive for dengue virus RNA.
Dengue nonstructural protein 1 (NSA) is positive.
Serology is positive for dengue antibodies.
Other viral hemorrhagic fevers
SIGNS / SYMPTOMS
Residence in/travel to endemic region for specific viral hemorrhagic fever.
Affects all systems. Visible signs of hemorrhage are more common.
INVESTIGATIONS
Reverse-transcription polymerase chain reaction (RT-PCR) for the specific virus is positive.
Psittacosis
SIGNS / SYMPTOMS
History of exposure to domesticated or commercially raised birds, mammals, and exotic imported birds.
Splenomegaly is occasionally present.
Clinical response to appropriate antibiotic therapy.
INVESTIGATIONS
The diagnosis may be made serologically from paired sera for psittacosis-antibodies.
Coxiella burnetii pneumonia
SIGNS / SYMPTOMS
Caused by Coxiella burnetii infection (commonly of livestock and domestic animals) and exposure to contaminated soil or dust.
May be clinically indistinguishable.
INVESTIGATIONS
Immunofluorescence assay (IFA) of infected tissue is positive.
Acute respiratory distress syndrome (ARDS)
SIGNS / SYMPTOMS
May be clinically indistinguishable.
INVESTIGATIONS
Both ARDS and hantavirus cardiopulmonary syndrome (HCPS) produce diffuse air space disease on chest x-ray. Experienced radiologists may be able to distinguish between the two syndromes after viewing serial x-rays.[74]
Myocardial infarction
SIGNS / SYMPTOMS
Distinguishable by lack of fever.
INVESTIGATIONS
ECG changes of acute ischemia, and elevated levels of troponin.
Bacterial sepsis
SIGNS / SYMPTOMS
May be clinically indistinguishable, but history and exam may reveal primary source of infection.
INVESTIGATIONS
Blood cultures are usually positive in bacterial sepsis.
Hemodynamic measurements demonstrate increased peripheral vascular resistance (PVR) with hantavirus infection versus decreased PVR in septic shock.
Plague
SIGNS / SYMPTOMS
High fevers, purple skin patches, vomiting, seizures, shock.
INVESTIGATIONS
Blood, urine, sputum, and fluid from buboes or other lesions to identify Yersinia pestis bacteria.
Chest x-ray will show patchy areas in the lungs in pneumonic plague.
Rickettsial disease
SIGNS / SYMPTOMS
Recent tick exposure; triad of fever, maculopapular or petechiae rash, and headache.
INVESTIGATIONS
Immunofluorescence assay (IFA) titer ≥1:64.
Serum electrolytes show low sodium and elevated BUN.
Pneumocystis jiroveci pneumonia
SIGNS / SYMPTOMS
History of prior Pneumocystis pneumonia, HIV-positive, oropharyngeal candidiasis, recurrent bacterial pneumonia, weight loss.
INVESTIGATIONS
Chest x-ray: bilateral symmetrical interstitial infiltrates.
Induced sputum: positive for Pneumocystis.
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