Investigations
1st investigations to order
reverse transcription-polymerase chain reaction (RT-PCR)
Test
Should be ordered in all patients with suspected SAHFs while the patient is in isolation.[2][3][5][6][9]
Sensitive test in the context of a febrile patient.
May not be available in local regions of relevant affected countries. Reference laboratories should have access to appropriate primer sets.
Result
positive for Junin virus, Guanarito virus, Machupo virus, Chapare virus, or Sabia virus RNA
enzyme-linked immunosorbent assay (ELISA)
Test
Ordered where RT-PCR is unavailable.
Often negative until >1 week into symptoms. May be negative in fatal cases who fail to mount a humoral immune response.[2][3][5][6]
Some laboratories may opt to do ELISA in parallel with RT-PCR; however, it may need to be repeated at a later stage if done initially during the early symptomatic stage and results are negative.
Result
positive for IgM or IgG to Junin virus, Guanarito virus, or Machupo virus
Investigations to consider
malaria screen
Test
Should be undertaken in all patients with suspected SAHF to assist with differential diagnosis.
Co-infection with malaria has been reported in other viral haemorrhagic fevers and the incidence of malaria is currently increasing in parts of South America, particularly Venezuela.
Result
negative (positive if co-infected with malaria parasites)
blood culture
electrolytes and renal function
Test
Patients with diarrhoea and vomiting may have electrolyte derangement that needs correcting during management. Renal impairment is rare, but may occur in the context of severe dehydration, shock, or at the terminal stages of disease when multi-organ failure may develop.[4][5]
Result
may demonstrate electrolyte abnormalities in dehydration or kidney impairment in later stages of the disease.
liver function
coagulation screen
Test
Indicated in patients with haemorrhagic disease for monitoring of condition and treatment intervention.
The most common findings are a prolonged activated partial thromboplastin time (aPTT) and a raised fibrinogen.
Studies of clotting factors and prothrombin have revealed the pathology is not related to disseminated intravascular coagulation.[3]
Result
may demonstrate prolonged aPTT and raised fibrinogen in SAHF
lactate dehydrogenase
Test
Mild elevations in lactate have been described in Argentine haemorrhagic fever.[4]
Result
may be raised in SAHF
creatine phosphokinase
Test
Mild elevations in creatine phosphokinase have been described in Argentine haemorrhagic fever.[4]
Result
may be raised in SAHF
CXR
Test
Respiratory symptoms are uncommon in SAHF, although in the terminal stages patients may develop multi-organ failure.[5][6]
Indicated in patients with respiratory disease to identify potential differential diagnoses.
Consider if discussing escalation of care in SAHF with multi-organ failure.
Result
may demonstrate lung pathology or focus of infection
arterial blood gas
Test
In patients with severe disease, these parameters may be useful in determining need for escalation of care (e.g., intensive care with organ support).
Although intensive care has not been described in patients with SAHF, it is not contraindicated as long as it can be done safely and with optimal protection for healthcare staff.
Caution should be applied in obtaining an arterial blood gas in those with haemorrhagic symptoms.
Result
parameters may be deranged in later stages of SAHF
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