Investigations
1st investigations to order
reverse transcriptase polymerase chain reaction (RT-PCR)
Test
Should be ordered in all patients with suspected Marburg infection while the patient is in isolation.
Result
positive for Marburg virus RNA
malaria investigations
Test
Rapid diagnostic tests and Giemsa-stained thick and thin blood smears are the tests of choice for malaria screening.
A positive result does not rule out Marburg virus infection and the possibility of dual infection should be considered in all patients with appropriate historical or epidemiological risk factors.[23]
Result
negative (may be positive if dual infection)
Investigations to consider
serum electrolyte levels
Test
Hypokalaemia, due to vomiting and diarrhoea or acute kidney injury, was seen in approximately 50% of cases in the 1967 outbreak.[13] Hypocalcaemia has been associated with fatal infection.
Result
may be abnormal
serum creatinine and urea
Test
Elevated serum creatinine or urea and abnormal electrolytes may indicate acute kidney injury. This may be seen after a few days of infection and may represent acute tubular necrosis.[13]
Result
may be elevated
blood lactate
Test
Elevated lactate is a marker of tissue hypoperfusion and is an indicator of shock. It is useful in acutely ill patients with signs of sepsis to identify the degree of systemic hypoperfusion and to guide fluid resuscitation. Lactate-guided resuscitation has been used in the care of patients with Ebola.[31]
Result
variable
ABG
Test
Arterial or venous blood pH and bicarbonate are useful in acutely ill patients with signs of sepsis to identify the degree of systemic hypoperfusion and guide fluid resuscitation.[31]
Result
variable
FBC
Test
Decreasing platelet count and marked leukopenia can be seen in the initial stages of infection; however, this is not diagnostic.[12] This is often followed by neutrophil leukocytosis in the later stages of infection in patients who eventually recover, along with normalisation of thrombocytopenia. Leukocytosis may persist and show immature forms. Patients with severe disease may show a progressive decline in platelet count as a manifestation of disseminated intravascular coagulation (DIC). Decreased haemoglobin levels have been associated with bleeding in previous outbreaks.[13]
Result
thrombocytopenia, marked lymphopenia; decreased haemoglobin (if bleeding manifestations)
coagulation studies
Test
Prolonged prothrombin time (PT) or activated partial thromboplastin time (aPTT) is associated with more severe infection and bleeding manifestations such as disseminated intravascular coagulation (DIC).[13]
Result
prolonged PT or aPTT, elevated D-dimer level (if bleeding manifestations)
urinalysis
Test
Haematuria and proteinuria may be seen in severe disease. Oliguria that does not respond to fluid resuscitation is a poor prognostic sign.[13]
Result
may show haematuria or proteinuria
LFTs
Test
Both ALT and AST are usually elevated; however, AST may rise out of proportion to ALT, and this is more suggestive of systemic tissue damage rather than hepatocellular injury. Higher mean AST and AST:ALT ratio are associated with fatal infection.[25] Bilirubin, GGT, and ALP are often normal or slightly elevated. Highly elevated ALT with severe jaundice suggests an alternative diagnosis (e.g., viral hepatitis).[13]
Result
high AST:ALT ratio; bilirubin, GGT, and ALP may be slightly elevated
serum amylase level
Test
Elevated levels have been reported in several studies and indicate the presence of pancreatitis, an indicator of severe infection.[13]
Result
may be elevated
blood cultures
Test
Negative blood cultures may be helpful in ruling out bacterial sepsis or enteric fever. Blood should be collected for culture at baseline and/or at the time of the onset of gastrointestinal symptoms or other clinical deterioration. Based on experience with Ebola virus disease, it is recommended that all filovirus patients be treated with broad-spectrum antibiotics for possible gut bacteria translocation, regardless of blood culture results.[32]
Result
positive or negative
antigen-capture enzyme-linked immunosorbent assay (ELISA)
Test
A useful diagnostic test with high specificity for filovirus IgM or IgG; however, it is not universally available and was rarely used in the 2014 to 2016 West Africa Ebola virus disease outbreak. ELISA for Marburg virus IgM may be positive as early as days 4 to 7 of infection, IgM levels peak 1 to 2 weeks later, and disappear by 1 to 2 months after convalescence.[33] Positive IgM or RT-PCR result can be used to confirm the diagnosis of acute Marburg virus disease.
Result
positive for Marburg virus IgM or IgG
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