The incubation period, that is, the time interval from infection
with the virus to onset of symptoms is 2 to 21 days. Humans are not infectious
until they develop symptoms. First symptoms are the sudden onset of fever
fatigue, muscle pain, headache and sore throat. This is followed by vomiting,
diarrhoea, rash, symptoms of impaired kidney and liver function, and in some
cases, both internal and external bleeding (e.g. oozing from the gums, blood in
the stools). Laboratory findings include low white blood cell and platelet counts
and elevated liver enzymes.
Diagnosis
It can be difficult to distinguish EVD from other infectious
diseases such as malaria, typhoid fever and meningitis. Confirmation that
symptoms are caused by Ebola virus infection are made using the following
investigations:
- antibody-capture
enzyme-linked immunosorbent assay (ELISA)
- antigen-capture
detection tests
- serum
neutralization test
- reverse
transcriptase polymerase chain reaction (RT-PCR) assay
- electron
microscopy
- virus isolation
by cell culture.
Samples
from patients are an extreme biohazard risk; laboratory testing on
non-inactivated samples should be conducted under maximum biological
containment conditions.
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