Diagnosis of HAT today
There has been a dramatic fall in the number
of cases of sleeping sickness over
the recent past, from an estimated 300,000
to 500,000 between 1998-2000 to less than
70,000 in 2006, giving a clear indication that
with improved or better tools for case detection
and management, the disease can be
eliminated.
Diagnosis of HAT is usually performed in two
steps: clinical suspicion or serological screening
on the one hand and confirmation plus
stage determination on the other. Both of the
steps are cumbersome, costly and in need of
improvement. Despite promising results from
initial evaluations of other tests, the Card
Agglutination Trypanosomiasis Test (CATT)
is still the reference serological screening assay
for T.b. gambiense. There is no equivalent test
for screening T.b. rhodesiense, which relies on
clinical symptoms and signs; indicators that
are far from satisfactory.
Other methods, such as immunofluorescence
and ELISA-based serological tests have variable
sensitivity, and can only be performed in
reference centers by well trained staff. The
characteristics of existing serological tests are
therefore insufficient to ascertain diagnostic
results.
“I had been complaining
of swollen
legs, headaches and
coughing for three
months”.This picture
was taken on
the day the patient
was diagnosed with
T.b. rhodesiense.
With early
and accurate diagnostics,
she will be
able to get proper
and safer treatment
in time.
Parasites have to be demonstrated in blood or
lymph node aspirates by microscopy to confirm
a diagnosis before staging can be done and
treatment started.
Staging of cases involves a series of tests on a
patient to determine whether parasites have
penetrated the CNS. A painful and invasive
lumbar puncture has to be performed, followed
by examination of the cerebrospinal fluid (CSF)
for parasites and concentration of white cells.
Screening, diagnosis and treatment are
mainly performed by national programs with
the aid of specialized, non-governmental
organizations or institutions. In order to
improve performance of the programs and the
sustainability of HAT control, two new tests
are needed:
■ A test to detect either T.b. gambiense or
T.b. rhodesiense, which is simple enough
to be used at point of care in remote
locations, and specific enough to direct
treatment in screening programs
among at-risk populations
■ A simple, preferably non-invasive staging test
to determine whether the CNS is affected
Better diagnostic tools will revolutionize HAT
control, improving mass screening and making
the introduction of HAT diagnostics in
peripheral health units located in remote and
rural areas a realistic goal. FIND, in partnership
with international and national organizations,
industry and academia, is facilitating
the development of such tests, to be made
widely available in sufficient quantities to
meet demand in high-burden countries at
affordable, or at least preferential, prices.
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