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June
2006
 Interview with Dr. Joseph Ndung置
In May of this year, Dr.
Joseph Ndung置 joined FIND to head its new sleeping sickness
program. FIND痴 portfolio of poverty-related diseases is
growing rapidly, permitting FIND to contribute actively to
the reduction of disease and poverty.
For many years, Dr. Ndung置
worked with the Kenya Trypanosomiasis Research Institute (KETRI)
as a research officer, rising through the ranks to become
its Director from 1995 to 2004. He then left to fill the
post of Chief Research Officer with the Kenya Agricultural
Research Institute (KARI), where he was employed before
joining FIND.
Q:
Dr Ndung置, would you tell us about some of the
particulars surrounding African sleeping sickness?
A:
Well, sleeping sickness, or African
trypanosomiasis, is a vector-borne parasitic disease
affecting both animals and people, and is found in 36
countries in Africa. The protozoa, known as trypanosomes,
are transmitted to humans by tsetse flies which are only
found in Africa, and are predominant in vegetation by lakes,
rivers, gallery-forests and vast stretches of wooded
savannah.
Q:
What is the risk of infection?
A:
In the year 2000, over 60 million people were
considered to be at risk of infection. At the time, 40,000
new cases were being reported each year, a figure that was
considered to be an underestimate because very few people
were being screened. Even today, screening is not systematic
or widespread. As such, the total number of people carrying
the disease was estimated to be over 300,000 per year. This
is a pretty alarming statistic, since the disease, if left
untreated, is ultimately fatal, causing an agonizing death.
Q:
Which regions in Africa are especially prone
to the disease?
A:
The disease occurs in sub-Saharan Africa. There
is a regional distribution of the infecting parasite
species. This means that Trypanosoma brucei gambiense (or
T.b. gambiense), which is found in west and central Africa,
causes a chronic, but not necessarily benign, form of the
disease. A person can be infected for months and even years
without showing obvious symptoms. However, once the symptoms
do emerge, the disease is at an advanced stage.
The other type of parasite,
T.b. rhodesiense, gives rise to a much more virulent form
of the disease and is found in southern and eastern Africa.
The disease flourishes in poor, rural conditions where
people often cannot afford to pay for diagnosis, let alone
treatment. What's more, these areas are poorly covered by
the national health services.
The disease occurs in
discrete foci and has a tendency to flare up when it is
least expected. Because of its focal nature, outbreaks
rarely attract national attention until they have turned
into epidemics. So far, there have been only three major
epidemics over the last century and although the disease
virtually disappeared between 1960 and 1965, it reappeared
in endemic form in several foci over the last thirty years,
due to the fact that screening and surveillance were relaxed
after the earlier success in attempts at eradication.
Another worrisome concern is that any instability in a
sleeping sickness region (such as war or tribal crushes) is
a recipe for increased transmission and flare-up of the
disease. It is encouraging to know that order is being
restored today in many countries in which instability
resulted in serious epidemics.
Q:
Tell us about the problem of diagnosis. How difficult
is it?
A:
A few weeks after one is infected, symptoms
entail headaches, pains in the joints, itching, and bouts of
fever. The parasites, which have the ability to invade all
body organs, pass into the central nervous system, where
they cause damage leading to the neurological, or late,
stage of the disease. At this point, symptoms in the form of
confusion, sensory disturbances and poor coordination
appear. The sleep cycle becomes troubled, which is where the
disease gets its common name.
The methods used to make a laboratory diagnosis of sleeping
sickness are costly and cumbersome, and they are neither
sensitive nor specific enough. None of the tests have ever
been developed to the stage of being manufactured in an
industry setting. The clinical signs of sleeping sickness
are not specific to the disease, and therefore diagnosis
relies heavily on the observation of parasites in the blood
or lymph node fluid, by microscopy. While this is normally
not difficult in patients with acute T.b. rhodesiense
infection because the blood tends to have large numbers of
circulating parasites, it is extremely difficult in T.b.
gambiense patients and in chronic T.b.rhodesiense.
A method for concentrating
trypanosomes exists, but it is too demanding to be useful at
a peripheral clinic level. A trypanosome antibody detection
test, known as the card agglutination trypanosomiasis test
(CATT) is used widely for screening people in T.b. gambiense
areas. Its sensitivity, however, varies from region to
region, and it cannot be used to make a decision on whether
or not to treat a person without carrying out other tests.
Q:
What about treatment?
A:
At the moment, there are only a few drugs for
treatment, which are expensive and rather unsafe. If a
patient does not receive treatment before the onset of the
second stage of the disease, the neurological damage is
sometimes irreversible even after treatment is begun. In
recent years too, there has been an increasing risk of the
two forms of the disease overlapping, especially in Uganda
and the Republic of Tanzania. If this occurs, there would be
major problems in treating the early stage of the disease
since, although morphologically the parasites look the same
under a microscope, treatments are different for each form
of the disease.
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Joseph Ndung置
explains methods for tsetse control to dignitaries during
the 25th meeting of the International Scientific Council for
Trypanosomiasis and Tsetse Research and Control (ISCTRC)
conference held in Mombasa, Kenya from 27 September - 1
October 1999. Among the officials present were the Kenyan
Vice-President, Prof. George Saitoti (third from the right),
and (to his right) the Minister for Agriculture, Christopher
Mogere Obure |
Q:
What is the story about disease staging? Can you
elaborate?
A:
Even after parasites have been observed in the
blood, the actual stage of the disease has to be determined
by examining the cerebrospinal fluid (CSF). The procedure
for extracting CSF through a lumbar puncture is
uncomfortable and sometimes painful, depending on the
ability of the technician, and in patients who are not in
the advanced stage of the disease, it is difficult to
accurately determine at what phase of the development of the
disease they are in. A wrong decision could lead to wrong
treatment.
Q:
What difference can FIND make?
A:
Control of sleeping sickness, and its eventual
elimination, will depend heavily on the early and accurate
diagnosis of the disease, followed by effective treatment.
FIND will play a crucial role
in facilitating incremental development of diagnostic tests
that are currently available, serving to make them more
accurate, simpler to use, and cheap enough to be affordable
by national health services.
In addition, FIND will take
advantage of its vast experience with diagnostics for other
diseases, and its strategic linkages with industry and
academia, to develop new diagnostics and staging tests for
use at the peripheral health systems, where you find most of
the patients.
Q:
What about other strategic partners?
A:
The prospects for elimination cannot, of course,
be contemplated unless the magnitude of the disease is
known. In this regard, FIND, in collaboration with the World
Health Organization痴 CDS/NTD/IDM program, will play a
crucial role in facilitating incremental development of
diagnostic tests that are currently available. FIND, the WHO
and other stakeholders will work together to make them more
accurate, simpler to use, and cheap enough to utilize in
developing countries. At FIND we also plan to employ
available sponsorship methods to change the paradigm from
one in which the attitude has been an attempt at controlling
and living with the disease, to one of sustained control
aimed at disease elimination.
Related information:
The Special Programme for Research and Training in Tropical
Diseases (TDR): African trypanosomiasis
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