Scientific bulletin 317 - May 2009
© IRD / J-F Trape
R
© Univ. Med. / H. Lepidi
ecent research
conducted by a
joint IRD−Université de
la Méditerranée team
showed that nearly half
the children in Senegal
were carrying bacteria
of the species
Tropheryma whipplei.
Still insufficiently
known today, this microbe is the pathogen
of Whipple disease1, a
serious infection that
can affect all the
victim’s organs. Onset
is generally signalled by pain in joints
followed by chronic
diarrhoea, weight loss
and sometimes neurological consequences.
The researchers fear
that T. whipplei is a
pathogen that is emerging in Sub-Saharan
Africa. The high rate
of this bacterial contamination means that
Whipple disease is likely to become a major
public health problem
for these countries
in the coming years.
This investigation is a
first step towards the
detection and treatment of people who
have contracted the
disease.
Whipple disease:
an emerging infection in Africa?
44% of children aged from 2 to 10 years in the villages of Ndiop and Dielmo (photo above), in Senegal are contaminated by T. whipplei bacteria.Left: human intestinal epithelium infected by T. whipplei.
IRD researchers and their scientific
partners from the University de la Méditerranée recently discovered high
prevalence of the bacterium Tropheryma whipplei in faecal samples
from Senegalese children. It was
present in 44% of children aged from
2 to 10 years from two villages located
in the south-west of the country. These
results can probably be extrapolated to
rural areas in the rest of the country,
even to the whole of Sub-Saharan
Africa. Contamination occurs in early
infancy (under 2 years).
This pathogen could therefore be emergent in the developing countries and
is potentially a major threat to public
health. It can induce gastroenteritis and
various other infections, but it is especially responsible for Whipple disease,
a serious infection which can prove to
be fatal if left untreated.
Prevalence2 of T. whipplei in Senegal:
Analyses were made of faecal samples
from 150 healthy children, in an age
range from under 2 months to 10 years,
living in the villages of Ndiop and Dielmo
in south-west Senegal. Forty-four per
cent of the children between 2 and 10
years were tested positive, compared
with 37% of children in the 2 months to
2 years age range and 11% of babies
of under 8 months. These prevalence
levels are much higher than those observed in Europe, Asia or America. Indeed very few infants below 2 years of
age in the industrialized countries of
the North are carriers of this pathogen.
All the water samples tested from eight
wells supplying drinking water to the
two villages proved negative. Nevertheless, contamination through water
stored in canaris (earthenware water
containers) cannot be excluded. Transmission therefore would not occur only
through the faecal-oral route3. Complementary tests, particularly on the
presence of the bacteria in saliva, are
under way.
A widespread bacterium:
Until relatively recently scientists
thought that T. whipplei was rare.
However, studies have shown 1 to 11%
of adults in Europe to be carriers. And
many children between 2 and 4 years
hit by gastroenteritis bear the pathogen
in their faeces. In addition, this latest
study proves that nearly half the chil-
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Scientific bulletin 317 - May 2009
For futher information
CONTACT :
Jean-François TRAPE
Unité mixte de recherche sur
les maladies
infectieuses et tropicales émergentes (IRD, CNRS, Inserm,
Université de la Méditerranée)
Address :
IRD Dakar
Av. Georges Pompidou
X rue Wagane Diouf
BP 1386
18524 Dakar, Sénégal
Tél : (221) 33 849 35 82
Jean-Francois.Trape@ird.fr
REFERENCES :
Fenollar F., Trape J.-F., Bassene H., Sokhna C., Raoult
D. Tropheryma whipplei in
fecal samples from children,
Senegal, Emerging Infectious
Diseases, 15(6), 2009
DOI: 10.3201/eid1506.090182
KEY WORDS :
Whipple disease, bacterium,
children, Senegal
dren living in rural areas in Senegal,
even in Sub-Saharan Africa, may well
also be carriers.
A new strain of T. whipplei in Senegal:
The investigations revealed 10 new
genotypes of the pathogens, spread
among 3 independent groups. All
these are specific to Senegal, including a particular one common to the
two villages. Such propagation of a
specific genotype starting from the
same strain is the expression of human-to-human bacterial transmission.
A pathogenic bacterium: Information
about T. whipplei is still sparse. However, the bacterium is known to cause
gastroenteritis and other localized infections such as endocarditis (inflammation of the inner lining membrane
of the heart) or meningo-cephalitis
(inflammation of the brain tissue and
meninges). However, it is more particularly responsible for Whipple disease,
a serious chronic infection which is invariably fatal if no antibiotic treatment
is applied. Pain in joints, chronic diarrhoea, neurological consequences: the
disease can affect all organs.
However, not all people carrying the
bacteria contract Whipple disease.
Many of them are healthy and do not
develop any infection. Another point is
that Whipple disease seems mainly to
affect white men of about 50 years old.
Why then do some carriers of the pathogen contract the disease while others
manage to avoid it? The research team
considered that those developing the
disease would have a susceptibility to
T. whipplei, probably a genetic one.
Larger-scale research is now under
way in Senegal. The scientists expect
to find prevalence rates of a similar
magnitude as observed in Ndiop
and Dielmo. Given the high frequency of the pathogen, Whipple disease
could become an emerging disease
in Sub-Saharan Africa. These investigations bring ways of identifying subjects who have contracted the disease.
Gaëlle Courcoux - DIC
Translation - Nicholas Flay
1. Only 1000 cases of Whipple disease
have been reported up to now and the disease has hitherto been considered as
rare. The reported research shows that it is
potentially frequent in Sub-Saharan Africa.
2. The prevalence of a bacterium is the
number of persons contaminated in a population at a given moment. It is usually expressed as a percentage.
3. One theory would be that human-to-human
transmission occurs through the faecal-oral
route. Recent studies showed the presence
of T. whipplei in sewer wastewater. Moreover, 12 to 26% of people working in waste
water collection and drainage are healthy
carriers of the bacterium.
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The prevalence rate of the bacteria observed in the villages of Ndiop and Dielmo (photos above)
can likely be extrapolated to other rural areas of Senegal, even to Sub-Saharan Africa as a whole.
Gaëlle Courcoux, coordinator
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