STVM-93 A. Gueye ’ Mb. Mbengue ’ Th. Dieye...
STVM-93
A. Gueye ’
Mb. Mbengue ’
Th. Dieye ’
A. Diouf ’
M. Seye ’
ICowdriosis in Senegal :
M.H. Seye I
some epidemiological aspects
GUEYE (A.), MBENGUE (Mb.), DIEYE (Th.), DIOUF (A.), SEYE
immune status is concerned, data are available for only
(M.), SEYE (M.H.). LCI cowdriose au %nCgal : quelques aspects tpidt-
few ecological zones (13).
miologiques. f&w &I,. M&l. I,&. PNJJ rrop., 1993, 46 (I-2) : 217-221
I.es resultats d’une etude sur I’abondance d’Amblyomma variegatum
This article records the abundance of the vector in the
dam des zones ecologiques differentes et des taux d’infection par
main geographical areas and the tick infection rate in the
Cow&ta ruminantium
darts les nymphes et les adultes de la tique de la
North Guinean zones; the seroprevalence in the Sudano-
zone nord-guineenne sont present&. En m&me temps la seroprevalen-
Sahelian, North Sudan and the hinterland of the North
ce a ete determinee. Selon cette etude, le vecteur est le plus frequent
dam la zone nord-guineenne, suivie par la zone sud-soudanienne et la
Guinean zones is also reported.
zone cotiere des Niayes. Ailleurs, les populations de la tique sont
absentes ou peu importantes. Le taux d’infection dam la zone nord-
guineenne est eleve : I,1 p. 100 au moins chez les tiques adultes et
7,g p. 100 chez Ies nymphes. La seroprevalence dans les zones nord-
soudanienne et soudano-sahelienne est tres hasse a I’interieur, tandis
MATERIAL AND METHODS
qu’elle est plus elevee proche de la rote.
Abundance of the vector
The distribution and the abundance of Amblyomma varie-
gafum have been established essentially by studies on
INTRODUCTION
the population dynamics of this species in different ecolo-
gical zones of Senegal, i.e. :
Since the 1970s the introduction of exotic dairy cattle of
- Sahelian zone : annual rainfall of 300 to 500 mm, grass-
high productivity in the Niayes ecological zone has
land type of vegetation ;
emphasized the importance of cowdriosis as the major
pathological constraint to the development of animal pro-
- Coastal region of the Niayes: annual rainfall of 400 to
duction (3). Further findings on the mortality of native
600 mm , grassland and palm trees (Elaeis guineensis) in
goats occurring periodically confirm also the role of this
clay soil depressions ;
disease (4).
- Sudano-Sahelian zone : annual rainfall of 500 to
The lack of reliable information on the epidemiology toge-
800 mm ; shrubby grassland ;
ther with the control of this infection as a major objective,
justify the ongoing research programme aiming to investi-
- North Sudan zone : annual rainfall of 800 to 1 000 mm ;
gate the most important parameters of the disease : the
grassland and woodland ;
vector, namely Amblyomma
van’egatum (Fabricius, 1794),
the agent and the immune status of the livestock.
- South Sudan zone : annual rainfall of 1 000 to 1 200 mm ;
woodland ;
The vector distribution has been established by previous
studies consisting in collecting ticks on cattle of different
- North Guinean zone : annual rainfall of 1200 to
ecological zones and on wildlife (7). Studies have been
1850 mm ; woodland and forest.
performed in the Niayes area to assess the importance of
the infection by Cowdria ruminanfium (12). As far as the
In each of these zones, apart from the coastal Niayes,
40 cattle, 40 sheep and 40 goats were subjected to a
monthly removal of all their body ticks. In the particular
case of the Niayes region, the study was limited to cattle
and goats since sheep do not graze on natural pastures.
To compare the abundance of A. variegafum in the diffe-
rent ecological zones, the level of cattle infestation by
1. lnstitut s&-&galais
de recherches agricoles (ISRA), Laboratoire
adult ticks is used as the criterion. In fact, the larvae and
national de I’Blevage
et de recherches v&&inaires (LNERV), BP
nymphs of this species may engorge on several types of
2057, Dakar Hann. SBnBgal.
hosts, particularly birds.
Revue Elev. Med. vet. hyS trop., 1993, 46 (l-2) : 217-221
217
A. Gueye Mb. Mbengue Th. Dieye A. diouf M. Seye M.H. Seye
Infection rate of Amblyomma vat-iegaium
Indirect immunofluorescence
in the North Guinean zone
The test was carried out as described by MARTINEZ et
During the rainy season of 1992, unfed adult ticks were
al. (15).
collected from cattle grazing in day time on natural pas-
tures. Unfed nymphs were collected according to the
The antigen suspension is thawed and diluted i/l00 in
same procedure.
PBS (pH 7.4), and a drop of 10 PI is deposited on each
spot of special slides for immunofluorescence. The slide
The adult ticks and nymphs were fed on rabbits for 4 to
is dried and then fixed in methanol. IO PI of serum (l/80
5 days. They were divided into groups of 3 ticks and
dilution) is deposited per spot. A positive and negative
ground, then suspended in PBS (pH 7.2). The suspension
control serum at the dilution of l/80 is applied to one spot
was centrifuged for 5 min at 500 rpm. The supernatant
each of each slide. The slide is incubated for 30 min in a
was injected into a sheep by the intravenous route. A total
moist chamber at room temperature. The slide is washed
of 30 sheep was used for each tick stage (nymphs and
for 10 min in PBS and an antibovine IgG conjugate dilu-
adults). The temperature of the sheep was recorded
ted l/100 in PBS with 0.01 % Evans blue is applied.
daily.
Slides are again kept in a humid atmosphere for 30 Win
All sheep originated from cowdriosis-free areas in
and washed in PBS, as previously.
Northern Senegal. If we assume that one infected tick
They are mounted with glycerol and examined under a
can transmit the infection to an inoculated sheep, the fol-
fluorescent microscope.
lowing formula can be applied :
IRo* = Number of tiks infected**
I__- x l 0 0
Total number of ground ticks infected
RESULTS
An infected sheep (showing hyperthermia) may die or
survive. In the latter case, it is challenged with blood
infected with Cowdria ruminantium originating from the
same area. If no reaction is observed, it is considered that
Abundance
the previous hyperthermia was caused by tick infection.
The data on tick collection are reported in table I. The
parasite burden caused by adult ticks during one year
(map 1) allows to define three levels of abundance deter-
Seroepidemiology
mined as follows :
In March 1992, blood was collected from animals living in
Range of data
the following ecological zones :
9,618 - 53 = 9,565.
- 451 cattle in the North Sudan zone ;
If we retain 3 classes corresponding to the 3 categories :
- 271 cattle in the hinterland of the North Guinean zone
not abundant, abundant and very abundant, the length of
(Kedougou) ;
the class is :
- 149 cattle in the hinterland of the Sudano-Sahelian zone ;
9,565 : 3 = 3,188.
- 354 cattle in the coastal area of the latter zone.
Therefore the superior limit of the first class is : 3,188 t
The sera collected were centrifuged at 3 000 rpm for
53 = 3,241
15 mn. The supernatant was dispensed in 2 ml tubes and
stored at -20°C.
not abundant : < 3,241
The second class interval is : [3,241-6,429] : abundant.
Antigen production
The third class interval is : very abundant : > 6,429.
A Senegalese strain of Cowdria ruminantium originating
from the Niayes area has been maintained in endothelial
For the different ecological zones we get the following
cells (1, 15). A suspension of elementary bodies and
classification :
morulae is stored at -20°C in 200 ~1 aliquots.
- not abundant : North Sudan and Sudano-Sahelian
zones ;
1
- abundant : Niayes and South Sudan zones ;
*
: If30 = Infection rate observed
** : Number of sheep infected
- very abundant : North Guinean zone.
218
STVM-93
TABLE I Ticks collected on cattle, sheep and goats.
--.____
__-__-
._____~
L = Larvae
N = Nymph
A = Adult tick
*Study done during 18 months
Adult ticks
One out of 30 inoculated sheep died; no other sheep sho-
wed hyperthermia. The infection rate is :
IRo=1/90x100=1.1%
Seroprevalence
The results are given in table II. The seropositivity is low
in the Sudano-Sahelian and North Sudan zones.
However, the prevalence is higher near the coastal area
of the Sudano-Sahelian zone.
TABLE II Ifa test results of cattle of different ecological
zones.
I
---____
Number of
Number of
sera
positives
/o positives 1
Infection rates
149
1 8
3 5 4
!! 107
Nymphs
Seven out of 30 inoculated sheeps contracted the infec-
North Sudan
451
3 1
‘ tion, 2 died, 5 recovered and did not react to a new inocu-
1
lation of infected blood. The observed infection rate is the
following :
271
J 92
IRo = 7/90 x 100 = 7.8 %
219
A. Gueye Mb. Mbengue Th. Dieye A. diouf M. Seye M.H. Seye
DISCUSSION
REFERENCES
The distribution and the abundance of A. variegafum in
I. BEZUIDENHOUT (J.D.). PATERSON (C.L.). BARNARD (B.J.H.) I/z
the different ecological zones correspond to the observa-
tions made by MOREL (16) on the normal habitat of the
species in West Africa. However this tick is not the most
2. CAMUS (E.). Contribution a I’etude t!pidemiologique de la cowdriose
important numerically, in comparison with the other spe-
(C’olvdritr rumirznrllium)
en Guadeloupe. Thkr Dot Sci.. O-say. Cniversitt?
de Paris Sud, 1987. 202 p.
cies connected with livestock in the South Sudan and
coastal Niayes zones (5, 9). In the latter regions,
3. GUEYE (A.), MBENGUE (Mb.). KEBE (B.). DIOUF (A.). Note spizoo-
Boophilus geigyi AESCHLIMANN
and MOREL, 1965 and
tiologique sur la cowdriosc bovine dans Its Niayes au SCn@l. &1,rir EIc>l,.
MPd. 1pl. Pnys twp., 19x2, 35 : 2 17-2 I9
B. decoloratus (KOCH, 1844) are numerically more
important. On the contrary, the species is definitely domi-
4. CUEYE (A. ), MBENGUE (Mb.). DIOUF (A.). Situation $izootiolo-
nant in the North Guinean zone (10).
gique actuellc d,e la cowdriose des pctits ruminants dans les Niayes du
S&~&l. RP~~ Elcv. Mc;o! \\Gt. f’cry.~ rrcp. 19X4. 37 : ‘6X-27 I.
The observed infection rates are based on a low number
5. GUEYE (A. ), MBENGUE (Mb.), DIOUF (A.). SEYE (M.). Tique,s et
of ticks and sheep and their statistical significance
h6moparasitoses du b&ail au S&tgal. I. La region des Ninyes. Recur E/r\\,.
remains to be assessed.
M&d. l$f. ftrys trap.. 1986,3Y : 381-393.
The high infection rate of ticks in the North Guinean zone
6. GUEYE (A.), CAMICAS (J-L.). DIOUF (A.). MBENGUE (Mb.).
Tiques $ hCmoparasitoses du k&nil au St!n@al. II. La region sah@licnne.
recalls the data recorded in the coastal Niayes. The infec-
Rrvur Hal. M&L I&. I’qx rrop., 1987. 40 : I 19-125.
tion rates of adult ticks are equivalent in these two areas.
On the other hand, nymphs are more infected in the
7. GUEYE (A.), CAMICAS (J-L.). Distribution Lies tiques du l&ail. bf :
kIevage et potentialit& pastorales sahblicnnes. Synthkes carlographiques.
Niayes. However the high infection rate of ticks in the
SCn@gal. Maisons-Alfort, France. IEMVT. CTA, 1989. p. 20.
coastal North Guinean zone and the abundance of the
vector may explain the very high prevalence of infection
8. GUEYE (A.), MBENGUE (Mb.), DIOUF (A.). Tiques et hC;n.>parasi-
found previously among cattle in this area. Concerning
loses du b&d1 au S&gal. III. La Lone nerd-soudnnienne. Rpl,rrr Ekl,. M&I.
vP1. Pays trap., 19X9, 42 : 4 I I-420.
the seroprevalence, the low positivity rates in the hinter-
land of the Sudano-Sahelian zone and the North Sudan
9. GUEYE (A.), MBENGUE (M.). DIOLJF (‘4.). Tiquek et hkmoparniitoscs
zone correspond with the scarcity of the vector. The coas-
du b&i1 au SCn~gal. IV. La zone sud-soudanicnne. Ke\\vp Elo,. .Q’kl. v/k
Pnys rrop., 1989, 42 : 5 17-528.
tal microclimate allows a larger population of this tick.
This fact explains the high prevalence in this site.
10. GUEYE (A.), MBENGUE (Mb.). DIOUF (A.). SONKO (VI. L.).
Tiques &t hkrloparasitea du bttail au Skkgal. V. La zone nerd-guiniennc.
The seropositivity of the Niayes and coastal North
RC\\UP E[Pv. MPd. vc’t. Ptrys trcy. (B paraitrc).
Guinean zones which reaches about 90 % is far higher
II. GUEYE (A.), MBENGUE (Mb.), DIOUF (A.). Tiques et hemoparasites
(13)
du b&tail au SCn@gal. VI. La %onc soudano-snhelienne. R~wc~ .&P,~. MPd.
vdt. Pay5 t/v/,. (i paraitre).
The serological cross reaction between Cowdria ruminan-
12. GUEYE (A.), MBENGUE (Mb.), DIOUF (A.). EpidCniiologie de la
tium and Ehrlichia bovis (2, 14) does not allow an easy
cowdriose au S6ntgal. I. etude de la transmission et du taux d’illfection
interpretation of the results obtained.
d’Ar,~hl~onvn~~ ~auiegc&rn (Fabricius, 1793) dltns la rkgion des Uiayes.
Revue &v. M{d. vPt. Pa?s fro)/,. (j pnrahre)
Nothwithstanding
the low prevalence of the infection in
the Sudano-Sahelian and North Sudan belt, no mortality
13. GUEYE (A.), MARTINEZ (D.), MBENGUE (Mh.), DIEYE (Th.),
DIOUF (A.). EpidCmiologie dc la cowdriosc au S&~gal. II. Rku!tats de
is recorded so far in cattle, even if the disease is recogni-
suivis sero.Cpidemiologique~. RPI’W E/r~s. MC%/. t@f. Prr!s tr-o[>. (?I paraitre).
zed in goats of this area.
14. LOGAN (L.), HOLLAND (C.J.), MEBUS (C.A.), RISTIC (M.).
Serological relationship between Cotvtlricr r-rrnfirzcrfltirrnz
and certain
Ehrlichic~. Vet. Rec.., 19X6, 119 : 4%4S9.
IS. MARTINEZ (D.), SWINKELS (J.), CAMUS (E.). JONGEJAN (F.).
ACKNOWLEDGEMENTS
Comparison of three antigens for the serodiagnosis or heartwater by indi-
rect fluorescent test. RL’~M~ &LX. MN. l+r. Pqy.s fwp., 1990, 43 : I S(p- I66
The authors are grateful to Dr D. MARTINEZ for his kind
16. MOREL (P.C.). Contribution b la connais\\unco de la distribution des
supply of the antigen and thank Pr G. UILENBERG and
tiqucs (Acariens, Ixodidae et Amblyommidae) en Afrique &hio:>ienne
continentale. Thbse Doct. Sci. nat., Fat. Sci. Orsay. liniv. Paris, 1969. 388
Dr 0. SYLLA for their comments on the manuscript.
p. (Anncxe cartographique, 62 cartes).
220
STVM-93
GUEYE (A.), MBENGUE (Mb.), DIEYE (Th.), DIOUF (A.), SEYE
GUEYE (A.), MBENGUE (Mb.), DIEYE (Th.), DIOUF (A.), SEYE
(M.), SEYE (M.H.). Cowdriosis in Senegal : some epidemiological
(M.), SEYE (M.H.). Aspec~os cpidemioldgioos de la cowdriosis en
aspects. Rrwe k’h. MPd. I&. Pays rrop., 1993, 46 ( l-2) : 2 17-22 I
Senegal. &VW klr~. M&l. \\@t. Puy.v fro/~., 1993, 46 (l-2) : 2 17-22 I
The results of a study on the abundance of Amblyommu variegutum in
Se describen 10s resultados de un estudio sobre la abundancia de
different ecological zones and of Cowdria rzzminantium infection rates
Amblyommu vuriegutum en diferentes zonas ecologicas, asi coma las
in nymphal and adult ticks of the North Guinean zones are given.
tasas de infeccidn de Corvdria rzzminantizzm,
tanto en garrapatas adul-
Joint research is also conducted on the evaluation of seroprevalence.
tas y coma en estadio ninfal, en diferentes zonas al norte de Guinea.
In this study, it appears that the vector is most important in the
Conjuntamente se IIev6 a cabo una evaluation de la seroprevalencia.
North Guinean zone, followed by the South Sudan and the coastal
Segun nuestros resultados, el vector es mas importante en la zona
Niayes zones. Elsewhere, the tick populations are not significant or
norte de Guinea, el sur de Sudan y las zonas costeras de Niayes. En el
absent. The infection rate in the North Guinean zone is high : 1.1 %
resto del territorio Ias poblaciones de garrapatas son minimas o
at least for adult ticks and 7.8 % for nymphs. The seroprevalence in
nulas. La tdsa de infeccicin, en la zond norte de Guinea es elevadd : al
the North Sudan and the Sudano-Sahelian zones is very low in the
menos 1.1 p. 100 para las garrapatas adultas y 7.8 p. 100 para las nin-
hinterland whereas the values are higher near the coast.
fas. La seroprevalencia es baja en las regiones internas de1 norte de
Sudan y en las zonas sudano-sahelinas, mientras clue en las zonas cos-
teras es mas elevada.
.
221
A. Gueye ’
Mb. Mbengue ’
Th. Dieye ’
A. Diouf ’
M. Seye ’
ICowdriosis in Senegal :
M.H. Seye I
some epidemiological aspects
GUEYE (A.), MBENGUE (Mb.), DIEYE (Th.), DIOUF (A.), SEYE
immune status is concerned, data are available for only
(M.), SEYE (M.H.). LCI cowdriose au %nCgal : quelques aspects tpidt-
few ecological zones (13).
miologiques. f&w &I,. M&l. I,&. PNJJ rrop., 1993, 46 (I-2) : 217-221
I.es resultats d’une etude sur I’abondance d’Amblyomma variegatum
This article records the abundance of the vector in the
dam des zones ecologiques differentes et des taux d’infection par
main geographical areas and the tick infection rate in the
Cow&ta ruminantium
darts les nymphes et les adultes de la tique de la
North Guinean zones; the seroprevalence in the Sudano-
zone nord-guineenne sont present&. En m&me temps la seroprevalen-
Sahelian, North Sudan and the hinterland of the North
ce a ete determinee. Selon cette etude, le vecteur est le plus frequent
dam la zone nord-guineenne, suivie par la zone sud-soudanienne et la
Guinean zones is also reported.
zone cotiere des Niayes. Ailleurs, les populations de la tique sont
absentes ou peu importantes. Le taux d’infection dam la zone nord-
guineenne est eleve : I,1 p. 100 au moins chez les tiques adultes et
7,g p. 100 chez Ies nymphes. La seroprevalence dans les zones nord-
soudanienne et soudano-sahelienne est tres hasse a I’interieur, tandis
MATERIAL AND METHODS
qu’elle est plus elevee proche de la rote.
Abundance of the vector
The distribution and the abundance of Amblyomma varie-
gafum have been established essentially by studies on
INTRODUCTION
the population dynamics of this species in different ecolo-
gical zones of Senegal, i.e. :
Since the 1970s the introduction of exotic dairy cattle of
- Sahelian zone : annual rainfall of 300 to 500 mm, grass-
high productivity in the Niayes ecological zone has
land type of vegetation ;
emphasized the importance of cowdriosis as the major
pathological constraint to the development of animal pro-
- Coastal region of the Niayes: annual rainfall of 400 to
duction (3). Further findings on the mortality of native
600 mm , grassland and palm trees (Elaeis guineensis) in
goats occurring periodically confirm also the role of this
clay soil depressions ;
disease (4).
- Sudano-Sahelian zone : annual rainfall of 500 to
The lack of reliable information on the epidemiology toge-
800 mm ; shrubby grassland ;
ther with the control of this infection as a major objective,
justify the ongoing research programme aiming to investi-
- North Sudan zone : annual rainfall of 800 to 1 000 mm ;
gate the most important parameters of the disease : the
grassland and woodland ;
vector, namely Amblyomma
van’egatum (Fabricius, 1794),
the agent and the immune status of the livestock.
- South Sudan zone : annual rainfall of 1 000 to 1 200 mm ;
woodland ;
The vector distribution has been established by previous
studies consisting in collecting ticks on cattle of different
- North Guinean zone : annual rainfall of 1200 to
ecological zones and on wildlife (7). Studies have been
1850 mm ; woodland and forest.
performed in the Niayes area to assess the importance of
the infection by Cowdria ruminanfium (12). As far as the
In each of these zones, apart from the coastal Niayes,
40 cattle, 40 sheep and 40 goats were subjected to a
monthly removal of all their body ticks. In the particular
case of the Niayes region, the study was limited to cattle
and goats since sheep do not graze on natural pastures.
To compare the abundance of A. variegafum in the diffe-
rent ecological zones, the level of cattle infestation by
1. lnstitut s&-&galais
de recherches agricoles (ISRA), Laboratoire
adult ticks is used as the criterion. In fact, the larvae and
national de I’Blevage
et de recherches v&&inaires (LNERV), BP
nymphs of this species may engorge on several types of
2057, Dakar Hann. SBnBgal.
hosts, particularly birds.
Revue Elev. Med. vet. hyS trop., 1993, 46 (l-2) : 217-221
217
A. Gueye Mb. Mbengue Th. Dieye A. diouf M. Seye M.H. Seye
Infection rate of Amblyomma vat-iegaium
Indirect immunofluorescence
in the North Guinean zone
The test was carried out as described by MARTINEZ et
During the rainy season of 1992, unfed adult ticks were
al. (15).
collected from cattle grazing in day time on natural pas-
tures. Unfed nymphs were collected according to the
The antigen suspension is thawed and diluted i/l00 in
same procedure.
PBS (pH 7.4), and a drop of 10 PI is deposited on each
spot of special slides for immunofluorescence. The slide
The adult ticks and nymphs were fed on rabbits for 4 to
is dried and then fixed in methanol. IO PI of serum (l/80
5 days. They were divided into groups of 3 ticks and
dilution) is deposited per spot. A positive and negative
ground, then suspended in PBS (pH 7.2). The suspension
control serum at the dilution of l/80 is applied to one spot
was centrifuged for 5 min at 500 rpm. The supernatant
each of each slide. The slide is incubated for 30 min in a
was injected into a sheep by the intravenous route. A total
moist chamber at room temperature. The slide is washed
of 30 sheep was used for each tick stage (nymphs and
for 10 min in PBS and an antibovine IgG conjugate dilu-
adults). The temperature of the sheep was recorded
ted l/100 in PBS with 0.01 % Evans blue is applied.
daily.
Slides are again kept in a humid atmosphere for 30 Win
All sheep originated from cowdriosis-free areas in
and washed in PBS, as previously.
Northern Senegal. If we assume that one infected tick
They are mounted with glycerol and examined under a
can transmit the infection to an inoculated sheep, the fol-
fluorescent microscope.
lowing formula can be applied :
IRo* = Number of tiks infected**
I__- x l 0 0
Total number of ground ticks infected
RESULTS
An infected sheep (showing hyperthermia) may die or
survive. In the latter case, it is challenged with blood
infected with Cowdria ruminantium originating from the
same area. If no reaction is observed, it is considered that
Abundance
the previous hyperthermia was caused by tick infection.
The data on tick collection are reported in table I. The
parasite burden caused by adult ticks during one year
(map 1) allows to define three levels of abundance deter-
Seroepidemiology
mined as follows :
In March 1992, blood was collected from animals living in
Range of data
the following ecological zones :
9,618 - 53 = 9,565.
- 451 cattle in the North Sudan zone ;
If we retain 3 classes corresponding to the 3 categories :
- 271 cattle in the hinterland of the North Guinean zone
not abundant, abundant and very abundant, the length of
(Kedougou) ;
the class is :
- 149 cattle in the hinterland of the Sudano-Sahelian zone ;
9,565 : 3 = 3,188.
- 354 cattle in the coastal area of the latter zone.
Therefore the superior limit of the first class is : 3,188 t
The sera collected were centrifuged at 3 000 rpm for
53 = 3,241
15 mn. The supernatant was dispensed in 2 ml tubes and
stored at -20°C.
not abundant : < 3,241
The second class interval is : [3,241-6,429] : abundant.
Antigen production
The third class interval is : very abundant : > 6,429.
A Senegalese strain of Cowdria ruminantium originating
from the Niayes area has been maintained in endothelial
For the different ecological zones we get the following
cells (1, 15). A suspension of elementary bodies and
classification :
morulae is stored at -20°C in 200 ~1 aliquots.
- not abundant : North Sudan and Sudano-Sahelian
zones ;
1
- abundant : Niayes and South Sudan zones ;
*
: If30 = Infection rate observed
** : Number of sheep infected
- very abundant : North Guinean zone.
218
STVM-93
TABLE I Ticks collected on cattle, sheep and goats.
--.____
__-__-
._____~
L = Larvae
N = Nymph
A = Adult tick
*Study done during 18 months
Adult ticks
One out of 30 inoculated sheep died; no other sheep sho-
wed hyperthermia. The infection rate is :
IRo=1/90x100=1.1%
Seroprevalence
The results are given in table II. The seropositivity is low
in the Sudano-Sahelian and North Sudan zones.
However, the prevalence is higher near the coastal area
of the Sudano-Sahelian zone.
TABLE II Ifa test results of cattle of different ecological
zones.
I
---____
Number of
Number of
sera
positives
/o positives 1
Infection rates
149
1 8
3 5 4
!! 107
Nymphs
Seven out of 30 inoculated sheeps contracted the infec-
North Sudan
451
3 1
‘ tion, 2 died, 5 recovered and did not react to a new inocu-
1
lation of infected blood. The observed infection rate is the
following :
271
J 92
IRo = 7/90 x 100 = 7.8 %
219
A. Gueye Mb. Mbengue Th. Dieye A. diouf M. Seye M.H. Seye
DISCUSSION
REFERENCES
The distribution and the abundance of A. variegafum in
I. BEZUIDENHOUT (J.D.). PATERSON (C.L.). BARNARD (B.J.H.) I/z
the different ecological zones correspond to the observa-
tions made by MOREL (16) on the normal habitat of the
species in West Africa. However this tick is not the most
2. CAMUS (E.). Contribution a I’etude t!pidemiologique de la cowdriose
important numerically, in comparison with the other spe-
(C’olvdritr rumirznrllium)
en Guadeloupe. Thkr Dot Sci.. O-say. Cniversitt?
de Paris Sud, 1987. 202 p.
cies connected with livestock in the South Sudan and
coastal Niayes zones (5, 9). In the latter regions,
3. GUEYE (A.), MBENGUE (Mb.). KEBE (B.). DIOUF (A.). Note spizoo-
Boophilus geigyi AESCHLIMANN
and MOREL, 1965 and
tiologique sur la cowdriosc bovine dans Its Niayes au SCn@l. &1,rir EIc>l,.
MPd. 1pl. Pnys twp., 19x2, 35 : 2 17-2 I9
B. decoloratus (KOCH, 1844) are numerically more
important. On the contrary, the species is definitely domi-
4. CUEYE (A. ), MBENGUE (Mb.). DIOUF (A.). Situation $izootiolo-
nant in the North Guinean zone (10).
gique actuellc d,e la cowdriose des pctits ruminants dans les Niayes du
S&~&l. RP~~ Elcv. Mc;o! \\Gt. f’cry.~ rrcp. 19X4. 37 : ‘6X-27 I.
The observed infection rates are based on a low number
5. GUEYE (A. ), MBENGUE (Mb.), DIOUF (A.). SEYE (M.). Tique,s et
of ticks and sheep and their statistical significance
h6moparasitoses du b&ail au S&tgal. I. La region des Ninyes. Recur E/r\\,.
remains to be assessed.
M&d. l$f. ftrys trap.. 1986,3Y : 381-393.
The high infection rate of ticks in the North Guinean zone
6. GUEYE (A.), CAMICAS (J-L.). DIOUF (A.). MBENGUE (Mb.).
Tiques $ hCmoparasitoses du k&nil au St!n@al. II. La region sah@licnne.
recalls the data recorded in the coastal Niayes. The infec-
Rrvur Hal. M&L I&. I’qx rrop., 1987. 40 : I 19-125.
tion rates of adult ticks are equivalent in these two areas.
On the other hand, nymphs are more infected in the
7. GUEYE (A.), CAMICAS (J-L.). Distribution Lies tiques du l&ail. bf :
kIevage et potentialit& pastorales sahblicnnes. Synthkes carlographiques.
Niayes. However the high infection rate of ticks in the
SCn@gal. Maisons-Alfort, France. IEMVT. CTA, 1989. p. 20.
coastal North Guinean zone and the abundance of the
vector may explain the very high prevalence of infection
8. GUEYE (A.), MBENGUE (Mb.), DIOUF (A.). Tiques et hC;n.>parasi-
found previously among cattle in this area. Concerning
loses du b&d1 au S&gal. III. La Lone nerd-soudnnienne. Rpl,rrr Ekl,. M&I.
vP1. Pays trap., 19X9, 42 : 4 I I-420.
the seroprevalence, the low positivity rates in the hinter-
land of the Sudano-Sahelian zone and the North Sudan
9. GUEYE (A.), MBENGUE (M.). DIOLJF (‘4.). Tiquek et hkmoparniitoscs
zone correspond with the scarcity of the vector. The coas-
du b&i1 au SCn~gal. IV. La zone sud-soudanicnne. Ke\\vp Elo,. .Q’kl. v/k
Pnys rrop., 1989, 42 : 5 17-528.
tal microclimate allows a larger population of this tick.
This fact explains the high prevalence in this site.
10. GUEYE (A.), MBENGUE (Mb.). DIOUF (A.). SONKO (VI. L.).
Tiques &t hkrloparasitea du bttail au Skkgal. V. La zone nerd-guiniennc.
The seropositivity of the Niayes and coastal North
RC\\UP E[Pv. MPd. vc’t. Ptrys trcy. (B paraitrc).
Guinean zones which reaches about 90 % is far higher
II. GUEYE (A.), MBENGUE (Mb.), DIOUF (A.). Tiques et hemoparasites
(13)
du b&tail au SCn@gal. VI. La %onc soudano-snhelienne. R~wc~ .&P,~. MPd.
vdt. Pay5 t/v/,. (i paraitre).
The serological cross reaction between Cowdria ruminan-
12. GUEYE (A.), MBENGUE (Mb.), DIOUF (A.). EpidCniiologie de la
tium and Ehrlichia bovis (2, 14) does not allow an easy
cowdriose au S6ntgal. I. etude de la transmission et du taux d’illfection
interpretation of the results obtained.
d’Ar,~hl~onvn~~ ~auiegc&rn (Fabricius, 1793) dltns la rkgion des Uiayes.
Revue &v. M{d. vPt. Pa?s fro)/,. (j pnrahre)
Nothwithstanding
the low prevalence of the infection in
the Sudano-Sahelian and North Sudan belt, no mortality
13. GUEYE (A.), MARTINEZ (D.), MBENGUE (Mh.), DIEYE (Th.),
DIOUF (A.). EpidCmiologie dc la cowdriosc au S&~gal. II. Rku!tats de
is recorded so far in cattle, even if the disease is recogni-
suivis sero.Cpidemiologique~. RPI’W E/r~s. MC%/. t@f. Prr!s tr-o[>. (?I paraitre).
zed in goats of this area.
14. LOGAN (L.), HOLLAND (C.J.), MEBUS (C.A.), RISTIC (M.).
Serological relationship between Cotvtlricr r-rrnfirzcrfltirrnz
and certain
Ehrlichic~. Vet. Rec.., 19X6, 119 : 4%4S9.
IS. MARTINEZ (D.), SWINKELS (J.), CAMUS (E.). JONGEJAN (F.).
ACKNOWLEDGEMENTS
Comparison of three antigens for the serodiagnosis or heartwater by indi-
rect fluorescent test. RL’~M~ &LX. MN. l+r. Pqy.s fwp., 1990, 43 : I S(p- I66
The authors are grateful to Dr D. MARTINEZ for his kind
16. MOREL (P.C.). Contribution b la connais\\unco de la distribution des
supply of the antigen and thank Pr G. UILENBERG and
tiqucs (Acariens, Ixodidae et Amblyommidae) en Afrique &hio:>ienne
continentale. Thbse Doct. Sci. nat., Fat. Sci. Orsay. liniv. Paris, 1969. 388
Dr 0. SYLLA for their comments on the manuscript.
p. (Anncxe cartographique, 62 cartes).
220
STVM-93
GUEYE (A.), MBENGUE (Mb.), DIEYE (Th.), DIOUF (A.), SEYE
GUEYE (A.), MBENGUE (Mb.), DIEYE (Th.), DIOUF (A.), SEYE
(M.), SEYE (M.H.). Cowdriosis in Senegal : some epidemiological
(M.), SEYE (M.H.). Aspec~os cpidemioldgioos de la cowdriosis en
aspects. Rrwe k’h. MPd. I&. Pays rrop., 1993, 46 ( l-2) : 2 17-22 I
Senegal. &VW klr~. M&l. \\@t. Puy.v fro/~., 1993, 46 (l-2) : 2 17-22 I
The results of a study on the abundance of Amblyommu variegutum in
Se describen 10s resultados de un estudio sobre la abundancia de
different ecological zones and of Cowdria rzzminantium infection rates
Amblyommu vuriegutum en diferentes zonas ecologicas, asi coma las
in nymphal and adult ticks of the North Guinean zones are given.
tasas de infeccidn de Corvdria rzzminantizzm,
tanto en garrapatas adul-
Joint research is also conducted on the evaluation of seroprevalence.
tas y coma en estadio ninfal, en diferentes zonas al norte de Guinea.
In this study, it appears that the vector is most important in the
Conjuntamente se IIev6 a cabo una evaluation de la seroprevalencia.
North Guinean zone, followed by the South Sudan and the coastal
Segun nuestros resultados, el vector es mas importante en la zona
Niayes zones. Elsewhere, the tick populations are not significant or
norte de Guinea, el sur de Sudan y las zonas costeras de Niayes. En el
absent. The infection rate in the North Guinean zone is high : 1.1 %
resto del territorio Ias poblaciones de garrapatas son minimas o
at least for adult ticks and 7.8 % for nymphs. The seroprevalence in
nulas. La tdsa de infeccicin, en la zond norte de Guinea es elevadd : al
the North Sudan and the Sudano-Sahelian zones is very low in the
menos 1.1 p. 100 para las garrapatas adultas y 7.8 p. 100 para las nin-
hinterland whereas the values are higher near the coast.
fas. La seroprevalencia es baja en las regiones internas de1 norte de
Sudan y en las zonas sudano-sahelinas, mientras clue en las zonas cos-
teras es mas elevada.
.
221