|
|
 |
[08/03/2005]
 Sierra Leone | |
|
Author: Dr Francis Louis, Yaounde, Cameroon
| |
General Statistics
Area: 71,620 km²
Population of the Archipelago: 4,400,000
inhabitants
Capital: Freetown
Currency: leone
Official Language: English
Bordering Countries: Guinea, Liberia
Out of 192 countries, Sierra Leone ranks 192nd for life expectancy,
192nd for infant mortality, 187th for GNP, 185th for daily calorie
intake, 184th for literacy, 161st for the percentage of children in
full-time education (source: Atlas Encyclopédique Mondial, Nathan
Ed., Paris 1996, pp.516-517).
| Epidemiological Facies
The climate in Sierra Leone is tropical and humid with a long rainy
season from May to December and a short dry season from December to
May. The temperature stays almost always the same, varying only
from an average of 22°C from July to September to 31°C from March
to May.
Given these conditions, malaria here is stable and
equatorial, according to Mouchet et al.’s classification:
The transmission via anopheles is intense and permanent and can
reach 1,000 infectious bites (anopheles females being sporozoïte
carriers) per person per year. This however allows for early
relative immunity, acquired by the age of 5. 30% - 50% of childhood
fevers are caused by malaria. Morbidity exists all year round.
Severe forms of the disease , especially pernicious malaria are
frequent in small children but rare in adults since they are
relatively immune. (14).
In the XVIII century, the country was nicknamed « White Man's Grave
» which shows the fatal extent to which malaria raged through the
non-immune white populations living there (12).
A 1969 study showed that malaria was responsible for 23% deaths in
children aged under 10 years old (1). Malaria is the primary cause
for low birth weight (3).
A 1992 study on 800 children aged from 0 to 7 years old showed
a Plasmodium falciparum carrier rate of 61%. This
rate was at 12% for Plasmodium malariae and 1%
for Plasmodium ovale (11).
A 1994, study conducted by A.A. Gbakima showed a parasite infection
rate of 42.6% for 1,106 inhabitants of 5 villages of a rice
producing region. Plasmodium falciparum represented
90.4% of isolated strains, Plasmodium malariae
2.1%, Plasmodium ovale 0.5% and mixed infections 7%
(21).
| Vectors
Anopheles gambiae is the principal malaria vector in
Sierra Leone (12). During a series of captures conducted from
January 1990 to April 1991, M.J. Bockarie et al.
identified Anopheles melas as the main vector in
Freetown and Anopheles gambiae and Anopheles funestus
in the Provinces. The numbers of anopheles captured is shown in the
table below (12):
Species of Anopheles captured in rural Sierra Leone from 1990 to
1991 Species captured | Numbers captured | | Anopheles gambiae s.s | 2524 | | Anopheles funestus | 218 | | Anopheles hancocki | 39 | | Anopheles coustani | 1 | | Anopheles obscurus | 1 | | Anopheles ziemanni | 17 | | Anopheles flavicosta | 3 | | Anopheles barberellus | 4 | | Anopheles marshalli | 3 |
Jacques Brunhes et al. (Les anophèles de la région afro-tropicale,
logiciel ORSTOM Ed., 1998) registered 23 different species of
anopheles in the country: Anopheles barberellus, Anopheles
brohieri, Anopheles brunnipes, Anopheles coustani, Anopheles
domicola, Anopheles flavicosta, Anopheles freetownensis, Anopheles
funestus, Anopheles gambiae, Anopheles hancocki, Anopheles
hargreavesi, Anopheles marshallii, Anopheles melas, Anopheles nili,
Anopheles obscurus, Anopheles paludis, Anopheles pharoensis,
Anopheles rhodesiensis rhodesiensis, Anopheles rufipes rufipes,
Anopheles smithii, Anopheles somalicus, Anopheles squamosus and
Anopheles ziemanni. | Chemoresistance
1. Resistance to chloroquine
The first cases of resistance were reported in January
1989, in 9 Americans who had spent time in Sierra Leone (5). A 10th
case was reported in March 1989 (4), and an eleventh in April (
7).
No in vivo or in vitro study has since been published.
2. Resistance to other antimalarial drugs:
In 1989 malaria was reported in a patient taking mefloquine. A
treatment with halofantrine also failed, and the patient was
finally cured by using chloroquine (6).
In May 1989 a second case of halofantrine resistance was reported
in a European who suffered a malaria attack whilst undergoing a
prophylaxis treatment with chloroquine (7).
In a retrospective study conducted between 1988 and 1990, Raccurt
reported 4 chemoprophylaxis failures with mefloquine
(8).
In December 1989, a chloroquine-resistant malaria was also shown to
be ciprofloxacine-resistant. A treatment with Fansidar® finally
cured the patient ( 9).
In 1996, 5 cases of malaria were reported in non-immune patients
who were incorrectly taking a chemoprophylaxis by cyclines
(27).
| The National Anti-Malaria Program
Virtually nothing has been published on this subject in Sierra
Leone.
For the period 1996-1997, Y. Kassankogno describes a program for
the training of 145 people in the treatment of serious cases of
malaria, but without any concrete results. He also mentions a case
management program and the use of treated mosquito nets without
further precision (30).
| Research Institutions
Not documented.
| Advice to travelers
According to the B.E.H. n°24-25 of 14th June 2005, Sierra Leone is
classified under chloroquine-resistance group III .This signifies
that a traveler spending less than 3 months in this
"chloroquine-resistance zone” should take the Mefloquine or
the Atovaquone-Proguanil combined treatment.
Individual measures of protection against insect bites should not
be forgotten: insect repellant skin cream, insecticide diffusers,
mosquito nets treated with long lasting insecticide.
| Bibliography
1. WILKINSON J.L. - Children in hospital in Sierra Leone: a survey
of 10,000 admissions. Trans. R. Soc. Trop. Med. Hyg. 1969 ; 63:
263-269.
2. TEKLEHAIMANOT A., COLLINS W.E., NGUYEN-DINH P. et Coll. -
Characterization of Plasmodium
falciparum cloned lines with respect to gametocyte production in
vitro, infectivity to Anopheles mosquitoes, and transmission to
Aotus monkeys. Trans. R. Soc. Trop. Med. Hyg. 1987 ; 81:
885-887.
3. AITKEN I.W. - Determinants of low birthweight among the Mendi of
Sierra Leone: implications for medical and socio-economic
strategies. Int. J. Gynecol. Obstetr. 1990 ; 33:
103-109.
4. BOUREE P., LE BRAS J., RINGWALD P. - Extension de la
chimiorésistance en Afrique de l'Ouest: premiers cas en Sierra
Leone. B.E.H. 1989 ; n°25: 103.
5. LACKRITZ E.M., ADAMSON R., WILLIAMS S., ROOF R. - Cluster of
chloroquine-resistant Plasmodium
falciparum malaria cases among short-term travellers to Sierra
Leone. Trans. R. Soc. Trop. Med. Hyg. 1990 ; 84:
217-218.
6. FELIX R., GAY F., LYOGOUBI A. et Coll. - Résistance croisée à la
méfloquine et à l'halofantrine lors d'un paludisme
à Plasmodium falciparum contracté en
Sierra Leone. Bull. Soc. Path. Exot. 1990 ; 83: 43-45.
7. GAY F., BUSTOS D., CAUMES E. et Coll. - Insuffisance d'une cure
d'halofantrine sur un paludisme
à Plasmodium falciparum
chloroquinorésistant contracté en Sierra Leone. Ann. Med. Int. 1990
; 141: 493-494.
8. RACCURT C.R., DUMESTRE-TOULET V., ABRAHAM E. et Coll. - Failure
of falciparum malaria prophylaxis by mefloquine in travelers from
West Africa. Am. J. Trop. Med. Hyg. 1991 ; 45: 319-324.
9. STROMBERG A., BJORKMAN A. - Ciprofloxacin does not achieve
radical cure of Plasmodium
falciparum infection in Sierra Leone. Trans. R. Soc. Trop. Med.
Hyg. 1992 ; 86: 373.
10. AMIN A., HILL R.B., HORTON S.A.T.P. et Coll. - Immunization
coverage, infant morbidity and infant mortality in Freetown, Sierra
Leone. Soc. Sci. Med. 1992 ; 35: 851-856.
11. BARNISH G., MAUDE G.H., BOCKARIE M.J. et Coll. - The
epidemiology of malaria in Southern Sierra Leone. Parassitologia
1993 ; 35 suppl.: 1-4.
12. BOCKARIE M.J., SERVICE M.W., TOURE Y.T. et Coll. - The ecology
and behaviour of the forest form of Anopheles gambiae.
Parassitologia 1993 ; 35 suppl.: 5-8.
13. PETERSEN E., MARBIAH N.T., MAGBITI E. et Coll. - Controlled
trial of lambda-cyhalothrin impregnated bednets and Maloprim®
chemosuppression to control malaria in children living in a
holoendemic area of Sierra Leone, West Africa. Study desing and
preliminary results. Parassitologia 1993 ; 35 suppl.:
81-85.
14. MOUCHET J., CARNEVALE P., COOSEMANS M. et Coll. - Typologie du
paludisme en Afrique. Santé 1993 ; 3: 220-238.
15. BARNISH G., MAUDE G.H., BOCKARIE M.J. et Coll. - Malaria in a
rural area of Sierra Leone. I. Initial results. Ann. Trop. Med.
Parasitol. 1993 ; 87: 125-136.
16. BARNISH G., MAUDE G.H., BOCKARIE M.J. et Coll. - Malaria in a
rural area of Sierra Leone. II. Parasitological and related results
from pre- and post-rains clinical surveys. Ann. Trop. Med.
Parasitol. 1993 ; 87: 137-148.
17. BOCKARIE M.J., SERVICE M.W., BARNISH G. et Coll. - Malaria in a
rural area of Sierra Leone. III. Vector ecology and disease
transmission. Ann. Trop. Med. Parasitol. 1993 ; 87:
125-136.
18. PETERSEN E., MARBIAH N.T. - QBC® and thick blood films for
malaria diagnosis under field conditions. Trans. R. Soc. Trop. Med.
Hyg. 1994 ; 88: 416-417.
19. MORGAN H.G. - Placental malaria and low birthweight neonates in
urban Sierra Leone. Ann. Trop. Med. Parasitol. 1994 ; 88:
575-580.
20. AIKINS M.K., PICKERING H., GREENWOOD B.M. - Attitudes to
malaria, traditional practices and bednets (mosquito nets) as
vector control measures: a comparative study in five West African
countries. J. Trop. Med. Hyg. 1994 ; 97: 81-86.
21. GBAKIMA A.A. - Inland valley swamp rice development: malaria,
schistosomiasis, onchocerciasis in South Central Sierra Leone.
Public Health 1994 ; 108: 149-157.
22. BOCKARIE M.J., SERVICE M.W., BARNISH G., TOURE Y.T. - Vectorial
capacity and entomological inoculation rates of Anopheles gambiae
in a high rainfall forested area of southern Sierra Leone. Trop.
Med. Parasitol. 1995 ; 46: 164-171.
23. TODOROVIC N.M., STEFANOVIC M., TINAN B. et Coll. - Steroidal
geminal dihydroperoxides and 1,2,4,5-tetraoxanes: structure
determination and their antimalarial activity. Steroids 1996 ; 61:
688-696.
24. RUHUL A. - Immunization coverage and child mortality in two
rural districts of Sierra Leone. Soc. Sci. Med. 1996 ; 42:
1599-1604.
25. BOCKARIE M.J., ALEXANDER N., BOCKARIE F. et Coll. - The late
biting habit of parous Anopheles mosquitoes and pre-bedtime
exposure of humans to infective female mosquitoes. Trans. R. Soc.
Trop. Med. Hyg. 1996 ; 90: 23-25.26. DAVID K.P., MARBIAH N.T.,
LOVGREN P; et Coll. - Hyperpigmented dermal macules in children
following the administration of Maloprim® for malaria
chemoprophylaxis. Trans. R. Soc. Trop. Med. Hyg. 1997 ; 91:
204-208.
27. ORNDORFF G., HENDRICK B. - Five cases
of Plasmodium falciparum malaria in
active duty navy personnel participating in operation assured
response. Military Med. 1997 ; 162: 820-823.
28. MARBIAH N.T., PETERSEN E., DAVID K. et Coll. - A controlled
trial of lambda-cyalothrin-impregtnated bednets and/or
dapsone/pyrimethamine for malaria control in Sierra Leone. Am. J.
Trop. Med. Hyg. 1998 ; 58: 1-6.
29. BOCKARIE M.J., GBAKIMA A.A., BARNISH G. - It all began with
Ronals Ross: 100 years of malaria research and control in Sierra
Leone (1899-1999). Ann. Trop. Med. Parasitol. 1999 ; 93:
213-224.
30. KASSANKOGNO Y. - Aperçu sur le programme de lutte contre le
paludisme africain pour la période 1996-1997. Malaria and
Infectious Diseases in Africa 1999 ; n°9 bis: 52-61.
31. DURAND R., DI PIAZZA J.P., LONGUET C. et Coll. - Increased
incidence of cycloguanil resistance in malaria cases entering
France from Africa, determined as point mutations in the
parasites'dihydrofolate-reductase genes. Ann. Trop. Med. Parasitol.
1999 ; 93: 25-30.
|
|
|
|
Version française 
