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LYMPHATIC FILARIASIS IN MADAGASCAR: RECENT DATA FOR AN OLD DISEASE

Richard Speare Richard.Speare at jcu.edu.au
Wed Apr 30 19:02:34 EST 1997


The following update on lymphatic filariasis in Madagascar has just been
circulated on Lymfilariasis.  I thought subscribers to Parasitology may
also be interested.

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Regards

Rick Speare

Moderator Lymfilariasis
Department of Public Health and Tropical Medicine
James Cook University
Townsville
AUSTRALIA

Phone:	-61-(0)77-225700
Fax:	-61-(0)77-225788
email:	Richard.Speare at jcu.edu.au


---------- Forwarded message ----------
Date: Wed, 30 Apr 1997 16:23:43 +0300 (GMT+0300)
From: esterre at pasteur.pasteur.mg
To: lymfilariasis at jcu.edu.au

LYMPHATIC FILARIASIS IN MADAGASCAR: RECENT DATA FOR AN OLD DISEASE

   Bancroftian filariasis was initially introduced in the South- 
West Indian Ocean by human migrations and described in most of the 
islands since the beginning of the 19th century. Due to a 
Wuchereria bancrofti strain with a nocturnal periodicity (maximal 
density between 8 p.m. and 6h30 a.m.), it is mainly transmitted by 
Anopheles gambiae, A. arabiensis and A. funestus even if some 
culicids (Culex quinquefasciatus) have been identified as proven 
vectors (for example, the only one present in Seychelles and Chagos 
islands). Probably related to malaria vector control programs (as 
in La Reunion and Mauritius, since 1949) or specific chemo- 
prophylaxis with DEC (islamic Comoros islands) or both (Mayotte 
island: DDT pulverisations since 1977, DEC tested in 1981 and then 
regularly distributed since 1985: see Galtier et al., Bull. Soc. 
Path. Exot., 1987, 80: 826-833), the disease is progressively 
retreating since the beginning of the 20th century with the notable 
exception of the eastern coast of Madagascar. This aspect of 
historical epidemiology is reviewed in a recent paper (in French, 
like all the others references mentionned in this release) of 
Julvez and Mouchet (Bull. Soc. Pathol. Exot., 1994, 87:194-201). 

   Since the initial surveys of Brygoo ((1958: 20 to 37 p.cent of 
the population of the east coast (18.384 exams !) with 
microfilariema, but also 6.5 p.cent of inhabitants of Mahajanga 
region on the west coast)) followed by Prodhon (in 1972, confirming 
the existence of sporadic cases on the west coast: 9.2 p.cent of 
inhabitants of Mahajanga, mainly of Comorian origin) and Bruhnes 
(in 1975, who demonstrated the absence of the disease on the high 
plateaux due to climatic conditions), there was no recent 
information on this parasitic disease in Madagascar. The situation 
in a pilot village on the east malagasy coast was compared in 1954 
(prevalence: 39.6 p. cent, mean density: 1850 microfilaria/cubic 
mm) and in 1967 (prevalence: 49 p.cent, mean density: 1925 
microfilaria/cubic mm), after ten years of regular (two times a 
year) insecticide (DDT and HCH) pulverisations for malaria control. 
A DEC-based (6mg/kg one time a month during 7 months) control trial 
was tested on the 53 inhabitants and confirmed (prevalence: 3.7 
p.cent, mean density: 100 microfilaria/cubic mm), by comparison 
with a control village (Dodin et al., Arch. Inst. Pasteur 
Madagascar, 1968, 37: 17-24), the efficiency of the prophylactic 
policy still developped since 11 years in French Polynesia (Laigret 
et al., Bull. WHO, 1966, 34: 925-938).
 
   Two recent surveys in the litlle island of Sainte-Marie (Nosy 
Boraha), 6 kms from the east coast, and in 8 districts along the 
eastern region revealed a global prevalence of 7.7 p.cent and 23 
p.cent, respectively. The mean parasitic density ranged from 50 to 
150 microfilaria/cubic mm in Sainte-Marie (Rakotomalala et al., 
Arch. Inst. Pasteur Madagascar, 1995, 62: 124-127), and was about 
180 microfilaria/cubic mm on the east coast region (Champetier de 
Ribes, BIESP, Ministry of Health, 1996, 6).
With a sex ratio of about 1.3, men are more exposed to pathology 
including chronic morbidity (elephantiasis, hydrocoele). The 
prevalence rate of chronic morbidity was 2.3 p.cent in Sainte-Marie 
district and 7.3 p.cent on the costal region. In this last area, a 
survey in 5 supplementary medical districts is planned and will 
give a better idea of the global prevalence and associated 
morbidity.
 
   As ivermectin is presently not available on the local pharma- 
ceutical market, mass treatment with DEC (6mg/kg) during three 
consecutive years is the recommended strategy. This repetitive mass 
treatment has been launched in 1995 in Sainte-Marie, but the 
population of the eastern region will have to wait for available 
funds before having the benefit of such a control program. 


Dr. Gilles Champetier De Ribes, Service de Surveillance 
Epidemiologique, Ministry of Health (DLMT division), PO Box 460, 
Antananarivo 101, Madagascar 
E-mail: deribes at bow.dts.mg   	
and
Dr. Philippe Esterre, Head of Parasitology Unit, Institut Pasteur 
de Madagascar, PO Box 1274, Antananarivo 101, Madagascar 
E-mail: esterre at pasteur.pasteur.mg

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[This is a magnificent contribution from our colleagues from Madagascar. 
Many thanks for the time and effort involved in this update. Mod - Rick
Speare]




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