[afro-nets] Mosquito/Malaria Control (42)

[Charles Obonyo <CObonyo@kisian.mimcom.net>]

Mosquito/Malaria Control (42)
-----------------------------

-----Original Message-----
From: Omlin, Francois
Sent: Tuesday, September 27, 2005 7:18 AM
To: 'KeNaaM@amrefke.org'; 'afro-nets@healthnet.org'
Cc: 'jgithure@icipe.org'
Subject: RE: [afro-nets] Mosquito/Malaria Control (41)


Dear Dr. White,

Reading your opinion on malaria/vector control I would like to
add some important data based observations obtained over the
last 4 years in the highlands of W. Kenya:
(1) Larval habitats of malaria vectors can be localized and
classified according to their productivity of malaria mosquito
larvae, thus source reduction is possible.

(2) Not only seasonality but also the proximity of larval habi-
tats to nearby homesteads needs to be considered.

(3) Man-made larval habitats seem to take a key position within
the list of all habitats, particularly disturbed habitats (Carl-
son et al, 2004).

(4) Source reduction of malaria vectors through water-management
and environmental friendly larviciding are a realistic and cheap
approach by which the communities are getting involved and be-
come owner of both the problem and the intervention.

I would like to suggest that for proper malaria vector control
as a tool of malaria prevention we shouldn't consider one single
approach but rather put our complementary activities into an in-
tegrated framework. Not making competition but rather working
together and exchanging our data and strategies for obtaining
significantly reduced malaria prevalences in a given interven-
tion setup is my personal 'malaria philosophy'. We would be
happy to show you our integrated approach in Nyabondo of Nyando
district and in Kisii and Gucha districts, respectively. Please
let us know if you are interested in and what date/time would be
suitable for you.

Thank you.

With kind regards,

Francois X. Omlin
Environmental Management Programme Leader
ICIPE-Kisii
Mob +254-722 267507
mailto:fomlin@icipe.org AND mailto:fomlin@kisian.mimcom.net


-----Original Message-----
From: Chris White
Sent: Friday, September 23, 2005 4:12 PM
Subject: RE: [afro-nets] Mosquito/Malaria Control (41)

My response to an argument sent out through AFRO-NETS.
Chris

To Whom It May Concern

I'm afraid that the argument for adopting certain methods for
vector control currently in use in the USA to the sub-Saharan
Africa context is weak to say the least.

To understand the reasons for different approaches being used in
these settings one has to understand something of the ecology
and behaviour of various disease vector species (which differ
markedly both across and within these geographical ranges - in
terms of breeding site preferences, feeding location prefer-
ences, host species preferences, biting times, transmission ef-
ficiency, disease organisms carried and so on).

One should also remember that the main threat being addressed
through aerial spraying in the southern USA is that of yellow
fever (YF), dengue and west nile virus (WNV) - not malaria. Each
of the arbo-viruses listed are not actually carried by potential
human malaria vectors (in fact they are carried by an entirely
different Genus altogether - Aedes).

It is important to understand too that the predominant malaria
vector species in middle Africa - Anopheles gambiae s.s. (which
is widespread south of the Sahara and north of South Africa) can
easily breed in small, transient, rain-fed pools such as hoof
prints and tyre ruts, feeds mainly on human hosts and feeds and
rest indoors. Considering the sheer number of suitable breeding
sites in places such as Uganda and Tanzania for example and the
resulting vector population densities in such areas and the
housing conditions of the human host population, it soon becomes
very clear as to why vector control through larval site spraying
is both physically unrealistic and economically unsustainable. A
treated insecticide-treated net on the other hand can provide
protection for the users (2 or more people) for up to 5 years
and when significant coverage is achieved in any one community
actually result in a 'mass-killing' effect on the vector popula-
tion, resulting in a reduction in malaria transmission and sub-
sequent malaria-related morbidity for the community. Also, it is
important to realise that the human population in Africa is
largely rural (and frequently remote). The logistics involved in
getting millions of nets to these communities is difficult
enough (although significant strides are being made), but the
idea of spraying tiny pools of water every time it rains in
tropical areas is obviously ludicrous.

Some suggested further reading on this subject:

Essential Malariology by Warrell and Gilles (eds) - chapter 4,
the Anopheles vector (by M.W. Service and H. Townson)

The Biology of Disease Vectors by Beaty and Marquardt

Medical Entomology by M.W. Service


Chris White
Programme Leader - Malaria
African Medical & Research Foundation (HQ)
PO Box 00506-27691
Nairobi, Kenya
Tel: +254-20-699-3215 (direct line)
http://www.amref.org

AMREF - Winner of the Gates Award for Global Health 2005