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[afro-nets] Petition for effective malaria control in Africa

Petition for effective malaria control in Africa

Open Letter to WHO on malaria control policies

Dr Lee Yong-wook
Director General
World Health Organisation
Avenue Appia 20
1211 Geneva 27, Switzerland

April 2004

We are a group of scientists, doctors and researchers who are
writing to you because of our deep concerns over the way in
which WHO is conducting Roll Back Malaria (RBM) and other ma-
laria control initiatives.

We feel that the WHO ignores the advice and research of many ma-
laria control scientists and specialists from around the globe
and supports malaria control initiatives based on political, and
not scientific, criteria. We object to the stance that the WHO
has taken against the use of insecticides in indoor residual
spraying (IRS) programmes. More specifically, we object to WHO
exerting political and financial pressure to force malaria en-
demic countries to reduce or not begin use of DDT for malaria
control. We object to the notion that is put forward by the WHO
that IRS programmes are unsuitable for most malaria endemic ar-
eas. IRS has proved extremely successful in lowering malaria
morbidity and mortality in the past and remains so in many parts
of the world. IRS is only unsustainable or unsuitable if coun-
tries and international organisations do not give it the re-
quired political, financial and scientific support. Where IRS
programmes receive such support, they lead to a sustained reduc-
tion in malaria transmission.

While we recognise the potential importance of insecticide
treated nets (ITNs) in malaria vector control programmes, their
use should not exclude the use of IRS, and countries and inter-
national organizations should not support the use of ITNs at the
expense of IRS.

We urge you to consider the points raised in our letter and to
act fully and promptly upon them.

Our concern with Roll Back Malaria (RBM) and our desire to see
significant changes in the way in which WHO conceives and con-
ducts ongoing RBM activities prompts this letter.

As the WHO and UNICEF's Africa Malaria Report 2003 acknowledges,
malaria is the biggest killer of young children and the most
significant health threat to pregnant women and newborns in the
developing world. As malaria scientists, we are well aware of
the appalling burden that malaria places on some of the world's
poorest and most vulnerable people, and we are concerned that
the RBM programme increases that burden by deliberately under-
mining one of the most effective tools against malaria, indoor
residual spraying (IRS). Not only does RBM not support the use
of this life saving tool, RBM also fails to fulfil its stated
objective of supporting the development of new insecticides for
IRS. Furthermore, we believe that by undermining vertical ma-
laria control programmes, RBM has undermined malaria control ef-
forts in many poor countries and has dissipated some important
human capital needed for malaria control.

Our concerns are not new. Malaria control experts have voiced
them over many years. From the late 1970s, through the 1980s and
1990s, malaria control strategies evolved primarily through po-
litical processes, not by consultation and deliberation with ma-
laria control experts. As a result, malaria has re-emerged and
is now a global public health disaster. As the malaria burden
increases in developing countries, the threat of malaria intro-
ductions in developed countries grows apace. For these reasons,
there is now a strong consensus among experts that WHO's malaria
control strategies are not appropriate and changes are neces-

We call on RBM to reverse its policy against the use of IRS .
Instead of undermining IRS use, RBM should actively promote it
and support those countries that wish to implement IRS pro-
grammes. We further call on RBM to form public-private partner-
ships to investigate and develop new insecticides for malaria
control and not to force countries to adopt horizontal malaria
control programmes.

Indoor Residual Spraying

Experts have long known that IRS is one of the most effective
ways of controlling malaria. IRS programmes eradicated malaria
from Europe and the United States and were dramatically success-
ful in many poor countries with endemic malaria, such as India,
Sri Lanka(1) and much of Southern Africa(2). The malaria eradi-
cation programme of the post war years showed that well coordi-
nated and focussed IRS can reduce the burden of the disease.

IRS remains a vital malaria control tool in many parts of Af-
rica, Asia and Latin America. For instance, South Africa has
successfully used IRS to keep malaria under control for more
than 50 years. South Africa is not alone in sustaining a well-
run IRS programme; Swaziland, Namibia, Zimbabwe and Botswana
have all run IRS programmes that have successfully controlled
the disease.

The WHO anti-IRS agenda

During the 1960s and 1970s, political opposition, mostly in ad-
vanced and malaria-free countries, began to rise to the use of
insecticides (particularly DDT) in agriculture and in disease
control. Although malaria experts such as us widely acknowledge
DDT as vitally important in saving lives, political organiza-
tions have applied significant pressure on countries to reduce
the use of DDT. The WHO has not been immune to such pressure.
Indeed its practices and positions have strengthened this po-
litical, life threatening agenda.

WHO's 1979 global strategy for malaria control called on coun-
tries to de-emphasize IRS and to increase emphasis on case de-
tection and treatment. In 1985, the World Health Assembly (WHA)
resolution 38.24 called on malaria-endemic countries to move
away from IRS and to dismantle the vertical malaria control pro-
grammes and move towards a more horizontal "community-based"
system of malaria control. The 1979 strategy and the WHA resolu-
tion effectively destroyed organized malaria control programs in
many developing countries. WHA resolution 38.24 caused a devas-
tating loss of talented malaria control personnel and a loss of
strict scientific guidance over malaria control programs. This
immensely destructive resolution was based on a false assumption
that a community-based system is the only framework within which
malaria control can be sustained. Acceptance of the resolution
ignored the fact that many highly successful and long lasting
malaria control programmes are run vertically and have been sus-
tained for decades.

Countries that chose not to decentralise their malaria control
activities and chose to retain IRS for malaria control have not
witnessed the rise in malaria cases experienced by those coun-
tries that complied with the WHO's resolution. In the early
1990s, Ecuador chose to increase its IRS programme with the use
of DDT and greatly reduced the number of its malaria cases while
the disease ravaged its neighbours. Mexico renewed its house
spray programme after 1985 and successfully used DDT to reduce
malaria rates. Mexico stopped using DDT in 2000 and turned to
heavy reliance on mass drug distribution (pharmaco-suppression),
raising the risk of growing drug resistance problems.

Despite the wealth of historic and contemporary data and scien-
tific evidence that supports IRS as the single most important
tool to fight malaria, RBM does not promote IRS in any meaning-
ful way. Official RBM documents that describe the work programme
almost exclusively mention ITNs as the preferred means of vector

The single-minded focus on ITNs contrasts sharply with the ongo-
ing and highly successful IRS programmes in several countries.
For instance, IRS programmes in Swaziland since the 1960s have
ensured an average of only 3,063 confirmed cases between 1981
and 2003, even though the Swaziland Department of Health esti-
mates that around 350,000 people are at risk from the dis-
ease(4). This vigilant and carefully controlled IRS programme
uses DDT and other insecticides and has ensured that Plasmodium
falciparum infections in Swaziland are very low. A baseline
study of children between the ages of 2 and 15 conducted in De-
cember 1999 found 4% parasite prevalence in Mlumeni, 2% in Lo-
mahasha and only 1% in Shewula. In neighbouring Mozambique, with
no IRS at that time and in that area, the parasite prevalence
for the equivalent age group at the same time ranged between 37%
at Namacha and 90% at Catuane(5).

In recent years the Konkola Copper Mines (KCM) launched a pri-
vately funded IRS programme in the Zambian Copperbelt, an area
that had had little malaria control since the early 1980s. The
IRS programme has achieved some outstanding and sustained re-
sults in malaria control, protecting all the residents in the
towns of Chingola and Chililabombwe. While this IRS program pri-
marily uses DDT, it also uses synthetic pyrethroid insecticides
on those structures that are not suitable for DDT spraying. In
its first year, the control program halved number of malaria
cases, and the success continues with dramatically lower morbid-
ity and mortality(6,7).

DDT remains highly effective in malaria control because of its
unique modes of action against mosquitoes. Efficient malaria
vectors move sequentially to houses, enter, bite humans indoors,
and after biting, exit the house to subsequently rest and lay
eggs. Indoor biting equates to efficient malaria transmission
because a mosquito that bites indoors will almost certainly bite
a human. Thus, indoors, the mosquito can more efficiently ac-
quire malaria infection or transmit infection to another human.
DDT on inner walls can prevent mosquitoes from entering the
house (a repellent action), or it can induce premature exiting
following brief physical contact indoors (an irritant action),
or, following prolonged contact, it can cause death (toxic ac-
tion). Interactions of DDT actions can be quantified by applying
the multiplication law of probabilities (1). If DDT prevents 50%
of malaria vectors from entering the house, then probability of
entering is 0.5 (i.e., 1-0.5). If DDT causes 50% of mosquitoes
that enter to exit prematurely without biting, then the condi-
tional probability of biting, once indoors, is 0.5. If DDT
causes death in 50% of biting mosquitoes indoors, then, the con-
ditional probability of surviving once entering and biting in-
doors is 0.5. Given these conditional probabilities, it becomes
apparent that the real power of DDT is the combination of repel-
lent, irritant, and toxic actions, not just its slow acting
toxic action. For example, the joint probability of entering and
biting is only 0.25 (or 0.5 X 0.5). So, 75% (1-(0.5 X 0.5)) of
indoor malaria risk will be eliminated through repellent and ir-
ritant actions alone, without benefit of chemical toxicity. In
fact, in this scenario, toxicity will act against only 12.5% of
the total indoor risk of malaria.

DDT's repellent action was documented as early as 1947 (2). Re-
cent studies show that DDT repellent actions can function at
levels of 90% effectiveness or greater (3). Furthermore, com-
puter simulations suggest that joint repellent and irritant ac-
tions below 30% effectiveness are required before toxicity be-
comes the primary mode of chemical action (4). In a comparison
of deltamethrin versus DDT on house walls, DDT provided much
higher protection because deltamethrin did not repel house-
entering mosquitoes (3). This test showed that irritant or kill-
ing actions alone may not prevent indoor biting; but repellent
actions can prevent mosquitoes from being indoors in the first

Further RBM failures

We believe that the RBM programme has failed to interpret the
Abuja Declaration fully. The Declaration, which was signed by
all African heads of state, clearly resolves that by 2005 "at
least 60% of those at risk from malaria, particularly pregnant
women and children under five years of age, benefit from the
most suitable combination of personal and community protective
measures." While the Declaration highlights the use of ITNs, it
specifically does not exclude other forms of vector control such
as IRS. Indeed the Declaration specifically calls for "other in-
terventions, which are accessible and affordable to prevent in-
fection and suffering(8)."

Despite the clear call from African heads of state that Roll
Back Malaria should include methods of vector control other than
just ITNs, RBM remains largely focussed on this method of con-
trol and actively works to get countries to stop using IRS. No-
where is this more apparent than in the Africa Malaria Report
2003 (AMR 2003) published by WHO and UNICEF, two of the RBM

The AMR 2003 acknowledges that "Indoor residual spraying can
play an important role in malaria vector control, especially in
the control of epidemics(9)." The report also acknowledges that
some southern African countries use IRS and goes on to recom-
mend, "Logistic support capacity should be strengthened in coun-
tries considering IRS for early response or prevention(10)."

But, despite these positive statements, the AMR 2003 report only
actually mentions IRS five times in the entire 112 page document
and then only in passing. Despite mentioning the need to support
IRS programmes, the report does not discuss how and when logis-
tical support will be provided to IRS programmes nor who will
provide it. The report claims to have used the best information
available to the WHO and UNICEF and also draws from sample sur-
veys and routine reports. Yet there is no meaningful discussion
of IRS and no reporting of some of the highly successful IRS
programmes in southern Africa. As mentioned above, IRS remains
the primary method of malaria control for South Africa, Swazi-
land, Mozambique, Namibia, and Zimbabwe and is increasing in use
in Zambia. According to Southern Africa Malaria Control (SAMC),
IRS programmes that use DDT protect 15 million people in Africa.

Neglecting to mention IRS' important contributions to malaria
control is a serious flaw of the report. This failure is either
an oversight, despite the claim that the report uses the best
available information, or a deliberate attempt by the WHO to un-
dermine the efforts of those countries that currently base ma-
laria control on IRS and would consider expanding their IRS pro-
grammes. Either way, the scientific community wishes a clear ex-
planation for this significant shortcoming.

The WHO is well aware of the important role that IRS and insec-
ticides such as DDT play in malaria control. In February 2000,
African delegates to the Regional Consultation to Prepare Afri-
can Countries Towards Reduction of Reliance on DDT for Malaria
Control in Harare, Zimbabwe(11), made a number of clear and un-
ambiguous recommendations to the WHO. The delegates recommended
* WHO should advocate and highlight, at any relevant and appro-
priate forum, the deep concerns of the participating member
states on the possible economic and health implications of any
restriction made on DDT use for malaria control.
* WHO, in collaboration with partners, should ensure that the
necessary technical and financial support is available to member
states for implementation of integrated, evidence based and cost
effective vector control programs to ensure sustainable reduc-
tion of malaria burden.
* WHO should commission a consolidated review of potential eco-
nomic, environmental and health consequences for African coun-
tries of replacing DDT with alternative insecticides for vector

In March 2000, the then project manager of RBM, David Nabarro
supported this stance, saying, "A premature shift to less effec-
tive or more costly alternatives to DDT is likely to be unsus-
tainable. Countries need time and resources to evaluate and se-
lect alternatives that are locally appropriate and sustainable.
In the meantime they need the reassurance that DDT can be used,
if needed, to protect human lives. This is simply good planning,
and good planning needs time and cash." Nabarro went on to say
that finding alternatives to DDT would require "significant new
investment by the global community in research and capacity
building(12)." In November 2000 an official WHO press release
stated, "For many malaria-affected communities, responsible DDT
use is a vital strategy for preventing malaria transmission and
controlling epidemics(13)."

Despite these statements, WHO has failed to give practical as-
sistance in supporting those countries that are using DDT re-
sponsibly in malaria control and in finding new insecticides for
IRS. Far from devoting cash and time to research and capacity
building, the WHO, along with its sister organisation, the UN
Environment Programme (UNEP), has continued to push an agenda of
reduced IRS and reduced DDT spraying in Africa. The WHO's Com-
posite Workplan to Roll Back Malaria from 2000 - 2001 includes
plans to devote US$ 105 000 to technical support and training in
vector control and US$ 577 000 to investigate alternative pesti-
cides and application methodologies(14). Although IRS programmes
could conceivably use some of these investigations, the majority
of vector control disease prevention focuses on ITNs and other
non-IRS vector control. Under the heading of Disease Prevention,
the WHO devotes US$ 1 103 000 to ITN, insecticide treated mate-
rials (ITMs) and biological control research and policy forma-
tion(15). In addition, the same planning document includes the
planned expenditure of US$ 1 500 000 on "Support for policy dia-
logue and action plan development to reduce reliance on DDT
within efforts to RBM(16)." In all we estimate that this WHO
document allocates US$2.5million to vector control efforts that
focus on ITNs, ITMs and biological control and reducing DDT use,
while devoting only approximately half of that amount to pro-
jects that IRS programmes could use(17).

Finding new and effective insecticides for IRS programmes is es-
sential. WHO's anti-IRS and anti-DDT political positions hamper
malaria control efforts and ultimately cost lives. Clearly, the
WHO failed to act upon the recommendation of the African dele-
gates to the February 2000 meeting in Harare. The WHO has main-
tained its anti-DDT and anti-IRS stance, as further evidenced by
the recent Africa Malaria Report. Furthermore it appears that
the WHO has failed to create the necessary public private part-
nerships(18) to create new much needed insecticides for IRS and
has not adequately researched the health and economic implica-
tions of forcing African countries away from IRS and towards its
chosen method of vector control, ITNs.

The policy stance against IRS contrasts not only with the ma-
laria control policies and activities of most southern African
nations, but also with the clearly stated wishes of African
leaders. In April 2003, the South African Minister of Health was
widely quoted in her defence of the use of DDT and the South Af-
rican IRS programme and urged other African countries to not
only use, but also expand the use of DDT. The Ugandan Minister
of Health recently made similar calls, and in Nigeria, Kenya and
Tanzania, researchers and politicians have made impassioned
pleas for the return of DDT based IRS programmes.

Well-managed IRS programmes are essential if malarial countries
are to introduce new drug therapies. In the face of growing drug
resistance in most malarial areas, the need to introduce new and
effective drug therapies is paramount. The most effective thera-
pies available at the moment, artemesinin-based combination
therapies, are significantly more expensive than the alterna-
tives of suphadoxine-pyramethamine and chloroquine. If countries
need to introduce these more expensive and more effective reme-
dies, they need to lower the malaria caseload so that they have
fewer patients to treat. Evidence from many different countries
has shown that IRS is crucial in rapidly and dramatically lower-
ing that case load. Therefore, any attempts to introduce new
drug therapies without comprehensive IRS programmes are likely
to end in failure.

Finally, in support of our concerns, we draw attention to a re-
cent World Bank study that evaluates different malaria control
methods in the Solomon Islands. It concluded that while indoor
residual spraying with DDT and bednet use have their places,
bednets alone could not replace DDT use without an increase in
the number of malaria cases(19).

Conclusions and recommendations

We support the use of IRS as an important tool in the fight
against malaria. We do not reject the other methods of control,
such as ITNs that are championed by the WHO and biological con-
trols, however we firmly believe that these methods and IRS are
not mutually exclusive. Furthermore by undermining IRS efforts,
the WHO is greatly harming malaria control programmes.

* We call on RBM to begin to support IRS programmes where in-
country malaria control programmes see a need for them. This
support requires the WHO to engage with IRS experts from around
the globe to provide the necessary logistical and scientific
support to those countries. In addition, the WHO should advise
and encourage donors agencies, such as USAID, DFID and UN agen-
cies such as UNICEF to fund IRS programmes and to provide the
logistical support to run these programmes effectively.
* We call on the WHO to create a public private partnership that
aims to develop new and alternative insecticides for IRS pro-
grammes. We further call on the WHO to immediately withdraw its
support of the campaigns designed to force malarial countries
away from IRS and away from use of DDT in particular; campaigns
that we feel greatly undermine malaria control.


1. Roberts DR, Alecrim WD, Hsheih P, Grieco JP, Bangs M, Andre
RG, and Chareonviriyaphap T. 2000. A probability model of vector
behavior: Effects of DDT repellency, irritancy, and toxicity in
malaria control. J Vector Ecol 25(1):48-61.

2. Kennedy JS. 1947. The excitant and repellent effects on mos-
quitoes of sub-lethal contacts with DDT. Bulletin of Entomologi-
cal Research 37:593-607.

3. Grieco JP, Achee NL, Andre RG, Roberts DR. 2000. A comparison
study of house entering and exiting behavior of Anopheles vesti-
tipennis (Diptera: Culicidae) using experimental huts sprayed
with DDT or deltamethrin in the southern district of Toledo, Be-
lize, C.A. Journal of Vector Ecology 25:62-73.
4. Roberts DR, Hshieh PB. 2003. What is the role of insecticide
resistance in the re-emergence of major arthropod-borne dis-
eases? In: Institute of Medicine report "The resistance phenome-
non in microbes and infectious disease vectors: Implications for
human health and strategies for containment. The National Acad-
emies Press, Washington, D.C.:94-106.

^1 For example, India managed to bring the number of malaria
cases down from an estimated 75 million per annum in 1951 to
just 50 000 in 1961. Sri Lanka had even more spectacular suc-
cess, reducing its malaria cases from around 3 million per annum
shortly after World War II to just 29 cases in 1964. Harrison G.
Mosquitoes, Malaria and Man: A History of the Hostilities since
1880, London: John Murray (1978).

^2 See Sharp B and le Sueur D, "Malaria in South Africa - the
past, the present and selected implications for the future,"
South African Medical Journal, Vol. 86. No. 1 January 1996, pp
83 - 89 for more details on malaria control in South Africa.
Also Harrison G (1978) p 210 and South African Department of
Health "Overview of Malaria Control in South Africa" South Afri-
can Department of Health (1997) Pretoria

^3 WHO Roll Back Malaria - a Global Partnership
http://www/ accessed
26 September 2003

^4 Kunene, S, Personal communication 24 July 2003

^5 Sharp S, Personal communication, 18 August 2003

^6 Sharp, B et al Malaria control by residual insecticide spray-
ing in Chingola and Chililabombwe, Copperbelt Province, Zambia
Trop Med Intern Health 2002:7(9): 72-6

^7 It is notable that the Africa Malaria Report 2003 cites the
Sharp et al. (2002) paper on malaria control on the Zambian Cop-
perbelt to highlight the consequences of the historical break-
down of malaria control on the Zambian Copperbelt, but not to
highlight the primary focus of the paper, the successful IRS

^8 OAU The Abuja Declaration on Roll Back Malaria in Africa
Point 3 25 April 2003, Abuja, Nigeria

^9 WHO Africa Malaria Report 2003, p 12

^10 ibid. p. 51-2

^11 WHO Delegates Report of the Regional Consultation to Prepare
African Countries Towards Reduction of Reliance on DDT for Ma-
laria Control. Harare, Zimbabwe, 8 - 10 February.

^12 WHO Press Release WHO/15 "Time Limited Exemptions and Finan-
cial Support are Critical to Sustainable Reductions in the Use
of DDT." 17 March 2000

^13 WHO Note for the Press No 15. DDT Use in Malaria Prevention
and Control 28 November 2000. Geneva. Accessed 29 Septem-
ber 2003

^14 WHO Composite Workplan to Roll Back Malaria 2000 - 2001 WHO,
Geneva, December 1999, items 3.1.20 and 3.1.21.

^15 Ibid, item 3.1.19 Standards for mosquito netting and insec-
ticides and test procedures for bioassay of residual insecti-
cides on netting (US$ 150 000); 3.1.24 Guidelines for the use of
insecticide treated materials in malaria vector control (US$ 300
000); 3.1.25 Technical guidelines and guidance for programme im-
plementation of insecticide treated netting materials (US$ 200
000); 3.1.26 Guidelines and training materials on use of insec-
ticide treated nets (AFRO) (US$ 10 000); 3.1.27 Country strate-
gies of introduction of ITMs at district level (US$ 323 000);
3.1.28 Guidelines on biological control, including larvivorous
fish (US$ 30 000).

^16 Ibid. item 5.4.5

^17 Given the anti-IRS stance within the WHO, it is unlikely
that any significant portion of this research will be devoted to
developing new insecticides for IRS or towards improving IRS

^18 Note that the WHO has shown that when motivated, it can be
instrumental in forming public private partnerships, as it has
done with the Medicines for Malaria Venture (MMV) , a highly
promising partnership to produce new anti-malarial drugs.

^19 Bernard Bakote'e, et al. "Impregnated Nets Cannot Fully Sub-
stitute for DDT: The Field Effectiveness of Alternative Methods
of Malaria Prevention in Solomon Islands, 1993-99" Washington
DC: World Bank (2003). "A recent review comparing worldwide tri-
als of impregnated bednets and house spraying for malaria con-
trol suggested that pyrethroid treated nets were as effective as
house spraying with DDT, malathion, or a pyrethroid. However,
recent insecticide treated net trials appeared to be less effec-
tive than spraying programs conducted in the same areas over 30
years ago with non-pyrethroid insecticides including DDT,
malathion, and dieldrin. The evidence from the current study and
all other previous studies in Melanesia suggest that impregnated
bednets cannot easily replace DDT spraying without substantial
increases in malaria incidence."

Hamisi Masanja Malebo
Research Scientist (Medicinal & Bio-Organic Chemistry)
National Institute for Medical Research (NIMR)
P.O. Box 9653, Dar es Salaam, Tanzania
Mobile: +255-744-383-143
Fax: +255-22-2121-360/380 

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