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[afro-nets] Mosquito/Malaria Control (31)

  • From: Tom Oconnell <tsoconnell2@yahoo.com>
  • Date: Fri, 9 Sep 2005 04:10:32 -0700 (PDT)

Mosquito/Malaria Control (31)

Dear All,

Having watched this exchange for some time now, please allow me
to add a few comments.

Dear Bill, your statement is not accurate. Insecticide-Treated
BedNets (ITNs) have at least three important purposes in the
case of the infected person. 1) they protect the person from re-
infection (what you mentioned). 2) they prevent mosquitoes from
biting the infected person and so reduce the chance that the
parasite is passed onto other people. (An extremely important
outcome!) 3) They kill mosquitoes that land on or NEAR the ITN,
preventing other household members from being bitten, i.e. those
near, but not under, nets. Given the small size of most homes, 1
net might have considerable and long-lasting impact.

Field research proves the effectiveness of ITNs, in the above 3
ways, in helping to "breaking the chain of transmission." In
community-wide trials in several African settings, ITNs reduced
all-cause mortality by about 20%! Also, the push is to use long-
lasting ITNs, (LLINs), which last about 3 years. LLINs are more
practical than regular ITNs, which had to be re-treated every 6
months. Research in the field clearly shows ITNs offer important
protection to all community members, even those who do not sleep
under the nets. This is because they both protect from infection
and reduce the spread of infection (as mentioned above). Of
course, they must be coupled with prompt treatment of effective
anti-malarial medications.

Additionally, ITNs are being freely distributed in several major
vaccination campaigns, to help ensure a critical mass (i.e.
enough to be effective) are introduced into communities (e.g. in
Togo, Zambia and Ghana). The International Red Cross/Red Cres-
cent found that in Ghana before distribution of ITNs in a cam-
paign, 20.1% of families had an ITN and 6.0% of children slept
under an ITN. Post-distribution, 80.1% of children slept in a
home with an ITN! The work of the Red Cross on the ground, to
explain to families the importance of bednets and to show how
the use nets effectively, helps build such long-term behavior

Certain types of spraying (e.g. IRS) is often an excellent co-
intervention, BUT only if its use is evidence-based and only if
it is done properly. While the first criteria can be determined
fairly easily, ensuring the second is met is a bigger problem.
For example, EFFECTIVE indoor spraying requires exactly the cor-
rect amount of insecticide applied to the walls and just before
the biting season begins; this rarely happens. Even when I par-
ticipated in careful and extensive training sessions to show
proper application techniques, people get tired, begin to speed
up as a day wears on, forget to recalibrate sprayers, etc.. The
result is too little application of insecticide. Not only will
the protective effect wear off before the end of the biting sea-
son, but low levels of insecticide allow mosquitoes to develop
resistance to insecticides. And all spraying must be reapplied
every few months, compared to LLINs which last up to 3 years.

A second problem of IRS and outdoor spraying (e.g. larvaciding &
aerial spraying) is the difficulty of putting in place the
needed infrastructure to make sure spraying is done correctly
and that sufficient supplies are in place when/where needed. Few
African countries have a strong enough distribution and supply
system to move insecticides around fast enough to guarantee that
sufficient stocks are available when needed. YES, money must be
spent to rapidly build up this capacity. But UNTIL the capacity
is there alternatives must be used now to save lives today. This
is one reason that RBM feels aerial spraying has little practi-
cal application at this time, in Africa, when compared with
other interventions that can reduce death and illness today.

Finally, training costs are ALWAYS greatly underestimated.
Training sprayers is not enough. Success requires strong systems
of supervision, as well as realistic and meaningful compensation
systems so that workers are motivated to spray correctly. Actual
training costs a lot of money and takes a significant period of
time. Short-cuts do not work, and often poorly-trained community
workers are unfairly blamed when effective spraying techniques
are not followed! Aerial spraying requires exact timing and up-
to-date and accurate maps that show mosquito breeding areas.
Such mapping needs to be done, but is not yet available in most
places. The wide-spread use of ITNs can help buy the time to in-
vest in longer-term solutions based on local needs, conditions
and local wishes.

Prevention is only half the battle. To quickly reduce death and
illness, prevention must be combined with equitable, rapid and
universal access to effective treatment. When effective treat-
ment is combined with effective prevention, the chain of infec-
tion is broken. This many-sided approach (multi-method mosquito
control and rapid, effective treatment) is what worked in North
America, not simply widespread spraying.

Best regards,
Tom O'Connell

(Note: While I was privileged to work with the RBM Secretariat
and other RBM partners, I do not now do so. My opinions are
strictly my own and do not represent any other person or group's