Subject: Quality criteria for choosing mosquito nets

Author: Africa Malaria Adviser at IFRC

Date: 05-05-04 11:31

Dear Thomas,

Concerning your query on choosing among the mosquito net offers in

your tender there are, besides price, the following other criteria to

be taken into consideration with a ranking:

A Raggedness of the fibre:

1 Polyethylene (5-7 years)

2 Polyester 100 Denier (3-4 years)

3 Cotton 3 years

4 Polyester Denier 75 (1-3 years)

5 Nylon (1 year)

B Longevity of Insecticidal/insect repellent activity:

1 Olyset (Polyethylene) (5 years WHO confirmed)

2 Permanet 2.0 (2-3 years est. not yet WHO confirmed)

3 Pre-impregnated ITN (9 months to max. 1 year)

4 Non impregnated polyester mosquito net (0 months)

When comparing net prices you can calculate the price of one

impregnation at 036 cent/ net for the insecticide kit and 0.50 US$ for

re-impregnation programme cost and multiply that by numbers of years of

ITN use.

5 Impregnated cotton nets have only about half the longevity of

insecticide at the same dose because insecticide gets trapped within

the fibre where it is not bioactive.

C Wash resistance of insecticide

2 Permanet 2.0 (> 20 washes WHO confirmed)

1 Olyset (Polyethylene) (1 week needed to regenerate activity in hot

climes)

3 Pre-impregnated ITN (max. 3 washes)

4 Non impregnated mosquito net (0 months)

You have to calculate price + 036 cent/ net for insecticide kit and

0.50 US$ for re-impregnation programme cost to it to be equal to

pre-impregnate nets

In addition there are other important net qualities that influence

behaviour i.e. usage pattern including the number of persons

protected/net: They include:

1 Size: Often the bigger the better so long as it still fist into the

hut

2 Transparency: often the less transparent the better

3 Colour: Here often dark colours are better because the net looks

clean without washing, some people reject white (Asia) others prefer

white (Togo)

4 "Feel" of the net: here the hierarchy is 1 cotton, 2 polyester 3

polyethylene.

5 Look of the net 1 Polyester, 2 cotton, 3 polyethylene.

Above qualities A-C and size influence price. If the amount of money

is limited it is often better from a public health standpoint to

protect more people with a lesser quality now (and fix this later)

than to protect fewer with top quality.

However each choice must be made given the local circumstances trying

for the best possible fit within limited budget and potential donor

restrictions etc. ITNs are a classical case of "not one size fits

all".

Best wishes,

Stefan