Table 1 Comparison of advantages and drawbacks of both WHO and CDC methods

Advantages

WHO

-WHO papers are always ordered in the impregnated form

-Knock down (Kd) or dead mosquitoes recording in WHO tubes is easy

-insecticide diagnostic doses recommended by WHO for susceptibility tests are standard

-WHO assay requires the purchase of all components (WHO kit) from a centralized source and that allows easy comparison of results from one year to another and from one

study site to another

CDC

-CDC bioassay uses less mosquitoes than WHO bioassay

-CDC bottles bioassay does not need mosquitoes transferred from one bottle to another

-CDC bioassay allows detection of simple or multiple resistance mechanisms in insecticide resistant mosquitoes

-bottle assay is simple and rapid

-some of the components of bottle assay (CDC kit) are more readily and cheaply available

-any concentration of any insecticide (pure or formulated) may be evaluated with bottle assays

-bottle bioassay can also measure the efficacy of an insecticide formulation

Drawbacks

WHO

-mosquitoes transferred from one tube to another need care during WHO cylinder tube test

-WHO bioassay requires 24 hours mortality recording after putting mosquitoes in stable conditions of temperature and humidity

-no provision is made in WHO kit for using synergist in detection of metabolic resistance mechanisms

-increasing the cost of WHO kit and logical complexity of the assay

CDC

-CDC bottles need to be coated with insecticide by oneself before each bioassay

-shelf-life and re-use of pre-prepared bottles are still not well documented or studied in laboratory conditions

-mortality recording in Wheaton bottles necessitates care and is not easy