Guidelines for Laboratory and Field Testing of Long-Lasting Insecticidal Mosquito Nets

The purpose of this document is to provide specific and standardized procedures and guidelines for testing long-lasting insecticidal mosquito nets (LNs) for personal protection and malaria control. It is intended to harmonize the testing procedures carried out to generate data for registration and labelling of such products by national authorities.

An LN is a factory-treated mosquito net expected to retain its biological activity for a minimum number of standard World Health Organization (WHO) washes and a minimum period of time under field conditions. Currently, an LN would be expected to retain biological activity for at least 20 standard WHO washes under laboratory conditions and 3 years of recommended use under field conditions, as defined in these guidelines. The guidelines do not include the testing/evaluation of products for long-lasting postfactory treatment of mosquito nets, which will be subject to separate WHO guidelines, or of the LNs that may use insecticides not currently recommended by WHO for such application. Rather, they reflect the current state of knowledge on LN technology and will be subject to revision as more information becomes available.

The guidelines were reviewed and recommended by the WHO Pesticide Evaluation Scheme (WHOPES) Informal Consultation on the development of guidelines for testing/evaluation of long-lasting insecticidal mosquito nets, held at WHO headquarters in Geneva, Switzerland, on 4–7 April 2005.

The document includes laboratory, small- and large-scale field studies to determine the efficacy and operational acceptability of an LN, as summarized below. Although some observations on the safety of such nets will be carried out in the field, a preliminary safety assessment has to be undertaken, following the generic risk assessment model developed by WHO for this purpose, before any field study can be done. In addition, the physical properties of the fabric and factors relating to its structural integrity should conform to WHO specifications for netting materials.