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20th April 2016, Obertshausen

Karl Mayer's warp-knitted mosquito nets offer protection against Zika virus

In response to the recent outbreak of the Zika virus, spread by the yellow-fever and tiger mosquitoes, and the existing problem of malaria, the World Health Organization (WHO) has recommended that all the public health authorities worldwide use insect-proof nets having long-lasting insecticidal effects (LLINs).

Karl Mayer, the leading warp knitting machinery manufacturer, offers its two-bar tricot machines, such as the TM 2 and HKS 2-M, that can be used to efficiently produce the warp-knitted mosquito nets using the fine-meshed textiles.

High-precision production

Warp-knitted mosquito nets are mainly produced on two-bar tricot machines, such as the TM 2 and HKS 2-M. According to Karl Mayer, its machines are designed to offer the best in terms of quality and productivity. The machines operate in gauges E 28 or E 32 when working polyester filament yarns. If polyethylene (HDPE) monofilament yarns are used, they are worked usually in gauge E 14, but slight variations above or below this are also feasible.

Warp knitting elements of the TM 2. © Karl Mayer

The two types of yarns have different constructions and properties and also differ as to how they are used in conjunction with the insecticide. Whilst the warp-knitted polyester textile is impregnated with the chemical at the finishing stage, the agent is already present in the HDPE at the granulate stage.

Despite their high operating speeds, Karl Mayer’s tricot machines are also said to offer maximum precision, which allows them to meet stringent requirements in terms of dimensional stability and uniformity of the mesh openings, tear resistance and weight per unit area. In addition to tricot machines, raschel machines having three guide bars can also be used to produce certain products.

Mechanical and chemical protection

The nets must have a specific construction to provide safe and reliable protection against mosquito bites. The required textile parameters include a defined number of mesh holes and this should be 156 holes/inch2 or 25 holes/cm2 when using polyester (PES) filament yarns.

Modern mosquito nets meet this requirement by having stitch densities of 8 to 10 holes/cm when using polyester multifilament yarns, depending on the construction. The textile nets must also have a specific strength, so that the mosquitoes cannot make holes in them.

Construction of a warp-knitted mosquito net. © Karl Mayer

In addition to the mechanical protection provided by the textile construction, mosquito nets also provide chemical protection by treating them with a contact insecticide. The most frequently used pyrethroids are applied to the nets by a standard impregnation process or by long lasting impregnation (LLI). Products that have been treated by the standard impregnation process lose their effectiveness after six months and after every wash, and the insecticide has to be re-applied regularly. LLI mosquito nets, on the other hand, can be used for more than three years and washed up to twenty times.

Zika virus

The consequences of the Zika virus infection, suspected of causing microcephaly, a developmental disorder that affects unborn babies, are miscarriages and babies born with small heads, who are likely to be severely mentally handicapped. According to the WHO, 33 countries had already been affected by the spread of this dangerous virus by February of this year, with Brazil and Colombia being the worst affected countries.

The transfer of malaria pathogens is also just as dangerous to humans. A child dies every 30 seconds from the tropical disease known as swamp fever or malaria. But malaria is also responsible for a high number of deaths among adults. This disease is prevalent in 106 countries globally and is a threat to more than half of the world’s population.


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