Don’t Let the Bugs Bite

According to the World Health Organisation impregnated bed nets have helped to substantially reduce the number of children infected and killed by malaria in recent years.


At first it feels like a regular dose of influenza, with a headache and painful joints, and sometimes with nausea as well. In the severe form of malaria the patient goes on to experience bursts of fever with convulsions and loss of consciousness.

This form can result in organ failure, leading to death. Malaria is one of the most common infectious diseases in the world. Most often its victims are children, because children’s immune systems are not fully developed. Bayer manager Nadim Mohr has been traveling in Africa and India for months, supporting the quest to control malaria. Mohr, who is 37, has the task of presenting the LifeNet mosquito net to government authorities and organizations as a new milestone in malaria prevention.


million people died of malaria in 2010.

The LifeNet combats the anopheles mosquito, the vector that transmits the disease. The insect only needs to come into contact with the net for a few seconds. During this brief time it absorbs deltamethrin, an insecticide supplied by Bayer and a particularly effective member of a class of active substances known as pyrethroids.

The World Health Organisation (WHO) states that impregnated bed nets have helped to substantially reduce the number of children infected and killed by malaria in recent years. The problem is that the active ingredient on the surface of the fibers in conventional mosquito nets is depleted every time the net is washed. After 20 washes most of these nets stop being effective.

How does LifeNet work?

The advantage of the LifeNet is that it can be washed more often without losing its effect. Deltamethrin is released from the net fibers over a longer period. As a result, the LifeNet exceeds the requirements of the World Health Organisation’s Pesticide Evaluation Scheme (WHOPES) by 50 percent. Another advantage is its user-friendliness. The material is constructed from polymer fibers, making it both extremely tear-resistant and soft to the touch.

These features led the World Health Organisation to recommend the LifeNet in the fight against malaria. The recommendation was preceded by comprehensive field trials in villages in Tanzania, Benin and India which were known to be infested by strains of mosquitoes susceptible or resistant to pyrethroids. Now Nadim Mohr’s job is to spread the word about mosquito nets. He and three other Bayer experts showcase the LifeNet in 44 countries. “It’s an enormous task,” he says. “But it’s one that really is worthwhile.”

Distribution of the nets

He is particularly pleased that “the expectations of the people we talk to are understandably high.” No matter whether he’s visiting health managers in government offices or representatives of non-governmental organizations like the WHO or the Global Fund to Fight Aids, Tuberculosis and Malaria – they all expect great things of the new net now that it has reached the market. “And they all want to know whether it is as good as the reputation that precedes it.”

3.3 billion

people live in high-risk regions.

Nadim Mohr, at any rate, is convinced that the LifeNet will make a substantial contribution to lowering the number of people infected with malaria. American scientists put the number of deaths due to malaria in 2010 at 1.2 million – that’s twice the previous official estimates. Nine out of ten malaria-related deaths happen in Africa, and most of them are children under the age of five. “This figure alone shows how important our work is,” he says.

A child dies every 30 seconds

A doctor at Panzi Hospital in Bukavu looks after a child infected with malaria. Bukavu is situated on the southwestern shore of Lake Kivu in the Democratic Republic of the Congo, Africa. Conditions around bodies of water like this create ideal breeding grounds for anopheles mosquitoes.

A child dies every 30 seconds

Malaria poses an acute threat to half the world’s population. The disease is endemic in more than 100 countries.

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And around 3.3 billion people live in high-risk regions, places where the 50 species of anopheles mosquito capable of transmitting malaria are prevalent. These species are the only ones among the 2,500 or so species of biting mosquitoes that are capable of ingesting the plasmodia which cause the disease and thus of transmitting malaria.

The countries worst affected by malaria lie south of the Sahara desert. This is where most of the infections and deaths are reported. In its 2011 World Malaria Report, the WHO estimates that there were 216 million cases of malaria in 2010, 81 percent of them in Africa. A child dies of this disease every 30 seconds in Africa.

But countries in Asia, Latin America, the Middle East and parts of Europe also experience outbreaks of malaria. Pregnant women, people infected with HIV and children under five living in high-risk areas are particularly likely to contract malaria which takes a severe course.

Experts fear that the tropical disease could spread even further afield in the coming years as a result of climate change. If average temperatures rise by one or two degrees Celsius, this will expand the area into which mosquitoes can carry the disease.

Fine fibers with a huge impact

They are sometimes as rough as cleaning cloths, so people use them as carrier bags or soccer nets rather than for protection. Conventional mosquito nets often provide too little protection against malaria. They are made of fabric based on polyethylene or polyester and don’t last longer than 20 washes. After this time their quality is too poor to provide the necessary protection.

Bayer responded to this situation by developing a mosquito net which combines long-lasting protection with user-friendliness. It was a two-part task: firstly to make the net last longer, and secondly to give it a pleasant feel.

Dr. Sebastian Horstmann

Dr. Sebastian Horstmann, a researcher at Bayer, studies malaria mosquitoes after they have been treated with an active substance. He can tell from their movements how the substance is affecting them.

Shivering is a warning sign

Malaria becomes evident about 10 to 15 days after the patient has been infected. The initial symptoms are generally fever, headaches, chills and vomiting.

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If these symptoms develop during or shortly after a trip to the tropics, doctors know where to start looking. Until proven otherwise, any feverish response during or shortly after a trip to tropical climes is treated as malaria.

The most reliable way to diagnose the disease is by testing the patient’s blood. A drop of blood is dried, stained, and examined under a microscope. A blood smear is tested every six hours over the course of a day. If the patient is infected with malaria, plasmodia can be seen in the red blood cells. Nowadays rapid tests are also available which demonstrate the presence of the pathogen on the basis of its molecular biology. Malaria can be treated with a number of medicines, but the main thing is to start treating it immediately. It can otherwise take a severe course, possibly leading to a fatal outcome. Ideally, the patient should start taking medication within 24 hours of the first symptoms occurring.

The development of the LifeNet kicked off at the first global malaria forum in 2007. At the same time, the Bill & Melinda Gates Foundation called on “the international donor community and industry” to substantially improve the quality of mosquito nets. This appeal was reiterated at the second forum in 2011, particularly since funding for the control of the feared tropical disease was on the decline. In their search for a suitable fiber material, the researchers at Bayer turned their attention to polypropylene, a plastic that is widely used to produce dashboards, seats for children and yogurt pots. And carpet fibers.

People living in regions where malaria is endemic can use our long-acting mosquito nets to protect themselves effectively against biting mosquitoes.

Thick fibers. “They were no use for weaving fine mosquito nets,” recalls Dr. Maren Heinemann from Bayer Technology Services. She and her colleague Dr. Jens Hepperle developed an innovative manufacturing process – and together they discovered a completely new way of incorporating the active substance into the fibers. “Highly concentrated deltamethrin is kneaded into the molten polypropylene until the active substance is completely and homogeneously blended with the plastic,” Hepperle explains.

Even if the deltamethrin on the surface of the fibers is washed off, the net still remains effective for a long time. The even distribution of the insecticide in the polypropylene fibers means that there is a reservoir of the substance inside the fiber material which gradually migrates to the surface.

This is what makes the LifeNet unique. Project manager Dr. Rainer Sonneck comments, “Our net can still be completely effective even after 35 washes, and it is also extremely tough, resistant to tearing and user-friendly as well.” Bayer’s product therefore complies with the requirements of the Gates Foundation and sets new standards in the fight to control malaria.