The distribution of mosquito nets or bednets impregnated with insecticides such as permethrin or deltamethrin has been shown to be an extremely effective method of malaria prevention. According to a 2015 "Nature" study, mosquito nets averted 68% of an estimated 663 million averted cases of malaria infection since 2000. It is also one of the most cost-effective methods of prevention. These nets can often be obtained for around $2.50–$3.50 (2–3 euros) from the United Nations, the World Health Organization (WHO), and others. ITNs have been shown to be the most cost-effective prevention method against malaria and are part of WHO's Millennium Development Goals (MDGs). Generally LLINs are purchased by donor groups and delivered through in-country distribution networks.