In Western Europe, malaria is not a prevalent health issue due to high-quality sanitation systems and effective public health measures. However, if we consider the options provided, the treatment for malaria typically involves the use of medicines. Mosquito nets and sprays are preventive measures rather than treatments.
Thus, the correct answer to the question of how people in Western Europe treat malaria in the following ways except would likely be:
Mosquito nets.
They are not directly used for treatment of malaria, but for prevention.