Malaria in pregnant women and infants, and in preschool children where transmission is seasonal. There are a number of medications that can help prevent or interrupt malaria in travelers to places where infection is common. Many of these medications are also used in treatment. In places where "Plasmodium" is resistant to one or more medications, three medications—mefloquine, doxycycline , or the combination of atovaquone/proguanil ("Malarone")—are frequently used for prevention. Doxycycline and the atovaquone/proguanil are better tolerated while mefloquine is taken once a week. Areas of the world with chloroquine sensitive malaria are uncommon. The protective effect does not begin immediately, and
Mefloquine of the users reported severe events requiring medical attention, vs 1.2% in the atovaquone-proguanil arm. The brand name drug, Lariam, is manufactured by the Swiss company Hoffmann–La Roche. In August 2009, Roche stopped marketing Lariam in the United States. In June 2010, the first case report appeared of a progressive multifocal leukoencephalopathy being successfully treated with mefloquine. Mefloquine can also act against the JC virus. Administration of mefloquine seemed to eliminate the virus from the patient's body and prevented further neurological deterioration. WRAIR has published several papers outlining ongoing efforts at that institution to make mefloquine safer by producing a