Mefloquine chemoprophylaxis in Chinese railway workers on contract in Nigeria

BACKGROUND: Nonimmune Chinese nationals on a 2-year railway contract job were commenced on mefloquine (MQ) chemoprophylaxis 20 weeks after arrival in Nigeria. The objective of the study was to determine the usefulness of mefloquine (MQ) (despite the delay in starting) and its tolerability in this group. METHODS: Ninety-one workers (89 males, 2 females) were commenced on weekly MQ 250 mg doses for 17 weeks. Most of the subjects were followed up to 16 weeks after cessation of chemoprophylaxis. The morbidity pattern before, during, and after cessation of chemoprophylaxis was compared. RESULTS: Of the 91 workers included in the study, 89 were evaluable. Three (3.37%) of these developed clinical illness during the 17-week period of chemoprophylaxis. This protection was highly significant when compared to 23 of 91 people (25.27%) who developed clinical illness before chemoprophylaxis was commenced (RR 0.13, 95% CI 0.04-0.43, p <.001). The risk of developing acute malaria increased more than three times, among 84 members of the group who were followed up to 16 weeks after MQ was discontinued (RR 3.18, 95% CI 0.89-11.34). Two subjects withdrew after the second dose due to adverse reactions, however the remaining 89 subjects tolerated the drug for the 16-week period. CONCLUSIONS: Mefloquine significantly reduced malaria morbidity in the study group. Pretravel counseling and advice is important in preventing unnecessary deaths and morbidity in nonimmune travelers to malarious areas.