Department of Infectious Diseases, Public Health Service (GGD) of Amsterdam, Nieuwe Achtergracht 100, PO Box 2200, 1000 CE, Amsterdam, the Netherlands; National Coordination Centre for Travellers' Health Advice (LCR), Nieuwe Achtergracht 100, PO Box 1008, 1000 BA, Amsterdam, the Netherlands; Center of Tropical Medicine and Travel Medicine, Department of Infectious Diseases, Amsterdam University Medical Centers, Location AMC, Amsterdam Infection & Immunity, Amsterdam Public Health, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, the Netherlands.
Department of Infectious Diseases, Public Health Service (GGD) of Amsterdam, Nieuwe Achtergracht 100, PO Box 2200, 1000 CE, Amsterdam, the Netherlands.
Travel Med Infect Dis. 2022 Sep-Oct;49:102406. doi: 10.1016/j.tmaid.2022.102406. Epub 2022 Aug 4.
Chemoprophylaxis and anti-mosquito measures are key to preventing malaria in travelers. Long-term travelers are at higher risk than short-term travelers, but their adherence to preventive measures is lower. Our aim was to determine malaria exposure risks and predictors for adherence to malaria-preventive measures in long-term travelers.
Long-term travelers (>12 weeks) completed a weekly questionnaire about preventive measures, symptoms, and malaria treatment abroad. Blood samples were tested for seroconversion to Plasmodium falciparum anti-circumsporozoite (PfCSP) antibody. Adherence to preventive measures was defined as number of weeks of their usage divided by number of weeks in malaria-endemic areas.
Of 561 travelers, the median travel time was 20 weeks (IQR 16-25). Eighteen were treated for malaria, all in sub-Saharan Africa. Sixteen PfCSP seroconversions were found, of whom only 3 had traveled to high-endemic areas. Of the 18 travelers treated for malaria, only one seroconverted. No associations were found between covariates and seroconversion. Neither treatment abroad nor seroconversion were reliable predictors for exposure. 'Full adherence' to chemoprophylaxis was reported by 52% (218/417) and was associated with travel to Africa, use of mefloquine, lack of prior travel history, shorter duration of travel, and use of DEET.
The risk of malaria in this long-term travelers cohort was low. Our data confirm that anti-PfCSP seroconversion is not a reliable method to retrospectively identify incident infection, or probably exposure. Prevention efforts should focus on more experienced travellers and longer travel duration, for whom mefloquine should be considered as the first-choice chemoprophylaxis.
化学预防和防蚊措施是旅行者预防疟疾的关键。长期旅行者比短期旅行者面临更高的风险，但他们对预防措施的依从性较低。我们的目的是确定长期旅行者中疟疾暴露风险和预防措施依从性的预测因素。
长期旅行者（>12 周）每周填写一份关于预防措施、症状和国外疟疾治疗的问卷。采集血样检测对恶性疟原虫环子孢子蛋白（PfCSP）抗体的血清转化。预防措施的依从性定义为使用预防措施的周数除以疟疾流行地区的周数。
561 名旅行者中，中位旅行时间为 20 周（IQR 16-25）。18 人因疟疾在国外接受治疗，均在撒哈拉以南非洲。发现 16 例 PfCSP 血清转化，其中仅 3 例曾前往高流行地区。在因疟疾接受治疗的 18 名旅行者中，仅有 1 人血清转化。协变量与血清转化之间未发现相关性。在国外治疗或血清转化均不是暴露的可靠预测因素。417 名接受化学预防的旅行者中，有 52%（218/417）报告“完全依从”，与前往非洲、使用甲氟喹、无既往旅行史、旅行时间较短以及使用 DEET 有关。
本长期旅行者队列中疟疾的风险较低。我们的数据证实，抗 PfCSP 血清转化不能可靠地用于回顾性识别感染事件或可能的暴露。预防措施应侧重于经验更丰富的旅行者和更长的旅行时间，对于这些旅行者，应考虑使用甲氟喹作为首选化学预防药物。
