Malaria prevention strategies and recommendations, from chemoprophylaxis to stand-by emergency treatment: a 10-year prospective study in a Swiss Travel Clinic

Adherence to antimalarial chemoprophylaxis among Israeli travelers visiting malaria-endemic areas

BACKGROUND

Travelers are recommended to take antimalarial chemoprophylaxis (AMC) when traveling to endemic areas.

METHODS

This prospective comparative cohort study included 400 Israeli travelers to malaria-endemic areas, recruited in pre-travel clinics. They were contacted within one month following their return and asked about their actual adherence and the reasons for non-adherence.

RESULTS

Of 400 travelers with a mean age of 24.6 [SD = 4] years, 201 (50.2%) were men and 328 (82%) were singles. The majority (N = 185, 46.3%) traveled with friends, and the most common travel destination was southeast Asia (N = 267, 66.8%). Most travelers (N = 340, 85%) did not adhere to the AMC. In the multivariate analysis, non-adherence was found to be significantly associated with traveling solo or with friends, traveling to southeast Asia and longer travel duration. The most common reason for non-adherence among travelers was the perception that the risk of contracting malaria is low (N = 251, 73.8%).

CONCLUSION

In this study, 85% of the Israeli travelers did not adhere to the AMC, especially those traveling solo or with friends, visiting southeast Asia and for a long period. Counselors at the pre-travel clinics should stress the importance of AMC in highly endemic countries and consider alternative treatment strategies, especially in low risk areas or long duration travel, such as short-term schedule or reserve AMC for field trips.

Malaria standby emergency treatment (SBET) for travellers visiting malaria endemic areas: a systematic review and meta-analysis

BACKGROUND

Malaria prevention methods for travellers to low or moderate malaria risk areas vary and remain controversial. Standby emergency treatment (SBET) for malaria is one possible strategy increasingly recommended since 1988 with little evidence on its effectiveness or how it is truly being used.

METHODS

A systematic review and meta-analysis were performed based on a structured search in Embase, Medline, PubMed, Cochrane and Web of Science on 7 September 2018. The primary outcome was the overall prevalence of SBET use in travellers, and secondary outcomes were the proportion carrying SBET, the response to fever [use of SBET, health facility attendance and use of malaria rapid diagnostic test (mRDT)], adverse events to SBET and the proportion using SBET incorrectly (incorrect dosage/duration). The pooled SBET use prevalence was analysed using a random effects model. A descriptive summary was done to present secondary outcomes. The study protocol was registered with PROSPERO CRD42018103703.

RESULTS

A total of 11 studies were eligible for inclusion among the 1027 titles identified by our search. The studies included 7/11 prospective cohort studies that recruited pre-travel clinic attendees in Europe and 4/11 cross-sectional studies, of which 3 recruited travellers at airports before their return home from Southeast Asia and Africa and 1 from an employee registry including long-term travellers. The overall pooled prevalence of SBET use among the 26 403 travellers was 2.5% (95% confidence interval, 1.1-4.3%; range, 0.4-10.8%). There was significant variation in the proportion of travellers carrying SBET medication (40-100%), the proportion of travellers with appropriate response to fever (23-100%), adverse events (0-33%) and incorrect dosage/duration of SBET (0-100%).

CONCLUSION

Adherence to the proposed recommendations for SBET use, notably the response to fever, was poor. If the use of SBET is to be pursued, modifications to the current SBET strategy should be considered, such as better selection of travellers at higher risk for malaria and the potential addition of mRDTs.

Stand-by emergency treatment (SBET) of malaria in Spanish travellers: a cohort study

Background

Among strategies for malaria prevention, stand-by emergency treatment (SBET) is a possible approach, but scarce evidences exists investigating travellers’ adherence and behaviours toward its use; therefore, the presented study aimed to determine travellers’ compliance toward the SBET when prescribed in travel clinics.

Methods

A prospective cohort study was performed at the Travel Health Clinic of the Hospital Universitari de Bellvitge, Barcelona, Spain, during 2017. The research was planned on survey-based design, using pre- and post-travel questionnaires.

Results

In the study period, of 5436 subjects who attended the HUB Travel Medicine Clinic, 145 travellers to malaria-endemic areas were prescribed SBET, and all patients agreed to participate in the study by completing the pre-travel questionnaire. Approximately half the participants were women (n = 75, 51.7%), and the median age of all travellers was 29 years (range 13–57), mainly travelling to South-East Asia (n = 69, 47.6%), with Indonesia and the Philippines as the most popular destinations. The length of travels had a median duration of 29 days (range 10–213). Of the recruited participants, 98 replied to the online post-travel survey, reaching a response rate of 67.6%. A total of 62.2% of travellers to which SBET was prescribed did not buy and carry drugs while travelling abroad. No participants’ baseline or travel characteristic was shown to be significantly associated (p > 0.05) with this behaviour. Four women (4.1%) experienced fever and self-administered SBET, without seeking medical attention. No malaria cases were observed.

Conclusions

This cohort study addressed travellers’ adherence and behaviour toward SBET, highlighting an incorrect use of the emergency treatment in case of presumptive malaria symptoms. This should be taken into account during pre-travel consultation, since the success of this strategy for malaria prevention depends on travellers’ strong adherence to it.

Tafenoquine for travelers' malaria: evidence, rationale and recommendations

Background

Endemic malaria occurring across much of the globe threatens millions of exposed travelers. While unknown numbers of them suffer acute attacks while traveling, each year thousands return from travel and become stricken in the weeks and months following exposure. This represents perhaps the most serious, prevalent and complex problem faced by providers of travel medicine services. Since before World War II, travel medicine practice has relied on synthetic suppressive blood schizontocidal drugs to prevent malaria during exposure, and has applied primaquine for presumptive anti-relapse therapy (post-travel or post-diagnosis of Plasmodium vivax) since 1952. In 2018, the US Food and Drug Administration approved the uses of a new hepatic schizontocidal and hypnozoitocidal 8-aminoquinoline called tafenoquine for the respective prevention of all malarias and for the treatment of those that relapse (P. vivax and Plasmodium ovale).

Methods

The evidence and rationale for tafenoquine for the prevention and treatment of malaria was gathered by means of a standard search of the medical literature along with the package inserts for the tafenoquine products Arakoda™ and Krintafel™ for the prevention of all malarias and the treatment of relapsing malarias, respectively.

Results

The development of tafenoquine-an endeavor of 40 years-at last brings two powerful advantages to travel medicine practice against the malaria threat: (i) a weekly regimen of causal prophylaxis; and (ii) a single-dose radical cure for patients infected by vivax or ovale malarias.

Conclusions

Although broad clinical experience remains to be gathered, tafenoquine appears to promise more practical and effective prevention and treatment of malaria. Tafenoquine thus applied includes important biological and clinical complexities explained in this review, with particular regard to the problem of hemolytic toxicity in G6PD-deficient patients.