Malaria prophylaxis: survey of the response of British travellers to prophylactic advice

A systematic review of factors affecting adherence to malaria chemoprophylaxis amongst travellers from non-endemic countries

Background

The aim of this systematic review was to identify predictors of actual or intended adherence with malaria chemoprophylaxis amongst travellers from non-endemic countries visiting endemic countries.

Methods

A systematic review of the literature was conducted using MEDLINE, Embase, PsycINFO and Global Health databases for studies published up to April 2019. Studies were included if they assessed reasons for adherence among people travelling from a country where malaria was not endemic to a country where it was.

Results

Thirty-two studies were included. Predictors of adherence were categorized as relating to either the nature of the travel or the traveller themselves. The three main predictors associated with nature of travel included: destination (e.g. country visited, urban vs rural areas), length of travel and type of travel (e.g. package vs backpacking holiday). The four main traveller-associated predictors were: age, reason for travel (e.g. business, leisure or visiting friends and relatives), perceived risk of catching malaria and experienced or expected medication effects.

Conclusions

In order to improve adherence, clinicians should focus on travellers who are least likely to exhibit adherent behaviour. This includes travellers visiting destinations known to have lower adherence figures (such as rural areas), backpackers, business travellers, younger travellers and those travelling for longer periods of time. They should also check to ensure travellers’ perceptions of the risks of malaria are realistic. Where appropriate, misperceptions (such as believing that curing malaria is easier than taking prophylaxis or that travellers visiting relatives have some level of innate immunity) should be corrected. All travellers should be informed of the potential side-effects of medication and given guidance on why it is nonetheless beneficial to continue to take prophylaxis. Further research is required to test interventions to improve adherence.

Determinants of Adherence with Malaria Chemoprophylactic Drugs Used in a Traveler's Health Clinic

Background. The WHO recommends mefloquine, atovaquone/proguanil, and doxycycline for malaria chemoprophylaxis. Adherence to a drug is determined by many factors. Objective. To detect the determinants of travelers' adherence to malaria chemoprophylaxis. Methods. A prospective comparative study was conducted from January 2012 to July 2013 that included travelers (928 travelers) to malaria endemic countries who visited the THC. They were classified into 3 groups: the 1st is the mefloquine group (396 travelers), the 2nd is the doxycycline group (370 travelers), and finally those who did not receive any drugs (162 travelers). The participants from the 1st and 2nd groups enrolled in the study. Results. Univariate and multivariate analyses were performed. The predictors for adherence in the mefloquine group were travel to an African destination [OR = 51 (6.8–2385)], higher than a secondary school education [OR = 21 (4.1–144.2)], organized travel [OR = 4 (2.1–6.5)], traveling for leisure [OR = 2.1 (1.1–0.4)], and nationality [OR = 2 (1.11–4.00)]. In the doxycycline group, the predictors included higher than a secondary education [OR = 20.1 (4.5–125.1)], organized travel [OR = 11.4 (5.5–20.9)], travel for leisure [OR = 7 (2.3–22.9)], travel to an African destination [OR = 6.1 (0.41–417)], and nationality [OR = 4.5 (2.3–9.5)]. Conclusion. Adherence with malaria chemoprophylaxis could be affected by many factors such as nationality, education, and organized travel.

Rolling back malaria: how well is Europe doing?

Background. The Roll Back Malaria (RBM) initiative has committed itself to halving the worlds's malaria burden by 2010, having adopted five operationally focused 'critical concepts' to guide this task. The focus of RBM's efforts is in the developing world where external support is often required. Malaria was only recently eradicated from Europe, and the continent remains under continual threat of reintroduction. The extent of this threat is examined, and the European response benchmarked against RBM's critical concepts. Methods. The following sources were searched for references using the phrase "imported malaria": RBM, WHO, European Union including Eurosurveillance, and MedLine websites. Links to related articles were followed. Citations were independently assessed by the authors for relevance and inclusion. Results. Only in application of the critical concept "disease surveillance" does the European response seem adequate. Conclusions. Europe should be making greater efforts and considering additional strategies to combat imported malaria.

Prevention of malaria in long-term travelers

Long-term travellers have a high risk of acquiring malaria, and also of discontinuing malaria prophylaxis. A review by Lin Chen and colleagues addresses the relatively neglected area of malaria prevention in long-term travellers. The essential elements of malaria prevention are discussed: awareness of risk, bite avoidance, chemoprophylaxis, rapid diagnosis, stand-by emergency treatment, and the importance of tailoring recommendations to the individual.

Efficacy of antimalarial chemoprophylaxis among French residents travelling to Africa

Controversy exists about which antimalarial chemoprophylaxis regimen should be used among travellers to Africa: the WHO and other experts recommend the use of mefloquine throughout sub-Saharan Africa, whereas French experts still support the combination of chloroquine and proguanil in most of West Africa (the so-called zone 2 countries). In this case-control study based at a travel clinic, we examined the compliance with antimalarial chemoprophylaxis and its efficacy among travellers to tropical areas. Cases were patients with Plasmodium falciparum malaria (n = 131). Controls were patients who had a negative malaria film (n = 158). Of all controls, only 36 (22.8%) were adequately protected (i.e. compliant with an adapted regimen of chemoprophylaxis). In zone 2 countries, the efficacy of the combined chloroquine and proguanil was 58% (95% CI 22-78%) for all users, but increased to 100% (95% CI 89-100%) for compliant users. In zone 3 countries, the efficacy of mefloquine was 90% (95% CI 51-98%) and 100% (95% CI 58-100%) for all users and compliant users, respectively.

Risk factors for malaria in UK travellers

After observing an apparent increase in severe falciparum malaria among travellers returning from The Gambia to the United Kingdom (UK) in the last quarter of 2000, we conducted a case-control study to investigate risk factors for malaria. The study participants had visited The Gambia between 1 September and 31 December 2000, travelling with the largest UK tour operator serving this destination. The main outcome measures were risk factors associated with malaria. Forty-six cases and 557 controls were studied. Eighty-seven percent of all participants reported antimalarial use (41% chloroquine/proguanil, 31% mefloquine). On univariate analysis the strongest risk factors for disease were: early calendar period of visit, longer duration of stay, non-use of antimalarial prophylaxis, non-use of mefloquine, lack of room air-conditioning, less use of insect repellent, prior visit to another malarial area and accommodation in 'hotel X'. After adjustment in multivariate analysis, use of mefloquine remained strongly protective (odds ratios, OR 0.13 [95% confidence intervals, 95% CI 0.04-0.40]), and the strongest independent risk factors for malaria were early calendar period (OR 5.19 [2.35-11.45] for 1 September to 9 November 2000 versus 10 November to 31 December 2000), prior visit to another malarial area (OR 3.27 [1.41-7.56]), main accommodation in 'hotel X' (OR 3.24 [1.51-6.97]) and duration of stay (OR 2.05 per extra week [1.42-2.95]). Neither any use, nor > 90% adherence to chloroquine/proguanil were protective (adjusted OR for any use 0.57 [0.27-1.21], P = 0.14). We concluded mefloquine use was strongly protective against malaria (87% protective efficacy), whereas chloroquine/proguanil, which is no longer recommended but remains widely used, was less than half as effective (43% protective efficacy). Waning efficacy of chloroquine/proguanil may have contributed to the observed increase in malaria among travellers to The Gambia in 2000. Local factors may also influence the risk of malaria. Malaria could be prevented among travellers to West Africa if current national guidelines on antimalarial prophylaxis were better implemented.

Delayed onset of malaria--implications for chemoprophylaxis in travelers

BACKGROUND

Most antimalarial agents used by travelers act on the parasite's blood stage and therefore do not prevent late-onset illness, particularly that due to species that cause relapsing malaria. We examined the magnitude of this problem among Israeli and American travelers.

METHODS

We examined malaria surveillance data from Israel and the United States to determine the traveler's destination, the infecting species, the type of chemoprophylaxis used, and the incubation period.

RESULTS

In Israel, from 1994 through 1999, there were 300 cases of malaria among returning travelers in which one species of plasmodium could be identified. In 134 of these cases (44.7 percent), the illness developed more than two months after the traveler's return; nearly all of these cases were due to infection with Plasmodium vivax or P. ovale. In 108 of the 134 cases (80.6 percent), the patient had used an antimalarial regimen according to national guidelines. In the United States, from 1992 through 1998, there were 2822 cases of malaria among travelers in which the cause could be evaluated. Late illness developed in 987 (35.0 percent) of these travelers. The infection was due to P. vivax in 811 travelers, P. ovale in 66, P. falciparum in 59, and P. malariae in 51; 614 (62.2 percent) of those with late-onset illness had appropriately taken an effective antimalarial agent.

CONCLUSIONS

In more than one third of malaria-infected travelers, the illness developed more than two months after their return. Most of these late-onset illnesses are not prevented by the commonly used and effective blood schizonticides. Agents that act on the liver phase of malaria parasites are needed for more effective prevention of malaria in travelers.

Referral of travellers from Australia by general practitioners for travel health advice

Background. General practitioners (GPs) may refer travellers to practice staff and to outside agencies to assist in the provision of travel health advice and preventive measures. In Australia, little is known about the referral patterns of travellers for travel health advice by GPs in the Australian context. This study was designed to investigate how frequently GPs' practice staff became involved in providing basic travel health advice and travel vaccination and to identify referral sources and how frequently GPs referred travellers to these sources for travel health advice. Method. In 2000, 433 GPs from western Sydney and Townsville were randomly selected from the register of the Australian Medical Association's Medical Directory of Australia database and sent self-administered questionnaires. Two reminders were sent. Results. Two hundred and thirteen questionnaires (43%) were returned. Approximately two thirds of the sample were male (133/207, 64.3%) and one third female (74/207, 35.7%). The mean age of the GPs was 46.7 (SD+/-12.1) years. About one tenth of GPs reported having a Yellow Fever Licence (11.3%, 23/203). The majority of GPs did not use their practice staff for giving travel health advice (60.7%, 122/201) or giving travel vaccinations (55.7%, 112/201). More than three quarters of GPs would never refer their patients for travel health advice to GPs with a special interest in travel medicine (76.4%, 152/199), specialists (76.8%, 152/198), or other agencies (77.8%, 63/81). Almost half of GPs stated that they would refer to travel clinics at least sometimes (46.6%, 95/204). Conclusions. GPs do sometimes refer travellers to specialised practices for travel health advice, especially to travel clinics, but also to other agencies, possibly for specialised services, such as yellow fever vaccination. Further studies may be needed on capacity of general practice staff to contribute to the travel health consultation and also the reasons and the appropriateness of the referral to outside agencies, where this occurs. Practices may need to consider further training of their auxiliary health staff in travel medicine, so that they can become more involved in the provision of travel health advice and immunization, where possible.

Health problems in a large cohort of Americans traveling to developing countries

BACKGROUND

Millions of Americans visit developing countries each year, however, little is known about their health during travel. This study describes health problems in a large cohort of American travelers during and after their trip.

METHODS

A 2-year survey of 784 travelers (95% follow-up) was conducted for persons traveling for < or = 90 days. At the pretravel visit, travelers were given a postcard to record adverse health events. Following travel, standardized telephone interviews were performed for any positive responses, or if the card was not returned. All travelers were contacted 2 months after return to determine late occurring illness and compliance with antimalarials.

RESULTS

Travelers had a mean age of 44 years, a median duration of 19 days, and visited 123 countries. An illness was reported by 64% (1.6 illnesses per traveler). Ill travelers were more often female, and traveled longer than those who were not ill; depending upon destination, each day of travel increased by 3 to 4% the chance of becoming ill. Diarrhea was most common, occurring in 46%; 34% met a strict definition for traveler's diarrhea. Respiratory illness occurred in 26%, skin disorders in 8%, acute mountain sickness in 6%, motion sickness in 5%, accidents and injuries in 5%, and isolated febrile episodes in 3%. Medical care was sought by 8% of all travelers and 12% of those reporting illness. On return, 26% of travelers were ill, 56% of whom became ill after return. Diarrhea, respiratory illness, skin disorders, and febrile syndromes were most common, and 46% of those who were ill sought medical care. Complete compliance with antimalarials was 80%. Noncompliant individuals usually discontinued medications on return. Side effects were reported by 4% of those taking chloroquine, 11% of those taking chloroquine plus proguanil, and 14% of those taking mefloquine, with half of these neuropsychiatric. The incidence of documented malaria was 3.8 cases per 1,000 travelers.

CONCLUSIONS

Many travelers experience adverse health events during and after travel to the developing world. Attention to the prevention and therapy of traveler's diarrhea, prophylaxis of malaria, management of respiratory illness, personal safety, and access to medical care during travel, and, recognition of clinical syndromes after return, will help to improve the traveler's health.

Use of medical chemoprophylaxis and antimosquito precautions in Danish malaria patients and their traveling companions

BACKGROUND

The number of malaria cases imported to Denmark has been increasing for some years. To analyze the background for this we assessed the use of protective measures in Danish travelers visiting malarious areas.

METHOD

Post-travel questionnaires were given during hospitalization to malaria patients, and sent by mail to their traveling companions.

RESULTS

In total, 142 persons participated. Only 32% of the travelers used chemoprophylaxis correctly, according to Danish recommendations. Twelve percent of the travelers did not use chemoprophylaxis. Average compliance was 52%. Insufficient drug dosage was reported by 13%, and use of nonrecommended drugs by 7% of the travelers. Thirty-seven percent used insufficient antimosquito precautions, a problem which often coincided with irregular use of chemoprophylaxis. Malaria patients, sole travelers, and travelers with other ethnical background than Danish, were subgroups using insufficient malaria prophylaxis more frequently than healthy traveling companions.

CONCLUSION

Insufficient use of the available antimalaria precautions by Danish travelers contributes greatly to maintaining a high incidence of imported malaria. Increased attention from physicians in educating travelers is important for optimizing malaria prophylaxis.

Sources of health advice given to travelers

One of the biggest problems for health professionals and the travel industry has been getting travelers to present for pretravel health advice from a qualified source. Behrens1 stated that one of the most important factors in whether travelers seek health advice at all was the perceived risk and severity of tropical diseases. Travelers may obtain this health advice from the travel industry itself, or from health professionals in travel clinics, hospitals, public health units, general practices or other centers. They may also obtain advice by telephone directly from these areas. It is likely however that travel agents and the travel industry, especially various publications, are an important source of preliminary information on health and safety for travelers.

Knowledge of travel medicine providers: analysis from a continuing education course

BACKGROUND

With millions of international travelers, there has been an increase in the scope and variability of travel medicine providers. A study was conducted to measure the baseline knowledge of providers, determine factors affecting this knowledge, and assess acquisition of knowledge after a continuing education course.

METHODS

A one-day continuing medical education course was held for health care professionals interested in travel medicine. Prior to the course, attendees completed a test determining knowledge in malaria chemoprophylaxis, traveler's diarrhea management, vaccines, jet lag, the returned traveler, and other areas. An identical test was given after completion of the course. Performance on the test was analyzed by profession, area of specialty training, and experience in travel medicine.

RESULTS

Seventy-seven attendees completed the precourse test. Forty-eight percent were physicians and 47% were nurses; 29% specialized in infectious diseases, 22% in occupational medicine and student health, and 18% in family or internal medicine; 60% had >/= 1 year of travel medicine experience while 20% had no experience. The precourse test score for all participants was 62.7% 6 6.5 (sd). Analysis by profession found that physicians scored the highest (71%). Providers with >/= 1 year of travel medicine experience scored higher than those with no experience (67% vs 53%, p <.01). Statistically significant correlations were found between precourse exam results and profession (+.432, p <.001) and travel medicine experience (+.365, p =.002). No significant correlation was found between precourse exam and area of specialty training. Combined mean score on the postcourse exam improved to 81.8% 6 4.5, an increase of 17.2% over the precourse score for those who took both tests (p <.001).

CONCLUSIONS

The profession of the provider and the duration of experience in travel medicine were the most important correlations of baseline knowledge in travel medicine. All groups improved their knowledge following the course.

Compliance of malaria chemoprophylaxis among travelers to India

BACKGROUND

Compliance is an important issue in malaria chemoprophylaxis. The objective of the study was to determine reasons for noncompliance with chemoprophylaxis among international travelers to India.

METHODS

A group of 452 subjects traveling in the subcontinent were interviewed by directly administered questionnaire at two selected locations in Calcutta during October 1992. Full compliance was defined as the uninterrupted use of drugs, as per the World Health Organization (WHO) schedule, during travel up to the date of interview.

RESULTS

Overall, the sample had a male preponderance (61%), with 155 (34%) being business travelers and 56% traveling for more than 3 weeks. Of the 158 (35%) reporting illness during travel, 5 persons tested positive for malaria. Compliance with chemoprophylaxis noted among 320 (71%) respondents in comparison to 21 (5%) found taking inadequate dosage or incorrect medication and 111 (24%) travelers being without any drugs. Backpackers and ethnic travelers as a group reported lower usage. Female, first visit and long-term travelers were less compliant. Inadequacy in pretravel advice, discontinuation due to side effects and active decision despite pretravel advice were common reasons for noncompliance. Past travel experience, concern for side effects, perceived uselessness and confusion arising from alternative regimens were also found to have influenced the decision making.

CONCLUSION

We need to address the identified areas of conflict especially during pretravel counseling since improving compliance is our primary goal in malaria prevention among travelers today.

The effect of chemoprophylaxis on the timing of onset of falciparum malaria

The association between chemoprophylaxis and delayed onset of falciparum malaria was investigated in a retrospective study of 477 nonimmune cases reported to the UK Malaria Reference Laboratory (MRL) who had used either mefloquine (n = 56), chloroquine-proguanil (n = 90) or no chemoprophylaxis (n = 331). For holiday and short-term travellers using mefloquine the time between arrival in the UK and diagnosis was found to be significantly longer than for chloroquine and proguanil (C-P) users or for those who had not used prophylaxis at all (P < 0.004). This delay was primarily due to a later onset of symptoms. C-P use was not associated with delay in onset of symptoms or diagnosis when compared to not using prophylaxis. Possible reasons for the findings are discussed. Mefloquine may continue to exert a partially suppressive effect on resistant strains of Plasmodium falciparum (Pf). That chloroquine with proguanil was not found to have such an effect may be due to poor compliance to proguanil or differences in the mode of action and range of parasite resistance to the two regimens. Differences in drug compliance may be one reason why only mefloquine users on holiday or short-term journeys experienced delays to onset of disease. Drug compliance amongst cases of breakthrough malaria on chemoprophylaxis may be lower than is generally recognized. It is important for clinicians and travellers to be aware that the onset of falciparum malaria may be delayed by mefloquine prophylaxis.

Primary health care needs for travel medicine training in Britain

BACKGROUND

In the UK, travel health advice is mainly provided by practice nurses and general practitioners (GPs). The need for their improved education in travel medicine has been highlighted through previous studies and by an increasing number of requests for training.

METHODS

A questionnaire-based survey of 3900 GP practices was conducted to assess training requirements and to establish the demand for an academic course in travel medicine. 1430 (37%) questionnaires were completed.

RESULTS

93% of practices provided a pretravel advice service. 87% of GPs advised an average of 10 travelers per month and only 48% immunized travelers. 98% of nurses advised and immunized an average of 28 travelers a month. 21% of GPs and two-thirds of nurses had attended one or more training sessions in travel medicine. Over 90% of the sample (83% of GPs and 98% of nurses) expressed an interest in attending a formal training program in travel medicine. Eligibility for Post Graduate Education Awards (PGEA) was important for most GPs (88%). Nurses valued approval by the English National Board for Nursing (88%) and a system of Credit Accumulation & Transfer (CATS) (82%). Funding for a course would be met in full by 18% of respondents (mainly GPs) and a further 20% would contribute to fees. Most GPs and nurses have ready access to a range of information sources, e.g., a postgraduate medical centre (85%) and a medical library (91%). Computerized access to information was feasible as 93% had a computer and 54% had a modem attached.

CONCLUSIONS

The discipline of travel medicine is becoming increasingly specialized. Future practitioners will need to enhance their skills to meet the demands of today's travelers. Our results show that general practice staff are keen to develop such skills. Specialist training courses need to be expanded to meet this demand.

Information about antimalarial chemoprophylaxis in hospitalised patients--is it adequate?

Malaria remains a huge public health problem worldwide, with over 100 million new cases annually, causing one to two million deaths. This global problem spills over into the UK, with around 2000 cases of reported annually. The proportion of infections due to Plasmodium falciparum (PF) continues to increase and worse still accounts for five to 12 deaths per year. In 1992, Nathwani et al reported the 10 year experience of malaria cases admitted to the Regional Infection Unit, in Aberdeen, Scotland--the "Oil Capital". This study was of interest in that 46% of those British residents who acquired infection had travelled to West or Central Africa on oil related business. The Oil boom of the 1980's appeared to very much centred around Aberdeen and the neighbouring hinterland but did not appear to extend to Dundee which was only 60 miles further down the North-East coast. We, therefore, carried out a retrospective study of patients with malaria admitted to the Regional Infectious Diseases Unit in Dundee over a fifteen year period between 1980 and 1994.

Malaria Chemoprophylaxis in German Tourists: A Prospective Study on Compliance and Adverse Reactions

Background: The number of tourists visiting malaria endemic regions is continuously increasing. The risk of aquiring malaria infection can largely be prevented by the regular use of chemoprophylactic drugs combined with using protective measures against mosquito bites. In a prospective study we wished to determine the tolerability of chemoprophylactic drugs and the factors that influence compliance with malaria chemoprophylaxis and antimosquito measures. Method: German travelers (n = 6504) who attended the Berlin Institute of Tropical Medicine in Berlin for pretravel medical advice were interviewed by phone 4 weeks after their journeys about compliance with the recommended malaria chemoprophylaxis and the incidence of side effects. Results: Compliance was better with mefloquine (94.5%) than with chloroquine (85.9%) (p<.001) or chloroquine plus proguanil (79.8%) (p<.001). Compliance was influenced by the purpose of travel, duration of stay, places of stay, and adverse reactions. Side effects occurred in 20.6% of the travelers who took chemoprophylactic drugs. There was no significant difference in the incidence of side effects between the three drug regimens, but people who took mefloquine more often reported neuropsychiatric reactions (6.5% versus 3.9% with chloroquine and 3.6% with chloroquine and proguanil; p<.001)). Side effects were usually mild to moderate and in no instance required hospitalization. People who took their drugs with meals less often reported side effects (15.2%) (p<.01). Conclusion: The knowledge of user profiles (and particular factors that presage side effects and noncompliance) may help us to improve pretravel counseling, thereby reducing the risk that travelers may acquire malaria infection.

Malaria and Casual Sex: What Travelers Know and How They Behave

Background: Travelers to the tropics have been reported to comply poorly with recommendations regarding malaria and AIDS. This study addresses the problem of influencing travelers' behavior through different approaches to conveying advice. Method: 3509 people attending a large travel clinic were randomly allocated to different interventions, including brochures about the implications of "sex tourism" and the possibility of participating in a contest assessing knowledge of malaria and AIDS. A comparison group (n = 607) of travelers to Kenya was contacted at an airport. Anonymous, self-administered questionnaires were sent to all travelers after their return. Results: Compliance with chemosuppressive regimen for malaria was 87%. Well-informed travelers did not protect themselves more efficiently against malaria. The efficacy of a given intervention was found to vary according to the age, sex, or travel experience of the participants. Of travelers, 51% reported casual sex abroad (M/F: 69/31). Thirty-eight percent of these contacts were unprotected. Casual sex abroad and condom use were correlated with a history of casual sex in the home country. Condom use was especially low in young women, who were also more likely to have casual sex with fellow travelers than with local partners. Eight percent of the "sex tourism" brochure readers had engaged in casual sex with local partners (all travelers, 4%). Conclusions: Lack of knowledge does not appear to be the problem. Travelers need to be motivated to put their knowledge into practice. Our results suggest that risks relating to malaria and AIDS are perceived in a different manner and that counseling should be individualized. Contest questions can help start a discussion on ethical and health-responsible behavior. The target group of the "sex tourism" brochure was reached, but their behavior appears not to have changed. Objective criteria can help physicians recognize "high-risk" travelers. Travelers need to be made aware that they may encounter environments conducive to risky behavior and that, while abroad, they may react in unexpected ways.

The pharmacokinetics of three multiple dose regimens of chloroquine: implications for malaria chemoprophylaxis

The pharmacokinetics of chloroquine were studied in healthy volunteers who received one of three different multiple-dose regimens for 3 weeks: once weekly 300 mg, twice weekly 200 mg and once daily 50 mg chloroquine. Plasma concentrations of chloroquine and metabolites were determined by h.p.l.c. with fluorescence detection. The concentration-time course was fitted to a multiple-dose pharmacokinetic model. Volume of distribution, elimination half-life and clearance were not different for the three regimens, ranging from 250-302 l kg-1, 374-479 h and 0.44-0.58 l h-1 kg-1 respectively. After the first week of all dosage regimens, peak and trough concentrations of chloroquine were above 16 micrograms l-1, sufficiently suppressive for chloroquine-sensitive P. falciparum strains. These data suggest that once daily chloroquine could be combined with proguanil in a single tablet and should improve compliance when given for malaria chemoprophylaxis.

Malaria in Aberdeen: an audit of 110 patients admitted between 1980-1991

All 110 patients seen in North East Scotland after contracting malaria from foreign travel were treated in the Regional Infection Unit in Aberdeen. Those patients managed there from January 1980 to March 1991 are described. There were 54 episodes of Plasmodium falciparum malaria (49%) and 26 episodes (23%) of Plasmodium vivax malaria. The remainder had either mixed infection or were diagnosed as malaria on high clinical probability. The majority of the patients were male (80%) and under 40 years of age (84%). Most patients were either caucasians born in the UK (69%) or native Africans (23%) who were students recently arrived for further education or who had returned from visiting their country of origin for summer holidays. The British residents acquired infection either while on oil related business in West or Central Africa (46%) or after travelling on holiday (30%). The peak incidence of presentation was August and September. 93.5% of patients with falciparum malaria had returned or originated from Africa. 42% with vivax malaria had visited Africa and 27% Papua New Guinea. 70% had been prescribed antimalarial prophylaxis but less than half of these took their medication correctly. The majority of patients with falciparum malaria presented within two weeks of arrival in Britain while patients with vivax malaria presented at varying (but generally longer) intervals, 42% being diagnosed more than three months after exposure. Falciparum infection was more severe although there have been no deaths in the unit from malaria. Our experience seemed of interest and worth reporting because of the number of patients whose infection reflected travel related to the off shore oil industry, which is centred in Aberdeen.

Travellers' malaria

The risk of malaria poses travellers and their advisers with difficult problems as drug resistance spreads worldwide. Protection against infection rests on travellers' knowledge of the risk of malaria, on their avoidance of malaria vectors and on their compliant use of chemoprophylaxis. In this article, Robert Ste f fen and Ronald Behrens explain that one of the priorities for reducing malaria morbidity is to improve travellers' use of personal protection against mosquito bites. They show that none of the drugs, or combinations thereof, provide a 100% efficacy, owing to increasing drug resistance, mainly of Plasmodium falciparum. The commonly used drugs for malaria prophylaxis (mefloquine, doxycycline, chloroquine and proguanil) often cause minor side effects. All, except proguanil, have also been occasionally associated with severe adverse effects. Other drugs (pyrimethaminelsul fadoxine, amodioquine) are not suitable for chemoprophylaxis because of unacceptable adverse reactions. The use of drugs for self therapy is constrained by limitations of toxicity and efficacy, and the added difficulties of defining indications for safe and appropriate use.

Health problems in Norwegians travelling to distant countries

373 travellers to countries outside Europe and North America were recruited before departure summer 1988 at the Vaccination Office, Trondheim, Norway, and participated in a follow-up study on health problems related to travel. 313 of the travellers (84%) responded by answering a postal questionnaire one month after return; it dealt with prophylactic measures, life-style, and health problems associated with travelling. An 18% failure in malaria prophylaxis and some risk-taking behaviour related to alcohol and sex were recorded. Diarrhoea (usually mild) was reported by 59%; other symptoms were also frequent. Medical advice was sought by 18% while abroad; 7% consulted a doctor. Ill health made travelling less enjoyable than expected for 8%. After return, 25% had health problems; 9% saw a doctor, three travellers were hospitalized, and 6% were absent from work. Total morbidity was high, but seldom serious. Targeted advice, which can well be given by primary health care personnel, could help to reduce morbidity and risk behaviour and improve travellers' handling of ill health.

Malaria prophylaxis in travellers to tropical Africa

This study investigated travellers to tropical Africa with regard to prophylactic treatment of malaria. A total of 5703 travellers completed a questionnaire on their flights back to the Federal Republic of Germany; 4116 passengers (73.7%) had visited East Africa, while 808 (14.5%) had been to West Africa. The results indicate that 90.2% took a regular chemoprophylaxis against malaria. Nevertheless, 8.1% of the travellers used no antimalarials and in 9.3% chemoprophylaxis was inadequate due to inappropriate advice; for example, 7.5% still took pyrimethamine-sulfadoxine as prophylactic. Mefloquine was correctly taken by 38.9% of the travellers in East Africa; 12.6% used it in West Africa where it is not necessary. Antimosquito measures have a high priority for travellers to tropical Africa and dissemination of this fact must be improved since only 72.6% followed through on such advice.

Malaria in Leicester 1983-1988: a review of 114 cases

We have reviewed 114 episodes of malaria in 110 patients who were admitted to the Infectious Diseases Unit in Leicester during the 5 year period from February 1983-January 1988. There were 71 episodes of vivax malaria (62%), 33 episodes of falciparum malaria (29%), four patients with mixed infection and six patients with negative blood films who were diagnosed on clinical suspicion alone. Most patients presented in the summer months, 68% were aged under 40 years, 39% were born in the Indian subcontinent, 23% in East Africa and 23% in Britain. Eighty-two per cent of patients with falciparum malaria had recently returned from Africa whereas 82% with vivax malaria had visited Asia. Thirty six per cent had been given antimalarial chemoprophylaxis but only half of these took medication correctly. Seventy five per cent of episodes of falciparum malaria presented within 2 weeks of arrival in Britain, however vivax malaria could present at any time and 49% of cases occurred over 3 months after exposure. Presenting symptoms and signs were often non-specific. Twenty nine per cent of patients had been treated with antibiotics and 11% received antimalarials prior to admission. Vivax malaria was generally a mild infection but falciparum malaria was often severe with 39% of patients experiencing complications including one death. Although Plasmodium vivax and P. falciparum are morphologically similar the diseases caused by the two species of parasite are quite distinct. Physicians must ensure that malaria is excluded in anyone who has travelled to an endemic area.

Malaria incidence and prevention among European and North American travellers to Kenya

A longitudinal survey was conducted among travellers departing from Nairobi airport to determine the use of malaria prevention measures and assess the risk for malaria while travelling in Kenya. Among 5489 European and North American travellers, 68 different drug regimens were used for prophylaxis, and 48% of travellers used both regular chemoprophylaxis and more than 1 antimosquito measure during travel; 52% of 3469 travellers who used chemoprophylaxis did so without interruption during their travel and for 4 weeks after departure. Compliance was lowest among travellers who visited friends and relatives, who were young, or who stayed more than 3 weeks. Sixty-seven (1%) travellers experienced symptoms of malaria, but the diagnosis could be verified for only 16 of these. Long-stay travellers appeared to be at higher risk for malaria than short-stay travellers, and health information needs to be targeted especially to the former. Similar investigations are needed among international travellers to other malaria-endemic countries. With comparable data available, consistent and effective malaria prevention guidelines can be developed.

Malaria prophylaxis in travellers from Britain

A short questionnaire about malarial prophylaxis was completed by 376 travellers departing from Gatwick Airport to destinations in Asia, Africa, Australasia and South or Central America. Only 263 (70%) had sought advice, 80% of them from a general practitioner. Of travellers born in Britain, 81% had sought advice compared to 38% of those born abroad (P less than 0.001). Advice about protective measures to reduce mosquito bites had been given to 52% travellers. Although 264 were travelling to areas where prophylaxis is advised, only 167 (63%) were taking antimalarials, while 22% travelling to malaria-free destinations were taking unnecessary prophylaxis. Many British travellers do not take effective antimalarial chemoprophylaxis. This has undoubtedly contributed to the recent increase in incidence of the disease in the U.K. General practitioners should ensure that they give correct advice and the immigrant population need to understand the risk of malaria when they return home.

Malaria--an overview

The epidemiology, clinical features, diagnosis, prognosis, management, chemotherapy and chemoprophylaxis of malaria are reviewed.

Malaria prophylaxis amongst British residents of Lilongwe and Kasungu districts, Malawi

Questionnaires on various aspects of malaria prophylaxis were distributed to all British residents (adults and children) of Lilongwe and Kasungu districts, Malawi, and were completed and returned by 293 (response rate 89%). Almost all residents used some measures to reduce mosquito contact, and 96% used chemoprophylaxis. Eight different chemoprophylactic regimens were used. Proguanil, alone or with chloroquine, was the most popular agent despite being associated with mouth ulcers in 25% of residents. Residents on this regimen had in general obtained their advice from a British source, and 75% considered they were adequately informed on the subject. This regimen was the most effective in preventing malaria attacks in the previous 12 months, even though over half those on proguanil alone were taking an inadequate dose. Residents on other chemoprophylactic regimens in general obtained their advice elsewhere, considered they were inadequately informed, and had a higher incidence of malaria. Whatever the regimen, 27% of adult residents would discontinue prophylaxis prematurely on return to the United Kingdom. Results suggest that more needs to be done to provide regular, precise and up-to-date information on malaria prophylaxis to British residents in malaria endemic areas.

Development of recommendations for the protection of short-stay travellers to malaria endemic areas: Memorandum from two WHO Meetings

In the past, since malaria chemoprophylaxis was assumed to be of benefit and with no serious complications, it was recommended to all travellers who were at risk of acquiring the disease. The current epidemiological situation of malaria is marked by the increasing spread of Plasmodium falciparum resistance to chloroquine and by problems due to the toxicity of other drugs. Recommendations for malaria prophylaxis should therefore be based on an epidemiological approach which takes into account the risk of acquiring the infection, the toxicity and effectiveness of the available antimalarial drugs, the traveller's perception of these risks, and the human factors that influence the use of all possible protective measures against malaria.This Memorandum describes the epidemiological approach and the data bases required for the development of recommendations on prophylaxis for short-stay visitors in malaria endemic areas, and gives guidelines on the protective measures and drugs that may be used in defined situations.