Compliance with antimalarial chemoprophylaxis and the subsequent development of malaria: a matched case-control study

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.

Adherence to chemoprophylaxis and Plasmodium falciparum anti-circumsporozoite seroconversion in a prospective cohort study of Dutch short-term travelers

Background

We conducted a prospective study in a cohort of short-term travelers assessing the incidence rate of anti-circumsporozoite seroconversion, adherence to chemoprophylaxis, symptoms of malaria during travel, and malaria treatment abroad.

Methods

Adults were recruited from the travel clinic of the Public Health Service Amsterdam. They kept a structured daily travel diary and donated blood samples before and after travel. Blood samples were serologically tested for the presence of Plasmodium falciparum anti-circumsporozoite antibodies.

Results

Overall, the incidence rate (IR) of anti-circumsporozoite seroconversion was 0.8 per 100 person-months. Of 945 travelers, 620 (66%) visited high-endemic areas and were advised about both chemoprophylaxis and preventive measures against mosquito bites. Most subjects (520/620 = 84%) took at least 75% of recommended prophylaxis during travel. Travel to Africa, use of mefloquine, travel duration of 14–29 days in endemic areas, and concurrent use of DEET (N,N-diethyl-meta-toluamide) were associated with good adherence practices. Four travelers without fever seroconverted, becoming anti-circumsporozoite antibody-positive. All four had been adherent to chemoprophylaxis; two visited Africa, one Suriname, one India. Ten subjects with fever were tested for malaria while abroad and of these, three received treatment. All three were adherent to chemoprophylaxis and tested negative for anti-circumsporozoite antibodies.

Conclusion

Travel to Africa, using mefloquine, travel duration of 14–29 days in endemic areas, and use of DEET were associated with good adherence to chemoprophylaxis. The combination of chemoprophylaxis and other preventive measures were sufficient to protect seroconverting travelers from clinical malaria. Travelers who were treated for malaria abroad did not seroconvert.

Chemoprophylaxis and malaria death rates

Malaria chemoprophylaxis increases the survival of nonimmune travelers.

To determine the effect of chemoprophylaxis on the case-fatality rate of malaria, we analyzed all cases of Plasmodium falciparum malaria in nonimmune persons reported from 1993 to 2004 in Germany. In univariate and multivariate logistic regression analysis, we determined the effect of age, sex, chemoprophylaxis, chemoprophylactic regimen, compliance for chemoprophylactic regimen, exposure prophylaxis, country of infection, and year of reporting on the outcome. Of 3,935 case-patients, 116 (3%) died of malaria. Univariate analysis showed significant associations with death for chemoprophylaxis with chloroquine plus proguanil compared to no chemoprophylaxis. The multivariate model showed that patients who had taken chemoprophylaxis were less likely to die compared to those who had not taken chemoprophylaxis, adjusted for patient age and reporting year. The study demonstrated that chemoprophylaxis significantly reduced fatality rates among nonimmune malaria patients and supports the importance of existing guidelines for malaria prevention.

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.

Preparing for international medical service

In many ways, preparation for medical service outside the United States is not greatly different from preparation for a self-guided vacation tour of another country. The major differences are in the rigor that one should apply to being sure all details are set, particularly if one is planning to go to a site away from a capital city. Additionally, the mental preparation is required in terms of the understanding of global health issues in a holistic sense and the personal mental preparation for working under what may be austere conditions. With solid preparation, anyone interested in IH experiences should be able to have a rewarding, trouble-free experience.

Epidemiology of malaria presenting at British Columbia's Children's Hospital, 1984-2001: lessons for prevention

BACKGROUND

Few studies have examined the epidemiology of imported malaria in Canadian children. Identifying populations at increased risk in Canada would enable targeted malaria prevention strategies within those groups. The study objective was to describe the epidemiology of malaria diagnosed at British Columbia's Children's Hospital (BCCH) between 1984 and 2001.

METHODS

This was a retrospective chart review of malaria cases identified at BCCH and confirmed through the British Columbia Centre for Disease Control. Demographic and clinical data were recorded on a standardized form.

RESULTS

Malaria was diagnosed 42 times in 40 children (age 24 days to 14.8 years). Thirty cases (71.4%) occurred in 28 Canadian residents, and 12 (28.6%) occurred in immigrant or refugee children. Twenty-six children (65%) were male. Thirty-one children (77.5%) were of East Indian descent. Thirty-three exposures (78.6%) to malaria occurred in the Indian subcontinent. Plasmodium vivax was identified in 37 cases (88.1%), P. falciparum in 3 (7.1%), and the species was unknown in 2 (4.8%). Fourteen cases in the resident children (46.7%) reported pre-travel counselling. Ten resident cases (33.3%) were prescribed chemoprophylaxis, primarily chloroquine, and at least six of them (60%) were non-compliant. The duration of symptoms prior to diagnosis was < 7 days in 27 cases (64.3%), 8 to 30 days in 10 (23.8%), > 30 days in 4 (9.5%) and the duration was unknown in 1 (2.5%). Twenty-four of 36 cases (66.7%) had seen 2 to more than 4 doctors before the diagnosis of malaria was made.

CONCLUSION

The majority of children in our review were of East Indian origin and were exposed to malaria in India. Most had not sought or had received inadequate pre-travel counselling and had been non-compliant with chemoprophylaxis. As malaria is a potentially lethal but preventable disease, strategies to ensure adequate pre-travel counselling for high-risk groups are required.

Malaria epidemics and surveillance systems in Canada

In the past decade, fluctuations in numbers of imported malaria cases have been seen in Canada. In 1997 to 1998, malaria case numbers more than doubled before returning to normal. This increase was not seen in any other industrialized country. The Canadian federal malaria surveillance system collects insufficient data to interpret these fluctuations. Using local (sentinel), provincial, federal, and international malaria surveillance data, we evaluate and interpret these fluctuations. Several epidemics are described. With an ever-increasing immigrant and refugee population of tropical origin, improved surveillance will be necessary to guide public health prevention policy and practice. The Canadian experience is likely to be generalizable to other industrialized countries where malaria is a reportable disease within a passive surveillance system.

Antimosquito precautions and medical chemoprophylaxis in French children with malaria

BACKGROUND

France is the European country with the highest number of imported malaria cases (7,500 in 2000). The aim of this prospective study was to evaluate the nature and efficacy of prophylactic measures in children under 15 years of age referred for malaria.

METHODS

Post travel questionnaires were given to the parents of malarial children in the emergency room. The study took place in two university hospitals in Marseilles, southern France, from August to October 2001.

RESULTS

Eighty-eight children under 15 years of age were included in this 3-month period. Most of them had been infected in Comoro archipelago. Almost two-thirds used bed nets, but only 47% did so every night. Sprayed bed nets were used by 23%. Average compliances with cutaneous repellents, bedroom repellents and long-sleeved clothing were 32%, 24% and 26%, respectively. Air conditioners were uncommon. Only 22% of the children used chemoprophylaxis correctly, according to French recommendations. Five percent did not use any chemoprophylaxis, and 61% reported non recommended drug use. Although all the children traveled to chloroquine-resistant areas, chemoprophylaxis with mefloquine was less common than that with chloroquine + proguanil. No child fully complied with French recommendations concerning both anti mosquito measures and chemoprophylaxis.

CONCLUSIONS

Insufficient use of antimalaria precautions by traveling families is associated with the high incidence of pediatric imported malaria in southern France. Travelers' education should be increased to allow the optimization of malaria prophylaxis.

Self-reported compliance with last malaria treatment and occurrence of malaria during follow-up in a Brazilian Amazon population

The objective of this study was to describe the association between self-reported compliance with last malaria treatment (CMT) and occurrence of malaria during follow-up, controlling for current risk factors. We conducted a prospective open cohort study in Leonislândia, a rural area of Peixoto de Azevedo City, in the Amazon region of Mato Grosso, Brazil. A total of 414 individuals were interviewed at baseline regarding CMT and followed-up for either 8 or 4 months to assess malaria incidence. The associations between CMT and occurrence of malaria were examined through multiple linear regression (when the outcome was malaria episode frequency) or Cox regression (when the outcome was time to malaria onset). Poor CMT (prior to baseline) was identified as an important predictor of the occurrence of subsequent malaria episodes during follow-up among individuals with an indication of being less immune - those whose first malaria episode was relatively recent or those who had an increased number of malaria episodes during the last 2 years. Moreover, surprisingly, it seems that for individuals who are probably more immune (individuals who had experienced their first malaria episode more than 4.5 years previously or those with few or no malaria episodes during the last 2 years), CMT was found to be a poor predictor of increased risk of subsequent malaria. These findings provide compelling evidence for the need to further study CMT and its effect on malaria outcomes.

Problems in prescribing malaria chemoprophylaxis for travelers

To offer effective malaria chemoprophylaxis for travelers in a country, the physician must know the precise status of malaria there (frequency, resistance), determine the degree of exposure to mosquito bites, evaluate the precise clinical condition of the traveler, and improve the traveler's compliance with treatment by providing good information on potential side-effects. These side-effects, sometimes overemphasized in the media, lead to poor compliance, particularly after returning home, and, consequently, increase the risk of acquiring malaria. The recently approved Malarone could overcome these drawbacks. But its cost is high and its wide use could also lead to the emergence of resistant strains. Therefore, training professionals in travel medicine is important in malaria prevention and decrease the prescription of abusive or inaccurate prophylaxis (e.g., most tourists traveling in organized tours in Asia, with no stay in remote malaria endemic areas, do not need any prophylaxis). In addition, prevention of mosquito bites with repellents, impregnated bed nets, and indoor insecticide-dispensing devices is still an important tool for controlling malaria in travelers.

The prevention of malaria

Long before the advent of modern chemoprophylaxis drugs, many practitioners successfully prevented the debilitating and fatal outcomes associated with infection by the Plasmodium parasites that cause malaria. Today, with effective insect repellents and several excellent medications available for chemoprophylaxis, there has never been a better array of quality products to prevent mosquito bites and infection and to suppress parasites once in the blood stream; however, there are thousands of imported cases into nonendemic countries and scores of deaths and near-fatal outcomes every year in returning travelers, soldiers, immigrants, and refugees. In this article, the author focuses on practical uses of currently available prevention tools.

Incidence and precipitating factors of morbidity among Israeli travelers abroad

BACKGROUND

During recent years international travel, including visits to the developing world, has become increasingly popular. Many of these travelers suffer from some sort of health problem during their trip or after their return. Travelers clinics that give pretravel immunization and counseling have emerged. This study analyzes the incidence and risk factors for health problems among Israelis traveling abroad.

METHODS

The study surveyed by telephone 200 people who visited the traveler's clinic at Soroka Medical Center in Beer-Sheva during the years 1998 to 1999. The travelers were questioned after returning from their journey about the type and duration of the trip, compliance with medical advice given in the travel clinic, and health problems during the trip.

RESULTS

The mean age was 26.4 +/- 9.4 years, 7% went on an organized tour, 23% traveled alone, and 77% traveled with a friend. The mean duration of the trip was 14.7 +/- 13.4 weeks. Of the travelers, 70% reported some health impairment. Problems reported most frequently were gastrointestinal tract diseases (43%), respiratory tract diseases (25%), and injuries (10%). Only 4% were admitted to a hospital during their trip. After their return, 19.5% consulted a physician. Comparing the group of travelers who were sick with the rest, a correlation between noncompliance with the keeping of food hygiene and illness was found (p =.008). Additional risk factors for illness were long duration (p <.001), solitary trip (p =.04), and young age (p <.001). Of the people who were advised to take antimalaria chemoprophylaxis, 55% reported regular use of these drugs. Compliance with treatment correlated with older age (p <.001), short duration of stay (p =.01), previous experience, and travel to Africa (p <.001).

CONCLUSIONS

Most of the travelers to developing countries are young, travel for long periods, and live in basic conditions during their stay abroad. For these reasons travelers are at increased risk for morbidity. High risk travelers should be identified and counseled in order to increase their compliance with the medical advice and immunizations. A screening program for returning travelers should be considered.

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.

Low frequency of complications in imported falciparum malaria: a review of 222 cases in south-eastern Norway

We performed a retrospective study of 222 cases of falciparum malaria diagnosed in Oslo and Akerhus counties, Norway, from January 1988 to December 1997. Except for 12 cases, all had acquired the disease in sub-Saharan Africa. Sixty-four (28.8%) cases occurred in assumed non-immune individuals; of these, 41 (64.1%) were compliant to recommended antimalarial chemoprophylaxis. The mean time lag from first symptom to diagnosis (total diagnosis delay) was 4.6 d (median 3 d, range 0-30 d) and the mean time from presentation to diagnosis (doctor's delay) was 1.3 d (median 0 d, range 0-25 d). There were no fatal cases, and only 8 (3.6%) had a complicated course. The following factors were significantly associated with development of complicated disease: higher age, non-immunity combined with chemoprophylaxis non-compliance, prolonged doctor's delay and prolonged total diagnosis delay (p < or = 0.05). Our data suggest that complicated disease in imported falciparum malaria may largely be prevented by high chemoprophylaxis compliance rates in non-immune travellers and a high index of suspicion in physicians evaluating febrile travellers.

Clinicoepidemiological study of imported malaria in travelers and immigrants to Madrid

BACKGROUND

The number of Spanish travelers visiting malaria endemic areas, and the number of immigrants from malarial countries arriving in Spain are continuously increasing. However, little information about imported cases in Spain is available.

METHODS

A prospective clinicoepidemiological study of imported cases of malaria diagnosed at a referral teaching hospital in Madrid, Spain.

RESULTS

Of the 160 patients, sixty (37.5%) were immigrants and 100 (62.5%) Spanish nationals. Malaria was acquired in Africa by 98.3% of immigrants and in 83.0% of travelers. Falciparum malaria accounted for 71.8% of the cases, P. vivax for 11.9%, P. ovale for 10.6% and P. malarie for 5. 0%. Eleven (6.9%) patients, all immigrants, were asymptomatic. Severe complications were recorded in 17 (10.6%): 7, severe anemia; 3, cerebral malaria; 2, renal failure; 1, spontaneous splenic rupture; 1, acute pulmonary edema; 1, sepsis; 1, acute cerebrovascular accident; and 1, disseminated intravascular coagulation. There were no fatal cases. Among the 100 Spanish nationals, 44% did not follow any prophylaxis, 29% followed a correct prophylaxis, 27% were considered defaulters, and 39% took self-treatment without cure.

CONCLUSIONS

There is a changing pattern of imported malaria in Madrid, with one third occurring in immigrants and two thirds in nationals. This data provides information about the reemergence of imported malaria to Europe.

Malaria chemoprophylaxis of 3,446 French travelers departing from Paris to eight tropical countries

BACKGROUND

Each year more and more French travelers are visiting areas where malaria is endemic. The aim of this study was to assess prophylactic regimens used by French travelers and to determine whether they meet current published recommendations.

METHODS

This 12 month transversal study (May 1, 1995 to April 31, 1996) was conducted in embarkment lounges of Roissy Charles de Gaulle Airport to eight "tropical" destinations.

RESULTS

3,446 French travelers were enrolled. Twenty two and three-fifths percent of travelers had not sought any advice. The percentages of travelers staying less than 3 months (n = 2899) at risk of malaria (i.e., using none or inadequate chemoprophylaxis) were, according to the destination: Brazil (20%), Gabon (83%), Ivory Coast (26%), Kenya (43%), Madagascar (39%), Thailand (22%), Venezuela (41%) and Vietnam (8%). The suitability of the prophylaxis according to the information source for travelers staying less than 3 months varied as follows: specialist physician (OR = 1), travel agent (OR = 1.01, CI = 0.9 - 1. 1), occupational physician (OR = 1.13, CI = 0.6 - 2.1), GP (OR = 1. 58, CI = 1.1 - 2.3), none (OR = 1.95, CI = 1.3 - 2.9), friends (OR = 3, CI = 1.8 - 5) and pharmacist (OR = 3.94, CI = 2.1 - 7.5). Suitability of prophylaxis also varied according to the type of trip: organized tour (OR = 1), business trip (OR = 1.04, CI = 0.8 - 1.4), adventure tourism (OR = 2.1, CI = 1.6 - 2.9) and visit to family or friends (OR = 2.3, CI = 1.7 - 3.1).

CONCLUSIONS

This study shows that the quality of advice on antimalarial chemoprophylaxis varies markedly according to the source, and that nearly one in three French travelers (29.3 %, 850/2899) to tropical areas is at risk of malaria.

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.

A week in the life of a travel clinic

International travel has increased enormously in recent years. With the greater movement of people have come increased encounters with a wide variety of diseases: malaria, dengue, cholera, typhoid fever, Ebola virus, and many more. The need for greater scope, consistency, and knowledgeability in pretravel health care to meet these challenges has been met by the emergence of the discipline of travel medicine. Travelers are well advised to become informed of the risks they face and to take steps to minimize those risks. After reviewing a traveler's medical history and a detailed itinerary, a travel medicine practitioner can offer expert advice on behavioral modifications, immunizations, and chemoprophylaxis regimens which will increase the traveler's margin of safety. The issues most frequently addressed in a travel clinic include treatment of traveler's diarrhea, malaria chemoprophylaxis, and immunizations, for hepatitis A, typhoid fever, tetanus/diphtheria, influenza, pneumococcus, hepatitis B, polio, meningococcus, measles, mumps, rubella, varicella, and rabies. Pretravel consultation must consider the age and underlying health problems of the traveler, the nature of the trip (wilderness, jungle, rural, urban, resort, or cruise), the duration of travel, and the latest available information on the site in terms of disease outbreaks, terrorism, and natural calamities.