Sudden death in a traveler following halofantrine administration--Togo, 2000

On July 17, 2000, a previously healthy 22-year-old U.S. student collapsed and died suddenly while leading a teenage exchange group in West Africa. This report summarizes the results of the investigations of this incident, which implicate use of halofantrine for treatment of malaria as the cause of death. Travelers should be warned that halofantrine treatment may be dangerous in persons with cardiac abnormalities or in those taking mefloquine for malaria prophylaxis.

Acute respiratory distress syndrome complicating Plasmodium vivax malaria

Malaria is one of the most common infectious diseases in the world, and severe respiratory complications have been described mainly in association with Plasmodium falciparum. We describe a case of acute respiratory distress syndrome complicating infection with P. vivax in the setting of relatively low parasitemia in a 47-yr-old woman after a brief trip to Papua New Guinea. A review of the literature shows that pulmonary complications of P. vivax are rare but occur more frequently than generally acknowledged. Pathogenic mechanisms of these complications are discussed.

Drug resistant malaria on the Thai-Myanmar and Thai-Cambodian borders

We describe the changing epidemiology of drug resistant malaria in Thailand over the past decade. Factors determining the characteristic patterns of the development and spread of resistance to anti-malarial drugs on the Thai-Cambodian border and the Thai-Myanmar border are explored, namely, population dynamics, drug usage and malaria control measures. The introduction of artesunate-mefloquine combination in selected areas along the two borders in 1995 is believed to be one of the multiple factors responsible for stabilizing the multidrug resistance problems in Thailand today. Other control measures and inter-governmental co-operation must continue to be strengthened in order to limit the spread of drug resistance malaria in the Southeast Asian region.

The Italian army standpoint on malaria chemoprophylaxis

Soldiers on duty in tropical areas are at high risk of malaria and need chemoprophylactic regimens which may ensure the best efficacy, tolerability and compliance. Current Italian Army guidelines are based on recent military experiences in tropical areas, where mefloquine prophylaxis was as well tolerated as combination treatment with chloroquine and proguanil but more effective and easier to comply with, at least among soldiers. Chloroquine alone (300 mg base once/week) is prescribed for areas without chloroquine-resistant Plasmodium falciparum, while mefloquine (250 mg once/week) is recommended for areas with chloroquine-resistance. Doxycycline is the first choice regimen for mefloquine-resistant areas and an alternative to mefloquine when this medication is contraindicated or not tolerated. The combination chloroquine-proguanil represents the alternative chemoprophylactic regimen when mefloquine and doxycycline are contraindicated or not tolerated.

Preliminary assessment of the efficacy of mefloquine/-sulphadoxine/ pyrimethamine combination in the treatment of uncomplicated malaria in children in North Eastern Nigeria

Preliminary assessment of efficacy of mefloquine/-sulphadoxine/pyrimethamine (MSP) combination in the treatment of uncomplicated Plasmodium infections was conducted in-vivo in non-immune and semi-immune children in Damboa, in the North east of Nigeria using a 7-day protocol. Six hundred and forty-six (76.4%) subjects out of 846 screened had positive Plasmodium infections. Seventy-two patients aged 6 months to 11 years were enrolled, of whom 69 (95.8%) completed the study. MSP demonstrated high clinical efficacy, producing 100% cure rate against pure P. falciparum (77.8%), pure P. malariae (18.1%) and mixed P. falciparum and P. malariae (4.2%) infections. GMPDs for P. falciparum, P. malariae and mixed infections were 4,826, 3,680 and 12,573 a sexual stages per microl of whole blood. The mean parasite clearance time (MPCT) was 4.42 days for pure P. falciparum parasitaemia and 4.82 days for P. malariae alone. No parasitologic failure occurred in the patients. Clinical response occurred rapidly; all fever cases cleared within 24 hours. Moreover, significant (P<0.05) PCV improvement occurred in 7 days from an average of 33.8 +/- 4.5% on D0 to 35.5 +/- 3.5% on D7. Besides, this drug was well tolerated by majority of patients. Details of these findings are presented and discussed against the background of increased efforts towards effective malaria treatment and control in Nigeria.

Pregnancy and mefloquine prevention of malaria

(1) Mefloquine is teratogenic in animals at high doses. (2) A prospective cohort study of several hundred women exposed to mefloquine at prophylactic doses (250 mg per week) in early pregnancy showed no increased risk of malformations. (3) Exposure to mefloquine in early pregnancy is not an indication for termination. (4) Data on exposure during the second or third trimester are reassuring. According to the World Health Organisation (WHO), the risk-benefit ratio of mefloquine prophylaxis is favourable in pregnant women from the fourth month of pregnancy onwards in areas of group III chemoresistance. (5) In France, mefloquine is contraindicated throughout pregnancy. In other countries mefloquine is approved from the first trimester to cover unavoidable visits to areas of group III chemoresistance.

Randomized comparison of mefloquine-artesunate versus quinine in the treatment of multidrug-resistant falciparum malaria in pregnancy

Since no effective malaria prevention measures have been identified for pregnant women living on the western border of Thailand, prompt diagnosis and efficient treatment are paramount, although drug resistance in Plasmodium falciparum has narrowed the treatment options. An open randomized comparison of supervised quinine (10 mg salt/kg every 8 h) for 7 days (Q7) versus mefloquine 25 mg base/kg (total dose) plus artesunate 4 mg/kg per day for 3 days (MAS3) was conducted in 1995-97 in 108 Karen women with acute uncomplicated falciparum malaria in the second or third trimesters of pregnancy. The MAS3 regimen was more effective than the Q7 regimen: day 63 cure rates were 98.2% (95% CI 94.7-100) (n = 65) for MAS3 and 67.0% (95% CI 43x3-90x8) (n = 41) for Q7, P = 0x001. The MAS3 regimen was also associated with less gametocyte carriage; the average person-gametocyte-weeks for MAS3 was 2.3 (95% CI 0-11) and for Q7 was 46x9 (95% CI 26-78) per 1000 person-weeks, respectively (P < 0.001). MAS3 was significantly better tolerated. These evident advantages must be balanced against a possible increased risk of stillbirth with the use of mefloquine in pregnancy. Further randomized studies assessing the safety and efficacy of other artemisinin-containing combination regimens in pregnancy are needed urgently.

Treatment of malaria in north-eastern and south-eastern Nigeria: a population study of mefloquine, sulphadoxine, pyrimethamine combination (MSP) vs chloroquine (CQ)

In a population-based study involving 4019 patients in 20 peripheral health facilities in Nigeria, the outcome of presumptive malaria treatment with MSP was compared to that of CQ. The study was conducted between January 1995 and January 1996. Patients aged 6 months or more with a clinical diagnosis of malaria based on history of fever and axillary temperature > 37.5 degrees C were either treated with MSP (250 mg mefloquine, 500 mg sulphadoxine, and 25 mg pyrimethamine per tablet) or CQ (150 mg chloroquine base per tablet). The clinical cure rate was assessed by the disappearance of clinical signs and symptoms over a 7-day period. Tolerability was assessed by the incidence of adverse events (adverse drug reaction and intercurrent illness). The result shows that the clinical care rate of suspected malaria was 97.6% with MSP and 85.6% with CQ. The incidence of adverse event was 9.5% with MSP and 9.2% with CQ. The withdrawal rate was 2.0% with MSP and 5.0% with CQ; 3.5% of the patients in the CQ group withdrew due to adverse events compared to 0.47% with MSP. In conclusion it was observed that in addition to superior efficacy of MSP over CQ, fever clearance rate with MSP was comparable to that of CQ. The study also demonstrated that two tablets maximum dose of MSP is safe and effective in a large population of Nigeria malaria patients.

Artemether-lumefantrine for the treatment of multidrug-resistant falciparum malaria

The efficacy and safety of the 6-dose regimen of artemether-lumefantrine were assessed in an open randomized trial in children and adults presenting with acute, uncomplicated Plasmodium falciparum malaria in Thailand between November 1997 and March 1998. 200 patients were enrolled in 2 centres: 150 received artemether-lumefantrine (i.e., a median total dose of 9.6 mg/kg [interquartile range 8.7-10.7] and 57.9 mg/kg of lumefantrine [52.4-64.0]) and 50 the standard combination of artesunate (12 mg/kg over 3 d) and mefloquine (25 mg/kg). All patients had rapid initial clinical and parasitological responses. The 28 d cure rates were high: 97.7% (95% confidence interval [95% CI] 93.5-99.5%) for artemether-lumefantrine and 100% (95% CI 92.5-100%) for artesunate-mefloquine. The 6-dose regimen of artemether-lumefantrine was better tolerated than, and as effective as, artesunate-mefloquine, the current standard treatment in this area of multidrug-resistant P. falciparum malaria.

Malaria in Brazilian military personnel deployed to Angola

BACKGROUND

Malaria represents one of the most important infectious disease threats to deployed military forces; most personnel from developed countries are nonimmune personnel and are at high risk of infection and clinical malaria. This is especially true for forces deployed to highly-endemic areas in Africa and Southeast Asia where drug-resistant malaria is common.

METHODS

We conducted an outbreak investigation of malaria cases in Angola where a total of 439 nonimmune Brazilian troops were deployed for a 6-month period in 1995-1996. A post-travel medical evaluation was also performed on 338 (77%) of the 439 soldiers upon return to Brazil. Questionnaire, medical record, thick/thin smear, and serum anti-Plasmodium falciparum antibody titer (by IFA) data were obtained. Peak serum mefloquine (M) and methylmefloquine (MM) metabolite levels were measured in a subsample of 66 soldiers (42 cases, 24 nonmalaria controls) who were taking weekly mefloquine prophylaxis (250 mg).

RESULTS

Seventy-eight cases of malaria occurred among the 439 personnel initially interviewed in Angola (attack rate = 18%). Four soldiers were hospitalized, and 3 subsequently died of cerebral malaria. Upon return to Brazil, 63 (19%) of 338 soldiers evaluated were documented to have had clinical symptoms and a diagnosis of malaria while in Angola. In addition, 37 (11%) asymptomatically infected individuals were detected upon return (< 1% parasitemia). Elevated, post-travel anti-P. falciparum IFA titers (> or = 1:64) were seen in 101 (35%) of 292 soldiers tested, and was associated with a prior history of malaria in-country (OR = 3.67, 95% CI 1.98-6.82, p <.001). Noncompliance with weekly mefloquine prophylaxis (250 mg) was associated with a malaria diagnosis in Angola (OR = 3.75, 95% CI 0.97-17.41, p =.03) but not with recent P. falciparum infection (by IFA titer). Mean peak levels (and ratios) of serum M and MM were also found to be lower in those who gave a history of malaria while in Angola.

CONCLUSIONS

Malaria was a significant cause of morbidity among Brazilian Army military personnel deployed to Angola. Mefloquine prophylaxis appeared to protect soldiers from clinical, but not subclinical, P. falciparum infections. Mefloquine noncompliance and an erratic chemoprophylaxis prevention policy contributed to this large outbreak in nonimmune personnel. This report highlights the pressing need for development of newer, more efficacious and practical, prophylactic drug regimens that will reduce the malaria threat to military forces and travelers.

Effects of artesunate-mefloquine combination on incidence of Plasmodium falciparum malaria and mefloquine resistance in western Thailand: a prospective study

BACKGROUND

Worsening drug resistance in Plasmodium falciparum malaria is a major threat to health in tropical countries. We did a prospective study of malaria incidence and treatment in an area of highly multidrug-resistant P. falciparum malaria.

METHODS

We assessed incidence of P. falciparum malaria and the in-vivo responses to mefloquine treatment over 13 years in two large camps for displaced Karen people on the northwest border of Thailand. During this time, the standard mefloquine dose was first increased, and then combined artesunate and mefloquine was introduced as first-line treatment for uncomplicated P. falciparum malaria.

FINDINGS

Early detection and treatment controlled P. falciparum malaria initially while mefloquine was effective (cure rate with mefloquine [15 mg/kg] and sulphadoxine-pyrimethamine in 1985, 98% [95% CI 97-100]), but as mefloquine resistance developed, the cure rate fell (71% [67-77] in 1990). A similar pattern was seen for high-dose (25 mg/kg) mefloquine monotherapy from 1990-94. Since the general deployment of the artesunate-mefloquine combination in 1994, the cure rate increased again to almost 100% from 1998 onwards, and there has been a sustained decline in the incidence of P. falciparum malaria in the study area. In-vitro susceptibility of P. falciparum to mefloquine has improved significantly (p=0.003).

INTERPRETATION

In this area of low malaria transmission, early diagnosis and treatment with combined artesunate and mefloquine has reduced the incidence of P. falciparum malaria and halted the progression of mefloquine resistance. We recommend that antimalarial drugs should be combined with artemisinin or a derivative to protect them against resistance.

Therapeutic trial in experimental tegumentary leishmaniasis caused by Leishmania (Leishmania) amazonensis. A comparative study between mefloquine and aminosidine

One hundred and eighty-two male inbred C57/BL/6 mice were infected with 3 x 10(6) Leishmania (Leishmania) amazonensis promastigotes of the MHOM/BR/PH8 strain by means of a subcutaneous injection in the right ear. The animals were separated in three groups: 1) oral mefloquine hydrochloride treatment (16 mg/kg/day/10 days), 2) intramuscular aminosidine (Paromomycin) treatment (20 mg/kg/20 days) and 3) control. Twenty-six mice of each treated group were sacrificed, one at the end of treatment (nine weeks after inoculation), and one six weeks later (fifteen weeks after inoculation). Control Group animals were sacrificed at weeks six, nine and fifteen after inoculation. There was no significant difference between Group 1 (mefloquine) and Group 3 (control) subjects. Group 2 animals (aminosidine) presented the smallest differences of all, both at the end of the treatment and six weeks later. The histopato-logical parameters have shown the following findings: a) there was no significant difference between the mefloquine treated group and the control group; the group treated with aminosidine showed fewer of vacuolated macrophages than the control group, at week 9 (end of treatment). b) both at the end of treatment and six weeks later, evaluation of tissue necrosis and tissue fibrosis revealed no differences between the treated groups. It was found that six weeks after the end of treatment, mice in the control group presented significantly more severe degrees of fibrosis than mice in the other groups. It can be concluded that mefloquine showed limited therapeutic effect in this experimental model, whereas aminosidine had a significant effect. Nevertheless, neither of them resulted in cure of the lesions.

Clinical and neurophysiological study of the effects of multiple doses of artemisinin on brain-stem function in Vietnamese patients

The qinghaosu (artemisinin) group of drugs is the most important new class of antimalarials developed in the last fifty years. Although there has been no clinical evidence of neurotoxicity, an unusual pattern of damage to specific brain-stem nuclei has been reported in experimental animals receiving high doses of arteether or artemether. Detailed clinical examinations, audiometry, and brain stem auditory evoked potentials (BSAEPs) were assessed in 242 Vietnamese subjects who had previously received up to 21 antimalarial treatment courses of artemisinin or artesunate alone and 108 controls from the same location who had not received these drugs. There was no evidence of a drug effect on the clinical or neurophysiological parameters assessed. In this population there was no clinical or neurophysiological evidence of brain-stem toxicity that could be attributed to exposure to artemisinin or artesunate.

Mefloquine-resistant strains of Plasmodium falciparum in Madagascar: impact on tourists and public health

Although the national policy for malaria control in Madagascar is to use chloroquine as the first line of treatment, mefloquine has been and is recommended to travellers to the country, both for malaria prevention and cure. The in-vitro susceptibility of Plasmodium falciparum to mefloquine was therefore assessed during a prospective surveillance study in various areas in Madagascar, including the tourist sites of Nosy-be and Sainte Marie. Of the 254 isolates of P. falciparum successfully tested, 232 (90.9%) were sensitive to mefloquine, 12 (4.7%) showed decreased susceptibility (40 nM < IC50 < 50 nM), and 10 (3.9%) were resistant (IC50 > 50 nM). Five (50%) of the resistant strains and nine (75%) of those with decreased susceptibility were from coastal areas or the two tourist sites. The drug pressure that could have induced the resistance observed could therefore be related to the donation of antimalarials, such as mefloquine, by tourists to local populations. The residents of the coastal areas take any donated drugs as self-medication, ignoring recommended doses and durations of treatment. This situation has two main consequences: (1) there is an urgent need to control the abusive and incorrect use of antimalarial drugs in Madagascar, to safeguard the effectiveness of chemotherapy in the future; and (2) these increases in resistance compromise the efficiency of the antimalarial chemoprophylaxis currently recommended to tourists. The use of mefloquine can no longer be considered as a guarantee of protection against malaria in coastal areas and other sites frequented by tourists.

Treatment of uncomplicated Plasmodium falciparum malaria in Myanmar: a clinical decision analysis

This study was undertaken to compare cost-effectiveness of three drug regimes for treatment of uncomplicated falciparum malaria in Myanmar. The alternative regimens in this study were chloroquine (CQ), sulphadoxine-pyrimethamine (SP) and mefloquine (MFQ) along with their therapeutic efficacy in Myanmar. The study was performed by modeling a clinical decision tree based on a hypothetical 1,000 adult uncomplicated falciparum malaria cases. Key variables were (i) three drug regimes: CQ, SP and MFQ, (ii) three categories of therapeutic efficacy of each drug: adequate clinical response (ACR), early treatment failure (ETF) and late treatment failure (LTF) according to the 1996 WHO protocol, and (iii) compliance with each drug. In structuring the model, necessary assumptions were made. The cost effectiveness was measured as cost per case cured and cost per case prevented death related to the provided drug, from the provider's perspective. According to the present price and therapeutic efficacy, SP is the most cost effective drug for a case cured in all three categories of efficacy (US$ 0.12 per case cured in ACR, US$ 0.38 per case cured in ETF and US$ 0.54 per case cured in LTF). For a case prevented death, CQ is most cost effective in all three categories (US$ 0.58 per case prevented death in the ACR, US$ 2.14 per case prevented death in the ETF and US$ 2.51 per case prevented death in the LTF). The lowest cost effective regimen is MFQ for both indicators of effectiveness at the present price and therapeutic efficacy. A sensitivity analysis was performed for sensitive values.

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.

Adaptation of a chloroquine-resistant strain of Plasmodium vivax from Indonesia to New World monkeys

The spread of chloroquine-resistant Plasmodium vivax from Papua New Guinea and Indonesia poses a serious health threat to areas of Southeast Asia where this species of malaria parasite is endemic. A strain of P. vivax from Indonesia was adapted to develop in splenectomized Aotus lemurinus griseimembra, Aotus vociferans, Aotus nancymai, and Saimiri boliviensis monkeys. Transmission to splenectomized Saimiri monkeys was obtained via sporozoites. Chemotherapeutic studies indicated that the strain was resistant to chloroquine and amodiaquine while sensitive to mefloquine. Infections of chloroquine-resistant P.vivax in New World monkeys should be useful for the development of alternative treatments.