Falling rates of malaria among U.S. military service members in Afghanistan substantiate findings of high compliance with daily chemoprophylaxis

Rational Risk-Benefit Decision-Making in the Setting of Military Mefloquine Policy

Mefloquine is an antimalarial drug that has been commonly used in military settings since its development by the US military in the late 1980s. Owing to the drug's neuropsychiatric contraindications and its high rate of inducing neuropsychiatric symptoms, which are contraindications to the drug's continued use, the routine prescribing of mefloquine in military settings may be problematic. Due to these considerations and to recent concerns of chronic and potentially permanent psychiatric and neurological sequelae arising from drug toxicity, military prescribing of mefloquine has recently decreased. In settings where mefloquine remains available, policies governing prescribing should reflect risk-benefit decision-making informed by the drug's perceived benefits and by consideration both of the risks identified in the drug's labeling and of specific military risks associated with its use. In this review, these risks are identified and recommendations are made for the rational prescribing of the drug in light of current evidence.

Idiosyncratic quinoline central nervous system toxicity: Historical insights into the chronic neurological sequelae of mefloquine

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Regulators now warn adverse neurological effects from mefloquine may be irreversible.

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Many neurological effects resemble those of a common quinoline CNS toxidrome.

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The quinoline toxidrome is associated with a risk of CNS neuronal degeneration.

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CNS neuronal degeneration may underlie some neurological effects from mefloquine.

Mefloquine is a quinoline derivative antimalarial which demonstrates promise for the treatment of schistosomiasis. Traditionally employed in prophylaxis and treatment of chloroquine-resistant Plasmodium falciparum malaria, recent changes to the approved European and U.S. product labeling for mefloquine now warn of a risk of permanent and irreversible neurological sequelae including vertigo, loss of balance and symptoms of polyneuropathy. The newly described permanent nature of certain of these neurological effects challenges the conventional belief that they are due merely to the long half-life of mefloquine and its continued presence in the body, and raises new considerations for the rational use of the drug against parasitic disease. In this opinion, it is proposed that many of the reported lasting adverse neurological effects of mefloquine are consistent with the chronic sequelae of a well characterized but idiosyncratic central nervous system (CNS) toxicity syndrome (or toxidrome) common to certain historical antimalarial and antiparasitic quinolines and associated with a risk of permanent neuronal degeneration within specific CNS regions including the brainstem. Issues in the development and licensing of mefloquine are then considered in the context of historical awareness of the idiosyncratic CNS toxicity of related quinoline drugs. It is anticipated that the information presented in this opinion will aid in the future clinical recognition of the mefloquine toxidrome and its chronic sequelae, and in informing improved regulatory evaluation of mefloquine and related quinoline drugs as they are explored for expanded antiparasitic use and for other indications.

Risk assessment and prevention of malaria among Italian troops in Afghanistan, 2002 to 2011

BACKGROUND

Malaria prevention policy is different among coalition troops in Afghanistan, ranging from the combined use of suppressive and terminal chemoprophylaxis to the absence of any prophylactic regimen. The objective of this study was to assess the compliance with malaria prevention measures and the risk of malaria among Italian troops in Afghanistan.

METHODS

Target population was the cohort of 32,500 army soldiers deployed in Afghanistan, 2002 to 2011; eligible subjects were the 21,900 soldiers stationed in endemic areas, who were prescribed mefloquine chemoprophylaxis. Adherence to chemoprophylaxis was assessed by a cross-sectional study in a volunteer sample of 5,773 (26.4%) of eligible subjects. The risk of malaria was assessed by detecting malaria cases in the target population.

RESULTS

Mefloquine chemoprophylaxis was administered to 4,123 (71.4%) of the 5,773 enrolled soldiers and 3,575 (86.7%) of these took it regularly; however, compliance dropped from 80.9% (2,592/3,202) in 2002 to 2006 to 59.5% (1,531/2,571) in 2007 to 2011 (p < 0.01). Adverse events were reported by 875 (21.2%) of the 4,123 soldiers taking mefloquine, but caused irregularity or interruption of chemoprophylaxis only in 48 (1.2%) and 113 (2.7%) subjects, respectively. No serious adverse events were reported. No malaria cases occurred in Afghanistan, and one Plasmodium vivax case was reported in Italy, yielding an incidence rate of 3.24 cases per 10,000 person-months of exposure (1/3,091) during the transmission season of 2003.

CONCLUSIONS

In spite of the decreasing compliance with chemoprophylaxis, suggesting a low perception of the risk of malaria, this study confirmed the good tolerability of mefloquine in the military. The risk of malaria for Italian troops in Afghanistan was very low, and chemoprophylaxis was suspended in 2012. A similar policy may be adopted by the generality of International Security Assistance Force troops, and any chemoprophylaxis may be restricted to soldiers stationing in areas where the risk of malaria is substantial.