Efficacy and safety of atovaquone-proguanil in treating imported malaria in Japan: the second report from the research group

Retrospective observational study of the use of artemether-lumefantrine in the treatment of malaria in Japan

BACKGROUND

The Research Group on Chemotherapy of Tropical Diseases, Japan, introduced artemether-lumefantrine (AL) in late 2002, mainly for treating uncomplicated Plasmodium falciparum malaria. Because AL was on the market in Japan in March 2017, the effectiveness and safety of AL were analyzed to help medical personnel use AL optimally.

METHODS

Case report forms submitted by the attending physicians were analyzed. When necessary, direct contact with the attending physicians was made to obtain detailed information.

RESULTS

Effectiveness analysis was performed for 62 cases and safety analysis was performed for 66 cases. In P. falciparum malaria, the overall cure rate was 91.1% (51/56), of which the cure rates for Japanese and non-Japanese patients were 82.1% (23/28) and 100% (28/28), respectively. The successfully treated cases included severe P. falciparum malaria, with parasite densities exceeding 500,000/μL. Adverse events were reported in 14 patients, including delayed hemolytic anemia which occurred in the top four highest parasitemic cases.

CONCLUSIONS

AL treatment failure in P. falciparum malaria may not be rare among non-immune individuals, including Japanese. The possibility of delayed hemolytic anemia, which occurs preferentially in high parasitemic cases, should be considered following AL treatment.

Imported malaria in pregnant women experienced in Japan

INTRODUCTION

With ever-growing global exchanges, the number of travelers, including pregnant women, to the tropics is increasing, which poses a risk of contracting malaria. Although there are several reports on imported malaria in pregnancy from Western countries, those focusing on cases experienced in Japan are very limited.

METHODS

We searched for cases of malaria in pregnancy in the treatment records submitted to the Research Group on Chemotherapy of Tropical Diseases, Japan, during the period 1993-2016. Literature searches were also conducted using an American and a Japanese search system.

RESULTS

Ten cases of malaria in pregnant women were identified, including four cases with Plasmodium falciparum. Of eight evaluable cases, only one practiced malaria chemoprophylaxis. Among the nine evaluable cases, eight resulted in uneventful delivery and one P. falciparum case developed severe hepatic disturbance, disseminated intravascular coagulation, and intrauterine fetal death. After the initial attack, none of the Plasmodium vivax/Plasmodium ovale cases practiced chloroquine prophylaxis until delivery. One P. ovale case received a lower dose regimen of chloroquine as acute-stage therapy.

CONCLUSION

This study demonstrated additional cases of imported malaria in pregnant women to the literature and highlighted various epidemiological, demographic, and clinical characteristics. Some of the clinical issues raised need to be investigated. Due to the paucity of the cases worldwide, sharing information among various countries is indispensable, and international guidelines which are now increasingly recommending the use of artemisinins in pregnant women should be referred.

Optimal primaquine use for radical cure of Plasmodium vivax and Plasmodium ovale malaria in Japanese travelers--A retrospective analysis

BACKGROUND

Recently, a dose of 30 mg (base) primaquine daily for 14 days is increasingly recommended for radical cure of Plasmodium vivax malaria. However, total primaquine doses, or those per body weight, are also recognized as important. In Japan, primaquine is not a licensed medicine, but has been used through the Research Group on Chemotherapy of Tropical Diseases for >3 decades.

METHODS

Based on clinical records submitted to the Research Group, patients with P. vivax and Plasmodium ovale malaria treated with primaquine were analyzed to determine the efficacy and safety of the antimalarial drug.

RESULTS

Seventy-five P. vivax cases, including 3 in children, and 19 P. ovale cases were enrolled. Five of the P. vivax cases demonstrated at least one relapse despite primaquine therapy. Total primaquine doses per body weight were obtained in 4 of the 5 relapsed patients, presenting 9 malaria episodes totally, and most of the primaquine failures were caused with a total dose ≤ 3.5 mg/kg. Liver function disturbance was reported in 2 cases.

CONCLUSION

In order to optimize radical cure of P. vivax, the total primaquine dose per body weight should be considered, at least 3.5 mg/kg or even more if contracted in countries with significant drug resistance. Possibility of primaquine hepatotoxicity in chronic liver disease patients remains to be elucidated.

Mixed-species Plasmodium falciparum and Plasmodium ovale malaria in a paediatric returned traveller

Malaria is a common and potentially fatal cause of febrile illness in returned travellers. Endemic areas for different malaria parasites overlap, but mixed species infections are rare. An adolescent male returned from a trip to Ghana in late summer 2013. He subsequently presented with blood smears positive for two species of malaria parasite, Plasmodium falciparum and Plasmodium ovale, on two isolated hospital visits within a six-week period. The epidemiology of mixed infections, likely pathophysiology of his presentation, and the implications for malaria testing and treatment in returned travellers are discussed.

Efficacy and safety of paromomycin for treating amebiasis in Japan

The clinical management of amebiasis is a growing concern, particularly among human immunodeficiency virus (HIV)-infected individuals who are predisposed to severe illness. Treatment with a luminal amebicide is strongly recommended following acute-stage treatment with a nitroimidazole. In 2004, the Japanese Research Group on Chemotherapy of Tropical Diseases introduced paromomycin, which was not nationally licensed, and offered it to a number of patients. From 2004 to 2011, 143 case records of amebiasis (123 with amebic colitis, 16 with amebic liver abscess, and 4 with both) in which patients were treated with paromomycin, mainly 1,500 mg/day for 9 or 10 days following metronidazole treatment, were submitted. Among 123 evaluable cases, 23 (18.7%) experienced possible adverse effects, the most common being diarrhea (17/123, 13.8%) and other gastrointestinal problems that were resolved after the completion or discontinuation of treatment. In addition, single cases of bloody stools associated with Clostridium difficile colitis, skin rash, and the elevation of liver enzymes were also reported, although the causal relationship was not clear. HIV infection did not appear to increase the incidence of adverse drug effects. Each of the 11 asymptomatic or mildly symptomatic amebic colitis cases became negative for stool cysts after paromomycin treatment. Paromomycin was shown to be safe and well tolerated, as well as effective in a special subset of amebic colitis cases.