A Case of Recrudescence Plasmodium falciparum Malaria Treated with Atovaquone-Proguanil

Malaria is a potentially life-threatening disease caused by infection with the Plasmodium protozoa transmitted by an infective female Anopheles mosquito. Despite successful control programs in many countries, malaria remains to be a major disease burden worldwide, with approximately 584,000 deaths annually. The incidence of the disease and responsible species may differ due to increased human movements between countries. Plasmodium falciparum infection carries a poor prognosis with a high mortality if untreated, but it has an excellent prognosis if diagnosed early and treated appropriately. In the present study, we described a patient diagnosed with falciparum malaria and treated with atovaquone-proguanil who had a history of traveling to Uganda.

Abbreviated atovaquone-proguanil prophylaxis regimens in travellers after leaving malaria-endemic areas: A systematic review

BACKGROUND

We evaluated existing data on the prophylactic efficacy of atovaquone-proguanil (AP) in order to determine whether prophylaxis in travellers can be discontinued on the day of return from a malaria-endemic area instead of seven days after return as per currently recommended post-travel schedule.

METHODS

PubMed and Embase databases were searched to identify relevant studies. This PROSPERO-registered systematic review followed PRISMA guidelines. The search strategy included terms or synonyms relevant to AP combined with terms to identify articles relating to prophylactic use of AP and inhibitory and half-life properties of AP. Studies considered for inclusion were: randomized controlled trials, cohort studies, quasi-experimental studies, open-label trials, patient-control studies, cross-sectional studies; as well as case-series and non-clinical studies. Data on study design, characteristics of participants, interventions, and outcomes were extracted. Primary outcomes considered relevant were prophylactic efficacy and prolonged inhibitory activity and half-life properties of AP.

RESULTS

The initial search identified 1,482 publications, of which 40 were selected based on screening. Following full text review, 32 studies were included and categorized into two groups, namely studies in support of the current post-travel regimen (with a total of 2,866 subjects) and studies in support of an alternative regimen (with a total of 533 subjects).

CONCLUSION

There is limited direct and indirect evidence to suggest that an abbreviated post-travel regimen for AP may be effective. Proguanil, however, has a short half-life and is essential for the synergistic effect of the combination. Stopping AP early may result in mono-prophylaxis with atovaquone and possibly select for atovaquone-resistant parasites. Furthermore, the quality of the studies in support of the current post-travel regimen outweighs the quality of the studies in support of an alternative short, post-travel regimen, and the total sample size of the studies to support stopping AP early comprises a small percentage of the total sample size of the studies performed to establish the efficacy of the current AP regimen. Additional research is required - especially from studies evaluating impact on malaria parasitaemia and clinical illness and conducted among travellers in high malaria risk settings - before an abbreviated regimen can be recommended in current practice.

PROSPERO REGISTRATION NUMBER

CRD42017055244.

Characterization of a Plasmodium falciparum Orthologue of the Yeast Ubiquinone-Binding Protein, Coq10p

Coenzyme Q (CoQ, ubiquinone) is a central electron carrier in mitochondrial respiration. CoQ is synthesized through multiple steps involving a number of different enzymes. The prevailing view that the CoQ used in respiration exists as a free pool that diffuses throughout the mitochondrial inner membrane bilayer has recently been challenged. In the yeast Saccharomyces cerevisiae, deletion of the gene encoding Coq10p results in respiration deficiency without inhibiting the synthesis of CoQ, suggesting that the Coq10 protein is critical for the delivery of CoQ to the site(s) of respiration. The precise mechanism by which this is achieved remains unknown at present. We have identified a Plasmodium orthologue of Coq10 (PfCoq10), which is predominantly expressed in trophozoite-stage parasites, and localizes to the parasite mitochondrion. Expression of PfCoq10 in the S. cerevisiae coq10 deletion strain restored the capability of the yeast to grow on respiratory substrates, suggesting a remarkable functional conservation of this protein over a vast evolutionary distance, and despite a relatively low level of amino acid sequence identity. As the antimalarial drug atovaquone acts as a competitive inhibitor of CoQ, we assessed whether over-expression of PfCoq10 altered the atovaquone sensitivity in parasites and in yeast mitochondria, but found no alteration of its activity.

Failure of atovaquone-proguanil malaria chemoprophylaxis in a traveler to Ghana

Clinical failure of Malarone™ chemoprophylaxis is extremely rare. We report a case of Plasmodium falciparum malaria in a returned traveler to Ghana who fully adhered to atovaquone-proguanil (Malarone™) chemoprophylaxis daily dosing, yet took the pills on an empty stomach. Screening of the P. falciparum isolate revealed triple codon mutation of Dhfr at positions 51, 59, and 108. Plasma drug levels of both atovaquone and proguanil revealed sub-therapeutic concentrations.

Babesiosis in an Egyptian boy aquired from pet dog, and a general review

Human babesiosis has been documented in many countries. It is a zoonotic protozoan disease of medical, veterinary and economic importance. In this study, a twelve years old boy was referred to the hospital with intermittent fever of unknown origin. On clinical, parasitological and serological bases the case proved to be babesiosis. The boy acquired the infection from his pet dog which was heavily infested with Rhipicephalus sanguineus and suffered a mild feature of animal babesiosis. The patient was successfully treated with Atovaquone plus Azithromycin without relapse for one month follow up. The pet dog was sent to Governmental Veterinary Hospital at Abbassia for treatment from babesiosis and tick infestation.

Artemether + lumefantrine: new drug. An alternative to atovaquone + proguanil

(1) Treatment of uncomplicated malaria acquired in areas of chloroquine resistance is based on oral drugs chosen according to local resistance patterns. The atovaquone + proguanil combination is often the first choice for travelers because of its tolerability and convenience. (2) For the treatment of uncomplicated malaria, artemisinin derivatives, extracted from a Chinese plant, have a short-lived action and should not therefore be used as monotherapy. (3) Only one combination of this type, artemether plus lumefantrine (an antimalarial related to halofantrine), is marketed in France for the treatment of uncomplicated malaria. (4) In African trials, the efficacy of the artemether + lumefantrine combination, taken in 6 doses over 3 days, was fairly consistent and similar (or even superior) to that of the amodiaquine + sulfadoxine + pyrimethamine combination in three trials. It was more effective than the quinine + doxycycline combination in a region of Brazil where strains with diminished sensitivity to quinine circulate. (5) Artemether has the adverse effects of all artemisinin derivatives, especially gastrointestinal and neurological disorders. Lumefantrine, a drug related to halofantrine, prolongs the QT interval (albeit less than halofantrine), and this sometimes warrants ECG monitoring and blood potassium assays, especially in patients who have hepatic or renal failure or who are taking other drugs that affect the QT interval. (6) The absorption of lumefantrine is dependent on the presence of food in the stomach, which can be difficult as loss of appetite and nausea are frequent during malaria attacks. Intake of about 1.5 g of fat seems sufficient for satisfactory absorption. The artemether + lumefantrine combination is effective in case of resistance to other antimalarials. It is an alternative to the atovaquone + proguanil combination for travelers.

Efficacy of atovaquone-proguanil for treatment of acute multidrug-resistant Plasmodium falciparum malaria in Thailand

A combination of atovaquone-proguanil (Malarone); GlaxoSmithKline, Research Triangle Park, NC) was previously shown to be highly effective in the treatment of uncomplicated Plasmodium falciparum malaria. However, there are only limited recent efficacy data, particularly from regions of multidrug resistance. In this study, we examined the efficacy of atovaquone-proguanil for the treatment of uncomplicated P. falciparum malaria on the Thailand-Myanmar border. Patients were given directly observed atovaquone-proguanil (1,000 mg/400 mg) once a day for three days and followed-up for four weeks in a non-transmission area. Of 140 eligible patients enrolled in this open-label study, 97.8% (95% confidence interval = 95.4-100%) responded to therapy and remained clear of parasitemia at follow-up. Mean parasite clearance time was 41.9 hours and mean fever clearance time was 37.1 hours. On the basis of genotyping, three cases of treatment failure were identified (1 RIII and 2 RI). These data indicate that atovaquone-proguanil remains highly efficacious for the treatment of multidrug-resistant P. falciparum malaria in Thailand.

Motor neuron disease recovery associated with IV ceftriaxone and anti-Babesia therapy

This report summarizes what we believe to be the first verifiable case of a significant and progressive motor neuron disease (MND) consistent with amyotrophic lateral sclerosis that resolved during treatment with i.v. ceftriaxone plus oral atovaquone and mefloquine. The rationale for use of these antibiotics was (i) positive testing for Borrelia burgdorferi and (ii) red blood cell ring forms consistent with Babesia species infection. The patient has continued to be free of MND signs and symptoms for 15 months, although some symptoms consistent with disseminated Borreliosis remain.

Outpatient treatment of malaria in recently arrived African migrants

OBJECTIVE

To describe the clinical features and management of African migrants recently arrived in Western Australia and subsequently diagnosed with malaria.

DESIGN, PARTICIPANTS AND SETTING

Retrospective case record analysis of African migrants aged > or = 16 years with malaria referred to Royal Perth Hospital (RPH) from the WA Migrant Health Unit (MHU) between 1 March 2003 and 30 September 2005.

MAIN OUTCOME MEASURES

Demographic variables; clinical and laboratory variables; Plasmodium species; antimalarial medications used and their efficacy.

RESULTS

57 (3.5%) of 1609 adult African migrants screened at the MHU were diagnosed with malaria and referred for treatment. 52 were infected with P. falciparum, two with P. ovale, one with P. malariae, and one with both P. falciparum and P. malariae; the malaria parasite could not be identified in one individual. No patients had severe malaria by World Health Organization criteria. Most patients (53/57) were treated as outpatients with oral antimalarial therapy; four patients without severe malaria were admitted to hospital for treatment and observation. Atovaquone-proguanil was the antimalarial medication most commonly used (in 52/57), and treatment was well tolerated in most patients. Post-treatment follow-up was possible in 50 patients; all 27 of those who were followed for 4 weeks or longer were cured. Cure could not be concluded in patients with shorter follow-up periods. All follow-up blood films were negative for malarial parasites.

CONCLUSIONS

Outpatient treatment of malaria in recently arrived adult African migrants appeared to be safe and efficacious in our cohort.

Pharmacokinetics of dihydroartemisinin following oral artesunate treatment of pregnant women with acute uncomplicated falciparum malaria

OBJECTIVE

To determine the pharmacokinetic properties of dihydroartemisinin (DHA) following oral artesunate treatment in women with recrudescent multi-drug resistant falciparum malaria, in the second and third trimesters of pregnancy.

METHODS

Serial plasma concentrations of artesunate and DHA were measured in 24 women after the final dose of a 3 day treatment with artesunate (4 mg kg(-1) day(-1)) and atovaquone (20 mg kg(-1) day(-1)) plus proguanil (8 mg kg(-1) day(-1)), daily. Conventional non-compartmental modelling and a population one-compartment pharmacokinetic model were applied to the data.

RESULTS

Artesunate was very rapidly eliminated. For DHA the median [90% range] estimate of oral clearance (CI/F) was 4.0 [0.8-20.7] l hour(-1) kg(-1), total apparent volume of distribution (Vd/f) was 3.4 [0.9-60.7] l/kg, and terminal elimination half-life was 1.0 [0.6-2.4] h.

CONCLUSION

The kinetics of DHA are modified by pregnancy. The plasma levels of the active antimalarial metabolite DHA are lower than reported previously in non-pregnant adults. Dose-optimisation studies in pregnant women are needed.