Efficacy and safety of atovaquone/proguanil as suppressive prophylaxis for Plasmodium falciparum malaria

Currently recommended prophylactic regimens for Plasmodium falciparum malaria are associated with a high incidence of adverse events and/or suboptimal efficacy. In a double-blind, placebo-controlled, randomized clinical trial in western Kenya, adult volunteers received a treatment course of atovaquone/proguanil hydrochloride (250 mg/100 mg per tablet) to eliminate preexisting infection. Immediately thereafter, subjects were randomized to one of the three prophylactic regimens to receive one atovaquone/proguanil tablet daily (n = 68), two atovaquone/proguanil tablets daily (n = 65), or placebo (n = 65) for 10 weeks. The study endpoint for any subject was the development of parasitemia, evident on blood smear, during prophylaxis. Of the evaluable subjects, all in the low-dose (54 of 54) and high-dose (54 of 54) atovaquone/proguanil groups remained malaria-free during the 10-week prophylaxis period, in contrast to only 48% (26 of 54) in the placebo group (P < .001). Both atovaquone/proguanil prophylactic regimens were as well tolerated as placebo. Thus, atovaquone/proguanil appears to be highly efficacious and safe as prophylaxis for P. falciparum malaria.     

Atovaquone and proguanil for the treatment of malaria in Brazil

The purpose of this study was to compare an experimental regimen of atovaquone plus proguanil with the standard regimen of quinine plus tetracycline for the treatment of uncomplicated falciparum malaria. The study was designed as an open, randomized study of men presenting with symptoms of uncomplicated malaria and thick-smear slide confirmation of parasitemia (1000-100,000 ring forms/microL). Subjects were hospitalized for 28 days to insure medication compliance and to rule out the possibility of reinfections. With 77 patients in each group, the cure rates were 98.7% and 100% for atovaquone plus proguanil and quinine plus tetracycline, respectively. The parasite clearance times (mean, 56 h) and fever clearance times (mean, 19 h) were significantly shorter in the atovaquone plus proguanil group, and there were significantly fewer side effects in the atovaquone plus proguanil group. Atovaquone plus proguanil is an efficacious, easily administered, safe regimen for the treatment of uncomplicated, multidrug-resistant falciparum malaria in Brazil.     

Research on new antimalarial drugs and the use of drugs in combination at the Bangkok Hospital for Tropical Diseases

With the emergence of multidrug resistant falciparum malaria in Thailand, various approaches have been taken. Research on new antimalarial drugs and the use of existing available drugs with modification are urgently needed. New drugs and drugs in combination such as pyronaridine, WR 238605, arteether, dihydroartemisinin, benflumetol atovaquone/proguanil are being evaluated. Drug combinations for the treatment of patients suffering from uncomplicated falciparum malaria include quinine-tetracycline for 7 days, or sequential treatment of artesunate (600 mg given over 5 days) followed by mefloquine (1,250 mg divided into 2 doses 6 hours apart) are recommended. The sequential treatment is highly recommended for those who failed other treatment regimens. Other combinations such as a short course sequential treatment of artesunate (300 mg given over 2.5 days) followed by a single dose of 750 mg mefloquine, or a combination of mefloquine 1,250 mg together with tetracycline 1 g per day or doxycycline 200 mg per day for 7 days are alternative treatment regimens with acceptable cure rates. The simultaneous administration of artesunate and mefloquine, in various doses and duration of treatment, is currently being investigated. Until proven otherwise, the drug combinations are still recommended for all adult patients suffering from acute uncomplicated falciparum malaria contracted in multidrug resistant areas. In severe malaria and malaria in children, the drug combinations need further investigation.     

Pharmacokinetics of proguanil in malaria patients treated with proguanil plus atovaquone

Clinical studies have shown atovaquone (ATQ), a new blood schizontocidal drug, in combination with proguanil (PROG) to be very effective in the treatment of acute multidrug-resistant falciparum malaria. The multiple dose pharmacokinetics of PROG were determined in Thai patients with acute falciparum malaria given PROG alone (200 mg PROG twice a day for 3 days, n = 4) and concurrently PROG and ATQ (200 mg PROG and 500 mg ATQ twice a day for 3 days, n = 12). There were no statistical differences (p > 0.05) in the area under the plasma drug concentration-time curve (AUC), apparent oral clearance (CL/F) and elimination half-life (t1/2) of PROG between patients given PROG alone and PROG/ ATQ. The median (range) kinetic values of PROG in patients given PROG alone and PROG/ATQ were respectively: CL/F = 1.25 l/h/kg (0.99-1.45) and 0.95 (0.73-1.32) l/h/kg, and t1/2 = 14.2 hours (9.3-16.8) and 13.6 hours (9.1-17.6). The CL/F and t1/2 of PROG in the Thai patients treated with the 2 treatment regimens were also comparable to values reported in healthy Thai volunteers given a standard prophylactic dose (200 mg PROG). The results of this preliminary study suggest that ATQ is unlikely to affect the pharmacokinetics of PROG to a clinically important extent at an ATQ dosage of 500 mg twice a day for 3 days in malaria infected patients.     

An evaluation of surveillance of malaria at primary health care level in Kenya

As less than twenty five per cent of persons suffering from malaria seek formal treatment in most of sub-Saharan Africa, Facility-based morbidity statistics are inadequate for monitoring malaria control programmes. This explorative study assessed whether a health centre equipped with a microscope and trained personnel could monitor malaria transmission within its catchment area. The study was conducted at Chemase Health Centre in Nandi District in Kenya, an area holoendemic for malaria with Anopheles gambiae as the main vector and Plasmodium falciparum as the commonest cause of malaria. From first August to 31 October 1991, first seven children under five years of age on each working day accompanied by their mothers to the maternal and child health clinic were studied. A general examination was performed by a Registered Clinical Officer (Medical Assistant) and thin and thick blood smears made, stained with Giemsa stain and examined for malaria parasites by a Medical Laboratory Technologist. Mothers were interviewed by enrolled community nurses on antimalarial measures they were using in their homes. Four hundred and fifty five children mostly under five years of age, consisting of 48.1% males and 51.9% females, were studied. Malaria parasites were present in 209 (45.9%) blood smears of the children. The percentage of blood smears positive for malaria parasites was high in children below 36 months of age. There was a tendency for low percentage of blood smears positive for malaria in children whose mothers reported using mosquito nets or insecticide sprays. The study did not interrupt the routine of the health centre. Periodic monitoring of new malaria illnesses. and percentage of blood smears positive for malaria parasites in children aged 0 to 35 months should be introduced into health centre practice in Kenya. This catchment area approach could be used to monitor malaria control programmes as well as predicting malaria epidemics.     

Evaluation of atovaquone in the treatment of patients with uncomplicated Plasmodium falciparum malaria

The activity of atovaquone in patients with oligosymptomatic Plasmodium falciparum malaria was assessed in an open, non-comparative clinical study. The patients showed a good clinical response, but there was a high rate of recrudescence. The activity of atovaquone in combination with another antimalarial agent should be investigated.     

Comparison of adverse events associated with use of mefloquine and combination of chloroquine and proguanil as antimalarial prophylaxis: postal and telephone survey of travellers

OBJECTIVE: To compare the frequency of adverse events, particularly neuropsychiatric effects, from mefloquine and from chloroquine plus proguanil as used for malaria chemoprophylaxis. DESIGN: Retrospective questionnaire to travellers taking either regimen between November 1993 and February 1995; telephone interview with those reporting pronounced side effects. SETTING: Travellers from Britain who consulted an advisory helpline. SUBJECTS: 1214 adults taking mefloquine and 1181 taking chloroquine plus proguanil. MAIN OUTCOME MEASURES: Reported presence of and degree of disability from 12 neuropsychiatric and other symptoms, as assessed by the subjects and by referees and on the basis of behaviour change. RESULTS: There were equal rates of any side effects (40%) and of stopping or changing medication. Overall, neuropsychiatric adverse events were significantly more common in travellers taking mefloquine. In all, 333 neuropsychiatric adverse events were reported by 1214 travellers taking mefloquine, compared with 189 such events in 1181 travellers taking proguanil plus chloroquine (P < 0.001). In all, 0.7% of travellers taking mefloquine had disabling neuropsychiatric adverse effects, compared with 0.09% of those taking proguanil plus chloroquine (P = 0.021). Two travellers taking mefloquine (1 in 607) were admitted to hospital as a result of the adverse event, compared with 1 in 1181 travellers taking proguanil plus chloroquine. CONCLUSION: There is a significant excess of adverse neuropsychiatric events of intermediate degrees of severity associated with the use of mefloquine compared with proguanil plus chloroquine. This finding may also explain the discrepant findings between earlier studies and clinical experience.     

The analysis of methamphetamine hydrochloride by thermal desorption ion mobility spectrometry and SIMPLISMA

The treatment of malaria tropica is becoming difficult because of the increasing drug resistance rates of Plasmodium falciparum against several of the currently available antimalarias. A fixed combination of rifampicin, co-trimoxazole and isoniazid (CotrifazidTM, CF) was found to be highly effective for the treatment of malaria tropica. The aim of the present study in Kenya was to scrutinize this finding in a 14-day trial. Patients with malaria tropica were given in an open, double-arm randomized study CF for 5 days, or chloroquine or pyrimethamine/sulphadoxine as the control. Because of an apparently better activity and tolerance of CF, the randomization had to be stopped after the enrollment of 50 patients. A total of 61 patients in both groups (35 of them between 2 months and 6 years of age) were available for final analysis. All 41 patients treated with CF, originally positive in their blood smears, turned negative; in 2 cases blood smear positivity reappeared on day 14. There were 7 failures in the control group, 4 of them a primary one. Four of those failures were turned negative with CF, 2 failed with CF also, and 1 disappeared. The tolerance of CF was excellent even in infants. In our experience, CF is very well suited for the treatment of malaria tropica, also in cases of apparent drug resistance of P. falciparum against other antimalarials, and even in severe cases of the disease.     

Fluticasone propionate aqueous nasal spray is safe and effective for children with seasonal allergic rhinitis

INTRODUCTION: Fluticasone propionate aqueous nasal spray, a new topical corticosteroid preparation, is effective when given as 200 micrograms once daily in patients (> 12 years of age) with seasonal allergic rhinitis. STUDY OBJECTIVE: To evaluate the efficacy and safety of fluticasone proprionate aqueous nasal spray in children aged 4 to 11 years with seasonal allergic rhinitis. STUDY DESIGN: Multicenter, randomized, double-blind, placebo-controlled, parallel-group. PATIENTS: Two hundred fifty children aged 4 to 11 years with moderate-to-severe nasal symptoms, a positive skin test reaction to a late-summer or autumn allergen, a history of seasonal allergic rhinitis, and documentation of an unsatisfactory response to conventional treatment. INTERVENTIONS: Children were randomly assigned to receive fluticasone propionate, either 100 micrograms or 200 micrograms, or placebo, given by intranasal spray once daily in the morning for 14 days. MEASUREMENTS AND RESULTS: Severity of nasal symptoms (obstruction, rhinorrhea, itching, and sneezing) was recorded on visual analog scales by investigators at weekly visits and by patients (or adult guardian) daily in the evening. According to investigator and patient ratings, both fluticasone propionate 100 micrograms/d and 200 micrograms/d lowered total nasal symptom scores when compared with placebo. Both dosages of fluticasone propionate were more effective than placebo on the basis of investigator-rated overall clinical evaluation of efficacy at the end of treatment, with significant improvement (as opposed to moderate or mild improvement, no change or worsening) noted in 21% to 29% of the active-treatment groups vs 9% in the placebo group. There were no significant differences between the two fluticasone propionate dosages in any efficacy measurement. Morning plasma cortisol concentrations and frequency of drug-related adverse events were similar in the fluticasone propionate and placebo groups. CONCLUSION: In children as young as 4 years, 100 micrograms of fluticasone propionate aqueous nasal spray given once daily is as effective as 200 micrograms given once daily, the usual adult dose for the treatment of seasonal allergic rhinitis. Both fluticasone propionate dosages were well tolerated and neither dosage appears to interfere with the hypothalamic-pituitary-adrenal axis in children.     

Characterization of Plasmodium falciparum isolated from the Amazon region of Brazil: evidence for quinine resistance

The prevalence and severity of drug-resistant malaria is emerging rapidly in the Amazon basin of Brazil. In support of clinical trials using the new antimalarial drug combination of atovaquone and proguanil, we performed in vitro drug sensitivities, molecular characterization of parasite populations using the circumsporozoite protein, merozoite surface antigen-1 (MSA-1), and MSA-2 markers, and an analysis of the Plasmodium falciparum multidrug resistance (pfmdr1) gene sequence and copy number in 26 isolates of P. falciparum obtained in a gold-mining endemic area in Peixoto de Azevedo, Mato Grosso State. All 26 isolates were found to be resistant to chloroquine (50% inhibitory concentration [IC50] = 100-620 nM) and sensitive to mefloquine (IC50 < 23 nM) and halofantrine (IC50 < 6 nM). The isolates also show reduced susceptibility to quinine (IC50 = 48-280 nM). Sequence analysis of the pfmdr1 gene revealed Asn, Phe, Cys, Asp, and Tyr in positions 86, 184, 1034, 1042, and 1246, respectively. These point mutations were similar to that previously described in other Brazilian isolates. Southern blot analysis revealed no amplification of the pfmdr1 gene. These results suggest that three different mechanisms for drug resistance exist for chloroquine, mefloquine, and quinine.     

Perianal disease, growth failure, and quality of life

The micro-wave oven permits a rapid drying of thick blood smears classically used for parasitological malaria diagnosis. In order to evaluate this type of drying on the microscopic reading, a study was carried out in an hyperendemic area of malaria with 382 asymptomatic volunteers of all ages. Two thick smears were made for each volunteer, one immediately dried with a micro-wave oven for one minute, the second dried in the open air without any intervention. A single microscopist examined all the thick smears. The observation of Plasmodium falciparum trophozoites differed significantly between the two methods, the prevalence was 50% by normal drying versus 41% by the micro-wave oven. The geometric mean of the trophozoite number for positive thick smears was significantly lower with the micro-wave oven. When the parasitological density with normal drying was lower than 200 trophozoites/microliter of blood, 54% of results were wrongly negative with the micro-wave oven. On the other hand, the observation of P. falciparum gametocytes was significantly facilitated after drying with the micro-wave oven; the prevalence was 8% with normal drying versus 12% by micro-wave oven. In conclusion, the use of the micro-wave oven for the drying of thick smears is not recommended for malaria diagnosis although it improves the observation and counting of P. falciparum gametocytes.     

Malaria chemosuppression in pregnancy. V. Placenta malarial changes among three different prophylaxis groups

The effect of malaria chemoprophylaxis during pregnancy on placenta malarial changes (PMCs) was investigated in 170 tissue sections. Women of 63 sections received daily proguanil (PROG), 61 once weekly chloroquine (CQ) and 46 the two drug combination (CQ+PROG). All were residents of a malaria hyperendemic area in Muheza District, Tanzania. Supervised prophylaxis started early in pregnancy till delivery. Parasitaemias and clinical episodes were detected early and radically treated. Overall, PMCs were mostly infrequent and light viz: fibrinous deposits (98%), fibrinoid necrosis (60%), leucocytic infiltrations (59%), macrophage containing pigment (16%), and malaria parasites (8%). The type, prevalence, and severity of the PMCs in the three prophylaxis groups were comparable. This was despite the fact that PROG and CQ+PROG were prophylactically more efficacious than CQ and despite the expectation that the prevalence and severity of the PMCs would be high in the CQ group. Prompt diagnosis and effective treatment of parasitaemias in this group contributed to the low prevalence and less severity. It is concluded that effective malaria chemoprophylaxis or prompt diagnosis and effective treatment of malaria parasitaemias have significant impact on the prevalence of PMCs. Due to various operational constraints in most developing countries, chemoprophylaxis remains the only feasible broad option for malaria control in pregnancy.     

Transformation with human dihydrofolate reductase renders malaria parasites insensitive to WR99210 but does not affect the intrinsic activity of proguanil

Increasing resistance of Plasmodium falciparum malaria parasites to chloroquine and the dihydrofolate reductase (DHFR) inhibitors pyrimethamine and cycloguanil have sparked renewed interest in the antimalarial drugs WR99210 and proguanil, the cycloguanil precursor. To investigate suggestions that WR99210 and proguanil act against a target other than the reductase moiety of the P. falciparum bifunctional DHFR-thymidylate synthase enzyme, we have transformed P. falciparum with a variant form of human DHFR selectable by methotrexate. Human DHFR was found to fully negate the antiparasitic effect of WR99210, thus demonstrating that the only significant action of WR99210 is against parasite DHFR. Although the human enzyme also resulted in greater resistance to cycloguanil, no decrease was found in the level of susceptibility of transformed parasites to proguanil, thus providing evidence of intrinsic activity of this parent compound against a target other than DHFR. The transformation system described here has the advantage that P. falciparum drug-resistant lines are uniformly sensitive to methotrexate and will complement transformation with existing pyrimethamine-resistance markers in functional studies of P. falciparum genes. This system also provides an approach for screening and identifying novel DHFR inhibitors that will be important in combined chemotherapeutic formulations against malaria.     

Hereditary angioedema: case report and review of management

For treatment of malaria, the World Health Organization recommends 10 mg of quinine per kg body-weight 3 times a day for at least 7 d. In Guinea-Bissau, as in several other African countries, a 3 d treatment regimen (10 mg/kg twice daily) is currently used. We therefore compared the 3 d treatment period with periods of 5 and 7 d. A total of 145 children with clinical malaria due to monoinfection with Plasmodium falciparum, with > or = 20 parasites per 200 leucocytes, were treated with intramuscular Quinimax 10 mg per kg body-weight twice daily for 3, 5 or 7 d. The children were then examined once weekly for 4 weeks. Following the 3 d treatment regimen, 34 of 43 children (79%) had parasitaemia on day 28 or before; following the 5 d treatment regimen, 36 of 40 children (90%) did so; and following the 7 d treatment regimen, 7 of 62 children (11%) were parasitaemic at that time. This study thus suggests that the currently recommended 3 d Quinimax treatment regimen in Guinea-Bissau for moderate and severe malaria is not effective.     

Cycloguanil and its parent compound proguanil demonstrate distinct activities against Plasmodium falciparum malaria parasites transformed with human dihydrofolate reductase

The lack of suitable antimalarial agents to replace chloroquine and pyrimethamine/sulfadoxine threatens efforts to control the spread of drug-resistant strains of the malaria parasite Plasmodium falciparum. Here we describe a transformation system, involving WR99210 selection of parasites transformed with either wild-type or methotrexate-resistant human dihydrofolate reductase (DHFR), that has application for the screening of P. falciparum-specific DHFR inhibitors that are active against drug-resistant parasites. Using this system, we have found that the prophylactic drug cycloguanil has a mode of pharmacological action distinct from the activity of its parent compound proguanil. Complementation assays demonstrate that cycloguanil acts specifically on P. falciparum DHFR and has no other significant target. The target of proguanil itself is separate from DHFR. We propose a strategy of combination chemotherapy incorporating the use of multiple parasite-specific inhibitors that act at the same molecular target and thereby maintain, in combination, their effectiveness against alternative forms of resistance that arise from different sets of point mutations in the target. This approach could be combined with traditional forms of combination chemotherapy in which two or more compounds are used against separate targets.     

ARDS in plasmodium vivax malaria

Acute renal failure, disseminated intravascular coagulation, ARDS, hypoglycaemia, coma or epileptic seizures are manifestations of severe Plasmodium falciparum malaria. On the other hand, vivax malaria or benign tertian malaria is usually free from complications. In the present report we describe a case of acute tertian malaria with a severe and complicated course. In this situation bacterial coinfection should always be suspected and treated empirically with broad-spectrum antibiotics, until the results of cultures are available. Mixed plasmodial infection (P. vivax and P. falciparum) must be excluded by repeated and meticulous examination of blood smears. Newer techniques such as PCR processing or ParaSight F Test are mentioned.     

Correlation of structure and function in the chicken lower intestine (coprodeum): a review

The rapid manual ParaSight-F test of Plasmodium falciparum malaria, an antigen capture test for detecting trophozoite-derived histidine rich protein-2 (PF HRP-2), is simple to perform and provides a definite diagnosis within 10 minutes. During an operational trial at health centers and mobile malaria units where microscopical diagnosis is not available and using defined symptom screening criteria, 3,361 subjects were tested yielding 618 positives (18.4%) for PF-HRP-2 by ParaSight-F. Microscopic examination of the same subjects by thick blood film examined 7 days later at a malaria clinic showed 578 falciparum, and 349 vivax and mixed infection (F+V) 41. The technology proved highly effective in detecting falciparum malaria at the peripheral levels where access to malaria laboratory services are difficult, thus allowing immediate administration of a complete course of treatment in the absence of a microscopic examination.     

Current concepts and controversies in IgA nephropathy

A randomized, open trial involving 260 Tanzanian children, aged 1-5 years, with acute Plasmodium falciparum malaria was conducted to evaluate the efficacy of the combination antimalarial CGP 56697 (artemether and benflumetol), and to compare it with chloroquine, the standard drug used for malaria treatment in the Kilombero area. Children who had received rescue medication within the first 48 h or had a negative slide at the same time were excluded. Seven-day parasitological cure rates were 94% (95% CI 88-97.5) for CGP 56697 and 35.4% (95% CI 25.9-45.8) for chloroquine. Using the same definition, the 14-day parasitological cure rates were 86.4% (95% CI 78.5-92.2) for CGP 56697 and 10.3% (95% CI 5.1-18.1) for chloroquine. Gametocytes were more effectively suppressed by CGP 56697 than by chloroquine. There were no major adverse events with either drug. CGP 56697 is highly efficacious against P. falciparum in this area of Tanzania. The study contributes to the discussion on treatment strategies, particularly whether chloroquine may still fulfil its role as first-line drug in an area of high malaria transmission and very high levels of chloroquine resistance.     

The journal 150 & 100 years ago. May 1848 and 1898

AIM: To study the therapeutic efficacy of low dose intravenous artesunate followed by oral mefloquine in severe falciparum malaria in Singapore. METHODOLOGY: Retrospective review of 4 cases of severe falciparum malaria admitted for treatment in a private hospital in the first six months of this year. Patients were considered cured when no malaria parasites were detected in the blood film on discharge and remained afebrile at 28 days. RESULTS: This drug regimen was well tolerated, rapidly reduced parasitaemia and achieved 100% cure in all four patients. CONCLUSION: Low dose intravenous artesunate followed by mefloquine was found to be well tolerated and rapidly effective in treating severe falciparum malaria contracted in Indonesia and India. There was no relapse of clinical disease in all four cases after 28 days.     

Effects of malaria infection in human immunodeficiency virus type 1-infected Ugandan children

BACKGROUND: Malaria causes severe morbidity and mortality in many areas of Africa where HIV-1 infection is also prevalent. Immunosuppression is associated with both diseases but most reports do not find significant interactions between them. METHODS: A collaborative study of HIV-1 infection in Ugandan women and their infants was established between the Ministry of Health, Makerere University, Kampala, and Case Western Reserve University in 1988. Four hundred fifty-eight infants, including 77 HIV-1-infected, 232 seroreverter and 125 control children born to HIV-1-negative mothers and 24 of indeterminate status were followed closely from birth for 4 years. Data on these infants were reviewed with respect to episodes of general illness and infections, suspected and confirmed episodes of malaria, onset and frequency of malaria, use of chloroquine and occurrence of selected illnesses after episodes of febrile illnesses. Thick and thin blood smears for malaria were obtained from children with fever. RESULTS: There was no association between occurrence of febrile illnesses and childrens' HIV-1 category. The relative rates of occurrence were 1.0 (95% confidence interval (CI), 0.8 to 1.2) and 1.1 (95% CI 0.9 to 1.4) for the HIV seroreverter and control children compared with the HIV-infected children. Although there was no association (P = 0.83) between HIV-1 status and a smear being taken during a febrile episode, there was an increase in smears positive for malaria parasitemia among seroreverter (risk ratio, 1.5; 95% CI 1.1 to 1.9) and control infants (risk ratio, 1.6; 95% CI 1.2 to 2.2) compared with HIV-1-infected infants. The level of parasitemia was similar in each group. A greater proportion of malaria episodes among the HIV-infected group than among the control groups resulted in hospitalizations (P = 0.001) and blood transfusions (P = 0.02). There was a positive association between time to clinical AIDS and absence of malaria (adjusted for follow-up age) in infected children (P = 0.02). Use of chloroquine was similarly high in each HIV-1 category (80%). CONCLUSIONS: In this group of HIV-infected children there was no significant increase in malarial episodes as compared with their HIV-negative controls. The results suggest a possibility that malaria may offer some protection against HIV-1 progression or that chloroquine used to treat malaria may have a direct effect against the HIV-1 virus.