Molecular epidemiology of malaria in cameroon. IX. Characteristics of recrudescent and persistent Plasmodium falciparum infections after chloroquine or amodiaquine treatment in children

In the absence of a firmly established gene responsible for chloroquine and amodiaquine resistance in Plasmodium falciparum, surveillance of resistance to these first-line drugs in Cameroon needs to be performed by in vivo or in vitro tests for drug resistance. These 2 methodological approaches to define drug resistance were shown to be complementary and concordant in a majority of cases at our study sites, but discordant results may be observed in a few cases, probably as a result of acquired immunity and low plasma drug levels. To further examine the nature of recrudescent and persistent parasitemia after treatment with chloroquine or amodiaquine, the clinical response of children aged < 5 years, presumably with insufficient immune response, was assessed, and the in vitro response of the corresponding isolates was determined if treatment or parasitological failure occurred. Genotyping of pretreatment and posttreatment isolates was performed by polymerase chain reaction to distinguish between recrudescence and reinfection. Plasma drug levels were measured at the time of therapeutic failure by high-performance liquid chromatography. All cases of therapeutic or parasitological failure observed on or before Day 14 were due to the persistence or recrudescence of the original parasite populations present before treatment, with or without selection and appearance of new populations. Most parasites were characterized by elevated 50% inhibitory concentrations for chloroquine and amodiaquine at the time of clinical or parasitological failure. In some children, recrudescence was explained by the absence of drug in the plasma. The simultaneous analysis of clinical and in vitro responses, plasma drug level measurement, and genotyping may yield results that may explain the reasons for therapeutic failure, help establish the threshold level for in vitro resistance, and provide a set of more accurate tools to describe the epidemiology of drug-resistant P. falciparum while awaiting for the identification of the chloroquine and amodiaquine resistance gene or genes.     

Multi-drug resistant Plasmodium falciparum malaria in Assam, India: timing of recurrence and anti-malarial drug concentrations in whole blood

The susceptibility of 23 cases of Plasmodium falciparum malaria from the Sonapur primary health center in the Kamrup district of Assam, India to different antimalarials was investigated using the 28-day World Health Organization in vivo test. Whole blood concentrations of chloroquine, sulfadoxine, and quinine were determined at different intervals and at the time of parasites recrudescence after completion of treatment with the respective drugs to confirm the status of drug sensitivity. A case of multi-drug resistant P. falciparum malaria was found where recrudescence occurred, despite standard oral treatment with chloroquine, sulfadoxine/pyrimethamine, and quinine sequentially. Whole blood concentrations of chloroquine, sulfadoxine, and quinine at the time of recrudescence were 0.35 microg/ml (day 7), 18 microg/ml (day 14), and 0.009 microg/ml (day 14), respectively. Therefore, monitoring of drug-resistant P. falciparum malaria and its proper treatment should be intensified to check the spread of multi-drug resistant strains in other parts of the country.     

Molecular epidemiology of malaria in Cameroon. XIV. Plasmodium falciparum chloroquine resistance transporter (PFCRT) gene sequences of isolates before and after chloroquine treatment

Laboratory studies have strongly suggested that the gene coding for Plasmodium falciparum chloroquine resistance transporter (PFCRT) may play a determinant role in chloroquine resistance. A clinical study in Mali also found evidence for selection of the key PFCRT amino acid substitution, Lys76Thr, in patients who fail to respond to chloroquine treatment. To test the hypothesis that in vivo selection of mutant PFCRT alleles occurs after chloroquine treatment, PFCRT and merozoite surface antigen 2 (msa-2) polymorphisms were compared between 61 pretreatment and posttreatment paired samples from children with either clinical or parasitologic failure. There were six wild-type PFCRT alleles, 44 mutant alleles, and 11 mixed alleles among pretreatment isolates. All posttreatment parasites had mutant PFCRT alleles. Recrudescence accounted for 42 of 61 posttreatment infections, while 19 posttreatment infections were due to new infection (including all isolates with Lys-76 before treatment and Thr-76 after treatment). Seven pretreatment isolates with mixed PFCRT alleles had only Thr-76 on recrudescence, providing a direct evidence for in vivo selection for mutant PFCRT. Although the presence of mutant PFCRT alleles in pretreatment isolates is not predictive of chloroquine treatment failure, our data support the hypothesis that in vivo selection for recrudescent parasites carrying mutant PFCRT alleles occurs. These results may have important implications for the future surveillance of chloroquine resistance by the use of molecular markers.     

Molecular analysis of Plasmodium falciparum recrudescent malaria infections in children treated with chloroquine in Nigeria

Parasite genotyping by a polymerase chain reaction was used to distinguish recrudescent from newly acquired Plasmodium falciparum infections in 50 of 160 Nigerian children taking part in a chloroquine efficacy study in Ibadan, Nigeria. A finger prick blood sample was taken from each child before and after treatment to identify recrudescent parasites. By investigating allelic variation in three polymorphic antigen loci, merozoite surface protein-1 (MSP-1), MSP-2, and glutamate-rich protein (GLURP), we determined parasite diversity in the population and in the infected host. DNA from pretreatment and post-treatment samples from 47 of the 50 patients who failed therapy was successfully amplified by the PCR. The MSP-1, MSP-2, and GLURP genotypes in all samples showed extensive diversity, indicating polyclonal infections. The average number of clones per infection in pre-treatment sample was 2.5 with MSP-1, 4.9 with MSP-2, and 2 with GLURP. The extent of multiplicity decreased significantly (P = 0.016) in posttreatment samples. Multiplicity of infection and initial parasite density were not age dependent. Comparison of the variant alleles in pretreatment and post-treatment samples of each patient indicates that 26 of the 47 children had genuinely recrudescent disease. Conversely, post-treatment samples from five children showed completely new genotypes, indicating either a previously sequestered population of parasites or a newly acquired infection. Overall, this study has shown the diversity and complexity of P. falciparum population in Ibadan, Nigeria. The study has also shown the dynamics of P. falciparum infections in this population before and after chloroquine treatment in an area of high malaria transmission.     

Short report: Molecular evaluation of the efficacy of chloroquine treatment of uncomplicated Plasmodium falciparum malaria in East Timor

The efficacy of chloroquine treatment of uncomplicated Plasmodium falciparum malaria in East Timor was investigated via molecular tools. Genotyping of the polymorphic markers msp1 and msp2 was performed to investigate the number and type of parasite alleles in pre- and posttreatment blood samples collected from 48 patients. Patients were infected with a minimum of 8 msp1 and 14 msp2 allelic types of parasite, and 43% of the patients had more than one allelic type before treatment. The genotyping also revealed that 66.7% of the patients were infected with at least one identical allelic type of parasite before and after treatment and therefore were likely to have experienced recrudescence. All parasites in pre- and posttreatment blood samples carried the K76T mutation in pfcrt, regardless of the clinical response to chloroquine. The sequence polymorphism patterns in pfcrt in the majority of parasites examined were identical to those observed in Bougainville, Papua New Guinea.     

随机扩增的多态性DNA分析在Hp菌株鉴定中的应用

目的:建立一种快速准确鉴定不同Hp菌株的RAPD分析方法,并评价其在区分Hp复发和再感染中的应用价值。方法:用苯酚—氯仿方法提取Hp DNA,以一个10nt的寡核苷酸为引物,建立Hp PCR扩增体系,所得PCR产物以2％琼脂糖凝胶电泳分析(RAPD分析),以50株临床分离的Hp菌株检测该方法的重复性。对4例十二指肠溃疡伴Hp感染者在三联治疗前后及根除后一年内再现的Hp菌株进行RAPD分析,鉴别复发和再感染。结果:(1)同-Hp菌株于不同时间进行的2次RAPD分析,所得的PCR产物完全一致,说明该方法具有良好的可重复性。(2)50株不同的Hp菌株各产生不同的RAPD图谱,可按此图谱的不同将它们区分开来。(3)对4例十二指肠溃疡伴Hp感染者在治疗前及治疗后1年再现的菌株的RAPD分析,发现3例患者的菌株具有相同的RAPD图谱,证实为原菌株的复发,而1例患者的菌株则产生不同的RAPD图谱,推测为新菌株的再感染。4例患者随访1年均为十二指肠溃疡复发。结论:RAPD分析只需单一的随机引物,方法简便、快速、经济、重复性好,可用于区分不同来源的Hp菌株,特别对治疗前后再现的菌株复发和再感染的鉴别更具临床应用价值。     

Distinction of recrudescences from new infections by pcr-rflp analysis in a comparative trial of cgp 56 697 and chloroquine in Tanzanian children.

Summary objective To test the efficacy of a new compound drug (CGP 56 697) against acute, uncomplicated falciparum malaria. method Reappearing parasites were analysed by PCR-RFLP within a randomized controlled trial. 130 patients received chloroquine and 130 patients were treated with CGP 56 697. Samples from 96 patients with parasitological failure were tested by PCR-RFLP for MSP2 of Plasmodium falciparum. Seven days after treatment 32 patients of the chloroquine control group with reappearing parasites were tested by PCR and one infection was unequivocally determined as a new infection. After 7 days, in the CGP 56 697 group, 6 samples were tested in which one new infection was identified. Similar observations were made one and three weeks later in both groups. results Although a high multiplicity of infections on admission was observed, there was no significant correlation between multiplicity and either recrudescence or new infection. Patients in both treatment groups with subsequent recrudescent parasites had higher initial mean parasite densities than patients who cleared. Those of the patients with recrudescent parasites who were treated with CGP 56 697 had higher initial parasite densities than those treated with chloroquine. The rate of re-infection increased with time as expected in holoendemic areas and appeared to be higher in chloroquine patients. Generally, CGP 56 697 showed a superior clearance rate, successfully cleared higher parasite densities and suppressed new infections over a longer period of time. conclusion The PCR analysis confirmed that reinfections beyond day 7 are significant in areas highly endemic for malaria and showed the necessity of excluding these when estimating 14 day clearance rates. Provided new infections are excluded, the 28-day clearance rate can also be used to determine the efficacy of antimalarial drugs in highly endemic areas, and adds to our knowledge of drug resistance and dynamics of infections in people living in such areas.     

Distinguishing recrudescence from reinfection in a longitudinal antimalarial drug efficacy study: comparison of results based on genotyping of msp-1, msp-2, and glurp

Genotyping frequently is used to distinguish recrudescent from new infections in antimalarial drug efficacy trials, but methodology and interpretation of results have not been standardized. We compared the utility of polymorphisms within 3 Plasmodium falciparum genes during a longitudinal trial in Kampala, Uganda. Merozoite surface protein-1 (msp-1) and merozoite surface protein-2 (msp-2) revealed greater diversity than glutamate-rich protein. Genotypes based on msp-1, msp-2, and all 3 genes combined were compared for 394 initial and subsequent isolates. Classification of most episodes as due to recrudescence or reinfection was straightforward. In 24% (msp-1), 16% (msp-2), and 62% (3 genes combined) of samples, subsequent episodes contained identical and new alleles, however. Our analysis suggested that such episodes should be classified as reinfections and not recrudescence. Comparing the 3 studied genes, msp-2 results were most accurate, and analysis of this single gene effectively distinguished recrudescence from reinfection in our study population.     

Molecular epidemiology of malaria in Yaounde, Cameroon. VIII. Multiple Plasmodium falciparum infections in symptomatic patients.

The extent of genetically distinct parasite populations coinfecting individual human hosts (i.e., multiplicity) was studied by polymerase chain reaction amplification of 3 polymorphic genetic markers, circumsporozoite protein and merozoite surface antigens (MSA) 1 and 2, in symptomatic children and adults and analyzed in relation with age and initial parasitemia. Of the total of 177 DNA samples analyzed (of which 115 were paired pre- and posttreatment samples), 101 (57%) were composed of multiclonal infections, with up to 7 distinguishable parasite populations. Among the 3 polymorphic markers, msa-2 yielded the highest proportion of clinical isolates with multiclonal populations. Patients with multiclonal infections before treatment had, on average, 2.9 genetically distinct parasite populations. The extent of multiplicity decreased significantly (P < 0.05) in recrudescent parasites, but not with reinfections, as compared with the pretreatment samples. Neither age (5-60 years) nor initial parasitemia was correlated with multiplicity. Further studies in different epidemiological settings are required to understand the role of multiclonal Plasmodium falciparum infections in influencing malaria transmission.     

Polymorphisms of molecular markers of antimalarial drug resistance and relationship with artesunate-mefloquine combination therapy in patients with uncomplicated Plasmodium falciparum malaria in Thailand

The aim of this study was to investigate the association between genetic polymorphisms of Plasmodium falciparum chloroquine resistance transporter (pfcrt), P. falciparum multidrug resistance 1 (pfmdr1), and P. falciparum ATPase (pfatp6) and clinical outcome after a three-day mefloquine-artesunate combination therapy in 134 patients with uncomplicated Plasmodium falciparum malaria in an area with multidrug resistance along the Thailand-Myanmar border. Analysis of gene mutation and amplification were performed by nested real-time polymerase chain reaction and SYBR Green I real-time polymerase chain reaction, respectively. The mutation for pfcrt (codons 76, 220, 271, 326, 356, and 371) was found in all isolates (100%), whereas no mutation of pfmdr1 (codon 86) and pfatp6 (codons 37, 693, 769, 898) was found. The Pfmdr1 copy number was significantly higher in isolates with recrudescence (median number = 2.44) compared with a sensitive response (median number = 1.44). The gene copy number was also found to be significantly higher in paired isolates collected before treatment and at the time of recrudescence. All isolates carried one pfatp6 gene copy.     

Possible chloroquine-resistant Plasmodium falciparum in Nigeria.

A 42-year-old hospital worker had a recrudescence of falciparum malaria after chloroquine therapy. Further adequate treatment with chloroquine given orally did not clear the infection. He was then given a combination of sulphadiazine and pyrimethamine, which produced a radical cure. This points to the possibility of chloroquine-resistant Plasmodium falciparum in Nigeria, an African country where this has been thought to be unlikely. Because of this and earlier reports, clinicians should be on the alert to the possibility of chloroquine-resistant P. falciparum in this area, and efforts should be made to establish or reject the presence of malarial parasites resistant to chloroquine in Africa.     

Clinical and parasitological characteristics of puerperal malaria

BACKGROUND: Women with semi-immunity to malaria who live in regions where the disease is endemic are at increased risk for more frequent and severe episodes of malaria during pregnancy. Recent findings indicate that this increased risk might persist beyond delivery, but the underlying mechanisms for this change in risk are poorly understood. METHODS: One hundred fifty women were included in a cohort study in Lambaréné, Gabon, and were actively followed up weekly for 10 weeks after delivery, as were nonpregnant control women who had been matched to them by location and age. Parasites in samples of placenta and blood were genotyped by use of polymerase chain reaction amplification of the merozoite surface antigen 2 gene and the subtelomeric variable open reading frame gene of Plasmodium falciparum. RESULTS: Eleven puerperal women had cases of clinical malaria, compared with 1 control woman (rate ratio, 9.8; P=.006). Eighteen puerperal women had P. falciparum parasitemia, compared with 6 control women (rate ratio, 2.7; P=.03). Five of 16 puerperal women (31%) with parasitemia on follow-up had identical parasites in their placentas and blood, and 11 of these cases (69%) were the result of reinfection. Puerperal women remained at equal risk for the development of parasitemia throughout the first 10 weeks after delivery. Use of bed nets, use of chloroquine prophylaxis during pregnancy, presence of malaria episodes during pregnancy, gravidity, and age were not associated with the acquisition of parasitemia during follow-up. CONCLUSIONS: Compared with nonpregnant women, puerperal women have a considerably increased risk for the development of malaria and/or parasitemia. This increased risk is caused both by the recurrence of P. falciparum parasitemia and by the increased susceptibility to new infections, although the latter plays a more significant role.     

Detection of histidine rich protein 2 and panmalarial ICT Malaria Pf/Pv test antigens after chloroquine treatment of uncomplicated falciparum malaria does not reliably predict treatment outcome in eastern Indonesia.

In regions with drug-resistant malaria, the ability to rapidly detect or predict treatment failure (TF) soon after a course of standard therapy for Plasmodium falciparum malaria would facilitate the prompt institution of second-line therapy. We thus evaluated longitudinally the ability of the ICT Malaria Pf/Pv immunochromatographic test to predict treatment outcome. Sixty-six Sumbanese Indonesians with uncomplicated falciparum malaria were treated with chloroquine and followed for 28 days by use of 1997 World Health Organization criteria for assessment of therapeutic efficacy of antimalarial drugs. The ICT Pf/Pv testing could be compared with microscopy in approximately half of the patients on each day of follow-up. Although strongly positive histidine rich protein 2 (HRP2) line intensities (equal to or greater than the control band) in convalescence were highly predictive of TF, any degree of positivity for the HRP2 and panmalarial antigens in convalescence was only moderately predictive of TE Positive predictive values of the HRP2 and panmalarial antigens for TF were 76.9% and 87.0%, respectively, on Day 3, 82.4% and 87.5% on Day 7, and 78.9% and 78.9% on Day 14. Negative HRP2 and panmalarial antigen results in convalescence were even less predictive of an adequate clinical response, and false-negative HRP2 and panmalarial antigen test results were found in one-sixth (6 of 37) of recrudescent infections diagnosed by microscopy among patients with late treatment failure. To reliably predict treatment outcome with rapid antigen tests, further development appears necessary to improve sensitivity for viable asexual parasites while avoiding detection of both gametocytes and persistent antigen in convalescence.     

High rates of recurrence and of transient reinfections of Helicobacter pylori in a population with high prevalence of infection

OBJECTIVES: Little is known concerning the magnitude of reinfection versus recrudescence of Helicobacter pylori (H. pylori) infection after eradication treatment. The aims of this study were to determine the magnitude of H. pylori reinfection versus recrudescence, and to identify possible risk factors for reinfection. METHODS: Children and adults with upper GI symptoms treated at the Centro Médico Nacional Siglo XXI (Instituto Mexicano del Seguro Social, in Mexico City, Mexico) were studied. H. pylori infection was diagnosed with urea breath test (UBT), histology, and culture. Infected patients received triple therapy, and those who became UBT negative 4-6 wk after treatment were considered as eradicated and were included in the study. A cohort of 141 patients in whom the disease was eradicated was monitored for recurrence with UBT at 3, 6, 9, 12, 18, and 24 months. H. pylori was isolated from gastric biopsy samples before treatment and at recurrence and isolates compared by genotyping. RESULTS: During this period, 32 (22.7%) cases of recurrence were documented the majority occurring during yr 1. In nine of the 32 (28.1%) cases, recurrence was eradicated spontaneously, suggesting these were transient reinfections. Recurrence rates were significantly higher in the subjects 41-60 yr of age than in younger or older subjects. H. pylori isolates from 12 recurrence cases were genotyped; nine (75%) were classified as true reinfection and three as recrudescence. CONCLUSIONS: In our population, recurrence rate is high in adults and transient reinfection is common. In several cases, reinfection occurred by multiple strains, which suggests that soon after eradication, patients are exposed to multiple sources of reinfection.     

Clindamycin for the treatment of falciparum malaria in Sudan

Clindamycin, 5 mg/kg twice a day for 5 days, was used to treat falciparum malaria after clinical and parasitological diagnosis at a health station in Faki Hashim, a suburb of Khartoum, Sudan. Twenty out of twenty-six patients enrolled completed the study. Giemsa-stained thick blood films were negative for asexual parasites by day 7 in 17 patients and by day 8 in the remaining 3. All were examined on days 14 or 28; 2 who had initially been cleared by day 6 had asymptomatic low density asexual parasitemia on day 14, which disappeared without treatment by day 28, and 2 others initially cleared by day 5 were similarly positive at day 28. Reinfection in these patients cannot be ruled out. Of the 6 patients withdrawn from the study, 2 took chloroquine independently, 1 developed vomiting, 1 developed diarrhea, 1 acquired a circumoral maculopapular rash, and 1 had an increasing parasitemia on day 3 and was switched to chloroquine. Generally, the treatment was without toxicity and was well received. Clindamycin proved satisfactory for the treatment of simple cases of falciparum malaria in the field in Africa.     

Plasmodium falciparum reinfection in children from a holoendemic area in relation to seroreactivities against oligopeptides from different malaria antigens.

The rate and densities of Plasmodium falciparum reinfections were investigated in children five to 14 years old from one village in Tanzania with a high transmission rate. Initial parasitemias were eradicated by a curative treatment with quinine, a drug with a short elimination half-life, to minimize the effects of residual drug on reinfection. The seroreactivities to seven oligopeptides, representing T and B cell epitopes from the ring erythrocyte surface antigen (Pf155/RESA), the clustered arginine-rich protein antigen (CARP), and the circumsporozoite (CS) proteins were determined in the children at the start of the study and after 28 days. All children were reinfected within 42 days (mean 27 days). The geometric mean maximum parasite density at reinfection was 308 parasites per microliter (range 4-13, 920). The antipeptide antibody levels showed high interindividual variation, with a significant mean decrease (16%) between days 0 and 28 for the blood stage antigens, but not for the (NANP)6 peptide from the CS protein. This suggests that the absence of blood stage antigenic stimulation had already influenced the antibody levels within this short period of time. The mean reinfection day was not influenced by the levels of antibodies to any of the peptides. However, the children with higher antibody levels to (EENVEHDA)2(EENV)2 developed significantly lower parasitemias than those with lower antibody levels (P less than 0.05). This suggests that this subunit of the Pf155/RESA molecule is an important B cell epitope for protective antiparasitic immunity.     

Short report: Field evaluation of posttreatment sensitivity for monitoring parasite clearance of Plasmodium falciparum malaria by use of the Determine Malaria pf test in central India

The posttreatment performance of the Plasmodium falciparum histidine-rich protein rapid diagnostic test Determine Malaria pf (Abbott Laboratories, Tokyo, Japan) was assessed in 70 patients in central India with uncomplicated falciparum malaria who were treated with chloroquine, sulfadoxine-pyrimethamine, and arteether. Data were compared with those of microscopy. Results revealed that the sensitivity for predicting recrudescence by means of the Determine test after treatment with chloroquine on Day 14 was 75%, with 50% specificity. However, antigenemia was detected in 16% of patients as late as Day 21 in sulfadoxine-pyrimethamine-treated subjects with a drug-sensitive response. Clearance of parasitemia in thick blood smear and clearance of antigenemia appeared to parallel each other only in arteether-treated subjects. The observed diagnostic trends therefore mean that the potential of the Determine test to detect recrudescent infection is limited.     

Helicobacter pylori reinfection with identical organisms: transmission by the patients' spouses.

Reinfection with Helicobacter pylori after eradication is responsible for the recurrence of duodenal ulcer disease. The mode of transmission has not yet been established. In this study, 18 patients with chronic duodenal ulcers in whom H pylori had been eradicated with amoxicillin and metronidazole were entered into a prospective follow up study. Control endoscopies were performed 4, 8, 14, 27, and 43 months after starting treatment and the results of direct tests were compared with the kinetics of H pylori specific IgG titres. After eradication there was a noticeable and consistent fall in anti-H pylori IgG, while reinfections were characterised by a significant increase in specific titres. Reinfection was detected in two patients after 14 and 43 months, respectively. The H pylori strains responsible for these reinfections, the corresponding pretreatment isolates, and the strains isolated from the spouses of these patients were examined by polymerase chain reaction based DNA fingerprinting. Analysis showed that reinfection had been caused by the same H pylori strain and identified the spouses of these patients as carriers of the identical strain. Considering the genomic diversity and the interpatient heterogeneity of H pylori these results suggest a person to person transmission of H pylori reinfection. By the end of the observation period reflux oesophagitis had developed in 10 of the 16 patients who had not been reinfected. This surprising finding may be explained by the changed eating habits of patients after healing of duodenal ulcer disease.     

A study of experimental reinfection by Trypanosoma cruzi in dogs.

The role of reinfection in the evolution of Chagas' disease was evaluated in dogs alternately infected with the 147 and SC-1 strains of Trypanosoma cruzi. A parasitologic, serologic, clinical, and electrocardiographic follow-up was carried out on the infected and noninfected dogs. The dogs were reinfected five times over a period of 38 months. No deaths were observed during the experiment. They presented a brief oligosymptomatic acute phase. The level of parasitemia decreased progressively with the number of reinfections. Bloodstream parasites were not detectable after the fifth reinfection. All parasite samples isolated during the follow-up were zymodeme B, corresponding to strain 147, irrespective of the strain with which the dogs were first infected and of the triatomine species used for isolation. Conversely, amplification by the polymerase chain reaction of a segment of the T. cruzi mini-exon gene showed the simultaneous presence of both strains in three of the eight reinfected animals. Antibody titers were greater among the dogs successively infected than those infected only once. Neither amastigotes nor T. cruzi DNA were detected in the tissues of the infected dogs. Alterations related to Chagas' disease were identified only in the heart and consisted of chronic focal and discrete myocarditis, compatible with the indeterminate form of Chagas' disease. All infected dogs developed this form of the disease, which was independent of the number of infections.     

A double-blind, randomized study of azithromycin compared to chloroquine for the treatment of Plasmodium vivax malaria in India

Azithromycin has demonstrated activity in a prevention of Plasmodium vivax infection, but no controlled treatment studies have been performed. We conducted a double-blinded trial in P. vivax malaria in which patients were randomized to either azithromycin 1,000 mg q.d. x 3 or chloroquine 600 mg q.d. x 2 then 300 mg on Day 3 followed by primaquine on Days 7 through 20. Eighty-five of 97 (88%) of those on azithromycin and 101 of 102 (99%) of those on chloroquine [difference 11%; 95% CI: -18, -4] were clinically cured at Day 7. The Day 28 results were similar [89% versus 99%, azithromycin versus chloroquine, respectively]. Parasitologic success was seen in 81 of 97 (84%) on azithromycin and 100 of 102 (98%) on chloroquine [difference 14%; 95% CI: -22, -6]. The median parasite clearance time was 55 hours on azithromycin and 20 hours on chloroquine (P < 0.001). Drug-related adverse events were seen in 13 of 98 (13%) on azithromycin and 24 of 102 (24%) on chloroquine (P = 0.062). Resolution of parasitemia was significantly faster with chloroquine compared with azithromycin, but azithromycin was better tolerated. These data provide support for further study of azithromycin to better define its role in the treatment of P. vivax malaria, either alone as second-line treatment or in combination with other active therapies.