Spread of artemisinin resistance in Plasmodium falciparum malaria

BACKGROUND

Artemisinin resistance in Plasmodium falciparum has emerged in Southeast Asia and now poses a threat to the control and elimination of malaria. Mapping the geographic extent of resistance is essential for planning containment and elimination strategies.

METHODS

Between May 2011 and April 2013, we enrolled 1241 adults and children with acute, uncomplicated falciparum malaria in an open-label trial at 15 sites in 10 countries (7 in Asia and 3 in Africa). Patients received artesunate, administered orally at a daily dose of either 2 mg per kilogram of body weight per day or 4 mg per kilogram, for 3 days, followed by a standard 3-day course of artemisinin-based combination therapy. Parasite counts in peripheral-blood samples were measured every 6 hours, and the parasite clearance half-lives were determined.

RESULTS

The median parasite clearance half-lives ranged from 1.9 hours in the Democratic Republic of Congo to 7.0 hours at the Thailand-Cambodia border. Slowly clearing infections (parasite clearance half-life >5 hours), strongly associated with single point mutations in the "propeller" region of the P. falciparum kelch protein gene on chromosome 13 (kelch13), were detected throughout mainland Southeast Asia from southern Vietnam to central Myanmar. The incidence of pretreatment and post-treatment gametocytemia was higher among patients with slow parasite clearance, suggesting greater potential for transmission. In western Cambodia, where artemisinin-based combination therapies are failing, the 6-day course of antimalarial therapy was associated with a cure rate of 97.7% (95% confidence interval, 90.9 to 99.4) at 42 days.

CONCLUSIONS

Artemisinin resistance to P. falciparum, which is now prevalent across mainland Southeast Asia, is associated with mutations in kelch13. Prolonged courses of artemisinin-based combination therapies are currently efficacious in areas where standard 3-day treatments are failing. (Funded by the U.K. Department of International Development and others; ClinicalTrials.gov number, NCT01350856.).

Declining efficacy of artesunate plus sulphadoxine-pyrimethamine in northeastern India

BACKGROUND

Anti-malarial drug resistance in Plasmodium falciparum in India has historically travelled from northeast India along the Myanmar border. The treatment policy for P. falciparum in the region was, therefore, changed from chloroquine to artesunate (AS) plus sulphadoxine-pyrimethamine (SP) in selected areas in 2005 and in 2008 it became the first-line treatment. Recognizing that resistance to the partner drug can limit the useful life of this combination therapy, routine in vivo and molecular monitoring of anti-malarial drug efficacy through sentinel sites was initiated in 2009.

METHODS

Between May and October 2012, 190 subjects with acute uncomplicated falciparum malaria were enrolled in therapeutic efficacy studies in the states of Arunachal Pradesh, Tripura, and Mizoram. Clinical and parasitological assessments were conducted over 42 days of follow-up. Multivariate analysis was used to determine risk factors associated with treatment failure. Genotyping was done to distinguish re-infection from recrudescence as well as to determine the prevalence of molecular markers of antifolate resistance among isolates.

RESULTS

A total of 169 patients completed 42 days of follow-up at three sites. The crude and PCR-corrected Kaplan-Meier survival estimates of AS + SP were 60.8% (95% CI: 48.0-71.4) and 76.6% (95% CI: 64.1-85.2) in Gomati, Tripura; 74.6% (95% CI: 62.0-83.6) and 81.7% (95% CI: 69.4-89.5) in Lunglei, Mizoram; and, 59.5% (95% CI: 42.0-73.2) and 82.3% (95% CI: 64.6-91.6) in Changlang, Arunachal Pradesh. Most patients with P. falciparum cleared parasitaemia within 24 hours of treatment, but eight, including three patients who failed treatment, remained parasitaemic on day 3. Risk factors associated with treatment failure included age < five years, fever at the time of enrolment and AS under dosing. No adverse events were reported. Presence of dhfr plus dhps quintuple mutation was observed predominantly in treatment failure samples.

CONCLUSION

AS + SP treatment failure was widespread in northeast India and exceeded the threshold for changing drug policy. Based on these results, in January 2013 the expert committee of the National Vector Borne Disease Control Programme formulated the first subnational drug policy for India and selected artemether plus lumefantrine as the new first-line treatment in the northeast. Continued monitoring of anti-malarial drug efficacy is essential for effective malaria control.

Chloroquine efficacy studies confirm drug susceptibility of Plasmodium vivax in Chennai, India

Background

Assessing the Plasmodium vivax burden in India is complicated by the potential threat of an emerging chloroquine (CQ) resistant parasite population from neighbouring countries in Southeast Asia. Chennai, the capital of Tamil Nadu and an urban setting for P. vivax in southern India, was selected as a sentinel site for investigating CQ efficacy and sensitivity in vivax malaria.

Methods

CQ efficacy was evaluated with a 28-day in vivo therapeutic study, while CQ sensitivity was measured with an in vitro drug susceptibility assay. In both studies, isolates also underwent molecular genotyping to investigate correlations between parasite diversity and drug susceptibility to CQ. Molecular genotyping included sequencing a 604 base pair (bp) fragment of the P. vivax multidrug resistant gene-1 (Pvmdr1) for single nucleotide polymorphisms (SNPs) and also the amplification of eight microsatellite (MS) loci located across the genome on eight different chromosomes.

Results

In the 28-day in vivo study (N=125), all subjects were aparasitaemic by Day 14. Passive case surveillance continuing beyond Day 28 in 22 subjects exposed 17 recurrent infections, which ranged from 44 to 148 days post-enrollment. Pvmdr1 sequencing of these recurrent infections revealed that 93.3% had identical mutant haplotypes (958M/Y976/1076L) to their baseline Day 0 infection. MS genotyping further revealed that nine infection pairs were related with ≥75% haplotype similarity (same allele at six or more loci). To test the impact of this mutation on CQ efficacy, an in vitro drug assay (N=68) was performed. No correlation between IC₅₀ values and the percentage of ring-stage parasites prior to culture was observed (r_sadj: -0.00063, p = 0.3307) and the distribution of alleles among the Pvmdr1 SNPs and MS haplotypes showed no significant associations with IC₅₀ values.

Conclusions

Plasmodium vivax was found to be susceptible to CQ drug treatment in both the in vivo therapeutic drug study and the in vitro drug assay. Though the mutant 1076L of Pvmdr1 was found in a majority of isolates tested, this single mutation did not associate with CQ resistance. MS haplotypes revealed strong heterogeneity in this population, indicating a low probability of reinfection with highly related haplotypes.

Antimalarial drug policy in India: past, present & future

The use of antimalarial drugs in India has evolved since the introduction of quinine in the 17 th century. Since the formal establishment of a malaria control programme in 1953, shortly after independence, treatments provided by the public sector ranged from chloroquine, the mainstay drug for many decades, to the newer, recently introduced artemisinin based combination therapy. The complexity of considerations in antimalarial treatment led to the formulation of a National Antimalarial Drug Policy to guide procurement as well as communicate best practices to both public and private healthcare providers. Challenges addressed in the policy include the use of presumptive treatment, the introduction of alternate treatments for drug-resistant malaria, the duration of primaquine therapy to prevent relapses of vivax malaria, the treatment of malaria in pregnancy, and the choice of drugs for chemoprophylaxis. While data on antimalarial drug resistance and both public and private sector treatment practices have been recently reviewed, the policy process of setting national standards has not. In this perspective on antimalarial drug policy, this review highlights its relevant history, analyzes the current policy, and examines future directions.

Prevalence of torus palatinus and torus mandibularis among Malay population

The aims of this study were to determine the prevalence, size, shape, and location of torus palatinus (TP) and torus mandibularis (TM), and to assess their sex-related and age-related differences in the Malay population. Sixty-five subjects were assessed for the presence of both tori at the School of Dental Sciences University Sains Malaysia. The prevalence of TP was 38–63% and that of TM was 1–10%. TP was frequently more common in females than males (90.9% versus 9.1%; P < 0.05) and was frequently found in medium sizes, spindle shaped, and was often located at the combined premolar to molar areas. The prevalence of TM was not significantly different in males and females (33.3% versus 66.7%; P = 0.523), occurred most commonly in bilateral multiple form, and was often located at the canine to premolar area.

Insights following change in drug policy: a descriptive study for antimalarial prescription practices in children of public sector health facilities in Jharkhand state of India

BACKGROUND & OBJECTIVES

Widespread resistance to chloroquine was the mainstay to implement artemisinin-based combination therapy (ACT) in the year 2007 in few malaria endemic states in India including Jharkhand as the first line of treatment for uncomplicated Plasmodium falciparum malaria. This study was conducted in Jharkhand state of the country just after the implementation of ACT to assess the prevailing antimalarial drug prescribing practices, availability of antimalarial drugs and the acceptability of the new policy by the health professionals for the treatment of uncomplicated P. falciparum malaria patients particularly in children ≤ 15 yr of age.

METHODS

This is a cross-sectional study in children aged ≤ 15 yr with malaria or to whom antimalarial drug was prescribed. Main outcome measure was prescription of recommended ACT in children aged ≤ 15 yr with malaria in the selected areas of Jharkhand.

RESULTS

In the year 2008, artemisinin-based combination therapy (ACT) was implemented in 12 districts of the studied state; however, the availability of ACT was confirmed only in five districts. Antimalarial prescription was prevalent amongst the undiagnosed (8.4%), malaria negative (64.3%) and unknown blood test result (1.2%) suggesting the prevalence of irrational treatment practices. ACT prescription was very low with only 3.2% of confirmed falciparum malaria patients receiving it while others received either non-artesunate (NA) treatment (88.1%) including chloroquine (CQ) alone, CQ + Primaquine (PQ)/other drugs, sulphadoxine-pyrimethamine (SP) alone, SP + other drugs or artemisinin monotherapy (AM) treatment (6.3%). Still others were given non-antimalarial treatment (NM) in both malaria positive (0.3%) and malaria negative (2.1%) cases.

INTERPRETATION & CONCLUSION

Despite the change in drug policy in the studied state the availability and implementation of ACT was a major concern. Nevertheless, the non-availability of blister packs for children aged ≤ 15 yr was the main hindrance in the implementation of the recommended antimalarial. Availability, training and participation of health professionals in decision-making are the key elements to improve adherence to new treatment guidelines. This study provided evidence for the requirement of age-specific blister packs in the country and the national programme has introduced age-specific blister packs in the country in 2010. This baseline information will be useful to monitor the progress in ACT implementation in the country.

Intraosseous acinic cell carcinoma

Acinic cell carcinoma is an uncommon low-grade malignant tumor of salivary glands. It was first described by Nasse in 1892, arising in parotid salivary gland. Salivary gland tumors are also known to develop within jaw bones, arising within the jaw as a primary central lesion, and are extremely rare with only a few cases reported. We present a rare case report of 65-year-old woman with intraosseous acinic cell carcinoma of left side of the mandible.

A clinical and molecular study of artesunate + sulphadoxine-pyrimethamine in three districts of central and eastern India

Background

Artesunate + sulphadoxine-pyrimethamine (AS + SP) is recommended throughout India as the first-line treatment for uncomplicated falciparum malaria. Due to the presence of several eco-epidemiological zones of malaria and variable drug pressure, it is necessary to evaluate the efficacy of this combination in different regions of India. The objective of this study was to use clinical and molecular methods to monitor the efficacy of AS + SP in three diverse sites.

Methods

The study was undertaken in three high endemic sites of central and eastern India. Patients with uncomplicated falciparum malaria were enrolled and followed for 28 days. Molecular genotyping was conducted for merozoite surface protein (msp1 and msp2) to differentiate between re-infection and recrudescence and for the dhfr and dhps genes to monitor antifolate drug resistance.

Results

In all, 149 patients were enrolled at the three sites. The crude cure rates were 95.9%, 100%, and 100% in Ranchi, Keonjhar, and West Garo Hills respectively. PCR-corrected cure rates were 100% at all sites. In dhfr, 27% of isolates had triple mutations, while 46% isolates were double-mutants. The most prevalent mutation was S108N followed by C59R. 164 L mutation was observed in 43/126 (34%) isolates. In dhps, most (76%) of the isolates were wild-type. Only 2.5% (2/80) isolates showed double mutation. dhfr-dhps two locus mutation were observed in 16% (13/80) isolates. Parasite clearance time was not related with antifolate mutations.

Conclusions

AS + SP combination therapy remained effective against falciparum malaria despite common mutations promoting resistance to antifolate drugs. Although the prevalence of double and triple mutations in dhfr was high, the prevalence of dhfr-dhps two locus mutations were low. Even isolates with dhfr triple and dhfr-dhps two locus mutations achieved adequate clinical and parasitological response.

Epidemiology of Plasmodium falciparum gametocytemia in India: prevalence, age structure, risk factors and the role of a predictive score for detection

OBJECTIVE

To characterise the epidemiology of Plasmodium falciparum gametocytemia and determine the prevalence, age structure and the viability of a predictive model for detection.

METHODS

We collected data from 21 therapeutic efficacy trials conducted in India during 2009-2010 and estimated the contribution of each age group to the reservoir of transmission. We built a predictive model for gametocytemia and calculated the diagnostic utility of different score cut-offs from our risk score.

RESULTS

Gametocytemia was present in 18% (248/1 335) of patients and decreased with age. Adults constituted 43%, school-age children 45% and under fives 12% of the reservoir for potential transmission. Our model retained age, sex, region and previous antimalarial drug intake as predictors of gametocytemia. The area under the receiver operator characteristic curve was 0.76 (95%CI:0.73,0.78), and a cut-off of 14 or more on a risk score ranging from 0 to 46 provided 91% (95%CI:88,95) sensitivity and 33% (95%CI:31,36) specificity for detecting gametocytemia.

CONCLUSIONS

Gametocytemia was common in India and varied by region. Notably, adults contributed substantially to the reservoir for potential transmission. Predictive modelling to generate a clinical algorithm for detecting gametocytemia did not provide sufficient discrimination for targeting interventions.

Genetic variety of bovine viral diarrhea virus 1 strains isolated from sheep and goats in India

Antigenic and genetic typing of pestiviruses isolated from Indian sheep and goats was carried out. Testing of 1777 sheep and 1026 goat blood samples collected between 2004 and 2008 resulted in isolation of twelve pestiviruses, seven from sheep and five from goats. All of them were antigenically typed as bovine viral diarrhea virus 1 (BVDV-1). Both the partial 5ʹ-UTR and entire non-structural autoprotease (Npro) gene of the pestiviruses were amplified by RT-PCR and sequenced. The phylogenetic analysis confirmed all twelve sheep and goat pestiviruses as BVDV-1 and they were further classified into two subtypes, BVDV-1b (seven) and BVDV-1c (five). This is for the first time that BVDV-1c was detected in sheep and goats. However, no association between the subtype and geographic area of origin was observed. Although closely related, BVDV-1b and BVDV-1c isolates of sheep and goats were placed in a different clade than previously reported Indian BVDV-1b/BVDV-1c isolates. This study confirmed widespread prevalence of BVDV-1 in Indian sheep and goats that has significance in the epidemiology of bovine viral diarrhea.

KEYWORDS

bovine viral diarrhea virus; BVDV-1; goat; Npro; genetic typing; sheep; 5ʹ-UTR.

Genetic deletion of HRP2 and HRP3 in Indian Plasmodium falciparum population and false negative malaria rapid diagnostic test

Genetic polymorphisms in diagnostic antigens are important factors responsible for variable performance of rapid diagnostic tests. Additionally, the failure of antigen expression due to gene deletion may also contribute to variable performance. We report Indian Plasmodium falciparum field isolates lacking both Pfhrp2 and Pfhrp3 genes leading to false negative results of rapid diagnostic tests. The study highlights need to determine the prevalence of P. falciparum isolates lacking these genes in larger field populations in India.

Quercetin modulates Na(+)/K(+) ATPase and sodium hydrogen exchanger in type 2 diabetic erythrocytes

Quercetin has been reported to possess many important biological properties. We undertook in vitro studies to examine the effect of quercetin on erythrocyte Na(+)/K(+) ATPase and sodium hydrogen exchanger (NHE) activity in normal and type 2 diabetic subjects. A significant (p<0.02) increase in the activities of Na(+)/K(+) ATPase and a decrease (p< 0.01) in NHE were observed in type 2 diabetic subjects compared to normal. In vitro treatment with quercetin caused inhibition of both Na(+)/K(+) ATPase and NHE. The inhibitory effect of quercetin was concentration dependent. The effect of quercetin on Na(+)/K(+) ATPase and NHE may be explained due to a direct effect of this compound on plasma membrane leading to a change in membrane fluidity. The data obtained in this study may help to explain the anti—diabetic and anti—carcinogenic role of quercetin.

Monitoring antimalarial drug resistance in India via sentinel sites: outcomes and risk factors for treatment failure, 2009-2010

OBJECTIVE

To describe India's National Antimalarial Drug Resistance Monitoring System, measure the efficacy of first-line malaria treatments, and determine risk factors for treatment failure.

METHODS

In 2009-2010, prospective studies with 28 days of follow-up were conducted at 25 sentinel sites. Patients infected with Plasmodium falciparum were given artesunate plus sulfadoxine-pyrimethamine (AS+SP); those infected with P. vivax were given chloroquine. Polymerase chain reaction was used to distinguish post-treatment reinfection from treatment failure. Isolates of P. falciparum were checked for dhfr and dhps mutations.

FINDINGS

Overall, 1664 patients were enrolled. Kaplan-Meier survival analysis showed an efficacy of 98.8% for AS+SP. Most patients with P. falciparum parasitaemia cleared their parasitaemias within 24 hours of treatment initiation, but six, including four with treatment failure, remained parasitaemic after 72 hours. Double mutants in dhfr were found in 68.4% of the genotyped isolates. Triple or quadruple mutants in dhfr and mutations in dhps were rare. A daily dose of artesunate of < 3 mg per kg of body weight, age of less than 5 years, and fever at enrolment were associated with an increased risk of treatment failure. Chloroquine remained 100% efficacious and generally cleared P. vivax parasitaemias within 48 hours. Vomiting (seen in 47 patients) was the most common adverse event.

CONCLUSION

India's National Antimalarial Drug Resistance Monitoring System provides wide coverage. The first-line antimalarials used in the country remain safe and efficacious. The treatment of malaria in young children and the relative benefits of age- and weight-based dosing need further exploration.

Genetic variation in histidine rich proteins among Indian Plasmodium falciparum population: possible cause of variable sensitivity of malaria rapid diagnostic tests

Background

Rapid diagnostic tests (RDTs) have revolutionized the diagnosis of malaria. Among the various factors affecting RDTs sensitivity is genetic variation of the antigen used. The genetic variation in PfHRP2 and PfHRP3 proteins was studied among the Indian Plasmodium falciparum isolates.

Methods

One hundred and forty isolates of P. falciparum were collected from six geographical regions of India. Target genes encoding PfHRP2 and PfHRP3 antigens were sequenced to study genetic polymorphism. Minimum detection limit giving a positive rapid diagnostic test was also determined.

Results

Extensive variations were observed in amino acid repeat types of PfHRP2 and PfHRP3. PfHRP2 exhibited more polymorphism than PfHRP3. Significant relation was observed between type 2 and type 7 repeats and RDT detection rate as higher number of these repeats showed better sensitivity with RDTs.

Conclusion

The results provide insights into the genetic diversity of Pfhrp2 and Pfhrp3 genes among Indian P. falciparum population and its relation to RDT sensitivity.

Laparoscopic vertical sleeve gastrectomy after open gastric banding in a patient with situs inversus totalis

While several equivalent alternatives are available in the bariatric algorithm, more recently the laparoscopic sleeve gastrectomy (SG) has been gaining traction as an effective means of weight loss in patients with morbid obesity. We present the case of a 39-year-old woman with situs inversus totalis, who was taken to the operating room for laparoscopic SG. The patient had previously undergone a failed open gastric banding procedure 20 months earlier. Awareness of the inherited condition before performing the operation allows for advanced planning and preparation. Subsequent modifications to the standard trocar placement help make the procedure more technically feasible. To our knowledge, this is the first published report of a laparoscopic SG after open gastric banding in a patient with situs inversus totalis. After encountering the initial disorientation, we believe experienced laparoscopic surgeons can perform this procedure successfully and safely.

Increased zymogen activity of thrombin-activatable fibrinolysis inhibitor prolongs clot lysis

BACKGROUND AND OBJECTIVES

Thrombin-activatable fibrinolysis inhibitor (TAFI) is a zymogen that can be activated by proteolytic cleavage into the active enzyme TAFIa. Hydrolysis of the C-terminal lysines on fibrin by TAFIa results in a down-regulation of fibrinolysis. Recent studies demonstrated that the zymogen also exerts an intrinsic enzymatic activity. Our objective was to identify and characterize zymogen-stimulatory nanobodies.

METHODS AND RESULTS

The screening of 24 nanobodies against TAFI revealed that two nanobodies (i.e. Vhh-TAFI-a51 and Vhh-TAFI-i103) were able to stimulate the zymogen activity 10- to 21-fold compared with the baseline zymogen activity of TAFI. The increase in catalytic efficiency can be attributed mainly to an increased catalytic rate, as no change in the K(M) -value was observed. The stability, the susceptibility towards PTCI and GEMSA and the kinetics of the stimulated zymogen activity differ significantly from those of TAFIa activity. Epitope mapping revealed that both Asp(75) and Thr(301) are major determinants in the binding of these nanobodies to TAFI. Localization of the epitope strongly suggests that this instability is as a result of a disruption of the stabilizing interactions between the activation peptide and the dynamic flap region (residues 296-350). In TAFI-depleted plasma reconstituted with a non-activatable variant of TAFI (TAFI-R92A), clot lysis could be prolonged by nanobody-induced stimulation of its zymogen activity as well as by increasing its concentration.

CONCLUSIONS

Increasing the zymogen activity of TAFI results in an antifibrinolytic effect.

Prescription practices and availability of artemisinin monotherapy in India: where do we stand?

BACKGROUND

The World Health Organization has urged all member states to deploy artemisinin-based combination therapy and progressively withdraw oral artemisinin monotherapies from the market due to their high recrudescence rates and to reduce the risk of drug resistance. Prescription practices by physicians and the availability of oral artemisinin monotherapies with pharmacists directly affect the pattern of their use. Thus, treatment practices for malaria, with special reference to artemisinin monotherapy prescription, in selected states of India were evaluated.

METHODS

Structured, tested questionnaires were used to conduct convenience surveys of physicians and pharmacists in eleven purposively selected districts across six states in 2008. In addition, exit interviews of patients with a diagnosis of uncomplicated malaria or a prescription for an anti-malarial drug were also performed. Logistic regression was used to determine patient clinical care, and institutional factors associated with artemisinin monotherapy prescription.

RESULTS

Five hundred and eleven physicians from 196 health facilities, 530 pharmacists, and 1,832 patients were interviewed. Artemisinin monotherapy was available in 72.6% of pharmacies and was prescribed by physicians for uncomplicated malaria in all study states. Exit interviews among patients confirmed the high rate of use of artemisinin monotherapy with 14.8% receiving such a prescription. Case management, i.e. method of diagnosis and overall treatment, varied by state and public or private sector. Treatment in the private sector (OR 8.0, 95%CI: 3.8, 17) was the strongest predictor of artemisinin monotherapy prescription when accounting for other factors. Use of the combination therapy recommended by the national drug policy, artesunate + sulphadoxine-pyrimethamine, was minimal (4.9%), with the exception of one state.

CONCLUSIONS

Artemisinin monotherapy use was widespread across India in 2008. The accessible sale of oral artemisinin monotherapy in retail market and an inadequate supply of recommended drugs in the public sector health facilities promoted its prescription. This study resulted in notifications to all state drug controllers in India to withdraw the oral artemisinin formulations from the market. In 2010, artesunate + sulphadoxine-pyrimethamine became the universal first-line treatment for confirmed Plasmodium falciparum malaria and was deployed at full scale.