Orthostatic hypotension in Parkinson's disease: Sit-to-stand vs. supine-to-stand protocol and clinical correlates

BACKGROUND

Screening for orthostatic hypotension (OH) is integral in Parkinson's disease (PD) management, yet evidence-based guidelines on best practice methods for diagnosing OH in PD are lacking.

METHODS

We investigated the frequency and correlates of OH, symptomatic OH, and neurogenic OH, in a large consecutively recruited PD cohort (n = 318), and compared the diagnostic performance of the sit-to-stand vs. the supine-to-stand blood pressure (BP) test. We evaluated the utility of continuous BP monitoring and tilt table testing in patients with postural symptoms or falls who were undetected to have OH with clinic-based BP measurements. Disease severity, fluid intake, orthostatic and overactive bladder symptoms, falls, comorbidities and medication history were evaluated.

RESULTS

Patients' mean age was 66.1 ± 9.5years, with mean disease duration 7.8 ± 5.5years. OH frequency was 35.8 % based on the supine-to-stand test. OH in PD was significantly associated with older age, lower body mass index, longer disease duration, worse motor, cognitive and overactive bladder symptoms and functional disabilities, falls, and lower fluid intake. A similar profile was seen with asymptomatic OH. Three quarters of OH were neurogenic, with the majority also having supine hypertension. The sit-to-stand test had a sensitivity of only 0.39. One quarter of patients were additionally diagnosed with OH during continuous BP monitoring.

CONCLUSIONS

The sit-to-stand test substantially underdiagnoses OH in PD, with the important practice implication that supine-to-stand measurements may be preferred. Screening for OH is warranted even in asymptomatic patients. Adequate fluid intake, treatment of urinary dysfunction and falls prevention are important strategies in managing PD patients with OH.

Loss-of-function SMPD1 gene variant in Progressive Supranuclear Palsy-Richardson Syndrome patients of Chinese ancestry

Lysosomal dysfunction plays an important role in neurodegenerative diseases, including Parkinson's disease (PD) and possibly also Parkinson-plus syndromes such as progressive supranuclear palsy (PSP). This is exemplified by the involvement of the GBA1 gene, which results in a deficiency of the lysosomal enzyme glucocerebrosidase, and is currently the most frequently identified genetic factor underlying PD worldwide. Pathogenic variants in the SMPD1 gene are a recessive cause of Niemann-Pick disease type A and B. Here, we provide the first report on an association between a loss-of-function SMPD1 gene variant present in heterozygous state (p.Pro332Arg/p.P332R, which is known to result in reduced lysosomal acid sphingomyelinase activity), with PSP-Richardson syndrome in three unrelated patients of Chinese ancestry.

Genetic study of early-onset Parkinson's disease in the Malaysian population

BACKGROUND

About 5-10% of Parkinson's disease (PD) cases are early onset (EOPD), with several genes implicated, including GBA1, PRKN, PINK1, and SNCA. The spectrum and frequency of mutations vary across populations and globally diverse studies are crucial to comprehensively understand the genetic architecture of PD. The ancestral diversity of Southeast Asians offers opportunities to uncover a rich PD genetics landscape, and identify common regional mutations and new pathogenic variants.

OBJECTIVES

This study aimed to investigate the genetic architecture of EOPD in a multi-ethnic Malaysian cohort.

METHODS

161 index patients with PD onset ≤50 years were recruited from multiple centers across Malaysia. A two-step approach to genetic testing was used, combining a next-generation sequencing-based PD gene panel and multiplex ligation-dependent probe amplification (MLPA).

RESULTS

Thirty-five patients (21.7%) carried pathogenic or likely pathogenic variants involving (in decreasing order of frequency): GBA1, PRKN, PINK1, DJ-1, LRRK2, and ATP13A2. Pathogenic/likely pathogenic variants in GBA1 were identified in thirteen patients (8.1%), and were also commonly found in PRKN and PINK1 (11/161 = 6.8% and 6/161 = 3.7%, respectively). The overall detection rate was even higher in those with familial history (48.5%) or age of diagnosis ≤40 years (34.8%). PRKN exon 7 deletion and the PINK1 p.Leu347Pro variant appear to be common among Malay patients. Many novel variants were found across the PD-related genes.

CONCLUSIONS

This study provides novel insights into the genetic architecture of EOPD in Southeast Asians, expands the genetic spectrum in PD-related genes, and highlights the importance of diversifying PD genetic research to include under-represented populations.

Expanding the DARS phenotype: Late-adult onset myelopathy and leukoencephalopathy

A significant proportion of adult-onset neurological disorders remain diagnostic odysseys despite extensive evaluation. Hypomyelination with Brainstem and Spinal Cord Involvement and Leg Spasticity (HBSL) is an autosomal recessive disorder caused by mutations in the cytoplasmic aspartyl-tRNA synthetase (DARS) gene involved in mRNA translation. Clinical features of patients with DARS mutations include developmental delay, leg spasticity, cerebellar dysfunction, cognitive impairment and epilepsy. Most reported cases have been infantile-onset with severe neurological disability and neuroimaging abnormalities. To our knowledge, late- or adult-onset cases have never been reported in the literature. Here, we report for the first time, with video documentation and six-year clinical follow-up, an ethnic Malay patient with onset of spasticity and ataxia in late-adulthood, carrying a pathogenic DARS mutation discovered via whole-genome sequencing. His clinical and radiological findings were consistent with HBSL, but this diagnosis was not considered as, up until now, HBSL has only been reported with childhood/adolescent-onset. This case highlights that HBSL/DARS mutations should now be considered in the differential diagnosis of adult-onset spastic paraplegia and/or leukoencephalopathy.

A KMT2B Frameshift Variant Causing Focal Dystonia Restricted to the Oromandibular Region After Long-Term Follow-up

KMT2B-linked dystonia (DYT-KMT2B) is a childhood-onset dystonia syndrome typically beginning in the lower limbs and progressing caudocranially to affect the upper limbs with eventual prominent craniocervical involvement. Despite its recent recognition, it now appears to be one of the more common monogenic causes of dystonia syndromes. Here, we present an atypical case of DYT-KMT2B with oromandibular dystonia as the presenting feature, which remained restricted to this region three decades after symptom onset. This appears to be the first reported case of DYT-KMT2B from Southeast Asia and provides further supporting evidence for the pathogenic impact of the KMT2B c.6210_6213delTGAG variant.

Tree-in-Bud Opacities: Not only tuberculosis

We report a clinical case of mentally challenged young gentleman who was repeatedly hospitalized for respiratory symptoms. Contrast-enhanced CT (computed tomography) thorax revealed tree-in-bud (TIB) opacities. Provisional diagnosis of pulmonary tuberculosis was made and was referred to the respiratory team. However, after listening to patient's voice and reviewing the images on CT thorax, the diagnosis was confirmed as aspiration bronchiolitis.

Glucocerebrosidase (GBA) gene variants in a multi-ethnic Asian cohort with Parkinson's disease: mutational spectrum and clinical features

GBA variants are associated with increased risk and earlier onset of Parkinson's disease (PD), and more rapid disease progression especially with "severe" variants typified by p.L483P. GBA mutation screening studies from South-East Asia, with > 650 million inhabitants of diverse ancestries, are very limited. We investigated the spectrum of GBA variants, and associated clinico-demographic features, in a multi-ethnic PD cohort in Malaysia. Patients (n = 496) were recruited from seven centres, primarily of Chinese (45%), Malay (37%), and Indian (13%) ethnicities. All GBA coding exons were screened using a next-generation sequencing-based PD gene panel and verified with Sanger sequencing. We identified 14 heterozygous GBA alleles consisting of altogether 17 missense variants (8 classified as pathogenic or likely pathogenic for PD) in 25 (5.0%) patients, with a substantially higher yield among early (< 50 years) vs. late-onset patients across all three ethnicities (9.1-13.2% vs. 1.0-3.2%). The most common variant was p.L483P (including RecNciI, n = 11, 2.2%), detected in all three ethnicities. Three novel variants/recombinant alleles of uncertain significance were found; p.P71L, p.L411P, and p.L15S(;)S16G(;)I20V. The common European risk variants, p.E365K, p.T408M, and p.N409S, were not detected. A severe disease course was noted in the majority of GBA-variant carriers, across a range of detected variants. We report a potentially novel observation of spine posture abnormalities in GBA-variant carriers. This represents the largest study on GBA variation from South-East Asia, and highlights that these populations, especially those with EOPD, would be relevant for studies including clinical trials targeting GBA pathways.

Association study of MCCC1/LAMP3 and DGKQ variants with Parkinson's disease in patients of Malay ancestry

BACKGROUND

Genome-wide association studies (GWAS) have shown that variants in the 3-methylcrotonyl-CoA carboxylase (MCCC1)/lysosome-associated membrane protein 3 (LAMP3) loci (rs10513789, rs12637471, rs12493050) reduce the risk of Parkinson's disease (PD) in Caucasians, Chinese and Ashkenazi-Jews while the rs11248060 variant in the diacylglycerol kinase theta (DGKQ) gene increases the risk of PD in Caucasian and Han Chinese cohorts. However, their roles in Malays are unknown. Therefore, this study aims to investigate the association of these variants with the risk of PD in individuals of Malay ancestry.

METHODS

A total of 1114 subjects comprising of 536 PD patients and 578 healthy controls of Malay ancestry were recruited and genotyped using Taqman® allelic discrimination assays.

RESULTS

The G allele of rs10513789 (OR = 0.83, p = 0.001) and A allele of rs12637471 (OR = 0.79, p = 0.007) in the MCCC1/LAMP3 locus were associated with a protective effect against developing PD in the Malay population. A recessive model of penetrance showed a protective effect of the GG genotype for rs10513789 and the AA genotype for rs12637471. No association with PD was found with the other MCCC1/LAMP3 rs12493050 variant or with the DGKQ (rs11248060) variant. No significant associations were found between the four variants with the age at PD diagnosis.

CONCLUSION

MCCC1/LAMP3 variants rs10513789 and rs12637471 protect against PD in the Malay population.

Probiotics for Constipation in Parkinson Disease: A Randomized Placebo-Controlled Study

OBJECTIVE

To determine whether probiotics are effective for constipation, a common and often difficult-to-treat problem, in Parkinson disease (PD).

METHODS

In this double-blind, randomized, placebo-controlled, single-center trial, 280 patients with PD were screened, and 72 eligible patients were block-randomized (1:1) to receive either multistrain probiotics capsules (n = 34) or identical-appearing placebo (n = 38), for 4 weeks. The primary endpoint was the change in the average number of spontaneous bowel movements (SBM) per week during the last 2 weeks of intervention compared with the 2-week preintervention phase, recorded by daily stool diary. Secondary outcome measures included changes in stool consistency, constipation severity score, and quality of life related to constipation. Satisfaction with intervention received was assessed. Change in levels of fecal calprotectin, a marker of intestinal inflammation, was an exploratory outcome.

RESULTS

SBM increased by 1.0 ± 1.2 per week after treatment with probiotics and decreased by 0.3 ± 1.0 per week in the placebo group (mean difference 1.3, 95% confidence interval 0.8-1.8, p < 0.001). Significant improvements were also seen for secondary outcomes after correction for multiple comparisons, including stool consistency (p = 0.009) and quality of life related to constipation (p = 0.001). In the treatment group, 65.6% reported satisfaction with the intervention vs only 21.6% in the placebo group (p < 0.001). One patient (2.9%) in the treatment group withdrew due to a nonserious adverse event. Fecal calprotectin did not change significantly during the study.

CONCLUSIONS

Multistrain probiotics treatment was effective for constipation in PD. Further studies are needed to investigate the long-term efficacy and safety of probiotics in PD, as well as their mechanisms of action.

CLINICALTRIALSGOV IDENTIFIER

NCT03377322.

CLASSIFICATION OF EVIDENCE

This study provides Class I evidence that, for people with PD, multistrain probiotics significantly increased the average number of SBM per week.

Clinical Phenotype of LRRK2 R1441C in 2 Chinese Sisters

Pathogenic and risk variants in the LRRK2 gene are among the main genetic contributors to Parkinson's disease (PD) worldwide, and LRRK2-targeted therapies for patients with PARK-LRRK2are now entering clinical trials. However, in contrast to the LRRK2 G2019S mutation commonly found in Caucasians, North-African Arabs, and Ashkenazi Jews, relatively little is known about other causative LRRK2 mutations, and data on genotype-phenotype correlations are largely lacking. This report is from an ongoing multicentre study in which next-generation sequencing-based PD gene panel testing has so far been conducted on 499 PD patients of various ethnicities from Malaysia. We describe 2 sisters of Chinese ancestry with PD who carry the R1441C mutation in LRRK2 (which in Asians has been reported in only 2 Chinese patients previously), and highlight interesting clinical observations made over a decade of close follow-up. We further explored the feasibility of using a brief, expert-administered rating scale (the Clinical Impression of Severity Index; CISI-PD) to capture data on global disease severity in a large (n = 820) unselected cohort of PD patients, including severely disabled individuals typically excluded from research studies. All patients in this study were managed and evaluated by the same PD neurologist, and these data were used to make broad comparisons between the monogenic PD cases versus the overall "real world" PD cohort. This report contributes to the scarce literature on R1441C PARK-LRRK2, offering insights into natural history and epidemiological aspects, and provides support for the application of a simple and reliable clinical tool that can improve the inclusion of under-represented patient groups in PD research.

Identification of Risk Loci for Parkinson Disease in Asians and Comparison of Risk Between Asians and Europeans: A Genome-Wide Association Study

Importance

Large-scale genome-wide association studies in the European population have identified 90 risk variants associated with Parkinson disease (PD); however, there are limited studies in the largest population worldwide (ie, Asian).

Objectives

To identify novel genome-wide significant loci for PD in Asian individuals and to compare genetic risk between Asian and European cohorts.

Design Setting, and Participants

Genome-wide association data generated from PD cases and controls in an Asian population (ie, Singapore/Malaysia, Hong Kong, Taiwan, mainland China, and South Korea) were collected from January 1, 2016, to December 31, 2018, as part of an ongoing study. Results were combined with inverse variance meta-analysis, and replication of top loci in European and Japanese samples was performed. Discovery samples of 31 575 individuals passing quality control of 35 994 recruited were used, with a greater than 90% participation rate. A replication cohort of 1 926 361 European-ancestry and 3509 Japanese samples was analyzed. Parkinson disease was diagnosed using UK Parkinson's Disease Society Brain Bank Criteria.

Main Outcomes and Measures

Genotypes of common variants, association with disease status, and polygenic risk scores.

Results

Of 31 575 samples identified, 6724 PD cases (mean [SD] age, 64.3 [10] years; age at onset, 58.8 [10.6] years; 3472 [53.2%] men) and 24 851 controls (age, 59.4 [11.4] years; 11 030 [45.0%] men) were analyzed in the discovery study. Eleven genome-wide significant loci were identified; 2 of these loci were novel (SV2C and WBSCR17) and 9 were previously found in Europeans. Replication in European-ancestry and Japanese samples showed robust association for SV2C (rs246814; odds ratio, 1.16; 95% CI, 1.11-1.21; P = 1.17 × 10-10 in meta-analysis of discovery and replication samples) but showed potential genetic heterogeneity at WBSCR17 (rs9638616; I2=67.1%; P = 3.40 × 10-3 for hetereogeneity). Polygenic risk score models including variants at these 11 loci were associated with a significant improvement in area under the curve over the model based on 78 European loci alone (63.1% vs 60.2%; P = 6.81 × 10-12).

Conclusions and Relevance

This study identified 2 apparently novel gene loci and found 9 previously identified European loci to be associated with PD in this large, meta-genome-wide association study in a worldwide population of Asian individuals and reports similarities and differences in genetic risk factors between Asian and European individuals in the risk for PD. These findings may lead to improved stratification of Asian patients and controls based on polygenic risk scores. Our findings have potential academic and clinical importance for risk stratification and precision medicine in Asia.

LRRK2 N551K and R1398H variants are protective in Malays and Chinese in Malaysia: A case-control association study for Parkinson's disease

BACKGROUND

The LRRK2 gene is associated with Parkinson's disease (PD) as a number of mutations within the gene have been shown to be susceptibility factors. Studies on various global populations have determined that mutations such as G2019S, G2385R, and R1628P in LRRK2 increase the risk of developing PD while the N551K-R1398H haplotype is associated with conferring protection against developing PD. Here we report a study looking at the N551K and R1398H variants for the first time in the Malaysian population.

METHODS

Cases (523) which conformed to the United Kingdom PD Brain Bank Criteria for PD were recruited through trained neurologists and age- and ethnically matched controls (491) were individuals free of any neurological disorder. The N551K and R1398H mutations were genotyped using the Taqman SNP genotyping assay.

RESULTS

A significant protective association for N551K was found in those of Malay ancestry, with a protective trend seen for R1398H. A meta-analysis of Chinese individuals in this cohort with other published cohorts of Chinese ancestry indicated a significant protective role for N551K and R1398H.

CONCLUSION

This study reports that the N551K-R1398H haplotype is also relevant to the Malaysian population, with a significant protective effect found in those of Malay and Chinese ancestries.

Purposeless Groaning in Parkinson's Disease

Purposeless groaning has been reported in advanced progressive supranuclear palsy. We present a case of purposeless groaning occurring as a primary complaint in a patient with advanced Parkinson’s disease. Purposeless groaning is thought to be a manifestation of disinhibition and perseveration due to frontal-subcortical dysfunction. Proper recognition of this phenomenon will help clinicians to avoid unnecessary investigations and treatment (e.g., prescription of opioid medications).

A Patient with Beta-Propeller Protein-Associated Neurodegeneration: Treatment with Iron Chelation Therapy

We present a case of beta-propeller protein-associated neurodegeneration, a form of neurodegeneration with brain iron accumulation. The patient harbored a novel mutation in the WDR45 gene. A detailed video and description of her clinical condition are provided. Her movement disorder phenomenology was characterized primarily by limb stereotypies and gait dyspraxia. The patient's disability was advanced by the time iron-chelating therapy with deferiprone was initiated, and no clinical response in terms of cognitive function, behavior, speech, or movements were observed after one year of treatment.

Fiber-integrated 780 nm source for visible parametric generation

We report the development of a fully fiber-integrated pulsed master oscillator power fibre amplifier (MOPFA) source at 780 nm, producing 3.5 W of average power with 410 ps pulses at a repetition rate of 50 MHz. The source consists of an intensity modulated 1560 nm laser diode amplified in an erbium fiber amplifier chain, followed by a fiber coupled periodically poled lithium niobate crystal module for frequency doubling. The source is then used for generating visible light through four-wave mixing in a length of highly nonlinear photonic crystal fiber: 105 mW at 668 nm and 95 mW at 662 nm are obtained, with pump to anti-Stokes conversion slope efficiencies exceeding 6% in both cases.

Effect of internal recycle rate on the high-strength nitrogen wastewater treatment in the combined UBF/MBR system

An anaerobic/aerobic system combining an anaerobic upflow-sludge bed filter (UBF) and an aerobic membrane bioreactor (MBR) was operated to enhance organic and nitrogen removal efficiency. The internal recycle rate, which is one of the most important operation factors that affects overall removal efficiency, was varied from 100% to 300% of the influent flow. Under these conditions, the overall removal efficiencies of organic and nitrogen and characteristics of membrane fouling in the combined system treating the synthetic wastewater including high concentration of organics and nutrients were studied. As a result, nitrogen removal efficiency was increased to 67% when the internal recycle rate was 300% of influent flow rate. As the internal recycle ratio increased from 100% to 200%, protein content decreased by 17% and carbohydrate content increased by 12%. However, there was no remarkable difference in total extracellular polymeric substances (EPS) content. At the high recycle rate of 300%, the surface charge of sludge was decreased while hydrophobicity (specific ultraviolet absorbance, SUVA) was increased. The differences in SUVA and surface charge were 11% and 1%, respectively. It is concluded that SUVA and EPS composition were important parameters affecting membrane fouling in the combined system.

Experience with portfolio-based learning in family medicine for master of medicine degree

BACKGROUND

The Private Practitioners Stream (PPS) of the Family Medicine Traineeship Programme for the Master of Medicine (Family Medicine) (MMed (FM)) was started in 1995. The portfolio-based learning approach was used as the staple learning method in the tutorial system. Due to the autonomy given to Family Medicine trainees in choosing the topics for the portfolio-based presentations, the completeness of coverage of the Family Medicine training syllabus is a research question.

AIM

To study if portfolio-based presentations in a tutorial system covered the broad based Family Medicine training syllabus.

METHOD

Data in the one-page portfolio-based records developed were used to categorise the presentations according to the topics in the Family Medicine Modular Course.

RESULTS

In the three-year period since the introduction of the PPS, 83 tutorials were conducted in which 87 portfolio-based presentations were made. Thirteen (15%) were in the Whole Person Medicine category, 70 (80%) in the Disease Management category and 4 (5%) in the Practice Management category.

CONCLUSION

The portfolio-based learning is recognised as useful in continuing medical education because of the autonomy it gives to the adult learner. In our three years' experience, the one-page portfolio-based record developed was effective as the staple learning tool to cover the broad range of topics required in the defined syllabus of training and to meet the focus of the MMed(FM) examination.

The use of 3-methoxymethyl-16 beta, 17 beta-epiestriol-O-cyclic sulfone as the precursor in the synthesis of F-18 16 alpha-fluoroestradiol

We have prepared 3-methoxymethyl-16 beta, 17 beta-epiestriol-O-cyclic sulfone (1c) and used it as a substrate for the production of F-18 16 alpha-fluoroestradiol, via nucleophilic fluorination with fluoride ion. The compound is straightforward to make from the commercially available epiestriol and is a stable crystalline compound that can be stored for at least a year at room temperature. Reaction with fluorine-18 fluoride provides excellent yields; typically > 90% incorporation of the fluoride is achieved. Partial purification of the labeled product may be accomplished at this stage. Hydrolysis of the methoxymethyl protecting group and ring-opened sulfate occurs rapidly in ethanolic acid solution. In the presence of water the hydrolysis requires more vigorous conditions and additional time but still proceeds to completion. Labeled fluoroestradiol is isolated at the end of a 1-2 h synthesis, depending on the hydrolysis method of 30-45% chemical (decay corrected) yield with respect to fluoride, with a specific activity > 1 Ci per micromole.

An efficient radiosynthesis of [18F]fluoromisonidazole

An efficient preparation of the hypoxic cell tracer [18F]3-fluoro-1-(2'-nitro-1'-imidazolyl)-2-propanol ([18F]fluoromisonidazole) is reported. This radiopharmaceutical is of interest to probe hypoxic tissue in infarcts and tumors. One-step radiolabeling and rapid protection group removal provided 55-80% yield in 50 min. The process is similar to common fluorine labeling procedures, simplifying the procedure for most laboratories, and offers an improvement over more difficult previous methods. The labeling precursor was prepared in five steps from readily available materials in a straightforward reaction scheme.

Synthesis and in vitro receptor binding studies of fluorotamoxifen analogues

We describe the synthesis of new fluorotamoxifen analogues with the fluorine atom positioned on the end of the aliphatic chain of tamoxifen. The binding of fluorotamoxifens to cytosol estrogen receptors of rat uteri was determined with [3H]estradiol (5 nM). The fluorotamoxifens had similar or superior binding affinities compared with tamoxifen. The IC50 value was as follows: tamoxifen, 5 x 10(-7) M; fluorotamoxifen (VII), 5 x 10(-7) M; N,N-diethylfluorotamoxifen (IV)-cis, 1 x 10(-6) M, and trans, 2 x 10(-7) M; and (cis) fluoromethyl-N,N-diethyltamoxifen (VI) 1 x 10(-7) M. Therefore, the fluorinated tamoxifens have potential use in imaging estrogen receptors by PET.

Relative potency of lambdacyhalothrin and cypermethrin applied as thermal fogs for the control of houseflies (Musca domestica) and mosquitos (Aedes aegypti)

Two highly active synthetic pyrethroid insecticides, lambdacyhalothrin and cypermethrin, were evaluated as thermal fogs against houseflies (Musca domestica Linnaeus) and mosquitos (Aedes aegypti Linnaeus). Lambdacyhalothrin (OMS 3021) showed an average of 2.5 times more knockdown activity and over 5 times more adulticidal activity than cypermethrin against Musca domestica and Aedes aegypti. These results demonstrate that lambdacyhalothrin is highly effective at very low rates as a thermal fog against Ae. aegypti and M. domestica. Commercially available formulations of 2.5% and 5% lambdacyhalothrin can be diluted either with water for ULV cold aerosol space-spraying or with diesel/kerosene for thermal fogging at recommended application rates of 0.5-1 g ai/ha for mosquito control and 2 g ai/ha for housefly control. Due to the very low rates of application, formulated products of lambdacyhalothrin are unlikely to present any acute hazards in normal use. The low dosages required to bring about rapid control of houseflies and mosquitos make this new pyrethroid insecticide particularly cost-effective. Coupled with its good residual activity (Jutsum et al, 1984), lambdacyhalothrin can be adopted as a powerful tool in integrated pest management program for the control of medically important pests and vectors.