Management of fascial space infections using ultrasonography as a surgical guide for drainage - A case series

Fascial space infections are common emergencies presented to a maxillofacial surgeon. Space infection requires early diagnosis and prompt management. When left untreated, space infection spreads and involves not just one space, but also its adjacent spaces. Abscess in the head and neck region are treated by surgical incision and drainage, along with antibiotics and removal of the causative factor. The surgical incision and drainage of an abscess, if carried out based on physical examination may result in, excessive pain, tissue trauma, unnecessary extensive incisions, excess time and failure to locate and evacuate the abscess fluid. To avoid all such complications, ultrasonography is not only an invaluable diagnostic tool but also aids in ultrasonography guided drainage of fascial space infections.

A note on the insecticide susceptibility status of secondary malaria vector An. annularis in Jharkhand state of India

BACKGROUND & OBJECTIVES

An. annularis van der Wulp (1884) is the secondary malaria vector of importance in India. In Jharkhand state it is present in almost all the districts abundantly and transmits malaria. The development of resistance to Dichlorodipheny ltrichloroethane (DDT) in An. annularis was reported from various parts of India. The main objective of this study was to generate information on insecticide susceptibility status of An. annularis to DDT, malathion, deltamethrin and permethrin in different districts of Jharkhand state. Methods; Adult An. annularis female mosquitoes were collected form villages of six tribal districts Simdega (Kurdeg and Simdega CHC), Khunti (Murhu and Khunti CHCs), Gumla (Bharno and Gumla CHCs), West Singhbhum (Chaibasa and Bada Jamda CHCs), Godda (Poraiyahat and Sunderpahari (CHCs) and Sahibganj (Borio and Rajmahal CHCs). Insecticide susceptibility status was determined by using WHO tube test method against prescribed discriminatory dosages of insecticides, DDT - 4.0%, malathion - 5.0%, deltamethrin - 0.05% and permethrin - 0.75%.

RESULTS

An. annularis was reported resistant to DDT in six districts, possible resistant to malathion in districts Gumla, Khuntiand Sahibganj and susceptible to deltamehrin (98% to100% mortality) and permethrin (100% mortality).

INTERPRETATION & CONCLUSION

An. annularis, the secondary vector species is associated with the transmission of malaria reported resistant to DDT and susceptible to pyrerthroids deltamethrin and permethrin. In view of large-scale distribution of long-lasting insecticidal nets (LLINs) in all the districts, the response to synthetic pyrethroid needs to be periodically monitored to assess the effectiveness.

Factors determining loss of reduction in paediatric supracondylar humerus fractures treated by closed reduction and percutaneous pinning

Closed reduction and percutaneous pinning is the preferred surgical intervention for paediatric supracondylar humerus fractures (SCHF). Loss of reduction (LOR) is one of the infrequent complications associated with percutaneous pinning. We aim to analyse the various factors that could lead to LOR. We retrospectively reviewed records of all children with Gartland's type III and IV SCHF who were operated at our institution between 2014 and 2016. A defined set of radiologic indices were measured on postoperative and follow-up radiographs. Correlation between LOR (as defined by Skaggs) and radiologic indices, was calculated. In total 187 children who satisfied the inclusion criteria were included in the study. Major LOR was present in 8 patients (4.28%), mild LOR was seen in 21 patients (11.22%), and there was no LOR in 158 patients (84.49%). A pin-spread fracture width ratio of 0.37 had maximum sensitivity and specificity for predicting LOR. The convergent pin configuration had the highest rate of LOR of 15%, whereas it was about 3% in the crossed pin and lateral divergent pinning group. The incidence of iatrogenic ulnar nerve injury in our series was 4.76%, and all were in the cross pinning group. Pin-spread fracture width ratio is the most crucial factor determining LOR, and a ratio of less than 0.37 has a significantly higher rate of LOR. As the incidence of LOR is not significantly different between the lateral-only and crossed pin groups, a medial pin should be used judiciously to avert the risk of ulnar nerve injury. Level of evidence: Level IV.

Insecticide susceptibility status of malaria vectors, Anopheles culicifacies, Anopheles fluviatilis and Anopheles minimus in the tribal districts of Jharkhand state of India

BACKGROUND AND OBJECTIVES

Insecticide resistance in malaria vectors has been a major challenge to vector control programs and updated information to the commonly used insecticides is essential for planning appropriate vector control measures. Anopheles culicifacies and An. fluviatilis are the two main vectors prevalent in Jharkhand state of India and role of An. minimus is contemplated in the transmission of malaria in this state. All the districts in the state are predominantly inhabited by the tribal population and are endemic for malaria. A study was undertaken in 12 districts of Jharkhand state to determine the insecticide susceptibility status of the 3 prevalent primary vector species, An. culicifacies, An. fluviatilis, and An. minimus.

METHODS

Wild-caught adult female An. culicifacies, An. fluviatilis, and An. minimus, mosquitoes were collected from stratified ecotypes from different localities of 12 tribal districts of Jharkhand state during 2018 and 2019. Susceptibility tube tests were conducted following the WHO method using test kits. Mosquitoes were exposed to WHO impregnated papers with the prescribed discriminatory dosages of DDT - 4%, malathion - 5%, deltamethrin - 0.05%, permethrin - 0.75%, cyfluthrin - 0.15% and lambda cyhalothrin - 0.05%.

RESULTS

Results indicated that An. culicifacies has developed multiple insecticide resistance in all the 12 districts of Jharkhand state. An. fluviatilis was reported resistant for the first time to DDT in all the districts but was susceptible to malathion, deltamethrin, and permethrin whereas in one district it showed possible resistance to malathion. An. minimus was studied in Noamundi CHC of West Singhbhum district, showed possible resistance against DDT but was susceptible to malathion, deltamethrin, and permethrin.

INTERPRETATION & CONCLUSION

The development of multiple insecticide resistance in An. culicifacies including to pyrethroids, has been a concern for malaria control programmes for effective vector management but a report of resistance to DDT for the first time in An. fluviatlis in all the districts in the state is alarming, An. minimus was found in possible resistance category to DDT in one district and both the species were reported susceptible to malathion, deltamethrin, and permethrin. The result of the present study indicates a need for regular monitoring to assess the insecticide susceptibility to formulate effective vector control measures and resistance management.

Sleep profile and Polysomnography in patients with drug-resistant temporal lobe epilepsy (TLE) due to hippocampal sclerosis (HS) and the effect of epilepsy surgery on sleep-a prospective cohort study

OBJECTIVES

We analyzed changes in sleep profile and architecture of patients with drug-resistant TLE-HS using three validated sleep questionnaires- Epworth Sleepiness Scale (ESS), Pittsburgh Sleep Quality Index (PSQI), NIMHANS Comprehensive Sleep Disorders, and polysomnography (PSG). We studied the effect of epilepsy surgery in a subset of patients.

METHODS

In this prospective observational cohort study, sleep profile of 40 patients with drug-resistant TLE-HS was compared to 40 healthy matched controls. Sleep architecture of 22 patients was studied by overnight PSG and compared to 22 matched controls. Sleep profile was reassessed in 20 patients after a minimum period of three months after epilepsy surgery.

RESULTS

The mean PSQI was higher among patients compared to controls(P=0.0004) while mean ESS showed no difference. NCSDQ showed fewer patients feeling refreshed after a night's sleep compared to controls (p=0.006). PSG revealed a higher time in bed (p=0.0001), longer total sleep time (p=0.006) and more time spent in NREM stage 1 (p=0.001) and stage 2 (p=0.005) while spending less time in stage 3 (p=0.039) among TLE patients. Sleep efficiency was worse in patients on ≥3 ASMs compared to those on 2 ASMs (p-0.044). There was no change in mean ESS (p=0.48) or PSQI (p=0.105) after surgery.

CONCLUSIONS

Patients with drug-resistant TLE-HS have an altered sleep profile and architecture. Patients on ≥3 ASMs have a lower sleep efficiency. Reassessment at short intervals after epilepsy surgery did not reveal significant changes in sleep profile.

Motor Imagery Hand Movement Direction Decoding Using Brain Computer Interface to Aid Stroke Recovery and Rehabilitation

Motor Imagery (MI)-based Brain Computer Interface (BCI) system is a potential technology for active neurorehabilitation of stroke patients by complementing the conventional passive rehabilitation methods. Research to date mainly focused on classifying left vs. right hand/foot MI of stroke patients. Though a very few studies have reported decoding imagined hand movement directions using electroencephalogram (EEG)-based BCI, the experiments were conducted on healthy subjects. Our work analyzes MI-based brain cortical activity from EEG signals and decodes the imagined hand movement directions in stroke patients. The decoded direction (left vs. right) of hand movement imagination is used to provide control commands to a motorized arm support on which patient's affected (paralyzed) arm is placed. This enables the patient to move his/her stroke-affected hand towards the intended (imagined) direction that aids neuroplasticity in the brain. The synchronization measure called Phase Locking Value (PLV), extracted from EEG, is the neuronal signature used to decode the directional movement of the MI task. Event-related desynchronization/synchronization (ERD/ERS) analysis on Mu and Beta frequency bands of EEG is done to select the time bin corresponding to the MI task. The dissimilarities between the two directions of MI tasks are identified by selecting the most significant channel pairs that provided maximum difference in PLV features. The training protocol has an initial calibration session followed by a feedback session with 50 trials of MI task in each session. The feedback session extracts PLV features corresponding to most significant channel pairs which are identified in the calibration session and is used to predict the direction of MI task in left/right direction. An average MI direction classification accuracy of 74.44% is obtained in performing the training protocol and 68.63% from the prediction protocol during feedback session on 16 stroke patients.

EEG Observations in Probable Sporadic CJD

INTRODUCTION

Sporadic Creutzfeldt Jakob Disease, the most common reported prion disease, is a fatal neurodegenerative disease caused by the misfolding of protein PrP^C to PrP^SC. EEG is the first in vivo test to support the clinical diagnosis of sporadic CJD (sCJD). This study is carried out to describe the comprehensive electroencephalography changes in a cohort of patients with probable sCJD from south India.

METHODOLOGY

This retrospective observational study is conducted by reviewing case records from 2013-2020. Demographic, clinical, imaging details were noted. Electroencephalogram (EEG) recordings were retrieved and reviewed independently by two qualified epileptologists and the findings were visually analyzed and correlated with clinical and imaging abnormalities.

RESULTS

Fifty patients with probable sCJD with the availability of artefact-free EEG were included in the study. The mean age was 59.76 ± 8.17 years and M: F was 31:19. Magnetic resonance imaging (MRI) brain showed abnormality defining CJD in 48/50, i.e., 96%patients. EEG showed specific and or nonspecific abnormalities in 88%. The specific abnormalities, i.e., periodic sharp wave complexes (PSWC), were noted 66%. PSWC were mostly asymmetric (90%) and more frequently seen in the right hemisphere (57.6%). Amplitude maximum in the occipital region was noted in 42.4% and in frontal region in 36.4%. The sensitivity of EEG specific abnormalities to diagnose probable sCJD according to CDC 2018 criteria with positive MRI findings was 68.75%.

CONCLUSION

This study showed that EEG is a relatively inexpensive and sensitive tool and assists in the diagnosis of sCJD. However, it can be normal or show nonspecific abnormalities in the early stages of the disease.

Small-scale (Phase II) evaluation of the efficacy and residual activity of SumiShield® 50 WG (clothianidin 50%, w/w) for indoor residual spraying in comparison to deltamethrin, bendiocarb and pirimiphos-methyl for malaria vector control in Karnataka state, India

Background & objectives

There is an urgent need of introducing new insecticide molecules with novel modes of action to counter the ever growing insecticide-resistance in mosquito vectors. In the present study, a new insecticide molecule, SumiShield 50 WG (clothianidin 50%, w/w) was investigated for its efficacy as an indoor residual spray along with its residual action in comparison to deltamethrin, pirimiphos-methyl and bendiocarb.

Methods

The study area included three villages in Almatti Dam catchment area in Bagalkot district, Karnataka, India. Spraying was done using Hudson sprayers with the following dosages-Clothianidin, 300 mg AI/m²; deltamethrin, 25 mg AI/m²; bendiocarb, 400 mg AI/m²; and pirimiphos-methyl, 1 g AI/m². Cone bioassays were conducted on cement and mud plastered surfaces at fortnightly intervals to assess the bioefficacy and residual activity. Mosquito densities in the sprayed houses were recorded at regular intervals for assessment of the insecticidal efficacy. Filter paper samples collected from the sprayed houses were analyzed for insecticide content sprayed on different wall surfaces at the Walloon Agricultural Research Institute, Gembloux, Belgium.

Results

Chemical content analysis of filter paper samples revealed that the applied to target ratios were in the acceptable range (1 + 0.5) for all the treatment types. Duration of persistence of effectiveness of bendiocarb (≥80% mortality in cone bioassays) was 19 to 21 wk on cement plastered surfaces and 15 to 19 wk on mud plastered surfaces. Duration of persistence of effectiveness of deltamethrin was 17 to 21 wk on both mud and cement plastered surfaces and that of pirimiphos-methyl was 15 to 19 wk. For SumiShield, it was 17 to 25 wk on both types of surfaces, indicating slow action of SumiShield. The densities of Anopheles culicifacies were lower in bendiocarb sprayed houses throughout the observation period, followed by pirimiphos methyl, deltamethrin and clothianidin sprayed houses. In case of other mosquitoes also, similar trend was observed.

Interpretation & conclusion

Considering the persistence of effectiveness of SumiShield on sprayed surfaces, effectiveness in reducing the density of mosquitoes, operational feasibility, safety and community acceptance, the formulation of clothianidin is a better option for IRS for the control of insecticide-resistant mosquito vectors.

Burden of asymptomatic malaria among a tribal population in a forested village of central India: a hidden challenge for malaria control in India

Objective

Chhattisgarh in India is a malaria-endemic state with seven southern districts that contributes approximately 50–60% of the reported malaria cases in the state every year. The problem is further complicated due to asymptomatic malaria cases which are largely responsible for persistent transmission. This study was undertaken in one of the forested villages of the Keshkal subdistrict in Kondagaon district to ascertain the proportion of the population harbouring subclinical malarial infections.

Study design

Community-based cross-sectional study.

Methods

Mass blood surveys were undertaken of the entire population of the village in the post-monsoon seasons of 2013 and 2014. Fingerprick blood smears were prepared from individuals of all ages to detect malaria infections in their blood. Individuals with fever at the time of the survey were tested with rapid diagnostic tests, and parasitaemia in thick blood smears was confirmed by microscopy. Malaria-positive cases were treated with anti-malarials in accordance with the national drug policy.

Results

Peripheral blood smears of 134 and 159 individuals, including children, were screened for malaria infection in 2013 and 2014, respectively. Overall, the malaria slide positivity rates were 27.6% and 27.7% in 2013 and 2014, respectively, and the prevalence rates of asymptomatic malaria were 20% and 22.8%. This study showed that, for two consecutive years, the prevalence of asymptomatic malaria infection was significantly higher among children aged ≤14 years (34.4% and 34.1% for 2013 and 2014, respectively) compared with adults (15.2% and 18.2% for 2013 and 2014, respectively; P = 0.023 and 0.04, respectively).

Conclusion

The number of asymptomatic malaria cases, especially Plasmodium falciparum, is significant, reinforcing the underlying challenge facing the malaria elimination programme in India.

•

The study was carried out in a difficult-to-reach forested village with minimal access to healthcare facilities.

•

There exists a large proportion of asymptomatic cases in the community.

•

Children aged under 14 years comprised higher number of asymptomatic cases than adults.

•

This underlines one of the potential challenges of public health in malaria control and elimination programs.

A comparison of apical sealing ability between GuttaFlow and AH plus: An in vitro study

Aims:

The present study aimed to compare apical sealing ability between GuttaFlow and AH Plus.

Materials and Method:

Eighty extracted human maxillary anterior teeth with fully formed apex and straight root were collected for this study. The root canals were cleaned and shaped using a standard step back preparation to size 60# master apical file at the established working length and divided into four groups: Group 1, GuttaFlow sealer with gutta-percha; Group 2, AH Plus sealer with gutta-percha; Group 3, positive control group (Teeth were instrumented and left without obturation); Group 4, negative control group (Teeth were totally coated with nail varnish) Dye leakage was carried out. Statistical analysis was done using the Statistical Package for the Social Sciences software and Student's unpaired t-test.

Results:

The GuttaFlow group had a mean leakage of 1.38 mm whereas AH Plus had a mean of 1.425 mm. The standard deviation of GuttaFlow and AH Plus were 0.3861 and 0.3226, respectively. Student's unpaired t-test disclosed no significant difference (P < 0.05) between the groups.

Conclusion:

None of the sealers used in the study could completely seal the apical foramen to have a fluid-tight seal. GuttaFlow and AH Plus showed no statistically significant difference in microleakage; the better result was shown by GuttaFlow.

Reduced small world brain connectivity in probands with a family history of epilepsy

BACKGROUND AND PURPOSE

The role of inheritance in ascertaining susceptibility to epilepsy is well established, although the pathogenetic mechanisms are still not very clear. Interviewing for a positive family history is a popular epidemiological tool in the understanding of this susceptibility. Our aim was to visualize and localize network abnormalities that could be associated with a positive family history in a group of patients with hot water epilepsy (HWE) using resting-state functional magnetic resonance imaging (rsfMRI).

METHODS

Graph theory analysis of rsfMRI (clustering coefficient γ; path length λ; small worldness σ) in probands with a positive family history of epilepsy (FHE+, 25) were compared with probands without FHE (FHE-, 33). Whether a closer biological relationship was associated with a higher likelihood of network abnormalities was also ascertained.

RESULTS

A positive family history of epilepsy had decreased γ, increased λ and decreased σ in bilateral temporofrontal regions compared to FHE- (false discovery rate corrected P ≤ 0.0062). These changes were more pronounced in probands having first degree relatives and siblings with epilepsy. Probands with multiple types of epilepsy in the family showed decreased σ in comparison to only HWE in the family.

CONCLUSION

Graph theory analysis of the rsfMRI can be used to understand the neurobiology of diseases like genetic susceptibility in HWE. Reduced small worldness, proportional to the degree of relationship, is consistent with the current understanding that disease severity is higher in closer biological relations.

University of Pennsylvania Smell Identification Test Abnormalities in Parkinson's Disease

BACKGROUND

Olfactory dysfunction is a predominant non - motor symptom in patients with Parkinson's disease. Indian studies on olfactory loss using standardized kits are lacking.

OBJECTIVE

1) To assess the olfactory impairment in patients with Parkinson's disease 2) To verify the applicability of UPSIT to Indian subjects 3) To assess the correlation between olfactory dysfunction and duration, stage and severity of the illness.

MATERIALS AND METHODS

Patients with Parkinson's disease attending Neurology outpatient and inpatient departments were taken for the study. The details of demographic data and illness were collected. Patients with other risk factors for hyposmia were excluded from the study. Detailed neurological examination and smell test were done using University of Pennsylvania Smell Identification Test (UPSIT) kit. 40 healthy individuals without any pre-morbid illness or risk factors for hyposmia were studied for the applicability of the British version of UPSIT to the Indian population, 20 of whom were age and sex matched with the Parkinson's disease patients. Statistical analysis was done using Wilcoxon matched-pair signed-ranks test (WSRT)) and Pearson correlation test.

RESULTS

Parkinson's disease patients had a mean age 58.2 years and a mean duration of illness of 5.5 years. Parkinson's disease patients had a low score on UPSIT compared to controls which was statistically significant (p 0.000) and the loss spanned a variety of odorants in UPSIT. There was no correlation with the age, staging or duration of the illness.

CONCLUSIONS

Olfactory loss is a significant non motor symptom in Parkinson's disease patients and is probably not related to the disease duration, stage or severity of motor symptoms.

Seizure Frequency Can Alter Brain Connectivity: Evidence from Resting-State fMRI

BACKGROUND AND PURPOSE

The frequency of seizures is an important factor that can alter functional brain connectivity. Analysis of this factor in patients with epilepsy is complex because of disease- and medication-induced confounders. Because patients with hot-water epilepsy generally are not on long-term drug therapy, we used seed-based connectivity analysis in these patients to assess connectivity changes associated with seizure frequency without confounding from antiepileptic drugs.

MATERIALS AND METHODS

Resting-state fMRI data from 36 patients with hot-water epilepsy (18 with frequent seizures [>2 per month] and 18 with infrequent seizures [≤2 per month]) and 18 healthy age- and sex-matched controls were analyzed for seed-to-voxel connectivity by using 106 seeds. Voxel wise paired t-test analysis (P < .005, corrected for false-discovery rate) was used to identify significant intergroup differences between these groups.

RESULTS

Connectivity analysis revealed significant differences between the 2 groups (P < .001). Patients in the frequent-seizure group had increased connectivity within the medial temporal structures and widespread areas of poor connectivity, even involving the default mode network, in comparison with those in the infrequent-seizure group. Patients in the infrequent-seizure group had focal abnormalities with increased default mode network connectivity and decreased left entorhinal cortex connectivity.

CONCLUSIONS

The results of this study suggest that seizure frequency can alter functional brain connectivity, which can be visualized by using resting-state fMRI. Imaging features such as diffuse network abnormalities, involvement of the default mode network, and recruitment of medial temporal lobe structures were seen only in patients with frequent seizures. Future studies in more common epilepsy groups, however, will be required to further establish this finding.

Chlorfenapyr: irritant effect compared to other insecticides and its intrinsic toxicity in multiple-insecticide-susceptible and -resistant Anopheles stephensi (Diptera: Culicidae)

BACKGROUND & OBJECTIVES

For effective management of vector resistance there is a need for new insecticide molecules with novel modes of action. For desired toxic effect of an insecticide, apart from other behavioural aspects, toxicity and chemical nature of the molecule are important that may cause irritability in the mosquito to the insecticide affecting the uptake. In this study, a pyrrole class insecticide, chlorfenapyr (a late acting insecticide) was tested for its irritability against multiple-insecticide-susceptible and -resistant strains of Anopheles stephensi Liston 1901 (Diptera: Culicidae).

METHODS

Studies were conducted to assess the irritability due to chlorfenapyr, DDT, malathion, deltamethrin and permethrin and intrinsic toxicity of chlorfenapyr in multiple-insecticide-susceptible and -resistant laboratory strains of An. stephensi following standard WHO methods.

RESULTS

Chlorfenapyr molecule has shown least irritant effect against susceptible and resistant strains among all the insecticides tested allowing more landing time to the vector species on the impregnated surfaces to pick-up lethal dose.

CONCLUSION

Chlorfenapyr could be an ideal insecticide for management of multiple-insecticide-resistance including pyrethroids.

Identification and classification of detoxification enzymes from Culex quinquefasciatus (Diptera: Culicidae)

Molecular characterization of the insecticide resistance has become a hot research topic ever since the first disease transmitting arthropod (Anopheles gambiae) genome sequence has unveiled in 2002. A recent publication of the Culex quinquefasciatus genome sequence has opened up new opportunities for molecular and comparative genomic analysis of multiple mosquito genomes to characterize the insecticide resistance. Here, we utilized a whole genome sequence of Cx. quinquefasciatus to identify putatively active members of the detoxification supergene families, namely cytochrome P450s (P450s), glutathione-S-transferases (GSTs), and choline/carboxylesterases (CCEs). The Culex genome analysis revealed 166 P450s, 40 GSTs, and 62 CCEs. Further, the comparative genomic analysis shows that these numbers are considerably higher than the other dipteran mosquitoes. These observed speciesspecific expansions of the detoxification super gene family members endorse the popular understanding of the involvement of these gene families in protecting the organism against multitudinous classes of toxic substances during its complex (aquatic and terrestrial) life cycle. Thus, the generated data set may provide an initial point to start with to characterize the insecticide resistance at a molecular level which could then lead the development of an easy to use molecular marker to monitor the incipient insecticide resistance in field environs.

Mosquito larvicidal properties of aqueous and acetone extracts of Trianthema portulacastrum Linn. (family: Aizoaceae) against vector species of mosquitoes

Crude aqueous and acetone extracts of leaf of Trianthema portulacastrum was evaluated for its mosquito larvicidal properties against the larvae of four vector species of mosquito under laboratory conditions. These extracts showed good larvicidal properties, 100% mortality in the third instar larvae was observed in the larval bioassay test with Anopheles culicifacies, Anopheles stephensi, Culex quinquefasciatus and Aedes aegypti at a concentration of 1.0, 0.75, 0.75 and 1.0% respectively. The LD50 values estimated for aqueous extract against the larvae of An. culicifacies, An. stephensi, Cx. quinquefasciatus and Ae. aegypti were 0.17, 0.15, 0.18 and 0.17% and LD90 values were 0.57, 0.58, 0.76, and 0.75% respectively. The LD50 values estimated for acetone extract against the larvae of An. culicifacies, An. stephensi, Cx. quinquefasciatus and Ae. aegypti were 0.09, 0.10, 0.09 and 0.12 % and LD90 values were 0.28, 0.25, 0.26 and 0.26% respectively. It is observed that the acetone extract is more effective as compared to aqueous extract. Trianthema portulacastrum can be considered as a probable source of photochemical used for the development of larvicide against disease vectors.

In silico characterization and comparative genomic analysis of the Culex quinquefasciatus glutathione S-transferase (GST) supergene family

The glutathione S-transferases (GSTs) are phase II class of detoxification enzymes that are involved both directly and indirectly in insecticide resistance mechanisms. The Culex quinquefasciatus GST superfamily was analyzed by utilizing the public domain Culex genome sequence. In total, 35 cytosolic (seven classes) and 5 microsomal putatively active GSTs were retrieved, classified, and annotated. The study revealed the presence of three unclassified GSTs. Of 35 cytosolic GSTs, 65% contributed by insect specific Delta-Epsilon classes. Gene cluster analysis revealed that most of the genes of Delta, Epsilon, and Theta classes were organized into gene clusters. The gene organization analysis revealed the dominance of phase "0" introns in the Culex GST family. The studies on intron loss and gain events revealed that the Delta GSTs have experienced a higher number of loss and gains during their evolution. A positive correlation was observed between the phylogenetic relationship of members of the GST superfamily and their corresponding exon-intron organization. In addition, the genes within the gene clusters revealed the monophyletic phylogenetic relationship implying the importance of gene duplication events in the gene families' evolution. Finally, the comparative genomic analysis has shown a complex evolutionary scenario associated with the GST supergene family evolution in insects.

Field evaluation of lambda-cyhalothrin (ICON 10 CS) indoor residual spraying against Anopheles culicifacies in India

BACKGROUND & OBJECTIVES

Field trials of lambda-cyhalothrin 10 CS (ICON 10 CS) in indoor residual spraying (IRS) with 25 mg a.i./m2 against Anopheles culicifacies was undertaken vs malathion IRS (25% WP-2 g a.i./m2) in Tumkur district, Karnataka; vs deltamethrin IRS (2.5% WP-20 mg a.i./m2) in Dharmapuri district; and vs lambda-cyhalothrin (10 WP-25 mg a.i./m2) in Ramanathapuram district, Tamil Nadu, India.

METHODS

Spray operations in the experimental villages were done by the National Institute of Malaria Research (NIMR) and in the control villages by the respective State Health Department staff. Persistence of efficacy of insecticide sprayed in villages was assessed by contact bioassays against vector mosquitoes. Entomological indicators such as per structure density, parity rates of vector mosquitoes and sporozoite rates were measured in all the three study areas using standard procedures. Mass blood surveys and active fever case detections were carried out in experimental and control villages to study the impact of IRS on malaria transmission.

RESULTS

Persistence of effectiveness of ICON 10 CS was observed up to 2-3 months in all the three study areas. ICON 10 CS was found effective at par with or better than the insecticides used in the national programme in reducing the mosquito densities and in interrupting malaria transmission in the study villages. Vector density, parity rates and malaria cases considerably reduced in the ICON 10 CS-sprayed villages.

CONCLUSION

Field trials at three sites have established that ICON 10 CS formulation was relatively more effective than malathion 25% WP, deltamethrin 2.5% WP and lambda-cyhalothrin 10% WP in some evaluation parameters like indoor resting mosquitoes, parity rates in vector mosquitoes and persistence of effectiveness. It can be used for IRS for malaria vector control with two rounds of spray at an interval of 3 months for curtailing the malaria transmission and an additional round is recommended in perennial malaria transmission areas.

Wash-resistance and field evaluation of alphacypermethrin treated long-lasting insecticidal net (Interceptor) against malaria vectors Anopheles culicifacies and Anopheles fluviatilis in a tribal area of Orissa, India

A field trial was conducted on the efficacy of Interceptor nets-a long-lasting insecticidal net (LLN) factory treated with alphacypermethrin 0.667% (w/w) corresponding to 200mg/m(2), against malaria vectors Anopheles culicifacies and Anopheles fluviatilis in one of the highly endemic areas of Orissa. The study area comprised 19 villages which were randomized into three clusters and designated as Interceptor net cluster, untreated net cluster, and no net cluster. Baseline studies showed that both the vector species An. culicifacies and An. fluviatilis were 100% susceptible to alphacypermethrin. Results of wash-resistance and bio-efficacy of Interceptor nets showed 100% mortality in An. culicifacies and An. fluviatilis even after 20 washings. Bioassays on the Interceptor nets while in use in the field conditions showed a knockdown effect on 70-90% mosquitoes during different months of intervention after 3 min of exposure and 100% mortality was recorded after 24h of recovery period. The median knockdown time for these species ranged between 4.10-5.25 min and 4.00-5.00 min respectively during intervention period. In Interceptor net study area, there was a significant reduction of 88.9, 96.3 and 90.6% in the entry rate of An. culicifacies, An. fluviatilis and other anopheline species respectively with an over all reduction of 87.5% in total mosquitoes. The overall feeding success rate of mosquitoes in the trial villages was only 12.8% in comparison to 35.0 and 78.8% in villages with untreated nets and no nets respectively. A significant reduction was also recorded in parity rate and human blood index of vector species in Interceptor net area. The results of the study showed that Interceptor nets are effective against the malaria vectors and may be used as a suitable intervention strategy in high-risk areas.

Persistence of DDT, malathion & deltamethrin resistance in Anopheles culicifacies after their sequential withdrawal from indoor residual spraying in Surat district, India

BACKGROUND & OBJECTIVES

Under the national antimalaria programme DDT was introduced in early 1950s for vector control and later hexachloro cyclohexane (HCH) followed by malathion and recently synthetic pyrethroids in 1990s to manage the insecticide resistance in Anopheles culicifacies. Subsequent replacement led to development of multiple resistances in An. culicifacies in Surat district in Gujarat State. Indoor residual spray (IRS) was completely withdrawn in southern villages in Surat in 2002. This study was undertaken in these areas to study the persistence of resistance to DDT, malathion and deltamethrin after sequential withdrawal of IRS with these insecticides at different times.

METHODS

Susceptibility tests on An. culicifacies were conducted using standard WHO methods and kits. Mortality, knockdown time and lethal times were calculated for An. culicifacies exposed to WHO prescribed diagnostic concentrations of different insecticide impregnated papers.

RESULTS

Persistence of DDT-resistance was observed even after 30 yr of its withdrawal from IRS. Similarly, persistence of malathion resistance was also observed after 9 yr of its withdrawal from IRS, while reversal of deltamethrin-resistance was observed very fast within 2-3 yr after its withdrawal from IRS in 2002.

INTERPRETATION & CONCLUSION

Present data indicate that the quantum of reversion of insecticide resistance in a population is relative and depends on the genetic stability of the respective resistance genes in the mosquitoes. In the present study withdrawal of pyrethroid-IRS resulted in increased susceptibility against pyrethroids alone and was independent of existence of resistance to insecticides of other groups. This study emphasizes that appropriate rotation of different insecticides; including carbamates may prevent or delay the onset of resistance.

Impact of temperature on susceptible and resistant strains of Culex quinquefasciatus to synthetic pyrethroids

Effect of temperature on the physiological activity and resistance status of Culex quinquefasciatus was studied. The LT(50) (lethal time) of deltamethrin, lambdacyhalothrin resistant and susceptible 4th-instar larvae decreased with increasing temperature. The LT(50) of deltamethrin resistant strains was significantly lower than the susceptible strains but not so in lambdacyhalothrin resistant strains. The developmental period of the thermal exposed and non-exposed larvae of resistant strains were nearly equal, however a significant difference was observed in case of susceptible strain. The thermal exposed susceptible larvae developed 3.3 days faster than the thermal un-exposed population. The percentage of survival of thermal exposed and un-exposed resistant strains were nearly equal. However, the thermal exposed population survived 12.9% less than the thermal un-exposed susceptible population. Longevity of thermal exposed deltamethrin and lambdacyhalothrin resistant females was significantly higher than the un-exposed population. The longevity of thermal exposed susceptible population was lower than the un-exposed population. The resistance of both the deltamethrin and lambdacyhalothrin resistant strains increased when exposed to high temperature for 3h. The difference in longevity between thermal un-exposed and exposed resistant male population was not significantly different. Among the un-exposed population, highest pupation was recorded in the susceptible strains, and lowest in the deltamethrin resistant strain. The fact that the thermal exposed resistant strains were more successful than the un-exposed population could be related to the presence of resistant gene.

Wash resistance and residual efficacy of long-lasting polyester netting coated with alpha-cypermethrin (Interceptor) against malaria-transmitting mosquitoes in Assam, northeast India

Malaria is endemic in Assam, northeast India, with low-to-moderate transmission of the causative parasites, mostly by Anopheles minimus. Plasmodium falciparum is the predominant parasite (>60%), with remaining cases being due to P. vivax. As an alternative intervention for malaria control, long-lasting insecticidal nets [Interceptor coated with alpha-cypermethrin 10% suspension concentrate (SC), 0.667% w/w, 0.2g/m(2)] underwent field evaluation for laboratory wash resistance and residual efficacy in field conditions against malaria-transmitting mosquitoes. Based on entomological observations, the Interceptor net intervention was the most effective, corresponding to the lowest mosquito vector density in experimental villages. There was virtual disappearance of A. minimus in Interceptor net villages in contrast to the untreated net intervention and the no-net control. Contact cone bioassay tests revealed 100% mortality in the A.minimus group of mosquito species in the community using the Interceptor net, which was consistent during the follow-up monitoring period (October 2006 to April 2007) in field conditions. Similar levels of mortality were observed in laboratory-washed nets compared with unwashed nets, and wash resistance was consistent even after the 20th serial wash at fortnightly intervals. Community compliance and acceptance of the Interceptor net was high, with decreased nuisance due to biting mosquitoes and other household insect pests being reported.

Laboratory studies on mosquito larvicidal efficacy of aqueous & hexane extracts of dried fruit of Solanum nigrum Linn

BACKGROUND & OBJECTIVE

Aqueous and organic solvent extracts of plants/plant parts were effective in killing the mosquito larvae. Comparative efficacy of the aqueous and hexane extracts of dried fruit of Solanum nigrum was tested against five laboratory colonized strains of mosquito species, namely Anopheles culicifacies species A, An. culicifacies species C, An. stephensi, Culex quinquefasciatus and Aedes aegypti to assess the possibility for use of these extracts for their control.

METHODS

Concentrations of aqueous extract of dried fruit in the range of 62.5 to 2000 ppm and hexane extract of dried fruit in the range of 0.781 to 150 ppm were used in bioassays. The mortality data were subjected to log probit regression analysis to determine the median lethal concentrations (LC(50) and LC(90)) to kill 50 and 90 per cent of the treated larvae of the respective species.

RESULTS

All the five species registered 100 per cent mortality in larval bioassays at 1000 ppm with aqueous extract and at 100 ppm with hexane extract of dried fruit. In bioassays with aqueous extract An. culicifacies species A registered the lowest LC(50) of 208.5 ppm (range-208.5-359 ppm for different mosquito species) while with hexane extract, An. stephensi registered the lowest LC(50) of 6.25 ppm (6.25- 17.63 ppm for different mosquito species). The LC(50) of aqueous extract was 13-39 fold higher than the values of hexane extract of dried fruit for different species. The calculated LC(90) for hexane extract of dried fruit for different species was in the range of 43.38-95.28 ppm.

INTERPRETATION & CONCLUSION

Hexane extract showed good mosquito larvicidal efficacy than that of the aqueous extract. The calculated LC(90) for the extract for different species was below 100 ppm and could be effective for comprehensive control of disease vectors.

Temporal-scale spectral variability analysis of water quality parameters to realize seasonal behaviour of a tropical river system--River Cauvery, India

This paper describes the Time series analysis of river water quality with emphasis on variation in parameters as evidenced by statistical approach and mathematical models. The extensive study enabled to differentiate and realize the behaviour of river and catchment's changes induced by human activities. The Time series analysis evaluation indicated trivial variation and movement in the water quality as reflected by the changes in the catchment characteristics. Although the observed trends showed an insignificant human contribution to basin hydrology and river water chemistry, noticeable human activities and unsustainable practices steadily contributed to change in water quality from the existing long term spectral signatures to short term spectral signatures. It is inferred that short term spectral signature exhibited on temporal scale by a monitoring program of this kind reflects an insalubrious river system and long term gradual changes in spectrum is an indication of healthy system. Monitoring and analyses of these decisive changes in water quality parameters over a period could be a powerful tool for assessing general river water quality and management plan.

Field evaluation of Olyset nets: a long-lasting insecticidal net against malaria vectors Anopheles culicifacies and Anopheles fluviatilis in a hyperendemic tribal area of Orissa, India

A village-scale trial was conducted on the efficacy of Olyset nets: a long-lasting insecticidal net (LLIN) factory treated with 2% wt:wt permethrin against malaria vectors Anopheles culicifacies Giles and Anopheles fluviatilis James, in Sundargarh District, Orissa, India. The study area comprised 22 villages that were randomized into three clusters and designated as Olyset net, untreated net, and no net clusters. Baseline studies showed that both vector species were 100% susceptible to permethrin. Results of wash resistance and bioefficacy of Olyset nets showed 100% mortality in An. culicifacies up to 11 washings, whereas 100% mortality was observed in An. fluviatilis even after 20 washings. The median knock-down time for these species ranged between 4.55-6.00 and 4.45-5.45 min, respectively, during 1 yr of intervention. In the Olyset net study area, there was a significant reduction of 80.6, 94.1, and 76.7% in the entry rate of An. culicifacies, An. fluviatilis, and other anopheline species, respectively, with an overall reduction of 63.5% in total mosquitoes. Floor sheet collections in houses with Olyset nets indicated 39% immediate mortality in total mosquitoes. The overall feeding success rate of mosquitoes in the trial village was only 18.0% in comparison to 44.2 and 79.1% in villages with untreated nets and no nets, respectively. A significant reduction was also recorded in parity rate and human blood index of vector species in the Olyset net area. This study showed that Olyset nets are an effective personal protection tool that can be used in a community-based intervention program.

Wash resistance and efficacy of three long-lasting insecticidal nets assessed from bioassays on Anopheles culicifacies and Anopheles stephensi

OBJECTIVE

To test the wash resistance and efficacy of long-lasting insecticidal nets (LLINs), namely Olyset Net and PermaNet 2.0; and a long-lasting treatment kit, K-O Tab 1-2-3, on Anopheles culicifacies and An. stephensi, major malaria vectors in India, by bioassays. Conventionally treated deltamethrin net (CTDN with K-O Tab) was used for comparison.

METHOD

Mortality and median time for knockdown (MTKD) of mosquitoes were determined using contact bioassays and ball frame bioassays respectively. Hand washing and machine washing were used.

RESULTS

LLINs showed good bio-efficacy against An. culicifacies and An. stephensi. The mortality of mosquitoes remained >80% after up to 20 hand washes and up to 15 machine washes on all LLINs tested. No significant differences were observed in mortalities between the An. culicifacies and An. stephensi in cone bioassays (P > 0.05). MTKD increased progressively with successive washes and there was a significant difference in median time for knockdown of test mosquitoes and between hand-washed and machine-washed nets (P < 0.05).

CONCLUSION

LLINs are more efficacious and last longer when washed by hand than by machine.

Characterization of biochemical based insecticide resistance mechanism by thermal bioassay and the variation of esterase activity in Culex quinquefasciatus

Biochemical mechanisms of insecticide resistance of thermal exposed and unexposed Culex quinquefasciatus strains are evaluated, which were not studied earlier. The activity of alpha- and beta-carboxylesterases and acetylcholinesterase of malathion susceptible and resistant strains were compared after thermal treatment. Three-day-old adult females were used for the malathion susceptibility test and biochemical assays, and males were used only for the susceptibility test. Thermal exposure brought about increase in resistance levels from 85% to 90% in males and 91% to 96.6% in females of resistant strain. The resistance status of the susceptibility strain was unchanged after thermal exposure. The activities of alpha- and beta-carboxylesterase of susceptible mosquitoes were within 800 and 700 U/mg protein, respectively. The alpha-carboxylesterase activity of the thermal exposed malathion-resistant population was significantly (t test, P < 0.05) higher than the unexposed resistant population, and the reverse was recorded in beta-carboxylesterase. The alpha-carboxylesterase activity of susceptible population was lower than the resistant population. The activity of alpha-carboxylesterase was higher than the beta-carboxylesterase in both the strains. Among the malathion resistant C. quinquefasciatus population, 2.3% population exhibited 30-40% inhibition which increased to 5.8% after the thermal exposure. Thermal exposure of mosquitoes increased the activity of both alpha-carboxylesterases and acetylcholinesterase but decreased the activity of beta-carboxylesterase.

Multiplex PCR assay and phylogenetic analysis of sequences derived from D2 domain of 28S rDNA distinguished members of the Anopheles culicifacies complex into two groups, A/D and B/C/E

A multiplex PCR assay was developed using the sequences of the D2 region of 28S ribosomal DNA (rDNA) to discriminate the five members of the Anopheles culicifacies complex provisionally designated as species A, B, C, D and E. Two minus strand primers derived from sequence differences in the D2 variable region and a universal plus strand primer derived from the conserved 28S (rDNA) has delimited five members into species A and D (group 1) and species B, C and E (group 2) in a PCR diagnostic assay. The complete 28S rDNA-D2 region sequence of A. culicifacies sibling species is reported for the first time. Inter-specific sequence divergence was greater than the intra-specific divergence. The phylogenetic relationships inferred from maximum likelihood, maximum parsimony and the neighbor joining analysis confirmed the presence of two unambiguous monophyly clades one consisting of species A and D and the other of species B, C and E and that the A. culicifacies sibling species diverged relatively recently in evolutionary terms despite their considerable differences in bionomics.

Evaluation of Tribulus terrestris Linn (Zygophyllaceae) acetone extract for larvicidal and repellence activity against mosquito vectors

Acetone extracts of leaves and seeds from the Tribulus terrestris (Zygophyllaceae) were tested against mature and immature different mosquito vectors under laboratory condition. The extract showed strong larvicidal, properties 100 per cent mortality in the 3rd-instar larvae was observed in the bioassays with An. culicifacies Giles species A, An. stephensi Liston, Culex quinquefasciatus Say and Aedes aegypti Linn, against 200 ppm of the leaf acetone extract and 100 ppm seed acetone extract. The LC50 values of leaf acetone extract estimated for 3rd-instars An. culicifacies species A, An. stephensi, Cx. quinquefasciatus and Ae. aegypti after 24 hour of exposure were 117, 124, 168 and 185 ppm respectively. The LC50 values of seed acetone extract estimated for 3rd-instars An. culicifacies species A, An. stephensi, Cx. quinquefasciatus and Ae. aegypti after 24 hour of exposure were 100, 72, 91 and 91 ppm respectively. It is confirmed from the LC50 values that the seed acetone extract of T. terrestris is more effective compared to leaf extracts. A significant (P<0.004) higher concentration of acetone extract leaf was required to kill equal number of larvae i.e. against acetone extract of seed. The seed acetone extract showed strong repellent activity against adults mosquitoes. Per cent protection obtained against Anopheles culicifacies species A 100% repellency in 1 h, 6 h; Anopheles stephensi 100% repellency in 0 h, 4 h, 6 h; and Culex quinquefasciatus 100% repellency in 0 h, 2 h, 4 h, at 10% concentration respectively. Against Deet- 2.5% An. culicifacies Giles species A has shown 100% repellency in 1 h, 2 h, 6 h, An. stephensi Liston 99% repellency in 4 h, and Culex quinquefasciatus Say has shown 100% repellency in 1 h, 2 h.

Field evaluation of a previously untested strain of biolarvicide (Bacillus thuringiensis israelensis H14) for mosquito control in an urban area of Orissa, India

A previously untested strain of Bacillus thuringiensis israelensis (Bti) serotype H14 (ID No. VCRC B17) has been evaluated under field conditions in an urban area of Rourkela city, India for its impact on the larval density of different mosquito species in a variety of habitats. The persistence of the biolarvicide used in an aqueous solution varied in different habitats. The lowest field application rate of 0.5 ml/m2 remained effective for about 10-12 days and provided 80-100% reduction in larval abundance of anopheline species, including Anopheles culicifacies breeding in unpolluted water bodies. However, in stagnant polluted waters in drains and cesspools supporting culicine breeding, the biocide at the same rate persists for 5-6 days only. An application rate of 1 ml/m2 to stagnant drains and cesspools, resulted in 84-100% reduction in the larval population of Culex quinquefasciatus over a period of 2 wk. Based on the field observations, an operational dose of 0.5 ml/m2 at fortnightly intervals is suggested for clean water sources supporting anopheline breeding. However, to control breeding of culicine mosquitoes in stagnant and polluted waters, an operational dose of 1 ml/m2 at fortnightly intervals is required. The study showed that Bti serotype H14 (VCRC B17) is a suitable biolarvicide that can be used against different mosquitoes in different types of urban habitats.

Biological control of mosquito populations through frogs: opportunities & constrains

The use of frogs and tadpoles for disease vector control is still largely unexplored. Frogs are an important part of the ecosystem with a role for insect and pest control including mosquitoes. Available information suggests the existence of many direct and indirect factors affecting the growth and survival of both prey and predators. Other controphic species that have influence on this relationship also show considerable effect. Still, the associations of different prey and predator relationships in the environment to assess the feasibility of use of a species as biocontrol agent for vector control and management. However, frogs cannot be used as an independent intervention for disease vector control and more research is needed to use them effectively for mosquito control.

Effect of temperature on development, eclosion, longevity and survivorship of malathion-resistant and malathion-susceptible strain of Culex quinquefasciatus

Density of vectors and development of resistance against insecticides are two important aspects in the control of vector-borne diseases. Here, effect of temperature on different aspects of development of malathion-resistant and susceptible strains of Culex quinquefasciatus was evaluated in the laboratory. Fourth-instar larvae of C. quinquefasciatus were exposed to 37 degrees C, 39 degrees C, 40 degrees C, and 41 degrees C, and their LT(50) values calculated. The fourth-instar larvae were subjected to heat for 4 h at 39 degrees C and live larvae were reared until the completion of life cycle. The larvae of malathion-resistant strain were more tolerant to heat than the larvae of malathion-susceptible ones. The difference in mortality between 37 degrees C, 39 degrees C, 40 degrees C, and 41 degrees C of both the strains of C. quinquefasciatus were highly significant. Pupation percentage of heat-exposed larvae of both the strains was higher and delayed than the control ones. The percentage of adult emergence from the heat-exposed larvae was significantly lower than the control. The adult female of malathion-resistant strain showed increased longevity when exposed to heat at larval stage but reverse was true in case of malathion-susceptible. The highlights of the study would help in the management of resistance of mosquito vectors in the tropics where variable climatic condition is observed.