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INTRODUCTION: The ongoing visceral leishmaniasis (VL) elimination programme in India is targeting the elimination of the disease VL but not the pathogen. The persistence of hidden parasite pool may initiate a resurgence in suitable conditions. This study dealt with a novel approach to unearth such pathogen pool and their proper management to prevent the resurgence of VL. MATERIALS AND METHODS: We deployed a new approach for detection of pathogen pool by following up the VL and post kala-azar dermal leishmaniasis patients treated during the last 10 years along with mass sero-surveillance within a radius of 500 m of recently treated individuals. RESULTS: We followed up 72.6% (3026/4168) previously treated VL and post kala-azar dermal leishmaniasis patients and diagnosed 42 (1.4%) new and 38 (1.3%) recurrent post kala-azar dermal leishmaniasis. We detected 93 asymptomatic leishmanial infection, 8 VL and 1 post kala-azar dermal leishmaniasis by mass sero-surveillance. CONCLUSION: Our three-step process including mapping and follow-up of previously treated cases, mass surveillance within 500 m of radius of known cases, and 6 monthly follow-on clinical and serological screening of asymptomatic cases, enabled detection of previously undetected cases of post kala-azar dermal leishmaniasis and VL. Recurrent post kala-azar dermal leishmaniasis deserves special attention regarding their treatment guideline. Early diagnosis and effective treatment of all leishmaniasis cases will hasten pathogen elimination and prevent resurgence of VL. This may help the policymakers to develop appropriate strategy for elimination of pathogen to prevent resurgence of VL.
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Context: Resistance to antimalarial drugs is one of the major challenges for malaria elimination. In India, artemisinin combination therapy (artesunate-sulfadoxin pyrimethamine) was introduced in place of chloroquine (CQ) for the treatment of uncomplicated falciparum malaria in 2010. Periodical monitoring of polymorphisms in antimalarial drug resistance marker genes will be useful for assessing drug pressure, mapping and monitoring of drug resistance status; and will be helpful for searching alternative treatments. Objectives: This study was conducted to study the polymorphisms in antimalarial drug resistance marker genes among clinical Plasmodium falciparum isolates collected from Kolkata after 10 years of artemisinin-based combination therapie (ACT) implementation. Materials and Methods: Blood samples were collected from P. falciparum mono-infected patients and polymorphisms in P. falciparum CQ resistance transporter (pfcrt), P. falciparum multidrug resistance (pfmdr-1), P. falciparum dihydrofolate reductase (pfdhfr), P. falciparum dihydropteroate synthetase (pfdhps), pfATPase6 and pfK-13 propeller genes were analysed by polymerase chain reaction and DNA sequencing. Results: In pfcrt gene, C72S, and K76T mutation was recorded in 100% isolates and no mutations was detected in any of the targeted codons of pfmdr-1 gene. A double mutant pfcrt haplotype SVMNT and wildtype haplotype NYD in pfmdr-1 were prevalent in 100% of study isolates. Triple mutant pfdhfr-pfdhps haplotype ANRNI-SGKAA was recorded. No polymorphism in pfK13 gene was documented in any of the isolates. Conclusions: Observed wild codon N86 along with Y184 and D1246 of pfmdr-1 gene might be an indication of the reappearance of CQ sensitivity. The absence of quadruple and quintuple haplotypes in pfdhfr-pfdhps gene along with the wild haplotype of pfK13 is evidence of ACT effectivity. Hence, similar studies with large sample size are highly suggested for monitoring the drug resistance status of P. falciparum.
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BACKGROUND: India is going through the maintenance phase of VL elimination programme which may be threatened by the persistence of hidden parasite pools among asymptomatic leishmanial infection (ALI) and PKDL. The present work was designed to determine the burden of VL, PKDL, and ALI and to assess the role of treatment of ALI in maintaining post-elimination phase. METHODS AND FINDING: The study was undertaken in Malda district, West Bengal, India during October 2016 to September 2021. Study areas were divided into 'Study' and 'Control' arms. VL and PKDL cases of both the arms were diagnosed by three active mass surveys with an interval of one year and treated as per National guideline. ALI of 'Study' arm was treated like VL. ALI of 'Control' arm was followed up to determine their fate. Fed sand-fly pools were analysed for parasitic DNA. No significant difference was noted between the incidence of VL and PKDL in both the arms. Incidence of ALI declined sharply in 'Study' arm but an increasing trend was observed in 'Control' arm. Significantly higher rate of sero-conversion was noted in 'Control' arm and was found to be associated with untreated ALI burden. Parasitic DNA was detected in 22.8% ALI cases and 2.2% sand-fly pools. CONCLUSION: Persistence of a significant number of PKDL and ALI and ongoing transmission, as evidenced by new infection and detection of leishmanial DNA in vector sand-flies, may threaten the maintenance of post-elimination phase. Emphasis should be given for elimination of pathogen to prevent resurgence of VL epidemics.
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Leishmania donovani , Leishmaniasis, Cutaneous , Leishmaniasis, Visceral , Phlebotomus , Psychodidae , Animals , Leishmaniasis, Visceral/epidemiology , Leishmaniasis, Visceral/prevention & control , Leishmaniasis, Visceral/complications , Sand , Psychodidae/parasitology , Asymptomatic Infections/epidemiology , India/epidemiology , DNA , Leishmaniasis, Cutaneous/epidemiologyABSTRACT
Immunocompromised patients with human immunodeficiency virus (HIV) infection are prone to multiple infections, of which parasitic infections are an important cause. Parasitic protozoal infections - both by common and rare protozoa are documented in such patients. Here, we report a rare and interesting case of five protozoal infections affecting a single HIV-infected person at the same time of initial presentation. A 64-years-male came to us with complaints of chronic diarrhea for 6 months. He was investigated and found to be positive for HIV I. His stool examination revealed cysts of Entameba histolytica and Giardia lamblia and oocysts of Cryptosporidium species and Cystoisospora species. His toxoplasma IgG was also positive in high titer. The patient was medically diagnosed and was treated with medications as clinically prescribed - antiretroviral therapy was initiated and he was discharged in due course. A total of five protozoal infections were documented affecting a single person - newly diagnosed immunocompromised male, which by sheer qualitative count of patient case histories, indeed is a rare case reported in the medical literature.
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Context: Histidine-rich protein 2 (HRP2) detecting rapid diagnostic tests (RDTs) have played an important role in enabling prompt malaria diagnosis in remote locations. HRP2 has advantages over other biomarkers because of its abundance in the bloodstream, repetitive binding epitopes, and falciparum-specificity. Most HRP2-based RDTs also exhibit some cross-reactivity to a closely related protein (HRP3). Plasmodium falciparum parasites lacking HRP2 (pfhrp2) and 3 (pfhrp3) genes escape detection by these RDTs. Objectives: The objective of the study was to study the sensitivity and specificity of hrp2-based RDT for diagnosis of falciparum, to compare the RDT results with microscopy and polymerase chain reaction (PCR), and to determine the prevalence of HRP2 gene deletion among the RDT-negative, microscopy-positive falciparum strains. Materials and Methods: Blood samples were collected and diagnosis was done by microscopic examination, RDTs, and PCR. Results: Out of 1000 patients examined, 138 were positive for P. falciparum. Fever was the most common symptom followed by chills with rigor and headache were recorded among more than >95% of the study patients. Three microscopy-confirmed P. falciparum cases were negative by HRP2-based RDT and were found to have deletion of HRP2 and HRP3 exon 2. Conclusions: Rapid and accurate diagnosis and prompt deployment of effective antimalarial medication are essential components of appropriate case management. P. falciparum strains that evade diagnosis by RDTs represent a major threat to malaria control and elimination efforts.
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BACKGROUND & OBJECTIVES: Community participation is one of the key factors for implementation and success of a public health programme which depends upon knowledge about that disease. Therefore, understanding the community knowledge about malaria is important for designing sustainable control programmes. This study was conducted to assess the knowledge about malaria, to evaluate long lasting insecticidal nets (LLINs) distribution and their use by LQAS method in endemic areas of Bankura district, West Bengal state, India Methods: It was a community based cross-sectional survey conducted in Bankura during December 2019-March 2020. Structured questionnaire under four categories: socio-demographic variables, knowledge of malaria, owner ship of LLINs and its use were used for the interview. Ownership of LLINs and its use were analysed by LQAS method. Data were analysed by binary logistic regression model and chi-squared test. RESULTS: Out of 456 respondents, 88.59% had good knowledge, 97.37% had good ownership of LLIN and 78.95% used LLINs properly. The knowledge about malaria was significantly associated with education level (p-value<0.0001). Out of 24 lots studied, 3, 2, 4 lots were underperforming with respect to knowledge, ownership of LLIN and its use, respectively. INTERPRETATION & CONCLUSION: The study population had a good knowledge about malaria. In spite of good coverage of LLIN distribution, the use of LLINs was not up to the mark. LQAS analysis showed underperformance in few lots about knowledge, ownership of LLIN and its use. The IEC and BCC activities about LLIN should be done to achieve the impact of this intervention at the community level.
Subject(s)
Insecticide-Treated Bednets , Insecticides , Malaria , Humans , Ownership , Cross-Sectional Studies , Mosquito Control/methods , Malaria/epidemiology , Malaria/prevention & control , India/epidemiologyABSTRACT
BACKGROUND: Japanese encephalitis (JE) is an emerging zoonotic disease caused by JE virus (JEV) and transmitted to humans from pigs or aquatic birds by vector mosquitoes in southeast Asian countries. In this study, JEV infection rate among vector mosquitoes and domestic pigs was determined by detecting viral RNA and anti-JEV antibody (immunoglobulin G), respectively. MATERIALS AND METHODS: A total of 146 pool mosquitoes of Culexvishnui subgroup and 278 pig blood samples were analyzed by reverse transcriptase polymerase chain reaction and enzyme-linked immunosorbent assay methods, respectively. E and premembrane (PrM) gene of JEV detected among vectors were sequenced and a phylogenetic tree was constructed. RESULTS: Five (5.81%) pools of Culextritaeniorhynchus were positive for JEV with pooled infection rate 1.70/1000 mosquitoes. A total of 108 (38.84%) blood samples were positive for anti-JEV antibody. Phylogenetic analysis revealed that our own E and PrM gene sequence of JEV belonging to Genotype III and showed 96.95% sequence similarities with the vaccine strain SA14-14-2. CONCLUSION: It was observed that domestic pigs of northern West Bengal were highly infected with JEV. Hence, the transmission should be blocked by pig vaccination. A pilot study may be undertaken for mass vaccination of the prevailing pig population to observe any reduced rate of JEV transmission from both pig to pig and pig to human.
Subject(s)
Culex , Encephalitis Virus, Japanese , Encephalitis, Japanese , Mosquito Vectors , Animals , India/epidemiology , Encephalitis, Japanese/epidemiology , Encephalitis, Japanese/transmission , Encephalitis, Japanese/veterinary , Encephalitis, Japanese/virology , Swine , Encephalitis Virus, Japanese/isolation & purification , Encephalitis Virus, Japanese/genetics , Mosquito Vectors/virology , Culex/virology , Phylogeny , Enzyme-Linked Immunosorbent Assay , Antibodies, Viral/blood , Swine Diseases/virology , Swine Diseases/epidemiology , Reverse Transcriptase Polymerase Chain Reaction , RNA, ViralABSTRACT
Introduction: Co-infection with different agents such as bacterial, viral, and Rickettsia is being increasingly recognized due to greater availability and utilization of the diagnostic tests among malaria patients. Methods: Consecutive admitted malarial cases were included and were subjected to test for general investigations, bacteria, typhoid, dengue, chikungunya, and rest for specific diagnosis. All patients were followed up till discharge or death and appropriate statistical tests were performed. Results: A total of 152 malaria patients were recruited and 27 (18.8%) had concurrent infections. It included 40.7% dengue only, 18.7% pneumonia, 11.1% urinary tract infection (UTI), 7.4% enteric fever, 3.7% leptospirosis, chikungunya, and tuberculous meningitis each, and 3.7% each of dengue with pneumonia and UTI. The organisms isolated were Streptococcus pneumoniae, Klebsiella pneumoniae, Escherichia coli, Salmonella typhi, and Mycobacterium tuberculosis. The mean duration of fever was 6.33 ± 3.63 days with a range of 3-20 days. Blood culture grew in 2 cases S. typhi and K. pneumonia,e. Dengue co-infections had significantly higher clinical and laboratory features of dengue and complications such as bleeding, jaundice, and cholecystitis, whereas rest concurrent infections had a significantly higher proportion of nausea and vomiting, convulsion, altered sensorium, productive cough, urinary symptoms, shock, acute kidney injury, anemia, and mean neutrophil count. There was significantly higher mortality among malaria-dengue concurrent infection group with 2 (15.4%) than malaria mono-infection group 3 (2.4%). Conclusion: Co-infections with malaria are not uncommon, especially dengue fever and other bacterial infections. The dominant clinical picture is of the superimposed infection. Decision should be clinically guided adjunct with specific diagnostic tests, and timely treatment has favorable outcome.
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Enterobius vermicularis, also known as pinworm or threadworm, is a large intestinal nematode which has a high prevalence among children and peripubertal age in our country. Transmission usually occurs by autoinfection like finger contamination of the embryonated eggs deposited by the gravid female worm on the perianal and perineal region. Globally, only a few reports are there regarding the isolation of the parasite from extra-intestinal sites. These are two rare case reports of ocular enterobiasis. The first case was a middle-aged female and the second one was a 14-year-old girl, both of whom were referred from other tertiary care hospitals to Calcutta School of Tropical Medicine and who presented with discharge of live motile worms from their eyes (conjunctiva). In both the cases, identification was done by saline wet mount and direct microscopy of a gravid female worm. Plano-convex embryonated eggs were also observed. The oval embryonated eggs, plano-convex in shape, and the gravid female, with its cervical alae near the anterior end and straight thin pointed tail, were identified under the microscope. Although E. vermicularis is a very common large intestinal parasitic infestation of children and adolescents, it can also rarely be isolated from unusual sites, which should be taken into account for effective diagnosis and treatment.
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Kala-azar or visceral leishmaniasis was at one time a scourge in the Bengal Presidency of British India comprising the present Indian states of Bengal, Bihar, Assam, and Odisha. The disease was rampant along the Ganga and Brahmaputra River adjoining areas. In the early 1900s, the treatment initiated was by the intravenous injection of tartar emetic, which had a narrow safety level and long-term use was marked with multiple side effects. In 1920, Upendranath Brahmachari discovered urea stibamine, which is the urea salt of para-amino phenyl stibnic acid and it revolutionized the treatment of Kala-azar with >90% cure rate and with minimal side effects. He is also credited with the description of post-kala-azar dermal leishmaniasis. He was conferred the knighthood of the British Empire as recognition of his important contribution. Although his name was twice nominated for Nobel Prize, unfortunately, he never received it.
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CONTEXT: Screening for malaria and coronavirus disease (COVID-19) in all patients with acute febrile illness is necessary in malaria-endemic areas to reduce malaria-related mortality and to prevent the transmission of COVID-19 by isolation. AIMS: A pilot study was undertaken to determine the incidence of SARS-CoV-2 infection among febrile patients attending a malaria clinic. SUBJECTS AND METHODS: All patients were tested for malaria parasite by examining thick and thin blood smears as well as by rapid malaria antigen tests. COVID-19 was detected by rapid antigen test and reverse transcriptase-polymerase chain reaction in patients agreeing to undergo the test. RESULTS: Out of 262 patients examined, 66 (25.19%) were positive for Plasmodium vivax, 45 (17.17%) for Plasmodium falciparum (Pf) with a slide positivity rate of 42.40%, and Pf% of 40.50%. Only 29 patients consented for COVID-19 testing along with malaria; of them, 3 (10.34%) were positive for COVID-19 alone and 2 (6.89%) were positive for both COVID-19 and P. vivax with an incidence of 17.24%. A maximum number of patients (196) did not examine for COVID-19 as they did not agree to do the test. CONCLUSION: Diagnosis of COVID-19 among three patients (10.34%) is significant both in terms of identification of cases and to isolate them for preventing transmission in the community. Detection of COVID-19 along with malaria is equally important for their proper management.
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Community participation is an important aspect for the success of kala-azar (KA) elimination program implemented in five Southeast Asian countries by the WHO. The participation of community depends on the level of knowledge of, attitude toward, and practice around risk factors associated with KA transmission among the population. We assessed the knowledge, attitude, and practice toward KA elimination in endemic areas of Malda district, West Bengal, India. A total of 709 individuals from different villages of 12 sub-centers were interviewed during April-July 2019. Data were recorded in a structured questionnaire under four categories: sociodemographic parameters, knowledge, attitude, and practice. The association of dependent variables such as knowledge, attitude, and practice with independent variables such as the economy and sociodemographic parameters was analyzed by binary logistic regression model and chi-square test using SPSS software. Despite the endemicity of the disease for a long time, the adequacy of knowledge about the disease was found to be poor that can be attributed to low education level and socioeconomic status, but the attitude and practices were good. So, there is a scope of improvement in knowledge of the disease through proper health education. This will further improve the level of attitude and practices that will be helpful for the smooth implementation of different activities of the program by more active participation of the community.
Subject(s)
Health Knowledge, Attitudes, Practice , Leishmaniasis, Visceral/epidemiology , Leishmaniasis, Visceral/psychology , Adult , Animals , Cross-Sectional Studies , Endemic Diseases , Female , Humans , India/epidemiology , Insect Vectors/parasitology , Leishmaniasis, Visceral/transmission , Male , Psychodidae/parasitology , Rural Population/statistics & numerical data , Social Class , Young AdultABSTRACT
Vector control is one of the main aspects to reach the target of eliminating visceral leishmaniasis from Indian sub-continent as set by the World Health Organisation. Data on different aspects of vector like ecology, behaviour, population dynamics and their association with environmental factors are very important for formulating an effective vector control strategy. The present work was designed to study the species abundance and impact of environmental factors on population dynamics of vector P. argentipes in a visceral leishmaniasis endemic area of Malda district, West Bengal. Adult sand flies were collected using light traps and mouth aspirators from twelve kala-azar affected villages of Habibpur block of Malda district, on a monthly basis from January to December, 2018. Morphological and molecular methods were used for species identification. Population dynamics were assessed by man hour density and per night per trap collection. Data were analysed using SPSS software to determine the impact of environmental factors on vector population P. argentipes was found to the predominant species and prevalent throughout the year. A significantly higher number of sand flies were collected from cattle sheds than human dwellings and peri-domestic vegetation. A portion of the P. argentipes population was exophilic and exophagic as evidenced by their collection from peri-domestic vegetation. The highest population density was recorded during April to September. Population dynamics were mostly influenced by average temperature along humidity and rain fall. Resting behaviour of sand flies was not restricted to the lower portion of the wall but equally distributed throughout the wall and ceiling. Programme officials should consider management of outdoor populations of the sand flies and timings of indoor residual spray for chemical control purpose.
Subject(s)
Insect Vectors/physiology , Leishmaniasis, Visceral/epidemiology , Psychodidae/physiology , Animals , Cattle , Ecology , Housing, Animal , Humans , India/epidemiology , Insecticides , Leishmaniasis, Visceral/prevention & control , Population Density , Population Dynamics , TemperatureABSTRACT
CONTEXT: Both malaria and lymphatic filariasis (LF) are mosquito-borne diseases caused by protozoal and nematode parasites, respectively, and are serious public health problem in India. Although the vectors of the diseases are different, they can coexist in favorable conditions. Fever is the common symptom for both the diseases, but the emphasis is given for diagnosis and treatment of malaria due to its life-threatening severity, LF remained neglected. Detection and management of microfilaria are equally important. During the diagnosis of malaria, a few microfilaria were detected, which prompted us to undertake this study with following objectives. OBJECTIVES: The objective of the study was to determine the incidence of microfilaremia among the febrile patients attending for malaria diagnosis. SUBJECTS AND METHODS: Thick and thin peripheral blood smears from all patients attended were examined following Giemsa staining. Different malarial indexes were analyzed. RESULTS: Out of 8681 patients examined, 1778 were positive for Plasmodium vivax and 328 for Plasmodium falciparum with a slide positivity rate 20.48%. Twenty-six patients were positive for microfilaria of Wuchereria bancroftii among which five were coinfected with P. vivax and one with P. falciparum. Most of the microfilaria-positive patients were adult and originally from northern districts of Bihar. CONCLUSIONS: High incidence of microfilaria among febrile patients attending for malaria is alarming for urban Kolkata. Although the patients were originally from Bihar, they are staying in Kolkata for a long time, might be a source for transmission. Epidemiological study by collecting night blood samples and entomological survey is highly suggestive to explore local transmission if any.
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BACKGROUND: Aedes albopictus and Aedes aegypti are the major vectors of arboviral diseases. As effective vaccines are not available for most of the arboviral diseases, vector control by using insecticides play the key role to reduce the disease transmission. The emergence and spread of resistance to different classes of insecticides by the vectors is a major obstacle to control the disease transmission. Information about vector susceptibility to different insecticides and their mechanisms are very important for formulating proper vector control measures. The present study was designed to assess the susceptibility of Ae. aegypti against three different classes of adulticides, one larvicidal agent available and polymorphisms in the voltage-gated sodium channel (VGSC) gene related to insecticide resistance. METHODS: Immature stages of Ae. aegypti were collected from three dengue endemic municipal areas of West Bengal and reared in the laboratory. Larvae and adults (F1 progeny) were used for insecticide bioassay as per WHO protocols. Knock down resistance gene (kdr) mutations were assessed by direct sequencing of PCR products. RESULTS: The Ae. aegypti population was found to be susceptible to type II pyrethroids and malathion but highly resistant to DDT. A high rate of polymorphisms in the VGSC gene was observed among the collected mosquitoes. A double mutant V1016G + F1534C was found to be associated with DDT resistance but neither V1016G nor F1534C alone showed the same association. Association between the kdr mutations and the susceptibility status of pyrethroids could not be established due to very small sample size. A low to moderate level of resistance was noticed against temephos among the larval population based on WHO criteria. CONCLUSION: The replacement of DDT by type II pyrethroids for the management of dengue vectors is an appropriate decision taken by the national program which is supported by the findings of a higher level of resistance to DDT. Persistence of polymorphisms in the VGSC gene might be an indication of emergence of resistance against pyrethroid insecticides that should be monitored at a regular interval. Attempts should be made to determine the effectiveness of other larvicides for replacement of temephos if needed in future. Along with the chemical insecticides different biological vector control methods as well as biopesticides should also be used in vector control programmes.
Subject(s)
Aedes , Drug Resistance/genetics , Insect Proteins , Insecticides/pharmacology , Mutation , Pyrethrins/pharmacology , Voltage-Gated Sodium Channels , Aedes/enzymology , Aedes/genetics , Animals , Drug Resistance/drug effects , India , Insect Proteins/genetics , Insect Proteins/metabolism , Prevalence , Voltage-Gated Sodium Channels/genetics , Voltage-Gated Sodium Channels/metabolismABSTRACT
Rational use of insecticides, as advocated by World Health Organisation, plays a crucial role for vector control in eliminating visceral leishmaniasis from endemic countries. Emergence and spread of resistance among vector sand flies is of increasing concern for achieving these goals. Information on insecticide susceptibility status of sand fly populations and potential association between the former and polymorphisms in the insecticide target genes is important for formulating proper vector control measures. The present study was designed to evaluate the susceptibility status of vector sand fly species (Phlebotomus argentipes) against deltamethrin (type II pyrethroid), DDT (organochlorine) and malathion (organophosphate) and to detect polymorphisms in voltage gated sodium channel (vgsc) gene and investigating their association with type II pyrethroid and DDT susceptibility in three Kala-azar endemic districts of West Bengal, India. Adult sand flies were collected from human dwelling and cattle sheds of the study areas and subjected to insecticide bioassay using insecticide impregnated papers as per WHO protocol. Polymorphisms in domain II segment 6 of vgsc gene of pyrethroid and DDT susceptible and tolerant P. argentipes were detected by DNA sequencing. P. argentipes population of the study area was found to be susceptible to deltamethrin and malathion with corrected mortality rate between 98.02% to 98.80% and 98.81% to 100% respectively, but resistant to DDT (corrected mortality rateâ¯=â¯65.62%-76.33%). Two non-synonymous mutations L1014S and L1014F were detected of which L1014F was found to be associated with deltamethrin/DDT resistance. The replacement of DDT by synthetic pyrethroid is aptly done by national vector borne disease control programme (NVBDCP). The prevalence of L1014F mutation in vgsc gene and its association with type II pyrethroid tolerability is an indication of emergence of resistance against it. Malathion may be used as an alternative in the study areas if needed in future. Similar studies at a regular interval are highly suggested for monitoring susceptibility of used insecticide and to detect early signs of emergence of resistance against them.
Subject(s)
Insecticide Resistance/genetics , Insecticides/pharmacology , Phlebotomus/drug effects , Polymorphism, Genetic , Voltage-Gated Sodium Channels/genetics , Animals , Humans , India , Phlebotomus/geneticsABSTRACT
BACKGROUND: The control and prevention of dengue largely depends on vector control measures, environmental management, and personal protection. Dengue control programmes are facing great challenges due to development of insecticide resistance among vector mosquitoes. Information on susceptibility status to different insecticides is important for national programmes to formulate vector control strategies. METHODS: We have studied the larval susceptibility of Aedes albopictus to temephos and adult susceptibility to 4% DDT, 0.05% deltamethrin, and 5% malathion as per WHO protocols in the northern districts of West Bengal. Polymorphisms in the VGSC gene were studied by direct sequencing of PCR products. RESULTS: The Ae. albopictus larval population showed sensitive [Resistance Ratio (RR99)<3] to moderate levels of resistance (5
Subject(s)
Aedes/drug effects , Aedes/genetics , Insecticides/pharmacology , Polymorphism, Genetic , Voltage-Gated Sodium Channels/genetics , Animals , Biological Assay , India , Insecticide Resistance , Polymerase Chain Reaction , Sequence Analysis, DNAABSTRACT
Resistance to almost all available antimalarial agents, particularly for Plasmodium falciparum, is an important issue throughout all malaria endemic countries. Recently, Plasmodium vivax also showed resistance to chloroquine in some part of the World. Monitoring efficacy of used antimalarial drugs plays an important role to determine the emergence of resistant power by the prevailing parasite population of a geographical area if any. There are four different methods for antimalarial drug efficacy study. In vivo therapeutic efficacy study remains the gold standard and provides primary data for formulating antimalarial drug policy by the National Malaria Control Programmes. Several in vitro assay methods for assessing antimalarial drug susceptibility have been developed during past few decades. These assay methods are simple, easier to handle and allow early detection of drug-resistant parasites and also for the screening of different newly developed agents for their antimalarial activity. Approaches of different assay methods for testing the susceptibility of antimalarial agents and their limitations are discussed in this review article.
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Emergence and spread of resistance among vectors toward different insecticides is a serious problem for the Japanese encephalitis (JE) control program. Regularly monitoring the status of susceptibility of vector species to insecticides is important for formulating proper vector control measures. In this study, we studied the susceptibility status of major JE vectors from northern West Bengal, toward 4% DDT, 0.05% deltamethrin, and 5% malathion. Two- to three-day-old unfed female mosquitoes were subjected to a susceptibility bioassay using a World Health Organization kit. Corrected mortality (CM) and knockdown times were estimated. Culex tritaeniorhynchus, Cx. vishnui, Cx. pseudovishnui, and Cx. gelidus were the major JE vectors present in the study areas. All 4 vector species were highly tolerant to DDT with CM ï¼ 90%. Cx. tritaeniorhynchus, Cx. vishnui, Cx. pseudovishnui, and Cx. gelidus were tolerant to deltamethrin with CM ï¼ 90%, except for Cx. gelidus of Darjeeling and Malbazar. At most of the study sites, malathion was effective against Cx. vishnui, Cx. pseudovishnui, and Cx. gelidus with CM ≥ 98%. In contrast, Cx. tritaeniorhynchus was tolerant to malathion in all study areas. Predominant JE vector populations were highly tolerant to all 3 analyzed insecticides, except deltamethrin for Cx. gelidus and malathion for Cx. vishnui, Cx. pseudovishnui, and Cx. gelidus. The results of this study may be useful for better planning and implementing a JE control strategy.
Subject(s)
Culex/drug effects , Encephalitis, Japanese/transmission , Insecticides/pharmacology , Animals , DDT/pharmacology , Female , Insecticide Resistance , Malathion/pharmacology , Nitriles/pharmacology , Pyrethrins/pharmacologyABSTRACT
BACKGROUND: In India, sulphadoxine-pyrimethamine (SP) is now in use as a partner drug of ACT (AS+SP) to treat uncomplicated falciparum malaria since 2010. Declined trend of AS+SP efficacy has been reported from north-eastern states of the country. It is not possible to determine the efficacy of SP alone from any study with ACT. So, this work was designed to study the pattern of polymorphisms in pfdhfr and pfdhps genes to predict the SP resistance status among parasite population of urban Kolkata after five years of ACT implementation. METHODS: A total of 125 P. falciparum positive patients were enrolled in the study during December 2014 to July 2016 and treated with AS+SP. Parasitic DNA was isolated and subjected to sequencing of pfdhfr and pfdhps genes directly from purified PCR products. RESULTS: Genotyping of both the genes was successfully done in 113 isolates. In pfdhfr, 94.69% (107/113) isolates showed mutations at codon 59 and 108. A double mutant genotype ANRNI was mostly prevalent (107/113, 94.69%), while wild-type genotype ANCSI was found only in 5.3% (6/113) isolates. In pfdhps, mutations were recorded at codon 436 and 437 in 65.49% (74/113) and 23.01% (26/113) isolates, respectively. In combined pfdhfr-pfdhps genes, triple mutant ANRNI-FAKAA was most prevalent (45/113, 39.82%) followed by double mutant ANRNI-SAKAA (37/113, 32.74%) and quadruple mutant ANRNI-FGKAA (24/113, 21.24%). CONCLUSION: SP resistance hallmark mutations i.e., quadruple (AIRNI-SAEAA) or quintuple (AIRNI-SGEAA) genotype in pfdhfr and pfdhps was absent which indicates that SP components of used ACT is still effective in the study area. It is also evident by the clinical response of AS+SP. Monitoring the efficacy of this combination (both by therapeutic and molecular marker study) at a regular interval is highly suggested to record any development of SP resistance in near future.