Lyme Borreliosis, a public health concern in India: Findings of Borrelia burgdorferi serosurvey from two states.

Background: Lyme borreliosis is a public health concern in India. The prevalence of the disease is still undetermined with major entomological and epidemiological gaps. The present study was conducted to determine the seropositivity of Borrelia burgdorferi in Sikkim and Arunachal Pradesh, India. Methods: A cross-sectional serosurvey was conducted in Sikkim and Arunachal Pradesh. Data collection tools were developed and standardized for the collection of clinico-socio-demographic data. Sample size for each site was calculated using the formula for the estimation of a single proportion. Qualitative detection of IgG antibodies in serum samples was done using NovaLisa™ Lyme Borrelia IgG ELISA kit. Results: A total of 793 participants were enrolled, 484 (61%) from Arunachal Pradesh and 309 (39%) from Sikkim. Out of 793 participants, 21 (2.7%), 22 (2.8%), 6 (0.8%), 29 (3.7%), 44 (5.5%), and 16 (2.1%) gave history of tick bite, rash, erythema migrans, migratory muscle pain, migratory joint pain, and numbness, respectively, in the past one year. The adjusted seroprevalence (for sensitivity and specificity of kit) for the study is 3.7 (2.4-5.2). No signs or symptoms were found to be associated with IgG ELISA positivity. The state-wise distribution of seropositivity for Arunachal Pradesh and Sikkim was 4.1 (95% CI: 2.5-6.3) and 2.3 (95% CI: 0.9-4.6), respectively. Conclusion: This study establishes the state of Sikkim as a new endemic area in India of Lyme disease besides its already reported endemicity in Arunachal Pradesh. No association was conclusively established between symptoms of Lyme and IgG seropositivity emphasizing the need for detailed history taking and clinical suspicion in endemic areas.

Novel pyriproxyfen based treatment for Aedes breeding control through a long-lasting formulation: Laboratory and field trials in Western Maharashtra, India.

BACKGROUND & OBJECTIVES: There is a need to evaluate novel techniques for dengue control in India. Several formulations of pyriproxyfen have been assessed for efficacy and duration of action. Pyriproxyfen is also used as a microencapsulated ready-to-use formulation against the Aedes vector. We evaluated a novel pyriproxyfen-based microencapsulated formulation. This slow-release, ready-to-use aqueous spray is a larvicidal formulation, and we assessed its efficacy and residual action through laboratory and semi-field trials against Aedes immature stages. METHODS: The study was carried out as per the guidelines for laboratory and field/small-scale field testing of mosquito larvicides by the World Health Organization. The evaluation was conducted in laboratory and semi-field conditions from August to December 2018. We tested the novel formulation on three materials (plastic, ceramic, and enamel) in the laboratory for its action as an antilarval. Four containers of each kind were sprayed with the formulation and kept as replicates. Four controls were used in the laboratory trials - 120 larvae (third instar) were introduced in the replicates and the controls each. Readings were taken daily till complete adult emergence or larval and pupal mortality. In the semi-field trials, we applied this formulation to the inside of desert coolers and observed larvicidal and pupicidal activity over five months. Data is presented in numbers and percentages, along with mean and standard deviation. Adult emergence and Emergence Inhibition was calculated. RESULTS: There was 100% adult emergence inhibition amongst the exposed larvae in the treated containers in the laboratory trials. In the untreated controls, adult emergence ranged from 80-95% in all types of containers. In the semifield trials, Inhibition Emergence was 100% in the treated desert coolers during the five months of the study period. INTERPRETATION & CONCLUSION: This advancement in insecticide formulation technology promises to make dengue control more effective and efficient.

Outbreak prone communicable diseases of public health importance in the northern districts of West Bengal - Current status & the way forward.

India is perilously poised on the threshold of an explosion of infectious diseases, some of which have witnessed re-emergence while others await apposite opportunity to do so. The State of West Bengal is uniquely positioned with its innate geographical vulnerabilities that favour outbreaks of a host of infectious diseases. The northern districts of this State are well known endemic areas for many outbreak prone communicable diseases like malaria, Japanese encephalitis, scrub typhus, dengue and kala-azar. An outbreak of Nipah virus in the recent past is a pointer towards the emerging and re-emerging threat in these regions and warrants urgent prioritization for surveillance and monitoring of these diseases. Identification of risk factors, challenges in delivery of primary healthcare, implementation of intervention strategies along with strengthening of healthcare setup are also the need of the hour. Multisectoral initiatives with emphasis on understanding the complex and rapidly evolving human-animal-vector dynamics as envisaged under the 'One Health' concept are indubitably important pillars in the effective management of these emerging public health challenges.

Evaluation of bioactivity of aqueous extracts of Bougainvillea spectabilis, Saraca asoca, and Chenopodium album against immature forms of Aedes aegypti.

BACKGROUND: Increasing rate of vector transmission of dengue has led to the exponential rise in the mortality and morbidity scales in the past five years. There are various natural and synthetic chemical agents available commercially as potent larvicides, but they are either highly toxic, difficult to obtain, have a high manufacturing cost, or show cross-resistance, hence do not suffice as ideal larvicides. The objective was to screen aqueous extracts of Bougainvillea spectabilis (B. spectabilis), Saraca asoca (S.asoca), and Chenopodium album (C. album) for larvicidal activity against Aedes aegypti (A. aegypti). METHODS: The larvae were exposed to increasing concentrations of aqueous extracts of B. spectabilis, S. asoca, and C. album under controlled laboratory environment. The mortality was checked after 24 hours, results were statistically analyzed, and LC50 and LC90 were determined. RESULTS: B. spectabilis and S. asoca were found effective as larvicides against A. aegypti with LC50 values of 0.22% and 0.26%, respectively. CONCLUSION: The aqueous extracts of B . spectabilis and S. asoca are efficient larvicides against A . aegypti and can be used as effective, accessible, and eco-friendly control options for management of A. aegypti, the vector of dengue/chikungunya.

Scrub typhus strikes back: Are we ready?

Scrub typhus has struck back, albeit with renewed vigour, impacting areas with previously known endemicity as also impressing newer expanses. It is not surprising, therefore, that Scrub typhus has emerged as a leading cause of public health concern globally as well as in India, but are we ready to take on the challenge? Over the last decade, there has been a global increase in the number of outbreaks of Scrub typhus, be it the military occupied areas or the civil population at large. The innumerable outbreaks of Scrub typhus, although disconcerting, have nonetheless contributed phenomenally towards better understanding of the dynamics of scrub typhus. There have been significant contributions to awareness of the disease amongst medical professionals, scrub typhus as a cause of Acute Undifferentiated Febrile Illness (AUFI) and newer clinical manifestation - Acute Encephalitis Syndrome (AES), availability and advances in diagnostics and management, man-vector-pathogen interactions, new records of Leptotrombidium species, newer vectors and Orientia species. Antigenic diversity and the varied clinical presentation of scrub typhus, absence of scrub typhus surveillance system and a lack of political will to recognize the disease as one of the important reemerging public health problem are areas seeking concerted deliberations and actions so that the challenges posed by scrub typhus can be addressed.

Bio-eco-social determinants of Aedes breeding in field practice area of a medical college in Pune, Maharashtra.

BACKGROUND: Major determinant of dengue incidence is interaction between ecology, vector bionomics, and social factors. OBJECTIVES: The objective of the study is to find out bio-eco-social determinants of Aedes breeding. METHODS: Background, household, entomological, and knowledge, attitude, and practice (KAP) surveys were undertaken post- and premonsoon showers from May to June 2016 in urban and rural practice area of medical college. RESULTS: A total of 181 and 204 households, 131 and 137 individuals, and 1250 and 1268 water-holding containers were included in household survey, KAP survey, and larval survey in urban slum and rural area, respectively. In both locations, maximum water-holding containers were indoors (41.4% and 61.8%, respectively); however, maximum positivity was peridomestic (63.6% and 83.1%, respectively). Pupae per container were 0.9 and 1.9 in respective locations and pupae per person were 1.2 and 2.3, respectively. Container positivity was seen in containers with rain as water source (8.8%) as well as among those who were never used (10.7%). Irregular water supply was significantly more in rural area (P < 0.05). KAP survey revealed that majority (90.1% and 71.5%, respectively) had heard about dengue, with significantly higher knowledge in urban slum, and television was the main source of information. Majority (89% and 83%, respectively) were unaware that peak biting time of Aedes is daytime. Use of mosquito repellent coils was the predominant preventive practice (46.6% and 61.2%, respectively). Pupae were reared; all were found to be Aedes aegypti. CONCLUSIONS: Despite enhanced awareness campaigns, an integrated vector management approach is required for prevention of dengue.

Zoonotic surveillance for rickettsiae in rodents and mapping of vectors of rickettsial diseases in India: A multi-centric study.

BACKGROUND: The global resurgence of rickettsial diseases and their potential to impact the fitness of military personnel and inflict widespread casualties amongst civil populations has emerged as a major cause of public health concern. Absence of surveillance system, lack of awareness amongst medical fraternity to rickettsial activity along with the difficulty in diagnosis because of their protean clinical manifestations are reasons for the outbreaks of these diseases. OBJECTIVES: To determine rickettsial activity amongst rodents and study vector diversity, abundance and their distribution to enable mapping of rickettsial hotspots. METHODS: Zoonotic surveillance was undertaken in six selected study areas in India - Jammu, Akhnoor, Rajouri-Poonch, Udhampur-Nagrota, Dehradun and Pune. Weil-Felix test was used for rickettsial sero-surveillance amongst rodents and standard identification keys were used for mapping vector diversity and database preparation. RESULTS: Serological findings revealed positivity to all the three rickettsial antigens (OXK, OX19 and OX2) in Jammu, OX19 in Dehradun and OXK and OX2 positivity in Udhampur-Nagrota belt. The vector database records presence of 16 species of trombiculid mites from three important genera - Leptotrombidium, Schoengastiella and Gahrliepia with ticks from five genera and 8 species of fleas from four genera. Mite fauna of study sites has been enriched with addition of new records of mite species (five mite species at Pune, two at Akhnoor with one mite species each at Jammu and Dehradun). CONCLUSION: The study reveals rickettsial activity amongst rodents at Jammu, Dehradun and Udhampur-Nagrota belt. The results correlate well with the presence of vectors of scrub and tick typhus and corroborate the occurrence of outbreaks of these diseases in the respective areas.

Dengue, chikungunya and the missing entity - Zika fever: A new emerging threat.

Zika virus (ZIKV), a relative newcomer from the flavivirus group that includes dengue, Japanese encepahalitis and yellow fever, is one of the emerging pathogens that is fast transcending geographical boundaries. It is a vector-borne disease transmitted by the same Aedes aegypti and Aedes albopictus, which cause dengue and chikungunya. In addition to the vector-mediated transmission of Zika fever, probable human-to-human transmission through exchange of body fluids, including sexual and perinatal transmission and through blood transfusion, makes containment of this new entity more challenging. Moreover, a high index of suspicion by an astute physician is necessary for diagnosis of Zika fever in view of the similarity of symptoms with dengue and chikungunya, especially in areas, where these two diseases are already endemic. Zika, till recently, has had minimal impact, but its true potential is unfolding with increasing detection of congenital malformities, Guillain-Barré syndrome and other neurological and autoimmune syndromes in patients with recent history of ZIKV infection, or when mothers get infected with Zika during first or second trimester of pregnancy. The association, however, needs to be established, nonetheless it is important that we keep a close vigil on this emerging vector borne disease - the 'ZIKA' fever.

Emergence of Schoengastiella ligula as the vector of scrub typhus outbreak in Darjeeling: has Leptotrombidium deliense been replaced?

BACKGROUND: Following a suspected outbreak of scrub typhus in Kurseong, Darjeeling, the Armed Forces Medical College, Pune was requested by the National Institute of Epidemiology and the State authorities to undertake investigation of the ongoing scrub typhus outbreak and suggest containment measures. MATERIALS AND METHODS: The epidemic team undertook clinical, entomological and serological studies to understand the local disease pattern and delineate high risk areas, host diversity by rodent trapping using Sherman traps, mite fauna diversity, abundance and vector species identification by phase contrast microscopy for preparation of electronic database and rodent and human serological studies by Weil Felix and PCR. RESULTS: The results indicate no association of scrub typhus with age and sex (P=0.37 and 0.74 respectively). The maximum cases occurred amongst the tea garden workers (73%) in the age group of 25-44 years. The predominant clinical presentation was fever (100%) with headache (75%), lymphadenopathy (45%) and presence of eschar (76.7%). The dominant host species (50% of trapped rodents) was shrew Suncus murinus, the index animal for scrub typhus, which contributed maximally to the vector abundance (52.96%) with a chigger index of 61.56. The trombiculid mite Schoengastiella ligula was the vector species much against the expected mite vector Leptotrombidium deliense, in the area. The study found the presence and abundance of vector species which corroborated well with the occurrence of cases in the various localities within the subdivisions. CONCLUSION: The study thus establishes Schoengastiella ligula as the vector of scrub typhus outbreak in Kurseong, Darjeeling. Preventive and containment measures with emphasis on reduction of man - vector contact were suggested to the state authorities to contain the outbreak.

Effectiveness of Diflubenzuron in the control of houseflies.

BACKGROUND & OBJECTIVES: Houseflies are one of the major pest problems worldwide. The current housefly control strategy in the country hinges on the use of Dichlorvos as a housefly larvicide and pyrethrum spray in kitchens/dining areas. The present study was undertaken to evaluate the newer housefly control options in the wake of concerns about human toxicity of Dichlorvos and its continued use in public health. METHODS: Efficacy of Diflubenzuron WP and granule formulations (chitin synthesis inhibitor) vis-à-vis Dichlorvos EC in the control of housefly was assessed in laboratory by adult emergence inhibition after treatment and in field conditions by estimation of density post-application up to three weeks using standard methods. RESULTS: Dichlorvos EC and Diflubenzuron formulations (WP and granule) brought about 100% inhibition of adult emergence under laboratory conditions. However, in the field evaluation, effective suppression of housefly population was brought about by Dichlorvos and Diflubenzuron granule formulation (though delayed). CONCLUSION: Dichlorvos EC and Diflubenzuron granule formulation are effective housefly larvicides. It is recommended that Diflubenzuron WP formulation be evaluated at a higher frequency to enhance its effectiveness and its use may be considered in conjunction with an initial suppression of housefly adults with an adulticide, e.g. Cyphenothrin, etc.

Insecticide treated bednet strategy in rural settings: can we exploit women's decision making power?

Use of insecticide treated bednets in prevention of malaria is a widely propagated global strategy, however, its use has been reported to be influenced and limited by many variables especially gender bias. A cross sectional field epidemiological study was conducted in a rural setting with two outcome variables, 'Bednet use'(primary outcome variable) and 'Women's Decision Making Power' which were studied in reference to various predictor variables. Analysis reveals a significant effect on the primary outcome variable 'Bednet use' of the predictor variables- age, occupation, bednet purchase decision, women's decision making power, husband's education and knowledge about malaria and its prevention. The study recommends IEC on treated bednets to be disseminated through TV targeting the elderly women who have better decision making power and mobilizing younger women who were found to prefer bednets for prevention of mosquito bites for optimizing the use of treated bednets in similar settings.

Field performance of imidacloprid gel bait against German cockroaches (Dictyoptera: Blatellidae).

BACKGROUND AND OBJECTIVES: Resistance amongst cockroaches has been reported to most of the spray insecticides. Imidacloprid gel baits, which can be selectively applied at the infested and potential harborages sites have been found effective in control of cockroach infestation in some laboratory studies but very few field studies are available. This study was therefore undertaken to evaluate the efficacy of imidacloprid gel bait in the control of German cockroaches (Blatella germanica) in field. METHODS: A survey was done to find out pre-treatment density in 12 cookhouses by visual count and sticky trap method. A total of four cookhouses having high cockroach infestation were selected by simple random sampling method (two for imidacloprid treatment and two for control). Imidacloprid gel (2.15%) was used as crack and crevices treatment at the infested sites and potential harborages once only during the entire study duration. Post-treatment density was assessed by visual count method every week for nine weeks. RESULTS: Visual count method gave better indications of cockroach infestation as compared to sticky trap method, hence the same was followed for post-treatment evaluation. Reduction of 75.0 - 86.5 per cent was achieved with imidacloprid gel treatment by week 1 post-treatment in comparison to control areas. The reduction in treated areas by 8 wk post-treatment was 96.3-98.8 per cent in comparison to control areas. Residual effect of imidacloprid started declining at 9 wk (91.7 - 96.5% reduction in comparison to control areas). INTERPRETATION AND CONCLUSION: The results of our study report the efficacy of imidacloprid gel bait (2.15%) up to 8 wk against German cockroaches. The gel was safe and environment friendly also.

Efficacy of synthetic pyrethroid and propoxur aerosol in the control of German cockroaches (Dictyoptera: Blatellidae) in cookhouses.

BACKGROUND AND OBJECTIVES: A field trial was carried out in cookhouses in an urban area to evaluate the efficacy of synthetic pyrethroid (0.02% deltamethrin + 0.13% allethrin) and propoxur aerosols (2%) in the control of German cockroaches (Blatella germanica). METHODS: A total of six cookhouses were selected by simple random sampling method (two each for the two insecticide treatments and two for control). RESULTS: It was observed that 89.36-87.8 and 77.95-59.74% reductions were achieved with propoxur and synthetic pyrethroid treatment respectively by first week post-treatment. The reduction in propoxur treated areas by eight weeks post-treatment was 82.98-76.13%, whereas the reduction in the same time period in synthetic pyrethroid treated areas ranged from 14.36% to an increase in density by a phenomenal 157.86% in one of the treated sites. INTERPRETATION AND CONCLUSION: The study reports the efficacy of propoxur aerosol (2%) treatment over synthetic pyrethroid (0.02% deltamethrin + 0.13% allethrin) in the control of cockroach infestation in cookhouses in urban area.

Field performance of cyphenothrin: an integrated insecticide strategy against German cockroaches (Dictyoptera: Blatellidae).

BACKGROUND & OBJECTIVES: Resistance to organophosphorous and carbamate insecticides amongst German cockroaches is widely reported. Cyphenothrin EC, a new synthetic pyrethroid was evaluated in cookhouses in an urban area, with the aim of exploring alternate control option against the German cockroach Blatella germanica. METHODS: Three cookhouses were selected by simple random sampling method, two for treatment and one as control. The impact of treatment on cockroach infestation was monitored weekly by visual assessment sampling technique. RESULTS: Cyphenothrin brought about 95 to 97.5% reduction in cockroach infestation by the end of six weeks post-treatment. INTERPRETATION & CONCLUSION: The study reports the efficacy of cyphenothrin in the control of German cockroaches and recommends an "Integrated insecticide strategy" for the control of cockroaches in urban cookhouses.

A Laboratory Investigation into Oviposition Responses of Aedes aegypti to Some Common Household Substances and Water from Conspecific Larvae.

BACKGROUND: The surveillance of Dengue vector - Aedes aegypti, is routinely done by using ovitraps (a dark container filled with water and a wooden paddle/towel cloth provided as a oviposition substrate), which indicates the extent of Aedes activity in an area. METHOD: The study evaluated the oviposition responses of laboratory bred gravid Aedes aegypti to commonly available household substances by use of ovitrap method. RESULTS: Oviposition avoidance or deterrence was exhibited by gravid Aedes to ovitraps baited with salt, fenugreek, vinegar, lime juice, hibiscus leaves, radish and curry leaves, whereas positive oviposition response was noticed to waters from conspecific (of the same species) larvae and cumin seeds baited ovitraps. CONCLUSION: The study findings may be utilized by researchers for further chemical analysis of the active ingredients of the substances found promising with a view to explore the possibility of their use by community and individuals for Aedes surveillance and control.

Surveillance of Scrub Typhus in the fringe areas around Pune : Potential for Transmission does exist.

A field based epidemiological study was undertaken to assess the potential of transmission of scrub typhus in the sylvatic and transitional (fringe) areas at ten different locations around Pune. Parameters studied included rodent trapping and identification, entomological parameters, immunological studies on rodent sera, and rodent organ impression smears. The study revealed that Rattus r rufescence, Rattus meltada, Suncus murinus and Rattus blanfordi were the predominant sylvatic rodent species. All the species showed mild to moderate infestation with trombiculid mite larvae, with Rr rufescence and S murinus showing even higher levels of infestation. Pooled rodent sera showed mild rise of OX2 in 13.9%, OX19 in 5.6% and OXK in 9.8% of the pooled sera. The rise in titres was appreciable among rodents from Lonavala, Khadakvasla, Panchet, Singhgadh and Kondhwa areas. Based on the findings of the study, certain recommendations on prevention, surveillance and epidemic investigations of scrub typhus in the Armed Forces have been submitted.

Efficacy of Fipronil and Propoxur in the control of German cockroaches (Dictyoptera: Blatellidae).

A field trial for comparative evaluation of chemicals Fipronil gel, Propoxur spray and bait was carried out. The results in the Fipronil treated area indicate a reduction of 89%, 100% and 98% in cockroach infestation by days 7, 30 and 60, whereas the reduction in Propoxur spray treated area during the same period was 88%, 91% and 87% respectively. Propoxur bait was not found to be effective in reducing the cockroach infestation; rather a build up of the cockroach infestation was noticed in the treated site. The study reports the efficacy of Fipronil gel treatment over conventional insecticidal formulations in the control of cockroach infestation in cookhouses of urban households.