Geographic information system-aided evaluation of epidemiological trends of dengue serotypes in West Bengal, India.

BACKGROUND OBJECTIVES: West Bengal is a dengue-endemic State in India, with all four dengue serotypes in co-circulation. The present study was conceived to determine the changing trends of circulating dengue virus (DENV) serotypes in five consecutive years (2015-2019) using a geographic information system (GIS) during the dengue season in West Bengal, India. METHODS: Molecular serotyping of dengue NS1 sero-reactive serum samples from individuals with ≤5 days of fever was performed using conventional nested reverse transcriptase-PCR. GIS techniques such as Getis-Ord Gi* hotspot analysis and heatmap were used to elucidate dengue transmission based on the received NS1-positive cases and vector data analysis was used to point out risk-prone areas. RESULTS: A total of 3915 dengue NS1 sero-positive samples were processed from most parts of West Bengal and among these, 3249 showed RNA positivity. The major circulating serotypes were DENV 3 (63.54%) in 2015, DENV 1 (52.79%) in 2016 and DENV 2 (73.47, 76.04 and 47.15%) in 2017, 2018 and 2019, respectively. Based on the NS1 positivity, dengue infections were higher in males than females and young adults of 21-30 yr were mostly infected. Getis-Ord Gi* hotspot cluster analysis and heatmap indicate that Kolkata has become a hotspot for dengue outbreaks and serotype plotting on maps confirms a changing trend of predominant serotypes during 2015-2019 in West Bengal. INTERPRETATION CONCLUSIONS: Co-circulation of all the four dengue serotypes was observed in this study, but only one serotype became prevalent during an outbreak. Representation of NS1-positive cases and serotype distribution in GIS mapping clearly showed serotypic shift in co-circulation. The findings of this study suggest the need for stringent surveillance in dengue-endemic areas to limit the impact of dengue and implement better vector-control strategies.

Challenges for maintaining post elimination phase of visceral leishmaniasis control programme in India: A field-based study.

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.

Assessment of effectiveness of Japanese encephalitis vaccination in West Bengal, India using sample positivity rate as an alternate measure.

BACKGROUND & OBJECTIVES: Japanese encephalitis (JE), is a vaccine preventable mosquito borne arboviral disease. The State Health Department of West Bengal, India started a vaccination programme using live attenuated, single dose JE vaccine (SA-14-14-2) in children aged 1-below15 years since 2006 in five districts. The objectives were to compare Sample Positivity Rates (SPR) of Acute Encephalitis Syndrome (AES) cases for JE between vaccinated & unvaccinated districts and observe trend of SPR & Cumulative Incidence in vaccinated districts for three years. METHODS: The study was based on the analysis of surveillance data from all tested AES cases including confirmed JE (IgM ELISA) from all JE testing facilities existent in the state during the study period (2011-13). Calculation of Cumulative Incidence, Odds Ratio (OR) with 95% CI, Preventive Fraction and Chi Square for trend (for SPR) was done. Trend of incidence was assessed by linear regression. RESULTS: In three years, 5 vaccinated districts contributed 945 AES and 88 JE cases (SPR - 9.3%) compared to 1807 and 254 (SPR - 14.1%) JE cases in 14 unvaccinated districts. Effectiveness of vaccination was evident by gradual decline of Odds Ratio in favour of vaccinated districts. Vaccination effectiveness of 68% overall and 80% [OR = 0.20 (0.10 - 0.41)] in below 15 years were observed. Trend of SPR was found significantly declining in most of the vaccinated districts. INTERPRETATION & CONCLUSION: Significant reduction in sample positivity rate over three years in most of the vaccinated districts indicated that the vaccination programme had been gradually effective.

Insecticide susceptibility status of Phlebotomus argentipes and polymorphisms in voltage-gated sodium channel (vgsc) gene in Kala-azar endemic areas of West Bengal, India.

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 rate = 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.

Glycoproteins in circulating immune complexes are biomarkers of patients with Indian PKDL: A study from endemic districts of West Bengal, India.

BACKGROUND: Post Kala Azar Dermal Leishmaniasis (PKDL) occurs as dermal consequence of previous Visceral Leishmaniasis (VL) infection and serves as an important reservoir for transmission of VL. Diagnosis of PKDL is often challenging for its symptomatic resemblance to other co-endemic diseases like Leprosy or Vitiligo. Parasitological examination by slit-skin smear and culture are the standard methods but lack high sensitivity. Thus, for efficient control of VL, reliable diagnostic and prognostic assay of PKDL are required. OBJECTIVE: Previously, glycoproteins (9-OAcSA) have been reported as promising biomarkers of Indian VL patients. However, till date, the status of glycans in Indian PKDL patients remains unexplored. Accordingly, in this study, the glyco-profile of PKDL Circulating Immune Complexes (CICs) as compared to other cross diseases like Vitiligo and Leprosyhas been investigated. Further, a novel Glyco CIC assay has been developed for efficient Indian PKDL patient diagnosis. METHODS/PRINCIPAL FINDING: In the present study, 90 PKDL patients were enrolled from 3 VL endemic districts of West Bengal during 2015-16. Glycosylation profile of isolated CICs from sera of PKDL patients were initially analyzed through gradient SDS gel electrophoresis followed by PAS silver double staining, which revealed the presence of several glycan rich PKDL specific proteins of varying molecular weights. To further characterize the glyco-profile of acid dissociated affinity purified immuno-reactive antigens present in the CICs, glycosylation was demonstrated in these purified CIC antigens by DIG glycan differentiation kit with or without glycosidase as well as neuraminidase treatment. Diagnostic evaluation of the newly developed colorimetric Glyco CIC assay through Receiver Operating Characteristic (ROC) curve analysis revealed excellent (0.99) AUC value as compared to other conventional serodiagnostic assays like PEG CIC, Parasite ELISA (IgG and IgM). Additionally, longitudinal monitoring of 18 PKDL patients further revealed its good prognostic utility. CONCLUSION: These results highlight the glycosylation status of CICs among Indian PKDL patients present in all the studied endemic districts of West Bengal. These PKDL biomarkers were completely absent in cross diseases like Vitiligo and Leprosy. Further, the newly developed Glyco CIC assay had an improved sensitivity of 95.6%, specificity of 99.3%, NPV of 97.1% and PPV of 98.9%.

Contaminated pond water favors cholera outbreak at haibatpur village, purba medinipur district, west bengal, India.

Health workers reported an increased number of diarrhea cases at Haibatpur village on June 17, 2012. This outbreak was investigated with the following objectives: to confirm the existence of diarrhea outbreak, to find out the risk factors, and propose control measures. Cases were listed; spot map and epidemic curve were drawn. Attack rate was calculated by age and sex and risk factors were found out by calculating odds ratio (OR) with 95% confidence interval (CI). Rectal swabs were taken and water specimens were collected for laboratory test. Forty-one cases of patients were identified with overall attack rate (AR) was 5% (41/780). AR among men was higher 6% (25/404) than women. There was no death. V. cholerae 01 Eltor Ogawa was isolated from one (1/4) stool specimen. Spot map showed cases clustered around two ponds which were contaminated with coliform organisms. The underground water was a bit saline in nature. Using pond water for preparation of fermented rice (Panta Bhat) (OR 4.73, 95% CI 1.69-13.51), washing utensil in pond water (OR 7.31, 95% CI 1.77-42.29) were associated with cholera outbreak. Health education was done to villagers. Disinfection of two ponds with bleaching powder was done. We proposed supplying of safe drinking water and repairing defective deep tube well to village.

Measles outbreak among the Dukpa tribe of Buxa hills in West Bengal, India: epidemiology and vaccine efficacy.

Although measles is a vaccine preventable disease, its occurrence and outbreaks are common in India. Four remote and inaccessible hamlets, inhabited by the Dukpa tribe, at Buxa Hills under Kalchini Block of Jalpaiguri District, West Bengal experienced a measles outbreak during the months of April-June, 2011. The authors conducted an investigation to assess vaccine coverage, vaccine efficacy (VE) and to describe the patterns of measles outbreaks in this community. The over-all attack rate was 14.3%; that among males and females were 12.6% and 16.0% respectively (P = 0.189). Attack rate was highest (40%) in 0 to <5 years followed by that in the 5 to <15 years (36.5%). VE was 66.3% (95% of the confidence interval 46.9-78.6%). There is an urgent need to increase the vaccination coverage through special tactics for reaching the unreached.

Isolation and characterization of pandemic and nonpandemic strains of Vibrio parahaemolyticus from an outbreak of diarrhea in North 24 Parganas, West Bengal, India.

Strains of the enteric pathogen Vibrio parahaemolyticus harboring the thermostable hemolysin (TDH) encoding gene tdh is known to cause epidemic and pandemic diarrhea. In industrialized countries, this pathogen causes sporadic or outbreaks of diarrheal illness associated with consumption of raw or improperly cooked seafood. This report describes a foodborne outbreak of gastroenteritis caused by V. parahaemolyticus in June 2011 following consumption of food served at a funeral reception held at Habra, North 24 Parganas, West Bengal, India. About 650 people attended the function, of whom 44 had acute watery diarrhea with other clinical symptoms; 35 of them were admitted to the District Hospital for the rehydration treatment. Stool specimens collected from three hospitalized cases were positive for V. parahaemolyticus, of which two strains were identified as an O4:K8 serovar and one was identified as O3:K6 serovar. The O3:K6 strain also possessed the pandemic group-specific toxRS gene target (GS), whereas the O4:K8 strains were negative. All strains were polymerase chain reaction-positive for tdh but were polymerase chain reaction-negative for trh. All of the strains were resistant to ampicillin but were pansensitive to other antimicrobials tested. Pulsed-field gel electrophoresis (PFGE) analysis using NotI showed that the O3:K6 strain was similar to that of a recent clinical strain from Kolkata, but had diverged from other strains during previous years. In contrast, PFGE analysis showed that the O4:K8 strains were closely related but differed from the Kolkata strain.

Visual impairment in urban school children of low-income families in Kolkata, India.

To evaluate pattern of visual impairment in school children from low-income families in Kolkata, India, an institutional cross-sectional study was conducted among 2570 children of 10 primary schools. Ocular examination including refraction was done and pattern of visual impairment and refractive error was studied. The age range was 6-14 years. Refractive error was seen in 14.7%. Only 4 children were already wearing correction. Myopia and hypermetropia was present in 307 (11.9%) and 65 (2.5%) children, respectively. Visual acuity of less than 6/12 in better eye was present in 109 (4.2%) and 5 (0.2%) children pre- and post-correction, respectively. Eighteen children had amblyopia. Although prevalence of refractive error in this group is less compared to school children of all income categories reported from other cities of India, it is more compared to school children of all income categories from the same city. Refractive error mostly remains uncorrected in this group.

The heterogeneity of measles epidemiology in India: implications for improving control measures.

BACKGROUND: Measles vaccination coverage varies in India. Trainees of the Field Epidemiology Training Programme (FETP) investigated 8 outbreaks from 2004 through 2006 in Himachal Pradesh, Uttaranchal, Tamil Nadu, and West Bengal. We reviewed these outbreaks to contribute to the description of the epidemiology of measles and propose recommendations for control. METHODS: FETP trainees searched for measles cases through stimulated passive surveillance or door-to-door case search; estimated attack rates, case fatality, and the median age of case patients; interviewed mothers about vaccination status of their children; and collected serum samples for immunoglobulin M serological testing whenever possible. For 3 outbreaks, the trainees estimated the vaccine efficacy for children >12 months of age through cohort studies. RESULTS: Six of the 8 outbreaks were serologically confirmed. Compared with outbreaks in other states, outbreaks in states with vaccination coverage of >90% had a higher median age among case patients and a lower median attack rate. Six deaths (case fatality rate, 1.5%) occurred during the 5 outbreaks for which vitamin A was not used. The vaccine efficacy was 84% (95% confidence interval [CI], 74%-91%) in Himachal Pradesh. In West Bengal, it was 66% (95% CI, 44%-80%) in 2005 and 81% (95% CI, 67%-89%) in 2006. CONCLUSIONS: In states with higher coverage, attack rates were lower and case patients were older. Although states with coverage of <90% should increase 1-dose coverage and address coverage in pockets that are poorly reached, a second opportunity for measles vaccination could be considered in states such as Himachal Pradesh and Tamil Nadu. Use of vitamin A for case management needs to be generalized.

Strategies to improve the performance of female health workers in West Bengal: a cross-sectional survey.

BACKGROUND: Female health workers in India face an increasing workload that affects their performance. We did a study in 2 districts of West Bengal, India, to quantify their workload and identify determinants of good performance. METHODS: We randomly sampled female health workers from the health department's list. First, we quantified the time allocated to tasks through observations of work sessions. Second, we estimated the prevalence ratio (PR) of above-average performance for three indicators (DPT-booster coverage, antenatal check-up coverage and family planning performance) according to selected potential determinants. RESULTS: Female health workers spent 26% of their time in documentation. We recruited 42 female health workers (average population covered: 6495). Larger floor space (PR 2.5; 95% CI 1.2-5.3), use of simplified documentation procedures (PR 2.5; 95% CI 1.2-5.2) and monthly supervision (PR 3.0; 95% CI 1.1-8.5) were associated with above-average DPT-booster coverage. Availability of a private space was associated with above-average coverage in antenatal check-up (PR 1.9; 95% CI 1.0-3.5) and family planning (PR 2.5; 95% CI 1.2-5.2). Workers who used existing resources to cope with multi-tasking performed better. CONCLUSION: Female health workers spent excessive time in documentation which left less time for service delivery. Infrastructure, planning and supervision affected performance and these areas must be strengthened to improve primary healthcare services.

Prospective randomized comparative study of macular thickness following phacoemulsification and manual small incision cataract surgery.

PURPOSE: To compare macular thickness following uncomplicated phacoemulsification with foldable acrylic lens and manual small incision cataract surgery (MSICS) with non-foldable polymethyl methacrylate (PMMA) lens implantation. METHODS: Prospective study was carried out with one eye each of 224 patients with senile cataract randomized into two groups, phacoemulsification and MSICS, by simple 1:1 randomization. Following surgery by either of the two methods, macular thickness was measured by optical coherence tomography (OCT) on the 1st, 7th, 42nd and 180th postoperative day. Main outcome measure was postoperative macular thickness. RESULTS: On the first postoperative day, central subfield mean thickness (CSMT) in MSICS group was 192.8 +/- 17.9 microm and that in phacoemulsification group was 192.1 +/- 27.4 microm, with no significant difference (p = 0.12). On the 7th day, CSMT in MSICS group (198.9 +/- 21.4 microm) was significantly (p = 0.04) more than that in phacoemulsification group (193.1 +/- 19.3 microm). On the 42nd day, CSMT in MSICS group was 207.8 +/- 26.3 microm and that in phacoemulsification group was 198.3 +/- 23 microm, the difference being significant (p = 0.007). Clinically macular oedema was not diagnosed in any of the patients at any visit. The increase in macular thickness was sub-clinical and did not affect final visual outcome in any patient. CONCLUSION: In spite of the greater theoretical risk of increased postoperative inflammation following MSICS, there was no evidence of cystoid macular oedema, either clinically or on OCT. However, chance of sub-clinical increase in CSMT was more following MSICS compared to phacoemulsification.

An observational study of the pattern of HIV infection in a specified rural area of India with special reference to migratory laborers.

OBJECTIVE: Determination of the pattern of HIV/AIDS in patients attending voluntary confidential counseling and testing center (VCCTC) and prevention of parent-to-child transmission (PPTCT) center of a low-prevalence district of Eastern India. To find out high-risk group and interventional strategy for prevention. METHOD: Cross-sectional exploratory secondary data analysis from the VCCTC and PPTCT register. RESULT: Of the 1348 participants, 160 (11.86%) adults were HIV seropositive. Prevalence in males and females was 9.8% and 20.7%, respectively. Among 22 (1.63%) seropositive children, transmission was vertical in 18 (81.8%). Seventy-one (88.75%) positive adult males were migratory goldsmiths working in Mumbai and other big cities. They were clustered in a particular locality (Daspur). CONCLUSION: Goldsmiths migrated from Daspur to big cities are the bridge populations who are responsible for higher prevalence of HIV in their families and locality. Interventional strategies targeted at this high-risk group are suggested.

Evaluation of registered visually disabled individuals in a district of west bengal, India.

OBJECTIVE: To identify the sociodemographic characteristics, degree and cause of visual disability among certified visually disabled individuals in a rural district of West Bengal, India and to identify possible lacunae, if any, in the existing certification system. MATERIALS AND METHODS: A cross-sectional study by secondary data analysis of medical records of 155 visually disabled individuals and their 310 eyes. Demographical features, diagnosis, percentage of visual disability and work activity status of each individual were analyzed. RESULTS: One hundred and thirty one (84.52%) individuals had 100% disability. The number of males was significantly higher than that of females. Fifty eight (37.42%) individuals were below 21 years of age. Phthisis bulbi was the most common cause followed by microphthalmos. Further, 81.29% patients had the same lesion bilaterally. CONCLUSION: Patients with higher grades of disability have attended certification boards. A large number of disabled individuals comprised children and young adults. Male gender bias demands concern.