Seroprevalence of dengue virus infection in Pune City in India, 2019: A decadal change

BACKGROUND

The burden of dengue infection needs to be monitored along with tracking of the changes in dengue virus (DENV) transmission intensity for vaccine introduction decisions.

METHODS

The seroprevalence of dengue was investigated in Pune City in India, in early 2019 using 1654 sera from apparently healthy human participants enrolled randomly through multistage cluster sampling. We used 797 retrospective human sera from late 2009 for comparison. All sera were assessed for the presence of dengue-specific IgG antibodies. A subset (n = 230) was tested for serotype-specific plaque reduction-neutralizing antibodies against all four serotypes.

RESULTS

The dengue IgG seroprevalence of 62.9% (95% CI 59.4-66.1) in 2009 increased to 88.4% (95% CI 86.8-89.8) in 2019. Age-stratified dengue seroprevalence revealed a gradual increase in IgG seropositivity from 70.1% in 0-9 years to 85.0% in 10-19 years. The annual probability of dengue infection estimated as a force of infection was 4.1 (95% CI 3.8-4.5) in 2009, which increased to 10.9 (95% CI 10.2-11.6) in 2019. Analysis of dengue serotype-specific neutralizing antibodies revealed DENV-3 as the dominant serotype. The age of exposure to at least one dengue serotype was reduced in 2019 over 2009.

CONCLUSIONS

There was a significant increase in the intensity of dengue virus transmission in Pune City over the decade. Since over 85% of the participants above nine years of age had exposure to DENV by 2019, dengue vaccine introduction can be considered. Moreover, such repeated serosurveys in different regions might inform about the readiness of the population for dengue vaccination.

Comparison of Clinical Profile and Outcomes of Japanese Encephalitis and Acute Encephalitis Syndrome among Rural Children

The study compared the clinical profile and outcomes of Japanese encephalitis (JE) and acute encephalitis syndrome (AES) in children. Fifty-six consecutive children with symptoms fulfilling the WHO clinical case definition of AES from June 2018 to June 2020 were included in the study. All patients who tested positive for either serum or cerebrospinal fluid (CSF) anti-JE-IgM antibodies were JE patients (n = 24) and compared with non-JE AES cases (n = 32). Fever, seizures, and altered sensorium were the most common presenting symptoms. Low GCS, status epilepticus, meningeal irritation, raised CSF protein, and INR > 1.5 of JE children showed significant association with mortality (p value < 0.05), whereas only low GCS showed significant association in non-JE AES cases. The JE-specific mortality rate was 29%, which was less than the mortality rate of non-JE AES children at 41%. Both JE and non-JE AES children had a similar clinical profile, but only the JE children's poor clinical and laboratory parameters were associated with adverse outcomes.

Infectious Causes of Acute Encephalitis Syndrome in India - Decadal Change and the Way Forward

The diagnosis and management of encephalitis were previously largely based on clinical grounds and minimal laboratory investigations. Japanese encephalitis (JE) gets considered as the probable diagnosis in most encephalitis cases. However, reports of JE in adults and the elderly are increasing after the JE vaccine introduction among children in 2006. The Nipah virus (NiV) emerged in 2002 and continues to afflict humans in new geographic areas. Many other infections cause encephalitis, including Chandipura, chikungunya, dengue, and West Nile. Significant advances in diagnostic testing like multiplex testing panels and metagenomic approaches along with sequencing have helped in the detection of new etiologies. Recent years have witnessed an increase in climate-sensitive zoonotic diseases with encephalitis. This highlights the importance of the One Health approach in studying the impact of climate change-associated infectious diseases on human health. The government of India's efforts to develop health research infrastructure would help future responses to emerging infectious disease epidemics.

Incidence of Japanese Encephalitis and Acute Encephalitis Syndrome Hospitalizations in the Medium-Endemic Region in Central India

BACKGROUND

We estimated the incidence of Japanese encephalitis (JE) and acute encephalitis syndrome (AES) following routine immunization with the live-attenuated SA 14-14-2 JE vaccine.

METHODS

We implemented enhanced surveillance of AES and JE hospitalizations in endemic districts in Maharashtra and Telangana States during 2015-2016 and 2018-2020. We estimated incidence and compared differences in the incidence of JE and AES between two states, and vaccinated and unvaccinated districts during two study periods. We also considered secondary data from public health services to understand long-term trends from 2007 to 2020.

RESULTS

The annual AES incidence rate of 2.25 cases per 100,000 children in Maharashtra during 2018-2020 was significantly lower than 3.36 cases per 100,000 children during 2015-2016. The six JE-vaccinated districts in Maharashtra had significantly lower incidence rates during 2018-2020 (2.03, 95% CI 1.73-2.37) than in 2015-16 (3.26, 2.86-3.70). In addition, the incidence of both JE and AES in two unvaccinated districts was higher than in the vaccinated districts in Maharashtra. Telangana had a lower incidence of both JE and AES than Maharashtra. The AES incidence rate of 0.95 (0.77-1.17) during 2018-2020 in Telangana was significantly lower than 1.67 (1.41-1.97) during 2015-2016.

CONCLUSIONS

The annual incidence rate of Japanese encephalitis was < 1 case per 100,000 children. It indicated accelerated control of Japanese encephalitis after routine immunization. However, the annual incidence of acute encephalitis syndrome was still > 1 case per 100,000 children. It highlights the need for improving surveillance and evaluating the impacts of vaccination.

Effectiveness of Japanese encephalitis vaccination among children in central India

Japanese encephalitis (JE) disease among children continues in central India despite vaccination implemented in the routine immunization program. Therefore, we planned to estimate the JE vaccination effectiveness among children by undertaking a 1:2 individually-matched population-based case-control study from August 2018 to October 2020. The laboratory-confirmed JE cases aged 1-15 years were enrolled along with neighborhood controls without fever and encephalitis matched on the residence area, age and sex. The JE vaccination history was enquired from parents and verified independently from the vaccination cards available at home and records at health facilities. We enrolled 35 JE cases and 70 matched controls. The vaccination effectiveness of 86.7% (95% confidence interval [CI]: 30.8-94.7) was estimated on the per-protocol analysis of 31 case-control sets. The screening method provided an effectiveness of 89.5% (CI: 78.9-94.7) on using the population vaccination coverage of 90% reported earlier in the same area. In conclusion, JE vaccination offered a moderate level of protection among children in JE medium-endemic central India, similar to reports from high-endemic areas in India. The operational aspects of vaccination program implementation need to be evaluated to assess the impact of vaccination on the disease burden of JE in medium-endemic regions of India.

Evaluating the effect of measles and rubella mass vaccination campaigns on seroprevalence in India: a before-and-after cross-sectional household serosurvey in four districts, 2018-2020

Background

India did phased measles–rubella supplementary immunisation activities (MR-SIAs; ie, mass-immunisation campaigns) targeting children aged 9 months to less than 15 years. We estimated measles–rubella seroprevalence before and after the MR-SIAs to quantify the effect on population immunity and identify remaining immunity gaps.

Methods

Between March 9, 2018 and March 19, 2020 we did community-based, cross-sectional serosurveys in four districts in India before and after MR-SIAs. 30 villages or wards were selected within each district, and one census enumeration block from each was selected as the survey cluster. Households were enumerated and 13 children in the younger age group (9 months to <5 years) and 13 children in the older ager group (5 to <15 years) were randomly selected by use of computer-generated random numbers. Serum samples were tested for IgG antibodies to measles and rubella viruses by enzyme immunoassay.

Findings

Specimens were collected from 2570 children before the MR-SIA and from 2619 children afterwards. The weighted MR-SIA coverage ranged from 73·7% to 90·5% in younger children and from 73·6% to 93·6% in older children. Before the MR-SIA, district-level measles seroprevalence was between 80·7% and 88·5% among younger children in all districts, and between 63·4% and 84·5% among older children. After the MR-SIA, measles seroprevalence among younger children increased to more than 90% (range 91·5 to 96·0) in all districts except Kanpur Nagar, in which it remained unchanged 80·4%. Among older children, measles seroprevalence increased to more than 90·0% (range 93·7% to 96·5%) in all districts except Hoshiarpur (88·7%). A significant increase in rubella seroprevalence was observed in all districts in both age groups, with the largest effect in Dibrugarh, where rubella seroprevalence increased from 10·6% to 96·5% among younger children.

Interpretation

Measles–rubella seroprevalence increased substantially after the MR-SIAs but the serosurvey also identified remaining gaps in population immunity.

Funding

The Bill & Melinda Gates Foundation and Indian Council of Medical Research.

Coverage of Japanese encephalitis routine vaccination among children in Central India

BACKGROUND

We aimed to estimate the coverage of Japanese encephalitis (JE) vaccination in central India to help explain the continued occurrence of JE disease despite routine vaccination.

METHODS

We implemented a 30-cluster survey for estimating the coverage of JE vaccination in the medium-endemic areas implemented with JE vaccination in central India. The parents were enquired about the uptake of the JE vaccine by their children aged 2 to 6 years, followed by verification of the immunization cards at home along with reasons for non-vaccination. Vaccination coverage was reported as a percentage with 95% confidence intervals.

RESULTS

We estimated high coverage of live-attenuated SA 14-14-2 JE vaccination in Maharashtra (94.8%, 95% CI 92.7-96.3) and Telangana (92.8%, 90.0-94.9). The vaccination card retention was 90.3% in Maharashtra and 70.4% in Telangana state. There were no gender differences in coverage in both states. A similar level of JE vaccination coverage was observed during the year 2013 to 2021 in both states. In Maharashtra, the maximum age-wise coverage was 96.6% in the >60 months age category, whereas in Telangana it was in the <24 months age category (97.2%). The timeliness of JE vaccination was appropriate and similar in both states. We found very good agreement between JE and Measles-Rubella vaccinations administered simultaneously. The reasons for non-vaccination were the shortage of vaccines and the parental migration for work.

CONCLUSIONS

The coverage of Japanese encephalitis vaccination was high in medium-endemic regions in central India. Vaccination effectiveness studies may help further explain the continued incidence of Japanese encephalitis. This article is protected by copyright. All rights reserved.

Outbreak of cholera in a remote village in western India

Background & objectives

Atypical El Tor strains of Vibrio cholerae are frequently implicated in outbreaks of cholera. It is important to understand genetic variations of such strains which impact clinical and epidemiological outcomes. The present study was carried out to characterize an outbreak of cholera which occurred between July 8 and 13, 2018, in a remote settlement in Nashik district, Maharashtra.

Methods

A large number of acute diarrhoea cases were reported in Rahude village, Nashik, Maharashtra since July 8, 2018. Molecular characterization of the isolated strains of V. cholerae was done.

Results

195 cases of cholera were detected from a population of 850 (attack rate 22.9%) with two deaths (Case Fatality Ratio of 1.03). A non-haemolytic polymyxin B sensitive strain of V. cholerae O1 Ogawa was isolated from 5/14 fecal samples. Molecular characterization of the isolates indicated that this strain was an altered El Tor (AET) strain. Deletion of the trinucleotide 'GTA' in the rstB gene, a unique feature of classical strains, was observed.

Interpretation & conclusions

A cholera outbreak caused by a non-haemolytic polymixin B sensitive AET strain, occurred from July 8 to 13, 2018, in a remote settlement in western India. The molecular characterization of the outbreak strains highlighted an assortment of genetic determinants, stressing the need to monitor the genetic attributes of V. cholerae O1 in outbreaks for better understanding and mapping of clinical and epidemiological changes.

Seroprevalence of SARS-CoV-2 infection among frontline police personnel in Mumbai, India

Introduction

A serosurvey was designed to ascertain the extent of infection among police personnel in Mumbai, India, during the last week of January 2021, at the end of the first wave of the COVID-19 pandemic, and just before the introduction of vaccination.

Methods

The survey was carried out to screen for SARS-CoV-2 among 3232 police personnel. Of the 3176 participants willing for blood sample collection, 3077 personnel were found to be eligible for testing antibodies against the SARS-CoV-2 virus using the Roche Diagnostics’ Elecsys Anti-SARS-CoV-2 assay.

Results

The overall seroprevalence was 74.1% (95% CI 72.5–75.6). Males (75.1%, 73.4–76.8) had significantly higher seroprevalence than females (69.8%, 66.0-73.3), 18–39 years age group (76.4%, 74.4–78.3) than 40–59 years age group (70.6%, 67.9–73.1), non-officers (75.2%, 73.5–76.7) than officers (63.8%, 58.2–69.0), and personnel without comorbidities (75.0%, 73.3–76.6) than with comorbidities (69.7%, 65.6–73.5). Additionally, personnel with resident members positive for COVID-19 (89.6%, 84.7–93.1), personnel having reported COVID-19 earlier (95.5%, 93.8–96.7), and personnel having PCR positivity earlier (96.4%, 94.7–97.6) had significantly higher seroprevalences than others. All other variables, including diabetes and blood glucose status, lipid levels and thyroid enzymes, were not significantly associated with the seroprevalence levels.

Conclusions

Almost three-fourths of frontline police personnel had evidence of past COVID-19 infection at the end of the first wave in January 2021, just before the introduction of COVID-19 vaccination. These frontline non-healthcare essential workers are an important risk group, and amenable to rapid serosurveys. These findings may help in estimating transmission status in the general community, along with disease burden, aiding prioritization of healthcare services.

District-wise estimation of Basic reproduction number (R0) for COVID-19 in India in the initial phase

SARS-CoV-2 or COVID-19 was introduced into India by multiple sources generating local clusters and leading to the nationwide spread. A retrospective study has been conducted on the epidemiological features and spatial spread of COVID-19 in India during February 2020–March 2021. For each district, the cumulative number of confirmed COVID-19 cases were fitted to exponential growth model for the initial phase of the outbreak (the first 7–15 days). From the estimated growth rate, epidemiological parameters like the Basic reproduction number (R₀) and epidemic doubling time (τ) were determined. Using Q-GIS software, we have generated the all India distribution maps for R₀ and τ. COVID-19 spread rapidly covering majority of the districts of India between March and June 2020. As on 1st March 2021, a total of 715 out of 717 districts have been affected. The R₀ range is at par with the global average. A few districts, where outbreaks were caused by migrant workers coming home, intense transmission was recorded R₀ > 7. We also found that the spread of COVID-19 was not uniform across the different districts of India. The methodology developed in the study can be used by researchers and public health professionals to analyze and study epidemics in future.

Childhood encephalitis hospitalizations associated with virus agents in medium-endemic states in India

BACKGROUND

Japanese encephalitis (JE) is the leading cause of childhood acute encephalitis syndrome (AES) in India. We enhanced the AES surveillance in sentinel hospitals to determine trends and virus etiologies in central India.

METHODS

The neurological hospitalizations among children ≤15 years were tracked by using the AES case definition implemented by the national program. Acute and convalescent sera along with cerebrospinal fluid (CSF) specimens were collected and tested at the strengthened site hospital laboratories for anti-JE, anti-Dengue and anti-Chikungunya virus by IgM ELISA; along with Chandipura virus RT-PCR. Herpes simplex and enterovirus testing was undertaken at the reference laboratory.

RESULTS

Among 1619 pediatric neurological hospitalizations reported during 2015-16, AES case definition was fulfilled in 332 (20.5%) cases. After excluding 52 non-AES cases, 280 AES cases resident from study districts were considered eligible for study. The treating physicians diagnosed non-viral causes in 90 cases, therefore 190 (67.9%) of 280 AES cases were suspected with viral etiologies. We enrolled 140 (73.7%) of 190 eligible AES cases. Viral etiologies were confirmed in 31 (22.1%) of 140 enrolled AES cases. JE (n = 22) was the leading cause. Additional non-JE viral agents included Chikungunya (5), Dengue (2) and Chandipura (2). However, only 21 (9.4%) of 222 additional AES cases referred from peripheral hospitals were confirmed as JE.

CONCLUSIONS

Japanese encephalitis virus continues to be the leading cause of childhood acute encephalitis syndrome in central India despite vaccination program. Surveillance needs to be intensified for assessing the true disease burden of Japanese encephalitis following vaccination program implementation.

Seroprevalence of Dengue Infection Using IgG Capture ELISA in India, 2017-2018

We conducted a nationally representative population-based survey in 60 districts from 15 Indian states covering all five geographic regions during 2017-2018 to estimate the age specific seroprevalence of dengue. Of the 12,300 sera collected, 4,955 were positive for IgG antibodies against dengue virus using IgG Indirect ELISA indicating past dengue infection. We tested 4,948 sera (seven had inadequate volume) positive for IgG antibodies on indirect ELISA using anti-dengue IgG capture ELISA to estimate the proportion of dengue infections with high antibody titers, suggestive of acute or recent secondary infection. Of the 4,948 sera tested, 529 (10.7%; 95% CI: 9.4-12.1) were seropositive on IgG capture ELISA. The proportions of dengue infections with high titers were 1.1% in the northeastern, 1.5% in the eastern, 6.2% in the western, 12.2% in the southern, and 16.7% in the northern region. The distribution of dengue infections varied across geographic regions, with a higher proportion of infections with high antibody titer in the northern and southern regions of India. The study findings could be useful for planning facilities for clinical management of dengue infections.

Immunity against diphtheria among children aged 5-17 years in India, 2017-18: a cross-sectional, population-based serosurvey

BACKGROUND

Diphtheria is re-emerging as a public health problem in several Indian states. Most diphtheria cases are among children older than 5 years. In this study, we aimed to estimate age-specific immunity against diphtheria in children aged 5-17 years in India.

METHODS

We used residual serum samples from a cross-sectional, population-based serosurvey for dengue infection done between June 19, 2017, and April 12, 2018, to estimate the age-group-specific seroprevalence of antibodies to diphtheria in children aged 5-17 years in India. 8309 serum samples collected from 240 clusters (122 urban and 118 rural) in 60 selected districts of 15 Indian states spread across all five geographical regions (north, northeast, east, west, and south) of India were tested for the presence of IgG antibodies against diphtheria toxoid using an ELISA. We considered children with antibody concentrations of 0·1 IU/mL or greater as immune, those with levels less than 0·01 IU/mL as non-immune (and hence susceptible to diphtheria), and those with levels in the range of 0·01 to less than 0·1 IU/mL as partially immune. We calculated the weighted proportion of children who were immune, partially immune, and non-immune, with 95% CIs, for each geographical region by age group, sex, and area of residence (urban vs rural).

FINDINGS

29·7% (95% CI 26·3-33·4) of 8309 children aged 5-17 years were immune to diphtheria, 10·5% (8·6-12·8) were non-immune, and 59·8% (56·3-63·1) were partially immune. The proportion of children aged 5-17 years who were non-immune to diphtheria ranged from 6·0% (4·2-8·3) in the south to 16·8% (11·2-24·4) in the northeast. Overall, 9·9% (7·7-12·5) of children residing in rural areas and 13·1% (10·2-16·6) residing in urban areas were non-immune to diphtheria. A higher proportion of girls than boys were non-immune to diphtheria in the northern (17·7% [12·6-24·2] vs 7·1% [4·1-11·9]; p=0·0007) and northeastern regions (20·0% [12·9-29·8] vs 12·9% [8·6-19·0]; p=0·0035).

INTERPRETATION

The findings of our serosurvey indicate that a substantial proportion of children aged 5-17 years were non-immune or partially immune to diphtheria. Transmission of diphtheria is likely to continue in India until the immunity gap is bridged through adequate coverage of primary and booster doses of diphtheria vaccine.

FUNDING

Indian Council of Medical Research.

Hepatitis-B virus infection in India: Findings from a nationally representative serosurvey, 2017-18

INTRODUCTION

India introduced a hepatitis-B (HB) vaccine in the Universal Immunization Program in 2002-2003 on a pilot basis, expanded to ten states in 2007-2008 (phase-1), and the entire country in 2011-2012 (phase-2). We tested sera from a nationally representative serosurvey conducted duing 2017, to estimate the seroprevalence of different markers of HB infection among children aged 5-17 years in India and to assess the impact of vaccination.

METHODS

We tested sera from 8273 children for different markers of HB infection and estimated weighted age-group specific seroprevalence of children who were chronically infected (HBsAg and anti-HBc positive), and immune due to past infection (anti-HBc positive and HBsAg negative), and having serological evidence of HB vaccination (only anti-HBs positive). We compared the prevalence of serological markers among children born before (aged 11-17 years) and after (aged 5-10 years) introduction of HB-vaccine from phase-1 states.

RESULTS

Among children aged 5-8 years, 1.1% were chronic carriers, 5.3% immune due to past infection, and 23.2% vaccinated. The corresponding proportions among children aged 9-17 years were 1.1%, 8.0%, and 12.0%, respectively. In phase-1 states, children aged 5-10 years had a significantly lower prevalence of anti-HBc (4.9% vs. 7.6%, p<0.001) and higher prevalence of anti-HBs (37.7% vs. 14.7%, p<0.001) compared to children aged 11-17 years. HBsAg positivity, however, was not different in the two age groups.

CONCLUSIONS

Children born after the introduction of HB vaccination had a lower prevalence of past HBV infection and a higher prevalence of anti-HBs. The findings of our study could be considered as an interim assessment of the impact of the hepatitis B vaccine introduction in India.

Burden of dengue infection in India, 2017: a cross-sectional population based serosurvey

BACKGROUND

The burden of dengue virus (DENV) infection across geographical regions of India is poorly quantified. We estimated the age-specific seroprevalence, force of infection, and number of infections in India.

METHODS

We did a community-based survey in 240 clusters (118 rural, 122 urban), selected from 60 districts of 15 Indian states from five geographical regions. We enumerated each cluster, randomly selected (with an Andriod application developed specifically for the survey) 25 individuals from age groups of 5-8 years, 9-17 years, and 18-45 years, and sampled a minimum of 11 individuals from each age group (all the 25 randomly selected individuals in each age group were visited in their houses and individuals who consented for the survey were included in the study). Age was the only inclusion criterion; for the purpose of enumeration, individuals residing in the household for more than 6 months were included. Sera were tested centrally by a laboratory team of scientific and technical staff for IgG antibodies against the DENV with the use of indirect ELISA. We calculated age group specific seroprevalence and constructed catalytic models to estimate force of infection.

FINDINGS

From June 19, 2017, to April 12, 2018, we randomly selected 17 930 individuals from three age groups. Of these, blood samples were collected and tested for 12 300 individuals (5-8 years, n=4059; 9-17 years, n=4265; 18-45 years, n=3976). The overall seroprevalence of DENV infection in India was 48·7% (95% CI 43·5-54·0), increasing from 28·3% (21·5-36·2) among children aged 5-8 years to 41·0% (32·4-50·1) among children aged 9-17 years and 56·2% (49·0-63·1) among individuals aged between 18-45 years. The seroprevalence was high in the southern (76·9% [69·1-83·2]), western (62·3% [55·3-68·8]), and northern (60·3% [49·3-70·5]) regions. The estimated number of primary DENV infections with the constant force of infection model was 12 991 357 (12 825 128-13 130 258) and for the age-dependent force of infection model was 8 655 425 (7 243 630-9 545 052) among individuals aged 5-45 years from 30 Indian states in 2017.

INTERPRETATION

The burden of dengue infection in India was heterogeneous, with evidence of high transmission in northern, western, and southern regions. The survey findings will be useful in making informed decisions about introduction of upcoming dengue vaccines in India.

FUNDING

Indian Council of Medical Research.

Evidence of hepatitis A virus infection in the patients with acute encephalitis syndrome in Gorakhpur region, North India

The etiological agent remained unidentified in a large number of patients hospitalized for acute encephalitis syndrome (AES) in 2008-2009 in Uttar Pradesh and Bihar, north India. All patients were found to present with fever and altered sensorium, while 28%, 19% and 13% showed hepatomegaly, splenomegaly and meningeal signs, respectively. Involvement mostly of children with abnormal hepatic features prompted us to undertake an exploratory study on viral hepatitis A to determine its association, if any, with hepatic derangements. AES patients (n = 2515) and healthy children (n = 167) were investigated for the presence of serum anti-hepatitis A virus (anti-HAV) IgM and anti-Japanese encephalitis (anti-JE) virus IgM by ELISA. Cerebrospinal fluids (CSFs, n = 595) and rectal swabs (n = 182) were examined for anti-HAV IgM and/or HAV RNA. Anti-HAV IgM was detected in the sera of 14.6% patients as against 6.6% of healthy children (p = 0.0042). Anti-JE virus IgM positivity was Keywords: acute encephalitis syndrome; cerebrospinal fluid; hepatitis A virus; anti-HAV IgM; non-Japanese encephalitis.

Bacteriological Study Among Influenza-like Illness Cases in a Community Setting in Pune, India

Influenza-like illness (ILI) and acute respiratory infection (ARI) are common presentations during winter, and indiscriminate antibiotic use contributes significantly to the emerging post-antibiotic era. Although viral agents causing ILI are predominant, they are indistinguishable from the bacterial agents based on the clinical features alone. The present study was aimed at determining the bacterial agents associated with ILI and their susceptibility pattern during a study done in a community setting in Pune during a surveillance of ILI between March 2013 to November 2016.

Throat swabs from 512 suspected ILI cases were processed, and organisms were identified by the standard conventional method. An antimicrobial susceptibility testing was done as per the Clinical Laboratory Standard Institute (CLSI) guidelines.

The patients comprised 238 males and 274 females with the majority (38.7%) in the age group of ≤10 years. Bacteria could be isolated from 9.8 % of the patients. The predominant bacteria included beta-hemolytic Streptococcus (42%) followed by group G Streptococcus (30%) and group A Streptococcus (20%).

All organisms were sensitive to Penicillin except two isolates of Staphylococcus aureus (50%). Tetracycline (98.8%) and ciprofloxacin (87%) were the next most effective drugs. Overall resistance was observed for erythromycin (37%) and co-trimoxazole (32%).

Seroprevalence of Japanese encephalitis virus & West Nile virus in Alappuzha district, Kerala

BACKGROUND & OBJECTIVES

Several outbreaks of acute encephalitis syndrome (AES) have been reported in Alappuzha district, Kerala State, India, in the past. The aetiology of these outbreaks was either inconclusive or concluded as probable Japanese encephalitis virus (JEV) infection based on clinical presentation. The role of West Nile virus (WNV) in AES outbreaks was also determined. However, the extent of WNV infection has not been studied in this region previously. A population-based cross-sectional serosurvey study was undertaken to determine the seroprevalence of JEV and WNV in Alappuzha district.

METHODS

A total of 30 clusters were identified from 12 blocks and five municipalities as per the probability proportional to size sampling method. A total of 1125 samples were collected from all age groups. A microneutralization assay was performed to estimate the prevalence of JEV and WNV neutralizing antibodies in the sample population.

RESULTS

Of 1125 serum samples tested, 235 [21.5%, 95% confidence interval (CI): 15.2-27.8%] and 179 (15.9%, 95% CI: 9.6-22.3%) were positive for neutralizing antibodies against WNV and JEV, respectively. In addition, 411 (34.5%, 95% CI: 26.7-42.2%) were positive for cross-reactive antibodies against flaviviruses.

INTERPRETATION & CONCLUSIONS

The study showed the seroprevalence of WNV and JEV antibodies in the surveyed area and the WNV seroprevalence was greater than JEV. It is necessary to create awareness in public and adopt suitable policy to control these diseases.

A large outbreak of Japanese encephalitis predominantly among adults in northern region of West Bengal, India

Unusual rise of acute encephalitis syndrome cases (AES) were reported in July 2014 in the northern region of West Bengal, India. Investigations were carried out to characterize the outbreak and to identify the associated virus etiology. This observational study is based on 398 line listed AES cases, mostly (70.8%, 282/398) adults, with case fatality ratio of 28.9% (115/398). Japanese encephalitis virus infection was detected in 134 (49.4%) among 271 AES cases tested and most of them (79.1%, 106/134) were adults. The study reports a large outbreak of genotype III Japanese encephalitis among adults in northern region of West Bengal, India. J. Med. Virol. 88:2004-2011, 2016. © 2016 Wiley Periodicals, Inc.

On the transmission pattern of Kyasanur Forest disease (KFD) in India

Kyasanur Forest disease (KFD), a tick-borne viral hemorrhagic fever, is endemic in five districts of Karnataka state, India. Recent reports of the spread of disease to neighboring districts of the Western Ghats, namely Chamarajanagar district in Karnataka, Nilgiri district in Tamil Nadu, Wayanad and Malappuram districts in Kerala, and Pali village in Goa are a cause for concern. Besides vaccination of the affected population, establishing an event-based surveillance system for monkey deaths in the national parks, wildlife sanctuaries and reserve forests of the Western Ghats would help detect the disease early and thereby help implement appropriate control measures.

New focus of Kyasanur Forest disease virus activity in a tribal area in Kerala, India, 2014

Background

Kyasanur Forest disease (KFD) is a febrile illness characterized by hemorrhages, and is reported endemic in the Shimoga district in Karnataka state, India. It is caused by the KFD virus (KFDV) of the family Flaviviridae, and is transmitted to monkeys and humans by Haemaphysalis ticks.

Findings

We investigated a new focus of KFD among tribals in a reserve forest in Kerala state, India. A suspected case was defined as a person presenting with acute fever, headache, or myalgia. Human sera were collected and tested for KFDV RNA by real-time RT-PCR, RT-nPCR assay, and anti-KFDV IgM and IgG by ELISA. The index case was a tribal woman with febrile illness, severe myalgia, gum bleeding, and hematemesis. Anti-KFDV IgM antibody was detected in acute and convalescent sera of the index case along with IgG in the second serum. None of her family members reported fever. On verbal autopsy, two more fatal cases were identified as probable primary cases. Acute serum from a case in the second cluster was detected positive for KFDV RNA by real time RT-PCR (Ct = 32) and RT-nPCR. Sequences of E gene showed highest similarity of 98.0% with the KFDV W-377 isolate nucleotide and 100% identity with amino acid. Anti-KFDV IgM was detected in the serum of one family member of the index case, as well as in one out of 17 other tribals.

Conclusions

We confirmed a new focus of KFDV activity among tribals in a reserve forest in the Malappuram district of Kerala, India.

Electronic supplementary material

The online version of this article (doi:10.1186/s40249-015-0044-2) contains supplementary material, which is available to authorized users.

Antibody persistence after Pandemic H1N1 2009 influenza vaccination among healthcare workers in Pune, India

The healthcare workers having seroprotection at 3 weeks (n = 127) following Pandemic H1N1 2009 influenza vaccination were followed up for antibody persistence. Seroprotection at 12 mo (60.2%) was significantly lower as compared with 3 weeks (74.7%), 3 mo (77.8%) and 6 mo (75.4%). The vaccine provided seroprotection up to one year.

Avian influenza H9N2 seroprevalence among poultry workers in Pune, India, 2010

Avian influenza (AI) H9N2 has been reported from poultry in India. A seroepidemiological study was undertaken among poultry workers to understand the prevalence of antibodies against AI H9N2 in Pune, Maharashtra, India. A total of 338 poultry workers were sampled. Serum samples were tested for presence of antibodies against AI H9N2 virus by hemagglutination inhibition (HI) and microneutralization (MN) assays. A total of 249 baseline sera from general population from Pune were tested for antibodies against AI H9N2 and were negative by HI assay using ≥40 cut-off antibody titre. Overall 21 subjects (21/338 = 6.2%) were positive for antibodies against AI H9N2 by either HI or MN assays using ≥40 cut-off antibody titre. A total of 4.7% and 3.8% poultry workers were positive for antibodies against AI H9N2 by HI and MN assay respectively using 40 as cut-off antibody titre. This is the first report of seroprevalence of antibodies against AI H9N2 among poultry workers in India.

Low Level of Cross-Reactive Antibodies to Pandemic Influenza (H1N1) 2009 Virus in Humans in Pre-Pandemic Period in Maharashtra, India

In India, the first outbreak of pandemic influenza (H1N1) 2009 (H1N1pdm) was reported from Panchgani, Maharashtra, in June 2009. Studies from several countries have revealed different levels of pre-existing immunity to H1N1pdm 2009 in various age groups. This study was undertaken using age-stratified pre-pandemic human sera to understand baseline cross-reactivity of antibodies against H1N1pdm. Using cut off antibody titers 20 and 40, overall cross-reactivity was 2.1 and 0.9% respectively by microneutralization assay; 1.2% and 0.7% by haemagglutination inhibition assay, respectively. Results showed higher baseline antibodies and cross-reactive antibodies in the 0-19 age group whereas the elderly age group (≥60) showed no cross-reactivity to H1N1pdm. The higher baseline and cross-reactive antibodies in 0-19 years age group could be because of higher positivity to seasonal H1N1 in that age group. Overall, low level of cross-reactive antibodies to H1N1pdm virus were found in humans in pre-pandemic period in Maharashtra, India.

Buffalopox outbreak in humans and animals in Western Maharashtra, India

An outbreak of febrile illness with rash was reported in humans and buffaloes with pox lesions in some villages of Solapur and Kolhapur districts of Maharashtra state, India. Detailed clinico-epidemiological investigations were done with collection of blood, vesicular fluid and scab from humans and animals. A total of 166 suspected human cases from Kasegaon village in Solapur district and 185 cases were reported from 21 different villages from Kolhapur district. The attack rate in humans in Kasegaon village was 6.6% while in Kolhapur district the attack rate for buffaloes was 11.7%. Pox-like lesions were associated with fever, malaise, pain at site of lesion and axillary and inguinal lymphadenopathy in the humans. Infected buffaloes had lesions on teats, udders, external ears and eyelids. Laboratory investigations included detection of Buffalopox virus (BPXV) by electron microscopy (EM), virus isolation and polymerase chain reaction (PCR). Presence of BPXV was confirmed in 7 human cases and one buffalo in Kasegaon and 14 human cases from Kolhapur. The virus was isolated from 3 clinical specimens and Orthopoxvirus (OPXV) particles could be observed in EM. Thus, BPXV was identified as the etiological agent of the outbreak among both humans and buffaloes. Phylogenetic analysis based on the ATI and C18L gene revealed that a single strain of virus is circulating in India. Re-emergence of OPXV like BPXV is a real danger and contingency planning is needed to define prophylactic and therapeutic strategies to prevent or stop an epidemic. Considering the productivity losses caused by buffalopox infection and its zoonotic impact, the importance of control measures in reducing the economic and public health impact cannot be underestimated.

Chandipura virus encephalitis outbreak among children in Nagpur division, Maharashtra, 2007

BACKGROUND & OBJECTIVES

An outbreak of acute encephalitis syndrome (AES) among children from Nagpur division, Maharashtra was investigated to confirm the aetiology and to describe clinico-epidemiological features.

METHODS

AES cases among children<15 yr, from Nagpur division, hospitalized between June-September 2007, were investigated. Serum and cerebrospinal fluid (CSF) were tested for IgM antibodies against Chandipura virus (CHPV) and Japanese encephalitis virus (JEV) and for CHPV RNA by RT-PCR. Partial N gene sequences were used for phylogenetic analysis. Virus isolations were attempted in rhabdomyosarcoma (RD) cell line. Sandflies were collected, pooled and tested for CHPV RNA by RT-PCR.

RESULTS

A total of 78 AES cases were recorded in children<15 yr of age. Case fatality ratio was 43.6 per cent. Male to female ratio was 1:1.2. Chandipura (CHP) was confirmed in 39 cases. CHPV RNA was detected in both CSF and serum specimens of 2 cases and in serum of 22 cases. Phylogenetic analysis showed 99.98-100 per cent nucleotide identity in the sequences studied. Anti-CHPV IgM antibodies were detected in CSF of 2 cases and in serum of 8 cases. Seroconversion to anti-CHPV IgM antibodies was observed in 5 cases. Clinical manifestations of CHP cases (n=38) were fever (100%), convulsion (76.3%), altered sensorium (34.2%), headache (23.7%), vomiting (44.7%) and diarrhoea (23.7%). CHPV RNA was detected in one of two pools of sandflies from affected locality.

INTERPRETATION & CONCLUSIONS

Chandipura virus was confirmed as the aetiological agent of this acute encephalitis outbreak with high case-fatality among children.

Development and evaluation of a real-time one step reverse-transcriptase PCR for quantitation of Chandipura virus

Background

Chandipura virus (CHPV), a member of family Rhabdoviridae was attributed to an explosive outbreak of acute encephalitis in children in Andhra Pradesh, India in 2003 and a small outbreak among tribal children from Gujarat, Western India in 2004. The case-fatality rate ranged from 55–75%. Considering the rapid progression of the disease and high mortality, a highly sensitive method for quantifying CHPV RNA by real-time one step reverse transcriptase PCR (real-time one step RT-PCR) using TaqMan technology was developed for rapid diagnosis.

Methods

Primers and probe for P gene were designed and used to standardize real-time one step RT-PCR assay for CHPV RNA quantitation. Standard RNA was prepared by PCR amplification, TA cloning and run off transcription. The optimized real-time one step RT-PCR assay was compared with the diagnostic nested RT-PCR and different virus isolation systems [in vivo (mice) in ovo (eggs), in vitro (Vero E6, PS, RD and Sand fly cell line)] for the detection of CHPV. Sensitivity and specificity of real-time one step RT-PCR assay was evaluated with diagnostic nested RT-PCR, which is considered as a gold standard.

Results

Real-time one step RT-PCR was optimized using in vitro transcribed (IVT) RNA. Standard curve showed linear relationship for wide range of 10²-10¹⁰ (r² = 0.99) with maximum Coefficient of variation (CV = 5.91%) for IVT RNA. The newly developed real-time RT-PCR was at par with nested RT-PCR in sensitivity and superior to cell lines and other living systems (embryonated eggs and infant mice) used for the isolation of the virus. Detection limit of real-time one step RT-PCR and nested RT-PCR was found to be 1.2 × 10⁰ PFU/ml. RD cells, sand fly cells, infant mice, and embryonated eggs showed almost equal sensitivity (1.2 × 10² PFU/ml). Vero and PS cell-lines (1.2 × 10³ PFU/ml) were least sensitive to CHPV infection. Specificity of the assay was found to be 100% when RNA from other viruses or healthy individual was used.

Conclusion

On account of the high sensitivity, reproducibility and specificity, the assay can be used for the rapid detection and quantitation of CHPV RNA from clinical samples during epidemics and from endemic areas. The assay may also find application in screening of antiviral compounds, understanding of pathogenesis as well as evaluation of vaccine.

Chandipura virus: a major cause of acute encephalitis in children in North Telangana, Andhra Pradesh, India

A hospital-based surveillance was undertaken between May 2005 and April 2006 to elucidate the contribution of Chandipura virus (CHPV) to acute viral encephalitis cases in children, seroconversion in recovered cases and to compare the seroprevalences of anti-CHPV IgM and N antibodies in areas reporting cases with those without any case of acute viral encephalitis. During this period, 90 cases of acute encephalitis were hospitalized in the pediatric wards of Mahatma Gandhi Memorial (MGM) Hospital, Warangal. There were 49 deaths (Case Fatality Rate, i.e., CFR of 54.4%). Clinical samples and records were obtained from 52 suspected cases. The cases were below 15 years, majority in 0-4 years (35/52, 67.3%). Computerized tomography (CT) scans and cerebro-spinal fluid (CSF) picture favored viral etiology. No neurological sequelae were observed. CHPV etiology was detected in 25 cases (48.1%, n = 52; RNA in 20, IgM in 3 and N antibody seroconversion in 2). JEV etiology was detected in 5 cases (IgM in 4 cases and seroconversion in 1 case). Anti-CHPV IgM seroprevalence in contacts (26/167, 15.6%) was significantly higher (P < 0.05) than in non-contacts (11/430, 2.6%); which was also observed in children <15 years (19/90, 21.1% vs. 3/109, 2.7%). Anti-CHPV N antibody seroprevalence in <15 years contacts (66/90, 73.3%) and non-contacts (77/109, 70.6%) was significantly lower (P < 0.05) than in contacts (75/77, 97.4%) and non-contacts (302/321, 94.1%) more than 15 years respectively. CHPV appears to be the major cause of acute viral encephalitis in children in endemic areas during early monsoon months.

Chikungunya outbreaks caused by African genotype, India

Chikungunya fever is reported in India after 32 years. Immunoglobulin M antibodies and virus isolation confirmed the cause. Phylogenic analysis based on partial sequences of NS4 and E1 genes showed that all earlier isolates (1963–1973) were Asian genotype, whereas the current and Yawat (2000) isolates were African genotype.