Seropositivity of Anti-SARS CoV2 IgG antibodies in health care workers of an Indian tertiary care hospital during COVID-19

Purpose: Health care workers [HCW] are at a higher risk of infection SARS CoV2 infection due to frequent and close contact to patients with COVID-19. Methods: Serum samples from 500 HCW's were tested for SARS CoV2 IgG antibodies in October 2020. A questionnaire was used to collect demographic and clinical data. All these HCWs were tested for COVID-19, in 2nd week of September 2020, as a hospital policy. Results: Anti SARS CoV2 antibodies were detected in 128/ 500 [25.6%] HCWs. A total of 195/ 500 [39%] enrolled cases had already tested positive for Covid-19 at least once in last six months by RT-PCR. Sixty eight percent of HCWs with previous COVID-19 positivity by RT- PCR tested positive for Anti SARS CoV2 antibodies, whereas only 2.76% of asymptomatic HCWs tested positive. Of 121 anti SARS-CoV-2 IgG positive persons, 70 [57.85%] had CT value < 25. Low CT value and asymptomatic cases had a strong reverse statistically significant association with SARS CoV2 IgG antibody positivity. Conclusions: We report that sero-conversion rate in HCWs is similar to that in general population suggesting that preventive practices used in hospitals are satisfactory. Cases with low viral counts in respiratory sample and asymptomatic cases have lower rate of seroconversion.

Seroprevalence of anti SARS-CoV-2 IgG antibodies among adults in Jammu district, India: A community-based study

Background & objectives: Serology testing is essential for immunological surveillance in the population. This serosurvey was conducted to ascertain the cumulative population immunity against SARS-CoV-2 among adults in Jammu district and to understand the association of seropositivity with sociodemographic and clinical correlates. Methods: On September 30 and October 1, 2020, a household survey was done in 20 villages/wards chosen from 10 health blocks in district Jammu, India. Demographic, clinical and exposure information was collected from 2000 adults. Serum samples were screened for IgG antibodies using COVID Kavach MERILISA kit. Tests of association were used to identify risk factors associated with IgG positivity. Crude odds ratio with 95 per cent confidence intervals (CIs) was calculated during univariate analysis followed by logistic regression. Results: Overall adjusted seroprevalence for SARS-CoV-2 was 8.8 per cent (95% CI: 8.78-8.82); it varied from 4.1 per cent in Chauki choura to 16.7 per cent Pallanwalla across 10 blocks in the district. Seropositivity was observed to be comparatively higher in 41-50 and 61-70 yr age groups, among males and in rural areas. Fever, sore throat, cough, dyspnoea, myalgias, anosmia, ageusia, fatigue, seizures, history of exposure, medical consultation, hospitalization and missing work showed significant association with seropositivity on univariate analysis. On logistic regression, only sore throat, myalgia and missing work showed significant adjusted odds of IgG positivity. Extrapolation to adult population suggested that exposure to SARS-CoV-2 was 14.4 times higher than reported cases, translating into Infection fatality rate of 0.08 per cent. Interpretation & conclusions: Since a major part of population was immunologically naive, all efforts to contain COVID-19 need to be vigorously followed while these baseline results provide an important yardstick to monitor the trends of COVID-19 and guide locally appropriate control strategies in the region

Development of an Indirect ELISA Featuring Plates Coated with Column Chromatographically Purified Canine Adenovirus Type-1 Antigen

Canine adenovirus type 1 (CAV-1) causes infectious hepatitis in members of the family Canidae, including dogs. An indirect enzyme-linked immunosorbent assay (I-ELISA) that detects CAV-1 antibodies is required for large-throughput tests of dog sera. We collected 165 serum samples from dogs of Chungbuk and Gyeongbuk provinces between February 2016 and October 2018. The Korean CAV-1 vaccine strain CAV1V was propagated in Madin-Darby canine kidney (MDCK) cells and purified via Nuvia cPrime anion-exchange chromatography; the virus served as an I-ELISA antigen. Virus-neutralizing anti-CAV-1 titers in dog sera were measured using the virus neutralization (VN) method. The I-ELISA was optimized using purified CAV-1 antigen and serum samples. This kit was used to evaluate dog sera. The VN and I-ELISA data were compared. The sensitivity, specificity, and accuracy of the I-ELISA were 97.0%, 74.2%, and 92.7% compared to the VN assay, respectively. The I-ELISA data significantly correlated with those of VN (r = 0.88). These results suggest that the I-ELISA is useful for serosurveillance of CAV-1 in dog sera.

Detection of viral infections in wild Korean raccoon dogs (Nyctereutes procyonoides koreensis)

Wild raccoon dogs (Nyctereutes procyonoides koreensis) may play a role transmitting several pathogens to humans and pet animals. Information concerning the incidence of rabies, canine distemper virus (CDV), canine parvovirus (CPV), canine adenovirus type 2 (CAdV-2), canine parainfluenza virus type 5 (CPIV-5), and canine herpesvirus (CHV) is needed in wild raccoon dogs. In total, 62 brain samples of raccoon dogs were examined for rabies virus (RABV) and CDV, and 49 lung samples were screened for CDV, CAdV-2, CPIV-5, and CHV. No RABV, CAdV-2, CPIV-5, or CHV was identified, but nine CDV antigens (8.1%, 9/111) were detected. Moreover, 174 serum samples from wild raccoon dogs were screened for antibodies against the five major viral pathogens. The overall serosurveillance against CDV, CPV, CAdV-2, CPIV-5, and CHV in wild raccoon dogs was 60.3%, 52.9%, 59.8%, 23.6%, and 10.3%, respectively. Comparisons of the sero-surveillance of the five pathogens showed that raccoon dogs of Gyeonggi province have slightly higher sero-positive rates against CDV, CPV, and CHV than those of Gangwon province. These results indicate high incidences of CDV, CPV, and CAdV-2 in wild raccoon dogs of two Korean provinces and a latent risk of pathogen transmission to companion and domestic animals.

Indirect ELISA for the Detection of Rabies Virus Antibodies in Dog Sera

Rabies is known as the most fatal disease in all warm-blooded animals, including dogs. Among animals that transmit rabies, dogs are mainly responsible for transmitting animal rabies in Asian countries. Detection of rabies virus (RABV) antibodies in dogs is performed by fluorescent antibody virus neutralization (FAVN) test or rapid fluorescent focus inhibition test. These standard assays are difficult to carry out in diagnostic laboratories without sufficient instruments, designated RABV, and cell culture systems. An alternative assay that is easy to conduct and time efficient is required for rapid sero-surveillance following vaccination. Recombinant baculovirus expressing RABV nucleoprotein (RVN) was constructed and the recombinant protein was purified using Ni-NTA and fast protein liquid column chromatography. We developed and evaluated an indirect enzyme-linked immunosorbent assay (I-ELISA) with recombinant RVN for the detection of RABV antibodies in 122 dog serum samples. The I-ELISA results obtained from these samples were compared with FAVN results. The sensitivity, specificity, and accuracy of I-ELISA were 88.1%, 92.5%, and 91.0%, respectively, compared with FAVN. Results of I-ELISA were significantly correlated with that of FAVN (r = 0.81). These results suggest that I-ELISA with recombinant RVN is useful for sero-surveillance of RABV in dog sera.

Indirect ELISA for the Detection of Rabies Virus Antibodies in Dog Sera

Rabies is known as the most fatal disease in all warm-blooded animals, including dogs. Among animals that transmit rabies, dogs are mainly responsible for transmitting animal rabies in Asian countries. Detection of rabies virus (RABV) antibodies in dogs is performed by fluorescent antibody virus neutralization (FAVN) test or rapid fluorescent focus inhibition test. These standard assays are difficult to carry out in diagnostic laboratories without sufficient instruments, designated RABV, and cell culture systems. An alternative assay that is easy to conduct and time efficient is required for rapid sero-surveillance following vaccination. Recombinant baculovirus expressing RABV nucleoprotein (RVN) was constructed and the recombinant protein was purified using Ni-NTA and fast protein liquid column chromatography. We developed and evaluated an indirect enzyme-linked immunosorbent assay (I-ELISA) with recombinant RVN for the detection of RABV antibodies in 122 dog serum samples. The I-ELISA results obtained from these samples were compared with FAVN results. The sensitivity, specificity, and accuracy of I-ELISA were 88.1%, 92.5%, and 91.0%, respectively, compared with FAVN. Results of I-ELISA were significantly correlated with that of FAVN (r = 0.81). These results suggest that I-ELISA with recombinant RVN is useful for sero-surveillance of RABV in dog sera.

Seroepidemiological Survey of Zoonotic Diseases in Small Mammals with PCR Detection of Orientia tsutsugamushi in Chiggers, Gwangju, Korea

Serosurveillance for zoonotic diseases in small mammals and detection of chiggers, the vector of Orientia tsutsugamushi, were conducted from September 2014 to August 2015 in Gwangju Metropolitan Area. Apodemus agrarius was the most commonly collected small mammals (158; 91.8%), followed by Myodes regulus (8; 4.6%), and Crocidura lasiura (6; 3.5%). The highest seroprevalence of small mammals for O. tsutsugamushi (41; 26.3%) was followed by hantaviruses (24; 15.4%), Rickettsia spp. (22; 14.1%), and Leptospira (2; 1.3%). A total of 3,194 chiggers were collected from small mammals, and 1,236 of 3,194 chiggers were identified with 7 species of 3 genera: Leptotrombidium scutellare was the most commonly collected species (585; 47.3%), followed by L. orientale (422; 34.1%), Euchoengastia koreaensis (99; 8.0%), L. palpale (58; 4.7%), L. pallidum (36; 2.9%), Neotrombicula gardellai (28; 2.3%), and L. zetum (8; 0.6%). L. scutellare was the predominant species. Three of 1,236 chigger mites were positive for O. tsutsugamushi by PCR. As a result of phylogenetic analysis, the O. tsutsugamushi strain of chigger mites had sequence homology of 90.1-98.2% with Boryong. This study provides baseline data on the distribution of zoonotic diseases and potential vectors for the development of prevention strategies of vector borne diseases in Gwangju metropolitan area.

A Survey of Serum Bactericidal Antibodies against Neisseria meningitidis Serogroups A, C, W and Y in Adolescents and Adults in the Republic of Korea / 감염과화학요법

BACKGROUND: This descriptive epidemiological study aimed to assess the prevalence of serum bactericidal antibodies against Neisseria meningitidis serogroups A, C, W and Y in adolescents and adults in the Republic of Korea. MATERIALS AND METHODS: In total, 987 subjects aged 11-55 years from five geographical regions of Korea were included in the study. Human serum bactericidal assay (hSBA) was used to measure hSBA titres for serogroups A, C, W and Y. Percentages of subjects with hSBA titres ≥4 and ≥8, geometric mean titres (GMTs), and associated 95% confidence intervals (CIs), were estimated. Analysis was performed for the entire study population and stratified by age group or region. No statistical hypotheses were tested. RESULTS: The highest percentage of subjects with hSBA titres ≥8 was observed for serogroup W (74%), was similar for serogroups C (34%) and Y (36%), and was lowest for serogroup A (9%). The percentages of subjects with hSBA titres ≥4 were similar to those with hSBA titres ≥8 for all serogroups. GMTs were 2.56 µg/mL (serogroup A), 5.14 µg/mL (serogroup C), 22.63 µg/mL (serogroup W) and 5.28 µg/mL (serogroup Y). Similar trends in GMTs across serogroups were seen for individual regions and age groups. The highest GMTs for serogroups A, W and Y were recorded in the >19-29 years group, and for serogroup C in the >49-55 years group. Across all regions, GMTs were very similar for serogroups A, C and Y, while more variation was seen for serogroup W. CONCLUSION: In the Korean population, among Neisseria meningitidis serogroups A, C, W and Y, serum bactericidal antibodies were most prevalent against serogroup W and least prevalent against serogroup A. These trends were maintained across age groups and regions. The highest GMTs for serogroups A, W and Y were observed in the >19-29 years group. The reasons behind the observed differences in prevalence of bactericidal antibodies against the serogroups are currently not understood, although carriage and cross-reactivity of the assay may be important influences.

Sero-surveillance of Getah Virus among Thoroughbred Horses in Korea

Getah virus (GETV), which is transmitted by mosquitoes, causes lower limb edema and stiffness in horses. In this study, we investigated the sero-surveillance of GETV among Thoroughbred racehorses in Korea during 2013 and 2014. A total of 1,182 equine serum samples collected from Thoroughbred racehorses in four provinces (Gyeongnam, Gyeonggi, Jeonbuk and Jeju provinces) were analyzed using virus neutralization (VN) tests. An antibody titer of > or = 1:2 was considered positive. Overall, the seropositivity rate for GETV was found to be 12.4% (146/1,182) among the racehorses; the annual seropositivity rates were 12.4% and 12.2% in 2013 and 2014, respectively. The seropositivity rates in April and September in 2013 turned out to be 8.6% and 15.2%, respectively. The regional distribution of seropositivity ranged from 5.0% to 22.3% in 2013 and from 0.0% to 15.0% in 2014, respectively. Gyeongnam province had the highest seropositivity rate than other provinces. By analyzing the distribution of VN titers according to horse age, we found that the highest GETV seropositivity rate was in horses over 6 years of age (22.4% and 28.1%, 2013 and 2014, respectively), and that the incidence of GETV was higher in geldings (17.6% and 18.6%, 2013 and 2014, respectively) than in males and females. These results indicate that Thoroughbred horses raised in Korea were bitten by mosquitoes harboring GETV.

Serosurveillance and establishment of a reverse transcription-polymerase chain reaction assay for bovine parainfluenza virus type 5 / 대한수의학회지

Bovine parainfluenza virus type 5 (bPIV5) was isolated from cattle with downer cow syndrome in 2012, and included both respiratory and neurotropic pathogens from a variety of animals. In the current study, we conducted serosurveillance using sera obtained from seven Korean farms and optimized a reverse transcription-polymerase chain reaction (RT-PCR) assay to detect bPIV5. The overall seropositive rate for Korean cattle was 21.4% (163/760). A farm located near the city of Milyang in Gyeoungnam province had a markedly elevated seropositive rate for bPIV5 compared to that of the other six farms. The regional seropositive rates were 4.2% (8/192) for Haman, 19.5% (18/55) for Hwasung, 73.9% (65/88) for Milyang, 26.0% (50/192) for Namwon, 1.0% (1/96) for Uljin, 13.5% (13/96) for Yeongju, and 32.7% (8/41) for Yongin. The sensitivity and specificity of three RT-PCR primer sets used to amplify the conserved fusion gene of bPIV5 were also evaluated. An RT-PCR assay using the bPIVFR3 primer set was 10-fold more sensitive than the assays using the two other primer sets and did not result in non-specific amplification. These results demonstrated that the bPIFR3 primer set can be used to detect bPIV5.

Serologic Survey of Rabies Virus, Canine Distemper Virus and Parvovirus in Wild Raccoon Dogs (Nyctereutes procyonoides koreensis) in Korea

Oral rabies vaccination (ORV) program for the wild animals in rabies risk regions of Korea has been conducted since 2000. Evaluation of ORV program under field condition and information concerning the incidence of exposure to canine distemper and canine parvovirus (CPV) are needed in wild raccoon dogs (Nyctereutes procyonoides koreensis). Ninety four sera of wild raccoon dogs were screened for antibodies against rabies, canine distemper virus (CDV) and CPV in Korea. The overall prevalence of antibodies against rabies virus (RABV), CDV and CPV in wild raccoon dogs was 35.1%, 89.4% and 24.5%, respectively. Comparisons of sero-prevalences of RABV, CDV and CPV were assayed in two regions (Gyeonggi-do and Gangwon-do). The Gyeonggi-do (36.4%) showed higher sero-positive rate against CPV than Gangwon-do (20.8%). In contrast, Gangwon-do (41.7% and 97.2%) showed higher sero-positive rates against RABV and CDV than Gyeonggi-do (13.6% and 63.6%). These results indicate that there was severe circulation of CDV and CPV among wild raccoon dogs in the two regions of Korea. Furthermore, raccoon dogs showing a protective antibody titer (0.5 IU/ml) were 15.9%, suggesting that new rabies control program such as trap-vaccination-release (TVR) should be launched urgently in rabies risk regions.

ICMR’s tryst with HIV epidemic in India: 1986-1991.

The Indian Council of Medical Research (ICMR) undertook screening of asymptomatic persons from high risk group with the ELISA test for HIV infection in 1986 and found that HIV infection has reached India. ICMR in collaboration with the central and State health services initiated the national sero- surveillance programme for HIV infection in 43 surveillance and five reference centres to determine the major modes of transmission and magnitude of infection. Data from the sero-surveillance showed that HIV infection was present in all the known high risk groups and in the general population in all the States both in urban and rural areas. HIV was getting transmitted through all the known modes of transmission. In most States heterosexual transmission was predominant but in Manipur intravenous (iv) drug use was the most common mode of transmission. Prevalence of HIV infection in high risk groups was not high and that in low risk groups was quite low. ICMR initiated hospital based sentinel surveillance in high risk groups and general population to obtain time trends in seroprevalence. Between 1986 and 1991, National AIDS Programme was carried out as a collaborative effort of ICMR, and central and State health services. As the dimensions of the epidemic unfolded, rational evidence based interventions which could be implemented within the existing health system, were initiated. National AIDS Control Programme (NACP) continued and upscaled all these interventions. Effective implementation of a multi-pronged, rational strategy for HIV infection containment and control right from the initial stages, and dedicated work done by committed professionals belonging to government and voluntary sectors, cultural ethos of the country, responsible behaviour of the population and relatively low iv drug use have resulted in rapid decline in new infection and in prevalence of infection within a quarter of a century after the initial detection of HIV.

Chikungunya virus outbreak in Kerala, India, 2007: a seroprevalence study

India was affected by a major outbreak of chikungunya fever caused by Chikungunya virus (CHIKV) during 2006-2007. Kerala was the worst affected state during 2007 with a contribution of 55.8 percent suspected cases in the country. However, except for clinically reported case records, no systematic information is available on infection status of CHIKV in the region. Hence, we carried out a post-epidemic survey to estimate seroprevalence status [immunoglobulin G (IgG)] in the community using commercially available indirect immunofluorescence test. This methodology had been reported to be highly specific and sensitive for CHIKV infection. The study area selected was the worst affected mid-highlands region of Kerala which harbour vast area of rubber plantations. The study evidenced 68 percent of the population to be seropositive for CHIKV IgG. Males were found more affected than females (χ2 = 9.86; p = 0.002). Among males, prevalence was significantly higher in the age classes 21-30 (χ2 = 5.46; p = 0.019) and 31-40 (χ2 = 5.84; p = 0.016) years. This may be due to high occupational risk of the male population engaged in plantation activities exposed to infective bites of Aedes albopictus. The current study provides an insight into the magnitude of CHIKV outbreak in Kerala.

Serosurveillance for Japanese encephalitis virus in wild birds captured in Korea

Climate change induced by recent global warming may have a significant impact on vector-borne and zoonotic diseases. For example, the distribution of Japanese encephalitis virus (JEV) has expanded into new regions. We surveyed the levels of hemagglutination-inhibition (HI) antibodies against JEV (Family Flaviviridae, genus Flavivirus) in wild birds captured in Korea. Blood samples were collected from 1,316 wild birds including the following migratory birds: Oceanodroma castro (n = 4), Anas formosa (n = 7), Anas penelope (n = 20), Fulica atra (n = 30), Anas acuta (n = 89), Anas crecca (n = 154), Anas platyrhynchos (n = 214), Aix galericulata (n = 310), and Anas poecilorhyncha (n = 488). All were captured in 16 locations in several Korea provinces between April 2007 and December 2009. Out of the 1,316 serum samples tested, 1,141 (86.7%) were positive for JEV. Wild birds captured in 2009 had a higher seroprevalence of ant-JEV antibodies than those captured in 2007. Wild birds with an HI antibody titer of 1 : 1,280 or higher accounted for 21.2% (280/1,316) of the animals tested. These findings indicated that wild birds from the region examined in our study have been exposed to JEV and may pose a high risk for introducing a new JEV genotype into Korea.

Serosurveillance for Japanese encephalitis virus infection among equines in India

The seroprevalence of Japanese encephalitis virus (JEV) among equines was evaluated from January 2006 to December 2009 in 13 different states of India by hemagglutination inhibition (HI) test and virus neutralization test (VNT). Antibodies against JEV were detected in 327 out of 3,286 (10%) equines with a maximum prevalence reported in the state of Manipur (91.7%) followed by Gujarat (18.5%), Madhya Pradesh (14.4%), and Uttar Pradesh (11.6%). Evidence of JEV infection was observed in equines in Indore (Madhya Pradesh) where a 4-fold or higher rise in antibody titer was observed in 21 out of 34 horses in November 2007 to October 2006. In March 2008, seven of these horses had a subsequent 4-fold rise in JEV antibody titers while this titer decreased in nine animals. JEV-positive horse sera had a JEV/WNV (West Nile virus) ratio over 2.0 according to the HI and/or VNT. These results indicated that JEV is endemic among equines in India.

Dengue serosurveillance in Kolkata, facing an epidemic in West Bengal, India.

Background & objectives: A dengue outbreak occurred throughout West Bengal, India starting from August 2005. The objectives of this study were: (i) documentation of suspected cases, confirmed by MAC ELISA; (ii) a longitudinal serosurveillance of dengue in Kolkata by detecting denguespecific IgG and IgM antibodies in suspected cases and to note the seasonal incidence; (iii) to get information about proportion of primary, secondary and old dengue cases and persons free from dengue in the population tested; and (iv) to get some idea to forecast advent of dengue and dengue epidemic/precipitation of DHF. Methods: The epidemiological data were collected from different sources including Calcutta School of Tropical Medicine and Government of West Bengal. For serosurveillance in Kolkata, serum of each suspected patient was examined for detection of IgG and IgM antibodies using the microwell ELISA dengue fever kit. Results: Altogether, 6293 ELISA IgM reactive cases were documented out of 12,059 persons (52.18%) tested in the whole of West Bengal, involving 18 districts with 34 deaths. Serosurveillance of 1668 persons from August 2005 to December 2007 in Kolkata showed that only 18.1% (302) suffered from dengue, 6.03% (101) from primary, 12.03% (201) from secondary dengue, 20.44% (341) were not sufferers of dengue and 61.45% (1025) were old dengue cases. Though stray dengue cases were found perennially, most of the cases occurred in the post-monsoon season, with a peak in September. Of dengue patients, 63.24% (191) were males. Secondary dengue cases outnumbered primary dengue cases. So, possibility of DHF would remain in all age groups and in those persons who suffered from dengue on earlier occasion. Dengue cases drastically reduced in two subsequent post-epidemic years (2006 and 2007). Interpretation & conclusion: Dengue serosurveillance studies may give some idea about advent, intensity, transmission season, seasonal incidence, waxing and warning, and impending epidemic of dengue and DHF. A large-scale active longitudinal serosurvey along with the study of vector capacity and vector competence would provide more correct information.