Role of nuclear energy in carbon mitigation to achieve United Nations net zero carbon emission: evidence from Fourier bootstrap Toda-Yamamoto.

In this communication, the time series data of three major countries USA, France, and Japan from 1965 to 2020 for CO2 emission, GDP, and nuclear energy (NE) are evaluated. It also analyzed and validated the EKC hypothesis while using nuclear energy for electricity generation. Fourier ARDL is used to investigate the hypothesis criteria, and the Fourier bootstrap Toda-Yamamoto (FBTY) causality test is used for causal linkage between the variables as well as the wavelet coherence; it is also presented the time and frequency dependency of the variables. The CO2 mitigation by using the NE is also assessed for all three countries and assessed that the France, Japan, and USA mitigated the CO2 per year is 0.0463 million metric ton (MMT), 0.0239 and 0.0728 MMT per year respectively. Similar to that the SO2 is reduced by using the NE is 24.322, 43.527, and 132.592 MMT/year, and NOx is reduced by approximately 0.2847, 0.147, and 0.4478 MMT/year by France, Japan, and USA respectively by applying the NE for power generation. The evidence of the EKC, Fourier bootstrap and Toda-Yamamoto clarifies the important role of nuclear energy in terms of carbon mitigation to achieve UN net zero carbon emission by 2050. Hence, in order to meet the UN target of net zero carbon emission by 2050, the USA and Japan should increase the production of nuclear energy as France meets its 74.1% energy demand through NE by validating the EKC hypothesis; on the other hand, all the three countries should increase the production of tidal energy due to their geographical location as tides are much more predictable than wind and sun keeping in consideration to the expenses incurred and a full proof plan for disposing NE residuals in a safe place as NE residuals are highly radioactive and contains traces of thorium and uranium.

4-E analysis and multiple objective optimizations of a novel solar-powered cogeneration energy system for the simultaneous production of electrical power and heating.

Owing to its natural and rich advantages, exploration of solar energy technology has become increasingly popular in recent years to counter the growing crude oil prices. However, its universal adoption is still limited, not only due to environmental restrictions but also due to lower overall efficiency. Rankine cycle is optimised to conduct 4-E (Exergy, Energy, Economic and Ecological) analysis. Furthermore, three sets (R-113, R-11, and R-1233zd) of refrigerants are prioritised and ranked on the basis of 4-E analysis as outcomes. The contemporary study addressed all critical factors and explains the impact of solar irradiance, mass flow rate of molten salt and steam, turbine inlet pressure, and turbine inlet temperature which are eventually weighed and prioritised using combined multi-criteria decision making (MCDM) techniques. The energy efficiency, exergetic efficiency, power/ cost of electricity, and ecological emissions are taken as the indicators of the combined cycle, respectively. The energy efficiency of the hybrid system is improved to 75.07% after including cogeneration cycle, with an increment of 54.58%. In comparison to conventional thermal powerplant setups, the power/cost of electricity and ecological efficiency have been reduced by 68% and upgraded by 16%, correspondingly. Direct normal radiation is the most critical factor followed by turbine inlet temperature. Further, the result indicates that maximum exergy destruction that occurs in the central receiver declines to 39.92%, followed by heliostat and steam turbine which was 27% and 9.32% respectively. In conclusion, the hybrid cycle can furnish cheaper electricity, with lower carbon imprint in sustainable manner with better efficiency.

Intensified seed spices-based cropping systems for higher productivity, resource-use efficiency, soil fertility and profitability in arid and semi-arid regions of India.

Coriander, fenugreek, nigella etc. are collectively known as seed spices. They are "High value and low volume crops" and considered cash crops for the growers of arid and semi-arid regions of India. Coriander, fenugreek and nigella are grown during the rabi season and take hardly 130-140 days to attain full maturity. In this context, farmers are not able to develop income from available arable land round the year, even though they have sufficient resources as well as manpower. Therefore, coriander, fenugreek and nigella-based cropping systems, four of each (total 12) were evaluated during 3 consecutive years (2019-20 to 2021-22) for their productivity, resource-use efficiency, economics and soil fertility. The results showed that among the seed spices-based cropping systems, maximum system productivity (5193 kg ha-1), production efficiency (18.81 kg ha-1 day-1), water-use efficiency (2.31 kg ha-1 mm-1), economic efficiency (11.85 US $ ha-1 day-1), net return (3270 US $ ha-1), benefit:cost ratio (3.27) and available N (165.6 kg ha-1) were observed under nigella-green coriander-mungbean cropping system. Hence, seed spices growers are recommended to adopt nigella-green coriander-mungbean cropping system in order to realize better productivity, resource-use efficiency, soil fertility and profitability.

Lymphatic filariasis in East District, Sikkim.

East district of Sikkim has been considered as non-endemic for lymphatic filariasis (LF). However, a LF survey conducted during 2008 revealed microfilaria rate (mf rate) of 1.2%. The LF survey was carried out in 15 randomly selected villages and urban localities of East Sikkim. Out of 3,428 night blood smears collected and examined, 42 were found positive for Wuchereria bancrofti. Microfilaria (mf) carriers were detected from 5 surveyed villages and 5 urban localities of Singtam and Rangpoo with mf rate ranging from 0.5% to 4.2%. The mean mf density was 5.4 per 20cmm3 blood. All mf carriers were residents of east district, Sikkim except two persons who were from Bihar. The detection of microfilaria in young children who had never moved from the area indicates probable indigenous transmission. Out of 15 surveyed areas LF disease was found in 11 areas with prevalence ranging from 0.4% to 7.0%.(Disease rate was 1.6%) (1.7% for Males & 1.4% for females). One local individual was found with lymphoedema and also mf positive. Vector density ranged from 70 to 435 per ten-man-hours, sufficient for transmission of LF. 712 female Cx. quinquefasciatus were dissected to detect the filarial infection and none was found positive. The present survey findings indicate endemicity of filariasis in East district of Sikkim.

Role of information technology (IT) in public health, India (problems & prospects): Role of information communication technology (ICT) in disease surveillance under Integrated Disease Surveillance Project (IDSP).

Information Communication Technology (ICT) has proven to be a strong public health tool. Keeping the future need of country and building National Disease Surveillance System, Integrated Disease Surveillance Project (IDSP) was launched by Hon'ble Union Minister of Health & Family Welfare in November 2004. It is a decentralized, State based surveillance program in the country. It is intended to detect early warning signals of impending outbreaks and help initiate an effective response in a timely manner. One of the major components of the project is the - use of Information Technology for collection, collation, compilation, analysis and dissemination of data besides distance education and video conferencing. A network of 800 sites across India has been established through Satellite, Broadband and High end Video conferencing equipments. The network is managed by a team of data managers and data entry operators at all state surveillance units and district surveillance units respectively. The network was proven to be extremely useful to respond to the current influenza A H1N1 pandemic. It is proposed to extend the network to cover private sector and provide convergence with other National Health Programs.

Phylogenetic studies reveal existence of multiple lineages of a single genotype of DENV-1 (genotype III) in India during 1956-2007.

BACKGROUND: Dengue virus type 1 (DENV-1) have been mostly circulating silently with dominant serotypes DENV-2 and DENV-3 in India. However recent times have marked an increase in DENV-1 circulation in yearly outbreaks. Many studies have not been carried out on this virus type, leaving a lacunae pertaining to the circulating genotypes, since its earliest report in India. In the present study, we sequenced CprM gene junction of 13 DENV-1 isolated from Delhi and Gwalior (North India) between 2001-2007 and one 1956 Vellore isolate as reference. For comparison, we retrieved 11 other Indian and 70 global reference sequences from NCBI database, making sure that Indian and global isolates from all decades are available for comparative analysis. RESULTS: The region was found to be AT rich with no insertion or deletion. Majority of the nucleotide substitutions were silent, except 3 non-conservative amino acid changes (I --> T, A --> T and L --> S at amino acid positions 59,114 and 155 respectively) in the Indian DENV-1 sequences, sequenced in this study. Except two 1997-98 Delhi isolates, which group in genotype I; all other Indian isolates group in genotype III. All Indian genotype III DENV-1 exhibited diversity among them, giving rise to at least 4 distinct lineages (India 1-4) showing proximity to isolates from diverse geographic locations. CONCLUSION: The extensive phylogenetic analysis revealed consistent existence of multiple lineages of DENV-1 genotype III during the last 5 decades in India.

Genetic polymorphism of glutathione S-transferase M1 and T1 in Delhi population of Northern India.

Glutathione S-transferases (GSTs), protect cells from reactive chemical intermediates and oxidative stress. Among different classes of GSTs, GSTM1 (Mu) and GSTT1 (theta) are found to be genetically deleted. Present study was intended to genotype homozygous null distribution of GSTM1 and GSTT1 in healthy individuals of Delhi, located in Northern India. Out of 309 healthy individuals included in this study, we have found genetic deletion in 21% and 27.4%, GSTM1 and GSTT1 genes, respectively. A small proportion (0.7%) population showed deletion of both the genes. The prevalence of the GSTM1(*)0/0 and GSTT1(*)0/0 genotypes varied within India compared to communities in Chinese, Japanese, Korean and Caucasian.

Status of lymphatic filariasis in Lucknow District, Uttar Pradesh.

Lucknow district was endemic for lymphatic filariasis (LF). During March 2008, LF survey was carried out in 14 randomly selected villages (six Primary Health Centres) and 4 Mohallas of Lucknow city. Out of 3,654 night blood smears (NBS) collected and examined, 209 were found positive for Wuchereria bancrofti (micrifilaria rate: 5.7%). Microfilaria (mf) carriers were detected from all surveyed villages and Mohallas. The age of these positive persons ranged from 6-70 years. In all areas, prevalence of microfilaraemia generally increased with age up to 21-30 years. Males (6.7%) were more affected than females (3.9%). All mf carriers were residents of Lucknow district. Overall disease rate was 4.7%. In all, 175 individuals had disease manifestations of LF. Out of 108 males, 81 had hydrocele(75%). Disease rate was similar in males (4.7%) and females (4.8%). The mean mf density was 9.5 per 20 cmm blood, but no significant difference between males (9.4) and females (9.9). Vector density ranged from 150 to 810 per ten-man-hours. Infectivity and infection rates were 0.14%. The present survey indicates that filariasis is one of the major public health problems in surveyed areas.

Breeding ecology of visceral leishmaniasis vector sandfly in Bihar state of India.

Soil samples weighing 255.3 kg, collected from 50 villages of 5 visceral leishmaniasis (VL) endemic districts of Bihar state were examined for sandfly breeding, using the soil incubation method. Breeding of sandflies was detected in 46% of the villages and 7.3% of the soil samples examined. Intra-domestic soil was found to be infested with 2 species of sandflies, Phlebotomus argentipes Annandale and Brunetti and Phlebotomus papatasi (Scopoli). In comparison with human houses, P. argentipes was found to show greater propensity to breed in cattle sheds; breeding prevalences in villages and soil samples, for the species, were significantly higher in cattle sheds than in human houses. The preference for breeding sites by the sandflies appeared to be associated with the pH of the soil. P. argentipes thus preferred to breed in the alkaline soil of cattle shed, and P. papatasi in the soil with neutral pH, of human houses. The emergence of adult P. argentipes from soil samples was mainly observed from April to October.

Impact of HIV on genomic variability in the 5'UTR of HCV in Indian patients with HCV/HIV co-infection.

BACKGROUND: The impact of HIV on hepatitis C virus (HCV) genome during HCV/HIV co-infection is poorly understood. The present study was intended to unveil nucleotide sequence variability in the 5'-untranslated region (5'UTR) of HCV in co-infected cases. METHODS: Automated nucleotide sequencing of the 5'UTR of HCV from both mono- and co-infected cases was performed. RESULTS: Data analysis revealed deletion of a continuous stretch of 12 nucleotides (nt 240-251) from domain IIIc in 20% co-infected cases, but no long-stretch deletion was observed in HCV from mono-infected cases. On the contrary, there was no insertion in the 5'UTR of HCV from co-infectedcases, but there were insertions in domain II and III (3 mononucleotides and 2 dinucleotides) of the 5'UTR in mono-infected cases. CONCLUSION: Since domain III is known to be important for binding of 40S ribosomal subunit, deletion of a single stretch of 12 nucleotides in HCV from co-infected cases observed in the present study may have implications during HCV replication with or without HIV infection. Although this is the first report on genomic heterogeneity in the 5'UTR of HCV from HCV/HIV co-infected Indian patients, it would be worthwhile to study if similar changes are observed in other genes of HCV during co-infection.

Emergence of an independent lineage of dengue virus type 1 (DENV-1) and its co-circulation with predominant DENV-3 during the 2006 dengue fever outbreak in Delhi.

OBJECTIVES: The sudden emergence of dengue virus type 1 (DENV-1) and its co-circulation with predominant DENV-3 was the hallmark of the 2006 dengue fever outbreak in Delhi. Viruses that circulated between 1996 and 2005 in the City have been well characterized, but the genomic diversity in 2006 strains is not known. The present study was undertaken to reveal the emerging molecular genotype(s) and evolutionary trend of the viruses responsible for the dengue fever outbreak in Delhi during 2006. STUDY DESIGN: The CprM gene junction of the DENV isolates from the 2006 Delhi dengue fever outbreak were subjected to nucleotide sequencing. Comparative phylogenetic analysis was done using DENV-1 and DENV-3 sequences retrieved from the global database. RESULTS: Multiple sequence alignment revealed only substitutions, with no insertions or deletions. A dendrogram indicated emergence of a distinct lineage of DENV-1 (having similarity with the Comoros/Singapore 1993 and Delhi 1982 strains, but quite different from the Delhi 2005 lineage) and microevolution of the pre-circulating DENV-3. These findings point towards the circulation of two independent lineages of DENV-1 in Delhi during 2005 and 2006. CONCLUSIONS: It is feared that the introduction of an independent lineage of the outbreak-associated strain of DENV-1 and its co-circulation with the deeply-rooted strain of DENV-3 in Delhi may result in yet another, possibly more severe outbreak in the near future.

Investigation of an outbreak of chikungunya in Malegaon Municipal areas of Nasik district, Maharashtra (India) and its control.

BACKGROUND & OBJECTIVES: An outbreak of chikungunya fever occurred in Malegaon town of Nasik district of Maharashtra state, India during February and March 2006. A total of 4530 fever cases were reported during this period including 1781 cases which were admitted in different hospitals of the town. An entomological and epidemiological investigation was carried out in the affected villages during the outbreak to study the possible causes of the outbreak and to isolate the virus responsible. METHODS: Entomological evaluation was done as per WHO guidelines. Sera samples were collected by venipuncture from clinically suspected chikungunya patients in hospitals and also during house-to-house survey in affected villages. IgM antibodies to dengue virus were detected using IgM capture ELISA (PANBIO) and by "Haemagglutination inhibition test" for detection of antibodies against Chikungunya virus. Acute sera samples were inoculated in cell lines for virus isolation. The isolates were confirmed by RT-PCR. RESULTS: On investigation, it was found that water storage containers like cement tanks, plastic containers or earthen pots placed in front of the individual houses were the potential breeding sites for Aedes aegypti. Entomological survey carried out in the most affected areas revealed high Aedes indices. House, container and breteau indices were found to be 27.2, 16.19 and 35.1, respectively. Out of the 13 acute sera samples collected, virus was isolated in 10 samples. The isolates were confirmed by RT-PCR and sequencing using primers from nsP1 gene of Chikungunya virus (CHIKV, Accession No. EF077609, EF077610). Of the 17 convalescent sera tested, significant level of HI antibodies to CHIKV was detected in five samples. One sample was positive for IgM antibodies against dengue virus. Based on clinico-epidemiological features and laboratory findings, the illness was confirmed to be of chikungunya viral disease. CONCLUSION: Control measures targeting the vector population and personal protective measures against the mosquito bites were instituted. Extensive IEC campaign with the involvement of community and religious leaders helped in containment of the disease.

Studies on leptospirosis outbreaks in Peddamandem Mandal of Chittoor district, Andhra Pradesh.

An outbreak of leptospirosis in Peddamandem Mandal, Chittoor district, Andhra Pradesh occurred during Aug to Oct 2005. Out of 86 single human sera samples of suspected cases collected during the investigation, 49 (56.97%) samples from seven villages were found positive for leptospirosis both by DGM tests and IgM antibodies. Out of total 49 positive cases 16 (47.05%) were male and 33 (69.46%) female patients. The mean age of the positive cases were 42.7 years. There was no significant differences in male and female ratio and age groups in affected population. The higher degree of seropositivity was observed in adult females as they were mainly engaged in both domestic and peridomestic works. Geographical clustering of cases was evident. All the 49 positive cases had fever (100%). Myalgia (42.9%), stiffness of calf muscles (55.1%) and headache (32.6%) were the other major clinical features observed. There was only 1 (2.04%) case with conjunctival suffusion. None of the case presented with jaundice. All the suspected cases were tested negative for malaria, typhoid and dengue fever. In Peddamandem, contaminated water stagnation due to heavy rainfall and frequent contact of barefooted villagers with the infected sources registered higher incidence of leptospirosis. Most of the cases were from the contaminated water logged areas of the affected villages. In the affected villages none of the individual occupational category showed a significant association with seropositivity. It indicated that the transmission was from the common single category source in the villages i.e. contaminated stagnant water. The villagers living with livestocks and rodents were significantly associated with seropositivity.

Enteric opportunistic parasites among HIV infected individuals: associated risk factors and immune status.

Data on various etiologic agents causing diarrhea in human immunodeficiency virus type-1 (HIV-1) infected individuals are sparse in Delhi, India. The present study was undertaken to identify various causative agents, the role of associated risk factors and immune status. A case-control study was conducted among 75 HIV-1 infected individuals, 50 with and 25 without diarrheal infection. Fecal samples were screened for coccidian parasites, enteric protozoa, and helminthes by using various staining techniques. The CD4+ T-lymphocyte count was estimated. Enteric parasites were identified among 62.7% individuals, of which Cryptosporidium emerged as the single largest pathogen predominant among 33% of the individuals (P < 0.025). Other parasites diagnosed that were significantly associated with diarrhea were Giardia lamblia (13.3%), microsporidia (6.7%), and Isospora belli (2.7%). Chronic infected diarrheal cases were found to have polyparasitic infections. The mean CD4+ cell count was found to be lower among the diarrheal cases when compared with the non-diarrheal cases (mean, 141 cells/mm(3) versus 390 cells/mm(3)). Similarly, among diarrheal individuals, the chronic diarrheal cases had a comparatively lower CD4+ cell count than the acute cases (mean, 123 cells/mm(3) versus 265 cells/mm(3)). Risk factors found significant during multivariate analysis were: residence in a slum, exposure to pets and animals, use of public toilets, and practice of unsafe homosexual activity. Enteric coccidian parasites were identified as significant agents associated with diarrhea, especially among those with improper hygiene, multiple infections and a lower CD4+ cell count. Thus, this study emphasizes the need for routine screening of enteric parasites as well as education about practicing personal hygiene and taking timely and appropriate prophylactic measures.

Evaluation of Og4C3 antigen ELISA as a tool for detection of bancroftian filariasis under lymphatic filariasis elimination programme.

Diagnosis of Lymphatic Filariasis by microscopic examination of thick blood films (TBF) collected between 8.30 pm to 12 midnight, though highly specific is operationally problematic. We evaluated the TropBio Og4C3 serum ELISA as a tool for detection of W. bancrofti microfilaria carriers using Dried Blood Spots (DBS). The study was carried out in two parts (i) to test the sensitivity and specificity of the ELISA test for detection of circulating filarial antigen (CFA) in microfilaria (Mf) carriers vis-à-vis the conventional thick blood film (TBF) microscopy and its persistence in different categories of individuals during the course of disease viz., Endemic normals (n=51), microfilaria (Mf) carriers (n=27), acute cases (n=27), chronic cases (n=50) and a control group of non-endemic normals (n=48) using sera samples and ii) to study the utility of finger prick Dried Blood Spots (DBS) collected on filter paper for detection of Mf carriers and its comparison with another antigen detection assay, the Immunochromatographic test (ICT). Considering the non-endemic normals and microfilaria carriers, the ELISA test was found to have 100% sensitivity and 94.12% specificity for detection of Mf carriers in sera samples. The CFA was absent in majority of the subjects tested under other categories with a positivity of 7.8% among endemic normals, 11.12% among acute cases, 7.84% among chronic cases and 6.25% among nonendemic normals. Comparison of finger prick DBS and sera samples by ELISA vis-à-vis the ICT, carried out on Mf carriers (n=91) and endemic normals (n=97), showed a positivity of 88 (96.7%) in DBS as against 86 (94.5%) in sera samples and 88 (96.7%) by ICT, amongst Mf carriers, with a statistically significant correlation in antigen units between sera and DBS samples (r = 0.959, p = 0.000) amongst the microfilaria carriers. Out of 97 endemic normals, 19 (19.6%) sera and 17 (17.5%) DBS samples tested positive by ELISA while as 12(12.4%) tested positive by ICT, again with a statistically significant correlation between the antigen units in sera and DBS samples (r = 0.942, p = 0.000). DBS prepared from 25 microl of blood were found to be as sensitive as 50 microl for antigen detection. Antigen positivity detected from DBS collected during day and night from known microfilaria carriers (n=27) showed a statistically insignificant difference (p = 0.125) and a significant correlation in antigen units (r = 0.820 and p = 0.013). In view of the comparable results of ELISA, ICT and TBF microscopy, it is concluded that the TropBio Og4C3 ELISA using finger prick DBS can be used as an alternate to TBF microscopy for detection of bancroftian Filariasis under the LFE programme.

Chikungunya viral disease in district Bhilwara (Rajasthan) India.

An investigation of chikungunya outbreak cases was carried out in Bhilwara District, Rajasthan during Aug-Sep 2006. Fever with multiple joint pains was the first presenting feature. Aedes larval surveys indicate high Breteau index (78.6 to 200), House index (48.0 to 83.3) & Container index (41.1 to 73.6) above the critical index. Out of 40 sera samples tested, 12 showed HI antibodies for chikungunya virus in high titres and another five were positive for IgM antibodies against chikungunya. The clinico-epidemiological, laboratory and entomological investigations confirm that this episode of fever was due to chikungunya fever. Strengthening and intensification of surveillance along with educating the community were recommended for control of outbreak.

Study on the factors affecting the MDA programme in Kerala state.

The Mass Annual Single dose DEC administration (MDA) was initiated in India from 1997. In Kerala MDA was studied as a pilot project in Alappuzha and Kozhikode District from 2000-04 and the first round of MDA was launched in Kerala covering eleven endemic districts, in March 2005. On evaluation, the drug distribution coverage, compliance, etc. were found to be not satisfactory and a need to elicit the factors for poor performance of MDA is felt essential. The main reasons for poor performance of MDA in Kerala state were the lack of adequate prior information to the target population regarding the importance LF elimination programme and inadequate awareness. The fear of side reactions, antipropagonda, poor IEC activities repeated postponement of programme, insufficient time for mobilisation etc. were the other reasons for poor compliance. The purpose of the present study was to bring the observations to the notice of the authorities so that appropriate remedial measures are incorporated.

Genomic diversity in the regulatory nef gene sequences in Indian isolates of HIV type 1: emergence of a distinct subclade and predicted implications.

The regulatory functional nef gene is known to mediate a cascade of events during pathogenesis in HIV infection. Variability in the nef gene sequences of HIV-1 A and B subtypes has been well documented. Reasonable data are also available on the pattern of genomic changes in the nef gene of African strains of HIV-1 subtype C, but very little is known about heterogeneity in the nef gene of Indian strains of HIV-1 subtype C, which accounts for 90% of the estimated 5.2 million cases of HIV infection in India. This is a huge number and, therefore, it is important to reveal the extent of sequence variability in the nef gene of HIV-1 subtypes circulating in different parts of India. We carried out full-length nef gene (approximately 620 bp) sequencing on a large number of clinical isolates of HIV-1 circulating in different geographic regions of India. Comparative and phylogenetic analysis revealed 88% (38/43) of cases was HIV-1 subtype C; four cases were diagnosed as subtype A and only one as subtype B. Although most of the crucial functional motifs of the nef gene were conserved, we did observe a few important variations in juxtapositions to functional domains. Interestingly, analyzed nef sequences showed an evolving pattern of segregation away from those reported from other parts of the world, to form a distinct Indian subclade. Deduced amino acid (aa) sequences used to predict HLA binding epitopes for consensus nef gene sequences of Indian strains of HIV-1 revealed two HLA subtype binding domains, GAFDLSFFL (at aa 83) and LTFGWCFKL (at aa 136), in high frequency. The findings from the present study may encourage use of nef gene in molecular diagnostics/genotyping, keeping track of the evolutionary trend and pinpointing the emergence of recombinant strains, and in the future, designing a multiepitope HIV vaccine suitable for the Indian population.

Protein antigen b (Pab) based PCR test in diagnosis of pulmonary and extra-pulmonary tuberculosis.

BACKGROUND AND OBJECTIVES: Diagnosis of tuberculosis (TB) is largely based on microscopy and culture examination which are either less sensitive, or time consuming. In the present study a PCR (polymerase chain reaction) test based on DNA sequence coding for a 38-kilodalton protein antigen b (Pab) ,specific for Mycobacterium tuberculosis was compared with Ziehl-Neelsen (ZN) stained AFB (acid fast bacilli) smear examination, culture based on conventional Lowenstein-Jensen (LJ) medium and radiometric BACTEC 460 system for the diagnosis of TB using clinical samples obtained from pulmonary and extra-pulmonary cases of TB. METHODS: Clinical samples obtained from 168 patients of suspected TB (pulmonary and extrapulmonary) were subjected to ZN smear examination, LJ culture, radiometric BACTEC culture and a PCR test by amplifying 419 bp sequence coding for Pab, a glycoprotein of molecular weight 38 kDa. RESULTS: A significant difference was seen in the sensitivity of different tests, the figures being 74.2 per cent for PCR test, 53.4 per cent for BACTEC culture, 47.1 per cent for LJ medium based culture and 35.2 per cent for ZN smear examination (P<0.05). However, there was no significant difference between different tests as far as specificity was concerned. PCR test sensitivity in pulmonary and extra-pulmonary clinical samples were 74.3 and 71.5 per cent respectively, being significantly higher (P<0.05) when compared with sensitivity of other tests. The mean detection time for M. tuberculosis was 24.0 days by LJ media culture, 12.8 days by BACTEC culture and less than 1 day by smear examination and PCR test. INTERPRETATION AND CONCLUSION: PCR test is more sensitive than ZN smear examination, LJ medium culture and BACTEC culture for diagnosing TB in pulmonary and extra-pulmonary clinical samples.