Can rapid dengue diagnostic kits be trusted? A comparative study of commercially available rapid kits for serodiagnosis of dengue fever

BACKGROUND: Dengue virus infection is an important emerging disease of the tropical and subtropical regions and is mainly diagnosed by serological detection of NS1 antigen and IgM antidengue antibodies. Since enzyme-linked immunosorbent assay (ELISA) facilities are not easily available at most diagnostic centers, so most of them use various commercially available rapid diagnostic tests (RDTs) kits. AIMS AND OBJECTIVES: This study was designed to access the diagnostic accuracy of four commercially available and widely used RDTs for serodiagnosis of dengue virus infection in Indian laboratories. SUBJECTS AND METHODS: The study was conducted at Department of Microbiology, G.S.V.M Medical College, Kanpur, India, to estimate the sensitivity and specificity of following RDTs: (1) Dengue Cassette (Panbio, Australia), (2) Bioline Dengue Duo (SD Diagnostics, Korea), (3) Dengue Day 1 test (J Mitra and Co., India), and (4) Dengucheck Duo (Tulip Diagnostics, India) on 72 confirmed dengue serum samples that were positive by dengue reverse transcription-polymerase chain reaction, dengue NS1, and IgM ELISA along with 80 serum samples from nondengue febrile illness patients. RESULTS: The majority of the RDTs demonstrated low sensitivity but good specificity for detecting NS1 antigen. Detection of antidengue IgM antibodies by RDTs demonstrated low sensitivity ranging from 27.8% to 77.7%. However, specificity was generally higher (50%–86.2%) and more consistent across the assays. CONCLUSION: The study results differed markedly from the RDTs manufacturers’ claimed performance characteristics. Therefore, the RDT results should be interpreted cautiously and ELISA should be performed as far as possible for serodiagnosis of dengue virus infection

Progression of chronic pulmonary tuberculosis in mice intravenously infected with ethambutol resistant Mycobacterium tuberculosis

Purpose: Ethambutol (EMB) is an important first line drug, however little information on its molecular mechanism of resistance and pathogenicity of resistant isolates is available. Present work was designed to study virulence of the EMB resistant M. tuberculosis strains and the host responses in-vivo on infection of EMB resistant M. tuberculosis using Balb/c mouse model of infection. Methods: Three groups of Balb/c mice (female, age 4-6 wk; 21 mice in each group) were infected intravenously with 106 CFU of M. tuberculosis H37Rv and two EMB resistant clinical isolates. Age and sex matched control animals were mock inoculated with Middlebrook 7H9 broth alone. At 10, 20, 30, 40, 50, 60, and 70 days post-infection three animals from each group were sacrificed by cervical dislocation and lung tissue was collected for further analysis. Results: Infection with EMB resistant M. tuberculosis led to progressive and chronic disease with significantly high bacillary load (p=0.02). Massive infiltration and exacerbated lung pathology with increased expression of IFN-γ and TNF-α was observed in lungs of mice infected with EMB resistant strains. The present study suggests that infection with EMB resistant M. tuberculosis leads to chronic infection with subsequent loss of lung function, bacterial persistence with elevated expression of TNF-α resulting in increased lung pathology. Conclusion: These findings highlight that EMB resistant M. tuberculosis regulates host immune response differentially and its pathogenicity is different from drug sensitive strains of M. tuberculosis

Profile of Seropositives Visiting a HIV Screening Centre of a Tertiary Care Teaching Institute in North India

Background: In the era of declining HIV/AIDS prevalence, low penetration of Information Education and Counseling (IEC) activities, particularly among the rural community is still a matter of concern for public health officials. Integrated Counseling and Testing Centers (ICTC’s) are key entry points for a wide range of interventions in HIV awareness, prevention and care in India. Objective: The objective of current study was to assess the socio-demographic profile and risk behavior of attendees who tested seropositive at our ICTC clinic. Methodology: A prospective questionnaire based study from August 2009 to December 2013 was conducted in the ICTC attached to Microbiology department of SGPGIMS to enumerate the socio-demographic and risk behavior pattern of HIV positive cases. Result: Among 16038 attendees investigated during the study, 298(1.86%) tested positive for HIV with a male to female ratio of 2.24:1. Maximum seropositivity (35.6%) was found in the age group of 31-40 years followed by 21-30 years age group (26.8%). Most of the study individuals were married (86.6%) and belonged to rural community. Unprotected heterosexual route was found to be the commonest (71.1%) mode of infection. The majority of the subjects had received education up to primary (36.2%) and secondary level (31.9%). Conclusion: The rural population and the sexually active and economically productive age group dominated among the HIV seropositives presenting at this centre. Heterosexual route is still the predominant mode of transmission among seropositives. Recommendation: The planning and designing of IEC activities should be based on socio-demographic profile and risk behavior pattern of a particular area