Clinical and laboratory profile of dengue viral infections in and around Mangalore, India.

BACKGROUND: Dengue (DEN) is being recognised as the world's major emerging tropical disease. Clinically, DEN may resemble other infections such as malaria, leptospirosis, and typhoid, and thus, laboratory investigations are required for definitive diagnosis. Secondary DEN infection, caused most often by dengue virus (DENV) serotypes 2 and 3, is known to present with severe disease manifestations. This study was undertaken to examine the clinical and laboratory profile of DEN viral infections and to determine the circulating serotypes in and around Mangalore, India. MATERIALS AND METHODS: Serum samples from 285 clinically suspected cases of DEN in and around Mangalore between September 2013 and January 2014 were processed for detection of DEN IgM and IgG antibodies and nonstructural 1 (NS1) antigen using commercial ELISA kits. Detection of DEN viral RNA and serotyping was done by multiplex real-time reverse-transcriptase polymerase chain reaction (RT-PCR). The clinical and haematological profiles of the patients were analysed. RESULTS: Serum samples from 83 (29%) patients were positive for DEN NS1 antigen and/or IgM antibodies. 33 (45%) out of 73 serum samples processed by multiplex real-time RT-PCR were positive for DEN viral RNA. DEN-1, -2 and -3 were the serotypes identified in this study. Fever was the most common presenting symptom followed by myalgia/arthralgia. Majority of the patients had thrombocytopaenia. CONCLUSION: Early detection of DEN can be achieved effectively using NS1 ELISA and IgM capture ELISA. Circulating DENV serotypes should be closely monitored for prevention of fatal outcomes in secondary infections.

Evaluation of NS1 Antigen Detection for Early Diagnosis of Dengue in a Tertiary Hospital in Southern India.

INTRODUCTION: Dengue is a mosquito-borne disease affecting mainly tropical and subtropical regions of the world. The early diagnosis of dengue is required for identifying an epidemic and also for implementing effective vector control measures. AIM: To evaluate NS1 antigen assay as an alternative to RT-PCR for the early diagnosis of Dengue. MATERIALS AND METHODS: A comparative study was conducted to evaluate NS1 antigen assay in clinically suspected dengue cases admitted to JIPMER hospital from January to November 2011. Serum samples were tested for NS1 antigen, IgM and IgG antibodies by ELISA and RT-PCR. RESULTS: Out of total 112 clinically suspected dengue, 94 were laboratory-confirmed dengue cases (positive by one or more of the following tests - IgM ELISA, NS1 antigen ELISA and RT-PCR). NS1 was detectable from day 1 to day 12 of fever. The positive detection rate of NS1 antigen ELISA, RT-PCR and IgM ELISA were 80.9%, 68.1% and 47.9% respectively. NS1 antigen ELISA was evaluated using RT-PCR as the reference standard and showed a sensitivity of 96.8%, specificity of 53.3%, positive predictive value of 81.6% and negative predictive value of 88.9% with a likelihood ratio of 2.1 by Fisher's-exact test. The combination of NS1 and IgM had the highest sensitivity of 97.8%. DEN-3 was the serotype identified by RT-PCR for 24 randomly selected samples. NS1 antigen detection had the highest sensitivity in the early stages while IgM detection was more sensitive in the later half of the illness. CONCLUSION: Both NS1 and RT-PCR are useful for early dengue diagnosis, although in terms of cost, ease of performance and rapidity, NS1 is superior to RT-PCR. NS1 in combination with IgM assay offers the most sensitive and cost-effective diagnostic modality for dengue.

Human rabies in India: an audit from a rabies diagnostic laboratory.

OBJECTIVES: Rabies, an acute progressive encephalomyelitis, continues to be a serious public health problem in India and many other countries in Asia and Africa. The low level of commitment to rabies control is partly attributable to challenges in laboratory diagnosis and lack of adequate surveillance to indicate the disease burden. A laboratory audit of human rabies cases was undertaken to disseminate information on the clinical, demographic, prophylactic and most importantly the laboratory diagnostic aspects of rabies. METHODS: A retrospective analysis of all clinically suspected human rabies cases, whose samples were received at a rabies diagnostic laboratory in South India in the last 3 years, was performed. Clinical and demographic details of patients were obtained. The clinical samples included cerebrospinal fluid (CSF), serum, saliva and nuchal skin biopsy collected antemortem, and brain tissue obtained post-mortem. Various laboratory tests were performed for diagnosis. RESULTS: Clinical samples from 128 patients with suspected rabies, from 11 states in India, were received for diagnostic confirmation. About 94% of the victims reported dog-bites, more than a third of them were children and most of the victims did not receive adequate post-exposure prophylaxis. Antemortem confirmation of rabies by a combination of laboratory diagnostic assays (detection of viral RNA in CSF, skin and saliva, and neutralising antibodies in CSF) could be achieved in 40.6% cases. CONCLUSIONS: Increasing awareness about adequate post-exposure prophylaxis, additional rabies diagnostic facilities, and enhanced human and animal rabies surveillance to indicate the true disease burden are essential to control this fatal disease.

Natural Rabies Infection in a Domestic Fowl (Gallus domesticus): A Report from India.

BACKGROUND: Rabies is a fatal encephalitis caused by viruses belonging to the genus Lyssavirus of the family Rhabdoviridae. It is a viral disease primarily affecting mammals, though all warm blooded animals are susceptible. Experimental rabies virus infection in birds has been reported, but naturally occurring infection of birds has been documented very rarely. PRINCIPAL FINDINGS: The carcass of a domestic fowl (Gallus domesticus), which had been bitten by a stray dog one month back, was brought to the rabies diagnostic laboratory. A necropsy was performed and the brain tissue obtained was subjected to laboratory tests for rabies. The brain tissue was positive for rabies viral antigens by fluorescent antibody test (FAT) confirming a diagnosis of rabies. Phylogenetic analysis based on nucleoprotein gene sequencing revealed that the rabies virus strain from the domestic fowl belonged to a distinct and relatively rare Indian subcontinent lineage. SIGNIFICANCE: This case of naturally acquired rabies infection in a bird species, Gallus domesticus, being reported for the first time in India, was identified from an area which has a significant stray dog population and is highly endemic for canine rabies. It indicates that spill over of infection even to an unusual host is possible in highly endemic areas. Lack of any clinical signs, and fewer opportunities for diagnostic laboratory testing of suspected rabies in birds, may be the reason for disease in these species being undiagnosed and probably under-reported. Butchering and handling of rabies virus- infected poultry may pose a potential exposure risk.

Comparison of safety and immunogenicity of 2 WHO prequalified rabies vaccines administered by one week, 4 site intra dermal regimen (4-4-4-0-0) in animal bite cases.

The currently advocated rabies post-exposure prophylaxis regimens are of one month duration with reduced patient compliance. WHO recommended research on shortened vaccination regimens which have a practical and economic advantage over the existing regimens. Hence, the present study was undertaken to assess the safety and immunogenicity of 2 WHO prequalified rabies vaccines administered by one week, 4 site intra dermal regimen (4-4-4-0-0) in animal bite cases. This study was a comparative, open label, phase III, randomized clinical trial conducted at Anti rabies clinic, KIMS Hospital, Bangalore, India. The study was registered in Clinical Trials Registry of India (CTRI) bearing the registration number CTRI/2012/12/003230. Ninety subjects with category II/III animal bites/exposures were enrolled. Equine rabies immunoglobulin was administered to all category III exposures. 0.1 mL of either purified chick embryo cell vaccine (Rabipur) or purified verocell rabies vaccine (Verorab) was administered intradermally into 4 sites on days 0, 3 and 7 to all the study subjects. Serum of subjects collected on day 0, 14, 90 and 365 were analyzed for rabies virus neutralizing antibody (RVNA) concentration. The incidence of ADR in Rabipur and Verorab group was 2.96% and 1.14% respectively. In Rabipur group, geometric mean concentration (95% confidence interval) of RVNA was 14.5 (13.50, 15.57), 11.78 (11.27, 12.31) and 5.95 (5.50, 6.44) IU/mL on days 14, 90 and 365 respectively; In Verorab group geometric mean concentration (95% confidence interval) of RVNA was 14.43 (13.41, 15.53), 11.93 (11.47, 12.40) and 5.67 (5.29, 6.08) IU/mL on days 14, 90 and 365 respectively. In conclusion, Rabipur and Verorab were found to be safe, immunogenic and comparable with each other, when administered using one week, 4 site intradermal regimen (4-4-4-0-0) in animal bite cases.

Atypical rabies encephalitis in a six-year-old boy: clinical, radiological, and laboratory findings.

A 6-year-old boy from India developed an atypical form of rabies following a stray dog bite and as a consequence of not receiving the standard World Health Organization recommended post-exposure prophylaxis for category III wounds. Serial rising rabies virus neutralizing antibody titres in serum and cerebrospinal fluid by rapid fluorescent focus inhibition test helped confirm the diagnosis of rabies. The child has survived for 4 months since the onset of illness, albeit with neurological sequelae.