Animal disease surveillance: Its importance & present status in India.

Animal disease surveillance encompasses systematic collection of long-term data on disease events, risk factors and other relevant parameters followed by analyzing the same with reference to temporal and spatial characteristics to arrive at a conclusion so that necessary preventive measures can be taken. In India, the animal disease surveillance is done through National Animal Disease Reporting System, which is a web-based information technology system for disease reporting from States and Union Territories with the aim to record, monitor livestock disease situation and to initiate the preventive and curative action in a swift manner during disease emergencies. National Animal Disease Referral Expert System is a dynamic geographic information system and remote sensing-enabled expert system that captures an incidence of 13 economically important livestock diseases from all over the country and also provides livestock disease forecasting. The laboratories under State and Central governments, several research institutes under the Indian Council of Agricultural Research and veterinary colleges are involved in livestock disease diagnosis including zoonotic diseases. An integrated surveillance system is necessary for early detection of emerging/zoonotic diseases in humans. This review provides information on disease reporting and surveillance systems in animal health sector and the need for One Health approach to improve and strengthen the zoonotic disease surveillance system in India.

Comparative evaluation of nucleic acid-based assays for detection of Japanese encephalitis virus in swine blood samples.

Japanese encephalitis is an emerging mosquito-borne flaviviral zoonotic disease. The present study was undertaken with the objective of developing rapid and sensitive nucleic-acid-based assays for detection of Japanese encephalitis virus (JEV) in swine blood samples. Three nucleic-acid-based assays, viz., reverse transcription polymerase chain reaction (RT-PCR), reverse transcription loop-mediated isothermal amplification (RT-LAMP), and real-time RT-PCR, were developed and compared in terms of their diagnostic efficacy. All three assays were found to be 100 per cent specific. The minimum detection limit of RT-LAMP and real-time RT-PCR was 12 copies/µl, while RT-PCR could detect 1.2 × 10(5) copies/µl. On comparison, RT-LAMP and real-time RT-PCR were 4-log more sensitive than RT-PCR. The applicability of the assays was evaluated by screening 135 field swine blood samples, of which 24 (17.77 %) were positive by RT-LAMP and real-time RT-PCR and only six (4.44 %) were positive by RT-PCR. The viral load in swine blood samples ranged between 2 × 10(6) and 4.8 × 10(9) copies per ml of blood by real-time RT-PCR. The comparative diagnostic sensitivity and specificity of RT-LAMP vis-à-vis real-time RT-PCR was found to be 100 %, while the sensitivity and specificity of RT-PCR vis-à-vis real-time RT-PCR was found to be 25 % and 100 %, respectively. Thus, the use of RT-PCR may cause the incidence of JEV in the swine population to be underestimated, while the real-time RT-PCR reported here is the test of choice for reference laboratories, and the newly developed one-step RT-LAMP assay will be suitable for field-level testing.

Development of recombinant nonstructural 1 protein based indirect enzyme linked immunosorbent assay for sero-surveillance of Japanese encephalitis in swine.

Japanese encephalitis virus (JEV) causes severe neurological disease in humans, especially among children. The disease is endemic in several South Asian countries including India. Swine play a major role as amplifier host for JEV and act as a source of infection to humans through mosquito bite. Early detection of either virus or antibodies in swine will aid to undertake control measures to prevent virus spread to humans. Swine seldom show symptoms of JEV infection and the viraemic phase lasts for a short period of 3 to 4 days indicating the potential of detection of antibodies, which remain for relatively longer period, as a suitable alternative. Cost effective and sensitive assays for the detection of JEV antibodies in swine are not available indigenously. Hence, we have developed a recombinant nonstructural protein 1 (rNS1) based enzyme linked immunosorbent assay for the detection of IgG antibodies against JEV in swine. The test is robust, highly sensitive (91%), specific (97%), reproducible and affordable. Field validation of the assay was done by screening 3628 swine Serum samples collected from different parts of India. The overall sero-positivity was found to be 32.22%. The developed ELISA can be readily incorporated into surveillance programs for detection of Japanese encephalitis virus activity in swine population thereby aiding in prediction of outbreaks in humans.