RESUMEN
OBJECTIVE: To identify the aetiological agent/s of an outbreak of chikungunya-like illness with high morbidity and several fatalities in Tamil Nadu, India, 2009-2010. METHODS: Two hundred and seventeen serum samples were collected from the affected areas and screened for chikungunya virus (CHIKV), dengue virus (DENV) and Japanese encephalitis virus (JEV) IgM antibodies using MAC-ELISA kits. A few selected samples were also tested for Ross River, Sindbis, and Murrey Valley viruses by RT-PCR and Hantan virus by serology. Twelve acute serum and mosquito samples were processed for virus isolation in C6/36 cells. CHIKV isolate was characterised by RT-PCR and sequencing. RESULTS: Diagnostic levels of IgM antibodies were detected in 107 (49.3%) CHIKV samples and 22 (10.1%) DENV samples. IgM antibodies against JEV were not detected (n=46). Characterisation of the CHIKV isolate at genetic level demonstrated it as ECSA (E1: 226A). Thirty-six selected samples were also negative for Ross River, Sindbis, Murrey Valley and Hantan viruses. CONCLUSION: High prevalence of CHIKV IgM antibody positivity, clinical symptoms, virus isolation and the presence of vector mosquitoes clearly suggest CHIKV as the aetiological agent responsible for the outbreak.
Asunto(s)
Infecciones por Alphavirus/diagnóstico , Virus Chikungunya/aislamiento & purificación , Adolescente , Adulto , Distribución por Edad , Infecciones por Alphavirus/epidemiología , Infecciones por Alphavirus/transmisión , Animales , Anticuerpos Antivirales/sangre , Virus Chikungunya/inmunología , Niño , Dengue/diagnóstico , Diagnóstico Diferencial , Brotes de Enfermedades , Encefalitis Japonesa/diagnóstico , Femenino , Humanos , Inmunoglobulina M/sangre , India/epidemiología , Insectos Vectores/parasitología , Masculino , Persona de Mediana Edad , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa/métodos , Adulto JovenRESUMEN
BACKGROUND & OBJECTIVES: Chikungunya (CHIK) virus has caused numerous large outbreaks in India. No active or passive surveillance has been carried out since the last epidemic which occurred in 1971. For active surveillance, it is necessary to have a test, which can detect the virus from a large number of field-collected mosquitoes. METHODS: The present study describes the standardization of monoclonal antibody (MAb) based antigen capture ELISA to detect chikungunya virus antigen from the mosquitoes. CHIK virus antigen from suspension of experimentally infected mosquitoes and their progeny was captured on mouse polyclonal antibody, while biotinylated CHIK Mab was used as a probing antibody. CHIK virus antigen in the head squashes of virus inoculated mosquitoes was detected using indirect immunofluorescence antibody (IFA) test for confirmation of ELISA results. RESULTS: The ELISA test was sensitive enough to detect antigen even if a small fraction of a single infected mosquito homogenate was incorporated in the test. The IFA test failed to detect CHIK antigen in 10 and 25 microliters of suspension whereas with ELISA it was detected in all the samples. Progeny of Aedes aegypti and Ae. albopictus mosquitoes infected with chikungunya virus did not show the possibility of existence of transovarial transmission. INTERPRETATION & CONCLUSION: This test is rapid and simple since it can be completed in two days as compared to the conventional mosquito inoculation and IFA techniques, which require at least 10 days. There is an additional advantage with this test that a large number of samples can be processed, and the remaining homogenate of the mosquitoes can be used for screening other viruses. Experimental data raised using this test showed that transovarial transmission of this virus does not occur in these vector species.
Asunto(s)
Aedes/inmunología , Aedes/virología , Anticuerpos Monoclonales , Antígenos Virales/análisis , Virus Chikungunya/inmunología , Ensayo de Inmunoadsorción Enzimática/métodos , Animales , Femenino , RatonesRESUMEN
Chikungunya (CHIK) virus is prevalent throughout Southeast Asia and Africa. It has caused numerous large outbreaks in India. No active or passive surveillance has been carried out since the last epidemic occurring in 1971. During a recent outbreak of Dengue (DEN)-like illness in eastern India, Aedes aegypti mosquitoes collected from the affected area were positive for CHIK virus. Evidence of dual infection with CHIK and DEN typel virus was also obtained. A widely circulating low-virulent CHIK virus is a possible explanation for the epidemiological pattern of the CHIK virus disease in this region.