India / Cat Que Virus from China has the potential to cause disease in India: ICMR

NEW DELHI: Even as India grapples with the SARS CoV-2 virus causing covid-19, scientists at the Indian Council of Medical Research (ICMR) have found another virus -- cat que virus -- largely reported in China and having the potential to cause disease in the country.

One of the arthropod-borne viruses (arboviruses), CQV can cause febrile illnesses, meningitis and paediatric encephalitis in humans. The presence of cat que virus (CQV) in culex mosquitoes and pigs has been reported in China and Vietnam.

Considering the spread of similar species of culex mosquitoes in India, scientists at National Institute of Virology (NIV) ICMR, Pune have found antibodies for the virus in two of the 883 human serum samples tested from across states in India, indicating that the persons had at some point of time contracted the infection. However, the virus was not found in any of the human or animal samples at the time of study. Antibodies are formed by the immune system of humans when a virus attacks the body.

The two human samples that were found to be positive for the presence of anti-CQV IgG antibodies were from Karnataka in 2014 and 2017 respectively.

“Anti-CQV IgG antibody positivity in human serum samples tested and the replication capability of CQV in mosquitoes indicated a possible disease causing potential of CQV in Indian scenario. Screening of more human and swine serum samples using these assays is required as a proactive measure for understanding the prevalence of this neglected tropical virus," said the ICMR. The findings of the study have been published in the latest issue of Indian Journal of Medical Research (IJMR).

Availability of vector, primary mammalian host (swine) and confirmation of CQV from jungle myna signifies the potential of this orthobunyavirus as a public health pathogen in India, ICMR scientists. This led them to develop molecular and serological tests for CQV, screening of host population (human and swine) and its replication kinetics in mosquitoes as part of preparedness against the likely emergence of CQV.

Scientists did susceptibility and replication kinetics experiment using three different species of mosquitoes to understand its behaviour in Indian mosquitoes.

“Data showed that Indian mosquitoes (Ae. aegypti, Cx. quinquefasciatus and Cx. tritaeniorhynchus) were susceptible to CQV," the ICMR study said.

According to ICMR, CQV has been isolated and reported from its natural host, mosquito (culex tritaeniorhynchus), but the role of birds as a host or vector for CQV transmission and report of human infection with CQV are not documented. Domestic pigs are the primary mammalian host of CQV and antibodies against the virus have been reported in swine reared locally in China, indicating that CQV has formed a natural cycle in local areas.