In the light of Zika virus cases in Kerala, the Directorate of Public Health (DPH) and Preventive Medicine has taken up surveillance in areas bordering Kerala. As part of the monitoring, 65 Aedes mosquito pools collected from areas bordering Kerala were tested at the State Public Health Laboratory (SPHL). All pools were found to be negative for Zika virus.
According to the Directorate, Zika virus is transmitted by the Aedes mosquitoes that also transmits dengue, chikungunya and yellow fever. Recently, cases of Zika virus were reported in Kerala, and as of July 12, 18 cases are documented. RT-PCR test was the method of choice for confirmation of Zika virus, in which serum samples are collected during the first five days after the onset of symptoms.
The SPHL is an Indian Council of Medical Research approved RT-PCR laboratory for COVID-19 testing in Tamil Nadu, handling a sample load of 7,000-8,000 samples a day. SPHL has the capacity for the surveillance and diagnosis of vector borne diseases such as dengue, Japanese encephalitis and Zika from human samples and mosquito samples from the field by RT-PCR method. The facility currently has Zika-specific RT-PCR test kits, and human samples as well as mosquito pools can be tested for Zika virus for laboratory confirmation, a report issued by the DPH on Zika Virus Surveillance and Diagnostic Capacity in Tamil Nadu said.
SPHL tested a total of 65 Ades mosquito pools collected from bordering areas of Kerala and all pools were negative for Zika virus. Detection of arboviruses such as dengue, Japanese encephalitis and Zika from the mosquitoes caught from the field by RT-PCR method is being used as a potential surveillance tool for the prevention and control of vector-borne diseases. This activity was “innovative and unique for Tamil Nadu under Vector Borne Disease Control programme”, it said.
In Chennai, officials said that the ongoing measures for dengue control should help in monitoring Zika virus as well. “Both are caused by the same species, Aedes. So, dengue control measures are adequate to keep watch for Zika. We are taking dengue control measures on a war-footing and are very cautious,” an officer of the Greater Chennai Corporation said.
He said a total of 2,080 domestic breeding checkers were deployed to take up regular checks on a daily basis. “In the meantime, we are taking up frequent source reduction measures. The intermittent rains lead to the flaring up of mosquito breeding sites. We already have dengue hotspots. We are taking up random checks for adult Aedes density as well. If the density is high, we are stepping up anti-larval measures such as fogging,” he explained.
The official said the aim was to control dengue cases as last year there were 100-odd cases in the city, while in the previous two years, the number of cases were in four digits.
