Seven Zika Cases in Pune Highlight India’s Testing Challenges, Say Experts

Experts warn that infections may go undetected unless diagnostic tests are improved.

PUNE: The sudden appearance of seven Zika virus cases in Pune has raised alarms among top virologists. They are concerned about “critical gaps” in India’s ability to detect and monitor this mosquito-borne disease. Experts who spoke to TOI believe the virus might be “silently spreading” across the country, with only a few labs capable of confirming infections.

“India’s limited testing capacity for Zika is a major concern,” said Dr. Vinod Scaria, a virologist known for detecting the Delta variant of Covid-19. “Only a select few laboratories, including the National Institute of Virology (NIV) in Pune, can perform Zika diagnostic tests. There are no diagnostics approved by the Central Drugs Standard Control Organization (CDSCO) for wider use by other labs to identify Zika. This means we’re likely recording just a fraction of the actual cases. The lack of widespread testing and surveillance is particularly worrying given the risks Zika poses to pregnant women,” he added.

For diagnostics to be quickly developed and widely accessible, Dr. Scaria emphasized the need for whole genome sequences from outbreaks to be made available in public databases.

Dr. Rajalakshmi A, an infectious disease specialist at KIMSHEALTH in Thiruvananthapuram and a co-investigator in Kerala’s first Zika outbreak in 2021, said, “Proactive surveillance is necessary to understand the prevalence and pattern of Zika virus disease (ZVD). In Indian outbreaks, we have limited information about ZVD in pregnancy. No increase in microcephaly was reported in previous Indian outbreaks. Surveillance in pregnant women for ZVD and fetal abnormalities, and in newborns for congenital abnormalities, is lacking in India.”

Senior virologist Shahid Jameel questioned, “If the Indian Council of Medical Research (ICMR) detected Zika-positive Aedes mosquitoes, what has it done to track its movement into humans? We need a syndromic surveillance plan, use available PCR tests when needed, and alert hospitals in vulnerable areas. Test development must be taken up, but it won’t help in this season.”

Experts pointed out that the diagnostic gap, combined with Zika’s similarity to dengue symptoms, means many cases might go undetected. They noted that the CDSCO had earlier confirmed no approved Zika test is currently available for widespread use in India. This diagnostic gap is further complicated by India being endemic to dengue and chikungunya, other major vector-borne viral diseases transmitted by the Aedes mosquito, the same vector transmitting Zika. Moreover, some symptoms overlap among these diseases. Unless diagnostic tests are strengthened, many ZVD cases may go undiagnosed.

Dr. Rajalakshmi mentioned that many ZVD cases were likely missed due to mild symptoms, limited PCR testing, and availability. Both clinicians and patients should be alerted to the possibility of Zika when a patient presents with fever, joint pain, itchy rash, and red eye, as these symptoms might be dismissed as other viral fever or allergy. “Regular surveillance would help us understand seasonal patterns, assess the true disease burden, and guide public health measures like vector control,” she said.

A senior official from the National Centre for Disease Control (NCDC) stated that there is no question of inadequate surveillance for the Zika virus. “We have a dedicated National Center for Vector Borne Diseases Control program division. It oversees mosquito control measures.” When asked about the limited availability of Zika tests, the official acknowledged, “Yes, that’s an issue. At present, Zika testing is primarily conducted in select laboratories.”