This rains, beware of zika along with dengue and chikungunya

To begin with, all state governments must release an immediate advisory on diagnosis, treatment and prevention to healthcare providers.

Sheetal Ranganathan



Our house smells pleasurably different this morning. Wafts of strong coffee mixed with whiffs of golden-fried vegetable fritters – they tell me it is that time of the year again. These magical moments make my body and spirit buzz with excitement. Bye-bye, scorching sun. Welcome, water of life. Is there anything more energising than waking up to the music and scents of rain?

I feel good. As good as the human inhabitants of my house. Time to grab a quick bite before my little rascals wake up. “Larvae, pupae, sleep some more, my darlings. Mum will be back in no time after her breakfast.”

Which human shall I choose today? That one, in blue vest, with legs and arms dangling out of that wretched bed-net. Yes, that’s the one – safe and easy catch for a stomach full of blood meal. Slurp.

Delivered the viral load, and earned my grub. Done with the business of the day in a shot. No monstrous teeth, poisonous fangs or colossal strength, a gentle pierce is all it takes to be number one on the list of the most dangerous animals compiled by humans. It’s a mosquito’s life. I love my life.

Heard that we’ll have new ammunition this monsoon, the one that made my South American cousins infallible. The long-pending virus cargo has arrived at India’s western port. May our ferocity grow. May our tribe flourish. May my swarm stay abuzz with many more little Aedes aegypti.

Some people feel the rain. Others just get wet. Far too many fall sick.

The much-awaited monsoon has arrived. Of mercurial weather swings and associated mood swings. When the wind blowing through India’s cities and villages carries excess moisture, a spectrum of smells, and along with it the scourge of mosquitoes.

At once, one may be enchanted with the scents of fragrant-earth and tranquil-chai; or dampened by the reeking odour of nauseating-sewage rot and mosquitocide-laced diesel fog. At once, one may be uplifted into ecstasy by cheerful showers and waltzing trees; or pulled into a pothole of haplessness by a list of mood and body cinchers – traffic jams, tarpaulin-wrapped homeless, dengue, chikungunya among others. The monsoon menace list of the year 2017 has a new entrant, zika.

Earlier this month, news of the first three laboratory-confirmed casesof zika virus infection in India broke from Bapunagar district of Ahmedabad. The first was identified in November 2016, just nine months after India’s health minister had tweeted that there were no cases of zika in India.

In less than a year, India’s status has downgraded from being a zika-free country (WHO Category 4) to one with confirmed ongoing transmission (WHO Category 2). If not interrupted immediately with adequate screening and control measures, zika may match or surpass the speed at which dengue and chikungunya have become endemic to India in the last five years.

mosquitoes_070317094228.jpgThe long-pending virus cargo has arrived at India’s western port. Photo: Reuters

All three are viral diseases, spread by the bite of the same mosquito type. That of Aedes aegypti, commonly identified as mosquitoes with spotted legs. They are aggressive dawn and dusk hunters.

The zika virus is here. Should there be panic or alarm? The health minister of Gujarat confirmed no transmission so far, which is reassuring and at the same time a warning bell to tighten surveillance.

The situation may fast take a worrying turn if one were to simply extrapolate the disease transmission trend of dengue and chikungunya in India on zika’s spread. Field studies from the Pacific region tracking simultaneous outbreaks of these three viruses have shown that zika’s spread roughly follows the pattern of dengue outbreak progression in the same ecological setting.

In that context, it is important to note that dengue cases have grown by seven times and those of chikungunya have almost tripled in India since 2011.

Despite active control measures in action, dengue cases have shown a disturbingly high annual growth rate of 47 per cent in the last five years.

It is scary if one were to assume that zika would follow its course as that in Brazil and Puerto Rico, wherein the outbreak assumed epidemic proportions within less than two years of identification of the first reported cases. Based on the disease transmission routes and attack rates seen in other countries that saw the zika epidemic between 2014 and 2016, elaborate mathematical models are now available to simulate spread scenarios for zika in India.

Whatever be the space-time graph of zika transmission that emerges in years to come, the story that will unfold in parallel will be tragic. A recent study published in Lancet Infectious Diseases (November 2016) has estimated 90 per cent residents of India to be susceptible to zika exposure at the time of peak seasonal risk.

Clinically, the zika infection manifests itself with symptoms overlapping, yet several notches milder than those presented by the bone-breaking dengue and chikungunya. Low-grade fever with mild muscle pain and rash are the common symptoms of zika fever. Many cases of zika infection may go undetected in the garb of seasonal flu or dengue or chikungunya, if not tested. Pregnant women face the highest risk, with terrible consequences.

If infected, their babies may be born with neurodegenerative disorders, microcephaly (collapsed or deformed head), and other birth defects. For a country where 50 babies are born per minute, a zika outbreak will bring forth an unfortunate calamity for families in India.

Easy come, not easy go

zika’s entry in to India is hardly surprising. It was just a matter of time. In 2016, India received in excess of 8.5 million foreign tourists. 67,400of these foreign guests arrived into India from countries falling in the ecological niche of zika virus in the Americas – any one of these tourists could have in-sourced the virus.

Ready or not, with a combination of socio-economic and ecological factors that are favourable to zika transmission, India now stands vulnerable. The presence of abundant populations of a competent vector in female Aedes aegypti, and a climate conducive for mosquitoes to survive long enough for zika virus to incubate together make a strong case for year-round transmission, following the spatio-temporal pattern seen for dengue and chikungunya menace within the country.

Having known the imminent risk, it was shocking to see a five-month delay on a public announcement of the Ahmedabad findings by the Union health ministry. Moreover, the local municipal authorities were kept uninformed, and a surveillance activity was run masked under the ongoing malaria-free pilot project of Gujarat.

Media and public condemnation came in plenty, and deservedly so. One month on, the government continues to be in a semi-complacent mode on this matter.

Since May-end, zika screening has been rightfully extended to more districts of Ahmedabad, albeit in stealth mode. According to a DNAreport, the community health staff of five districts – Anand, Baroda, Kheda, Mehsana, Sabarkantha – have been involved in zika surveillance, while being told that it is for malaria.

A stitch in time will make zika toe the line

India is fortunate to have detected zika in time. The socio-economic impact of what became a public health emergency for several countries of the world can be mitigated by India. zika made Brazil, Columbia and Suriname suffer a collective socio-economic cost of USD 7-18 billion.

India can avoid a misery of that scale and order. All it needs is timely and widespread action, as outlined below. The government and the community have to work in tandem for successful implementation.

  1. All state governments must release an immediate advisory on diagnosis, treatment and prevention to healthcare providers.
  2. For the general public, the ongoing communication efforts about dengue and chikungunya must be tweaked to include risk zika risk messaging.
  3. All cases of dengue and chikungunya in expecting mothers and her immediate family must be tested for zika virus co-infection.
  4. More importantly, diagnostic labs across the country need be prepared to offer zika-detection tests. Currently, this facility is available (RT-PCR test) at two sites in the entire country – the National Institute of Virology in Pune, and National Centre for Disease Control in Delhi. The Indian Council of Medical Research is working towards getting an additional 25 laboratories ready for zika virus detection.
  5. The zika virus strain isolated from Ahmedabad must be investigated further. Viruses are masters of deceit. They mutate often to change their characteristics. For example, the zika virus type found in Singapore is not the same as the one that caused havoc in Brazil, proving that it was not imported from Brazil into Singapore.

Such observations become the essential foundation of research to develop vaccines, detection techniques and anti-viral treatment options



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