The Zika Virus

Information sharing and transparency on the government’s part is critical to preempt a Zika outbreak in India.

WrittenBy:Science Desk
Article image

By Swetha Godavarthi and Sudheendra Rao N R

In an online bulletin, posted on May 26, 2017, World Health Organisation (WHO) shared Ministry of Health and Family Welfare’s (MoHFW) report of three confirmed cases of Zika virus in Gujarat. In two of the cases, samples were collected under routine surveillance, while in the third case sample was collected in response to the fever’s symptoms seen in the patient. The samples tested positive for the virus when they were put through a viral genome detection test at the BJ Medical College, Ahmedabad, and National Institute of Virology, Pune, between January  and February 2017.

First isolated from a rhesus monkey in the Ziika forest of Uganda in 1947, the Zika virus is a single-stranded RNA virus from the Flaviviridae family. It is related to the yellow fever, West Nile, dengue and Japanese encephalitis viruses. As with dengue and chikungunya, carrier female Aedes mosquitoes infect humans through their bites, which can then be transmitted between humans through mosquito bites. Zika virus can also be transmitted through sexual intercourse, maternal-foetus transmission and transfusion of infected blood.

Zika virus outbreaks have been reported in several parts of the worldAfrica, Western Pacific and Americas. Majority (80%) of the affected individuals do not show any symptoms, and a few of them develop mild symptoms of fever, skin rash, body pain, joint pain and conjunctivitis. However, it was the major outbreak in Brazil in 2015 affecting almost 1.3 million people, subsequently spreading to 33 different countries that drew global attention. The virus had undergone some changes,affecting foetuses and adults. The infection was now also associated with congenital brain abnormalities, like microcephaly (smaller than normal head, which in turn causes several neurological complications like intellectual disability) and could trigger the potentially life-threatening Guillain-Barré syndrome (GBS), wherein the immune system attacks the peripheral nervous system, causing rapid onset of muscle weakness and paralysis  in children and adults.

Currently, there are no vaccines or antiviral drugs to combat Zika. The treatment is essentially symptomatic – rest, remaining hydrated and paracetamol to control fever and pain. However, a few vaccines under development are now entering Phase 1 of clinical trials, including one developed in India by Bharat Biotech.

In February 2016, in the first meeting of WHO’s Emergency Committee (EC), it was recommended that cases of Zika virus and associated neurological disorders constitute a Public Health Emergency of International Concern. India has been screening for Zika in individuals and mosquitoes since July 2016, at 50 different laboratories across the nation. The first case of Zika infection was confirmed in the laboratory on January 4, 2017. MoHFW communicated the detection of 3 cases to WHO on 15 May 2017, a delay of 4 months from first confirmation. According to a report in, the local health authorities in Ahmedabad, who are responsible for disease prevention and control measures, learnt about the Zika cases from WHO website, and surprisingly not from the government directly. Many public health experts and activists say the government should not have delayed informing WHO, while the government insists that it wanted to screen further before releasing the information. According to the government press release, they have since tested thousands of samples, none of which have tested positive for the virus. Irrespective of whether government stepped-up surveillance following confirmation (which according to Gujarat health commissioner was done without even informing people that they were being tested for Zika), the information should have been shared with health officials and the public. The means of controlling panic among public is not lack of information, but sharing information clearly, so that local bodies and individuals can take appropriate protective measures. It is the right of the individual to know what their biological samples are being used for and what the outcome of such an analysis is.

The only other report of Zika’s possible presence in India was back in 1954, in parts of then Bombay, Saurashtra and Nagpur.

imageby :
imageby :

Now, 63 years later we have 3 new cases of Zika. Given that the currently affected individuals did not travel outside (prior to onset of symptoms), they could not have contracted the disease elsewhere. Thus it is important to trace how the individuals contracted the infection, as has been done by countries during the 2015-2016 Zika outbreak.

Interestingly, the three affected individuals while being unrelated, belong to the same district. This potentially suggests that the virus could be restricted to the region. In this light, the government report stating sampling of 16,571 mosquitoes and 36,613 human subjects, and finding none positive, seems to be missing crucial details.

For example, it is important to know how many of the mosquitoes tested were actually from the carrier—Aedes genus? Were these samples collected from the affected district alone or from different parts of the country? Sharing such details especially with scientists and public health officials, will help us to be prepared and better combat any outbreak in the future.

While it is important to know the number of people infected with Zika virus, it is perhaps more essential to ascertain the percentage of Aedes mosquitoes carrying the virus, as they are the primary transmission agents. This would provide us with a better understanding of the spread of disease in the population.

The National Vector Borne Disease Control Programme (NVBDCP), which has been set up to control and prevent vector borne diseases like malaria, Dengue, Chikungunya and Zika should be more forthcoming and make its vector surveillance data public. NVBDCP should provide information like – how much fogging is being done? What is being used for fogging? Are they seeing any chemical-resistant mosquitoes in the fogged area? Are samples collected before and after fogging? Is there any overlap between dengue and Zika affected areas? Easy to understand maps with GPS/IRNSS coordinates would be a good tool to use by them to communicate these data. Most of the times when we talk about Zika (or other infections), we focus on what needs to be done from the patient side, and about public education and guidelines. In addition, it is also important to understand the efficacy of our vector control program.

Given that the Aedes bites during the day, mosquito nets are of little use to combat them. Fogging effects are short-lived and can indeed lead to a rise in fogging-chemical resistant mosquito population.

There are newer methods of vector control and surveillance that need to be actively explored by the NVBDCP and effectively communicated to the public. For example, India recently joined Australia led ELIMINATE Dengue Project. Wolbachia is a bacteria which infects a lot of insects. ELIMINATE project aims to use Wolbachia bacteria to infect Aedes mosquitoes in dengue areas and render them incapable of disseminating dengue and chikungunya viruses. A recent scientific paper in the journal Cell has reported that the same is true for Zika virus as well.

Another innovative approach is based on pyriproxyfen, a human-safe synthetic analogue of mosquito juvenile hormone, that female mosquitoes can themselves deliver to the larva, thus overcoming the limitations of search for breeding containers that are often unreachable to eliminate larval population. Release of sterile male mosquitoes to decrease the overall mosquito population is another approach. Yet another strategy is release of genetically-modified mosquitoes maintained on specific drugs (e.g. tetracycline) in the laboratory. When released, the mosquitos breed but offspring can not survive since the specific drug is absent from the environment. All the above approaches are being tested in various countries around the world and can produce dramatic (nearly 95%) reduction in the mosquito population.

While it is important for people to follow precautions to protect themselves and their loved ones from mosquito bites (mosquito nets, mosquito repellents and creams), it is equally important for them to maintain cleanliness at home and in their surroundings. However, with rapid urbanisation and constantly shifting personal and governmental priorities, vector control programmes need to be strengthened to allow innovative out-of-the-box approaches. Active governmental participation through policy decisions and proactive promotion can substantially affect our responses to various vector borne diseases plaguing India, including Zika.

The authors want to acknowledge Ajit Ray for his inputs.

Sudheendra Rao is a doctor-scientist interested in science, innovation and health policy paradigms in India. He is currently a post-doctoral associate at The Miami Project to Cure Paralysis, University of Miami, Florida, USA.


We take comments from subscribers only!  Subscribe now to post comments! 
Already a subscriber?  Login

You may also like