On 15 May 2017, the Ministry of Health and Family Welfare-Government of India (MoHFW) reported three laboratory-confirmed cases of Zika virus disease in Bapunagar area, Ahmedabad District, Gujarat, State, India.
The routine laboratory surveillance detected a laboratory-confirmed case of Zika virus disease through RT-PCR test at B.J. Medical College, Ahmedabad, Gujarat. The etiology of this case has been further confirmed through a positive RT-PCR test and sequencing at the national reference laboratory, National Institute of Virology (NIV), Pune on 4 January 2017 (case 2, below). Two additional cases (case 1 and case 3), have then been identified through the Acute Febrile Illness (AFI) and the Antenatal clinic (ANC) surveillance. The cases are reported below in chronological order:
Case 1: During the Acute Febrile Illness (AFI) surveillance between 10 to 16 February 2016, a total of 93 blood samples were collected at BJ Medical College (BJMC), Ahmedabad, Gujarat State. One sample from a 64-year-old male presenting with febrile illness of 8 days’ duration (negative for dengue infection) was found to be positive for Zika virus at BJMC, Ahmedabad. This is the first Zika positive case reported through AFI surveillance at BJMC, Ahmedabad, Gujarat State.
Case 2: A 34-year-old female, delivered a clinically well baby at BJMC in Ahmedabad on 9 November 2016. During her hospital stay, she developed a low grade fever after delivery. No history of fever during pregnancy and no history of travel for the past three months was reported. A sample from the patient was referred to the Viral Research & Diagnostic Laboratory (VRDL) at the BJMC for dengue testing and thereafter found to be positive for Zika virus. She was discharged after one week (on 16 November 2016). The sample was re-confirmed as Zika virus positive by RT-PCR and sequencing at NIV, Pune.
Case 3: During the Antenatal clinic (ANC) surveillance between 6 and 12 January 2017, a total of 111 blood samples were collected at BJMC. One sample from a 22-year-old pregnant female in her 37th week of pregnancy has been tested positive.
WHO risk assessment
This report is important as it describes the first cases of Zika virus infections and provides evidence on the circulation of the virus in India. These findings suggest low level transmission of Zika virus and new cases may occur in the future. Efforts to strengthen surveillance should be maintained in order to better characterize the intensity of the viral circulation and geographical spread, and monitor Zika virus related complications. Zika virus is known to be circulating in South East Asia Region and these findings do not change the global risk assessment. WHO encourages Member states to report similar findings to better understand the global epidemiology of Zika virus.
The risk of further spread of Zika virus to areas where the competent vectors, the Aedes mosquitoes, are present is significant given the wide geographical distribution of these mosquitoes in various regions of the world. WHO continues to monitor the epidemiological situation and conduct risk assessment based on the latest available information.
Prevention and control relies on reducing mosquitoes through source reduction (removal and modification of breeding sites) and reducing contact between mosquitoes and people. During outbreaks, health authorities may advise that spraying of insecticides be carried out. Insecticides recommended by the WHO Pesticide Evaluation Scheme may also be used as larvicides to treat relatively large water containers.
Basic precautions for protection from mosquito bites should be taken by people traveling to high risk areas, especially pregnant women. These include use of repellents, wearing light colored, long sleeved shirts and pants and ensuring rooms are fitted with screens to prevent mosquitoes from entering.
WHO does not recommend any travel or trade restriction to India based on the current information available.