India among regions ideal for Zika outbreak

Global tropical and subtropical regions inhabited by over 2.7 billion people—including 2 million sq. km in India—are at high risk of Zika


Photo: Oxford University and the University of Washington/ eLife
Photo: Oxford University and the University of Washington/ eLife

New Delhi: Large parts of India have the ideal environment for a Zika virus outbreak that first erupted in Brazil in 2015, a new study said.

Global tropical and subtropical regions inhabited by over 2.7 billion people—including 2 million sq. km in India—are at high risk of Zika, the study which mapped the global transmission of the deadly virus said.

Scientists at the University of Oxford and the Institute for Health Metrics and Evaluation, Seattle, created the global map which identifies areas across the world with similar environmental and socioeconomic characteristics as areas where the virus has been reported so far. The research that was published in eLife journal, uses parameters including weather-related data such as precipitation, land cover, and also complex temperature-based virus incubation models.

Photo: Oxford University and the University of Washington/ eLife
Photo: Oxford University and the University of Washington/ eLife

“We have comprehensively assembled all the data for Zika occurrence in humans, displayed it as a map, and combined it with detailed predictions of where the virus could spread next,” said lead author Janey Messina from the University of Oxford’s Department of Zoology in a press release. “Our global risk map reveals priority regions where authorities could intervene to control the vector population and where surveillance of the virus should be concentrated in order to improve rapid outbreak response and clinical diagnosis,” added Messina.

The study noted that although no symptomatic cases have yet been reported in India, a large part of the country is at potential risk for Zika virus transmission, that is over 2 million sq. km, with environmental suitability extending from its northwest regions through to Bangladesh and Myanmar. The Indochina region, southeast China, and Indonesia all have large areas of environmental suitability as well, extending into Oceania, the study added, according to the study.

The study further showed that large parts of sub-Saharan Africa are at potential risk, especially in the Democratic Republic of Congo and surrounding areas. The authors expressed surprise at the fact that no large outbreaks have been reported in Africa or Asia despite large portions being highly suitable for transmission. “This could be due to under-reporting, misdiagnosis, or a high level of immunity in the human population, where the virus has been present for a long time. It was first discovered in Uganda in 1947,” noted the authors in a release by University of Oxford.

The virus was first introduced to Brazil in 2013, but was reported only in 2015. Pregnant women with Zika virus are at higher risk of giving birth to infants with microcephaly, in which brain development in inhibited. This correlation was firmly established recently by studies. From 1 January 2007 to 13 April 2016, Zika virus transmission has been recorded in 64 countries and territories out of which 42 countries are experiencing first outbreaks since 2015, with no evidence of transmission before.

“Our findings that a global area inhabited by over 2.7 billion people is highly suitable for transmission of Zika virus, combined with the rapid cross-continent spread we have already seen, emphasise why the World Health Organisation has declared the current outbreak as a Public Health Emergency of International Concern,’ said David Pigott from Seattle’s Institute for Health Metrics and Evaluation, in a release.