A MONTH-LONG tour of Brazil in a minibus has led to Oxford University researchers mapping the spread of the Zika virus for the first time.

Scientists from the university's Department of Zoology have been able to shed new light on the disease and its rapid spread through the Americas.

It followed a trip across the country in June last year in a minibus equipped with cutting-edge technology to take DNA samples from people along the way.

Dr Nuno Faria, one of two Oxford researchers who took part in the study, said: "Despite there being probably millions of cases of the Zika virus in Brazil there was only a handful of known virus genomes prior to our work.

"A better understanding of the virus's genetic diversity is critical to vaccine design, and also to identify areas where surveillance is most needed."

In February 2016 Zika, a virus mostly spread by mosquitoes, was declared a 'public health emergency of international concern' by the World Health Organisation (WHO).

It can be transmitted from a pregnant woman to her unborn baby, causing problems including severe microcephaly – a birth defect resulting in a smaller head.

On May 12 this year Brazil declared an end to national emergency status for Zika as the number of cases in the country dropped 95 percent in the first four months of the year compared to the same period a year ago.

The Oxford pair travelled 2,000km across northeast Brazil together with researchers from Birmingham University, testing samples from more than 1,300 infected patients.

By carrying out genome sequencing to understand the virus's genetic make-up the team was able to track the spread of Zika across Brazil.

Professor Oliver Pybus said: "We generated Zika virus genomes to establish the virus’ epidemic history in the Americas.

"We showed that the virus was present in Brazil for a full year prior to the first confirmed cases in May 2015.

"We also found that northeast Brazil, which was the region with the most recorded cases of Zika and microcephaly, was the nexus of the epidemic in Brazil and played a key role in its spread within Brazil to major urban centres, such as Rio de Janeiro and São Paulo, before spreading across the Americas."

During the journey the researchers used a portable DNA sequencer known as MinION, created by university spin-out company Oxford Nanopore Technologies.

The portable device weighs less than 100g and is powered by the USB port of a laptop, making it ideal for cross-country fieldwork.

Professor Nick Loman of Birmingham University's School of Biosciences said: "Genome sequencing has become a powerful tool for studying emerging infectious diseases.

"Real-time sequencing is of vital importance when managing outbreaks as it can provide real insight into how a virus is spreading, transmitting and evolving.

"This new protocol will doubtless prove hugely beneficial to researchers working in remote areas around the world during times of viral outbreaks."