India has sent experts to try to contain an outbreak of the zika virus in the popular tourist destination of Jaipur, capital of the northern state of Rajasthan, with a close watch on pregnant women.

Twenty-two people in the city have tested positive, the health ministry said. There is no vaccine to the virus which can cause severe birth defects in unborn children.

Pregnant women in the area are being monitored by the National Health Mission, a body set up by the government to improve healthcare across the country.

"The situation continues to be monitored regularly," the ministry said in a statement late on Monday.

The Toronto-based International Association for Medical Assistance to Travellers said it was advising pregnant travellers to postpone trips to the area, part of India's tourist "golden triangle" of Delhi, Jaipur and Agra, home to the Taj Mahal.

Hist discovered in 1947, the zika virus reached epidemic proportions in Brazil in 2015, when thousands of babies were bom with microcephaly, a brain defect affecting speech and motorfunction.

It is the third such outbreak in India, with the first in the western city of Ahmedabad in January 2017 and the second in the southern state ofTamil Nadu in July 2017. Both outbreaks were "successfully contained", the government said.

The latest cases - in the middle of the country's festival season where many Indians travel, increasing the risk of transmission - come amid a spike in other mosquito-borne diseases, that kill thousands across India each year, according to the World Health Organisation.