UNITED NATIONS, Feb. 23 (Xinhua) — The World Health Organization (WHO) chief, Margaret Chan, is in Brazil to assess the Zika virus situation and response, a UN spokesman said here Tuesday.

Chan is visiting Brazil together with the director of the Pan American Health Organization, Carissa Etienne, Dujarric said at a daily news briefing here.

Their itinerary includes meetings with Brazilian President Dilma Rousseff on Tuesday and a visit to the National Center for Risk and Disaster Management, Dujarric said.

The visit comes after an increase in babies born with microcephaly in northeast Brazil.

The WHO still cautions that more investigation is needed to better understand the relationship between microcephaly in babies and the Zika virus outbreak.

The WHO said that an increase in Guillain-Barre syndrome in Brazil has coincided with Zika virus infections.

The Zika outbreak in Brazil has caught the attention of the WHO as the virus would cause infants to be born with microcephaly if their mothers are infected during pregnancy.

More than 4,000 reported cases of microcephaly have been registered in Brazil, among them more than 400 have been confirmed. Of the confirmed cases, 141 were attributable to the Zika virus.