The spread of the Zika virus, a mosquito-borne disease, could be associated with the increasing occurrence of brain and skull deformities in newborns in South America. Health authorities in the region are on the alert as cases of microcephaly are under investigation, The Telegraph reported.

In the state of Pernambuco, Brazil, the average number of microcephaly cases are only 10 per year, but since the beginning of 2015, there are already 141 reported cases. In the state of Rio Grande do Norte, there were 35 confirmed microcephaly cases just from August to Nov. 16. The same trend could be observed in the states of Paraiba and Piaui.

Microcephaly is a condition in which a baby's brain and skull do not develop completely and end up being deformed or abnormally small.

The Pan American Health Organization of the World Health Organization released an Epidemiological Alert on Tuesday telling its member states "to remain alert to the occurrence of similar events in their territories and to notify its occurrence through the channels established under the International Health Regulations (IHR)."

"In order to contribute to further understanding the etiology of this event, PAHO/WHO urges Member States to notify any increase of microcephaly or other neurological disorders in newborns that cannot be explained by known causes," the alert said.

The link between Zika virus and microcephaly has not been established, but scientific institute Fiocruz in Brazil reported that the virus was present in the amniotic fluid of two pregnant women whose babies were detected to have abnormally small heads.

Additionally, in Rio Grande do Norte, 80 percent of women whose babies displayed microcephaly manifested symptoms of Zika virus infection during the first trimester of their pregnancy, according to Dr. Kleber Luz from the Federal University of Rio Grande do Norte, The Telegraph reported.

Cases of Zika virus infection were reported last week in the Yucatan in Mexico, according to NPR. On Thursday, the virus was reported in the Caribbean, where the Ministry of Health urged residents to destroy possible breeding sites of mosquitoes, according to the Jamaica Observer.

The Zika virus is transmitted by the Aedes mosquito. It presents mild symptoms: fever accompanied by rash, conjunctivitis and joint pain. However, scientists have yet to discover the full effects of the infection, NPR reported.