Chan said: �The level of alarm is extremely high. Arrival of the viras been associated with a steep increase in the birth of babies with abnormally small heads.�
Chan outlined four reasons for alarm: �First, the possible association of infection with birth malformations and neurological syndromes. Second, the potential for further international spread given the wide geographical distribution of the mosquito vector. Third, the lack of population immunity in newly affected areas. Fourth, the absence of vaccines.�
This year�s el Ni�o weather patterns mea