Pregnancy problems not necessarily tied to Zika viral load or Dengue fever
Congenital Zika virus syndrome -- a pattern of birth defects found among fetuses and babies infected with the virus -- is a newly identified condition that occurs when women are infected during pregnancy. It is unknown to what degree the amount of Zika virus in the mother, the extent of Zika symptoms or the presence of prior dengue antibodies contribute to the syndrome. Laboratory studies suggest there is a phenomenon called antibody dependent enhancement, in which the presence of pre-existing dengue antibodies would enhance Zika's virulence, increasing risk to the fetus. Clinical studies, however, have found no evidence of this. It has also been unclear whether a high viral load, or the presence of Zika symptoms, would be associated with risk of harm to the fetus, or if there is a direct relationship between the amount of virus in the blood and severity of symptoms in the mother. Researchers developed an assessment tool to gauge severity of symptoms based on duration of fever,...