It is worth noting that higher levels of these M2 macrophages are already present in pregnant women in order “to prevent the womb from rejecting the fetus.” The researchers found that the Asian strain creates a surge in M2 macrophage replication, which ultimately results in immune system suppression. Furthermore, they found that pregnant women are most vulnerable to the Asian Zika virus during their first and second trimesters.
“Zika virus infection of merely 4% of the target white blood cells was enough to convert a big population of ‘white knights’ into immune suppressive M2 macrophages. African Zika virus infection increased immune suppression to around 10%. This number skyrocketed to almost 70% for expectant mothers infected by the Asian Zika virus,” according to the press release.
The researchers compared the findings yielded from their experiment with blood samples taken from 30 pregnant women—10 from each trimester—who had been diagnosed with the Asian strain of Zika virus. Furthermore, they assessed blood samples taken from 15 uninfected pregnant women—about five from each trimester.
They found that expression of the genes ADAMTS9 and FN1—known to be associated with pregnancy complications—was “abnormally high” in the samples taken from the 30 pregnant women diagnosed with Asian Zika virus infection. Increased levels of ADAMTS9 may account for underweight newborns and complicated delivery; womb abnormalities, high maternal blood pressure, and “unusually small babies,” have all been associated with high levels of FN1 in past research.
As mosquito-borne illnesses become more prevalent because of environmental issues such as climate change and global warming, it is important that researchers continue to make developments that work to increase understanding regarding who is most susceptible to these infections. The more that is known, the better researchers and health officials can work to protect those who are most vulnerable.
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