The latest public health panic is over a disease most Americans (even doctors) have never heard of. Zika virus disease (ZVD) is carried by the same mosquito, Aedes aegypti, as other Third World diseases, including dengue and chikungunya.
ZVD is asymptomatic in about 80 percent of infected individuals. In about 20 percent, it causes a mild, self-limited disease with fever, rash, joint pains, and conjunctivitis (red eyes).
Some 4,000 babies in Brazil have reportedly been born with severe birth defects, including microcephaly (small head), and officials suspect ZVD is the cause.
Mild disease, rash, birth defects: reminds one of rubella (German measles). Viruses can cause birth defects.
On Feb 1, the World Health Organization (WHO) declared a Public Health Emergency of International Concern, the same category as Ebola. American health authorities issued a travel advisory for pregnant women planning to visit Brazil or many other countries in Latin America or the Caribbean
A case of apparent sexual transmission in Dallas led to a warning that men who had been exposed to Zika should abstain from sex with a partner who might be pregnant.
Zika is by no means new. It was first identified in humans in 1947 in Uganda’s Zika Forest. What is new, and “scary,” according to CDC director Thomas Frieden, is the association with microcephaly and other fetal harm.
There is, however, still no definitive proof that microcephaly and associated defects are caused by ZVD. Some interesting facts:
- So far the microcephaly cases are all in Brazil, not in the 35 other countries with ZVD, though an earlier cluster was observed in 2014 in French Polynesia.
- As of Feb 3, only 17 of 404 cases of confirmed microcephaly tested positive for Zika.
- Brazil had seen an increase in pertussis in fully vaccinated children, so early in 2015 officials mandated immunizing all pregnant women with DTaP (diphtheria/tetanus/acellular pertussis) vaccine, without awaiting proof of efficacy or safety in the developing baby. Only 32 pregnant women were enrolled in a trial of this vaccine, and no results are posted yet.
- A variable number of months after the vaccinations, the number of microcephaly cases increased from essentially zero in October 2015 to 1,200 in November, and continued to climb.
- Because of a measles outbreak, there was a major vaccination campaign with MMR (measles/mumps/rubella) in Pernambuco, Brazil, in late 2014. This is a live virus vaccine, and many women likely received it in early pregnancy or shortly before becoming pregnant. Congenital rubella syndrome can cause microcephaly among many other problems, but this was not found in surveillance of American women who inadvertently received MMR around the time of conception.
The complex symphony of human development can be thrown off by many things—even a little alcohol. Some birth defects might be related to ZVD. But all environmental exposures need to be scrutinized, including drugs, agricultural chemicals, contaminated water, and vaccines. Remember thalidomide?
The unfortunate babies are being used to promote political causes: legalization of abortion in Latin America, or the fight against “climate change.”
With warmer temperatures, mosquitoes might be able to move further north, it is claimed. But Aedes aegypti arrived in North America around 1980 in a shipment of used tires, not waiting for a temperature increase. And mosquito-transmitted malaria was prevalent in Minnesota during the Little Ice Age. Climate change or not, mosquitoes will not be inconvenienced if we bankrupt our coal industry or ban SUVs.
Travel restrictions would greatly harm the economy of Latin American countries, especially as Brazil is preparing to host the Olympics. Of course there is no screening at all of illegal entrants to the U.S. The key public health measure is mosquito control. Mosquito-borne diseases, after a time when it was thought that even malaria might be wiped out, began increasing worldwide when the U.S. banned the most effective public health weapon of all time: DDT. If Zika causes rethinking of this disastrous decision, even though other deadly threats like malaria have not, it will save millions of lives—and even help us win the war on bed bugs.
The damaged babies are a terrible tragedy. How can we prevent more? Instead of waiting for some future vaccine against a virus that may prove innocent, we could stop transmission now with effective mosquito control in affected areas. We could also immediately stop deliberately exposing women who might be pregnant to medicines or vaccines without thorough safety testing.