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Green Risks: March 2020

As of February 24, 2016 the Center for Disease Control and Prevention reports that there have been 107 cases of Zika within the United States, all of them were travel associated (including the one that was sexually transmitted). In addition, in the U.S. Territories of Puerto Rico, American Samoa and the US Virgin Islands there have been 39 cases of locally acquired Zika virus and 1 case of travel associated Zika Virus.

The disease symptoms which include fever, rash, joint pain, myalgia, headache, pain behind the eyes and conjunctivitis (pink eye) are usually mild and last for 2 to 7 days. Infection may go unrecognized or are misdiagnosed as dengue, chikungunya or other viral infections that cause fever and rash. Many do not even know they have Zika, according to the CDC only 20% of people infected with Zika virus will develop symptoms.

The concern of course is the possible association of Zika Virus with a serious birth defect, microcephaly, babies born with abnormally underdeveloped heads, and other poor pregnancy outcomes in babies of mothers who were infected with Zika virus while pregnant. In addition to an observed connection to other neurological disorders. Several months after the introduction of the Zika virus into Brazil, there was an increase in the occurrence of congenital microcephaly by twenty times.Two recent studies have strengthened this connection. The first study was a tissue and cell bench study that showed that the Zika virus selectively damaged the cells necessary to develop the brain’s cortex, killing the cells and preventing the development of new brain cells .Read the study here.

Published in the New England Journal of Medicine, the second study looked at the 88 women at one medical clinic in Brazil.The clinic tested pregnant women who came to the clinic with fever and a rash a for the Zika virus. Of the women who tested positive for the Zika virus and had additional followup (several of the women declined further testing), 29% suffered a series of negative outcomes including fetal death, tiny heads, shrunken placentas and nerve damage including blindness. Besides the high percentage of babies effected, it also did not matter which trimester of pregnancy the mother was in when she became infected with the Zika virus. A much larger study involving 5,000 women is due out by summer.

The CDC is working with international partners to study infants with microcephaly to identify what role various factors, including Zika virus, may play in this birth defect and is closing in on Zika Virus as a factor of the birth defect. Since November 2015, CDC has been developing methods for testing for the Zika in tissue samples. In December 2015, tissues samples from two newborns (born at 36 and 38 weeks gestation) with microcephaly who died within 20 hours of birth and two miscarriages (at 11 and 13 weeks) were submitted to CDC, from Brazil, for testing for suspected Zika virus infection.

All four mothers had clinical signs of Zika virus infection, including fever and rash, during the first trimester of pregnancy, but did not have clinical signs of active infection at the time of delivery or miscarriage.. Samples included brain and other autopsy tissues from the two newborns, a placenta from one of the newborns, and products of conception from the two miscarriages. The studies showed the presence of Zika virus in the brains of infants born with microcephaly and in placental tissues from early miscarriages. This testing has been the best evidence to date of the connection of the Zika virus to microcephaly.

Several media reports in last month suggested that a pesticide called pyriproxyfen might be linked with microcephaly. These media reports appear to be based on a February 3, 2016 publication authored by an Argentine physicians organization, which claims that the use of pyriproxyfen in drinking water in Brazil is responsible for the country’s increase in microcephaly cases. Pyriproxyfen is a larvacide widely used to control the spread of disease causing mosquitos.

The World Health Organization has approved the use of pyriproxyfen for the control of disease-carrying mosquitos. Pyriproxyfen is a registered pesticide in Brazil and other countries, it has been used for decades, and it has not been linked with microcephaly. In addition, exposure to pyriproxyfen would not explain recent study results showing the presence of Zika virus in the brains of infants born with microcephaly. The CDC is dismissing the reports of pyriproxyfen association with the frightening increasing in microcephaly cases as non-causal.

Microcephaly can happen for many reasons, including genetics, maternal infections, and being close to or touching toxins during pregnancy. Results of recent epidemiologic and laboratory studies discussed above performed in Brazil and the United States strongly support, but don’t yet prove, the link between Zika virus infection during pregnancy and microcephaly. Nonetheless, we need to worry about the spread of the Zika virus to the United States.

The Zika Virus will spread in the United Stated to people who have not traveled by a mosquito drawing blood from an infected individual incubating the virus and then spreading it to others; also, it is confirmed that the Zika virus can spread through sexual contact.. Infected mosquitoes will travel in cargo and planes will carry the Zika virus north. Infected people will carry the disease north and it will spread through our mosquito populations. Our own Asian Tiger Mosquito, Aedes albopictus, is a cousin to the mosquito carryin the Zika virus in Brazil, South and Central America.

The Asian Tiger mosquito entered the United States in shipments from northern Asia in the mid-1980s. It can survive in a broad range of climates and has spread rapidly from the point of first detection in the south-central United States to the entire eastern and central U.S. and now California. Reanalysis of the mosquitoes captured in a 2007 mosquito study in Africa identified the presence of the Zika virus in the Asian Tiger mosquito. Thus, this insect, known to be the vector of dengue and chikungunya, also can carry the Zika virus. The good news for us is so far the winter die off in the more northern states has limited the populations of the mosquito and the diseases that the Asian Tiger mosquito can spread. We need to begin preparations for the summer mosquito season.