Zika Virus: Obscure Pathogen Emerges with New Adaptations

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The Museum’s Health Sciences Department is partnering with the University of Colorado Anschutz Medical Campus to publish a monthly series on the Museum blog called “Know Health”. The articles focus on current health topics selected by CU’s medical and graduate students in order to provide both English and Spanish speaking communities with current, accurate information. The posts in the “Know Health” series are edited versions of articles that first appeared in Contrapoder magazine. Thank you to the students at the University of Colorado Anschutz Medical Campus for bringing these stories to life.

 

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(aka Dr. Nicole Garneau, chair and curator, Health Sciences Department)

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Zika Virus: Obscure Pathogen Emerges with New Adaptations    

By: Molly Terhune, Colorado School of Public Health

ZIka

[en Español]

The Zika virus outbreak in Latin America has raised such alarm that the World Health Organization has declared the epidemic an international public health emergency. The Zika virus was first discovered in a rhesus monkey in Uganda in 1947. It was identified in humans in 1964.1 Since then, the pathogen has moved east through Asia, hopscotching across the Pacific, arriving in Brazil in 2015. 80% of infected adults have no symptoms, and symptoms are fairly mild when they do develop. People with Zika usually experience fatigue, fever, and bloodshot eyes.

The Zika virus was mostly unfamiliar until 2015, when Brazilian health officials noticed an increase in babies born with microcephaly, or abnormally small heads. Depending on the severity of the condition, microcephalic children can suffer intellectual deficiency and developmental delays, difficulty with coordination and balance, neurological problems like seizures, and reduced lifespans. Microcephaly is not the only complication related to Zika. Guillain-Barré syndrome was noted in relation to the 2011 outbreak in French Polynesia. Guillain-Barré is a condition that causes the immune system to attack cells in the nervous system, causing paralysis. Other viruses like Zika can activate Guillain-Barré syndrome, so this relationship was not too surprising to researchers.

Zika belongs to a group of viruses that also includes Dengue, Yellow Fever, and West Nile viruses, all of which are transmitted by mosquitos. Zika is not behaving like the other viruses in its group, which typically do not harm fetuses. Instead, Zika has been confirmed to cross the placentas during pregnancy, infect the nervous system of the developing baby and cause microcephaly. The Centers for Disease Control (CDC) have announced that there is enough evidence to conclude that Zika virus infection during pregnancy is a cause of microcephaly and severe fetal brain defects. There is similar evidence that the virus is capable of crossing the tissues of the prostate gland. This means that Zika can most likely be sexually transmitted through semen.

Researchers would like to understand more about transmission and establish more efficient diagnostic testing. In the lab, the best method for diagnosing Zika is the reverse-transcription polymerase chain reaction (RT-PCR), which identifies Zika’s genetic material. This test has already shown evidence of the virus in multiple tissues of a microcephalic infant. A simpler blood test that looks for an antibody to the Zika virus is more widely available, but less reliable because it may yield a false positive result if dengue or another similar virus is present.

Right now, preventive action against mosquito bites are the best line of defense. This includes wearing long sleeves and long pants, using insect repellent, and using window screens when available. “All countries in Latin America are very worried about the implications of Zika infections. There is only limited capacity in countries like Guatemala to control the transmission of Zika. Managing mosquito populations through insecticide spraying and the elimination of breeding sites will perhaps decrease the transmission, but it is extremely difficult to contain this type of epidemic. The lack of access to health care makes it even more difficult to determine how extensively Zika has impacted the population in low-income countries,” says Edwin Asturias, M.D., Associate Professor, Section of Infectious Disease, Department of Pediatrics, University of Colorado School of Medicine, and Director of Latin American Projects, Center for Global Health.  

 

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