The University of Arizona and the Zika Virus | Aug 24, 2016

An important facet of working in the field of public health is responding to infectious diseases that threaten communities. While there are a number of infectious agents in the U.S. that meet that criteria, the one that is currently foremost in the mind of the public is the Zika virus, a pathogen spread by mosquitoes that has reached pandemic levels.

As Zika becomes an increasing concern at home and abroad, the U.S. government and public health professionals alike are increasingly taking measures to protect and educate the population against the growing threat. As a part of these efforts, researchers at the University of Arizona are playing an important role in responding to Zika.

The current state of the Zika virus

The Zika virus is spread primarily by the Aedes genus of mosquitoes (Ae. aegypti and Ae. albopictus) which become infected during feeding and can then transmit the virus to another individual eight to 12 days later. The virus can also be spread through sexual contact. Though the Centers for Disease Control and Prevention reported the Zika virus was originally discovered in 1947, there had only been small localized transmission before 2007, when the first large outbreak was reported on the Island of Yap. This was followed by a 2013/2014 outbreak in French Polynesia and in 2015, large numbers of cases were identified in Brazil. Zika virus has since spread to the vast majority of countries in South America and Central America.

According to the CDC, there were 1,962 known cases of the Zika virus in the continental U.S. and the District of Columbia as of August 10, 2016. Six cases were locally transmitted in Miami-Dade County, FL. While no local transmission has been confirmed in other areas of the U.S. the Aedes mosquitoes inhabit much of the southern continental U.S. and extend north into the eastern seaboard. The vast majority of the cases of Zika identified in the U.S. are the result of people infected with the virus while traveling in a country with the virus, though 22 cases are linked to sexual transmission.

For the most part, symptoms of Zika are mild, and may include rash, fever, joint pain, red eyes, headache and muscle pain. The World Health Organization reported that these symptoms usually only last two to seven days. Up to three-quarters of those infected experience no symptoms at all. While those infected with the virus rarely die or are hospitalized, it poses a significant health risk during pregnancy. Zika is associated with a condition called microcephaly, a birth defect which is characterized by a smaller than average head size and incomplete brain development in the infant.

Though little is known about the condition, it appears that it can develop in a fetus when the pregnant mother is infected with the virus. Not all women who become infected during pregnancy will go on to have a baby with microcephaly and the greatest risk is when infection occurs during the first trimester. Other neurological conditions are also linked to Zika infection including Guillain Barre. The range of more minor neurological problems that may be faced by babies born to women infected with Zika virus are not yet known.

The role of the University of Arizona

Researchers at the University of Arizona are currently playing an important role in addressing the Zika virus in the U.S. Multiple teams across several departments are working on projects related to the virus. One such researcher is Kacey Ernst, Ph.D., M.P.H., an associate professor in the Department of Epidemiology and Biostatistics in the Mel and Enid Zuckerman College of Public Health

Ernst and her colleagues have worked with other viruses transmitted by Aedes mosquitoes, namely dengue in the past. When Zika became a growing concern, it made sense to expand their focus to include the virus.

“The team I work with at the U of A and the National Center for Atmospheric Research has an R01 from the National Institute of Health and we were originally looking at the emergence of dengue virus in the Arizona-Sonora border region,” Ernst said. “Then Zika emerged, and because the same vector transmits dengue that transmits Zika, the work transfers well. This put us in a good position to do some of this work.”

One of the projects the team undertook was mapping regions of the U.S. that are at high risk for outbreaks of Zika. It is based on four main determinants:

  • The projected density and seasonality of Ae. aegypti mosquitoes – the primary vector for Zika virus.
  • Travel to areas where Zika is being transmitted
  • History of other Aedes borne viruses
  • Indicators of poverty

The local transmission in Miami-Dade matches with the predicted area of highest risk generated by the team, led by Dr. Andrew Monaghan a climatologist at the National Center for Atmospheric Research. The kind of map that is created is called a geographic information system (GIS), and can be designed to gather, store, analyze and present geographic or spatial data.

“GIS is something that over the past couple of decades has really blossomed into an incredibly important tool for people in public health,” Ernst said. “When I was a graduate student it was just starting to become popular. But now I think people are starting to recognize how important recognizing the spatial patterns of diseases is. And increases in personal computing power makes it much simpler as well.”

Mapping of other health conditions, such as cancer and heart disease can also prove useful. It can
even be used for preventive measures, such as to see where people are getting vaccines and where they are not.

In line with the work that is being done at the University of Arizona, Ernst gave testimony before the U.S. House of Representatives Committee on Science, Space and Technology, Subcommittee on Research and Technology on May 25 regarding the state of the Zika virus in the U.S. Her presentation included information on the transmission of the virus by the Aedes mosquito, the areas that these insects are found in, current knowledge gaps about the spread of the virus and the need for additional field data to confirm existing predictions about Zika. Ernst reported that investing in the collection of epidemiological and entomological data would not only help public health officials respond to Zika, but to the threat of future mosquito borne illnesses as well.

The future of Zika in the U.S.

As Zika continues to spread, the disease is becoming an increasing priority of the U.S. government. In a statement on Zika released by the White House on July 1, President Obama emphasized the need for Congress to take action and provide the necessary funds to combat the virus before it spreads to the continental U.S.

“… the most important thing that we can do right now is to actually reduce the incidents of Zika,” Obama stated. “We can issue precautions for travel to areas that have Zika. We can give people guidelines in terms of how to deal with it if they get infected. But this is actually something that we could reduce the risks if Congress does the right thing and allocates the dollars that are needed right now to get the job done.”

In addition to the education measures and community actions that the president recommended as preventive measures, he emphasized the importance of developing a vaccine to protect against the virus. Ernst agreed that it is an important step.

“A vaccine is probably the best solution, because Zika is insidious in that it doesn’t present,” Ernst said. “Most people don’t show symptoms. Children can be born with microcephaly and the mother didn’t even know she was sick. .. If we can get a good vaccine that provides robust immunity that would be an amazing accomplishment.”