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Zika: A Public Health Manager’s Take on the Virus [ Part 2 of 2 ]

Zika: A Public Health Manager’s Take on the Virus [ Part 2 of 2 ]

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Editor’s note: This is Part II of a series on the Zika virus. After the virus was detected in saliva, I did a ton of research to see if and how that discovery would affect medical professionals, specifically our readers in the dental industry. Luckily, I came across Graham McKeen, someone who is well versed in Zika and other communicable diseases, and he answered all of my questions with excellent, relevant information. 

 

Graham McKeen has always been fascinated by diseases that can be transferred to humans from animals and insects, and he’s taken that interest and made it into a career.

As Indiana University’s public health manager, one of McKeen’s most important roles is to be in-the-know and aware of prominent communicable diseases in order to help the university provide education, training and guidance on how to how to best prepare for, respond to and prevent spreading. As referenced in recent news articles, Summer 2016 Olympics talk and Facebook posts with pictures of small-headed infants, Zika is the next big communicable disease on the rise, and the United States is looking like its next target.

The first thing  to know about Zika, McKeen said, is that not much is known.

“We are at the tip of the iceberg with Zika and have a lot left to learn,” he said. “Prior to 2007, there were only 14 known human cases of the disease since it was first discovered in monkeys in the Zika forest of Uganda in 1947. There was never really a good reason to research the virus until very recently, as it was always thought to be minor-league compared to other mosquito viruses of concern, such as Dengue or Yellow Fever.”

But with the recent blow-up of cases spreading across South and Central America, and the Caribbean, and with the virus knocking on the door of the U.S., health officials are in a race to catch up and learn as much about Zika as possible.

What we do know

Medical officials are getting a pretty good idea of how the virus is presenting itself in humans.

According to McKeen, eighty percent of those infected will be asymptomatic, while the other 20 percent will develop a mild and self-limiting illness consisting of conjunctivitis, fever, rash and joint pain, with less common symptoms including muscle pain and headache. While the exact onset time for the virus is unknown, McKeen said it’s believed to last between a few days and one week.

While they can occur, complications from the virus are very rare. Health officials now believe there is a link between Zika and Guillain-Barré syndrome (GBS), a rare condition of the nervous system in which a person’s own immune system damages the nerve cells, causing muscle weakness and sometimes paralysis.

According to the Center for Disease Control (CDC), the Brazil Ministry of Health has reported an increased number of people who have been infected with Zika also have GBS. GBS is very likely triggered by Zika in a small portion of infections, much as it is after a variety of other infections, and the CDC is investigating the link between Zika and GBS.

“It is not known how common or uncommon GBS is with Zika infections but is believed to be quite rare,” he said. “And while rare, we need to learn and understand more about complications such as Guillain-Barré and their occurrence.”

The first Zika-related death in a U.S. territory was reported in April in Puerto Rico. The CDC reported that the man in his 70s died from internal bleeding caused by  immune thrombocytopenic purpura, a condition similar to Guillain-Barré that attacked the man’s blood platelets rather than attacking his nerves. According to Tyler Sharp, a CDC epidemiologist working in Puerto Rico, the San Juan man showed the normal symptoms of rash and fever earlier in the year, but they went away. Shortly after, Sharp said, he began having bleeding manifestations and died in hospital care. Three others have died in Brazil since the onset of the spread of Zika, but their cases were unrelated to GBS.

Even with four deaths reported, the most significant effect associated with Zika is the one it has on embryos.

“The biggest concerns we have are with the potential birth defects that can occur from Zika infection, mainly microcephaly, which is a condition in which the baby is born with a smaller than expected head which can mean that they have smaller brains and brain function, and developmental issues,” McKeen said. “There is also the potential for other neurological disorders, as it’s believed the virus can attack neural cells.”

Susceptibility and pregnancy

Because the virus has never circulated to the United States, the entire country is susceptible to contracting Zika.

Unlike most pathogens, McKeen said, no specific population is more susceptible than another, however, he said, the elderly, pre-school-aged children and the immunocompromised are the most likely candidates for any kind of infectious agent. And while the virus could cause temporary illness in its hosts, the affect on expecting mothers is the most severe.

“The populations that we are concerned about the most, of course, are pregnant women and those trying to become pregnant because of the serious complications and risks of birth defects,” he said. “I’d stress that unless you are pregnant, or unless you and your partner are trying to become pregnant, the virus shouldn’t be of great concern for the overwhelming majority of us.”

As of May 20, the CDC changed its diagnostic guidelines to include pregnant women who either tested positive for the virus or showed symptoms. After changing the guidelines, the CDC determined that 157 pregnant women in the 50 United States have the virus, as well as 122 pregnant women in U.S. Territories.

McKeen said pregnant women should avoid travel to Zika affected areas, and male partners of pregnant women who have traveled to areas with a Zika presence should abstain or use condoms for sex until the baby is born.

“Women with Zika virus disease should wait at least eight weeks after symptom onset before attempting conception,” he said. “Men with Zika virus disease should wait at least six months after symptom onset before attempting conception.”

But because 80 percent of those affected are asymptomatic, women and men with possible Zika virus exposure should wait at least eight weeks after the last date of exposure before attempting conception.

Transmission

Officials have confirmed the virus can be transmitted by mosquito bite, cross-placenta, via blood transfusions and from sex with an infected man, as the virus lasts a lot longer in semen than in blood. While there have been a few cases of person-to-person transmission via sex within the U.S., there has yet to be any local transmission from mosquito bites.

Local transmission in the U.S. would look like this:

  1.  A person travels to the U.S. with the Zika virus actively circulating in his or her blood.
  2. A female mosquito that uses blood in order to reproduce bites the infected person.
  3. The female mosquito harbors the virus and then bites and infects a new person.

“It would take a few cycles of this to for an outbreak to be established,” McKeen said. “All cases in the US thus far have been imported or travel-associated cases.”

As of May 18, the CDC reported a total of 544 travel-associated cases in the U.S.: 10 were sexually transmitted and one case was found in a person with Guillain-Barré syndrome. The number of travel-associated cases within the United States has grown by more than 100 in less than a month, as the count was 426 at the end of April. The CDC also reported a total of 832 cases of locally transmitted cases in U.S. territories. Five of those affected have Guillain-Barré syndrome.

The specific mosquito carrier, Aedes aegypti, is what McKeen referred to as the “quintessential asshole of the mosquito world.”

“They like urban areas, trash, humans and are not picky biters like some other mosquitos,” he said. “They are also aggressive daytime biters and are sip-feeders, in that they like to bite a lot of different people for sips of their blood and therefore are really good at spreading diseases like Zika.”

While other Aedes species of mosquitoes are capable of spreading Zika, the Aedes aegypti, also known as the Asian tiger mosquito, have the widest range and at this point are believed to have the largest potential to create widespread or explosive transmission of the virus in the U.S., McKeen said.

Southern states–New Mexico, Arizona, Florida, Alabama, Mississippi, Louisiana, Texas and potentially Southern California–could see the first cases of local transmission, as they are all areas in the US that have the largest populations of the Aedes aegypti mosquito.

“While it’s hard to predict these things, I think it’s safe to assume that there could be some local transmission of Zika in the U.S. sometime this summer,” he said. “However, I do not believe that it will be anywhere near the same scale as the outbreak in some of these South American and Caribbean countries. We have better vector control programs and better housing conditions in the US compared to the currently affected areas.”

Even with the potential of local transmission in the U.S. looming, a massive, country-wide outbreak is not exactly imminent.

“When the Caribbean experienced a recent outbreak of Chikungunya–another mosquito-borne virus that began there in late 2013–we had the same concerns of an outbreak in the U.S.,” McKeen said, adding that both Chikyngunya and Zika are spread by the same mosquito. “We did end up having local transmission, but it was limited to just 12 reported cases in Florida, while the Caribbean, Central, and South American countries have experienced an estimated 1.7 million cases since late 2013.”

Medical professionals and the Zika virus 

McKeen said he doesn’t think the risk to medical professionals is of any greater concern than any other biological hazard or blood-borne pathogen they might come in contact with on a daily basis. He also noted the strict Standard and Occupational and Safety Health Administration bloodborne pathogen trainings in place, and he said those would be sufficient when protecting against any virus, including Zika.

“Any bodily fluid from patients should be handled with care and caution for potential exposure to any pathogens,” he said. “I don’t think that any extra precautions would be necessary as long as standard protocols and procedures are followed. While it’s not known, Zika is not believed to be transmitted via saliva at this time.”

McKeen suggested to avoid any blood-to-blood contact with anyone who has an active Zika infection, as the virus typically circulates in the blood for about one week after infection.

Where we go from here

There is no specific treatment or vaccine for Zika—yet.

“It wasn’t until just recently that researchers at Purdue University mapped the structure of the virus which should help expedite the potential for vaccine development,” McKeen said. “There are currently 18 agencies and companies globally that are actively working on vaccine development.”

McKeen said there are trials for vaccines that could begin as early as this year, but it will take until at least next year–and potentially a lot longer–to know if a vaccine works.

“The National Institutes of Health is working on the development of a vaccine that uses DNA of the virus in hopes of allowing the inoculated to develop an immune response,” he said.” However, an attenuated live virus vaccine will most likely end up being the most effective.”

On May 17, the United States Senate The Senate voted  to advance $1.1 billion in emergency financing to combat Zika. The funds will be spent on researching the virus and Zika-related birth defects, sending response teams to limit Zika’s spread and helping other countries fight the virus.

As of now, McKeen said, the best way to prevent infection is to protect yourself from mosquito bites. Use effective insect repellents, wear long sleeves and pants, use air conditioning and use screens to prevent mosquitoes from coming into your home, avoid being outside during dawn and dusk when there is potential for high mosquito activity, and drain and eliminate sources of standing water around the home to prevent mosquito breeding.

“If you do get a mosquito-borne illness, it’s also advised to avoid getting bitten by mosquitos in the week following your illness to reduce the chance of further spread by infecting new mosquitoes,” McKeen said. “It’s also good to self-monitor after travel to areas (that are Zika case-heavy). Be sure to tell your medical provider of your recent travel if that is the case.”

Katie Devereaux
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