This past week, a woman who recently returned from a trip to Haiti became Ohio’s first victim of the Zika virus, and soon thereafter a man coming back from Haiti to Stark County, Ohio, became its second.
Taking the public spotlight just a year after the Ebola crisis, the Zika virus is now causing considerable concern around the world. The virus is associated with rashes, soreness, joint pain and fever, and pregnant women with the virus have given birth to a higher number of babies with underdeveloped brains.
However, the impact that the virus is likely to have in Cleveland may be less than some residents fear, said Ronald Blanton, professor of International Health and Epidemiology & Biostatistics at the Case Biomedical Research Building, and Daniel Tisch, associate professor of epidemiology & biostatistics. Blanton and Tisch are two researchers who study viruses here on campus.
The Zika virus was first discovered in (and named for) the Zika forest in Uganda during the 1940s, and was initially thought to only infect monkeys. Although this belief was quickly refuted when isolated cases of human infection turned up occasionally over the decades, it was not until very recently that the virus was considered a threat.
“Frankly, nobody saw any disease with [the virus] until about 2007, when it seemed to have migrated to Asia,” said Blanton. “Particularly, there were large outbreaks in Yap and the Easter Islands. But even so, it was still considered a relatively mild infection.”
All of that changed a few years later, during the spring of 2015, when an aggressive outbreak of the Zika virus occurred in South America.
According to Blanton, in Brazil, where the virus first turned up in the most recent outbreak, those afflicted displayed some of the most notable symptoms known from previous instances of the disease, especially fever, joint pain and a rash that, in his words, “was remarkable, almost a total body rash.”
“An American investigator [in Bahia, Brazil] … within minutes … turned completely red,” said Blanton. “If you didn’t know it was an infectious disease, you would have said that this person was having an allergic reaction.”
“[The microcephaly associated with the virus] is very severe,” said Tisch. “In fact, traditionally Brazil had about 150 cases of microcephaly [from various causes] per year. Since the Zika breakout last year, it had 3,500 between October and January.”
Although the infection is spreading rapidly, the vast majority of infected individuals have no symptoms and aren’t as likely to seek treatment, meaning that there is a heightened risk of spreading Zika to pregnant mothers.
“The main symptom [of Zika] is actually nothing,” said Tisch. “Only 10 to 20 percent of people actually display observable disease symptoms.”
According to both researchers, such a lack of outward manifestations of illness is actually quite common among flaviviruses, the genus of viruses to which Zika belongs and which includes more familiar names such as West Nile virus and dengue.
Zika virus is transmitted primarily through mosquito bites and perhaps through sexual activity among infected humans, although it is likely that other bodily fluids—such as blood and saliva—can also serve as media for the transmission of the virus.
One particularly striking aspect of Zika is how rapidly our understanding of it has changed. Only broad generalizations can be made about it, from the structure and characteristics of the virus. Otherwise, scientists only know the basic symptoms it causes.
“We know that Zika, like most flaviviruses, is a self-limited disease,” shared Blanton. “At some point, it will probably burn itself out, especially as the number of people who have been infected grows.”
Furthermore, Blanton feels that viruses in the same family, such as dengue, provide some crucial insights.
“We know that [Zika] gives you sterile immunity,” Blanton said. “Once you have it, it’s gone.”
Scientists also know its genetic structure, which is essential in efforts to develop a cure. There is currently no cure and no vaccine for the virus, but Blanton urges anyone who has contracted it to go to a doctor immediately—both for immediate public health concerns and because the symptoms could actually be the result of some other illness.
At present the main factors in guarding against Zika virus are no different than for any other virus transmitted by mosquitos.
“The risk is much higher in Latin America and the Caribbean,” said Tisch. “People without screens, air conditioning [and] well-built houses… are more prone to contracting the virus. Basically development seems to be a good defense.”
That leads to the question on many local residents’ minds: does Cleveland have anything to worry about?
“I say ‘no,’ with an asterisk,” responded Dr. Blanton.
For now, winter makes local spreading of the virus by mosquitoes unlikely, and the most common insect vector, the mosquito Aedes aegypti, does not live in this area. However during the summer Cleveland does have a less common vector, Aedes albopictus, also known as the Asian Tiger Mosquito, and travellers between Cleveland and other locations could transmit the virus.
The bottom line?
“I don’t think there’s too much reason to worry right now, although we might have to be a bit more careful in the summertime,” said Tisch.
As understanding of this virus rapidly advances, the Centers for Disease Control and Prevention (CDC) have released sets of guidelines to prevent the spread of this disease both through sexual activity and through mosquito bites in warmer climates. These can be found on the CDC website.