Georgia got its first travel-related case of the Zika virus in January and concern spread across the state.
After blanketing Brazil, causing devastating birth defects across that nation, the disease migrated through South and Central America as well as the Caribbean. It's rapid spread was fueled in large part by mosquitoes, but also by way of travelers and sexual transmission.
Georgia and other southern states braced for what many feared would be an outbreak here. If that happened, a subsequent rash of newborns affected by Zika-related syndromes such as microcephaly seemed probable.
But now that temperatures have dropped and mosquito season has ended across much of the state, it’s worth noting that Georgia did not see a Zika outbreak. So were the Zika warnings much ado about nothing, at least in Georgia?
Public health officials say, absolutely not. They argue the Zika threat will be around for several more years at least and caution that several pregnant women in the state are infected with the virus, meaning they could give birth to babies with health problems.
Last week, the World Health Organization announced it no longer considered Zika a global health emergency but said it remains a chronic threat.
“We are not downgrading the importance of Zika. By placing this as a long-term program of work, we are saying Zika is here to stay,” said Dr. David Heymann, the chairman of the emergency committee on Zika virus and microcephaly.
Sounding the Alarm
So far, at least, Georgia has escaped the fate of Florida, which has been the epicenter of the virus in the continental United States.
Mosquitoes in pockets of the Miami-Dade area were found to be transmitting the disease in late June. By mid-November, Florida experienced 139 locally- acquired cases, most of them clustered in Miami. The spread created panic among pregnant women there and a rush to get tested.
Georgia has only seen 104 travel-related cases of Zika since the first case was reported. So far, not one infection has been caused by in-state mosquitoes.
While many people weren’t concerned about contracting the disease, health officials sounded the alarm throughout mosquito season. An outbreak could be just one bite away, they warned. And because most people who get Zika don’t show symptoms, it could begin spreading with little notice. They implored everyone, but especially pregnant women, to wear bug spray at all times outside. They told people to tip and toss standing water around there homes. They recommended people wear light-colored clothes and long sleeves to avoid being bitten. So why didn’t Georgia have an outbreak and are we in the clear?
State health officials say the warnings weren’t for naught. Though mosquito season may be over now, by the best estimates of both the Centers for Disease Control and the National Institutes of Health, Zika will be around for the next couple of years. In some ways 2016 was a dry run for what Georgia could face in 2017 if the virus spreads by local mosquitoes as it has in Miami. The awareness campaigns are lessons that will carry over should that happen, officials said.
“This particular mosquito season, even though we’ve seen low numbers of mosquitoes that can carry the virus, it doesn’t mean that next season will be the same,” said Chris Kumnick, interim director of environmental health for the Georgia Department of Public Health. “It doesn’t diminish the risk of managing that hazard.”
At-risk pregnancies
As of Nov. 9, the National Health and Human Services Department reported 4,175 cases of Zika in the United States. Of those cases, 1,057 of them were pregnant women. All of that feels very abstract, until you consider that three of those pregnant women are in Georgia. Patient privacy rules prevent the state public health department from saying where those women live, but they are still pregnant, said Dr. Cherie Drenzek, state epidemiologist.
Those women could potentially give birth to babies with some of the same health issues that have plagued babies in Brazil who were exposed to Zika in the womb. The health department, working with the women’s doctors, have been monitoring the women’s pregnancies, getting updates every trimester on fetal development.
Georgia got a CDC grant of $560,000 in August specifically to identify and monitor cases of microcephaly and to monitor the development of babies exposed to Zika while their mothers were pregnant.
Pregnant women are the most vulnerable population to get the virus. Apart from microcephaly, Zika also causes a spectrum of birth defects which researchers have categorized as Congenital Zika Syndrome. In a paper published last month in the Journal of the American Medical Association/Pediatrics, the syndrome includes birth defects that may not be obvious at birth. Where microcephaly causes the brain to under develop and the skull to collapse around the too small brain, Zika can cause four other specific and equally damaging defects including calcium deposits on the brain, limited joint movement, excessive and restrictive muscle tone and scarring in the eye.
But because of the virus’ pernicious nature, some defects may not show up during regular ultrasounds. CDC and NIH researchers say there is a range of defects that may not manifest for months or years after a baby’s birth.
Mosquito wars
Why hasn’t Georgia seen an outbreak like the one in Florida? Two factors; a war for dominance between the two types of mosquitoes that carry the virus and an intense, state-wide drought.
By late spring, the state health department had relaunched its Tip ‘n Toss campaign, a mosquito control effort aimed at homeowners and businesses. People were told to remove all standing water from their bird baths, truck beds, patio furniture and any other outside containers bigger than a bottle cap. A teaspoon of water is enough for mosquitoes to successfully lay eggs, people were reminded.
But by the end of October, Georgia was well below its annual rainfall totals. Atlanta, Athens, Columbus and Macon all had below 33 inches of rain, anywhere from 12 to 16 inches below their respective 30 year averages. That, coupled with a cooler spring statewide and lower humidity levels in early summer, drove mosquito populations down.
While mosquito control and abatement is up to individual counties and municipalities rather than the state, Georgia monitors the insects’ population with light traps around the state. Epidemiologists extrapolate the potential number of the insects in the area based on the number of mosquitoes caught in the traps.
In particular, epidemiologists were looking for the Aedes aegypti and Aedes albopictus breeds, the primary carriers of the disease. For the last five to seven years, the Aedes aegypti population has been dwindling, said Kumnick. That mosquito is responsible for Miami’s Zika outbreak. It is the most efficient in spreading the virus because it only feeds on humans.
In Georgia, the only place the aegypti was found was in Muscogee County; until late September, only 14 of that type had been found. Along the Georgia coast, where some thought a local outbreak might originate, the last time the aegypti was found in traps was 2012 in Chatham County, Kumnick said.
Even the albopictus variety, which feeds on humans as well as animals, was down in numbers.
Travelers’ alert
What state researchers feared was despite the paucity in number, the mosquitoes would bite someone who’d acquired travel-related Zika, kicking off a local outbreak.
“When talking about risk, you have to consider the travel components no matter what,” said Drenzek.
“We have to be making sure that people who travel to areas with active outbreaks protect themselves when they return.”
The CDC advised travelers to wear insect repellent for three weeks after returning from a Zika hot spot and not to have unprotected sex for six months. Virtually all of Georgia’s Zika cases are travel-related.
As each case was confirmed, the state health department quietly set in motion a monitoring protocol for each person with the disease. In addition to the $560,000 in CDC money for pregnancy monitoring, the state health department is using a portion of an additional $1.74 million in federal Zika money awarded in July to carry out the monitoring. Some of the money was set aside to hire four additional epidemiologists for testing potential cases and evaluating at-risk Zika pregnancies.
Epidemiologists track the health of the infected for months after exposure. They also assess their home environments to look for places mosquitoes might breed. In some cases they have had insecticide sprayed around the home.
Neighbors, however, are not notified, raising the question of whether keeping them in the dark increases their risk of exposure. Kumnick said privacy rules prohibit them from telling neighbors.
“It’s a scaled response,” Kumnick said. “We look based on risk surveillance. Our radius is 150 yards to make sure the positive person doesn’t infect the local mosquito population.”
Kumnick said because not all mosquitoes spread Zika, and so few of the culprit breeds have been found, for now the protocol is appropriate.
This month Georgia requested an additional $800,000 from the $1.1 billion federal Zika bill passed by Congress earlier this fall, said Nancy Nydam, spokeswoman for the state public health department.
That money will go toward preparedness for next year. Though the mosquitoes may be just about gone this season, their eggs are not. Those eggs over winter, wet or dry, and will be ready to hatch as soon as the weather warms next summer.
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