While the travel-hungry anticipate warmer temperatures and monitor flights for that upcoming summer escape to Caribbean isles or Latin-American landscapes, Los Angeles epidemiologists are doing the same—for a very different reason.
As mosquito season ramps up and California prepares for an influx of the disease-spreading pests, experts gathered Thursday in the Aresty Conference Center at USC's Health Sciences Campus for the Zika Virus Awareness Symposium to discuss the virus' spread, its effects, and ways to control the population of the Zika-spreading Aedes aegypti mosquito.
Aedes isn't the only thing responsible for the seemingly rapid spread of the virus officially linked to causing a slew of neurological development issues in fetuses whose mothers were infected with the virus during pregnancy or shortly before conception.
"A warmer world is a sicker world," said Kelly Middleton, director of community affairs at the Greater Los Angeles County Vector Control District. "And prevention is key."
As the climate continues to warm, mosquitos gain larger areas of the perfect breeding grounds—warm regions with a bit of moisture for laying eggs. As the mosquito population increases, so do the numbers of bites, maximizing potential for Zika and similar viruses like Chikagunya, Dengue and Yellow Fever to spread.
Earth's rising temperatures, however, don't appear to be lowering any time soon, and the Aedes has already been found in several California cities. No cases of mosquito-transmitted Zika have been reported in the state; the first case of sexually transmitted Zika virus was reported in March. A woman was infected by her husband who had recently returned to California from a country where Zika was circulating.
With 500,000 flights arriving in Los Angeles from Zika-infected destinations each month, travel is yet another factor contributing to the potential for spread, said Jae Jung, director of the USC Institute of Emerging Pathogens.
"Globalization is the primary factor causing profound, unpredictable impacts on infectious diseases," said Jung, also chair of the Department of Molecular Microbiology and Immunology at Keck Medicine of USC.
Genhong Cheng, professor of microbiology, immunology and molecular genetics at UCLA David Geffen School of Medicine has tracked what is essentially Zika's genealogy through its mosquito hosts. In a map shown at the symposium, the virus' distribution throughout its history, the image is reminiscent of flight paths.
A similar map created by Annenberg Media using Cheng's data starts with a single Asian mosquito infected with Zika caught in 1966 and goes all the way to the current French Polynesian strain that broke off into 11 subgroups, sickening people in 49 countries.
In a study of two groups of workers going from China to Venezuela, members of the first group returned to China in mid-February infected with one strain, and members in the second group returned two weeks later infected with another strain. Cheng and his team are researching whether a rapid mutation is to blame.
Jung cited Cheng's research, noting that a single emerging pathogen like Zika "can be not just a threat [that can infect thousands], but an opportunity to the fields of science, education, law and business."
Last week, California passed a law mandating that health providers report anyone suspected of being infected with Zika to the local health department to follow up and conduct testing. The state then conducts a review, and reports necessary data to the Centers for Disease Control.
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In addition, CDC established the US Zika Pregnancy Registry and is collaborating with state, tribal, local, and territorial health departments to collect information about pregnancy and infant outcomes following laboratory evidence of Zika virus infection during pregnancy.
Of the 2,400 cases the state has so far tested, more than 90 percent have been women, with 84 percent of them not showing any symptoms of the virus. In April, 1,500 were tested, 34 of which were confirmed cases. Less than 1 percent of those who showed no symptoms tested positive for the virus, while 15 percent who showed symptoms such as a fever, rash, joint pain, or red eyes, tested positive for Zika.
Though Jung may also have called Los Angeles the "gateway of germs," with over 1 million people flying into LAX each day, the average Angeleno or American doesn't need to worry about Zika.
"For the general population, it's not that big of a deal," said Charsey Cole Porse, an epidemiologist at the L.A. County Department of Public Health. "It's if you're pregnant or are trying to become pregnant that you need to follow up with a provider."
Those looking to go on a Caribbean vacation, Porse said, have little to worry about. She recommended frequently reapplying bug spray with DEET and otherwise just enjoying the retreat. Where travel becomes of slightly more concern is for those planning extended stays in residential areas of Mexico, Central or South America.
"If you're staying somewhere for a longer period of time, you're probably staying in a house, not a high rise where there are [more buffers]," Porse said. "It's about just having more access to mosquitos—hanging out on the porch longer—the lifestyle changes that come with you staying somewhere longer."
But while there have been 345 cases of the Zika virus confirmed in Oaxaca, Mexico, Karin Nielsen, a professor of clinical pediatrics in the Division of Infectious Diseases at UCLA David Geffen School of Medicine said that a recent paper reported that Rio de Janeiro, Brazil, is now clear of the virus—just in time for the 2016 Summer Olympic games.
"It happens every year. By August, there are few mosquitos" Nielsen said, explaining that in the late summer month, temperatures usually drop in the country as it enters its winter. As a result, the mosquito population and the infectious diseases they spread reduce significantly.
Rio was hit by Zika three times harder than any other state in Brazil, according an April Vice News story. The city was the epicenter for the outbreak that linked the virus to microcephaly.
"Because of Brazilian surveillance," Nielsen said, "we know that of the hundreds of women recently tested, there have been no cases of Zika."
The World Health Organization has refused to endorse relocating the 2016 Summer Olympics. It says the action would not significantly alter the spread of virus which usually causes only mild outward symptoms, if any.
But when it comes to lifestyle changes, what might need to happen when Zika-infested mosquitos pop up locally? Due to the egg-laying habits of Aedes, according to Porse, vector-control, or completely eradicating the Aedes aegypti population via chemical control, would be the most effective way to respond to the mosquito if it begins transmitting the disease in California.
The rub is that chemical treatment is costly and only Aedes mosquitos need be eradicated. But mosquitos don't exactly sport name tags. One solution comes out of a partnership with UC Davis. The school has developed both a way to detect viruses in a certain mosquito, and a method to determine from mosquito eggs what type they are. Right now, Porse said, that service is free and could provide an idea of where Aedes may be and how aggressively to treat chemically.
As for the virus and its presence in California, it's nothing terribly new.
"It's existed in the forest for a long time," said Porse of Zika. "California reported six cases in the early 2000s. It's not so much that it just appeared, but more that it was the right timing of a dense mosquito population and enough infected people to really get it going.
"I think the most important thing to know right now is that Zika is spreading in Mexico, Central and South America; if you are pregnant you should not be traveling to those areas unless you have to; and if you are pregnant and have traveled to those areas you need to see your medical provider to see about testing."
Those concerned—especially in areas with already-known populations of Aedes aegypti—can keep areas around the house clear of still water and moisture, and wear clothing that loosely covers the skin when practical. And for the pregnant or super cautious? Relax, and in the words of Porse, "take a bath in bug spray."