One of the top stories of 2016 quietly exited much of the public’s consciousness in 2017. But it’s still a hot topic among scientists and for good reasons. After Zika emerged in the Western Hemisphere, it shook the Americas, as reports of infections and devastating birth defects swept through Brazil and Colombia, eventually reaching the United States. In a welcome turn, the number of Zika cases in the hemisphere this year dropped dramatically in the hardest-hit areas.
But few scientists are naïve enough to think we’ve seen the last of Zika. “The clock is ticking for when we will see another outbreak,” says Andrew Haddow, a medical entomologist at the U.S. Army Medical Research Institute of Infectious Diseases in Frederick, Md.
Researchers’ to-do list for tackling this once-unfamiliar virus is daunting. But progress has been made, especially in learning more about Zika’s biology and interactions with its hosts, and in developing a safe and effective vaccine.
In 2017, the epidemic lost steam because many areas have probably developed herd immunity to the virus (SN: 11/11/17, p. 12). Zika infected a large number of people, who are now presumably immune, and those exposed provide indirect protection to people who haven’t yet encountered Zika. If the mosquito-borne virus can’t find enough people to infect, it can’t easily spread.
But Zika doesn’t rely only on mosquitoes to get around. This year, researchers learned more about how the virus spreads through sexual intercourse. In humans, Zika can persist in semen for close to three months, researchers learned. And Haddow and colleagues reported in the August Emerging Infectious Diseases that four of eight macaques exposed to the virus vaginally developed infections as did seven of eight macaques that received the virus via the rectum.
In 95 percent of people tested, Zika RNA is cleared from the blood by 54 days after symptoms begin, and urine by 39 days. In 95 percent of men tested, Zika RNA disappears from semen by 81 days. Few people in the study had detectible levels of Zika RNA in saliva or vaginal secretions.
In the wild, animals can act as reservoirs for Zika between human outbreaks. A small number of black-striped capuchin monkeys and common marmosets in a region of Brazil with high numbers of human cases were found to carry the virus already, the first such report among New World monkeys. But there’s still a lot to learn about how the virus is maintained long-term in nature, Haddow says.
Convinced that Zika is here to stay and especially concerned about its effects during pregnancy, researchers have rushed to develop vaccines. In its first test in humans, reported online October 4 in the New England Journal of Medicine, one vaccine based on DNA from the virus elicited an immune response, with 100 percent of participants developing antibodies after a three-dose regimen. Another DNA vaccine, developed by the National Institute of Allergy and Infectious Diseases in Bethesda, MD, is in a second round of human testing.
Attention to the virus may wane further. But the risk to public health remains, and interventions are still needed, such as ongoing monitoring that tracks Zika and other infectious diseases in pregnancy, says Denise Jamieson, an obstetrician gynecologist at Emory University School of Medicine in Atlanta. “We’re not ready for another emerging infectious disease that may disproportionately affect pregnant women or their fetuses or babies,” she says. “And we need to be.”
Source: Science News
Zika virus cases skyrocketed from 103 just before the quake to 1,275 confirmed cases in Ecuador 10 weeks after the disaster, with 86 percent of all new cases occurring near the Manabi epicenter
A public health study has found a link between psychological distress and people experiencing Zika-like symptoms in areas hardest hit by Ecuador’s 2016 earthquake, particularly among women between the ages 40 and 60 years.
The city of Bahia de Caraquez in Ecuador’s Manabi province was rocked by a 7.8 magnitude earthquake on April 16, 2016. The region’s weak infrastructure and lack of preparedness resulted in high rates of mortality and morbidity and significant damage to buildings, roads and water supply.
At least 660 people died, with a further 30,200 displaced and 720,000 left in need of humanitarian assistance. More than 9,700 buildings were reported damaged or destroyed.
Survivors were forced to sleep outside in makeshift tents and store water in open tanks, placing them under increased psychological stress.
A joint study by the Ecuadorian Department of Health; the SUNY Upstate Medical University in Syracuse, NY; and the University of California San Francisco in Sacramento concludes the conditions caused a spike in incidents of the Zika virus and other vector-borne diseases, such as dengue fever.
Zika virus cases skyrocketed from 103 just before the quake to 1,275 confirmed cases in Ecuador 10 weeks after the disaster, with 86 percent of all new cases occurring near the Manabi epicenter.
Scientists, led by Anna Stewart-Ibarra, director of the Latin American Research Program for the Center for Global Health and Translational Science at SUNY Upstate Medical University, found that nearly 10 percent of interviewees suffered from a variety of Zika virus or dengue fever symptoms. Of those, more than 58 percent were suffering fear or anxiety.
The study, published in the International Journal of Environmental Research and Public Health, concludes that women between 40 and 60 years old still not sleeping in their own homes three months after the quake reported the highest incidences of Zika symptoms and mental distress.
Middle-aged women shoulder the most responsibility for their families in Ecuador, the study found, with female community leaders feeling doubly responsible to care for their neighbors. These social factors, along with the environmental conditions, likely decreased the ability of their immune systems to fight off the virus.
Director Stewart-Ibarra told teleSUR: “The earthquake in Ecuador triggered PTSD [post-traumatic stress disorder], lowering people’s immune systems because of stress.”
She said very few researchers are “looking at how mental health and infectious diseases interact in post-disaster settings.”
She also noted that such studies, of which there are very few, are important because “we see more and more extreme natural disasters, especially climate-related natural disasters.”
In early results published in the Lancet, researchers report that an investigational Zika vaccine was well-tolerated and stimulated potentially protective immune responses in three phase 1 clinical trials, one of which was conducted at Saint Louis University. More than 90 percent of study volunteers in the 3 trials who received the investigational vaccine demonstrated an immune response to Zika virus. Spread primarily by Aedes mosquitoes and also by sexual contact, Zika infection of pregnant women can put babies at risk of developing microcephaly, characterized by underdeveloped heads and brain damage, and other serious health issues. An investigational vaccine against the virus, called ZPIV (Zika Purified Inactivated Vaccine), was developed by the Walter Reed Army Institute of Research (WRAIR), in partnership with the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health (NIH), and the Biomedical Advanced Research and Development Authority (BARDA), part of the Office of the Assistant Secretary for Preparedness and Response (ASPR), both at the U.S. Department of Health and Human Services (HHS).
The three placebo-controlled, double-blind trials were designed to address different questions researchers wanted to answer about the immune responses elicited by the investigational vaccine.
The SLU study continues its enrollment, examining how three different vaccine doses compare in terms of safety and ability to stimulate an immune response. A trial conducted by WRAIR is examining the impact of priming the immune system with either a licensed yellow fever or Japanese encephalitis vaccine followed by ZPIV vaccination. Beth Israel Deaconess Medical Center (BIDMC) is evaluating three dosing schedules of ZPIV.
Principal investigator of the SLU trial Sarah George, M.D., is encouraged by the study findings.
“I’m happy to see our work help make progress toward a vaccine against Zika,” said George, who is associate professor of infectious diseases, allergy, and immunology at Saint Louis University. “We need a vaccine to protect people from this emerging infectious disease that can cause microcephaly and other severe brain defects in babies.”
This work was supported in part by a cooperative agreement (W81XWH-07-2-0067) between the Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc., and the U.S. Department of Defense (DOD). This research was also funded, in part, by NIAID.
SLU’s Center for Vaccine Development is one of nine Vaccine and Treatment Evaluation Units selected in 2013 by the National Institutes of Health to study vaccines that aim to protect people from infectious diseases and emerging threats. The project is funded under Contract No. HHSN272201300021I. The federal government has funded vaccine research at SLU since 1989. More information about the Zika clinical trial is available on clinicaltrials.gov.
Mosquitoes are, by far, the deadliest animals on Earth. More than 725,000 people die from mosquito-borne illnesses like malaria each year, and millions are affected by mosquito-borne illnesses, according to the World Health Organization.
Now new technology is being used to try to reduce mosquito-borne illnesses. In particular, introducing sterile male mosquitoes to a population can increase competition for female mosquitoes, eventually reducing the population by as much as 90 percent, according to researchers.
But introducing the mosquitoes to areas affected by mosquito-borne diseases can be a challenge.
“Not everybody lives next to a road. Even if roads do exist in some of these areas, they look very different when the rainy seasons hit. … And of course when it rains … you have pools of standing water and even more mosquitoes,” says Patrick Meier, executive director and co-founder of WeRobotics, a nonprofit with offices in the US and Switzerland.
“What we’re doing that nobody else has done is to make it such that we release these mosquitoes from the air, using affordable drones,” Meier says.
In partnership with the International Atomic Energy Agency (IAEA) Insect Pest Control Lab in Vienna, Austria, WeRobotics is testing out the technology and hopes to put it to use in Zika hotspots in Latin America.
But releasing hundreds of thousands — if not millions — of mosquitoes comes with engineering challenges, Meier says.
“How do you take 100,00 mosquitoes, put [them] in a relatively small box and have them not kill each other?” Meier says. “You have to keep the mosquitoes in a kind of sleep state, which means you reduce the temperature within this ‘box’ between 4 and 10 degrees celsius.”
Other challenges include releasing mosquitoes in a uniform manner, Meir says. “You’re not releasing 100,000 as soon as you get to 400 feet. You’re trying to do a homogenous release over a gridded area. Remember, these mosquitoes are basically knocked out, if you’d like, or tranquilized. How do you ensure that as they’re falling from the release mechanism, they actually wake up in time before they go splat on the ground?”
WeRobotics will begin deploying these drones in the coming months, focusing on communities that are already deploying sterile mosquitoes on the ground, and providing education to locals about the project.
“This is frankly our bread and butter — training, awareness-raising, capacity-building and informing local communities can be used, and are being used, to improve their health,” Meier says.
Other methods to reduce mosquito-borne illnesses range from simple nets and vaccines to mass spraying of insecticides, but many have proved ineffective, costly, and damaging to the environment.
Source: Public Radio International