GM Mosquito Progeny Not Dying in Brazil: Study

The biotech Oxitec had released the genetically engineered insects with the hope that they would breed with wild populations and produce offspring that die young. But that’s not always happening.

Sep 17, 2019


Update (September 18): Scientific Reports has issued an editor’s note, stating that “the conclusions of this paper are subject to criticisms that are being considered by editors.” In a statement sent to The Scientist, Oxitec says it takes issues with a number of conclusions the authors made in their report. Among them, “The authors infer that Oxitec’s self-limiting genes persist in the environment. Yet as confirmed by their own data, multiple other scientific studies and regulatory filings, this is not the case. Oxitec’s self-limiting genes do not establish or spread in the environment.” The journal’s note states that it will issue another response once the issues are resolved.


Afield experiment in Brazil that deployed genetically modified mosquitoes to control wild populations of the pest may be having unintended consequences. According to a genetic analysis of mosquitoes in the area, it appears the engineered stock has bred with wild mosquitoes and created viable, hybrid insects, scientists reported in Scientific Reports last week (September 10).

“The claim was that genes from the release strain would not get into the general population because offspring would die,” coauthor Jeffrey Powell, a professor of ecology and evolutionary biology at Yale University, says in a press release. “That obviously was not what happened.”

The biotech company Oxitec began releasing hundreds of thousands of genetically engineered mosquitoes in the city of Jacobina between 2013 and 2015. The idea is that genetically modified (GM) males would mate with wildtype females and pass on a gene that kills their offspring before they themselves can breed, ultimately knocking down Jacobina’s mosquito populations.

The study’s authors, who are not affiliated with Oxitec, began sampling mosquitoes in Jacobina before, during, and after the deployment of the GM insects. They created a genetic panel that distinguished the wildtype mosquitoes from the introduced ones and found that insects analyzed more than two years after the releases stopped were progeny of both wildtype and mutant, or OX513A, lineages. “The degree of introgression is not trivial,” the authors write in their report. “Depending on sample and criterion used to define unambiguous introgression, from about 10% to 60% of all individuals have some OX513A genome.”

Oxitec takes issue with Powell’s study. The company tells Gizmodo it is “currently in the process of working with the Nature Research publishers to remove or substantially correct this article, which was found to contain numerous false, speculative and unsubstantiated claims and statements about Oxitec’s mosquito technology.”

The company has reported positive results as far as reducing mosquito populations—and potentially mosquito-borne diseases—in its field sites.

Texas and Florida have considered using Oxitec’s GM mosquitoes to control populations in their states. On September 11, the Environmental Protection Agency posted a request for public comment on Oxitec’s application to release engineered insects in the Florida Keys. If approved, it would be the first deployment of the animals in the US.

Kerry Grens is a senior editor and the news director of The Scientist. Email her at

Tick ID, Testing and Reporting

Resources are Available for Tick ID, Testing and Reporting


TickSpotters help keep track of tick activity across North America (UMass Amherst)

You, and your pets can help monitor tick population trends and tickborne disease risk. TickEncounter is keeping track of tick encounters, and we need all of the TickSpotters we can get! Thousands of citizen scientists like yourself are submitting REAL data that’s helping drive tick awareness tools like TickEncounter’s Current Tick Activity app.

Tick Encounter Resource Center, The University of Rhode Island

Our Mission:  To provide a professional tick testing service to public individuals and agencies seeking more information about the risk of dangerous pathogens.

We’ve developed a battery of tests through years of research on disease-causing microbes in ticks. Since 2006, we’ve offered this expertise as service to the general public and health agency partners. Since that time, we’ve endeavored to keep costs of this testing to a minimum to allow us to serve the greatest number of subscribers. As the popularity of the service grew, the amount of data collected also grew and we now share that data as part of Tick-Borne Disease Network passive surveillance that we hope will continue to grow and provide unprecedented insights to who is being bitten by ticks, when they get bitten, and what pathogens those ticks are carrying. We welcome feedback on our web page ( and encourage everyone to SAVE THE TICKS!

Ticks and Tick-borne Diseases

Our July edition of Tree-Talk focuses on ticks and tick-borne diseases.   Our special guests this month are ANR Educators Tim McDermott, DVM (Franklin County) and Marcus McCartney (Washington County).  Check out these videos to learn how you can protect your family, pets and livestock from the increasing threat of ticks and the diseases that they carry.

Full episode (29 minutes) including Marcus McCartney’s personal experience with Lyme disease:

Protecting yourself from ticks (3:30 minutes):

Tick removal (3:41 minutes):


Useful websites:  (click on the tick tab on the top left of the page)

As Ticks Spread, New Disease Risks Threaten People, Pets and Livestock

One tick that a new study shows is endangering cattle in Virginia is able to clone itself, making colonizing new locations that much easier.

A lone star tick. To find a host, some ticks grope about with their forelegs from a leaf or grass blade, a behavior known as "questing." Credit: Smith Collection/Gado/Getty Images

Lone star ticks have been ranging farther north and west in recent years. When they bite, the aggressive ticks can spread diseases and even make humans develop a severe allergy to red meat. Credit: Smith Collection/Gado/Getty Images

It didn’t take long for one of America’s newest tick species to find Thomas Mather.

Mather, an entomologist who specializes in the tiny disease-carriers, had taken a team of scientists to Staten Island, New York, in hopes of collecting at least one Asian longhorned tick.

They were all of 50 feet from their car and had just unfurled a banner of white fabric, known as a tick drag, when the first longhorned tick landed in the fabric. Dragging a nearby patch of grass with the fabric, more longhorned ticks appeared. On a grass blade, Mather spotted an unusual clump and discovered dozens of tiny, seed-like tick larvae waiting for a victim to brush past.

If the Asian longhorned tick was unheard of in America just a few years earlier, it wasn’t a stranger here anymore.

Since 2013, the Asian longhorned tick has popped up in at least 11 U.S. states, mostly in the Northeast. Previously limited to Asia, Australia, New Zealand and some Pacific Islands, it likely found several ports of entry to North America, hitching a ride on animals or humans. Its ability to clone itself without a mate made colonizing new locations that much easier.

While the longhorned tick is still feeling out its range in North America, other established tick species are expanding theirs as the climate changes and the planet warms—with consequences for humans, pets and the livestock industry.

Several tick species have spread to new areas of the country, some carrying diseases that can pose serious health risks to humans, including Lyme disease, which can affect the joints, heart and nervous system, and Rocky Mountain spotted fever, a treatable but potentially fatal disease that causes fever and muscle pain.

An aggressive tick called the lone star, which has been creeping north and west from its original habitat, can transmit an illness similar to Lyme disease, as well as pass along a sugar molecule that can make humans develop severe allergies to red meat.

Infographic: Lonestar Tick: Its Range, Diseases and Biting Behavior

While the total number of tick-related illnesses is difficult to gauge since so many go unreported, the trend is clear. The number of cases of reported tick-borne diseases has been on the rise in the U.S., doubling from 2004 to 2016, and reached a record high in 2017, the latest annual data reported by the U.S. Centers for Disease Control and Prevention (CDC).

Higher temperature associated with climate change is one key factor affecting where, and how fast, ticks colonize new places, the National Climate and Health Assessment says.

Livestock Industry Faces a New Threat

Ticks can jeopardize animals’ health, too, and the longhorned species could become a formidable threat to the cattle industry, scientists said.

The longhorned tick is already suspected of killing cattle on farms in three separate Virginia counties by infecting them with Theileria orientalis, a parasite that causes fever, anemia, jaundice, and other symptoms in animals.

In a study published last week about the infections, researchers warned that the tick could put the Virginia cattle industry at risk. Once an animal becomes infected, there is no treatment or cure.

Infographic: Asian Longhorned Tick

Scientists warn that the longhorned tick could proliferate quickly, and since females can reproduce without a mate, ordinary ways of controlling pest population, like sterilizing males, won’t work. A single tick can populate a new location.

“As of right now, we don’t have a great way to stop that spread,” said Kevin Lahmers, a veterinary pathologist at the Virginia-Maryland College of Veterinary Medicine, who co-authored the new study, published by the CDC.

Several research teams are collaborating with the U.S. Department of Agriculture on research and surveillance of the tick, and researchers are studying the tick’s range in other countries to try to determine its potential distribution here.

Ticks in More Places

In general, ticks are expanding their ranges, Lahmers said. In Virginia, 15 to 20 years ago, Lahmers said he only saw dog ticks. Now, deer ticks—which can carry Lyme disease—are the predominant tick species there.

Infographic: Blacklegged Tick

Fluctuating climate and weather patterns can significantly affect diseases carried by ticks, as well as those carried by mosquitoes, said Ben Beard, deputy director of CDC’s Division of Vector-Borne Diseases.

With an increasing number of days without frost, for example, the risk of disease transmission starts earlier and extends later into the year. “If you look at climate change models and see how those models are advising those areas of risk, clearly there’s an impact that it’s having,” Beard said.

Infographic: American Dog Tick

In Germany, a tropical tick called hyalomma seems to have survived its first winter there, according to Ute Mackenstedt, a professor of parasitology at the University of Hohenheim, Stuttgart. Her team discovered the tick this year too early in the season to have been brought over by migrating birds.

“We expect new ticks species in Germany due to changing weather conditions,” Mackenstedt said. She said the hyalomma tick could become the second recently introduced species typically found in warmer conditions to establish a population in Germany, though it’s too early to be sure.

Hyalomma can transmit the Ebola-like Crimean-Congo hemorrhagic fever virus, though that virus hasn’t yet been found in Germany.

Preventing Tick Bites — at Home and in the Woods

The longhorned tick is able to spread a virus known as SFTS, or severe fever with thrombocytopenia syndrome. It can be fatal, particularly for people over 50, but it hasn’t yet turned up in the U.S.

The CDC urges precaution against all tick species, not just the longhorned.

“There’s a huge potential here for this tick to further complicate the problems we’re already having,” said Beard of the CDC. “It’s one of those things we can’t afford to ignore, but at the same time, we have to work on the problems that are already here.”

Crowd-Sourcing Tick Research

Several research efforts are gathering data about the spread of ticks from people who photograph or mail in ticks they’ve found. Mather runs one of those efforts, a website through the University of Rhode Island called TickSpotters, where his team of researchers fields questions from people who submit photos and samples to be analyzed.

He said there’s been a clear increase in submissions over the past few years: From the site’s inception in 2014 until 2017, he saw fewer than 8,000 entries. Last year alone, he saw nearly 15,000.

Infographic: Rocky Mountain Wood Tick: Its Range, Diseases and Behavior

One reason may be that ticks are spreading to new places. Mather said contributors frequently ask, “What’s going on? I’ve lived in this place for 15 years and never seen a tick before.”

Building a database of these findings can help researchers understand tick distribution patterns.

“It’s people that are encountering ticks a lot more than scientists,” Mather said. “TickSpotters has a chance for using the power of the crowd to help understand what’s going on.”

Ohio Vector-borne Disease Update 07/12/2019

As of 07/11/19, 5,389 of 5,642 pooled mosquito samples (170,866 Culex spp. total) have been tested and 7 samples were positive for West Nile virus (WNV) from Franklin (5), Ross (1) and Summit (1) counties. Below is a graph of the minimum infection rate (MIR) in Culex spp. mosquitoes collected in Ohio. As you can see, the MIR is below where it was at this time last year. No human cases have been reported so far.

While WNV activity in Ohio is currently low, in the past week, several suspected cases of La Crosse virus disease have been reported. Although these cases are pending confirmatory testing, this suggests La Crosse virus activity is ongoing in Ohio. Please ensure you continue with your community and public education efforts focusing on personal protection to avoid mosquito bites and source reduction to prevent mosquito breeding.

For more information, see the current Ohio vector-borne surveillance update at

NOTE: Since Internet Explorer is no longer being supported, ODH’s new webpage is best viewed in other browsers (e.g. Microsoft Edge, Google Chrome, Firefox, etc.).

Please do not hesitate to contact the Zoonotic Disease Program (614-752-1029, option 1) if you have any questions.

The Tick App

April 22nd, Earth day, The Tick App – 2019 will be available in GooglePlay and iTunes!

Who are we? 

This study is conducted by researchers from Columbia University and the University of Wisconsin – Madison, members of the CDC Regional Centers for Excellence in Vector-Borne diseases. Funding for this study is provided by the Centers for Disease Control.

What is the study about?

In two words, Lyme disease. Lyme disease can be transmitted to humans after a tick bite. This study is designed to help us understand more about how  people’s practices and activities impact their exposure to ticks. This research is being done because Lyme disease is the most common vector-borne disease (infections transmitted by the bite of infected arthropod species, such as mosquitoes, ticks, sandflies, etc) in the United States. The information provided will help us design integrated control strategies to prevent diseases transmitted by ticks.

Why is my participation important and how is the app useful to me?

If you live in a high-risk area, sharing your experience and perspective with us will help us learn about the risk factors for tick borne disease and design better methods that prevent tick bites and tick-borne disease. We really appreciate your input!

We are also including information that will help you identify the different tick species, ways to prevent tick exposure and other information that will help you understand more about ticks and the diseases they transmit.

How can you help us?

Once you download the app and register for an account, you will be asked to take one enrollment survey that will help us capture your baseline risk of exposure to ticks.

You will then receive a weekly to monthly message to start your tick diary during the high risk months (May to September). The tick diary, or activity report, should take less than a minute to complete. It asks if you or a household member encountered a tick and what you did that day. When you start the tick diary, you will receive a daily reminder until you complete 15 reports.

Also, you can help us by reporting any tick through a quick form built in the app.

If I don’t want to use the app, how can I participate?

You can sign-up in our website and the surveys will be sent to your email. The informational material can also be found in this website


West Nile Virus: Case Update

As of 8/20,2018, ODH is reporting 5 human West Nile virus (WNV) cases, including 1 fatality, and 2 asymptomatic WNV viremic blood donors in Ohio.  Additionally, ODH received a report today from the Ohio Department of Agriculture of an equine case in an unvaccinated horse.  WNV activity in mosquitoes continues to rise and we have now seen indications of virus activity in 52 Ohio counties so far this year.

The graph below shows where we are this year with infection rates in mosquitoes compared to 2012, a high WNV activity year (red dotted line), and 2016, a relatively normal WNV activity year (green dashed line):

In addition to WNV, ODH is also reporting 6 LAC cases and 2 unspecified California virus cases.  The rainfall we’ve had this summer has continuously filled tree holes and containers with water, creating ideal conditions for tree hole mosquitoes (vectors of LAC virus) to breed. For more information about arbovirus cases and surveillance data, see the current Ohio arbovirus surveillance update at, updated earlier today.

There are quite a few weeks left in this  mosquito season and cases can occur into October, so it is very important to continue your community and public education efforts focusing on personal protection and source reduction. Also, please call the Zoonotic Disease Program (ZDP) at (614) 752-1029 if you have any questions.

A New Tick Species Found in the United States

You probably have heard about this new tick invasive in the U.S. First detected in late 2017 in NJ. Recent reports are that it is spreading rapidly. See news clips as below:

“For the first time in 50 years, a new tick species has arrived in the United States — one that in its Asian home range carries fearsome diseases.

The Asian long-horned tick, Haemaphysalis longicornis, is spreading rapidly along the Eastern Seaboard. It has been found in seven states and in the heavily populated suburbs of New York City.

For now, the new arrivals are considered a greater threat to livestock.

Known in Australia as bush ticks and in New Zealand as cattle ticks, long-horned ticks can multiply rapidly and suck so much blood from a young animal that it dies.

The longhorn tick is known to carry several diseases that infect hogs and cattle in Asia. So far, ticks examined in the U.S. do not carry any diseases that can infect humans, but the USDA says the insects frequently form large infestations that cause great stress on warm-blooded host animals, reducing its growth and production. A severe infestation can kill the animal due to blood loss.


Officials said female longhorn ticks reproduce asexually and a single tick can reproduce and lay 2,000 eggs after feeding on a host. Cattle, pets, small mammals, birds and humans are all potential hosts.


In 2017, officials discovered the first longhorn tick population in the United States feeding on large numbers of sheep in Mercer County, New Jersey. It has also been found in Arkansas, New York, West Virginia and Virginia. Tests by the National Veterinary Services Laboratory in Ames, Iowa, have confirmed the presence of an Asian — or longhorn — tick on a wild deer in Centre County on Tuesday. It is the first confirmed sighting of the parasite in Pennsylvania.”

West Nile Virus Activity Continues to Increase

West Nile virus activity continues to increase and the statewide mosquito infection rate as of week 27 (week of July 4) is trending with infection rates we saw in 2012, our last epidemic year when we recorded 122 human cases.  No human cases have been reported this year yet; however, 2 asymptomatic viremic blood donors were reported this past week, so there is evidence human infections have occurred. If you haven’t already, please be sure to increase your community and public education efforts focusing on personal protection and source reduction.

Here is a graph that shows where we are this year as of week 27 with infection rates in mosquitoes compared to 2012, an epidemic WNV year (blue line), and 2016, a relatively average WNV year (orange line):

For more information, see the current Ohio arbovirus surveillance update at  The data on this website was last updated on 7/16/18 and will be updated each Monday thru mosquito season. Please call the Zoonotic Disease Program (ZDP) at (614) 752-1029 if you have any questions.