Shrinking forests are giving mosquitoes a greater taste for human blood, study suggests
Joao Paulo Burini/Getty Images
(NEW YORK) — As forests shrink and wildlife disappears, mosquitoes are increasingly turning to people for their blood meals, a shift that raises real concerns about the potential spread of diseases that affect humans.
A new study published in the journal Frontiers suggests these buzzing, biting insects are playing a growing role in the increased transmission of Zika, yellow fever, dengue and other diseases that mosquitoes pass on to people, thanks in part to disappearing habitats.
Deforestation, which is the widespread clearing of forests, and other human activity has vastly reduced local populations of plants and animals while increasing human populations in the same areas, according to the study.
“Mosquitoes that are normally feeding on other hosts within the habitat can shift to humans if the habitat is no longer suitable for those hosts and they leave,” Laura Harrington, a Ph.D.-level professor of entomology at Cornell University, told ABC News.
Human blood was widely found in nine types of mosquitoes in two formerly uninhabited areas in the state of Rio de Janeiro, Brazil, preliminary study results found. This area was once a part of the Atlantic Forest that covered 502,000 square miles. Today, it has shrunk to 29% of its original size as a result of deforestation and development, according to the final study.
The researchers point to past studies showing that areas with heavier deforestation have a higher mosquito abundance and higher rates of mosquito-borne disease because disturbed habitats favor species that thrive near people. At the same time, reduced biodiversity removes animals that can dilute disease transmission, making humans more likely to become the primary blood source.
Sérgio Lisboa Machado, a co-author of the paper and a professor at Federal University of Rio de Janeiro in Brazil, said mosquitoes are opportunists who don’t venture far to find food.
“So they start searching for humans because mosquitoes rarely fly very long distances,” he told ABC News. “They are not going to pay a lot of energy to find [other food sources].”
More than 17% of all infectious diseases are caused by vector-borne diseases, meaning a disease that’s transmitted to humans by a living organism, such as mosquitoes, ticks, and flies, the World Health Organization (WHO) reports. These biting insects cause more than 700,000 deaths globally.
Mosquitoes alone transmit dozens of serious diseases to humans, according to the WHO, which consequently considers them the deadliest animals on Earth.
Female mosquitoes are the culprit. They must drink blood to get the protein and iron they need to develop their eggs, according to the Centers for Disease Control and Prevention.
There is a “reproductive drive for them to feed on blood, and if there’s no other host there, most mosquitoes would feed on a human,” Harrington told ABC News.
Male mosquitoes buzz, but they don’t bite, instead dining on nectar and plant sugars.
There are 3,500 mosquito species globally, Harrington said, noting that there are only a handful that truly prefer the taste of human blood over other animals. When given a choice, only a small fraction of mosquito species regularly seek out humans.
“It’s something that we’ve known for a long time,” Harrington said. “This notion that manipulating the landscape can alter mosquito feeding patterns and sometimes shift feeding patterns towards humans.”
(PORTLAND, Ore.) — Two people were injured in a shooting involving a federal agent in Portland, Oregon, on Thursday, according to authorities.
The incident came a short time after an ICE officer allegedly shot and killed a woman in her car in Minneapolis, Minnesota, sparking outrage and backlash against the presence of federal agents there. Similarly, the mayor of Portland called for immigration enforcement operations to halt while the investigation is ongoing.
In both cases, federal officials said the motorists tried to ram agents, who fired defensive shots.
The Department of Homeland Security said the shooting in Portland occurred while Border Patrol agents were conducting a “targeted” stop on a vehicle carrying two people allegedly affiliated with the Tren de Aragua gang. The passenger was the target, DHS said.
The agents on the stop were part of a Customs and Border Protection operation dubbed “Operation Oregon,” according to multiple law enforcement sources.
“When agents identified themselves to the vehicle occupants, the driver weaponized his vehicle and attempted to run over the law enforcement agents,” DHS said in a statement.
The driver, who was not the target of the operation, was stopped driving a red Toyota, before they attempted to flee. The agent, as DHS said in their statement, feared for their safety and fired at the vehicle.
Sources stressed the information and investigation are in its preliminary stages and the information could change.
The two that were shot, were treated at a hospital for their injuries and their conditions are unknown, according to law enforcement sources. Both are believed to be connected to the Tren de Aragua gang, according to DHS.
During the press conference, Portland Police Chief Bob Day said local officials “do not know the facts of this case,” but an investigation is ongoing.
Asked whether the passenger is linked to a previous shooting, the police chief said, “I can’t comment on whether or not that’s the case. We don’t know who these individuals are.”
Portland Mayor Keith Wilson told reporters, “We know what the federal government says happened here. There was a time when we could take them at their word. That time is long past.”
“We are calling on ICE to halt all operations in Portland until a full and independent investigation can take place,” he said. “Our community deserves answers.”
Later Thursday evening, Oregon Attorney General Dan Rayfield said he was opening an investigation into the shooting.
In a social media post, Rayfield said the Oregon Department of Justice investigation will examine whether any federal officers acted outside the scope of their lawful authority during the encounter. The post said the investigation would include witness interviews and video evidence.
The shooting incident occurred around 2:18 p.m. local time on Thursday, officials said. Portland police officers responding to a call for help found a man and woman with “apparent gunshot wounds,” according to the police department.
“Officers confirmed that federal agents had been involved in a shooting,” the Portland Police Department said in an earlier statement, adding, “Portland Police were not involved in the incident.”
The shooting occurred some 3 miles away from where the victims were found, on the 10200 block of Southeast Main Street near Adventist Health, a medical office, according to Portland police. The victims then drove themselves to an apartment complex in the area of Northeast 146th Avenue and East Burnside Street, where the man who had been shot called for help, according to police.
The FBI was seen in video responding to the scene of the shooting. Portland police are assisting, a department spokesperson said.
Police Chief Day urged calm amid “heightened emotion” following a deadly ICE officer-involved shooting in Minneapolis on Wednesday.
“We are still in the early stages of this incident,” Day said in a statement. “We understand the heightened emotion and tension many are feeling in the wake of the shooting in Minneapolis, but I am asking the community to remain calm as we work to learn more.”
During the press conference, Oregon Gov. Tina Kotek called for transparency from the federal government in the investigation.
“The priority right now is a full, completed investigation, not more detentions. My message to the federal government is this: We demand transparency. We demand your cooperation with Portland Police and the Multnomah County DA, because we need to investigate this incident efficiently and effectively so we can rebuild trust with our nation’s government,” Kotek said.
Earlier, Mayor Wilson called the incident “deeply troubling” while also calling on residents to “show up with calm and purpose during this difficult time.”
“Portland does not respond to violence with violence,” he said in a statement. “We respond with clarity, unity, and a commitment to justice. We must stand together to protect Portland.”
Early Friday, Portland police confirmed that at least six people were arrested during protests as crowds gathered outside an ICE facility.
“At about 9 p.m., officers requested that people move to the sidewalk, as traffic remained open in the area. An officer in the PPB Sound Truck, a loudspeaker-equipped police vehicle, broadcast that request repeatedly to the group,” the Portland Police bureau said in their statement. “PPB moved in and made targeted arrests resulting in five custodies,” while another arrest was made later on.
Multnomah County District Attorney Nathan Vasquez told reporters at the scene of the shooting that he is “very concerned.”
“We are here from this attorney’s office to monitor, to assist and to make sure that there’s a thorough and complete investigation, that evidence is fully preserved, and that we’re certainly hoping that we can get all of the facts about what transpired,” he said.
This is a developing story. Please check back for updates.
An F/A-18E Super Hornet, attached to Strike Fighter Squadron 151, prepares to make an arrested landing on the flight deck of Nimitz-class aircraft carrier USS Abraham Lincoln in support of Operation Epic Fury, March 2, 2026. (U.S. Navy)
President Donald Trump’s special envoy Steve Witkoff revealed in an interview this week that Iranian negotiators told him in the lead-up to the U.S.-Israeli military operation in Iran that they had enough enriched uranium to “make 11 nuclear bombs.”
But since the major combat operations were launched on Saturday with the intent of crushing Iran’s nuclear ambitions, the administration has yet to publicly produce any concrete evidence on the whereabouts of the nuclear material or who is in control of it. The Israel Defense Forces claimed that at least 40 top military commanders were killed in the opening strikes of the conflict.
In an interview on Fox News, Witkoff told host Sean Hannity that as soon as he and Trump’s son-in-law, Jared Kushner, sat down with the Iranian negotiators for denuclearization talks last month, their counterparts spoke of their stockpile of enriched uranium.
“Jared and I opened up with the Iranian negotiators telling us they had the inalienable right to enrich all the nuclear fuel they possessed,” Witkoff said. “We, of course, responded that the president feels we have the inalienable right to stop you in your tracks.”
Witkoff claimed the Iranian negotiators openly shared details about their supply of nuclear material.
“In that first meeting, both the Iranian negotiators said to us directly with, you know, no shame, that they controlled 460 kilograms of 60% [enriched uranium] and they’re aware that that could make 11 nuclear bombs,” Witkoff said.
Witkoff said the 60% enriched uranium can be brought to weapons-grade in about a week and that the 20% enriched uranium can be brought to weapons-grade in three to four weeks.
“They manufacture their own centrifuges to enrich this material,” Witkoff said. “So, there’s almost no stopping them. They have an endless supply of it.”
The statement appears to contradict what the Pentagon said last summer about Iran’s ability to develop weapons-grade uranium following U.S. strikes on its nuclear facilities.
In July 2025, Sean Parnell, the Pentagon’s chief spokesperson, said at a news conference that that the strikes on Iran’s nuclear facilities in June set back Iran’s capability to develop a nuclear weapon by “closer to two years.”
“It’s not just … enriched uranium or centrifuges or things like that. We destroyed the components that they would need to build a bomb,” Parnell said at the time.
But on Tuesday, that assessment fell to the wayside as the administration defended the U.S. military operation by insisting Iran posed an imminent threat to Americans. A senior administration official told reporters in a briefing that among the factors in the operation was that Iran had the ability to rebuild those components destroyed in the bombing, including its own centrifuges.
The official said a lot of the enriched uranium remained mostly in Isfahan with some still at Natanz and Fordo.
“It can be a long and cumbersome process in extracting it and covering it up,” the official said. “I think the first question is, where is it? The second question is, how do we get to it, and how do we get physical control? And then after that, it would be a decision of the president and department, the Department of War, CIA, as to whether we wanted to physically transport it or dilute it on premises.”
Iran has stated numerous times that it doesn’t want nuclear weapons, but believes it has the right to use nuclear power for civilian purpose. It had also been part of a nuclear deal with the U.S., which Trump withdrew from during his first term.
Iranian Foreign Minister Abbas Araghchi told ABC’s “This Week” anchor George Stephanopoulos on Sunday that the attack on his country was “unprovoked and unwarranted.” He said Iran was negotiating with the United States in good faith prior to the attacks.
“A deal was at our reach, and we left Geneva happily with the understanding that we can reach a deal next time we meet,” Araghchi said.
In their two public briefings on “Operation Epic Fury” in Iran, Secretary of Defense Pete Hegseth and Gen. Dan Caine, chairman of the Joint Chiefs of Staff, did not address what has become of Iran’s nuclear material since the widespread military strikes began on Saturday.
In several speeches since the attacks commenced, Trump has also not been specific about the status of Iran’s nuclear material.
Hegseth, Caine, CIA Director John Ratcliffe and Secretary of State Marco Rubio conducted a closed-door briefing with members of the U.S. Senate and House on the Iran operation on Tuesday afternoon.
In a letter sent on Monday to the administration’s briefers, five top House Democrats — including Rep. Gregory Meeks of New York, ranking member of the House Foreign Affairs Committee, and Rep. Adam Smith, ranking member of the House Armed Services Committee — asked for information on nuclear security in Iran.
“Who currently controls Iran’s nuclear facilities and materials, and what safeguards are in place to prevent diversion or proliferation, or complete loss of control?” the Democratic lawmakers asked in their letter.
But following the briefing, Meeks said the briefers offered few answers.
“Here we are again without answers. Here we are again without complete transparency,” Meeks said. “Here we are again trying to go around Congress.”
Pramila Jayapal, D-Wash., said the briefers provided “no additional” information on the imminent threat that prompted the military operation, adding, “There’s nothing that we got that you don’t have.”
House Speaker Mike Johnson, R-La., challenged any suggestion that the Trump administration was unclear during their briefing with House members about their objectives in Iran.
“This is really a very simple matter. It’s about the building of ballistic missiles. That’s what Iran was engaged in, and they were doing it at a speed and in a scale that was exceeding the ability of our regional allies to respond appropriately,” Johnson said. “This created an imminent and serious threat. It also gave them cover to continue with their nuclear ambitions.”
Johnson added, “As you know, we tried very hard to negotiate with them about that nuclear enrichment of uranium … and the buildup of their missiles was so important and so serious that the President of the United States, this president, thought that it was a great enough threat that we needed to act.”
The International Atomic Energy Agency (IAEA), the United Nations’ nuclear watchdog, said in a social media post on Tuesday that, based on the latest available satellite imagery, it “can now confirm some recent damage to entrance buildings of Iran’s underground Natanz Fuel Enrichment Plant [FEP].”
“No radiological consequence expected and no additional impact detected at FEP itself, which was severely damaged in the June conflict,” the IAEA said in the post.
In June 2025, the U.S. and Israeli militaries launched “Operation Midnight Hammer,” targeting three of Iran’s nuclear facilities — Natanz, Fordo and Isfahan — with “bunker-buster” bombs, according to the White House.
At the time, Trump said the operation “completely and totally obliterated” Iran’s key uranium enrichment sites.
In a speech on Monday at the White House, Trump said that after “Operation Midnight Hammer,” Iran attempted to rebuild its nuclear facilities in another location, “because they were unable to use the ones we so powerfully blew up.”
“In addition, the regime’s conventional ballistic missile program was growing rapidly and dramatically, and this posed a very clear, colossal threat to America and our forces stationed overseas,” Trump said. “The purpose of this fast-growing missile program was to shield their nuclear weapon development and make it extraordinarily difficult for anyone to stop them from making these highly forbidden, by us, nuclear weapons.”
The Institute for Science and International Security said in a statement on Tuesday that its analysis of satellite imagery indicates the Natanz nuclear complex, Iran’s main uranium enrichment site, was struck twice during Saturday’s joint U.S.-Israeli attack.
Neither the Trump administration nor the Israeli government have confirmed the alleged strikes on the Natanz complex.
Meanwhile, Israel targeted a compound near Tehran linked to the regime’s nuclear weapons “capabilities,” the Israel Defense Forces (IDF) said in statement Tuesday.
After the U.S. targeted Iran’s nuclear facilities last year, Israel, which participated in the operation under the code-name “Rising Lion,” continued to track scientists connected to the Iran’s nuclear weapons program “and located their new location at this site in a manner that enabled a precise strike on the covert underground compound,” the statement said.
“The strike removes a key component in the Iranian regime’s capability to develop nuclear weapons and joins a series of strikes conducted during Operation ‘Rising Lion’ that were essential to eliminate the Iranian nuclear threat,” the IDF said.
-ABC News’ Mary Kekatos and Jordana Miller contributed to this report.
Badwater Basin, the site of Lake Manly, is viewed from Dante’s View showing the lake receding due to evaporation on April 21, 2024, near Furnace Creek, California. (George Rose/Getty)
(DEATH VALLEY NATIONAL PARK, Calif.) — An ancient lake that once existed at Death Valley National Park has reemerged after record rainfall in the region.
Several inches of water have formed in Badwater Basin, which lies at 282 feet below sea level, the lowest point in North America, according to a press release from the National Park Service.
During the Ice Ages, the basin — colloquially known as Lake Manly — was once a lake with depths of up to 700 feet.
Ice covered the Sierra Nevada between 128,000 and 186,000 years ago, allowing rivers to flow into a long valley that fed into Lake Manly, according to NASA. At the time, the lake measured nearly 100 miles long.
In modern times, the basin typically lies bare, without any significant moisture.
Death Valley just experienced its wettest fall on record, according to the National Weather Service. Between September and November, 2.41 inches of rain fell — more than what typically falls in the desert landscape in one year. November alone recorded 1.76 inches — breaking the record set in 1923 at 1.7 inches.
The lake is much more shallow than the one that formed in 2024 in the aftermath of Hurricane Hilary — an event that prompted the first tropical storm watch in California’s history.
On Aug. 20, 2024, alone, more than 2 inches of rain fell in Death Valley, according to the NPS.
This year’s rainfall will allow those who missed the last emergence of Lake Manly to see the rare phenomenon once again.
The water can’t drain out, since the basin is contained and at such a low elevation, said Andrew Heltzel, chief commercial officer of the Xanterra Travel Collection, an operator of lodges, restaurants and excursions at several of the most iconic national parks in the U.S., including Death Valley, Yellowstone and Grand Canyon.
“It’s almost impenetrable,” Heltzel told ABC News, describing the outskirts of the basin as “like a seal.”
The only way for the water to escape is through evaporation, which could take months.
When the water is present, it creates a stunning reflection of the surrounding mountain peaks.
“My advice would be to, if you are interested in seeing this, not to delay to get there,” Heltzel said. “It is getting smaller through evaporation every day.”
The “most exciting” aspect of the way the rain fell this time is that it could spark a superbloom of wildflowers in the spring, Heltzel said.
The pace and amount of rain that fell made for the “perfect ingredients” for a significant display of wildflowers to emerge, Heltzel said.
In 2024, too much rain fell too fast, and the soil was unable to absorb the moisture, Heltzel said.
“With the November rains, they came in gently enough that it was able to get into the ground and potentially give us those flowers as well as a second chance to see Lake Manly,” he said.
The last time a superbloom occurred was in 2016, according to the NPS.
The recent storms caused numerous road closures across the parks, with several paved roads covered in flood debris, according to the NPS. However, many of the park’s most popular sites remain open, including Zabriskie Point, Dantes View, Badwater Basin, and Mesquite Sand Dunes.
The National Park Service advised visitors to be aware that unpaved roads may be impassable due to storm damage and to be prepared for self-rescue when traveling on backcountry roads.
In February, Death Valley National Park will host the Dark Sky Festival, which can give visitors opportunities to sky gaze while also seeing Lake Manly, Heltzel said.
Death Valley has been designated as a Gold Tier Dark Sky Park, which signifies the highest rating of darkness, according to the NPS.
“The stargazing opportunities in Death Valley are second to none,” Heltzel said.
