Quantcast
Environmental News for a Healthier Planet and Life

Help Support EcoWatch

New Research Shows Malaria Can Spread In Cooler Climates

Climate
Pixabay

By Marlene Cimons

For nearly a century, scientists thought that malaria could only spread in places where it is really hot. That's because malaria is spread by a tiny parasite that infects mosquitoes, which then infect humans — and this parasite loves warm weather. In warmer climates, the parasite grows quickly inside the mosquito's body. But in cooler climates, the parasite develops so slowly that the mosquito will die before the it is fully grown.


At least that was the prevailing understanding. New research suggests parasites don't mind the cold as much as scientists thought.

It appears that parasites can thrive in slightly cooler temperatures that were once believed to be inhospitable for them. This means that slightly warmer weather in more temperate regions could prompt parasites to reach their full potential—a situation that will put thousands or more people in danger of contracting malaria. Not only will rising temperatures spur mosquitoes to move to new areas that were formally too cold to inhabit, hotter weather will also nurture the growth of the disease-carrying parasites that live inside those mosquitos.

"Our results show that not only is it possible for the mosquito to become infectious with malaria parasites at cool temperatures, but that it happens considerably faster than has been previously thought," said Jessica Waite, a senior scientist at Penn State and a co-author of the study with Matthew Thomas, professor and Huck scholar in ecological entomology at Penn State. Their findings could help predict the spread of malaria in cooler climates. The paper, which also included researchers from the University of Exeter, appears in the journal Biology Letters.

Aedes albopictus, also known as a tiger mosquito.

Pexels

Malaria is a life-threatening illness caused by Plasmodium parasites that are carried by the female Anopheles mosquito, and passed on to humans through her bite. More than 400,000 people died of the disease in 2017, with sub-Saharan Africa bearing the largest brunt of malaria cases — more than 90 percent — according to the World Health Organization. It is also a problem in parts of South America and South Asia, according to the Centers for Disease Control and Prevention (CDC).

Malaria was eradicated from the United States in 1951, largely due to effective control measures, such as spraying and air conditioning. Today, only around five people a year die of malaria in the United States. Most of those infected with malaria contracted the disease while traveling, according to the CDC. "It is unlikely that developed countries with active detection and prevention programs, such as ours, would ever become areas of active malaria transmission again," Waite said.

The disease typically begins with fever, chills and headache, but can lead to death if untreated. "I'm not a medical doctor, but anecdotally I've heard it makes people feel pretty miserable — like a bad flu with cyclic fevers," Waite said. It is particularly dangerous for small children and "can lead to coma and death for severe infections," she said.

Cases of malaria by country in 2017.

WHO

The researchers wanted to know how long it took for mosquitoes to become infectious, believing that older studies were flawed, including some that relied on a Russian species of mosquito."We wanted to get some good data to improve models," Waite said. This is especially important, she said, in places wear mosquitos might thrive if it were only a little warmer.

For example, "imagine a mountain, and at the peak of the mountain, it's too cold for mosquitoes to live or for parasites to complete their transmission cycle," she said. "However, at the base of the mountain there is a lot of malaria and mosquitoes." Many people live between the base and the peak and could become vulnerable to malaria if it becomes just a little bit warmer in those areas, she said.

In conducting their study, scientists infected mosquitoes in the lab with human malaria parasites. They did this by feeding them blood containing the parasite. The blood was held in place by a layer of waxy, stretchy film. "The mosquitoes pierce through this material like they would for human skin and take up a blood meal with the parasites," she said, explaining the experiments.

A mosquito feeding.

Pixabay

After the mosquitoes finished dining, the scientists placed them into different incubators, some warm, some cold. They exposed some mosquitoes to fluctuating temperatures — as in nature, where it's cool at night and warm at midday — and others to constant temperatures. They then dissected them and examined their guts and salivary glands, looking for malaria parasites.

Open an infected mosquito and you will find bags filled with replicating parasites. When these bags burst, the parasites will spill out and find their way to the mosquito's salivary glands. Infected mosquitoes then pass on these parasites to humans when they draw blood. It takes time for the parasites to grow and then make their way to the salivary glands — but not as much time as was previously thought.

"So, for example, at [64 degrees Fahrenheit] the [earlier] model would predict mosquitoes become infectious at around 56 days, but we found at constant temperatures infectious mosquitoes were found as early as 33 days," Waite said. "With fluctuating temperatures — similar to real world conditions — this was as fast as 27 days. This makes a big difference because mosquitoes don't live forever."

Thus, if climate change continues to cause cooler regions to get warmer — even just a little bit — mosquitoes will get a jump start toward becoming fully infectious before they die. Waite is counting on that not happening. "I'm hopeful our work will lead to better estimates of malaria spread, and better prevention strategies," she said.

Reposted with permission from our media associate Nexus Media.

EcoWatch Daily Newsletter

Much of Eastern Oklahoma, including most of Tulsa, remains an Indian reservation, the Supreme Court ruled on Thursday. JustTulsa / CC BY 2.0

Much of Eastern Oklahoma, including most of Tulsa, remains an Indian reservation, the Supreme Court ruled on Thursday.

Read More Show Less
The Firefly Watch project is among the options for aspiring citizen scientists to join. Mike Lewinski / Wikimedia Commons / CC by 2.0

By Tiffany Means

Summer and fall are great seasons to enjoy the outdoors. But if you're already spending extra time outside because of the COVID-19 pandemic, you may be out of ideas on how to make fresh-air activities feel special. Here are a few suggestions to keep both adults and children entertained and educated in the months ahead, many of which can be done from the comfort of one's home or backyard.

Read More Show Less
People sit at the bar of a restaurant in Austin, Texas, on June 26, 2020. Texas Governor Greg Abbott ordered bars to be closed by noon on June 26 and for restaurants to be reduced to 50% occupancy. Coronavirus cases in Texas spiked after being one of the first states to begin reopening. SERGIO FLORES / AFP via Getty Images

The coronavirus may linger in the air in crowded indoor spaces, spreading from one person to the next, the World Health Organization acknowledged on Thursday, as The New York Times reported. The announcement came just days after 239 scientists wrote a letter urging the WHO to consider that the novel coronavirus is lingering in indoor spaces and infecting people, as EcoWatch reported.

Read More Show Less
A never-before-documented frog species has been discovered in the Peruvian highlands and named Phrynopus remotum. Germán Chávez

By Angela Nicoletti

The eastern slopes of the Andes Mountains in central Perú are among the most remote places in the world.

Read More Show Less
Left: Lemurs in Madagascar on March 30, 2017. Mathias Appel / Flickr. Right: A North Atlantic right whale mother and calf. National Marine Fisheries Service

A new analysis by scientists at the Swiss-based International Union for Conservation of Nature (IUCN) found that lemurs and the North Atlantic right whale are on the brink of extinction.

Read More Show Less
Nobody knows exactly how much vitamin D a person actually needs. However, vitamin D is becoming increasingly popular. Colin Dunn / Flickr / CC by 2.0

By Julia Vergin

It is undisputed that vitamin D plays a role everywhere in the body and performs important functions. A severe vitamin D deficiency, which can occur at a level of 12 nanograms per milliliter of blood or less, leads to severe and painful bone deformations known as rickets in infants and young children and osteomalacia in adults. Unfortunately, this is where the scientific consensus ends.

Read More Show Less

Trending

Data from a scientist measuring macroalgal communities in rocky shores in the Argentinean Patagonia would be added to the new system. Patricia Miloslavich / University of Delaware

Ocean scientists have been busy creating a global network to understand and measure changes in ocean life. The system will aggregate data from the oceans, climate and human activity to better inform sustainable marine management practices.

EcoWatch sat down with some of the scientists spearheading the collaboration to learn more.

Read More Show Less