New Research Shows Malaria Can Spread In Cooler Climates
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.
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.
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.
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
In Major Win for Indigenous Rights, Supreme Court Rules Much of Eastern Oklahoma Is Still a Reservation
Much of Eastern Oklahoma, including most of Tulsa, remains an Indian reservation, the Supreme Court ruled on Thursday.
- Federal Judge Orders Trump Admin to Give Native Americans Their ... ›
- Police Were Ready to Shoot Indigenous Pipeline Protesters in ... ›
- Climate Justice, Indigenous Rights Advocates Rally for Wet'suwet'en ... ›
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.
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.
- Airborne Coronavirus Transmission Must Be Taken Seriously, 239 ... ›
- Trump Halts WHO Funding Amidst Criticism of His Own Coronavirus ... ›
- Here's Why COVID-19 Can Spread So Easily at Gyms and Fitness ... ›
- Is the New Coronavirus Airborne? A Study From China Finds Evidence ›
By Angela Nicoletti
The eastern slopes of the Andes Mountains in central Perú are among the most remote places in the world.
- Global Frog Pandemic May Become Even Deadlier as Strains ... ›
- New Species of Diamond Frog Discovered in Remote Pocket of ... ›
- Frogs Are on the Verge of Mass Extinction, Scientists Say - EcoWatch ›
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.
- Trump Admin Denies Endangered Species Protections to Pacific ... ›
- Trump Admin Failed to Protect 241 Species From Extinction ... ›
- New Border Wall Construction Threatens 8 Species With Extinction ... ›
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.
Where Does the Deficiency Begin?<p>Nobody knows exactly how much vitamin D a person actually needs. The question of when a deficiency starts is correspondingly controversial. However, vitamin D is becoming increasingly popular.Not only is the pseudo-scientific literature on the "sun vitamin" experiencing an upswing, but the number of published studies has also increased enormously in recent years. For example, in 2019 <a href="https://academic.oup.com/edrv/article/40/4/1109/5126915" target="_blank">a study found that</a> Vitamin D is responsible for keeping the skeleton functional and is associated with cardiovascular diseases, type 2 diabetes and various types of cancer. <br></p>
An All-Rounder<p>Vitamin D levels in the body rise and fall according to sun exposure. If sufficient UV rays reach the skin, the body is able to produce the vitamin itself. However, the human body only derives an estimated 10 to 20 percent of its daily requirement from food.</p><p>The vitamin D that we synthesize from sunlight or food is not biologically active at first. Before the kidneys can produce the biologically active form of the vitamin, known as calcitriol, and release it into the blood, some metabolic processes must take place beforehand.</p><p>In addition, many organs have receptors to which the precursor of calcitriol binds. Further, this substance is also present in blood.</p><p>From this precursor, the organs then produce calcitriol themselves, which the body then uses for countless other processes in the body. This form of vitamin D thus regulates insulin secretion, inhibits tumor growth, and promotes the formation of red blood cells as well as the survival and activity of macrophages, which are important for the <a href="https://www.mdpi.com/2072-6643/5/7/2502/htm" target="_blank">immune system.</a></p>
Low Vitamin D, Severe COVID-19 Disease?<p>A research study carried out <a href="https://www.sciencedirect.com/science/article/pii/S2352364620300067?via%3Dihub" target="_blank">at the University of Hohenheim</a> has now established a link between vitamin D deficiency, certain previous diseases, and severe cases of COVID-19.</p><p>According to the study, "there is a lot of evidence that several non-communicable diseases (high blood pressure, diabetes, cardiovascular diseases, metabolic syndrome) are associated with low vitamin D plasma levels. These comorbidities, together with the often accompanying vitamin D deficiency, increase the risk of severe COVID-19 events."</p><p>"This statement is completely correct," said Martin Fassnacht, head of endocrinology at the University Hospital of Würzburg. However, he qualifies that it is a pure association, "i.e. a mere observation that these events occur together.</p><p>Dr. Fassnacht is very critical of the hype surrounding vitamin D, but not because he denies the vitamin serves important functions. However, studies on humans have not been able to show that vitamin D has the healing powers many often propagate.</p><p>Fassnacht says, "If you take a closer look, the hopes that the administration of vitamin D has a healing effect have not been confirmed so far."</p>
Association Versus Intervention Studies<p>Many studies on the vitamin are association or observational studies. "By definition, these studies cannot prove the causal relationship, but only point to mere correlations," said Fassnacht. The physician tries to illustrate this with an example:</p><p>"Imagine two groups of 80-year-olds. One group is spry, active and does sports. If you compare them with another group living in nursing homes, the difference in vitamin D levels will be dramatic. Life expectancy would also be extremely different."</p><p>But to try to explain the difference in fitness by vitamin D status alone is far too simplistic. "Vitamin D levels are a good measure of how sick someone is. But not more," says Fassnacht. </p><p>According to Fassnacht, none of the intervention studies carried out to date -- that specifically examined the effect of vitamin D on various diseases -- has been able to confirm the previous association and laboratory studies or the presumed positive effect of vitamin D.</p>
Further Research Is Needed<p>"If a coronavirus infection is suspected, it is therefore absolutely necessary to check the vitamin D status and quickly correct any possible deficit," said the recommendation of the paper published by the University of Hohenheim.</p><p>"Studies are underway to see whether vitamin D helps in COVID-19 infection, but I personally do not believe that this is really the case," says endocrinologist Fassnacht. Nevertheless, he says it is of course useful to carry out these studies.<br></p><p>"I don't want to rule out that there are actually subgroups of people who benefit from an additional vitamin D dose," he says. After all, this has been proven to be the case with a severe deficit.</p><p>In view of the study situation, Fassnacht does not think much of preventive, nationwide vitamin D substitutes. "My belief that the vitamin helps somewhere is very low. But, of course, I can be wrong."</p>
- 8 Ways to Tell if You Are Vitamin D Deficient - EcoWatch ›
- 7 Healthy Foods That Are High in Vitamin D - EcoWatch ›
- 7 Nutrient Deficiencies That Are Incredibly Common ›
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.
Climate models are predicting faster warming of the North Atlantic Ocean, which will shift the Gulf Stream. NASA
- Could the Climate Crisis Spell the End for Maine Lobster? - EcoWatch ›
- 5 Reasons Why Biodiversity Matters - EcoWatch ›
- World Leaders, Media Ignore Biodiversity Report Detailing Mass ... ›
- The Top 10 Ocean Biodiversity Hotspots to Protect - EcoWatch ›