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Why does the rain increase our chances of catching a cold?


Why do I catch cold after getting drenched in the rain? I don't catch cold after taking shower.

What special quality does rain water have which increases the chance of getting a cold?


  • Why do I catch cold after getting drenched in the rain? I don't catch cold after taking shower.
  • What special quality does rain water have which increases the chance of getting a cold?

To answer this, let's let's first compare (describe) the two situations:

Getting caught in the rain…

  • Perhaps you were going for a run, or were walking to class, but either way you're outside, and you got caught in the rain. It's (typically) a little colder outside when raining (and windy), and because you weren't prepared, you got fairly wet all throughout your body, and will remain wet (cooler) for possibly a considerable amount of time (15+ minutes).

Getting out of the shower…

  • You're in a bathroom that's (indoors and hopefully at least somewhat) clean, and you yourself are using soaps and shampoos. Perhaps the shower water is hot (and thus the bathroom is at a higher temp by the time you get out), or even just mildly temperatured (a cold shower is fine too). When you get out of the shower, you're (maybe) shivering and cold, but you quickly (within a minute or so) get a towel and dry yourself off, thus removing the cold water. Your body starts getting warmer, and then you get dressed (which further increases body temp).


The reason why people may catch cold after being rained on and not so much after taking (colder than not) showers is because the common cold (rhinovirus) thrives better in slightly cooler tempatures. Rain lowers environmental temperatures, and, when you get rained on, that'll further contribute to a lower body temp. Also, due to the fact that you're outside and not inside, there are (probably) more environmental risks, i.e., a higher prevalency of the rhinovirus. Lastly, if you get caught in the rain then your body is (likely) going to remain colder (wet) for a longer amount of time than if you were just getting out of the shower.

To support these claims of the common cold preferring cooler tempatures, I reference a study that was published in 2014, led by Yale researcher Ellen Foxman, in which they examined the performance of temperature-dependent (immune) defenses and their ability to fight off the common cold at various temperatures. From the study:

Most isolates of human rhinovirus, the common cold virus, replicate more robustly at the cool temperatures found in the nasal cavity (33-35 °C) than at core body temperature (37 °C). To gain insight into the mechanism of temperature-dependent growth, we compared the transcriptional response of primary mouse airway epithelial cells infected with rhinovirus at 33 °C vs. 37 °C.

These findings demonstrate that in mouse airway cells, rhinovirus replicates preferentially at nasal cavity temperature due, in part, to a less efficient antiviral defense response of infected cells at cool temperature.


So, ultimately, it's because some of our bodies' defenses against the common cold are temperature-dependent, with those defenses performing more efficiently at higher temps, and less efficient at lower temps.


How Do You Catch a Cold or the Flu?

At the first sign of a cold or flu, you may wonder how it happened -- especially if you've taken steps to avoid germs. Here's exactly how you get sick, and what you need to know to protect yourself next time.

  • Viruses spread through tiny droplets in the air that are released when a sick person sneezes, coughs, or blows their nose.
  • You can get sick if you touch your nose, eyes, or mouth after you have touched something contaminated by the virus, such as a toy, countertop, or doorknob. Viruses can live on those objects for up to 2 days.
  • If you come in contact with cold or flu germs, your chance of getting sick isn’t 100%. It depends on when the other person was infected, and how many viral particles are contained in the droplets.
  • People are most contagious during the first 2 to 3 days of a cold. A cold is most often not contagious after the first week.
  • People who have the flu may pass it on to others 1 day before symptoms start and up to 5 to 7 days after getting sick, so they may spread the flu before they even know they are sick.

Sources

Charles Gerba, PhD, University of Arizona Mel & Enid Zuckerman College of Public Health.


Here’s why you’re more likely to catch a cold after getting a tattoo

If you’ve ever noticed a case of the sniffles after getting a fresh new tattoo, started panicking that you’ve somehow picked something up from the needle gun you saw coming straight from a packet, and launched into a desperate googling session, you need to read this.

First off, don’t stress. You’re (probably) not dying from a tattoo.

And no, you’re not imagining things. You are actually more likely to catch a cold after getting a tattoo.

A new study published in the American Journal of Human Biology found that those who have just had their first tattoo have a weakened immune system, and are therefore more susceptible to common colds.

Why? It’s all down to stress.

The pain of getting a tattoo can be a tough experience, putting stress on both the mind and body. As we all know, stress can reduce immune functioning. So the stress-filled tattooing process equals an increased chance of getting sick afterwards.

But here’s the good news: the more tattoos you have, the less this happens.

Researchers took saliva samples from 29 people before and after they were tattooed, analysing levels of cortisol (the stress hormone) and antibodies in the immune system.

Those with fewer tattoos had a more significant drop in antibodies – meaning reduced immune function – and a more significant increase in cortisol after getting tattooed.

But those with lots of tattoos had essentially increased their tolerance to the draining tattooing experience, meaning their antibodies didn’t drop as significantly, and they weren’t as likely to get sick as tattoo newbies.

The study’s lead author explained: ‘[Tattoos] don’t just hurt while you get the tattoo, but they can exhaust you.

It’s easier to get sick. You can catch a cold because your defenses are lowered from the stress of getting a tattoo.

‘If you continue to stress your body over and over again, instead of returning to the same set point, it adjusts its internal set points and moves higher.’

So, here’s the study’s takeaway: post-tattoo, take care of yourself and rest up. It’ll get easier the more you get.


Why does the rain increase our chances of catching a cold? - Biology

“You’ll catch your death of cold”, my grandmother always used to warn me, if I ever dared to leave the house on a winter’s day without drying my hair properly. For centuries there has been an idea across many parts of the world that you will develop a cold if you are exposed to low temperatures, particularly if you get wet as well. We even use the words “cold” or “chill” to describe the combination of a sore throat, runny nose and cough that you end up with.

But, as any doctor will tell you, the common cold is caused by a virus. So if I have just washed my hair, but I really need to leave the house urgently, should I worry about my grandmother’s warning?

Seasonal triggers

Living in Britain, I will naturally begin by examining the weather. Studies in Germany and Argentina have found a higher incidence of colds in the winter, while in warmer countries such as Guinea, Malaysia and the Gambia peaks have been found during the rainy season. We could conclude from these studies that cold or wet weather causes colds, but there is an alternative explanation. When it is freezing or raining we spend more time indoors in close proximity to other people and their germs.

So what happens when we get cold or wet? Scientists have set up experiments under laboratory conditions where they lower the temperatures of volunteers and deliberately expose them to a cold virus. But overall the studies have been inconclusive. Some studies found the chilly group were more likely to succumb to a cold, others found they were not.

However, a study conducted in a different manner offers the intriguing suggestion that there could be some truth to the saying.

Ron Eccles, director of the Common Cold Centre in Cardiff, UK wanted to know whether getting cold and damp activates the virus, which then sets off the sneezing and streaming. To do so, people were chilled under laboratory conditions, but then they returned to their real lives and mingled with people, including those who had a cold virus present in their nose or throat without becoming ill with symptoms.

Half of Eccles’ volunteers had to sit with their feet in cold water for twenty minutes, while the other half kept their socks and shoes on, but sat with their feet in an empty bowl for the same length of time. There was no difference in the cold symptoms reported between the two groups in the first few days, but four to five days later twice as many people in the cold-water group said they had developed a cold.

Lower defences

For this to make any sense there needs to be a mechanism by which getting chilled feet, or for that matter wet hair, could give you a cold. One theory is that when your body gets chilled the blood vessels in the nose and throat constrict. These same vessels deliver infection-fighting white blood cells, so if fewer white blood cells reach the nose and throat your defences against a cold virus are lowered for a short time. When your hair dries off or you go indoors your body warms up again, your blood vessels dilate, and the white blood cells continue to fight the virus. But by then it could be too late and the virus might have had enough time to replicate and trigger the symptoms.

So although we talk about “catching a chill”, the chilling has not given us the cold, but might have activated a virus already present at the back of the throat. Bear in mind though, that this area is still controversial, and Eccles’ study only demonstrated that more people who had been chilled said they had cold symptoms. No medical tests were done to confirm that they were definitely infected with the virus.

One final point is that there is a curious parallel with Norwegian health folklore, which says that women are more likely to develop cystitis when the weather is cold. Researchers found that cooling people’s feet did seem to activate cystitis in some women, suggesting that the same process might be occurring in the urinary tract, as in the blood vessels of the nose and throat.

So there might well have been some truth in my grandmother’s advice not to go out with wet hair. It will not give you a cold, as she said, but it might trigger one. In the meantime, until more research is carried out I think I will dry my hair before I go outside.

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Disclaimer
All content within this column is provided for general information only, and should not be treated as a substitute for the medical advice of your own doctor or any other health care professional. The BBC is not responsible or liable for any diagnosis made by a user based on the content of this site. The BBC is not liable for the contents of any external internet sites listed, nor does it endorse any commercial product or service mentioned or advised on any of the sites. Always consult your own GP if you're in any way concerned about your health.


Flying-fox Communication

Flying foxes use sound as a means of communication. Over 30 different types of calls have been recorded for grey-headed flying-foxes (e.g. mother/child and male/female calls). Vocal communication between individuals is necessary for identification and defence of territories.

Their hearing is similar to humans, making their calls clearly audible to our ears. Periods of noise occur mainly at dawn and dusk when the bats arrive at or prepare to leave the camp. Calls during the day occur mainly during the mating season in March/April or as a response to disturbances. These disturbances may include roaming dogs, birds of prey, planes, machinery noise (chain saws, lawn mowers, loud bangs) in or near the camp, or people walking among the roosting bats. Flying-fox noise can be minimised by preventing disturbances at the camp sites.

Flying-foxes can be heard feeding in trees at night. Noise indicates the defence of feeding territory and will cease as soon as the trees in which they are feeding finish flowering or fruiting.


Why the Myth Endures

The myth endures because it appears to people as if rainy or cold weather contributes to illness. Certainly there is a strong correlation between rainy or cold weather and viruses like cold or influenza. This is because more people are infected with these viruses during cold and/or rainy months. Plus, being outside in cold rain can cause temporary flu-like symptoms, like shivering or a runny nose. But in these cases, correlation does not imply causation. Viruses cause these illnesses, not weather patterns.


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Why do colds and flu strike in winter?

The cold and flu season is starting to rear its ugly head, and we cannot seem to get away from the coughing and sneezing. But why are we more prone to these infections during the colder months?

Share on Pinterest Most of us get at least two colds per year, but why?

Viral infections that cause the common cold or flu can range from a nuisance to a serious health threat.

According to the Centers for Disease Control and Prevention (CDC) , “common colds are the main reason that children miss school and adults miss work.”

Although most cases of the common cold and flu tend to go away by themselves, every year, flu kills an estimated 290,000 to 650,000 people worldwide.

What do scientists know about how plummeting temperatures allow these viruses to spread, and what is the best way of preventing colds and flu? We investigate.

First, we need to distinguish between the common cold and flu, because the viruses that cause these do not necessarily behave in the same way.

Most of the time, the common cold manifests with a trilogy of symptoms: a sore throat, a blocked nose, and coughing and sneezing. There are more than 200 viruses that can cause the common cold, but coronaviruses and rhinoviruses are by far the most common culprits.

There are four human coronaviruses that account for between 10% and 30% of colds in adults. These are in the same family of viruses as SARS-CoV-2, which causes COVID-19. However, it mostly causes only mild illness.

Interestingly, around a quarter of people who have an infection with a common cold virus do not experience any symptoms at all.

The flu develops due to the influenza virus, of which there are three different types: influenza A, influenza B, and influenza C.

Common colds and flu share many symptoms, but an infection with influenza also tends to manifest with a high temperature, body aches, and cold sweats or shivers. This may be a good way to tell the two apart.

As with the common cold, a significant number of people who have an influenza infection do not show any symptoms .

So, now that we know the difference between the common cold and flu, we will look at when we tend to be most vulnerable to an infection with these viruses.

The CDC monitor flu activity closely. Influenza can occur at any time of year, but most cases follow a relatively predictable seasonal pattern.

The first signs of influenza activity usually start around October, according to the CDC , and peak at the height of winter. However, in some years, flu outbreaks can stick around and last until May.

The peak month for flu activity in the seasons spanning 1982–1983 through 2017–2018 was February, followed by December, January, and March.

Other temperate locations across the globe see similar patterns, with cold temperatures and low humidity being the prime factors, according to one 2013 analysis . The same cannot be said for tropical areas, however.

In those regions, there may be outbreaks during rainy, humid months or relatively consistent levels of flu cases all year round.

This may seem counterintuitive. Indeed, although influenza data do support such a link, scientists do not fully understand how viruses are able to exert their maximum damage at both low and high temperature and humidity extremes.

There are several theories, however, ranging from the cold affecting how viruses behave and how well our immune system copes with infections to spending more time in crowded places and getting less exposure to sunlight.

Common cold and flu viruses try to gain entry into our bodies through our noses. However, our nasal lining has sophisticated defense mechanisms against these microbial intruders.

Our noses constantly secret mucus. Viruses become trapped in the sticky snot, which is perpetually moved by tiny hairs called cilia that line our nasal passages. We swallow the whole lot, and our stomach acids neutralize the microbes.

However, cold air cools the nasal passage and slows down mucus clearance.

Once a virus has penetrated this defense mechanism, the immune system takes control of fighting off the intruder. Phagocytes, which are specialized immune cells, engulf and digest viruses. However, researchers have also linked cold air to a decrease in this activity.

Rhinoviruses actually prefer colder temperatures, making it difficult not to succumb to the common cold once the thermometer plummets.

In one laboratory study, these viruses were more likely to commit cell suicide, or apoptosis, or to encounter enzymes that made short work of them when grown at body temperature.

During winter, levels of UV radiation are much lower than in summer. This has a direct effect on how much vitamin D our bodies can make.

There is evidence to suggest that vitamin D is involved in making an antimicrobial molecule that limits how well the influenza virus can replicate in laboratory studies.

Consequently, some people believe that taking vitamin D supplements during the winter months can help keep flu at bay. Indeed, a 2010 clinical trial showed that school children who took vitamin D3 daily had a lower risk of contracting influenza A.

A systematic review concluded that vitamin D provided protection against acute respiratory infection.

However, there have been no large-scale clinical trials to date, and discrepancies between individual studies make it difficult for scientists to draw firm conclusions .

Another factor that may contribute to cold and flu infections in the fall and winter months is that we spend more time indoors as the weather becomes less hospitable.

This might lead to two effects: crowded spaces helping spread viruses-laden droplets from person to person, and central heating causing a drop in air humidity, which — as we have already seen — is linked to influenza outbreaks.

However, many of us live our lives in crowded spaces all year round, and in isolation, this theory cannot explain flu rates.

Scientists continue to study seasonal patterns of respiratory infections to tease out how different factors may influence their spread.

In the meantime, what is the best way to protect ourselves from these viruses?


How a Common Cold Starts

You can catch it from another person who is infected with the virus. This can happen by direct physical contact with someone who has a cold, or by touching a surface contaminated with their germs -- like a computer keyboard, doorknob or spoon --- and then touching your nose or mouth. You can also catch it from infected droplets in the air released by a sneeze or a cough.

A cold begins when a virus attaches to the lining of your nose or throat. Your immune system -- the body's defense against germs -- sends out white blood cells to attack this invader. Unless you've had a run-in with that exact strain of the virus before, the initial attack can fail and your body sends in reinforcements. Your nose and throat get inflamed and make a lot of mucus. With so much of your energy directed at fighting the cold virus, you're left feeling tired and miserable.

One myth that needs to get busted: Getting chilly or wet doesn't cause you to get sick. But there are things that make you prone to come down with a cold. For example, you're more likely to catch one if you're extremely tired, under emotional distress, or have allergies with nose and throat symptoms.

Continued


8 Ways the Change in Weather Affects Your Body

The peskiest problems chillier temps can bring&mdashand how to avoid them.

Fall and (gulp!) winter weather doesn't just influence what you wear&mdashit can also influence how you feel. From your knee predicting it's going to rain to gasping for air during an uber-windy cold snap, here are just some of the ways your body can go haywire when the temperature changes.

"One of the causes of headaches is constriction of blood vessels in the brain," says Xiang Li, M.D., internist at Tri-City Medical Center in California. "Cold weather can cause blood vessels to quickly narrow, reducing the flow of blood." A migraine can also strike because of weather changes: Things like extreme cold, sun glare, and stormy weather can cause brain chemical imbalances that trigger a migraine. The Mayo Clinic recommends keeping tabs on your headaches and taking note of any weather-related triggers that might be causing them so you can do your best to avoid them in the future.

"As the weather cools, there's less moisture in the air, which in turn provides less moisture to the skin," says Tsippora Shainhouse, M.D., board-certified dermatologist in Beverly Hills. "Strong winds will dry and irritate the skin and potentially damage the skin's protective lipid barrier." Switch to a gentle cleanser, and exfoliate twice a week to remove the dry layer and refresh your skin.

When doing your makeup, use a primer that contains dimethicones, a silicone that prevents water loss. "Primers with silicones will seal in your moisturizer and smooth out any dry, flaking patches so that makeup goes on smoothly," says Shainhouse. And don't forget to use a humidifier in your bedroom, especially once you crank the heat. "Adding moisture to the air will help replenish moisture to your skin while you sleep," she adds.

It's thought that seasonal affective disorder (SAD) strikes during the colder months because of less light exposure during the day, says Robert S. Rosenberg, board-certified sleep medicine specialist and author of Sleep Soundly Every Night, Feel Fantastic Every Day. People who have SAD produce more of a chemical called SERT, which lowers levels of serotonin, the happy hormone. To combat feeling blah, Rosenberg recommends scoring as much light exposure as possible, whether it's through spending more time outside or using a light box (like the Sunlight Jr, $179, sunbox.com) on the reg.

"One of the primary sources of vitamin D in our body is from conversion of cholesterol stored in the skin into vitamin D3 by sun exposure," says Li. "In cold weather, not only is the UV index low, but people stay inside more and inevitably don't get enough sun." Symptoms of a deficiency include muscle weakness, greater pain sensitivity, and sleepiness. Increase your vitamin D intake by eating fatty fish like salmon and tuna, drinking fortified milk and OJ, or taking a supplement, suggests Li. The recommended dose of vitamin D3 is 600 IU per day.