Opportunistic etiological agents causing lung infections: emerging need to transform lung-targeted delivery
Parasites And Staphylococcus: How Hygienic Are Public Swimming Pools Really?
From tropical parasites to bacterial pathogens, here's what else might be swimming in the water.
It might just serve as a way to pass a rainy afternoon, but swimming may be one of humans' oldest hobbies. The earliest swimming pool dates back to 3000 BCE, in the Indus Valley.
Much later, in the 19th Century, swimming pools emerged in Britain and the US. But along with them came the challenge of keeping them hygienic. Even now, public – and private – swimming pools can become hotbeds of infection if they're not well maintained.
So, just in time for the season of summer swimming (in the northern hemisphere, at least), here's what else might find its way into the pool water with you.
Which bacteria do we swim alongside?
But most of the time, enteric diseases (the ones that cause diarrhoea and vomiting) clear up on their own in healthy people, says Jackie Knee, assistant professor in the London School of Hygiene and Tropical Medicine's Environmental Health Group. However, they can be a bigger concern for young children, the elderly and people who are immunocompromised, she adds.
Swimmers can catch cryptosporidium when an infected person has a faecal accident in the pool, or from swallowing residual faecal matter from their body, Knee says.
"And they could still shed [the parasite] afterwards, when they're not experiencing symptoms anymore," says Ian Young, associate professor at Toronto Metropolitan University's School of Occupational and Public Health in Canada.
You may go to many lengths to avoid swallowing pool water, but evidence suggests that some still ends up in our bodies.
Early swimming pools were mostly kept clean by refreshing the water regularly (Credit: Getty Images)
One 2017 study conducted at public swimming pools in Ohio involved testing the blood of 549 people, including adults and children, after swimming in pool water for one hour. On average, the adults swallowed around 21 mL per hour, while children swallowed around 49 mL per hour.
When swallowed, the chances of this water being an infection risk differs depending on how busy the pool is. One study found that contracting cryptosporidium is more likely when swimming at peak times. The researchers tested water from six pools once a week for 10 weeks in summer 2017, and detected cryptosporidium in 20% of the pool samples, and at least once in each pool. Two thirds of these water samples were during the pool's busiest times, in the school holidays.
But cryptosporidium isn't the only thing to watch out for, says Stuart Khan, professor and head of the School of Civil Engineering at the University of Sydney in Australia.
Infections from opportunistic bacteria, such as Staphylococcus, can infect the skin, he says, and there is also the potential to contract fungal infections in swimming pool changing rooms, since these pathogens survive longer in warm, damp environments.
Another common bacterial infection that can be contracted from swimming pools is swimmer's ear, says Khan, which is usually caused by water that stays in the outer ear canal for a long time. However, this isn't spread from person to person.
It's possible to contract infections through inhalation, too. For example, legionella bacteria may be present in swimming pools. When breathed in through air droplets, can cause the lung infection Legionnaires disease.
However, outbreaks of most infectious diseases linked to swimming pools are rare. "We don't see too many outbreaks of waterborne illnesses in public swimming pools, which means it's done well enough a lot of the time with chlorine disinfection, but occasionally have some outbreaks happening," says Young.
How are bacteria managed in swimming pools?
Before the 1900s, swimming pools didn't have a chemical disinfectant. Some filtered or changed the water frequently, while some pools were built on a slope to help drainage, or fitted with a type of gutter to scoop away visible impurities.
"Traditionally, public bathing sites were either in the ocean where the water was naturally refreshed, or fresh water like a river where there's tidal movement," says Khan.
While swimming pools have occasionally been associated with disease outbreaks, wild swimming also carries risks (Credit: Getty Images)
In rare cases, it's possible to get bacterial infections from swimming pools, such as from pathogens including Campylobacter, Shigella and Salmonella. In most cases these bacteria cause gastrointestinal symptoms such as diarrhoea and stomach cramps, as well as fever. However, they can also lead to serious complications. Thankfully, much of the risk is mitigated by chlorine, says Khan.
In order to maintain this level of protection against viruses and bacteria, a pool must be well controlled, says Khan. This involves ensuring that the water is the right pH and alkalinity to allow the chlorine to be effective, he adds.
Also, the amount of chlorine required depends on how many people are in the pool at any given time. "The higher the chlorine demand, the more you need to put in. There's quite a science to it," Khan says.
Regulations around public swimming pool maintenance differ between countries. In the UK, there are no specific health and safety laws, but operators must comply with the Health and Safety at Work Act. In the US, swimming pools can be regulated at both federal and state level. While the US Centers for Disease Control and Prevention (CDC) has a health and safety code for pools, it is voluntary.
"The cryptosporidium parasite is extremely tolerant to chlorine," says Knee. "Most other pathogens are killed within minutes, but cryptosporidium stays alive and active for more than a week at normal levels of chlorine treatment."
This is because of how the parasite is structured. "It can go into spore formation, where it wraps itself up tightly and prevents anything touching the exterior, which makes it resistant to lots of things," says Khan.
The risk of infection is likely highest from bigger and more obvious accidents in the pool, but this risk can be mitigated if responded to immediately, says Knee. Pool operators can either use a coagulant and filter the pool water – if they have an appropriate filtration setup that doesn't filter the water too quickly – or use 'super chlorination', Knee says. The latter involves adding much higher levels of chlorine to the water and leaving it for a longer period of time.
To minimise the risk of infection, it's important that pools are well-maintained (Credit: Getty Images)
But while these incidents are pretty obvious, people can shed faecal material passively without it being a massive event, Knee says.
Are there other risks in the pool?
You may be surprised to learn that the unmistakable smell of chlorine that hits you when you come out of the changing room and into the swimming pool actually isn't technically the smell of chlorine.
"This smell is when chlorine is reacting to other materials, particularly ammonia, in the water, which comes from urine and sweat," Khan says. This ammonia reacts with chlorine and forms chloramine, which is what causes the smell.
Swimming in other environments
With so many unwanted guests washing around the water of swimming pools, it might be tempting to consider wild swimming instead – perhaps a spot of bathing in a lake, river or the sea. But there are well-documented infection risks here too. Some water bodies contain untreated sewage, for example, or they can be contaminated with animal faeces.
"So, the smell suggests that there are bodily fluids in the pool reacting with the chlorine," says Khan.
These chloramines hover above the surface of the water and inhaling them can cause irritate our throats and eyes, says Young. "Chemicals that cause irritations and degrade the quality of chlorine in the pool can affect everyone's health," he says. "Just a short amount of exposure can affect you."
What can be done to minimise your risk when swimming?
The risk of chloramines forming above the water can be lowered by ensuring that everyone showers before entering the pool, says Yong, which helps to wash off faecal matter. Showering can help to lower the risk of spreading and contracting infection, says Knee.
Yong also emphasises the importance of a pool having good ventilation.
Busy pools must be monitored particularly carefully, to prevent the water becoming contaminated (Credit: Getty Images)
Other important ways to avoid infections from swimming pools include avoiding swallowing pool water, says Knee – as the pathogens that cause diarrhoea are transmitted by ingesting water contaminated with poo.
Knee adds that it's important to quickly alert pool operators to contamination events and exit the pool immediately.
The CDC suggests that those with pools can lower the risk of infection by regularly draining and replacing water, maintaining chlorine and pH levels within certain ranges, as well as scrubbing the pool surfaces to remove any slime.
On balance, Knee and Khan both agree that the health and social benefits of swimming outweigh the risk of infection.
"Properly maintained pools that are properly treated and have operators who know how to jump into action when there is a contamination event pose minimal risk to health, in terms of infectious disease risk," Knee says.
So, there are plenty of reasons to take a dip this summer – just make sure you take a shower, too.
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Staph Infection Vs. MRSA: Differences, Symptoms, Treatment
Staphylococcus aureus is a bacterium that commonly grows on the skin. If levels become too high, a staph infection may develop. Methicillin-resistant Staphylococcus aureus (MRSA) causes a type of staph infection that can be hard to treat due to antibiotic resistance.
Both MRSA and non-MRSA staph infections share similar features, including appearance, symptoms, causes, and risk factors. The main difference is what antibiotics will work against MRSA versus other staph infections.
Doctors may refer to non-MRSA staph infections as methicillin-sensitive staph infections (MSSA).
This article discusses the similarities and differences between other staph infections and MRSA.
About 30% of adults have Staphylococcus aureus in their noses. Comparably, about 5% of patients in United States hospitals carry MRSA in their nose or skin.
For most people, this bacterium can live on their noses without causing any health problems. Those most at risk of developing an infection from Staphylococcus aureus include individuals who have:
MRSA is a type of Staphylococcus aureus that is resistant to antibiotics. Like regular staph infections, it typically causes skin infections that can appear as small red bumps similar to a spider bite.
Both MRSA and staph infections start as skin infections that can spread from the skin to other areas of the body. They can also transmit easily from person to person.
Certain locations and activities can increase an individual's risk of developing either type of infection. Common areas in which people should take extra precautions include:
In these environments, a person should take care to avoid scrapes or cuts. If they do occur, they need to make sure they clean their wound thoroughly with soap and water.
The appearance of MRSA and staph infection can vary between people. Additionally, it will likely be impossible from looks alone whether a skin lesion is due to staph, MRSA, another infection, or something else, such as a spider bite.
Since MRSA simply means the staph infection is resistant to methicillin, there may not be a difference in its appearance compared to another type of staph infection.
In either case, a doctor will often need to run tests to determine if the infection is from Staphylococcus or other bacteria. Tests may include a wound culture, which uses a skin sample, tissue, or fluid to determine the type of bacterium causing the infection.
Staphylococcus is the group of bacteria responsible for staph infections, with Staphylococcus aureus being the most common form. The main difference is that non-MRSA generally responds well to a variety of antibiotics, while MRSA may only respond to a few, making it harder to treat.
Spreading via contact
Staph infections spread primarily from contact with a wound carrying an infection or sharing personal items with someone with the infection, including razors and towels.
Risk factors
People who inject drugs have a rate of contracting a serious staph infection 16 times that of individuals who do not. Other common risk factors of both types of infection include:
Staph infections typically start on the skin, but they can spread to other areas of the body without treatment.
When a staph infection affects only the skin, it can cause symptoms according to the impacted skin areas. The following are some symptoms of a staph infection depending on how they affect the skin:
The CDC adds that an MRSA infection may have the following symptoms at skin level:
These symptoms also appear with non-MRSA infections. This is because MRSA refers to these infection types that do not respond to certain antibiotics — it does not indicate that the symptoms differ between the two types of staph infection.
If a person does not seek treatment for staph infection or MRSA, or the infection worsens, it can spread to other areas of the body. When the infection becomes invasive, it can cause the following issues and symptoms:
An individual may not be able to tell whether their skin infection is the result of a staph or MRSA infection.
They should seek medical care as early as possible to prevent complications. A person who notices signs of a possible staph infection should:
Treatments will vary according to the severity, location, and type of infection. For some topical infections, a person may find that applying warm compresses and keeping the area clean is enough to care for the lesions.
In some cases, a doctor may need to use an incision and drainage to treat the lesion. During the procedure, a healthcare professional will use a sterile scalpel to create a cut and then drain the pus from the lesion.
However, if the infection gets worse, a person should speak with their doctor about additional treatment options. Often, first-line treatment may involve topical ointments with antibiotics or oral antibiotics.
If the infection is severe, a healthcare professional may recommend an antibiotic injection.
In cases of MRSA, a doctor will need to use alternative medications that are effective against antibiotic-resistant infections.
MRSA is a type of staph infection that is resistant to certain antibiotics. The main difference is that an MRSA infection may require different types of antibiotics.
MRSA and staph infections have similar symptoms, causes, risk factors, and treatments. Treatment options can include warm compresses, drainage, topical antibiotics, oral antibiotics, or antibiotic injections.
With treatment, a person should see a full recovery. However, if the treatment is delayed or not effective, staph infections can develop into serious illnesses.
ByteDance Mass Food Poisoning: Catering Company Pleads Guilty
ByteDance had catered lunch for its employees on Jul 30 last year. The meal was served at the canteen at One Raffles Quay and involved food from Yunhaiyao and another caterer.
Sixty people who consumed the meal prepared by Yunhaiyao suffered from abdominal pain, diarrhoea and vomiting, and were taken to different hospitals.
SFA's National Centre for Food Science confirmed that the chicken dish prepared by Yunhaiyao was the likely cause of staphylococcus aureus food poisoning in the victims.
A day after the incident, SFA inspected Yunhaiyao's food preparation premises and discovered a cockroach infestation.
More than 10 live cockroaches were found beneath a folded grey plastic mat behind a rack on Yunhaiyao's premises. Staff members immediately disposed of the infested material, the prosecutor said.
SFA prosecutor Mohd Rizal asked for a total fine of S$5,500 (US$4,300) for Yunhaiyao. This is the company's first offence.
However, District Judge Janet Wang adjourned sentencing, saying more information was needed as the extent of harm caused "is not clear".
She said there is "huge public interest in this case" and asked for information including the extent of the injuries to the victims, how many required medical intervention, how many were hospitalised and how many were given hospitalisation leave.
Mitigation and sentencing was adjourned to Jul 17.
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