"The longer the nail, the more surface area there is for microorganisms to adhere," said Jeffrey Kaplan, a biology professor at American University.
"Studies have found 32 different bacteria and 28 different fungi underneath fingernails."
And whether they’re artificial nails, long natural nails, gel nails, acrylic nails or just nail polish, they increase the probability that microorganisms lurk underneath them, which in turn makes it more difficult to wash off with simple handwashing, Kaplan added.
He noted one study that found that a resistant bacteria, known as methicillin-resistant Staph aureus, or MRSA, in half of fingernail samples, which could subsequently lead to an infection.
"You can transmit fingernail bacteria to your system by scratching, nail-biting, nose-picking and finger-sucking," Kaplan said.
The bacteria and fungi underneath the long nails can also lead to a nail infection, which could leave the fingernails disfigured.
In 1997-98, after an Oklahoma City hospital investigated an outbreak of Pseudomonas aeruginosa, a bacteria acquired often in the hospital setting, epidemiologists discovered a link between approximately half the 16 infants who died in the neonatal unit and the bacteria under long fingernails, according to the New York Times.
The hospital subsequently imposed measures that prohibited long nails in the neonatal intensive care unit.
"A growing body of evidence suggests that wearing artificial nails may contribute to transmission of certain healthcare associated pathogens. Healthcare workers who wear artificial nails are more likely to harbor gram-negative pathogens [like Pseudomonas] on their fingertips than are those who have natural nails, both before and after handwashing," according to the Centers for Disease and Prevention.
So the agency recommends that artificial nails should not be worn by health care workers who have direct patient care with high risk patients, like in the intensive care unit, and their nail tips be kept to one-fourth inch in length.
"Long nails are a perfect hideout for pathogens, including viruses and bacteria, that get trapped under there," said Dr Cristina Psomadakis, a dermatologist based in the U.K. and popular on Instagram as "Dr. Soma."
"I also recommend clear polish or translucent finishes on nails. This allows us to be able to see when our nails are dirty and serves as a visual reminder to wash our hands."
But nail technician Kayla Newman, who is based in North Carolina, said none of her clients had any infections in her eight years of practice.
"Generally people who have long nails know how to maneuver with them and keep them clean," she said.
"If you're spending upwards of $60 to get your nails done and you don't keep them clean, that doesn't make sense."
She recommends for those with long nails to make regular appointments because the nail strength may shift as they grow with broken nails as the most common complaint – especially those new to them.
"Nails are an awesome luxury to have," she said.
"I encourage people to get them done because when you look at your hands and see them nice and done whether they are long or short, it makes you feel amazing."