Cash is on the decline and global transactions are going digital - could it be a reason to ditch paper money?

Bills change hands an average of 110 times a year, so just imagine the harbouring germs and nasty bacteria on currency surfaces. With casinos receiving millions of visitors every single year from people all over the world, we’ve taken a look at the currency coming in to find out what is really lurking on our cash.

Money with a swab

In The Lab

We gathered 20 of the most used casino currencies from around the world and partnered with microbiologists who conducted swab tests to find out what types of hidden bacteria are on our cash.

The results from the lab were fascinating, where qualitative and quantitative data was collated from the various bacterial colonies found on each note, which brought to light how different types of bacteria can impact the public. Our researchers even found strains of bacteria that cause food poisoning, pneumonia and ringworm.

The 20 filthiest banknotes

Most common bacteria:

Saccharomyces Cerevisiae can cause urinary tract infections*
Fusarisum commonly causes Keratis
Mucor racemosus causes a respiratory fungal infection
Rhizopus commonly causes Zygomycosis (Fungal Infection)
Micrococcus can cause pneumonia*
Microscope Mode

Under the microscope

Microbes cover us and everything we touch, so it is no surprise that your hard-earned cash is covered in them. With 209 bacterial colonies found, Canadian Dollars contain harmful bacteria such as Bacillus, with strains that can cause food poisoning and in rare cases, anthrax.

118 bacterial colonies on the Brazilian Real revealed Alternaria, Penicillium, Fusarium and Saccharomyces Cerevisiae. The latter, commonly known as baker's yeast, can be known to cause illnesses in the immunosuppressed such as pneumonia and urinary tract infections, as well as infections to the inner lining of the heart and abdomen.

Dropping to double figures, Hong Kong Dollars were found to have 42 bacterial colonies including Saccharomyces Cerevisiae, Penicillium, Micrococcus and Trichisporon, which is a fungus that can lead to White Piedra, a yeast infection of the hair.

Filthy money, healthy economy

The Gambling Economy in 2019

$0 - 99M

$100 - 999M

$1B +

US Map US Map

Tax Impact & Tribal Revenue Share in 2019

*Data provided by American Gaming Association is only available in states where gambling is legal.

Casino, roulette table with chips

Gambling contributes $37,035,950,000 to the US economy

The US gaming industry is vital to the country's economic health, where in 2019 alone, $37,035,950,000 was generated in gambling taxes for the US economy. As Gambling is such a lucrative industry, we looked into how much money casinos are generating in America through tax revenue and tribal revenue share.

According to's calculations, gambling comprised 4.66% of Nevada’s state GDP, where a whopping $8,270,000,000 in state revenue was generated for the Silver state in 2019. More than double California, which was the second highest state with $3,450,000,000, these figures reveal what an integral part casinos play in Nevada’s economic output.


Casino Cash

Working with the Currency Online Group our research team were able to grow and swab bacteria from twenty different paper currencies, before analyzing the results.

Bill circulation information from