Why did the penny lickers spread TB in England?

Penny lickers were individuals in 19th-century England who licked the remnants of food from coins to collect a small profit. This unsanitary practice contributed to the spread of tuberculosis (TB) as the coins, often contaminated with bacteria, facilitated the transmission of the disease. Additionally, the close quarters and poor living conditions of many penny lickers exacerbated the spread of TB, a highly contagious respiratory illness. The combination of these factors made them a vector for infection during that time.