3. Campylobacter and Pasteurella – Less famous, but just as unpleasant. These bacteria can cause digestive or respiratory infections, and cats often carry them without symptoms. That means your box can look “normal” while still harboring invisible pathogens.
4. C. difficile (C. diff) – One of the most stubborn bacteria of all. Its spores can survive on surfaces for weeks and resist most ordinary cleaners. Once stirred up, they don’t just vanish — they float, settle, and spread.
5. And even if you manage to avoid the germs, ammonia—the byproduct of urine breakdown—builds up quickly. That sharp odor isn’t just unpleasant; it’s a sign of bacterial activity that can irritate lungs and eyes, especially for kids or anyone with allergies.