Several infections can cause very high CRP levels. Bacterial infections, such as pneumonia, urinary tract infections, sepsis, and cellulitis, often result in significant inflammation and elevated CRP. Certain viral infections, like influenza or COVID-19, can also lead to increased CRP, although typically to a lesser extent than bacterial infections. Fungal infections, such as invasive candidiasis or aspergillosis, may also cause elevated CRP levels. However, it is important to note that CRP alone cannot distinguish between different types of infections, and further diagnostic tests are necessary to determine the specific pathogen causing the infection.