Clinically, many pulmonary nodules, need to be differentiated from infectious diseases. Infectious diseases of the lung are a large group of diseases including, viral infections, bacterial infections, fungal infections (Aspergillus infections, Cryptococcus infections, etc.), tuberculosis infections, nontuberculous branch infection infections, parasitic infections, etc. 1, if there is a history of pastoral contact, especially raw beef and mutton, or raw freshwater fish (raw food in the Japanese restaurant does not count), you need to be highly suspicious of parasitic infections, in this case, you can go to the Shanghai Institute of Parasitology to take blood tests for parasitic antibody tests, the address is next door to the Shanghai Ruijin Hospital General Hospital. The blood test costs about several hundred yuan. 2.If someone in your family has TB, or a relative or friend has TB, and there is close contact, you can consider sputum test for TB, PPD, T-SPOT test, or XpertMTB/RIF test if you have high suspicion. PPD and T-spot are only exclusionary diagnoses, and a positive sputum test only indicates past exposure to TB or a history of TB infection, but does not prove that the nodules in your lungs are TB. The value of these two positive indicators is not significant, and the value of negative indicators is to prove that the nodules in your lungs are not caused by tuberculosis. 3, viral infection in the lung, such as influenza virus, chickenpox virus, new coronavirus, are formed in the lungs, the lung formed in the short-term grinding glass shadow, recent fever patients, there may be a viral infection. 4, bacterial infection, with recent fever symptoms and solid nodules or patchy nodules in the lungs, such patients can be considered for review and evaluation after anti-inflammatory treatment. Usually, blood tests suggest elevated white blood cells, elevated neutrophil ratio, and elevated CRP. 5, fungal infection clinical routine check G test, GM test, cryptococcal latex agglutination test (blood test, the cost of several hundred yuan, about 1-2 days can produce results), these tests, if positive, suggesting a fungal infection, you can use antifungal treatment, without surgery. To summarize, in clinical work, if pulmonary nodules need to identify infectious diseases 1, the tests that can be considered include: sputum check for tuberculosis bacteria, G test, GM test, cryptococcal latex agglutination test. 2, PPD, T-SPOT test is not a routine test, and the clinical diagnostic significance of the test is not significant, so it is not recommended to do it routinely. 3, a high degree of suspicion of tuberculosis, can do XpertMTB/RIF test 4, a high degree of suspicion of parasitic infection, can draw blood to check parasitic antibodies 5, lung nodules, especially the size of relatively small nodules, routine tumor marker test, and 7 tumor marker test is not very meaningful, the probability of meaningful positive is very low, but often there is a meaningless elevation, bringing unnecessary anxiety to patients It is better not to check. Lung nodules, especially those of small size, are routinely tested with these blood tests, which have a low probability of positivity, mainly for exclusionary diagnosis and to avoid preoperative misdiagnosis. Solid nodules larger than 1 cm can be considered for PET if they are not absorbed after anti-inflammation and are routinely negative for infectious agents.