Lung carcinoma is one of the most common cancers and the leading cause of cancer-related death worldwide. Increasing evidence has shown that Cryptosporidium spp., an opportunistic parasite, is associated with cancers, causing life-threatening infections. The most common clinical form of Cryptosporidium is intestinal infections. However, respiratory cryptosporidiosis has rarely been documented, although the parasite infects respiratory epithelial cells and gastrointestinal (GIS) epithelial cells. To evaluate respiratory cryptosporidiosis in patients with lung cancer, we investigated Cryptosporidium spp. in patients with lung cancer (n = 69) in comparison with healthy groups (n = 40). Sputum and stool samples were examined microscopically and by polymerase chain reaction (PCR). Two cancer patients were diagnosed with respiratory cryptosporidiosis (2.9%), on PCR examination of the sputum samples. Cryptosporidium spp. was detected in the stool samples of one patient (1.5%) and 2 healthy individuals (5.4%) by PCR and microscopy. First, respiratory cryptosporidiosis was documented in 2 patients with lung cancer. Cryptosporidium is an important agent of the respiratory tract and GIS infections in cancer patients. These new findings highlight the molecular prevalence of Cryptosporidium spp., an opportunistic infection, in patients with lung cancer. Respiratory cryptosporidiosis should also be considered when patients have respiratory symptoms.
Keywords: Cryptosporidium spp.; PCR; lung cancer; respiratory cryptosporidiosis.