The main studied aspects were risk factors in order to initial investigate relationship between severe infections and TCD4 cell depletion. Subjects and methods: Cross-sectional studies. 79 patients with severe infection and negative HIV test who were admitted at the Intensive Care Unit and Emergency Department of National Hospital for Tropical Diseases (Vietnam) from April 2017 to March 2018 were evolved in our study. Results: The mean age at diagnosis was ± years, range: 24 to 90. 60 patients (76%) were males, 19 (24%) were females. This group had many different occupations, including farmer, worker, office staff. Outside the 28 patients with a history of healthy, the risk factors were documented in 15 () with habit of smoking and/or drinking, 38 patients () had 1 to 3 chronic diseases, including 10 patients with immunodeficiency caused by pathological malignancy (7 patients), autoimmune disease (4 patients) and inborn pituitary failure (1 patient).
