Prospective case-control analysis of the aetiologies of acute undifferentiated fever in Vietnam

Le-Viet, Nhiem; Le, Viet-Nho; Chung, Hai; Phan, Duc-Tuan; Phan, Quang-Duong; Cao, Thanh-Van; Abat, Cédric; Raoult, Didier; Parola, Philippe

All patients who met the eligibility criteria during the study period were continuously enrolled. AUFs were included in this study if they fulfilled four primary criteria: (i) age ≥15 years; (ii) axillary temperature ≥38°C; (iii) duration of fever ≤21 days [60] ; and (iv) no evidence of localized infection based on history, initial physical examination, complete blood count, chemistry profile, urinalysis or chest radiography. Some patients who presented with several sporadic symptoms (e.g. cough, sore throat, breathlessness, diarrhea, and abdominal pain) that were not consistent with physical examination results in a clinical diagnosis were also included in the study. We excluded dengue fever and malaria because these diseases are well known to be common causes of febrile illness in Vietnam, and their diagnostic tests are available in almost all hospitals in Vietnam. Thus, we excluded patients who tested positive for malaria on a peripheral blood smear (Giemsa stained thick and thin films) or for dengue on RDTs for nonstructural 1 glycoprotein (NS1) antigen/IgM. We also excluded patients with other conditions that could bias the results, such as receiving cancer chemotherapy or immunosuppressive therapy, having HIV infection, and hospitalized for ≥72 h within the preceding 30 days. HIV testing was not performed routinely. We performed HIV ELISA testing only for patients who had never been tested for HIV infection if their clinical symptoms and signs suggested an immunosuppression condition. To ensure a complete follow-up during the illness course, only inpatients with AUF admitted to infectious disease wards were considered for this study.