Objective Despite strict surveillance, Neisseria meningitidis still causes life-threatening invasive meningococcal disease (IMD). The study aimed to describe the prevalence, clinical and subclinical features, and treatment outcomes of IMD among young soldiers of the Vietnam People’s Army. Methods A prospective, population-based surveillance study was conducted in all Vietnamese military hospitals from January 2014 to June 2021. The presence of Neisseria meningitidis was confirmed by PCR or culture from blood or/and CSF. Epidemiological indices (incidence, serogroups, and distribution of cases by length of service), medical history, clinical and sub-clinical features, and treatment outcomes were documented and analyzed. Results There were 69 IMD cases (91% serogroup B) documented, mainly in conscripts (91%). The highest annual incidence was 3.33/100,000 soldiers per year. Of these cases, 44% were meningitis (n=30), 19% septicemia (n=13), and 38% meningococcemia (n=26). The most common clinical symptoms were neck stiffness (61 cases, 88%), petechial rash (51%), and shock (20 cases, 29%). Laboratory findings showed leukocytosis in 96% of IMD cases, PCT >0.05 (ng/mL) in 100%, elevated leukocyte count (>1,000/mm3) in 71%, and high protein >1 g/L in 70%. The overall mortality rate was 9%. Two cases were found to be resistant to ceftriaxone. Prognostic factors of severity included petechial rash (OR = 9.82, p < 0.001), septicemia (OR = 5.83, p < 0.001), meningococcemia (OR = 6.22, p < 0.001), low platelet count, prolonged prothrombin time; high PCT (AUC = 0.84, p < 0.001), and increased creatinine (AUC = 0.86, p < 0.001). Conclusion IMD remains a health threat in the armed forces in Vietnam, especially among new recruits. To the best of our knowledge, this is the first study in Vietnam describing ceftriaxone resistance in Neisseria meningitidis and suggests the need to reconsider standard empiric therapy for IMD.

Introduction: Rickettsioses are diseases caused by intracellular Gram-negative bacteria of the Rickettsiaceae family and transmitted through the bite of infected ticks or mites. Aim of Study: To investigate the clinical and subclinical characteristics and prognostic severe factors of the disease caused by Rickettsiaceae. Methods: A prospective, descriptive cross-sectional study was conducted at Department of Infectious Diseases of two military hospitals in Northern Vietnam from May 2013 to June 2019, in which 88 adult febrile patients caused by Orientia tsutsugamushi (50 patients) or Rickettsia spp. (38 patients) were enrolled. We recorded information regarding epidemiological characteristics (age, geography, residence, occupation), medical history, clinical and subclinical findings, life-threatening complications during treatment, outcomes and some factors predicting serious life-threatening complications in a case record form. Results: Scrub typhus (ST) patients had eschar (70%), skin-conjunctiva congestion (60%) and lymphadenopathy (44%). Rickettsia patients had a higher rate of maculopapular rash (39.5%), no ulcers and no lymphadenopathy detected. The majority of patients had elevated PCT >0.05 ng/µL and increase in liver enzymes and thrombocytopenia. Major prognostic factors for severe complications included diffuse infiltrates on lung X-ray (OR: 19.5; p = 0.014), coarse crackles (OR: 18; p = 0.016), respiratory rate ≥25 cycles/minute (OR: 18; p = 0.016), shortness of breath (OR: 7.44; p = 0.003), pleural fluid (OR: 4.3; p = 0.035) and increase in AST ≥ 200 UI/l (OR: 4.42; p = 0.012). The PCT value is able to distinguish between the two groups with quite high reliability (the area under the ROC curve is 0.75). Conclusion: Eschar and peripheral lymphadenopathy were two valuable clinical symptoms for the diagnosis of scrub typhus and distinguishing 2 groups of diseases. Respiratory distress, increase in AST ≥ 200 UI/l and level of PCT were used as major prognostic factors in patients with Rickettsiaceae.