Leptospirosis and melioidosis coinfection presenting as acute respiratory distress syndrome and osteomyelitis: Case report and systematic review.

INTRODUCTION: Leptospirosis and melioidosis are common in tropical and temperate climates and can be acquired by exposure to contaminated water and soil. However, concomitant leptospirosis and melioidosis infection is rarely described in the literature. We report a case of leptospirosis-melioidosis coinfection and systematically review the literature. CASE PRESENTATION: A 42-year-old male presented with fever associated with chills and rigor, dull aching pain in the right thigh, myalgia, progressive breathlessness, and dry cough for 10 days. At presentation, he was tachypneic and had tachycardia, and oxygen saturation was 46% in room air. Chest radiography and computed tomography scan showed interstitial involvement. Magnetic resonance imaging for thigh pain revealed right femur osteomyelitis. Leptospira serology was positive, and blood culture grew Burkholderia pseudomallei, confirming the diagnosis of melioidosis. Thus, a diagnosis of presumptive leptospirosis based on modified Faine's criteria and systemic melioidosis was made. He received doxycycline and intravenous meropenem and improved. RESULTS: We performed a systematic review to understand the spectrum of leptospirosis-melioidosis coinfection. We identified only nine cases of coinfection described in literature. Only one patient had septic arthritis, and our case is the only one presenting with osteomyelitis. Serology diagnosed leptospirosis, whereas melioidosis was confirmed by blood culture in most patients. The majority of coinfected patients developed some complications, and six died. CONCLUSIONS: Leptospirosis-melioidosis coinfection is rarely reported in the literature. Physicians should maintain a high index suspicion of leptospirosis-melioidosis coinfection in patients presenting with acute febrile illness following exposure to soil or freshwater, particularly in tropical and endemic regions.

A molecular epidemiological analysis of Burkholderia pseudomallei in southern Thailand.

Melioidosis, a severe bacterial illness caused by Burkholderia pseudomallei, is prevalent in most parts of Thailand, including its southern region situated within the Malay Peninsula. Despite a lower reported incidence rate of melioidosis in the South compared to the Northeast, the mortality rate remains persistently high. This study aimed to better understand the epidemiology and investigate the presence of B. pseudomallei in the natural environment of southern Thailand. Using multi-locus sequence typing (MLST), we characterized B. pseudomallei isolates derived from human cases and compared them with previously reported sequence types (STs) from the same region. A total of 263 clinical isolates retrieved from 156 melioidosis patients between 2014 and 2020 were analyzed, revealing 72 distinct STs, with 25 (35%) matching STs from Finkelstein's environmental isolates collected in southern Thailand during 1964-1967. Notably, strains bearing STs 288, 84, 54, 289, and 46 were frequently found among patients. Additionally, we observed strain diversity with multiple STs in 13 of 59 patients, indicating exposure to various B. pseudomallei genotypes in the environmental sources of the infection. Environmental surveys were conducted in Songkhla Province to detect B. pseudomallei in soil and water samples where local patients lived. Of the 2737 soil samples from 208 locations and 244 water samples from diverse sources, 52 (25%) soil sampling locations and 63 (26%) water sources were cultured positive for B. pseudomallei. Positive soil samples were predominantly found in animal farming area and non-agricultural zones like mountains and grasslands, while water samples were frequently positive in waterfalls, streams, and surface runoffs, with only 9% of rice paddies testing positive. Collectively, a significant proportion of recent melioidosis cases in Songkhla Province can be attributed to known B. pseudomallei STs persisting in the environment for at least the past six decades. Further characterization of B. pseudomallei isolates from recent environment surveys is warranted. These findings illuminate the contemporary landscape of B. pseudomallei infections and their environmental prevalence in southern Thailand, contributing to the regional threat assessment in Thailand and Southeast Asia.

The genetic diversity and evolution analysis of the Hainan melioidosis outbreak strains.

Melioidosis is a zoonotic disease, with its outbreaks being rare and indicative of an unusual concurrence of extreme climate and natural environmental factors. An outbreak of melioidosis cases emerged in Hainan following Typhoon "Dianmu" from October to December 2021, presenting an opportunity to identify the environmental sources of infection for these cases due to its nature as a well-defined point-source cluster. To investigate the relationship between the occurrence of these melioidosis cases and the environment, we extracted the entire genome of 25 clinical strains and conducted MLST typing, followed by whole genome sequencing and analysis of molecular genetic information for four ST46 genotypes from these strains. Phylogenetic and evolutionary relationships between Hainan sequence types (STs) and those found in other endemic regions were analyzed using IslandPath-DIMO, PHASTER, e-BURST, PHYLOViZ, and the maximum likelihood method. Notably, a total of 25 clinical strains were identified, encompassing 12 STs (ST46, ST1105, ST1991, ST30, ST1992, ST50, ST164, ST55, ST70, ST1993, ST1545, and ST58), with ST1991, ST1992, and ST1993 being newly discovered subtypes. PHYLOViZ clustering analysis divided the strains into two groups (A and B), both closely related to the Asian region. Phylogenetic tree analysis further revealed that most of the strains in this study were closely related to those found in Australia and Thailand. Analysis of patient information and visits to their residences suggested that contaminated water sources might be the primary source of infection during this outbreak. Our findings underscore that extreme weather events, such as typhoons, significantly increase the infection rate of B. pseudomallei, along with its genetic diversity, necessitating additional prevention strategies to control these B. pseudomallei infections.

Isolation and characterization of ssDNA aptamers against BipD antigen of Burkholderia pseudomallei.

BACKGROUND: Melioidosis is difficult to diagnose due to its wide range of clinical symptoms. The culture method is time-consuming and less sensitive, emphasizing the importance of rapid and accurate diagnostic tests for melioidosis. Burkholderia invasion protein D (BipD) of Burkholderia pseudomallei is a potential diagnostic biomarker. This study aimed to isolate and characterize single-stranded DNA aptamers that specifically target BipD. METHODS: The recombinant BipD protein was produced, followed by isolation of BipD-specific aptamers using Systematic Evolution of Ligands by EXponential enrichment. The binding affinity and specificity of the selected aptamers were evaluated using Enzyme-Linked Oligonucleotide Assay. RESULTS: The fifth SELEX cycle showed a notable enrichment of recombinant BipD protein-specific aptamers. Sequencing analysis identified two clusters with a total of seventeen distinct aptamers. AptBipD1, AptBipD13, and AptBipD50 were chosen based on their frequency. Among them, AptBipD1 exhibited the highest binding affinity with a Kd value of 1.0 µM for the recombinant BipD protein. Furthermore, AptBipD1 showed significant specificity for B. pseudomallei compared to other tested bacteria. CONCLUSION: AptBipD1 is a promising candidate for further development of reliable, affordable, and efficient point-of-care diagnostic tests for melioidosis.

Epidemiology and clinical spectrum of melioidosis: Analysis of cases from a tertiary care centre in southern Tamil Nadu.

Background We studied the clinical features and treatment outcome of patients with melioidosis in our hospital. Methods We did this retrospective observational chart review over a period of 7 years between December 2014 and February 2022. Results There were 59 cases and 23 deaths attributable to melioidosis over the study period. The age range was 5 to 74 years and 48 (81.3%) were men. The comorbid conditions included diabetes mellitus (68%), alcoholism (11.8%), pulmonary tuberculosis (6.7%) and chronic kidney disease (5%). Over three-fourths of patients (78%) presented during the rainy season (June to December) and were acute presentations (44 [75%]). The most common sites were liver and spleen, followed by the musculoskeletal system, skin, soft tissues, lungs and brain. Of the 21 (36%) patients with septic shock, 16 (76%) died. On the contrary, of 38 (64%) patients without septic shock, only 11% died. Of the 27 (47%) admitted to ICU, 11 (41%) died. In ICU, 18 (67%) were ventilated. Of the 23 (39%) deaths overall, median time from admission to death was 4 days. There were no relapses in the 42% patients followed up for 2-6 months. Conclusions The epidemiology of melioidosis is similar to other endemic areas with preponderance of men. There was a temporal association with the monsoon season and a higher number of acute cases. The differences included a higher proportion of deep visceral abscesses and musculo-skeletal involvement compared to lung involvement.

Predictors of mortality in culture-proven Burkholderia pseudomallei infections in a Singapore Tertiary Hospital.

Burkholderia pseudomallei is a pathogen expanding in geographic range. We performed a retrospective study analyzing the clinical, microbiologic features of culture-proven melioidosis, and predictors of mortality based on data from a Singapore tertiary hospital between 2006- 2016. We found ICU admission, bacteremia, and mechanical ventilation to be associated with mortality.

Analysis of fine-scale phylogeny of Burkholderia pseudomallei in relation to regional geography and drug susceptibility in Thailand.

Melioidosis caused by Burkholderia pseudomallei (Bp) is a public health threat. Genomic-epidemiology research on this deadly disease is scarce. We investigated whole-genome sequences of Bp isolates in relation to environmental source and drug susceptibility. In total, 563 Bp isolates were collected from 11 Northeast Thai provinces during the period 2004-2021. Patients (n = 530 isolates), infected animals (n = 8), and environmental sources (n = 25) provided samples. Phylogenetic analysis revealed genetic diversity among the Bp isolates, including numerous well-supported clusters of varying sizes. Through in-depth analysis of 38 monophyletic clades (MCs), we found eleven associated with province of origin (p-value < 0.001). Closely related clusters (CRCs) within MCs resembled MLST-identified "sequence types" (STs). We found 102 known and 52 novel STs. ST-70 was the most prevalent in this area (n = 78; 13.85%). Sample type (human/environmental) and sampling time intervals were not correlated with genetic distance among clonal Bp isolates. Some members of 12 CRCs had acquired resistance to co-trimoxazole and one against amoxicillin-clavulanic acid. Within Northeast Thailand, there is an association between Bp genotype and geographical origin.

Point mutation P174L of the penA gene endowing ceftazidime resistance to Burkholderia pseudomallei in China.

In a clinical isolate of Burkholderia pseudomallei from Hainan, the association between the emergence of ceftazidime resistance and a novel PenA P174L allele was identified for the first time, providing an understanding of one mechanism by which ceftazidime resistance arises in B. pseudomallei.

Bone and joint infections due to melioidosis; diagnostic and management strategies to optimise outcomes.

BACKGROUND: Melioidosis, a life-threatening infection caused by the gram negative bacterium Burkholderia pseudomallei, can involve almost any organ. Bone and joint infections (BJI) are a recognised, but incompletely defined, manifestation of melioidosis that are associated with significant morbidity and mortality in resource-limited settings. METHODOLOGY/PRINCIPAL FINDINGS: We identified all individuals with BJI due to B. pseudomallei managed at Cairns Hospital in tropical Australia between January 1998 and June 2023. The patients' demographics, their clinical findings and their treatment were correlated with their subsequent course. Of 477 culture-confirmed cases of melioidosis managed at the hospital during the study period, 39 (8%) had confirmed BJI; predisposing risk factors for melioidosis were present in 37/39 (95%). However, in multivariable analysis only diabetes mellitus was independently associated with the presence of BJI (odds ratio (95% confidence interval): 4.04 (1.81-9.00), p = 0.001). BJI was frequently only one component of multi-organ involvement: 29/39 (74%) had infection involving other organs and bacteraemia was present in 31/39 (79%). Of the 39 individuals with BJI, 14 (36%) had osteomyelitis, 8 (20%) had septic arthritis and 17 (44%) had both osteomyelitis and septic arthritis; in 32/39 (83%) the lower limb was involved. Surgery was performed in 30/39 (77%). Readmission after the initial hospitalisation was necessary in 11/39 (28%), 5/39 (13%) had disease recrudescence and 3/39 (8%) had relapse; 4/39 (10%) developed pathological fractures. ICU admission was necessary in 11/39 (28%) but all 11 of these patients survived. Only 1/39 (3%) died, 138 days after admission, due to his significant underlying comorbidity. CONCLUSIONS: The case-fatality rate from melioidosis BJI in Australia's well-resourced health system is very low. However, recrudescence, relapse and orthopaedic complications are relatively common and emphasise the importance of collaborative multidisciplinary care that includes early surgical review, aggressive source control, prolonged antibiotic therapy, and thorough, extended follow-up.

Genetic diversity, determinants, and dissemination of Burkholderia pseudomallei lineages implicated in melioidosis in Northeast Thailand.

Melioidosis is an often-fatal neglected tropical disease caused by an environmental bacterium Burkholderia pseudomallei. However, our understanding of the disease-causing bacterial lineages, their dissemination, and adaptive mechanisms remains limited. To address this, we conduct a comprehensive genomic analysis of 1,391 B. pseudomallei isolates collected from nine hospitals in northeast Thailand between 2015 and 2018, and contemporaneous isolates from neighbouring countries, representing the most densely sampled collection to date. Our study identifies three dominant lineages, each with unique gene sets potentially enhancing bacterial fitness in the environment. We find that recombination drives lineage-specific gene flow. Transcriptome analyses of representative clinical isolates from each dominant lineage reveal increased expression of lineage-specific genes under environmental conditions in two out of three lineages. This underscores the potential importance of environmental persistence for these dominant lineages. The study also highlights the influence of environmental factors such as terrain slope, altitude, and river direction on the geographical dispersal of B. pseudomallei. Collectively, our findings suggest that environmental persistence may play a role in facilitating the spread of B. pseudomallei, and as a prerequisite for exposure and infection, thereby providing useful insights for informing melioidosis prevention and control strategies.

Dysfunctional host cellular immune responses are associated with mortality in melioidosis.

Melioidosis is a tropical infection caused by the intracellular pathogen Burkholderia pseudomallei, an underreported and emerging global threat. As melioidosis-associated mortality is frequently high despite antibiotics, novel management strategies are critically needed. Therefore, we sought to determine whether functional changes in the host innate and adaptive immune responses are induced during acute melioidosis and are associated with outcome. Using a unique whole blood stimulation assay developed for use in resource-limited settings, we examined induced cellular functional and phenotypic changes in a cohort of patients with bacteremic melioidosis prospectively enrolled within 24 h of positive blood culture and followed for 28 days. Compared to healthy controls, melioidosis survivors generated an IL-17 response mediated by Th17 cells and terminally-differentiated effector memory CD8+ T cells (P < .05, both), persisting to 28 days after enrolment. Furthermore, melioidosis survivors developed polyfunctional cytokine production in CD8+ T cells (P < .01). Conversely, a reduction in CCR6+ CD4+ T cells was associated with higher mortality, even after adjustments for severity of illness (P = 0.004). Acute melioidosis was also associated with a profound acute impairment in monocyte function as stimulated cytokine responses were reduced in classical, intermediate and non-classical monocytes. Impaired monocyte cytokine function improved by 28-days after enrolment. These data suggest that IL-17 mediated cellular responses may be contributors to host defense during acute melioidosis, and that innate immune function may be impaired. These insights could provide novel targets for the development of therapies and vaccine targets in this frequently lethal disease.

Differentiation in pyroptosis induction by Burkholderia pseudomallei and Burkholderia thailandensis in primary human monocytes, a possible cause of sepsis in acute melioidosis patients.

Melioidosis caused by Burkholderia pseudomallei is an infectious disease with a high mortality rate. In acute melioidosis, sepsis is a major cause of death among patients. Once the bacterium enters the bloodstream, immune system dysregulation ensues, leading to cytokine storms. In contrast to B. pseudomallei, a closely related but non-virulent strain B. thailandensis has rarely been reported to cause cytokine storms or death in patients. However, the mechanisms in which the virulent B. pseudomallei causes sepsis are not fully elucidated. It is well-documented that monocytes play an essential role in cytokine production in the bloodstream. The present study, therefore, determined whether there is a difference in the innate immune response to B. pseudomallei and B. thailandensis during infection of primary human monocytes and THP-1 monocytic cells by investigating pyroptosis, an inflammatory death pathway known to play a pivotal role in sepsis. Our results showed that although both bacterial species exhibited a similar ability to invade human monocytes, only B. pseudomallei can significantly increase the release of cytosolic enzyme lactate dehydrogenase (LDH) as well as the increases in caspase-1 and gasdermin D activations in both cell types. The results were consistent with the significant increase in IL-1ß and IL-18 production, key cytokines involved in pyroptosis. Interestingly, there was no significant difference in other cytokine secretion, such as IL-1RA, IL-10, IL-12p70, IL-15, IL-8, and IL-23 in cells infected by both bacterial species. Furthermore, we also demonstrated that ROS production played a crucial role in controlling pyroptosis activation during B. pseudomallei infection in primary human monocytes. These findings suggested that pyroptosis induced by B. pseudomallei in the human monocytes may contribute to the pathogenesis of sepsis in acute melioidosis patients.

Tracking melioidosis in Iran: Utilizing abattoir-based surveillance as a One Health approach.

BACKGROUND: Burkholderia pseudomallei, an environmental saprophyte bacterium, causes melioidosis in humans and animals. It was first discovered in Iran between 1967 and 1976 in small ruminants, equines, environments and humans. No subsequent studies have been conducted to determine the existence and prevalence of this pathogen in the country. OBJECTIVES: The present study aims to monitor the presence of B. pseudomallei in the ruminant population of the Golestan province of Iran, which largely depends on pastures. The ruminants can serve as sentinels to indicate the presence of the bacteria in the environment and its potential impact on human health in the One Health triad. METHODS: Liver and lung abscesses from domestic sheep, cattle and goats in three industrial and three conventional slaughterhouses were sampled and analysed using 23S ribosomal DNA polymerase chain reaction (rDNA PCR) with primers CVMP 23-1 and CVP-23-2 for B. pseudomallei, Burkholderia cepacia and Burkholderia vietnamiensis, as well as B. pseudomallei-specific TTS1 real-time PCR, along with microbiological and biochemical assays. RESULTS: Out of the 97 animals sampled, only 14 (15%) tested positive for 23S rDNA PCR. However, the follow-up evaluation using TTS1 real-time PCR and microbiological and biochemical assays did not confirm the presence of B. pseudomallei in the samples. CONCLUSIONS: Although B. pseudomallei was not detected in the current survey, conducting abattoir-based surveillance of ruminants is a cost-effective One Health approach to monitor pathogenic Burkholderia. Developing standards of clinical and laboratory good practices for Burkholderia infections is crucial for One Health surveillance.

Diabetes and Infectious Diseases with a Focus on Melioidosis.

Diabetes mellitus (DM) leads to impaired innate and adaptive immune responses. This renders individuals with DM highly susceptible to microbial infections such as COVID-19, tuberculosis and melioidosis. Melioidosis is a tropical disease caused by the bacterial pathogen Burkholderia pseudomallei, where diabetes is consistently reported as the most significant risk factor associated with the disease. Type-2 diabetes is observed in 39% of melioidosis patients where the risk of infection is 13-fold higher than non-diabetic individuals. B. pseudomallei is found in the environment and is an opportunistic pathogen in humans, often exhibiting severe clinical manifestations in immunocompromised patients. The pathophysiology of diabetes significantly affects the host immune responses that play a critical role in fighting the infection, such as leukocyte and neutrophil impairment, macrophage and monocyte inhibition and natural killer cell dysfunction. These defects result in delayed recruitment as well as activation of immune cells to target the invading B. pseudomallei. This provides an advantage for the pathogen to survive and adapt within the immunocompromised diabetic patients. Nevertheless, knowledge gaps on diabetes-infectious disease comorbidity, in particular, melioidosis-diabetes comorbidity, need to be filled to fully understand the dysfunctional host immune responses and adaptation of the pathogen under diabetic conditions to guide therapeutic options.

Case Report: Risk Factors Associated with Mortality in Adults with Burkholderia Pseudomallei Bacteremia: A Retrospective Case Series of Melioidosis in Cambodia.

In resource-scarce settings, melioidosis is associated with up to 80% mortality. Studies of melioidosis in Cambodia report primarily on pediatric populations with localized infection; however, literature describing Cambodian adults with severe melioidosis is lacking. We present a case series of 35 adults with sequence-confirmed Burkholderia pseudomallei bacteremia presenting to a provincial referral hospital in rural Cambodia. More than 90% of the patients had diabetes, an important risk factor for developing melioidosis. Inappropriate antimicrobial therapy was significantly associated with lower odds of survival. Improved diagnostic testing and greater access to first-line antibiotics for acute melioidosis treatment present potential targets for intervention to reduce mortality associated with this disease in resource-limited settings.

Unraveling the role of toxin-antitoxin systems in Burkholderia pseudomallei: exploring bacterial pathogenesis and interactions within the HigBA families.

Burkholderia pseudomallei (Bpm) is a Gram-negative intracellular pathogen that causes melioidosis in humans, a neglected, underreported, and lethal disease that can reach a fatal outcome in over 50% of the cases. It can produce both acute and chronic infections, the latter being particularly challenging to eliminate because of the intracellular life cycle of the bacteria and its ability to generate a "persister" dormant state. The molecular mechanism that allows the switch between growing and persister phenotypes is not well understood but it is hypothesized to be due at least in part to the participation of toxin-antitoxin (TA) systems. We have previously studied the link between one of those systems (defined as HigBA) with specific expression patterns associated with levofloxacin antibiotic exposure. Through in silico methods, we predicted the presence of another three pairs of genes encoding for additional putative HigBA systems. Therefore, our main goal was to establish which mechanisms are conserved as well as which pathways are specific among different Bpm TA systems from the same family. We hypothesize that the high prevalence, and sometimes even redundancy of these systems in the Bpm chromosomes indicates that they can interact with each other and not function as only individual systems, as it was traditionally thought, and might be playing an undefined role in Bpm lifecycle. Here, we show that both the toxin and the antitoxin of the different systems contribute to bacterial survival and that toxins from the same family can have a cumulative effect under environmental stressful conditions. IMPORTANCE: Toxin-antitoxin (TA) systems play a significant role in bacterial persistence, a phenomenon where bacterial cells enter a dormant or slow-growing state to survive adverse conditions such as nutrient deprivation, antibiotic exposure, or host immune responses. By studying TA systems in Burkholderia pseudomallei, we can gain insights into how this pathogen survives and persists in the host environment, contributing to its virulence and ability to cause melioidosis chronic infections.

Burkholderia pseudomallei BipD modulates host mitophagy to evade killing.

Mitophagy is critical for mitochondrial quality control and function to clear damaged mitochondria. Here, we found that Burkholderia pseudomallei maneuvered host mitophagy for its intracellular survival through the type III secretion system needle tip protein BipD. We identified BipD, interacting with BTB-containing proteins KLHL9 and KLHL13 by binding to the Back and Kelch domains, recruited NEDD8 family RING E3 ligase CUL3 in response to B. pseudomallei infection. Although evidently not involved in regulation of infectious diseases, KLHL9/KLHL13/CUL3 E3 ligase complex was essential for BipD-dependent ubiquitination of mitochondria in mouse macrophages. Mechanistically, we discovered the inner mitochondrial membrane IMMT via host ubiquitome profiling as a substrate of KLHL9/KLHL13/CUL3 complex. Notably, K63-linked ubiquitination of IMMT K211 was required for initiating host mitophagy, thereby reducing mitochondrial ROS production. Here, we show a unique mechanism used by bacterial pathogens that hijacks host mitophagy for their survival.

Diagnostic accuracy of automation and non-automation techniques for identifying Burkholderia pseudomallei: A systematic review and meta-analysis.

BACKGROUND: Burkholderia pseudomallei, a Gram-negative pathogen, causes melioidosis. Although various clinical laboratory identification methods exist, culture-based techniques lack comprehensive evaluation. Thus, this systematic review and meta-analysis aimed to assess the diagnostic accuracy of culture-based automation and non-automation methods. METHODS: Data were collected via PubMed/MEDLINE, EMBASE, and Scopus using specific search strategies. Selected studies underwent bias assessment using QUADAS-2. Sensitivity and specificity were computed, generating pooled estimates. Heterogeneity was assessed using I2 statistics. RESULTS: The review encompassed 20 studies with 2988 B. pseudomallei samples and 753 non-B. pseudomallei samples. Automation-based methods, particularly with updating databases, exhibited high pooled sensitivity (82.79%; 95% CI 64.44-95.85%) and specificity (99.94%; 95% CI 98.93-100.00%). Subgroup analysis highlighted superior sensitivity for updating-database automation (96.42%, 95% CI 90.01-99.87%) compared to non-updating (3.31%, 95% CI 0.00-10.28%), while specificity remained high at 99.94% (95% CI 98.93-100%). Non-automation methods displayed varying sensitivity and specificity. In-house latex agglutination demonstrated the highest sensitivity (100%; 95% CI 98.49-100%), followed by commercial latex agglutination (99.24%; 95% CI 96.64-100%). However, API 20E had the lowest sensitivity (19.42%; 95% CI 12.94-28.10%). Overall, non-automation tools showed sensitivity of 88.34% (95% CI 77.30-96.25%) and specificity of 90.76% (95% CI 78.45-98.57%). CONCLUSION: The study underscores automation's crucial role in accurately identifying B. pseudomallei, supporting evidence-based melioidosis management decisions. Automation technologies, especially those with updating databases, provide reliable and efficient identification.

Melioidosis and Activation from Latency: The "Time Bomb" Has Not Occurred.

Burkholderia pseudomallei, the causative agent of melioidosis has long been considered able to exist in a latent form. Seropositivity among U.S. soldiers returning from the Vietnam conflict led to melioidosis being dubbed "the Vietnamese time bomb." Cases assigned to "(re)activation from latency" over 30 years of the Darwin Prospective Melioidosis Study (DPMS) were reviewed and reassessed and additional cases from DPMS years 31-34 were added. Historical reports of melioidosis attributed to activation from latency were reviewed. Some earlier DPMS cases and most historical cases described as activation from latency more accurately reflect undiagnosed chronic melioidosis, often with relapsing-remitting courses, rather than truly latent, asymptomatic infection. Such protracted disease should now be diagnosable much earlier, provided melioidosis is considered and laboratory facilities are available. The longest plausible duration of asymptomatic latency remains 29 years. In conclusion, activation from latency is a rare event in melioidosis, accounting in our analysis for under 3% of DPMS cases, consistent with why the Vietnamese time bomb never eventuated.