Streptococcus suis infection, an emerging zoonosis, is an increasing public health problem across South East Asia and the most common cause of acute bacterial meningitis in adults in Vietnam. Little ...is known of the risk factors underlying the disease.
A case-control study with appropriate hospital and matched community controls for each patient was conducted between May 2006 and June 2009. Potential risk factors were assessed using a standardized questionnaire and investigation of throat and rectal S. suis carriage in cases, controls and their pigs, using real-time PCR and culture of swab samples. We recruited 101 cases of S. suis meningitis, 303 hospital controls and 300 community controls. By multivariate analysis, risk factors identified for S. suis infection as compared to either control group included eating "high risk" dishes, including such dishes as undercooked pig blood and pig intestine (OR(1) = 2.22; 95%CI = 1.15-4.28 and OR(2) = 4.44; 95%CI = 2.15-9.15), occupations related to pigs (OR(1) = 3.84; 95%CI = 1.32-11.11 and OR(2) = 5.52; 95%CI = 1.49-20.39), and exposures to pigs or pork in the presence of skin injuries (OR(1) = 7.48; 95%CI = 1.97-28.44 and OR(2) = 15.96; 95%CI = 2.97-85.72). S. suis specific DNA was detected in rectal and throat swabs of 6 patients and was cultured from 2 rectal samples, but was not detected in such samples of 1522 healthy individuals or patients without S. suis infection.
This case control study, the largest prospective epidemiological assessment of this disease, has identified the most important risk factors associated with S. suis bacterial meningitis to be eating 'high risk' dishes popular in parts of Asia, occupational exposure to pigs and pig products, and preparation of pork in the presence of skin lesions. These risk factors can be addressed in public health campaigns aimed at preventing S. suis infection.
The pathogenesis of dengue in infants is poorly understood. We postulated that dengue severity in infants would be positively associated with markers of viral burden and that maternally derived, ...neutralizing anti-dengue antibody would have decayed before the age at which infants with dengue presented to the hospital. In 75 Vietnamese infants with primary dengue, we found significant heterogeneity in viremia and NS1 antigenemia at hospital presentation, and these factors were independent of disease grade or continuous measures of disease severity. Neutralizing antibody titers, predicted in each infant at the time of their illness, suggested that the majority of infants (65%) experienced dengue hemorrhagic fever when the maternally derived neutralizing antibody titer had declined to <1:20. Collectively, these data have important implications for dengue vaccine research because they suggest that viral burden may not solely explain severe dengue in infants and that neutralizing antibody is a reasonable but not absolute marker of protective immunity in infants.
Background. Trypanosoma is a genus of unicellular parasitic flagellate protozoa. Trypanosoma brucei species and Trypanosoma cruzi are the major agents of human trypanosomiasis; other Trypanosoma ...species can cause human disease, but are rare. In March 2015, a 38-year-old woman presented to a healthcare facility in southern Vietnam with fever, headache, and arthralgia. Microscopic examination of blood revealed infection with Trypanosoma. Methods. Microscopic observation, polymerase chain reaction (PCR) amplification of blood samples, and serological testing were performed to identify the infecting species. The patient's blood was screened for the trypanocidal protein apolipoprotein L1 (APOL1), and a field investigation was performed to identify the zoonotic source. Results. PCR amplification and serological testing identified the infecting species as Trypanosoma evansi. Despite relapsing 6 weeks after completing amphotericin B therapy, the patient made a complete recovery after 5 weeks of suramin. The patient was found to have 2 wild-type APOL1 alleles and a normal serum APOL1 concentration. After responsive animal sampling in the presumed location of exposure, cattle and/or buffalo were determined to be the most likely source of the infection, with 14 of 30 (47%) animal blood samples testing PCR positive for T. evansi. Conclusions. We report the first laboratory-confirmed case of T. evansi in a previously healthy individual without APOL1 deficiency, potentially contracted via a wound while butchering raw beef, and successfully treated with suramin. A linked epidemiological investigation revealed widespread and previously unidentified burden of T. evansi in local cattle, highlighting the need for surveillance of this infection in animals and the possibility of further human cases.
The pathogenesis of severe dengue is not well understood. Maternally derived subneutralizing levels of dengue virus-reactive IgG are postulated to be a critical risk factor for severe dengue during ...infancy. In this study, we found that, in healthy Vietnamese infants, there was a strong temporal association between the Fc-dependent, dengue virus infection-enhancing activity of neat plasma and the age-related epidemiology of severe dengue. We then postulated that disease severity in infants with primary infections would be associated with a robust immune response, possibly as a consequence of higher viral burdens in vivo. Accordingly, in infants hospitalized with acute dengue, the activation phenotype of peripheral-blood NK cells and CD8+ and CD4+ T cells correlated with overall disease severity, but HLA-A*1101-restricted NS3133–142-specific CD8+ T cells were not measurable until early convalescence. Plasma levels of cytokines/chemokines were generally higher in infants with dengue shock syndrome. Collectively, these data support a model of dengue pathogenesis in infants whereby antibody-dependent enhancement of infection explains the age-related case epidemiology and could account for antigen-driven immune activation and its association with disease severity. These results also highlight potential risks in the use of live attenuated dengue vaccines in infants in countries where dengue is endemic.
We performed a prospective multicenter study to address the lack of data on the etiology, clinical and demographic features of hospitalized pediatric diarrhea in Ho Chi Minh City (HCMC), Vietnam. ...Over 2,000 (1,419 symptomatic and 609 non-diarrheal control) children were enrolled in three hospitals over a 1-year period in 2009-2010. Aiming to detect a panel of pathogens, we identified a known diarrheal pathogen in stool samples from 1,067/1,419 (75.2%) children with diarrhea and from 81/609 (13.3%) children without diarrhea. Rotavirus predominated in the symptomatic children (664/1,419; 46.8%), followed by norovirus (293/1,419; 20.6%). The bacterial pathogens Salmonella, Campylobacter, and Shigella were cumulatively isolated from 204/1,419 (14.4%) diarrheal children and exhibited extensive antimicrobial resistance, most notably to fluoroquinolones and third-generation cephalosporins. We suggest renewed efforts in generation and implementation of policies to control the sale and prescription of antimicrobials to curb bacterial resistance and advise consideration of a subsidized rotavirus vaccination policy to limit the morbidity due to diarrheal disease in Vietnam.
Acute Hepatopancreatic Necrosis Disease (AHPND) is a globally serious threat, especially for Vietnam shrimp culture. This disease is caused by toxin-carrying bacteria Vibrio parahaemolyticus which ...plasmid encodes binary toxins ToxA and ToxB. The disease has a mortality rate by up to 100% after 3–5 days post infection and fast spread among shrimp culturing regions. In 2017, a mutant of this disease named mutant-AHPND was recorded with a 1053 bp transposon inserted into toxA gene, toxB gene was not affected but the mortality rate was still up to 50% and the disease still spread quickly. There is no PCR test which can simultaneously detect both the normal and mutant plasmids of this disease commercially available. In this study, we developed a PCR test with single primer pairs which can specifically and simultaneously detect both types of the disease in shrimp. The PCR technique is established with a sensitivity of 2.5 pg per 20 μl reaction for plasmid solution and is four-times higher than that of the AP3 PCR kit which is commercially used in detection of AHPND disease in shrimp. Whereas the specificity of the method analyzed using two Vp-AHPND strains, one mutant Vp-AHPND strain, thirteen non-AHPND Vibrio species and White spot syndrome virus (WSSV) revealed that the method does not give unspecific reaction with non-AHPND bacteria and WSSV. The established PCR reaction is the core step in developing a PCR kit that helps detect both types of disease-causing plasmid in shrimp. With optimized parameters, this PCR kit can also be a cost-effective and rapid tool which can be used by shrimp cultivators and organizations in disease detection for epidemic monitoring.
•A novel monoplex PCR method for simultaneously detecting AHPND and mutant-AHPND in shrimp was established.•The monoplex PCR can detect both normal or mutant toxA and toxB genes with one single pair of primers.•Limit of detection of the monoplex PCR is four-times higher than that of commercially available kit.•The monoplex PCR method has successfully been validated on 64 field samples.
Responses by peripheral blood leukocytes may contribute to the pathogenesis of dengue hemorrhagic fever (DHF). We used DNA microarrays to reveal transcriptional patterns in the blood of 14 adults ...with DHF. Acute DHF was defined by an abundance of transcripts from cell cycle— and endoplasmic reticulum (ER)—related genes, suggesting a proliferative response accompanied by ER stress. Transcript-abundance levels for immunoresponse-associated genes, including cell surface markers, immunoglobulin, and innate response elements, were also elevated. Twenty-four genes were identified for which transcript abundance distinguished patients with dengue shock syndrome (DSS) from those without DSS. All the gene transcripts associated with DSS, many of which are induced by type I interferons, were less abundant in patients with DSS than in those without DSS. To our knowledge, these data provide the first snapshot of gene-expression patterns in peripheral blood during acute dengue and suggest that DSS is associated with attenuation of selected aspects of the innate host response.
Hand, foot and mouth disease (HFMD) is a major public health issue in Asia and has global pandemic potential. Coxsackievirus A6 (CV-A6) was detected in 514/2,230 (23%) of HFMD patients admitted to 3 ...major hospitals in southern Vietnam during 2011-2015. Of these patients, 93 (18%) had severe HFMD. Phylogenetic analysis of 98 genome sequences revealed they belonged to cluster A and had been circulating in Vietnam for 2 years before emergence. CV-A6 movement among localities within Vietnam occurred frequently, whereas viral movement across international borders appeared rare. Skyline plots identified fluctuations in the relative genetic diversity of CV-A6 corresponding to large CV-A6-associated HFMD outbreaks worldwide. These data show that CV-A6 is an emerging pathogen and emphasize the necessity of active surveillance and understanding the mechanisms that shape the pathogen evolution and emergence, which is essential for development and implementation of intervention strategies.
Since January 2018, over 53,000 hospitalisations and six deaths due to hand, foot and mouth disease (HFMD) have occurred across Vietnam with most cases from September onward. In a large tertiary ...referral hospital, Ho Chi Minh City, enterovirus A71 subgenogroup C4 was predominant, while B5 was only sporadically detected. The re-emergence of C4 after causing a severe HFMD outbreak with > 200 deaths in 2011-12 among susceptible young children raises concern of another impending severe outbreak.
The global COVID‐19 pandemic has been associated with high rates of severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) transmission, morbidity and mortality in the general population. ...Evidence‐based guidance on caring for babies born to mothers with COVID‐19 is needed. There is currently insufficient evidence to suggest vertical transmission between mothers and their newborn infants. However, transmission can happen after birth from mothers or other carers. Based on the currently available data, prolonged skin‐to‐skin contact and early and exclusive breastfeeding remain the best strategies to reduce the risks of morbidity and mortality for both the mother with COVID‐19 and her baby.
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