Publications

The biochemical characteristics of 213 isolates of Burkholderia pseudomallei from patients with melioidosis and 140 isolates from the soil in central and northeastern Thailand were compared. Whereas the biochemical profiles of all the clinical isolates were similar, all soil isolates from the central area and 25% of isolates from northeastern Thailand comprised a different phenotype. This was characterised by the ability to assimilate L-arabinose (100%), adonitol (100%), 5-keto-gluconate (90%) and D-xylose (84%), but failure to assimilate dulcitol (0%), erythritol (0%) and trehalose (10%). Compared with clinical isolates, these organisms had similar antibiotic susceptibility profiles and were also recognised by a specific polyclonal antibody against B. pseudomallei. As melioidosis is rare in central Thailand, but common in the northeast, this raises the possibility that this biochemical phenotype may be less virulent, or may even represent a different species.

No epidemiological typing system to differentiate among Pseudomonas pseudomallei isolates has been available. Ribotype analysis was developed and used to examine 74 clinical and 10 environmental isolates of P. pseudomallei from Thailand. Six P. pseudomallei ribotypes were identified from restriction fragment polymorphisms of EcoRI chromosomal digests. The predominant ribotype, A, was found in 59 of the isolates examined. By using patterns from hybridizations with SalI, HindIII, and PstI restriction digests, isolates of ribotype A were subdivided into a further five subtypes, giving a total of 10 differentiable P. pseudomallei types. In 23 of 34 melioidosis patients studied, multiple P. pseudomallei isolates were present. In all but one of these patients, a single ribotype of the organism was present. Isolation of two different ribotypes of P. pseudomallei from one patient, one each in sputum and urine, suggests that superinfection may have occurred. The ribotype was shown to be conserved during the course of antibiotic treatments in seven patients studied, although the antibiotic sensitivity patterns in the isolates from these patients varied. The prevalence of subtype A1 in clinical and environmental specimens suggests that this strain may be predominant in this geographical location. These results demonstrate the usefulness of the ribotyping method for epidemiological studies of P. pseudomallei.

Objective: To evaluate the efficacy and safety of liberal fluid resuscitation of adults with severe malaria. Design, Setting, Patients, and Methods: Twenty-eight Bangladeshi and Indian adults with severe falciparum malaria received crystalloid resuscitation guided by transpulmonary thermodilution (PiCCO) in an intensive care setting. Systemic hemodynamics, microvascular indices and measures of acidosis, renal function, and pulmonary edema were followed prospectively. Results: All patients were hypovolemic (global end-diastolic volume index < 680 mL/m2) on enrollment. Patients received a median (range) 3230 mL (390–7300) of isotonic saline in the first 6 hours and 5450 mL (710–13,720) in the first 24 hours. With resuscitation, acid-base status deteriorated in 19 of 28 (68%), and there was no significant improvement in renal function. Extravascular lung water increased in 17 of 22 liberally resuscitated patients (77%); eight of these patients developed pulmonary edema, five of whom died. All other patients survived. All patients with pulmonary edema during the study were hypovolemic or euvolemic at the time pulmonary edema developed. Plasma lactate was lower in hypovolemic patients before (rs = 0.38; p = 0.05) and after (rs = 0.49; p = 0.01) resuscitation but was the strongest predictor of mortality before (chi-square = 9.9; p = 0.002) and after resuscitation (chi-square = 11.1; p < 0.001) and correlated with the degree of visualized microvascular sequestration of parasitized erythrocytes at both time points (rs = 0.55; p = 0.003 and rs = 0.43; p = 0.03, respectively). Persisting sequestration was evident in 7 of 15 patients (47%) 48 hours after enrollment. Conclusions: Lactic acidosis—the strongest prognostic indicator in adults with severe falciparum malaria—results from sequestration of parasitized erythrocytes in the microcirculation, not from hypovolemia. Liberal fluid resuscitation has little effect on this sequestration and does not improve acid-base status or renal function. Pulmonary edema—secondary to increased pulmonary vascular permeability—is common, unpredictable, and exacerbated by fluid loading. Liberal fluid replacement of adults with severe malaria should be avoided.

The Plasmodium vivax that was once prevalent in temperate climatic zones typically had an interval between primary infection and first relapse of 7-10 months, whereas in tropical areas P.vivax infections relapse frequently at intervals of 3-6 weeks. Defining the epidemiology of these two phenotypes from temporal patterns of illness in endemic areas is difficult or impossible, particularly if they overlap.A prospective open label comparison of chloroquine (CQ) alone versus CQ plus unobserved primaquine for either 5 days or 14 days was conducted in patients presenting with acute vivax malaria in Kolkata. Patients were followed for 15 months and primary and recurrent infections were genotyped using three polymorphic antigen and up to 8 microsatellite markers.151 patients were enrolled of whom 47 (31%) had subsequent recurrent infections. Recurrence proportions were similar in the three treatment groups. Parasite genotyping revealed discrete temporal patterns of recurrence allowing differentiation of probable relapse from newly acquired infections. This suggested that 32 of the 47 recurrences were probable relapses of which 22 (69%) were genetically homologous. The majority (81%) of probable relapses occurred within three months (16 homologous, 10 heterologous) and six genetically homologous relapses (19%) were of the long latency (8-10 month interval) phenotype.With long follow-up to assess temporal patterns of vivax malaria recurrence, genotyping of P.vivax can be used to assess relapse rates. A 14 day unobserved course of primaquine did not prevent relapse. Genotyping indicates that long latency P.vivax is prevalent in West Bengal, and that the first relapses after long latent periods are genetically homologous.Controlled-Trials.com ISRCTN14027467.

Summary Objective To use electron microscopy to examine the role of parasitized red blood cell (PRBC) sequestration in the pathogenesis of acute renal failure in severe falciparum malaria. Methods Ultrastructural pathological examination of renal tissues from Southeast Asian adults ( n = 63) who died from severe falciparum malaria. Qualitative and quantitative determination of the major pathological features of disease, including PRBC and leukocyte sequestration. Clinico‐pathological correlation with the pre‐mortem clinical picture and peripheral parasite count. Results There was a high incidence of malaria‐associated renal failure in this population (&gt; 40%) and a correlation between this incidence, severe malarial anaemia and shock. Pathological features included PRBC sequestration in glomerular and tubulo‐interstitial vessels, acute tubular damage and mild glomerular hypercellularity resulting from the accumulation of host monocytes within glomerular capillaries. No evidence for an immune complex mediated glomerulonephritis was found. There was a correlation between parasite sequestration in the kidney and pre‐mortem renal failure, although overall levels of sequestration were relatively low. Levels of sequestration (Knob+ PRBC) were significantly higher in malaria‐associated renal failure than in fatal cases without renal failure ( P = 0.005). Conclusion Malaria‐associated renal failure is a common and serious complication of severe Plasmodium falciparum malaria in this population, associated with acute tubular injury rather than glomerulonephritis, and linked to localization of host monocytes in the kidney as well as sequestration of PRBCs.

<ns4:p><ns4:bold>Background: </ns4:bold>The COPCOV study (chloroquine/ hydroxychloroquine prevention of coronavirus disease), which started recruitment in April 2020, is a multi-country double-blind, randomised, placebo-controlled trial which is being conducted in healthcare facilities involved in COVID-19 case management. Participants are staff employed in facilities managing people with proven or suspected COVID-19. As part of the study, we conducted a series of engagement sessions. The aims were to assess the feasibility of the study, to identify context-specific ethical issues, to understand possible concerns, to fine tune research procedures and to refine the COPCOV information materials.</ns4:p><ns4:p> <ns4:bold>Methods:</ns4:bold> The COPCOV study was approved by relevant institutional review boards. The sessions described in this paper were part of the study. We conducted a series of engagement sessions, each involving a short presentation of the study, a section where attendees were asked to express their willingness to participate in such a study, which information they would need to change their view and an open Q&amp;A section. Answers were transcribed and coded into themes by two independent investigators. Themes were derived from the data. They complemented other site-specific engagement, communication, and public relation activities such as press releases and websites.</ns4:p><ns4:p> <ns4:bold>Results and conclusions:</ns4:bold> From 16 <ns4:sup>th</ns4:sup> March 2020 to 20 <ns4:sup>th</ns4:sup> January 2021, 13 engagement sessions were conducted in Thailand, Laos, Vietnam, Nepal and the UK involving 222 attendees in total. Issues raised revolved around the social value and study rationale; safety of trial medications and risk-benefit balance; study design and commitments. These sessions helped us identify concerns people had, which helped us refine information materials as well as complement site feasibility assessments. Our experience strongly supports the use of participatory practices prior to conducting clinical trials.</ns4:p>

To establish a means of efficiently transducing human glial progenitor cells (hGPCs) in vivo with therapeutic transgenes, we targeted PDGFRA-driven Cre-recombinase expressing hGPCs in human glial chimeric mice with a library of capsid-modified, recombination-reported adeno-associated viruses (AAVs). PCR screening for gliotropic viral capsid sequences, filtered against visceral organs, identified a set of AAV5-based vectors that preferentially infected human GPCs and/or their derived astrocytes and oligodendrocytes in vivo, with minimal systemic infection. To maximize the intracerebral distribution of these viruses while minimizing their dosing and extracerebral spread, we paired their intracisternal delivery with systemic hypertonicity. This method exploited intracerebral glymphatic flow to bypass the blood-brain barrier, delivering AAV directly into the brain parenchyma. Glymphatic delivery of capsid-modified AAV5s, evolved on human GPCs in vivo, thus enables efficient, brain-wide transgene delivery to human glia and their progenitors in the adult brain, with minimal off-target transduction.

Journal Article Artesunate versus artemether in combination with mefloquine for the treatment of multidrug-resistant falciparum malaria Get access R.N. Price, R.N. Price 1Shoklo Malaria Research Unit, P.O. Box 46, Mae Sod 63110, Tak Province, Thailand2Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand3Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, John Radcliffe Hospital, Oxford, UK Search for other works by this author on: Oxford Academic PubMed Google Scholar F. Nosten, F. Nosten 1Shoklo Malaria Research Unit, P.O. Box 46, Mae Sod 63110, Tak Province, Thailand2Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand3Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, John Radcliffe Hospital, Oxford, UK Search for other works by this author on: Oxford Academic PubMed Google Scholar C. Luxemburger, C. Luxemburger 1Shoklo Malaria Research Unit, P.O. Box 46, Mae Sod 63110, Tak Province, Thailand2Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand Search for other works by this author on: Oxford Academic PubMed Google Scholar Am Kham, Am Kham 1Shoklo Malaria Research Unit, P.O. Box 46, Mae Sod 63110, Tak Province, Thailand Search for other works by this author on: Oxford Academic PubMed Google Scholar A. Brockman, A. Brockman 1Shoklo Malaria Research Unit, P.O. Box 46, Mae Sod 63110, Tak Province, Thailand2Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand Search for other works by this author on: Oxford Academic PubMed Google Scholar T. Chongsuphajaisiddhi, T. Chongsuphajaisiddhi 2Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand Search for other works by this author on: Oxford Academic PubMed Google Scholar N.J. White N.J. White ∗ 2Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand3Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, John Radcliffe Hospital, Oxford, UK ∗Address for correspondence: Dr N. J. White, Faculty of Tropical Medicine, Mahidol University, 420/6 Rajvithi Road, Bangkok 10400, Thailand. Search for other works by this author on: Oxford Academic PubMed Google Scholar Transactions of The Royal Society of Tropical Medicine and Hygiene, Volume 89, Issue 5, September-October 1995, Pages 523–527, https://doi.org/10.1016/0035-9203(95)90094-2 Published: 01 September 1995 Article history Received: 05 April 1995 Revision received: 11 May 1995 Accepted: 11 May 1995 Published: 01 September 1995

Additional file 2. Summary of all genotypes available.

Summary Several years ago the Walter Reed Army Institute of Research (WRAIR) initiated an independent analysis of the candidate malaria blood stage vaccine SPf66. WRAIR contracted for the synthesis and formulation of SPf66 in United States Food and Drug Administration (FDA) inspected laboratories within the U.S., and in 1992, filed an Investigational New Drug (IND) application with the FDA. Preclinical studies indicated that the vaccine could be synthesized to meet its release specifications, and when adjuvanted with alum, was essentially equivalent to Colombian produced SPf66 in regards to immunogenicity in preclinical studies of rodents and primates, and in human volunteers in Phase I studies. The goal of these efforts was ultimately to conduct a Phase IIb field trial to determine the safety and efficacy of SPf66 produced under current Good Manufacturing Practices (cGMP). Such a trial is currently underway in a malaria endemic refugee camp along the Thai–Burmese border. Here we briefly describe the study and present the formal analytic plan that was submitted to regulatory authorities in the United States for analysis of the study results. We believe such independent confirmatory studies are an essential part of the vaccine development process and are required to provide important data regarding the safety and efficacy of candidate vaccines in diverse geographical regions, and as a means to assess their role in the context of broader malaria control programmes.

Understanding the human immune response to Plasmodium falciparum gametocytes and its association with gametocytemia is essential for understanding the transmission of malaria as well as progressing transmission blocking vaccine candidates. In a multi-national clinical efficacy trial of artemisinin therapies (13 sites of varying transmission over South-East Asia and Africa), we measured Immunoglobulin G (IgG) responses to recombinant P. falciparum gametocyte antigens expressed on the gametocyte plasma membrane and leading transmission blocking vaccine candidates Pfs230 (Pfs230c and Pfs230D1M) and Pfs48/45 at enrolment in 1,114 participants with clinical falciparum malaria. Mixed effects linear and logistic regression were used to determine the association between gametocyte measures (gametocytemia and gametocyte density) and antibody outcomes at enrolment. Microscopy detectable gametocytemia was observed in 11% (127/1,114) of participants at enrolment, and an additional 9% (95/1,114) over the follow-up period (up to day 42) (total 20% of participants [222/1,114]). IgG levels in response to Pfs230c, Pfs48/45 and Pfs230D1M varied across study sites at enrolment (p < 0.001), as did IgG seroprevalence for anti-Pfs230c and D1M IgG (p < 0.001), but not for anti-Pfs48/45 IgG (p = 0.159). In adjusted analyses, microscopy detectable gametocytemia at enrolment was associated with an increase in the odds of IgG seropositivity to the three gametocyte antigens (Pfs230c OR [95% CI], p: 1.70 [1.10, 2.62], 0.017; Pfs48/45: 1.45 [0.85, 2.46], 0.174; Pfs230D1M: 1.70 [1.03, 2.80], 0.037), as was higher gametocyte density at enrolment (per two-fold change in gametocyte density Pfs230c OR [95% CI], p: 1.09 [1.02, 1.17], 0.008; Pfs48/45: 1.05 [0.98, 1.13], 0.185; Pfs230D1M: 1.07 [0.99, 1.14], 0.071). Pfs230 and Pfs48/45 antibodies are naturally immunogenic targets associated with patent gametocytemia and increasing gametocyte density across multiple malaria endemic settings, including regions with emerging artemisinin-resistant P. falciparum.

No abstract is provided for this article.

A growing literature now documents the presence of fine‐scale genetic structure in wild vertebrate populations. Breeding population size, levels of dispersal and polygyny — all hypothesized to affect population genetic structure — are known to be influenced by ecological conditions experienced by populations. However the possibility of temporal or spatial variation in fine‐scale genetic structure as a result of ecological change is rarely considered or explored. Here we investigate temporal variation in fine‐scale genetic structure in a red deer population on the Isle or Rum, Scotland. We document extremely fine‐scale spatial genetic structure (&lt; 100 m) amongst females but not males across a 24‐year study period during which resource competition has intensified and the population has reached habitat carrying capacity. Based on census data, adult deer were allocated to one of three subpopulations in each year of the study. Global F ST estimates for females generated using these subpopulations decreased over the study period, indicating a rapid decline in fine‐scale genetic structure of the population. Global F ST estimates for males were not different from zero across the study period. Using census and genetic data, we illustrate that, as a consequence of a release from culling early in the study period, the number of breeding females has increased while levels of polygyny have decreased in this population. We found little evidence for increasing dispersal between subpopulations over time in either sex. We argue that both increasing female population size and decreasing polygyny could explain the decline in female population genetic structure.