Imported Malaria in Countries where Malaria Is Not Endemic: a Comparison of Semi-immune and Nonimmune Travelers.

The continuous increase in long-distance travel and recent large migratory movements have changed the epidemiological characteristics of imported malaria in countries where malaria is not endemic (here termed non-malaria-endemic countries). While malaria was primarily imported to nonendemic countries by returning travelers, the proportion of immigrants from malaria-endemic regions and travelers visiting friends and relatives (VFRs) in malaria-endemic countries has continued to increase. VFRs and immigrants from malaria-endemic countries now make up the majority of malaria patients in many nonendemic countries. Importantly, this group is characterized by various degrees of semi-immunity to malaria, resulting from repeated exposure to infection and a gradual decline of protection as a result of prolonged residence in non-malaria-endemic regions. Most studies indicate an effect of naturally acquired immunity in VFRs, leading to differences in the parasitological features, clinical manifestation, and odds for severe malaria and clinical complications between immune VFRs and nonimmune returning travelers. There are no valid data indicating evidence for differing algorithms for chemoprophylaxis or antimalarial treatment in semi-immune versus nonimmune malaria patients. So far, no robust biomarkers exist that properly reflect anti-parasite or clinical immunity. Until they are found, researchers should rigorously stratify their study results using surrogate markers, such as duration of time spent outside a malaria-endemic country.

Direct contact between Plasmodium falciparum and human B-cells in a novel co-culture increases parasite growth and affects B-cell growth.

BACKGROUND: Plasmodium falciparum parasites cause malaria and co-exist in humans together with B-cells for long periods of time. Immunity is only achieved after repeated exposure. There has been a lack of methods to mimic the in vivo co-occurrence, where cells and parasites can be grown together for many days, and it has been difficult with long time in vitro studies. METHODS AND RESULTS: A new method for growing P. falciparum in 5% CO2 with a specially formulated culture medium is described. This knowledge was used to establish the co-culture of live P. falciparum together with human B-cells in vitro for 10 days. The presence of B-cells clearly enhanced parasite growth, but less so when Transwell inserts were used (not allowing passage of cells or merozoites), showing that direct contact is advantageous. B-cells also proliferated more in presence of parasites. Symbiotic parasitic growth was verified using CESS cell-line and it showed similar results, indicating that B-cells are indeed the cells responsible for the effect. In malaria endemic areas, people often have increased levels of atypical memory B-cells in the blood, and in this assay it was demonstrated that when parasites were present there was an increase in the proportion of CD19 + CD20 + CD27 - FCRL4 + B-cells, and a contraction of classical memory B-cells. This effect was most clearly seen when direct contact between B-cells and parasites was allowed. CONCLUSIONS: These results demonstrate that P. falciparum and B-cells undoubtedly can affect each other when allowed to multiply together, which is valuable information for future vaccine studies.

Current mentorship practices in the training of the next generation of clinical microbiology and infectious disease specialists: an international cross-sectional survey.

The purpose of this study was to describe the current practice of mentorship in clinical microbiology (CM) and infectious diseases (ID) training, to identify possible areas for improvement and to assess the factors that are associated with satisfactory mentorship. An international cross-sectional survey containing 35 questions was answered by 317 trainees or specialists who recently completed clinical training. Overall, 179/317 (56%) trainees were satisfied with their mentors, ranging from 7/9 (78%) in non-European countries, 39/53 (74%) in Northern Europe, 13/22 (59%) in Eastern Europe, 61/110 (56%) in Western Europe, 37/76 (49%) in South-Western Europe to 22/47 (47%) in South-Eastern Europe. However, only 115/317 (36%) respondents stated that they were assigned an official mentor during their training. In multivariable logistic regression analysis, the satisfaction of trainees was significantly associated with having a mentor who was a career model (OR 6.4, 95%CI 3.5-11.7), gave constructive feedback on work performance (OR 3.3, 95%CI 1.8-6.2), and knew the family structure of the mentee (OR 5.5, 95%CI 3.0-10.1). If trainees felt overburdened, 70/317 (22%) felt that they could not talk to their mentors. Moreover, 67/317 (21%) stated that they could not talk to their mentor when unfairly treated and 59/317 (19%) felt uncertain. Training boards and authorities responsible for developing and monitoring CM&ID training programmes should invest in the development of high-quality mentorship programmes for trainees in order to contribute to the careers of the next generation of professionals.

How are trainees in clinical microbiology and infectious diseases supervised in Europe? An international cross-sectional questionnaire survey by the Trainee Association of ESCMID.

The purpose of this study was to map the supervision of European trainees in clinical microbiology and infectious diseases during their training. An international cross-sectional questionnaire survey of 38 questions was distributed among trainees and recently graduated medical specialists from European countries. Descriptive analyses were performed on both the total group of respondents and regionally. In total, 393 respondents from 37 different countries were included. The median of overall satisfaction with the supervisor was 4 (interquartile range 3-4) on a Likert scale (range 1, not satisfied at all-5, completely satisfied). Overall, merely 34% of respondents received constructive feedback from their supervisor on a regularly basis, 36% could evaluate their own supervisor, and just 63% were evaluated on their skills using a written plan. Fifty-two percent did not receive the opportunity to do a part of the specialty training abroad and 63% received support from their supervisors to be involved in research projects or publishing papers. A considerable proportion of trainees, mainly in Southern and Eastern European regions, felt that they did not receive sufficient supervision. This information may be useful in the pursuit of harmonizing the quality of training, achieving a common curriculum, and identifying robust and objective criteria to coach and evaluate trainees in a proper way.

Novel flow cytometry technique for detection of Plasmodium falciparum specific B-cells in humans: increased levels of specific B-cells in ongoing infection.

BACKGROUND: Malaria caused by Plasmodium falciparum is still a major health threat in endemic areas especially for children below 5 years of age. While it is recognized that antibody immunity plays an important role in controlling the disease, knowledge of the mechanisms of sustenance and natural boosting of immunity is very limited. Before, it has not been possible to investigate malaria specific B-cells directly in flow cytometry, making it difficult to know how much of a B cell response is due to malaria, or how much is due to other immunological stimulators. METHODS: This study developed a technique using quantum dots and schizont extract made from ghosts of infected erythrocytes, to be able to investigate P. falciparum specific B-cells, something that has never been done before. RESULTS: Major differences in P. falciparum specific B-cells were found between samples from immune (22.3 %) and non-immune (1.7 %) individuals. Samples from parasite positive individuals had the highest proportions of specific B-cells (27.9 %). CONCLUSION: The study showed increased levels of P. falciparum-specific B-cells in immune individuals, with the highest levels in active malaria infections, using a new technique that opens up new possibilities to study how these cells are sustained in vivo after natural infections. It will also be useful in vaccine studies.

Challenging the phylogenetic relationships among Echinococcus multilocularis isolates from main endemic areas.

Alveolar echinococcosis (AE) is a rare but severe disease that affects more than 18,000 people worldwide per year. The complete sequencing of the mitochondrial genome of Echinococcus multilocularis has made it possible to study the genetic diversity of the parasite and its spatial and temporal evolution. We amplified the whole mitochondrial genome by PCR, using one uniplex and two multiplex reactions to cover the 13,738 bp of the mitogenome, and then sequenced the amplicons with Illumina technology. In total, 113 samples from Europe, Asia, the Arctic and North America were analyzed. Three major haplogroups were found: HG1, which clustered samples from Alaska (including Saint-Lawrence Island), Yakutia (Russia) and Svalbard; HG2, with samples from Asia, North America and Europe; and HG3, subdivided into three micro-haplogroups. HG3a included samples from North America and Europe, whereas HG3b and HG3c only include samples from Europe. In France, HG3a included samples from patients more recently diagnosed in a region outside the historical endemic area. A fourth putative haplogroup, HG4, was represented by only one isolate from Olkhon Island (Russia). The increased discriminatory power of the complete sequencing of the E. multilocularis mitogenome has made it possible to highlight four distinct geographical clusters, one being divided into three micro-haplogroups in France.

A longitudinal study of plasma BAFF levels in mothers and their infants in Uganda, and correlations with subsets of B cells.

Malaria is a potentially life-threatening disease with approximately half of the world's population at risk. Young children and pregnant women are hit hardest by the disease. B cells and antibodies are part of an adaptive immune response protecting individuals continuously exposed to the parasite. An infection with Plasmodium falciparum can cause dysregulation of B cell homeostasis, while antibodies are known to be key in controlling symptoms and parasitemia. BAFF is an instrumental cytokine for the development and maintenance of B cells. Pregnancy alters the immune status and renders previously clinically immune women at risk of severe malaria, potentially due to altered B cell responses associated with changes in BAFF levels. In this prospective study, we investigated the levels of BAFF in a malaria-endemic area in mothers and their infants from birth up to 9 months. We found that BAFF-levels are significantly higher in infants than in mothers. BAFF is highest in cord blood and then drops rapidly, but remains significantly higher in infants compared to mothers even at 9 months of age. We further correlated BAFF levels to P. falciparum-specific antibody levels and B cell frequencies and found a negative correlation between BAFF and both P. falciparum-specific and total proportions of IgG+ memory B cells, as well as CD27- memory B cells, indicating that exposure to both malaria and other diseases affect the development of B-cell memory and that BAFF plays a part in this. In conclusion, we have provided new information on how natural immunity against malaria is formed.

B cell profiling in malaria reveals expansion and remodelling of CD11c+ B cell subsets.

Humoral immunity is important in limiting clinical disease in malaria, yet the longitudinal B cell response to infection remains unclear. We performed a 1-year prospective study in patients treated for acute P. falciparum malaria for the first time, or with previous exposure to the disease. Using an unbiased exploratory approach with mass cytometry, followed by targeted flow cytometry, we found that ~80% of mature B cells that proliferated in response to acute infection expressed CD11c. Only ~40% of CD11c+ B cells displayed an atypical B cell phenotype, with the remaining cells primarily made up of activated- and resting memory B cells. The CD11c+ B cells expanded rapidly following infection, with previous exposure to malaria resulting in a significantly larger increase compared to individuals with primary infection. This was attributed to an expansion of switched CD11c+ B cells that was absent in primary infected individuals. The rate of contraction of the CD11c+ B cell compartment was independent of previous exposure to malaria and displayed a slow decay with a half-life of ~300 days. Collectively, these results identify CD11c as a marker of B cells responding to malaria and further highlight differences in primary- and secondary B cell responses during infection.

Transport time for blood culture bottles: underlying factors and its consequences.

In the present study we investigated transport times for blood cultures from three tertiary-care hospitals to Karolinska University Laboratory and identified predictors of long transport times. Concomitantly, consequences of delayed incubation on total detection time (TDT) were analyzed by in vitro sepsis models. A total of 909 blood cultures were studied. The median (interquartile range) transport time was 9 (3-15) h. The hospital accommodating the microbiology laboratory had the shortest transport time compared to the other two hospitals (P < 0.0001). Samples taken between 16:00-24:00 had longer transport times compared to samples taken between 8:00-16:00 and 24:00-08:00 (P < 0.0001). In vitro experiments showed that TDT was longer for samples pre-incubated at room temperature (RT) for 19 h compared to the ones pre-incubated for 2 h or 9.5 h (P < 0.0001). In conclusion, off-site location, time of sampling and number of transports per day were related to, and predictors of transport time.