Acute SARS-CoV-2 infections are not always diagnosed; hence an unknown proportion of all infections are not documented. SARS-CoV-2 can induce spike and nucleocapsid protein specific IgG antibodies, which can be detected in seroprevalence studies to identify a previous infection. However, with the introduction of vaccines containing the spike protein it is no longer possible to use spike-IgG as a marker of infection.
View Article and Find Full Text PDFBackground: Fever is a common symptom among travellers returning from tropical/subtropical areas to Europe, and promptly distinguishing severe illnesses from self-limiting febrile syndromes is important but can be challenging due to non-specific clinical presentation.
Methods: A cross-sectional study enrolled adults and children who sought care during 2015-2020 at Karolinska University Hospital, Stockholm, Sweden with fever within 2 months after returning from travel to a tropical/subtropical area. Data on symptoms and laboratory parameters were prospectively and retrospectively collected.
Fever is common among individuals seeking healthcare after traveling to tropical regions. Despite the association with potentially severe disease, the etiology is often not determined. Plasma protein patterns can be informative to understand the host response to infection and can potentially indicate the pathogen causing the disease.
View Article and Find Full Text PDFMpox (monkeypox) is an infection caused by the monkeypox virus, which belongs to the same family as the smallpox virus. Sporadic infections in humans have been known since the 1970s. Since spring 2022 there has been a global epidemic.
View Article and Find Full Text PDFWe performed 2 surveys during 2022 to estimate point prevalences of SARS-CoV-2 infection compared with overall seroprevalence in Sweden. Point prevalence was 1.4% in March and 1.
View Article and Find Full Text PDFWe compared cycle thresholds from mpox skin lesions with other specimen sites and over time from onset of clinical signs among 104 patients in Sweden. Cycle thresholds differed by anatomic site. We identified 2 early mpox cases from anorectal swab specimens after skin samples were negative, indicating necessity of sampling multiple sites.
View Article and Find Full Text PDFDuring respiratory viral infections, the precise roles of monocytes and dendritic cells (DCs) in the nasopharynx in limiting infection and influencing disease severity are incompletely described. We studied circulating and nasopharyngeal monocytes and DCs in healthy controls (HCs) and in patients with mild to moderate infections (primarily influenza A virus [IAV]). As compared to HCs, patients with acute IAV infection displayed reduced DC but increased intermediate monocytes frequencies in blood, and an accumulation of most monocyte and DC subsets in the nasopharynx.
View Article and Find Full Text PDFA previously healthy male patient had detectable monkeypox virus DNA in saliva 76 days after laboratory confirmation of infection. A comprehensive characterization of viral kinetics and a detailed follow-up indicated a declining risk for transmission during the weeks after monkeypox symptoms appeared.
View Article and Find Full Text PDFFollowing the report of a non-travel-associated cluster of monkeypox cases by the United Kingdom in May 2022, 41 countries across the WHO European Region have reported 21,098 cases and two deaths by 23 August 2022. Nowcasting suggests a plateauing in case notifications. Most cases (97%) are MSM, with atypical rash-illness presentation.
View Article and Find Full Text PDFNatural immunity to malaria develops over time with repeated malaria episodes, but protection against severe malaria and immune regulation limiting immunopathology, called tolerance, develops more rapidly. Here, we comprehensively profile the blood immune system in patients, with or without prior malaria exposure, over 1 year after acute symptomatic Plasmodium falciparum malaria. Using a data-driven analysis approach to describe the immune landscape over time, we show that a dampened inflammatory response is associated with reduced γδ T cell expansion, early expansion of CD16 monocytes, and parasite-specific antibodies of IgG1 and IgG3 isotypes.
View Article and Find Full Text PDFStrengthening malaria surveillance is a key intervention needed to reduce the global disease burden. Reliable serological markers of recent malaria exposure could improve current surveillance methods by allowing for accurate estimates of infection incidence from limited data. We studied the IgG antibody response to 111 Plasmodium falciparum proteins in 65 adult travellers followed longitudinally after a natural malaria infection in complete absence of re-exposure.
View Article and Find Full Text PDFBackground: The effect of primaquine in preventing Plasmodium vivax relapses from dormant stages is well established. For Plasmodium ovale, the relapse characteristics and the use of primaquine is not as well studied. We set to evaluate the relapsing properties of these 2 species, in relation to primaquine use among imported malaria cases in a nonendemic setting.
View Article and Find Full Text PDFMemory B cells (MBCs) are believed to be important for the maintenance of immunity to malaria, and these cells need to be explored in the context of different parasite antigens and their breadth and kinetics after natural infections. However, frequencies of antigen-specific MBCs are low in peripheral blood, limiting the number of antigens that can be studied, especially when small blood volumes are available. Here, we developed a multiplexed reversed B-cell FluoroSpot assay capable of simultaneously detecting MBCs specific for the four blood-stage antigens, MSP-1, MSP-2, MSP-3 and AMA-1.
View Article and Find Full Text PDFAnalysis of B-cell specificities at the single cell level provides important information on how the B-cell compartment responds when challenged by infection or vaccination. We recently developed a reversed B-cell FluoroSpot assay and showed that it could be used to detect B cells specific for different antigens simultaneously in a mouse model. The aim of this study was to further develop the method to detect and quantify antigen-specific memory B cells (MBCs) in humans where circulating antigen-specific cells are less frequent.
View Article and Find Full Text PDFBackground: The malaria parasite Plasmodium falciparum holds an extensive genetic polymorphism. In this pooled analysis, we investigate how the multiplicity in asymptomatic P. falciparum infections-that is, the number of coinfecting clones-affects the subsequent risk of clinical malaria in populations living under different levels of transmission.
View Article and Find Full Text PDFNK cells in the human lung respond to influenza A virus- (IAV-) infected target cells. However, the detailed functional capacity of human lung and peripheral blood NK cells remains to be determined in IAV and other respiratory viral infections. Here, we investigated the effects of IAV infection on human lung and peripheral blood NK cells and following clinical infection.
View Article and Find Full Text PDFHumoral 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.
View Article and Find Full Text PDFGlobal migration has resulted in a large number of asylum applications in Europe. In 2014, clusters of cases were reported among newly arrived Eritreans. This study aimed to assess malaria among Eritrean migrants in Europe from 2011 to 2016.
View Article and Find Full Text PDFBackground: Antibodies against merozoite antigens are key components of malaria immunity. The naturally acquired antibody response to these antigens is generally considered short-lived; however, the underlying mechanisms remain unclear. Prospective studies of travellers with different levels of prior exposure, returning to malaria-free countries with Plasmodium infection, offer a unique opportunity to investigate the kinetics and composition of the antibody response after natural infection.
View Article and Find Full Text PDFAccelerated cellular aging and reduced lifespan have recently been shown in birds chronically infected with malaria parasites. Whether malaria infection also affects cellular aging in humans has not been reported. Here, we assessed the effect of a single acute Plasmodium falciparum malaria infection on cellular aging dynamics in travelers prospectively followed over one year in Sweden.
View Article and Find Full Text PDFThe rapid clearance of malaria parasite DNA from circulation has widely been accepted as a fact without being systemically investigated. We assessed the persistence of parasite DNA in travelers treated for Plasmodium falciparum malaria in a malaria-free area. Venous blood was collected at the time of admission and prospectively up to one year.
View Article and Find Full Text PDF