Peptide Biomarkers for the Diagnosis of Dengue Infection.

In a world with an increasing population at risk of exposure to arthropod-borne flaviviruses, access to timely and accurate diagnostic tests would impact profoundly on the management of cases. Twenty peptides previously identified using a flavivirus proteome-wide microarray were evaluated to determine their discriminatory potential to detect dengue virus (DENV) infection. This included nine peptides recognized by IgM antibodies (PM peptides) and 11 peptides recognized by IgG antibodies (PG peptides). A bead-based multiplex peptide immunoassay (MPIA) using the Luminex technology was set-up to determine Ab binding levels to each of these peptides in a panel of 323 carefully selected human serum samples. Sera are derived from individuals either infected with different viruses, namely, the four DENV serotypes, Zika virus (ZIKV), yellow fever virus (YFV), chikungunya virus (CHIKV), West Nile virus (WNV) and Human immunodeficiency virus (HIV), or receiving vaccination against YFV, tick-borne encephalitis (TBEV), and Japanese encephalitis virus (JEV). Additionally, a set of healthy controls were included. We targeted a minimum specificity of 80% for all the analysis. The PG-9 peptide had the best sensitivity (73%) when testing DENV sera from acute patients (A-DENV; <8 days since symptom onset). With sera from convalescent DENV patients (C-DENV; >10 days since symptom onset) the FPG-1 peptide was the best seromarker with a sensitivity of 86%. When combining all A-DENV and C-DENV samples, peptides PM-22 and FPG-1 had the best-diagnostic performance with a sensitivity of 60 and 61.1%, and areas under the curve (AUC) of 0.7865 and 0.8131, respectively. A Random forest (RF) algorithm was used to select the best combination of peptides to classify DENV infection at a targeted specificity >80%. The best RF model for PM peptides that included A-DENV and C-DENV samples, reached a sensitivity of 72.3%, while for PG peptides, the best RF models for A-DENV only, C-DENV only and A-DENV + C-DENV reached a sensitivity of 88.9%, 89.1%, and 88.3%, respectively. In conclusion, the combination of multiple peptides constitutes a founding set of seromarkers for the discrimination of DENV infected individuals from other flavivirus infections.

Infective endocarditis caused by Neisseria mucosa on a prosthetic pulmonary valve with false positive serology for Coxiella burnetii - The first described case.

We present a case of infective endocarditis (IE) on a prosthetic pulmonary valve in a 36-year-old patient with tetralogy of Fallot (TOF). The patient underwent valve replacement surgery and active antibiotic treatment against Gram-negative cocci (Piperacillin Tazobactam then Ceftriaxone) for a total duration of 42 days with a favourable outcome. The causative agent was Neisseria mucosa which was identified on the infected valve by sequencing of 16S ribosomal RNA. To our knowledge, this is the first described case of a N. mucosa infective endocarditis on a pulmonary valve. Initially, serologies performed in clinical settings by immunofluorescence for Coxiella burnetii antibodies showed a major increase in phase I IgG titers at 1024 (normal values <16) corresponding with the diagnostic criteria for Q fever endocarditis. However, this diagnosis could not be confirmed by the National Reference Center, making it the first reported case of a false positive serology for C. burnetii during an infection due to Neisseria spp.

Antibacterial mouthwash to prevent sexually transmitted infections in men who have sex with men taking HIV pre-exposure prophylaxis (PReGo): a randomised, placebo-controlled, crossover trial.

BACKGROUND: Bacterial sexually transmitted infections (STIs) are highly prevalent among men who have sex with men who use HIV pre-exposure prophylaxis (PrEP), which leads to antimicrobial consumption linked to the emergence of antimicrobial resistance. We aimed to assess use of an antiseptic mouthwash as an antibiotic sparing approach to prevent STIs. METHODS: We invited people using PrEP who had an STI in the past 24 months to participate in this single-centre, randomised, double-blind, placebo-controlled, AB/BA crossover superiority trial at the Institute of Tropical Medicine in Antwerp, Belgium. Using block randomisation (block size eight), participants were assigned (1:1) to first receive Listerine Cool Mint or a placebo mouthwash. They were required to use the study mouthwashes daily and before and after sex for 3 months each and to ask their sexual partners to use the mouthwash before and after sex. Participants were screened every 3 months for syphilis, chlamydia, and gonorrhoea at the oropharynx, anorectum, and urethra. The primary outcome was combined incidence of these STIs during each 3-month period, assessed in the intention-to-treat population, which included all participants who completed at least the first 3-month period. Safety was assessed as a secondary outcome. This trial is registered with Clinicaltrials.gov, NCT03881007. FINDINGS: Between April 2, 2019, and March 13, 2020, 343 participants were enrolled: 172 in the Listerine followed by placebo (Listerine-placebo) group and 171 in the placebo followed by Listerine (placebo-Listerine) group. The trial was terminated prematurely because of the COVID-19 pandemic. 151 participants completed the entire study, and 89 completed only the first 3-month period. 31 participants withdrew consent, ten were lost to follow-up, and one acquired HIV. In the Listerine-placebo group, the STI incidence rate was 140·4 per 100 person-years during the Listerine period, and 102·6 per 100 person-years during the placebo period. In the placebo-Listerine arm, the STI incidence rate was 133·9 per 100 person-years during the placebo period, and 147·5 per 100 person-years during the Listerine period. We did not find that Listerine significantly reduced STI incidence (IRR 1·17, 95% CI 0·84-1·64). Numbers of adverse events were not significantly higher than at baseline and were similar while using Listerine and placebo. Four serious adverse events (one HIV-infection, one severe depression, one Ludwig's angina, and one testicular carcinoma) were not considered to be related to use of mouthwash. INTERPRETATION: Our findings do not support the use of Listerine Cool Mint as a way to prevent STI acquisition among high-risk populations. FUNDING: Belgian Research Foundation - Flanders (FWO 121·00).

Promising application of monoclonal antibody against chikungunya virus E1-antigen across genotypes in immunochromatographic rapid diagnostic tests.

BACKGROUND: Three different genotypes of chikungunya virus (CHIKV) have been classified: East/Central/South African (ECSA), West African (WA), and Asian. Previously, a rapid immunochromatographic (IC) test detecting CHIKV E1-antigen showed high sensitivity for certain ECSA-genotype viruses, but this test showed poor performance against the Asian-genotype virus that is spreading in the American continents. We found that the reactivity of one monoclonal antibody (MAb) used in the IC rapid diagnostic test (RDT) is affected by a single amino acid substitution in E1. Therefore, we developed new MAbs that exhibited specific recognition of all three genotypes of CHIKV. METHODS: Using a combination of the newly generated MAbs, we developed a novel version of the IC RDT with improved sensitivity to Asian-genotype CHIKV. To evaluate the sensitivity, specificity, and cross-reactivity of the new version of the IC RDT, we first used CHIKV isolates and E1-pseudotyped lentiviral vectors. We then used clinical specimens obtained in Aruba in 2015 and in Bangladesh in 2017 for further evaluation of RDT sensitivity and specificity. Another alphavirus, sindbis virus (SINV), was used to test RDT cross-reactivity. RESULTS: The new version of the RDT detected Asian-genotype CHIKV at titers as low as 10^4 plaque-forming units per mL, a concentration that was below the limit of detection of the old version. The new RDT had sensitivity to the ECSA genotype that was comparable with that of the old version, yielding 92% (92 out of 100) sensitivity (95% confidence interval 85.0-95.9) and 100% (100 out of 100) specificity against a panel of 100 CHIKV-positive and 100 CHIKV-negative patient sera obtained in the 2017 outbreak in Bangladesh. CONCLUSIONS: Our newly developed CHIKV antigen-detecting RDT demonstrated high levels of sensitivity and lacked cross-reactivity against SINV. These results suggested that our new version of the CHIKV E1-antigen RDT is promising for use in areas in which the Asian and ECSA genotypes of CHIKV circulate. Further validation with large numbers of CHIKV-positive and -negative clinical samples is warranted. (323 words).

Potential usefulness of C-reactive protein and procalcitonin determination in patients admitted for neurological disorders in rural Democratic Republic of Congo.

In low-resource hospitals of central Africa, neurological disorders are frequent and etiologies very diverse. The difficulty to identify invasive bacterial infections in this setting results in major antibiotic overuse. Biomarkers such as C-reactive protein (CRP) and procalcitonin (PCT) may help discriminate these conditions. We retrospectively determined the concentrations of CRP and PCT in the sera of patients consecutively enrolled from 2012 to 2015 in an etiological study on neurological disorders at the rural hospital of Mosango, Democratic Republic of Congo. Invasive bacterial infection had been diagnosed by the demonstration of a bacterial pathogen in cerebrospinal fluid or blood cultures or the presence of radiological pneumonia. Sera of 313 (89.2%) and 317 (90.3%) of the 351 enrolled participants were available for determination of CRP and PCT concentrations respectively. Areas under the receiver operating characteristic curves for invasive bacterial infection, diagnosed in 19 tested cases, were 94.3% for CRP and 91.7% for PCT. No single case had a normal CRP concentration (<10 mg/L). Our data, although limited, suggest that CRP or PCT concentrations may help discriminate invasive bacterial infections in patients with neurological disorders in tropical settings and that normal CRP values could assist in withholding antibiotics.

Evaluation of the CellaVision DM96 advanced RBC application for screening and follow-up of malaria infection.

CellaVision DM96 is a digital cell morphology system for automated classification of white and red blood cells. CellaVision Advanced RBC application (ARBCA) pre-classifies RBC in 21 categories, including parasitized RBC, and allows re-classification by the operator. In this study, the performance of the software for detection of malaria and calculation of parasitemia was evaluated and compared to microscopy (n=40). For CellaVision, both pre- and post-reclassification results were evaluated. Sensitivity was moderate, even post-reclassification (72%), due to low numbers of analyzed RBC and limited resolution of photographs. CellaVision results correlated with microscopy according to Passing-Bablok analysis, with slightly lower values for CellaVision. Within-run, between-run and inter-observer variability were acceptable. The low sensitivity of CellaVision ARBCA precludes its use as a screening technique for malaria. However, due to its good correlation with microscopy and short turn-around-times, it may be useful in follow-up of parasitemia. Larger studies are required to confirm these findings.

Disseminated histoplasmosis: case report and review of the literature.

Case report We report the case of a young Cameroonian woman who presented with cough, hyperthermia, weight loss, pancytopenia, and hepatosplenomegaly. A positive HIV serology was discovered and a chest radiography revealed a 'miliary pattern'. Bone marrow aspiration pointed out yeast inclusions within macrophages. Given the morphological aspect, the clinical presentation and immunosuppression, histoplasmosis was retained as a working hypothesis. Antiretroviral and amphotericin B treatments were promptly initiated. Review Given the immigration wave that Europe is currently experiencing, we think it is important to share experience and knowledge, especially in non-endemic areas such as Europe, where clinicians are not used to face this disease. Histoplasmosis is due to Histoplasma capsulatum var. capsulatum, a dimorphic fungus. Infection occurs by inhaling spores contained in soils contaminated by bat or bird droppings. The clinical presentation depends on the immune status of the host and the importance of inoculum, varying from asymptomatic to disseminated forms. AIDS patients are particularly susceptible to develop a severe disease. Antigen detection, molecular biology techniques, and microscopic examination are used to make a rapid diagnosis. However, antigen detection is not available in Europe and diagnosis needs a strong clinical suspicion in non-endemic areas. Because of suggestive imagery, clinicians might focus on tuberculosis. Our case illustrates the need for clinicians to take histoplasmosis in the differential diagnosis, depending on the context and the patient's past history.

Unexpected Infection with Armillifer Parasites.

Visceral pentastomiasis is usually found incidentally during surgery. We describe a case of visceral pentastomiasis discovered during inguinoscrotal hernia surgery for a man from Benin, Africa. Because surgical removal of nymphs is needed for symptomatic patients only, this patient's asymptomatic pentastomiasis was not treated and he recovered from surgery uneventfully.

Toxocariasis diagnosed in international travelers at the Institute of Tropical Medicine, Antwerp, Belgium, from 2000 to 2013.

Although infection with Toxocara canis or T. catis (commonly referred as toxocariasis) appears to be highly prevalent in (sub)tropical countries, information on its frequency and presentation in returning travelers and migrants is scarce. In this study, we reviewed all cases of asymptomatic and symptomatic toxocariasis diagnosed during post-travel consultations at the reference travel clinic of the Institute of Tropical Medicine, Antwerp, Belgium. Toxocariasis was considered as highly probable if serum Toxocara-antibodies were detected in combination with symptoms of visceral larva migrans if present, elevated eosinophil count in blood or other relevant fluid and reasonable exclusion of alternative diagnosis, or definitive in case of documented seroconversion. From 2000 to 2013, 190 travelers showed Toxocara-antibodies, of a total of 3436 for whom the test was requested (5.5%). Toxocariasis was diagnosed in 28 cases (23 symptomatic and 5 asymptomatic) including 21 highly probable and 7 definitive. All but one patients were adults. Africa and Asia were the place of acquisition for 10 and 9 cases, respectively. Twelve patients (43%) were short-term travelers (< 1 month). Symptoms, when present, developed during travel or within 8 weeks maximum after return, and included abdominal complaints (11/23 symptomatic patients, 48%), respiratory symptoms and skin abnormalities (10 each, 43%) and fever (9, 39%), often in combination. Two patients were diagnosed with transverse myelitis. At presentation, the median blood eosinophil count was 1720/µL [range: 510-14160] in the 21 symptomatic cases without neurological complication and 2080/µL [range: 1100-2970] in the 5 asymptomatic individuals. All patients recovered either spontaneously or with an anti-helminthic treatment (mostly a 5-day course of albendazole), except both neurological cases who kept sequelae despite repeated treatments and prolonged corticotherapy. Toxocariasis has to be considered in travelers returning from a (sub)tropical stay with varying clinical manifestations or eosinophilia. Prognosis appears favorable with adequate treatment except in case of neurological involvement.

Vitros 5600 Syphilis TPA assay: evaluation of an automated chemiluminescence assay for detection of Treponema pallidum antibodies in a high prevalence setting.

The performance of the Syphilis TPA assay (Ortho-Clinical Diagnostics) on Vitros 5600 Integrated System was evaluated and demonstrated excellent results. Our data support the use of this assay for test confirmation in the traditional algorithm and for screening for syphilis in a routine automated laboratory setting when using the reverse algorithm.

A Schistosoma haematobium-specific real-time PCR for diagnosis of urogenital schistosomiasis in serum samples of international travelers and migrants.

BACKGROUND: Diagnosis of urogenital schistosomiasis by microscopy and serological tests may be elusive in travelers due to low egg load and the absence of seroconversion upon arrival. There is need for a more sensitive diagnostic test. Therefore, we developed a real-time PCR targeting the Schistosoma haematobium-specific Dra1 sequence. METHODOLOGY/PRINCIPAL FINDINGS: The PCR was evaluated on urine (n = 111), stool (n = 84) and serum samples (n = 135), and one biopsy from travelers and migrants with confirmed or suspected schistosomiasis. PCR revealed a positive result in 7/7 urine samples, 11/11 stool samples and 1/1 biopsy containing S. haematobium eggs as demonstrated by microscopy and in 22/23 serum samples from patients with a parasitological confirmed S. haematobium infection. S. haematobium DNA was additionally detected by PCR in 7 urine, 3 stool and 5 serum samples of patients suspected of having schistosomiasis without egg excretion in urine and feces. None of these suspected patients demonstrated other parasitic infections except one with Blastocystis hominis and Entamoeba cyst in a fecal sample. The PCR was negative in all stool samples containing S. mansoni eggs (n = 21) and in all serum samples of patients with a microscopically confirmed S. mansoni (n = 22), Ascaris lumbricoides (n = 1), Ancylostomidae (n = 1), Strongyloides stercoralis (n = 1) or Trichuris trichuria infection (n = 1). The PCR demonstrated a high specificity, reproducibility and analytical sensitivity (0.5 eggs per gram of feces). CONCLUSION/SIGNIFICANCE: The real-time PCR targeting the Dra1 sequence for S. haematobium-specific detection in urine, feces, and particularly serum, is a promising tool to confirm the diagnosis, also during the acute phase of urogenital schistosomiasis.

Diagnostic issues of acute schistosomiasis with Schistosoma mekongi in a traveler: a case report.

A Belgian traveler returning from Laos developed acute schistosomiasis. Feces microscopy and polymerase chain reaction (PCR) followed by sequence analysis revealed Schistosoma mekongi. Schistosome antibody test results and real-time PCR in serum were initially negative or not interpretable. A HRP-2 antigen test for Plasmodium falciparum and an enzyme-linked immunosorbent assay (ELISA) antibody test for Trichinella yielded false-positive results.

Infectious mononucleosis-like syndromes in febrile travelers returning from the tropics.

Infectious mononucleosis (IM), resulting from Epstein-Barr virus (EBV) infection, and IM-like syndromes, mainly due to cytomegalovirus (CMV), Toxoplasma gondii, or human immunodeficiency virus (HIV), have been occasionally reported in travelers returning from the tropics. Our objective was to investigate the prevalence, outcome, and diagnostic predictors of these syndromes in febrile travelers. Between April 2000 and March 2005, all febrile travelers and migrants presenting at our referral centers within 12 months after a tropical stay were prospectively included. We identified all patients serologically diagnosed with IM or IM-like syndrome and compared them with the rest of the cohort. During the 5-year period, 72/1,842 patients (4%) were diagnosed with an IM-like syndrome, including 36 CMV, 16 T gondii, 15 EBV, and 5 HIV primary infections. All patients were western travelers or expatriates. Mean delay before consultation was 2 weeks. Most patients had consulted other practitioners and/or received presumptive treatment. A minority of patients presented with IM clinical features. Lymphocytosis > or =40% of the white blood cells (WBC) and reactive/atypical lymphocyte morphology were observed in 60 and 30% of the patients. The four diseases were indistinguishable. Protracted fever and asthenia were common but complications rarely occurred. IM-like syndromes were independently associated with fever >7 days, lymphadenopathy, elevated liver enzymes, and lymphocytosis > or =40% of WBC. Diagnostic probability increased to >20% if at least three of these predictors were present. Diagnosis of IM and IM-like syndrome is not uncommon in febrile travelers, with a higher proportion of primary CMV, T gondii, and HIV infections than in nonimported series. Consequently, classic IM clinical and laboratory features are often lacking. All four pathogens should be systematically considered because early diagnosis should avoid unnecessary investigations and treatment and allow early intervention in case of primary HIV infection.

Diagnostic methods for differentiation of Entamoeba histolytica and Entamoeba dispar in carriers: performance and clinical implications in a non-endemic setting.

Unpreserved faecal samples, suspected to contain Entamoeba histolytica/Entamoeba dispar cysts or trophozoites on the basis of microscopic examination, and serum samples from 416 patients were collected in a prospective study to determine whether stool antigen assays and detection of antibodies in serum are reliable methods to distinguish between carriers of E. histolytica and E. dispar in comparison to the reference test: real-time PCR. In 283 patients (68%) DNA of E. histolytica or E. dispar was amplified by real-time PCR: 6 patients with amoebic colitis (2%), 19 carriers of E. histolytica (6.7%), and 258 carriers of E. dispar (91.2%). In 133 patients (31%) no DNA of E. histolytica or E. dispar could be amplified in the stool samples. This patient group was used as control for the evaluation of diagnostic tests. Using real-time PCR as a reference test, the sensitivity and specificity of (1) the Entamoeba test for the diagnosis of E. histolytica/E. dispar carrier were 59% and 98%, (2) E. histolytica II for the diagnosis of E. histolytica carrier was 71% and 100%, and (3) serology for the diagnosis of E. histolytica infection was 83.3% and 95.2%, respectively. Applied to carriers that did not originate from an endemic country the sensitivity of serology for E. histolytica infection was 90% and specificity was 98.8%. In comparison to real-time PCR the performances of Entamoeba test and E. histolytica II lacked sensitivity for a reliable diagnosis of E. histolytica/E. dispar infection in a non-endemic setting. In carriers of E. histolytica/E. dispar from non-endemic countries the high specificity of serology can be used to establish the diagnosis of E. histolytica infection if antibodies are present.

Imported Katayama fever: clinical and biological features at presentation and during treatment.

OBJECTIVES: To investigate the characteristics of imported Katayama fever (acute schistosomiasis) as well as evolution and outcome under treatment. METHODS: Between April 2000 and September 2004, we included prospectively all patients with confirmed diagnosis of Katayama fever. Follow-up was maintained at least until 6 months after symptoms resolved. Praziquantel (PZQ) was given as soon as the diagnosis was probable, most of the time with steroids. RESULTS: Twenty-three patients were diagnosed with Katayama fever by Schistosoma egg detection and/or by seroconversion. Clinical features were non-specific, with mainly respiratory and/or gastrointestinal symptoms. Diagnosis was confirmed at presentation in 17/23 (74%) patients, of whom 15 by serology. Immediate clinical exacerbation occurred in five of nine patients not given steroids concomitantly with PZQ. After initial resolution, fever recurred in five (22%) patients. When compiling initial and recurrent episodes (n=28), respiratory symptoms tended to occur at an earlier stage after exposure, while abdominal complaints were more frequent later. All patients were completely cured, sometimes after repeated treatments. CONCLUSIONS: Clinical presentation of Katayama fever is non-specific and involves respiratory and abdominal symptoms. Recurrence of fever is not unusual despite anti-helminthic treatment. Optimal therapeutic strategy remains to be defined to prevent recurrence.