Leptospirosis contributes substantially to acute undifferentiated fever (AUF) in sub-Saharan Africa but is underdiagnosed. Rapid diagnostic tests could enable early detection, yet the Leptocheck-WB has not been evaluated in Africa. We evaluated the Leptocheck-WB IgM rapid test in AUF patients at two health facilities in Hoima District, western Uganda (November 2023 to December 2024). Acute leptospirosis was defined by a composite reference standard combining lipL32 real-time PCR on blood and urine and the microscopic agglutination test (MAT) on paired sera. Two production batches were tested on acute-presentation whole blood and serum. Accuracy estimates carry exact binomial confidence intervals. Of 330 participants, 89 (27.0%, 95% CI 22.5-32.0) had leptospirosis. The first batch detected one of 89 cases (sensitivity of 1.1%, 0.03-6.1), and the second one detected two (2.2%, 0.3-7.9). Neither batch produced a false positive among 241 non-cases (specificity of 100%, 98.5-100). The test was negative in all 40 participants who were MAT-seropositive at presentation, including two with titres of 1:1600, while high-titre control sera reacted as expected. Across the 89 cases, MAT reactivity was dominated by the serogroup Bataviae (60 cases), followed by Australis (15) and Tarassovi (11), while Icterohaemorrhagiae was recorded in one case only, at a titre of 1:200. Sensitivity this low makes the test unsuitable for the screening or surveillance of acute leptospirosis in this setting. Limited cross-reactivity between the kit antigen and locally circulating strains is a plausible explanation that this study was not designed to test.

Leptospirosis is a re-emerging zoonosis responsible for approximately 1 million human infections and 59,000 deaths annually worldwide. In Europe, notification rates have increased by 5% per year since 2010, a trend compounded by climate change. The study was performed to document a fatal occupational case acquired through an under-recognised environmental exposure pathway, and to establish what regional surveillance data can and cannot support regarding its burden and exposure profile. We report a fatal case of occupational leptospirosis in a 56-year-old male beef cattle farmer in Lombardy (Po Valley, Italy) and describe the subsequent epidemiological investigation. Regional surveillance data, veterinary notifications, ECDC data, and an analysis of occupational and climate-related exposure pathways were reviewed. The index case was caused by a strain of serogroup Javanica (microscopic agglutination test titre 1:3,200 against serovar Poi), absent from standard regional animal serological screening panels, probably acquired through contaminated irrigation water. Among 16 confirmed leptospirosis cases in Lombardy over 22 months, 3 (18.8%) died and 1 (6.3%) had permanent disability (severe-outcome rate 25.0%, likely an underestimate given surveillance failures). Twelve of 16 cases (75.0%) had an agricultural-environmental exposure nexus. Leptospirosis risk in irrigated agriculture extends beyond livestock contact to environmental contamination of surface water by wildlife reservoirs. Climate change is expected to expand the disease's European distribution and extend the transmission season. A One Health approach integrating occupational medicine, veterinary surveillance, engineering controls, and climate-adaptive prevention is needed.

ObjectivesFeline Erythrocyte Antigen 6 (FEA 6) is a newly identified red blood cell (RBC) antigen in cats discovered following an unintentional sensitization event, suggesting it can be immunogenic. Its ability to consistently induce alloimmunization remains unknown. This prospective study evaluated FEA 6 immunogenicity in transfusion-naive, FEA 6-negative cats by assessing anti-FEA 6 alloantibody production and plasma levels. A secondary objective was to bank polyclonal anti-FEA 6 antibodies.MethodsFifty-three cats underwent AB and extensive blood typing for FEAs 1-6, naturally occurring alloantibody (NOAb) screening, and compatibility testing to select donor-recipient pairs. FEA 6 prevalence was assessed in 82 type A cats. Two transfusion-naive, FEA 6-negative cats received FEA 6-positive, otherwise compatible RBC transfusions and were monitored for anti-FEA 6 alloantibody production by gel column agglutination. Repeat transfusions were performed if alloantibodies became undetectable. Agreement between recipient-derived and reference anti-FEA 6 alloantibodies was evaluated in 51 type A cats using kappa statistics.ResultsFEA 6 prevalence among type A cats was 75.6% (62/82); NOAb were detected in 10.3% of screened type A cats, but none were directed against FEA 6. Both recipients developed anti-FEA 6 alloantibodies. Recipient 1 responded after two sensitizations, whereas recipient 2 responded after a single transfusion. Both reached peak titers of 1:8, with alloantibodies detectable through days 372 and 200, respectively. Recipient-derived anti-FEA 6 alloantibodies showed substantial agreement with the reference anti-FEA 6 antibody (κ = 0.64-0.78, P < .001) and almost perfect agreement with each other (κ = 0.87, P < .001).Conclusions and relevanceTransfusion of FEA 6-positive RBCs induced anti-FEA 6 alloantibodies in all transfusion-naive, FEA 6-negative recipients, supporting FEA 6 immunogenicity and its likely contribution to unexplained post-transfusion alloantibodies in cats. The resulting polyclonal antibodies may support FEA 6 typing and transfusion research, although more durable reagents remain needed.

Mycoplasma pneumoniae (MP)is a pathogen responsible for upper and lower respiratory tract infections. Arthritis, although uncommon, can occur as an extrapulmonary complication of MP infections in children. Diagnosis typically involves serological testing and nucleic acid amplification tests (NAATs), such as the loop-mediated isothermal amplification (LAMP) test, which is widely used in Japan because of its speed, sensitivity, and specificity. Here, we present a case of arthritis linked to an MP infection in a young child.A 2-year-old girl presented with a persistent fever and swelling of the proximal interphalangeal joints in both hands. Laboratory investigations showed elevated levels of C-reactive protein (CRP) and serum matrix metalloproteinase-3 (MMP-3). Musculoskeletal ultrasonography revealed synovial thickening and increased blood flow in the affected joints. Although the LAMP test for MP using throat swab specimens was negative, the MP antibody titer measured with the particle agglutination test was 1 : 640, indicating MP infection. Treatment with clarithromycin led to defervescence and normalization of both CRP and MMP-3 levels.This case suggests that arthritis may be a manifestation of an MP infection in young children. In pediatric cases of fever of unknown origin and arthritis, MP infection should be included in the differential diagnosis.

The clinical diagnosis of human leptospirosis is challenging owing to the non-specific nature of its symptoms, making laboratory confirmation essential. The microscopic agglutination test (MAT), recommended by the World Health Organisation as the reference serological method for diagnosing leptospirosis, requires ongoing efforts towards optimisation. The present study evaluated the impact of thermal inactivation of serum samples on MAT performance for the diagnosis of human leptospirosis. Thermal inactivation did not compromise antibody detection capacity. Discrepancies observed between inactivated and non-inactivated samples (8.4%; n = 11/131) were limited to minor titer variations and, in most cases, did not alter the study-defined case interpretation or the identification of the infecting serogroup. Furthermore, inactivation improved the clarity of agglutination reactions in some samples (n = 5).

Information on Leptospira spp. exposure in Mexican equids remains limited. This cross-sectional study evaluated seropositivity and antigen-specific seroreactivity in 313 apparently healthy equids enrolled by convenience sampling in Los Tuxtlas (n = 119), Sotavento (n = 108), and Capital (n = 86), Veracruz, Mexico, from 2 October 2023 to 6 March 2024. Sera were examined by the microscopic agglutination test (MAT) against 13 antigens; titers ≥ 1:100 defined seropositivity. Overall seropositivity was 57.5% (180/313; 95% confidence interval [CI]: 52.0-62.9), with regional proportions of 49.6%, 65.7%, and 58.1%, respectively (unadjusted p = 0.048). Modified Poisson models with robust variance were fitted separately for region with species and region with sex. For Sotavento versus Los Tuxtlas, the adjusted prevalence ratio was 1.33 after adjustment for species (95% CI: 1.06-1.67) and 1.33 after adjustment for sex (95% CI: 1.06-1.66). Antigen-specific seroreactivity was most frequent for Australis (63/313; 20.1%), Bratislava (62/313; 19.8%), and Pyrogenes (57/313; 18.2%); these are overlapping antigen responses, not mutually exclusive serogroup estimates. Environmental and management exposures were not measured at the animal level. The findings support surveillance at the animal-human-environment interface but do not demonstrate active shedding or zoonotic transmission.

Self-destructing attenuated adjuvant Salmonella (SDAAS) strains are next-generation attenuated S. Typhimurium strains designed to be used as live adjuvants. They possess diverse means to prevent persistence in vivo, survival if excreted, and to enhance the induction of innate immunity. In this study, we investigated whether SDAAS strains can be safely delivered to chicken embryos by in ovo inoculation without compromising hatchability or hatchling health. We then evaluated their growth in different media, sensitivity to complement-mediated killing, motility, serum agglutination, flagellar and LPS profiling, their ability to attach to and invade Int-407 cells, and the activation of different pattern recognition receptors displayed by HEK-Blue cells. We also determined whether these strains could induce protective immune responses in chicks following homologous challenge at day of hatch with a virulent S. Typhimurium strain by reducing intestinal colonization and organ invasion. Our findings demonstrate that SDAAS strains can be safely administered in ovo in a dose-dependent manner. Family A strains exhibit strict requirements for 2,6-diaminopimelic acid and D-alanine, while Family B strains demonstrate absolute dependence on L-arabinose for growth in liquid and solid media. Adjuvant strains demonstrate increased activation of murine receptors NOD1, NOD2, TLR4, TLR5, TLR8, and TLR9 in HEK-Blue cells compared to the parent strain χ3761, despite having lower rates of cell adhesion to and invasion of Int-407 cells. Lastly, we observed that in ovo administration of SDAAS strains reduced titers of S. Typhimurium recovered from birds as they became older, suggesting a time-dependent enhancement of protective immunity induced by SDAAS strains.

Mycoplasma synoviae (M. synoviae) is an avian pathogen responsible for respiratory disease and synovitis. The VlhA (variable lipoprotein hemagglutinin) family of surface adhesins plays a critical role in host cell attachment, yet the specific residues and structural determinants governing this interaction remain incompletely understood. In this study, we selected the C-terminal lipid-associated membrane hemagglutinin (LAM HA) domain within the VlhA family as the bait protein, based on its conserved C-terminal region. Yeast two-hybrid screening identified 18 LAM HA-interacting host proteins, and molecular docking pinpointed five residues (S83, R85, Y88, N124, K192) as the most frequent interaction hotspots. To assess their collective functional relevance, we constructed a combined deletion mutant lacking these five candidate residues. At the optimal pH of 6.0-6.5, wild-type LAM HA showed the highest titer (1:2), significantly exceeding that at pH 7.0-7.5 (no activity) and pH 5.0-5.5 (1:1) (p < 0.05), whereas the deletion mutant displayed a reduced titer (from 2 to 1; p = 0.05). Secondary structure analysis at the same pH revealed decreased α-helix content (from 7.90% to 7.57%), along with increased β-sheet (from 38.92% to 38.83%) and random coil (from 10.83% to 10.44%). Molecular dynamics simulations revealed that the deletion mutant exhibited elevated RMSF (from 2.83 ± 1.88 Å to 4.18 ± 2.65 Å) and Rg (from 40.48 ± 1.31 Å to 54.16 ± 4.47 Å) at pH 6.0-6.5, while RMSD showed a slight decrease (11.17 ± 1.33 Å vs. 12.14 ± 0.21 Å), collectively indicating compromised structural stability of the mutant. Collectively, these findings suggest that the LAM HA domain contributes to hemagglutination activity through pH-sensitive conformational stability and specific residue clusters-a property that may be relevant to M. synoviae colonization in the acidic microenvironments of the respiratory tract and synovial fluid during infection.

Non-ABO alloantibody-mediated acute hemolytic transfusion reactions are infrequent but life-threatening complications of red blood cell transfusion. Anti-Jk[b] antibodies are difficult to detect in routine pretransfusion screening due to their low titers, weak avidity, and transient persistence. Here, we report a 16-month-old patient with β-thalassemia major who developed AHTR following transfusion of Jk[b]-positive RBCs. The patient had received two prior transfusions without documented adverse reactions. However, following the third transfusion, the patient developed acute intravascular hemolysis within two hours, manifesting as tea-colored urine, fever (39.2 °C), and marked hyperbilirubinemia (total bilirubin 173.7 μmol/L). Hemoglobin declined from 62 g/L to 28 g/L over three days. Serologic workup revealed a positive direct antiglobulin test (1+), and antibody screening showed weak agglutination. Serologic workup confirmed the presence of anti-Jk[b] antibody. Further SCL14A1 genetic testing confirmed the absence of Jk[b] gene expression, and the patient's Kidd phenotype was determined as Jk (a+wb-). Subsequent transfusion of Jk[b]-negative, antigen-matched RBCs caused no hemolytic manifestations, and follow-up revealed that the patient's hemoglobin remained stable at approximately 90g/L following red blood cell transfusion. This case highlights the diagnostic challenges associated with anti-Jk[b] alloantibodies and illustrates the clinical features of an anamnestic alloimmune response. These findings underscore the importance of rigorous antibody screening and antigen-matched transfusion in chronically transfused patients with thalassemia.

Leptospirosis is a globally distributed zoonosis affecting domestic and wild species, particularly prevalent in regions with high temperature and humidity that favor leptospiral survival in the environment. This study investigated the role of wildlife-livestock interactions in the transmission cycle of Leptospira spp. Serum samples (for Microscopic Agglutination Test - MAT, considering dilutions ≥ 1:100 with ≥ 50% agglutination as reactive) and kidney tissues (for lipL32 PCR) were collected from 28 small mammals, including 14 marsupials and 14 rodents. All samples were seronegative by MAT; however, 15/28 (53.6%) kidney samples were PCR-positive, including 9/14 (64.3%) marsupials and 6/14 (42.9%) rodents. Additionally, 66 bovine serum samples from a dairy farm in the same area were analyzed by MAT, with 60/66 (90.9%) testing seropositive revealing high antibody titers (800), predominantly against serogroup Icterohaemorrhagiae (10%), followed by Sejroe (1.6%). Serogroup Pomona showed 1.6% of titers at 400. These findings suggest that small mammals might have played a significant role in the transmission and maintenance of pathogenic leptospires in the studied area, potentially acting as reservoirs and contributing to cattle infection. However, the observed infection patterns may also reflect indirect transmission routes, such as environmental persistence of leptospires in soil and water, or the involvement of additional, uninvestigated reservoir hosts within the agroecosystem. Therefore, small mammals sharing habitats with livestock should be considered important in leptospirosis epidemiology. Further studies evaluating leptospiral survival in environmental substrates, applying molecular typing to identify circulating strains, and conducting broader host surveillance are necessary to better elucidate transmission dynamics.