In this study, we aimed to compare the performance of conventional PCR and real-time PCR assays as screening methods for identification of three frequent, clinically significant Salmonella serovars in Kazakhstan. We determined the diagnostic efficacy of three molecular methods for detection of S. enterica subsp. enterica and typing S. Typhimurium, S. Enteritidis, and S. Virchow. A total of 137 clinical samples and 883 food samples were obtained in Almaty in 2018–2019. All tests showed high analytical specificity for detecting S. enterica and its corresponding serovariants (100%). The sensitivity of real-time PCR for each of the tested targets was 1–10 microbial cells and in conventional PCR 10–100 microbial cells. The trials with conventional PCR and real-time PCR had a diagnostic efficacy (DE) of 100% and 99.71%, respectively. The DE of real-time PCR and conventional PCR for detecting S. Enteritidis and S. Typhimurium was 99.90%, while the DE of conventional PCR and real-time PCR for detecting S. Virchow was 99.31% and 99.80%, respectively. The RAPD-PCR analysis of the genomic DNA of Salmonella enterica showed the genetic kinship of S. Enteritidis isolates, and the genetic heterogeneity of S. Typhimurium and S. Virchow isolates. Thus, the developed methods can be considered as alternatives to classical serotyping using antisera.

Background. Stool microscopy and anti-Ascaris IgG serology assess different, but related biological domains. Joint interpretation can identify immunological exposure and intestinal egg shedding without assuming one or both markers are a measure of current infection independently. Objective. To develop a four-pattern paired-marker framework for anti-A. lumbricoides IgG and copromicroscopy results from adults in Kazakhstan and to assess the qualitative analytical concordance of two IgG enzyme-linked immunosorbent assays (ELISAs). Methods. The cross-sectional field study involved 1000 adult volunteers from Almaty and the region providing matched serum and stool samples. Sera were tested by MVA Group indirect anti-Ascaris IgG ELISA, and stool samples were examined by the Kato–Katz and Fülleborn methods. The binary outcome was classified into four pair patterns. All sera were further tested with a commercial ELISA (DRG), and qualitative concordance was calculated. Results. Anti-Ascaris IgG was found in 331 of the 1000 subjects (33.1%; 95% CI, 30.3–36.1%), while A. lumbricoides eggs were detected in 240 subjects (24.0%; 95% CI, 21.5–26.7%). The paired patterns were IgG-positive/egg-positive in 185 participants (18.5%), IgG-positive/egg-negative in 146 (14.6%), IgG-negative/egg-positive in 55 (5.5%), and IgG-negative/egg-negative in 614 (61.4%). IgG positivity was detected in 77.1% of subjects with detected eggs and 19.2% of subjects without detected eggs (odds ratio, 14.15; 95% CI, 9.96–20.09; p < 0.001). The MVA Group and DRG ELISAs agreed for 990 of 1000 specimens (99.0%; 95% CI, 98.2–99.5%), with positive and negative agreements of 98.2% and 99.4%, respectively (κ = 0.98). Conclusions. Serology and copromicroscopy showed a high association, but they are not interchangeable. The paired-marker paradigm clarified concordant and discordant patterns while retaining IgG as a marker of past or ongoing immune exposure and stool eggs as markers of shedding at the time of sampling. High inter-assay agreement suggests analytical consistency within this serum panel, but does not imply diagnostic accuracy for active ascariasis.

Background: The aim of the present study was to develop and optimize an experimental ELISA test system for the detection of IgG antibodies to Toxocara canis and subsequently apply it for the assessment of human and canine exposure in Uralsk, Kazakhstan, within a One Health framework. Methods: A native somatic antigen of T. canis was fractionated by gel filtration, and the working fraction was selected by SDS-PAGE and pilot ELISA. The optimized test system was used for the analysis of sera of 1000 adult volunteers. Antibody avidity was determined in IgG-positive human specimens, and human seropositivity was evaluated for associations with demographic and questionnaire-derived variables. Serum samples from 100 stray dogs were tested by ELISA and fecal samples by copromicroscopy. Agreement with the commercial DRG ELISA was tested with 50 positive and 50 negative human serum samples. Results: The antigen fraction of 18–22 kDa showed the best separation between positive and negative sera. IgG antibodies against T. canis were detected in 116/1000 volunteers (11.6%). Seropositivity was 17.0% in the 2025 sample and 6.2% in the 2026 sample (odds ratio 3.10; 95% confidence interval 2.01–4.77; p < 0.001). No significant associations were found with sex, age, residence, or questionnaire-derived variables. Among seropositive volunteers, 28.4% had low-avidity, 26.7% intermediate-avidity, 29.3% intermediate/high-avidity and 15.5% high-avidity IgG. Overall, 78/100 of the stray dogs were copropositive, and 93/100 were seropositive. All copropositive dogs were seropositive, and 15 additional seropositive dogs were copronegative. Agreement with the DRG ELISA was 97.0% (Cohen’s κ = 0.94). Conclusions: The experimental ELISA allowed the assessment of T. canis exposure of humans and dogs. Seropositivity in humans in Uralsk showed exposure. High seropositivity in dogs and frequent egg shedding showed a substantial canine reservoir and a potential for environmental contamination. These results support integrated surveillance and control within a One Health context.

Human toxocariasis is a globally distributed zoonosis caused by nematodes of the genus Toxocara, yet epidemiological data from Kazakhstan remain scarce. This study aimed to estimate the seroprevalence of anti-Toxocara antibodies and to assess potential risk factors among adults in northern Kazakhstan. A cross-sectional seroepidemiological study enrolled 1000 adult residents of the Pavlodar and North Kazakhstan regions (500 per region). Serum samples were tested for IgG antibodies against Toxocara spp. by ELISA and Western blot. Antibodies were detected by ELISA in 102 (10.2%; 95% CI: 8.5–12.2%) and by Western blot in 93 (9.3%; 95% CI: 7.7–11.3%) of the 1000 participants. Agreement between ELISA and WB was 99.1% (Cohen’s κ = 0.949; 95% CI: 0.916–0.982; p < 0.001). Seroprevalence was 10.0% (50/500) in Pavlodar and 8.6% (43/500) in North Kazakhstan (p = 0.514; OR = 1.18; 95% CI: 0.77–1.81). Univariate analysis revealed no statistically significant association between seropositivity and age, sex, place of residence (urban/rural), or any of the potential risk factors examined. These findings indicate exposure of the population of northern Kazakhstan to Toxocara spp. and support the use of two methods (ELISA and WB) in seroepidemiological surveys. Studies with broader geographic coverage are warranted.

Theileria annulata causes tropical theileriosis in cattle and is endemic in Kazakhstan. Although molecular diagnostic methods for this pathogen exist, data on its molecular surveillance and genetic diversity in Kazakhstan remain limited. This study aimed to develop and experimentally validate a species-specific real-time PCR (qPCR) assay for the detection of Theileria annulata and to conduct molecular surveillance and phylogenetic analysis of circulating isolates. A total of 709 cattle blood samples from 10 regions of Kazakhstan were analysed. Species-specific primers and a probe were designed targeting the 18S rRNA gene, and diagnostic performance was evaluated against sequencing as the reference method. Theileria annulata infection was confirmed in 110 of 709 samples (15.51%), with positive samples identified in the Turkistan, West Kazakhstan, Kyzylorda, and Zhambyl regions. The developed assay showed high diagnostic sensitivity (99.09%), specificity (99.67%), and diagnostic efficiency (99.58%), with no cross-reactivity with Theileria orientalis, Theileria parva, Babesia bovis, Babesia bigemina, or Anaplasma marginale. Phylogenetic analysis of partial 28S rRNA sequences confirmed the species identity of the detected isolates and demonstrated their close relationship with previously reported Kazakhstani and Chinese isolates. The developed qPCR assay is suitable for the molecular diagnosis and surveillance of bovine tropical theileriosis in Kazakhstan.

Regional surveys can help characterize adult exposure to Ascaris and assess the interpretation of different laboratory markers. This cross-sectional study examined 2001 volunteers from the Akmola, Pavlodar, and North Kazakhstan Regions during 2025–2026. Questionnaire data were collected, and paired serum and stool specimens were tested using the MVA GROUP IgG ELISA and Kato–Katz method. Associations with seropositivity were evaluated using multivariable logistic regression, and 300 selected sera were compared with the DRG Ascaris IgG ELISA. Overall seroprevalence was 28.0% (95% CI: 26.1–30.0%), with regional differences remaining after adjustment for age, sex, residence, and sampling year. Kato–Katz positivity was 8.4%, without a significant regional difference. ELISA sensitivity and specificity relative to Kato–Katz were 85.2% and 77.2%, respectively. Agreement with DRG was 95.0% (κ = 0.900). These findings support further regional assessment of adult exposure. Agreement between ELISAs supports consistent antibody classification in the selected panel, while discordance with Kato–Katz requires separate interpretation of antibody detection and intestinal egg shedding.