Полный текст

Across the five-year period, the year-specific counts reported in the surveillance summaries total 69 cases. The series is characterized by a sharp peak in 2022, followed by a decline in 2023 and a partial increase in 2024. Because the absolute numbers are small, percentage changes between adjacent years should be interpreted cautiously. The available age-specific data show a pronounced predominance of children younger than 14 years in 2022 and 2023, but this pattern was less marked in 2024.

Regional data were not presented with the same level of detail for every year. For 2020–2021, however, the largest number of cases was recorded in Almaty, with additional cases reported in Shymkent, East Kazakhstan Region, and Zhambyl Region. This supports the need for territorial surveillance but is insufficient on its own to establish a sustained geographic expansion across the entire 2020–2024 period.

Discussion

The national data show a low registered incidence of intestinal yersiniosis but substantial variation from year to year. The 2022 peak is the most prominent feature of the five-year series. When surveillance counts are small, relative increases and decreases can appear large even when the absolute difference is modest; therefore, the epidemiological interpretation should emphasize case counts, diagnostic practice, and reporting completeness alongside incidence rates.

The age distribution also requires a nuanced interpretation. Children younger than 14 years represented most registered cases in 2022 and 2023, supporting pediatric vigilance, but the 2024 distribution was less concentrated in this group. Thus, the available data support describing children as an important affected group rather than asserting a sustained increase in their proportion over the full observation period.

The comparison with other countries is useful mainly for understanding surveillance context rather than for direct ranking of disease burden, because diagnostic algorithms, laboratory capacity, reporting requirements, and foodborne-disease surveillance systems differ substantially.

International epidemiological context

International data indicate that the epidemiology of yersiniosis varies substantially between countries. In the Russian Federation, the etiological structure has shifted over time toward a greater proportion of intestinal yersiniosis: whereas pseudotuberculosis predominated in earlier periods, intestinal yersiniosis accounted for an increasing share of reported yersiniosis in the 2010s [14].

In the EU/EEA, the overall reported incidence in 2018 was 1.6 cases per 100,000 population, with the highest rates reported in Finland, the Czech Republic, Denmark, and Lithuania and the lowest in Romania and Bulgaria [15].

In 2020, 5,668 confirmed cases of yersiniosis were reported in 25 EU countries, with an overall incidence of 1.8 per 100,000 population. Hospitalization was reported for 29% of patients and mortality was low; Y. enterocolitica accounted for the great majority of human infections [16].

Germany and France were among the countries reporting high numbers of yersiniosis cases in 2020–2021 [17].

French surveillance data also described an increase in reported Y. enterocolitica isolates over the preceding decade, illustrating how diagnostic intensity and surveillance practice can influence observed trends [18,19].

In England, reported yersiniosis caused by Y. enterocolitica has fluctuated considerably over time, with renewed increases described from 2017 to 2020 and a possible contribution from the introduction of routine PCR testing [20].

The reported incidence in Ireland in 2020 was 0.26 per 100,000 population [21].

This figure was below the reported European average and broadly comparable with the United Kingdom [22].

Under-ascertainment remains a concern where routine screening is limited and culture, which has lower sensitivity than molecular methods, remains the principal diagnostic approach [23].

In the United States, Y. enterocolitica has been estimated to cause approximately 117,000 illnesses, 640 hospitalizations, and 35 deaths annually [24].

An annual incidence of approximately 1 case per 100,000 population has also been cited for the United States, with disease occurring particularly in young children [25].

New Zealand has reported substantially higher rates than many other industrialized countries; 1,202 cases were registered in 2018 and 1,186 in 2019, corresponding to 24.6 and 24.1 cases per 100,000 population, respectively [26].

Interpretation and implications for surveillance

The marked contrast between the low reported incidence in Kazakhstan and higher rates in several European countries and New Zealand should not be interpreted automatically as a true difference in transmission. Underdiagnosis, selective testing, limited use of molecular diagnostics, and variation in case ascertainment can all influence the number of registered infections. Strengthening laboratory capacity and integrating epidemiological and laboratory surveillance would therefore improve the interpretability of national trends.

From a prevention perspective, the findings support risk-oriented surveillance of foodborne and zoonotic transmission pathways, timely investigation of clusters, standardized regional reporting, and clinical awareness in pediatric practice. More complete territorial and age-specific data would allow future analyses to distinguish localized outbreaks from broader changes in endemic transmission.

Strengths and limitations

A strength of this study is the consolidation of five consecutive years of official national surveillance indicators with age-specific and territorial information where available. The principal limitations are the small number of registered cases, incomplete regional detail for some years, the absence of individual-level clinical or exposure data, and limited information on case-definition changes or diagnostic testing intensity. The contextual literature search was narrative; a reproducible systematic-search strategy, formal study selection flow, and risk-of-bias assessment were not available. These limitations restrict causal interpretation and cross-country comparability.

Conclusion

During 2020–2024, registered intestinal yersiniosis in Kazakhstan remained uncommon but showed pronounced year-to-year variability, with the highest annual count in 2022. Almaty accounted for the largest share of cases in the available 2020–2021 territorial data, and children younger than 14 years represented a particularly important affected group in 2022 and 2023.

The findings support continuous sanitary and epidemiological surveillance, improved laboratory diagnostics, harmonized regional reporting, and targeted preventive measures. Future national analyses would benefit from consistent age- and region-specific denominators, standardized diagnostic criteria, and linkage of epidemiological surveillance with laboratory data to determine whether observed fluctuations reflect changes in transmission, testing, or reporting.