Q fever in Kazakhstan: seroepidemiology, molecular evidence, and spatial distribution across livestock and ticks

Q fever, caused by Coxiella burnetii, remains a neglected zoonosis in Kazakhstan, with limited epidemiological data available. This study assessed the occurrence, spatial distribution, and risk factors of Q fever nationwide.

Between 2019 and 2024, 1,314 cattle and 1,689 small ruminants were sampled from 115 to 149 villages/cities, respectively, and 3,073 ticks were collected from 39 districts across Kazakhstan. Blood serum samples were screened for anti-C. burnetii antibodies by ELISA, while DNA from sheep milk and ticks was analyzed by qPCR, followed by partial sequencing of the 16 S rRNA and IS1111 genes. Multiple spacer sequence typing was performed on selected C. burnetii - positive samples. Risk factors were evaluated in a GEE model, and spatial risk maps were generated via inverse distance weighting interpolation. The apparent individual seroprevalence was significantly higher in small ruminants (30.6%; 95% CI: 28.4 - 32.9) than in cattle (6.6%; 95% CI: 5.3 - 8.1; p < 0.0001). Herd-level prevalence was 12.9% (95% CI: 8.4 - 17.6) in cattle and 60.2% (95% CI: 52.5 - 67.6; p < 0.0001) in small ruminants. Pavlodar oblast exhibited the highest individual and herd-level seroprevalence in both species, whereas low seroprevalence (≤ 11%) was observed in Atyrau, Mangystau, East Kazakhstan, and North Kazakhstan oblasts. Herd size was identified as a significant risk factor in both cattle and small ruminants. Coxiella burnetii DNA was detected in three of 77 (4%; 95% CI: 0.8 - 10.9) tested sheep milk samples. Overall, 7.6% of ticks (234/3,073; 95% CI: 6.7 - 8.6) tested positive for Coxiella spp., primarily H. scupense and D. niveus, likely including non-pathogenic endosymbionts. Thirteen samples were successfully sequenced and showed 99.7%-100% nucleotide identity in the IS1111 gene with reference C. burnetii isolates. The allele profile identified in the present study for the loci Cox2 - Cox5 - Cox18 was 3-8-15.

Q fever should be regarded as a potentially underrecognized and underreported infection in Kazakhstan. The exceptionally high prevalence observed in Pavlodar oblast in small ruminants and cattle underscores the urgent need to initiate monitoring of Q fever in the human population.