Eurosurveillance - Volume 30, Issue 4, 30 January 2025

Crimean–Congo haemorrhagic fever (CCHF) is a severe illness characterised by fever, bleeding and high case-fatality rates. The disease is caused by CCHF virus (CCHFV), transmitted by ticks and infectious body fluids and tissues.

After CCHF was diagnosed in three persons in 2023, we aimed to investigate the presence of antibodies against CCHFV in healthcare workers (HCW), sheep and goats, and of CCHFV in ticks, in an area in North Macedonia and characterise virus strains.

In 2023, we collected blood samples from HCWs involved in treating CCHF patients and sera and ticks from sheep and goats in the village in North Macedonia where the index case resided. The blood samples were analysed by ELISA. Ticks were tested for presence of CCHFV, and the virus from a CCHF case was sequenced.

Samples from four of 52 HCWs and 10 of 17 small ruminants had antibodies against CCHFV. The virus was not detected from any of the 24 Rhipicephalus bursa ticks. The virus strain from the index case clustered with regional strains within the Europe-1 lineage (genotype V) group and was closest to strains from Kosovo^‡.

This report shows CCHFV is endemic in North Macedonia. Raising awareness of the risk factors and educating people about the measures they can take to reduce exposure to the virus is important. Healthcare workers need to be aware of the disease. Early detection, robust diagnostic methods, surveillance and collaborative efforts are necessary to prevent and control CCHF in the affected regions.

Tick-borne encephalitis (TBE) can be a severe neurological disease. Identifying ecological factors that may facilitate tick-borne encephalitis virus (TBEV) circulation in the Netherlands could improve awareness and detection.

We aimed to identify ecological factors affecting TBEV circulation in the Netherlands and to determine if there is sustained circulation and spread of the virus.

Between June and September 2021, rodents and ticks from three previously TBEV-positive locations were tested for TBEV by PCR. We sequenced TBEV and compared the sequences with previous and subsequent sequences from the Netherlands and other countries to investigate the spread of TBEV-variants.

We captured 383 rodents, 928 feeding ticks and 1,571 questing Ixodes ticks and detected TBEV from six (three Apodemus sylvaticus and three Clethrionomys glareolus) (2.9%) of 206 tested rodents and two (0.9%) of 215 questing tick pools. Detection of TBEV was associated with questing tick density (Mann–Whitney U test  = 81.5; 95% confidence interval (CI): − 3.7–6.3 × 10⁻⁵; p = 0.05). Tick larvae (odds ratio (OR) = 9.0; 95% CI: 2.8–38.2; p < 0.01) and nymphs (OR = 3.8; 95% CI: 1.3–13.6; p < 0.01) were more frequent on A. sylvaticus than on C. glareolus. Sequence comparisons suggest multiple introductions and local circulation of TBEV but no spread among locations.

Tick-borne encephalitis virus occurs in diverse woodlands in the Netherlands, posing a risk to those frequenting these areas. Surveillance for the early detection and monitoring of TBEV spread, along with public awareness campaigns on preventive measures, should continue. Recognition of TBE symptoms and supportive diagnostics should be made available nationwide.