An Overview of Tick-Borne Encephalitis Epidemiology in Endemic Regions of Continental Croatia, 2017-2023.

Tick-borne encephalitis (TBE) represents an important public health problem in Europe. We analyzed the epidemiology of TBE based on data from humans, animals, and Ixodes ricinus ticks in endemic regions of continental Croatia. In the period from 2017 to 2023, cerebrospinal fluid (CSF) and serum samples of 684 patients with neuroinvasive diseases, 2240 horse serum samples, and 300 sheep serum samples were tested for TBEV. In addition, 8751 I. ricinus ticks were collected. CSF samples were tested using RT-PCR. Serological tests (serum, CSF) were performed using commercial ELISA, with confirmation of cross-reactive samples by a virus neutralization test. Eighty-four autochthonous human TBEV cases were confirmed. The majority of patients were in the age group of 40-69 years (58.3%) with a male predominance (70.2%). TBE showed a bimodal seasonality with a large peak in April-August and a small one in October-November. In addition to humans, TBEV IgG antibodies were found in 12.2% of horses and 9.7% of sheep. Seasonal tick abundance corresponds to the reported number of human infections. Continental Croatia is still an active natural focus of TBE. Continuous monitoring of infections in humans, sentinel animals, and ticks is needed for the implementation of preventive measures.

Coxiella burnetii (Q-fever) outbreak associated with non-occupational exposure in a semi-urban area of western Croatia in 2022.

In March 2022, an outbreak of Q fever (Coxiella burnetii) with non-occupational exposure was confirmed in a semi-urban area in Cavle, Croatia. Veterinary and human epidemiological investigations were conducted to identify the source of the outbreak and to implement appropriate control measures. Three farms were settled next to each other near the homes of the first human cases at the end of the street. The closest farm was less than 500 meters away. These farms contained 161 adult sheep and goats. Among the animal samples analysed, all 16 goats (100%) and 24/50 sheep (48%) tested positive for C. burnetii IgM/IgG antibodies, phase I and II. One out of five sheeps' vaginal swabs were C. burnetti DNA positive. Human testing revealed 20 confirmed and three probable cases (9/23 pneumonia, 2/23 hepatitis, 21/23 fever), with three hospitalizations, and one death. Twenty-seven cases were discarded following negative laboratory results. The epidemiological investigation revealed airborne transmission as the most likely route of transmission. Multiple logistic regression analyses were used to evaluate risk factors for Q fever infection. Persons who were near the farms (≤750 m) (OR 4.5; 95% CI = 1.1-18.3) and lived in the nearest street to the farms had the highest risk of contracting Q fever (OR 3.7; 95% CI = 1.1-13.6). Decreased rainfall compared to monthly averages was recorded in the months prior to the outbreak with several days of strong wind in January preceding the outbreak. This was the largest Q fever outbreak in the county in the last 16 years, which was unexpected due to its location and non-occupational exposure. To stop the outbreak, numerous intensive biosecurity measures were implemented. The outbreak highlights the importance of urban development strategies to limit the number of animal housing near residential areas while providing regular biosecurity measures to prevent infections in livestock.

Quantification of Antiviral Cytokines in Serum, Cerebrospinal Fluid and Urine of Patients with Tick-Borne Encephalitis in Croatia.

BACKGROUND: Tick-borne encephalitis virus (TBEV) is one of the most significant arboviruses affecting the human central nervous system (CNS) in Europe. Data on cytokine response in TBEV infection are limited. METHODS: We analyzed the cytokine response in serum, cerebrospinal fluid (CSF) and urine samples of patients with TBE. The control group consisted of patients with 'febrile headache' who had normal CSF cytology. The panel included 12 cytokines: TNF-α, IL-6, Th1 (IL-2, IFN-γ), Th2 (IL-4, IL-5, IL-13), Th9 (IL-9), Th17 (IL-17A, IL-17F), Th22 (IL-22) cytokines and IL-10. RESULTS: TBE patients were more likely to have increased levels of IL-6 and IFN-γ in CSF compared to controls (85.7% vs. 58.8% and 85.7% vs. 47.1%, respectively). However, concentrations of IL-6 (the most abundant cytokine in the CSF of both groups), IL-10 and IL-9 were lower in TBEV patients compared with controls, but the difference was statistically significant for IL-9 only (p = 0.001). By analyzing the cytokine levels in different clinical samples, all measured cytokines were detected in the serum, with the highest concentrations found for IFN-γ, TNF-α, IL-10, IL-17F and IL-22. Higher concentrations of cytokines in the CSF compared with serum were observed for IL-5, IL-6 and IL-22. All cytokines except IL-13 were detectable in urine but in a small proportion of patients, except for IL-22, which was detectable in 95.8% of patients. CONCLUSIONS: Cytokine composition in different clinical samples of TBE patients reveals a different network of early innate immune response cytokines, Th1, Th2, Th9, Th22, Th17 and anti-inflammatory cytokines.

Tick-borne encephalitis outbreak following raw goat milk consumption in a new micro-location, Croatia, June 2019.

In June 2019, the Croatian Institute of Public Health was informed of a cluster of patients with laboratory confirmed tick-borne encephalitis (TBE) from the Gorski Kotar region. Five of the six patients with TBE reported consuming raw (unpasteurized) goat milk in the two week period before symptom onset, and one reported a recent tick bite. To assess risk factors for infection, we selected six control individuals from among healthy family and community members, and conducted a case-control analysis. None of the cases or controls were vaccinated against TBE. Individuals with TBE (cases) had 25 (95 % CI 0.8-1410.2, p = 0.021) times higher odds of raw goat milk consumption compared to healthy controls. Milk samples from 12 goats from the implicated farm were tested for the TBE virus (TBEV) using RT-PCR. TBEV RNA was not detected in the milk, but serological testing of goats and other farm animals yielded evidence of exposure to the virus: Six goats from the flock had TBEV neutralizing antibodies. Our findings suggest that the vehicle for the outbreak was raw goat milk from a single farm. Following public health advice to cease consumption of raw dairy products, no further cases have been reported.

Mortality Characteristics of Two Populations in the Northern Mediterranean (Croatia) in the Period 1960⁻2012: An Ecological Study.

In the second half of the 20th century, the town of Bakar (Primorje-Gorski Kotar County, Croatia), where a coking plant was operational 1978⁻1994, experienced intensive industrialisation. The town of Mali Losinj (Primorje-Gorski Kotar County, Croatia) in this period based its economy on non-industrial sectors. The study goal was comparing mortality characteristics of these populations in the northern Mediterranean for 1960⁻2012. An ecological study design was used. Data were analysed for 1960⁻2012 for the deceased with recorded place of residence in the study area. Data on the deceased for 1960⁻1993 were taken from death reports, for 1994⁻2012 from digital archives of the Teaching Institute of Public Health, Primorje-Gorski Kotar County. Data on causes of death for 1960⁻1994 were recoded to the three-digit code of underlying cause of death according to the International Classification of Diseases (ICD⁻10). Among studied populations significant difference was found among the causes of deaths coded within ICD⁻10 chapters: neoplasms (particularly stomach carcinoma), mental and behavioural disorders and diseases of the respiratory system (particularly chronic obstructive pulmonary disease, (COPD)). Increase in mortality from neoplasms, increase in respiratory diseases for the area exposed to industrial pollution, also stomach carcinoma and COPD particularly in the town Bakar require further research.

Sexually Transmitted Diseases as a Risk for Acquiring HIV Infection among the Population of Men Who Have Sex with Men--A Case-Control Study.

At the beginning of the 1980-ies, HIV infection and AIDS were described for the first time, this among the population of men who have sex with other men. Nearly thirty years later, the MSM population is still a population under heightened risk for acquiring HIV infection and other sexually transmitted diseases. This study investigates sexually transmitted diseases as a risk for HIV infection. A total of 296 men who have sex with men (MSM) were included in this case control study. Differences among the frequencies of sexually transmitted diseases among the MSM of HIV positive and HIV negative status were tested. The history of HIV positive more often states falling ill with sexually transmitted diseases than this was the case before they became HIV positive, unlike those MSM who are not HIV infected (45.9%:11.1% that is OR 6.79, 95% CI 3.49-13.19). Hepatitis B infection is more frequent in HIV positive MSM (11.5%:1.9%; OR 6.58, 95% CI 1.86-23.3). The frequency of gonorrhea in case history of HIV positive MSM is significantly higher than in the HIV negative group (11.5%:3.8%, OR 3.24, 95% CI 1.13-9.34). In the group of HIV positive MSM, unlike the HIV negative group, syphilis (14.8:1.0%, OR 1774, 95% CI 3.43-122.87) and genital herpes (8.2%:0.5%, OR 18.39, 95% CI 2.03-424.7) are more frequent. The results of this study will be used in future preventive activities focused on the population of MSM, as a population under particular risk for acquiring sexually transmitted infections.

Epidemiological study of visual functions--refractive errors, macular degeneration and glaucoma in children in the Karst area of Opatija.

Authors of earlier studies examined the epidemiological characteristics of certain eye diseases: age-related macular degeneration (AMD), refractive errors and glaucoma in the area of Primorsho-goranska County (the island of Rab, Novi Vinodolshi and Delnice). It was found that the occurrence of AMD is most common on the island of Rab, followed by Novi Vinodolski and it is least common in Gorshi Kotar. This fact is associated with the intensity of solar radiation in the UV-A and UV-B fields. The highest percentage of the occurrence of glaucoma was also identified on the island of Rab. In comparison to this study, it was found that in the karst area of Opatija (Mune, Brgud, Zejane, Bresca, Zvonece, Pasjak, Sapjane and Zaluki) there is a very high incidence of glaucoma (27% suspected and 7% diagnosed glaucoma) within the indigenous population. Glaucoma does not appear among children whose parents migrated to the karst area of Opatija. Refractive errors are far less common among children of indigenous population than among the children whose parents migrated to this area. The occurrence ofAMD was not found in any child that was born and lives in this area, regardless of whether their parents are indigenous or not. This statement is very important because it confirms author's earlier statement which claims that at low exposure to solar UV-A and UV-B there is no occurrence of AMD.

Vaccine regulations in Croatia.

In this paper legal prerequisites for vaccine licensure in Croatia are discussed. The Croatian legislation concerning vaccine licensing, marketing authorisation and utilization is reviewed. The procedures for including a vaccine into the Mandatory Childhood Vaccination Programme are also discussed with focus on Human papillomavirus (HPV) vaccines. Non-obligatory vaccination recommendations are given when according to professional opinion; vaccination is beneficial for the vaccinee. There is little doubt that HPV vaccines should be recommended for preadolescent girls in Croatia. However, reaching a decision on its possible introduction into the Childhood Vaccination Programme will require careful consideration of the larger picture and a comparison of the cost-effectiveness of a mandatory vaccination against other competing public health priorities.