Epidemiological and clinical features of leptospirosis in a highly endemic area over three time periods.

OBJECTIVES: To present the features of human leptospirosis over three time periods (1970-1975; 2000-2005; 2010-2015), to compare the collected data and to determine whether the incidence, seasonal and spatial distribution, prevalence of presumptive infective serogroups and clinical features have changed over the last 50 years. METHODS: Epidemiological and clinical data obtained from patients hospitalised and treated in a well-known endemic focus of leptospirosis, Koprivnica-Krizevci County in Croatia, were analysed. RESULTS: We observed a steady decline in the overall incidence of leptospirosis and a change in the patient age distribution, with the age ratio changing in favour of middle-aged and older patients. Although leptospirosis was most frequently diagnosed in August in all time periods, the number of cases increased in autumn. The most prevalent serogroup during the first and the second time period was Icterohaemorrhagiae, while in the third time period, the serogroup Australis prevailed. We also noted an increase in the number of severe clinical manifestations. CONCLUSIONS: This retrospective research demonstrates a continuous decline in the incidence of human leptospirosis in Croatia. The pattern of disease has changed from predominantly mild clinical forms observed in children to more severe clinical forms observed in middle-aged to older patients, especially those working in agriculture. Additional epidemiological changes included an increase in the number of cases during the autumn months and changes in prevailing serogroups. Statistical analysis revealed a significant relationship between the severity of the clinical picture, patient age and presumed sources of infection.

Severe West Nile Virus Neuroinvasive Disease: Clinical Characteristics, Short- and Long-Term Outcomes.

West Nile Virus Neuroinvasive Disease (WNV NID) requires prolonged intensive care treatment, resulting in high mortality and early disability. Long-term results are lacking. We have conducted an observational retrospective study with a prospective follow-up of WNV NID patients treated at the Intensive Care Unit (ICU), University Hospital for Infectious Diseases, Zagreb, Croatia, 2013-2018. Short-term outcomes were vital status, length of stay (LOS), modified Rankin Scale (mRS), and disposition at discharge. Long-term outcomes were vital status and mRS at follow-up. Twenty-three patients were identified, 78.3% males, median age 72 (range 33-84) years. Two patients (8.7%) died in the ICU, with no lethal outcomes after ICU discharge. The median ICU LOS was 19 days (range 5-73), and the median hospital LOS was 34 days (range 7-97). At discharge, 15 (65.2%) patients had moderate to severe/mRS 3-5, 6 (26.0%) had slight disability/mRS 2-1, no patients were symptom-free/mRS 0. Ten (47.6%) survivors were discharged to rehabilitation facilities. The median time to follow-up was nine months (range 6-69). At follow-up, seven patients died (30.5%), five (21.7%) had moderate to severe/mRS 3-5, one (4.3%) had slight disability/mRS 2-1, six (26.1%) had no symptoms/mRS 0, and four (17.4%) were lost to follow-up. Briefly, ten (43.5%) survivors improved their functional status, one (4.3%) was unaltered, and one (4.3%) aggravated. In patients with severe WNV NID, intensive treatment in the acute phase followed by inpatient rehabilitation resulted in significant recovery of functional status after several months.

Prevalence and molecular epidemiology of West Nile and Usutu virus infections in Croatia in the 'One health' context, 2018.

In 2018, Croatia reported the largest outbreak of West Nile virus (WNV) infections as well as the re-occurrence of human Usutu virus (USUV) infections. For the first time, fatal WNV and USUV infections were detected in wild birds. We analysed epidemiological characteristics and molecular epidemiology of WNV and USUV infections detected during 2018 transmission season. From April to November, 178 patients with neuroinvasive disease and 68 patients with febrile disease were tested for WNV and USUV. Viral RNA was detected in cerebrospinal fluid (CSF) and urine samples using a real-time RT-PCR. Positive samples were tested by nested RT-PCR and nucleotide sequencing. IgM/IgG antibodies were detected in serum/CSF samples using ELISA with confirmation of cross-reactive samples by virus neutralization test (VNT). WNV neuroinvasive disease was confirmed in 54 and WNV fever in seven patients from 10 continental Croatian counties. Areas affected in 2018 were those in which cases occurred in previous seasons, while in three areas human cases were reported for the first time. Phylogenetic analysis of six strains from patients residing in different geographic areas showed circulation of WNV lineage 2. In three patients, neuroinvasive USUV infection was confirmed by RT-PCR or VNT. Sequence analysis of one detected strain revealed USUV Europe 2 lineage. During the same period, a total of 2,574 horse and 1,069 poultry serum samples were tested for WNV antibodies using ELISA. Acute asymptomatic WNV infection (IgM antibodies) was documented in 20/0.7% horses. WNV IgG antibodies were found in 307/11.9% horses and in 125/12.7% poultry. WNV RNA was detected in two goshawks and USUV RNA was detected in one blackbird from north-western Croatia. In the Zagreb area, 3,670 female mosquitoes were collected. One Culex pipiens pool collected in July tested positive for USUV RNA. Our results highlight the importance of continuous multidisciplinary 'One health' surveillance of these emerging arboviruses.