asenag

• Goren, Asena; Mysterud, Atle & Vindenes, Yngvild (2024). Modeling the effects of phenological mismatch in tick questing and host demographic turnover on Lyme disease hazard. Ecological Modelling. ISSN 0304-3800. 498. doi: 10.1016/j.ecolmodel.2024.110910. Full text in Research Archive Show summary

  Climate change is altering the seasonal abundance and activity patterns of ecologically interacting species. It is not yet known how changes in phenological alignment between ticks and their hosts will impact tick feeding, survival, and the timing and probability of pathogen transmission during feeding. It has been observed that the seasonal timing of human Lyme disease cases has shifted earlier, accompanying an increased incidence, which may reflect changes in tick questing phenology. We present a mathematical model framework for exploring the seasonal dynamics of a tick-borne pathogen. The model extends a recently developed seasonal population matrix model for ixodid ticks feeding on a small and a large host, to i) incorporate the transmission of a pathogen, based on the causative agent of Lyme disease, Borrelia burgdorferi sensu lato, between ticks and a reservoir-competent small mammal host, and ii) include seasonal demographic turnover in the small mammal host. Through modification of model parameters, we explored the effects of alternative scenarios for tick questing phenology, tick host selection, and seasonality of host reproduction on disease dynamics. Our model predicts that due to differences in their life history, seasonal infection prevalence is much more variable in the small mammalian host than in the tick vector. The rapid pace of host demographic turnover is important for clearing infection in the small mammal population. The alignment between the seasonal timing of host reproduction and tick questing phenology is a critical feature in the model, as it determines pathogen transmission and infection prevalence in host and vector populations. The model predicts that increased asynchrony between larval tick feeding and small host reproduction can increase the number of infected questing nymphs, a common metric for Lyme disease hazard. When larval tick feeding is misaligned with small host reproduction, the larvae feed predominantly on older hosts, which are more likely to be infected. Our model presents an adaptable framework for exploring seasonal relationships between pathogen dynamics, host demography, and vector life history traits in an emergent tick-borne disease system.

• Goren, Asena; Viljugrein, Hildegunn; Rivrud, Inger Maren; Jore, Solveig; Bakka, Haakon & Vindenes, Yngvild [Show all 7 contributors for this article] (2023). The emergence and shift in seasonality of Lyme borreliosis in Northern Europe. Proceedings of the Royal Society of London. Biological Sciences. ISSN 0962-8452. 290(1993). doi: 10.1098/rspb.2022.2420. Full text in Research Archive Show summary

  Climate change has had a major impact on seasonal weather patterns, resulting in marked phenological changes in a wide range of taxa. However, empirical studies of how changes in seasonality impact the emergence and seasonal dynamics of vector-borne diseases have been limited. Lyme borreliosis, a bacterial infection spread by hard-bodied ticks, is the most commonvector-borne disease in the northern hemisphere and has been rapidly increasing in both incidence and geographical distribution in many regions of Europe and North America. By analysis of long-term surveillance data (1995–2019) from across Norway (latitude 57°580–71°080 N), we demonstrate a marked change in the within-year timing of Lyme borreliosis cases accompanying an increase in the annual number of cases. The seasonal peak in cases is now six weeks earlier than 25 years ago, exceeding seasonal shifts in plant phenology and previous model predictions. The seasonal shift occurred predominantly in the first 10 years of the study period. The concurrent upsurgence in case number and shift in case timing indicate a major change in the Lyme borreliosis disease system over recent decades. This study highlights the potential for climate change to shape the seasonal dynamics of vector-borne disease systems. seasonality, vector-borne zoonoses,disease ecology, Lyme borreliosis,Lyme disease, climate change, ecology, health and disease and epidemiology

• Goren, Asena; Mysterud, Atle; Jore, Solveig; Viljugrein, Hildegunn; Bakka, Haakon & Vindenes, Yngvild (2023). Demographic patterns in Lyme borreliosis seasonality over 25 years. Zoonoses and Public Health. ISSN 1863-1959. 70(7), p. 647–655. doi: 10.1111/zph.13073. Full text in Research Archive Show summary

  Abstract Lyme borreliosis, the most common vector‐borne disease in Europe and North America, is attracting growing concern due to its expanding geographic range. The growth in incidence and geographic spread is largely attributed to climate and land‐use changes that support the tick vector and thereby increase disease risk. Despite a wide range of symptoms displayed by Lyme borreliosis patients, the demographic patterns in clinical manifestations and seasonal case timing have not been thoroughly investigated and may result from differences in exposure, immunity and pathogenesis. We analysed 25 years of surveillance data from Norway, supplemented by population demography data, using a Bayesian modelling framework. The analyses aimed to detect differences in case seasonality and clinical manifestations of Lyme borreliosis across age and sex differentiated patient groups. The results showed a bimodal pattern of incidence over age, where children (0–9 years) had the highest incidence, young adults (20–29 years) had low incidence and older adults had a second incidence peak in the ages 70–79 years. Youth (0–19 years) presented with a higher proportion of neuroborreliosis cases and a lower proportion of arthritic manifestations compared to adults (20+ years). Adult males had a higher overall incidence than adult females and a higher proportion of arthritis cases. The seasonal timing of Lyme borreliosis consistently occurred around 4.4 weeks earlier in youth compared to adults, regardless of clinical manifestation. All demographic groups exhibited a shift towards an earlier seasonal timing over the 25‐year study period, which appeared unrelated to changes in population demographics. However, the disproportionate incidence of Lyme borreliosis in seniors requires increased public awareness and knowledge about this high‐risk group as the population continues to age concurrently with disease emergence. Our findings highlight the importance of considering patient demographics when analysing the emergence and seasonal patterns of vector‐borne diseases using long‐term surveillance data.

View all works in NVA