Biology subjects

Irrgang, C.

Publications and source records attributed to Irrgang, C..

3 recordsLinked to original sources

bioRxiv2026

The extrinsic incubation period for Zika virus: a Bayesian time delay modelling study

The extrinsic incubation period (EIP), defined as the time between a mosquito acquiring a virus and becoming capable of transmitting it, is a key component of arbovirus transmission and varies with temperature. For Zika virus (ZIKV), empirical estimates of EIP are derived from heterogeneous laboratory studies and are typically analysed without accounting for interval censoring inherent in vector competence experiments. We applied Bayesian interval-censored survival models to pooled individual-level observations from eight published studies, comparing 20 candidate models representing four parametric survival distributions and five temperature-response functions in Ae. aegypti and Ae. albopictus. Model performance was evaluated using approximate leave-one-out cross-validation. A lognormal survival model with a quadratic temperature response and study-level random intercept provided the best predictive performance. Median EIP declined non-linearly with increasing temperature, from 59.5 days (95% CrI 27.0-124.0) at 20{degrees}C to 8.4 days (3.8-17.0) at 32{degrees}C in Ae. aegypti. Across the temperature range examined, estimated EIPs for Ae. albopictus were approximately 1.5-fold longer than those for Ae. aegypti. Credible intervals widened at temperature extremes, reflecting between-study heterogeneity and limited data availability. These results provide a statistical framework for estimating temperature-dependent ZIKV EIP while accounting for censoring and uncertainty, supporting improved parameterisation of mechanistic models of arbovirus transmission. Author summaryWhen a mosquito feeds on an infected host, the virus must replicate and spread to the mosquitos salivary glands before it can be transmitted. This delay, known as the extrinsic incubation period (EIP), is a key determinant of mosquito-borne disease transmission and varies with temperature. For Zika virus (ZIKV), estimates of EIP come from laboratory studies that differ in experimental design, mosquito species, and viral dose, making them difficult to combine. We analysed data from eight studies using a Bayesian statistical approach that accounts for uncertainty in the time mosquitoes become infectious, because mosquitoes are typically tested only at discrete time points after infection. Our analysis showed that ZIKV EIP decreases non-linearly with increasing temperature, ranging from approximately 60 days at 20{degrees}C to approximately 8 days at 32{degrees}C in Aedes aegypti. Across temperatures, Aedes albopictus had consistently longer EIPs than Aedes aegypti. Compared with Bayesian EIP models developed for other arboviruses, including dengue, yellow fever, and West Nile virus, ZIKV showed a stronger non-linear temperature response. These estimates and their uncertainty provide improved parameters for models predicting when and where Zika transmission is most likely.

microbiology↗

bioRxiv2026

Suitable seasons: Global monthly habitat suitability for the arbovirus vectors Aedes aegypti and Aedes albopictus in 1975-2024

The mosquito species Aedes aegypti and Aedes albopictus are the primary vectors of the arboviruses dengue, Zika, and chikungunya. Expansion of these vectors into previously non-endemic regions due to climate and environmental changes has accelerated global burden from arboviral diseases. To combat this, predictive models accurately mapping Aedes habitats are essential for epidemiological modelling, effective vector control, and disease prevention. We introduce the Climademic Suitability Model, a machine learning model that delivers monthly global predictions of Aedes habitat suitability at 0.25{degrees} spatial resolution between 1975--2024. The model leverages integrated climate, land use, human population, and mosquito surveillance data to provide an explainable view of the factors governing habitat dynamics. SHAP-based explainability analysis identified temperature and dew point temperature as dominant features driving habitat suitability. Long-term analysis reveals a complex global redistribution of expanding and contracting vector habitats. Suitable areas for both species now encompass regions home to over 5 billion people, coinciding with the worlds most pronounced population growth and surpassing projections previously placing this threshold at 2050. The Climademic Suitability Model serves as a framework for near-real-time vector surveillance, climate scenario projection, and integration into transmission models to advance epidemic preparedness in an era of accelerating environmental change.

ecology↗

bioRxiv2025

The temperature sensitivity of arboviral disease extrinsic incubation periods: a systematic review

BackgroundArboviral diseases are an increasing global public health concern, driven by both human and environmental factors. A key parameter shaping transmission is the extrinsic incubation period (EIP)--the time between a mosquito acquiring a virus and becoming infectious--which is strongly influenced by temperature. However, the temperature-EIP relationship remains poorly characterized across arboviruses and mosquito species. MethodsWe conducted the first systematic review of laboratory studies evaluating temperature effects on EIP-related outcomes across all reported mosquito-arbovirus pairings. We searched three databases and extracted data on transmission efficiency (TE), applying linear regression models adjusted for diurnal temperature range and viral dose. Studies where TE could not be extracted were synthesized narratively. ResultsOur synthesis included 60 studies covering 17 arboviral diseases and 20 mosquito species. We found substantial heterogeneity in temperature effects on TE. While CHIKV, ZIKV, DENV, and WNV generally showed increased TE and shorter EIP at higher temperatures, many viruses--such as SINV, USUV, and BATV--exhibited no clear trends, often due to limited data and small sample sizes. Even across different vectors of the same virus, findings varied widely, reflecting both biological differences and inconsistent experimental designs. ConclusionsThese findings reveal major gaps in our understanding of climate-sensitive arbovirus transmission. Standardization of vector competence experiments and expanded research on neglected viruses are urgently needed. Environmental cofactors beyond temperature--such as humidity and variability--should also be incorporated to improve modelling and support climate-resilient intervention strategies. Author summaryThe burden of disease caused by arboviruses is increasing globally, largely driven by rapid urbanization, climate change, and global mobility. The transmission dynamics of arboviruses are modulated by a parameter known as the extrinsic incubation period, which is driven by environmental factors, especially temperature. However, the extent and direction of this effect has not been well characterized for all viruses, as data is limited and has not been synthesized for many neglected tropical diseases. Our study is the first systematic review to examine the existing evidence of laboratory studies across all studied mosquito species and virus pairings and to provide a comprehensive dataset for future modelling studies. We find that there is significant heterogeneity, not only between viruses, but also within individual vector-virus combinations, and that many arboviruses show no temperature effect. Based on these results, we propose that existing research efforts be standardized, and further research is conducted on emerging and re-emerging arboviruses for better intervention strategies and modelling predictions.

microbiology↗