Biology subjects

Erazo, D.

Publications and source records attributed to Erazo, D..

3 recordsLinked to original sources

bioRxiv2021

The impact of resource provisioning on the epidemiological responses of different parasites

O_LIEvents such as anthropogenic activities and periodic tree masting can alter resource provisioning in the environment, directly affecting animals, and potentially impacting the spread of infectious diseases in wildlife. The effect of these supplemental resources on infectious diseases can manifest through different pathways, affecting host susceptibility, transmission and host demography. C_LIO_LITo date however, empirical research has tended to examine these different pathways in isolation, for example by quantifying the effects of provisioning on host behaviour in the wild or changes in immune responses in controlled laboratory studies. Further, while theory has investigated the interactions between these pathways, thus far this work has focussed on a narrow subset of pathogen types, typically directly-transmitted microparasites. Given the diverse ways that provisioning can affect host susceptibility, contact patterns or host demography, we may expect the epidemiological consequences of provisioning to depend on key aspects of parasite life-history, such as the duration of infection and transmission mode. C_LIO_LIWe developed a suite of generic epidemiological models to compare how resource provisioning alters responses for different parasites that vary in their biology (micro- and macro-parasite), transmission mode (direct, environmental, and vector transmitted) and duration of infection (acute, latent, and chronic). Next, we parameterised these different parasite types using data from the diverse parasite community of wild wood mice as a case study. C_LIO_LIWe show there are common epidemiological responses to host resource provisioning across all parasite types examined. In particular, the response to provisioning could be driven in opposite directions, depending on which host pathways (contact rate, susceptibility or host demography) are most altered by the addition of resources to the environment. Broadly, these responses were qualitatively consistent across all parasite types, emphasising the importance of identifying general trade-offs between provisioning-altered parameters. C_LIO_LIDespite the qualitative consistency in responses to provisioning across parasite types, we found notable quantitative differences between parasites, suggesting specific epidemiological outcomes could strongly depend on parasite type, infection duration and permanency of recovery, and whether the parasite is directly, environmentally, or vector transmitted. These analyses therefore highlight the importance of knowing key specific aspects of host-parasite biology, such as host contact behaviours, parasite interactions with the host immune system, and how resource availability shapes host demographics, in order to understand and predict epidemiological responses to provisioning for any specific host-parasite system. C_LI

ecology↗

bioRxiv2020

Who acquires infection from whom? Estimating herpesvirus transmission rates between wild rodent host groups

To date, few studies of parasite epidemiology have investigated who acquires infection from whom in wildlife populations. Nonetheless, identifying routes of disease transmission within a population, and determining the key groups of individuals that drive parasite transmission and maintenance, are fundamental to understanding disease dynamics. Gammaherpesviruses are a widespread group of DNA viruses that infect many vertebrate species, and murine gammaherpesviruses (i.e. MuHV-4) are a standard lab model for studying human herpesviruses, for which much about the pathology and immune response elicited to infection is well understood. However, despite this extensive research effort, primarily in the lab, the transmission route of murine gammaherpesviruses within their natural host populations is not well understood. Here, we aimed to understand wood mouse herpesvirus (WMHV) transmission, by fitting a series of population dynamic models to field data on wood mice naturally infected with WMHV and then estimating transmission parameters within and between demographic groups of the host population. Different models accounted for different combinations of host sex (male/female), age (subadult/adult) and transmission functions (density/frequency-dependent). We found that a density-dependent transmission model incorporating explicit sex groups fitted the data better than all other proposed models. Male-to-male transmission was the highest among all demographic groups, suggesting that male behaviour is a key factor driving WMHV transmission. Our models also suggest that transmission between sexes, although important, wasnt symmetrical, with infected males playing a significant role in infecting naive females but not vice versa. Overall this work shows the power of coupling population dynamic models with long-term field data to elucidate otherwise unobservable transmission processes in wild disease systems.

ecology↗

bioRxiv2019

Is vectorial transmission of Trypanosoma cruzi an efficient route to support high infection rates in sylvatic hosts?"

Chagas disease is caused by the parasite Trypanosoma cruzi and it is transmitted to humans by the triatomine bug Rhodnius prolixus. The main insect vector in the Andean countries presents sylvatic and domestic cycles involving humans, insects and reservoirs (e.g small mammals). It is commonly assumed that vectorial transmission is the main route for parasite spread between hosts. Recent studies have reported high percentages (21-80%) of infected opossums (Didelphis marsupialis) in the sylvatic cycle, raising the question of whether such a high proportion of infected could be only maintained by vectorial transmission, a seemingly inefficient pathway. To address this question, we formulated a mathematical model that describes the sylvatic transmission dynamics considering vectors and hosts and parametrized with field data. Our results show that vectorial transmission it is not sufficient to explain such high percentages of infected host-mammals reported in the literature. Here we propose oral transmission as an alternate route of transmission that may increase the number of infected individuals found in field studies.

ecology↗