ORCID Profile
0000-0002-1740-5675
Current Organisations
University of Oklahoma
,
North-West University , South Africa
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Publisher: The Royal Society
Date: 12-08-2019
Abstract: The risk of zoonotic spillover from reservoir hosts, such as wildlife or domestic livestock, to people is shaped by the spatial and temporal distribution of infection in reservoir populations. Quantifying these distributions is a key challenge in epidemiology and disease ecology that requires researchers to make trade-offs between the extent and intensity of spatial versus temporal s ling. We discuss s ling methods that strengthen the reliability and validity of inferences about the dynamics of zoonotic pathogens in wildlife hosts. This article is part of the theme issue ‘Dynamic and integrative approaches to understanding pathogen spillover’.
Publisher: The Royal Society
Date: 12-08-2019
Abstract: Pathogen circulation among reservoir hosts is a precondition for zoonotic spillover. Unlike the acute, high morbidity infections typical in spillover hosts, infected reservoir hosts often exhibit low morbidity and mortality. Although it has been proposed that reservoir host infections may be persistent with recurrent episodes of shedding, direct evidence is often lacking. We construct a generalized SEIR (susceptible, exposed, infectious, recovered) framework encompassing 46 sub-models representing the full range of possible transitions among those four states of infection and immunity. We then use likelihood-based methods to fit these models to nine years of longitudinal data on henipavirus serology from a captive colony of Eidolon helvum bats in Ghana. We find that reinfection is necessary to explain observed dynamics that acute infectious periods may be very short (hours to days) that immunity, if present, lasts about 1–2 years and that recurring latent infection is likely. Although quantitative inference is sensitive to assumptions about serology, qualitative predictions are robust. Our novel approach helps clarify mechanisms of viral persistence and circulation in wild bats, including estimated ranges for key parameters such as the basic reproduction number and the duration of the infectious period. Our results inform how future field-based and experimental work could differentiate the processes of viral recurrence and reinfection in reservoir hosts. This article is part of the theme issue ‘Dynamic and integrative approaches to understanding pathogen spillover’.
Publisher: Wiley
Date: 20-01-2022
DOI: 10.1111/CONL.12869
Abstract: Anthropogenic land use change is a major driver of zoonotic pathogen spillover from wildlife to humans. According to the land use‐induced spillover model, land use change alters environmental conditions that in turn alter the dynamics between zoonotic pathogens and their wildlife hosts. Thus, in response to the global spread of the SARS‐CoV‐2 virus (the agent of COVID‐19 disease), there have been renewed calls for landscape conservation as a disease preventive measure, including by the G7 Ministers responsible for Climate and the Environment. Landscape immunity, as a new construct, points to four paradigm shifts the world must favor to effectively mitigate pandemic risks. We provide a landscape immunity primer for policy makers and make the case for “world views” that place Homo sapiens within ecological systems, regard human health as an ecological service, prioritize investments in prevention, and apply ecological restoration to human health goals. Crisis is a conversation starter for reimagining and recommitting ourselves to what is most vital and generative. We urge world leaders to make the move to a nature‐positive world.
Publisher: Wiley
Date: 23-08-2018
DOI: 10.1111/NYAS.13910
Publisher: Wiley
Date: 30-10-2022
DOI: 10.1111/ELE.14007
Abstract: The ecological conditions experienced by wildlife reservoirs affect infection dynamics and thus the distribution of pathogen excreted into the environment. This spatial and temporal distribution of shed pathogen has been hypothesised to shape risks of zoonotic spillover. However, few systems have data on both long‐term ecological conditions and pathogen excretion to advance mechanistic understanding and test environmental drivers of spillover risk. We here analyse three years of Hendra virus data from nine Australian flying fox roosts with covariates derived from long‐term studies of bat ecology. We show that the magnitude of winter pulses of viral excretion, previously considered idiosyncratic, are most pronounced after recent food shortages and in bat populations displaced to novel habitats. We further show that cumulative pathogen excretion over time is shaped by bat ecology and positively predicts spillover frequency. Our work emphasises the role of reservoir host ecology in shaping pathogen excretion and provides a new approach to estimate spillover risk.
Publisher: Wiley
Date: 08-2018
DOI: 10.1002/PDS.4629
Publisher: Cold Spring Harbor Laboratory
Date: 19-08-2021
DOI: 10.1101/2021.08.19.457011
Abstract: The ecological conditions experienced by wildlife reservoir hosts affect the amount of pathogen they excrete into the environment. This then shapes pathogen pressure, the amount of pathogen available to recipient hosts over space and time, which affects spillover risk. Few systems have data on both long-term ecological conditions and pathogen pressure, yet such data are critical for advancing our mechanistic understanding of ecological drivers of spillover risk. To identify these ecological drivers, we here reanalyze shedding data from a spatially replicated, multi-year study of Hendra virus excretion from Australian flying foxes in light of 25 years of long-term data on changing ecology of the bat reservoir hosts. Using generalized additive mixed models, we show that winter virus shedding pulses, previously considered idiosyncratic, are most pronounced after recent food shortages and in bat populations that have been displaced to novel habitats. We next derive the area under each annual shedding curve (representing cumulative virus excretion) and show that pathogen pressure is also affected by the ecological conditions experienced by bat populations. Finally, we illustrate that pathogen pressure positively predicts observed spillover frequency. Our study suggests that recent ecological conditions of flying fox hosts are shifting the timing, magnitude, and cumulative intensity of Hendra virus shedding in ways that shape the landscape of spillover risk. This work provides a mechanistic approach to understanding and estimating risk of spillover from reservoir hosts in complex ecological systems and emphasizes the importance of host ecological context in identifying the determinants of pathogen shedding.
Publisher: Informa UK Limited
Date: 09-09-2016
DOI: 10.1080/14787210.2016.1227702
Abstract: In Zambia, antibiotics are categorized as prescription-only medicines. Antibiotics dispensed without a prescription pose a public health threat, which is a concern. Consequently, the aim is to ascertain the extent of non-prescription sales and dispensing of antibiotics in community pharmacies in Zambia. The practice of non-prescription sale and dispensing were assessed in 73 randomly selected community retail pharmacies, using a structured interviewer-administered questionnaire with simulated case scenarios. Majority (97%) stated that clients frequently requested non-prescribed antibiotics. Interviewees usually asked clients' indications (94%), counselled on dosing (96%) and suggested changes to antibiotic choices (97%). All (100%) dispensed non-prescribed antibiotics. Commonly dispensed antibiotics included amoxicillin (52%), cotrimoxazole (25%) and metronidazole (23%). Non-prescription sale and dispensing of antibiotics was significantly associated with interviewees' professional qualification in four out of five simulations. Non-prescription sale and dispensing of antibiotics is widespread in Zambia. Concerted public and professional interventions are needed coupled with stronger regulatory enforcement to reduce this.
Publisher: The Royal Society
Date: 24-08-0088
Abstract: Spillover of a pathogen from a wildlife reservoir into a human or livestock host requires the pathogen to overcome a hierarchical series of barriers. Interventions aimed at one or more of these barriers may be able to prevent the occurrence of spillover. Here, we demonstrate how interventions that target the ecological context in which spillover occurs (i.e. ecological interventions) can complement conventional approaches like vaccination, treatment, disinfection and chemical control. Accelerating spillover owing to environmental change requires effective, affordable, durable and scalable solutions that fully harness the complex processes involved in cross-species pathogen spillover. This article is part of the theme issue ‘Dynamic and integrative approaches to understanding pathogen spillover’.
No related grants have been discovered for Johanita Burger.