Ecological Origins of Novel Human Pathogen

Centre for Infectious Diseases, University of Edinburgh, Edinburgh, United Kingdom.
Critical Reviews in Microbiology (Impact Factor: 6.09). 02/2007; 33(4):231-42. DOI: 10.1080/10408410701647560
Source: PubMed

ABSTRACT A systematic literature survey suggests that there are 1399 species of human pathogen. Of these, 87 were first reported in humans in the years since 1980. The new species are disproportionately viruses, have a global distribution, and are mostly associated with animal reservoirs. Their emergence is often driven by ecological changes, especially with how human populations interact with animal reservoirs. Here, we review the process of pathogen emergence over both ecological and evolutionary time scales by reference to the "pathogen pyramid." We also consider the public health implications of the continuing emergence of new pathogens, focusing on the importance of international surveillance.

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    • "For such prevention to take place, timely and accurate prediction of outbreaks is critical. More than two thirds of emerging infectious diseases in recent decades are zoonotic in origin (crossing from animals to humans) [1, 2]. An example is the recent emergence of highly pathogenic avian influenza. "
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    ABSTRACT: Background Time series models can play an important role in disease prediction. Incidence data can be used to predict the future occurrence of disease events. Developments in modeling approaches provide an opportunity to compare different time series models for predictive power. Results We applied ARIMA and Random Forest time series models to incidence data of outbreaks of highly pathogenic avian influenza (H5N1) in Egypt, available through the online EMPRES-I system. We found that the Random Forest model outperformed the ARIMA model in predictive ability. Furthermore, we found that the Random Forest model is effective for predicting outbreaks of H5N1 in Egypt. Conclusions Random Forest time series modeling provides enhanced predictive ability over existing time series models for the prediction of infectious disease outbreaks. This result, along with those showing the concordance between bird and human outbreaks (Rabinowitz et al. 2012), provides a new approach to predicting these dangerous outbreaks in bird populations based on existing, freely available data. Our analysis uncovers the time-series structure of outbreak severity for highly pathogenic avain influenza (H5N1) in Egypt.
    BMC Bioinformatics 08/2014; 15(1):276. DOI:10.1186/1471-2105-15-276 · 2.67 Impact Factor
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    • "Only individuals living in dense forest (presumably with an abundant and diverse primate fauna) showed both polymerase chain reaction (PCR) and serological evidence of SFV infection, suggesting that transmission is greater in more intact forests (Wolfe et al. 2004). Intensive or sustained usage of areas of high biodiversity may also mediate the risk of other emerging and zoonotic diseases from a variety of reservoir hosts (Woolhouse and Gaunt 2007). For instance, the increased disease incidence documented where deforestation is occurring often cannot be ascribed directly to the loss of biodiversity that comes along with deforestation (and thus, to a dilution effect), but rather to the increase in human contact with forested habitat that deforestation entails (Wolfe et al. 2005). "
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    ABSTRACT: Control of human infectious disease has been promoted as a valuable ecosystem service arising from the conservation of biodiversity. There are two commonly discussed mechanisms by which biodiversity loss could increase rates of infectious disease in a landscape. First, loss of competitors or predators could facilitate an increase in the abundance of competent reservoir hosts. Second, biodiversity loss could disproportionately affect non-competent, or less competent reservoir hosts, which would otherwise interfere with pathogen transmission to human populations by, for example, wasting the bites of infected vectors. A negative association between biodiversity and disease risk, sometimes called the "dilution effect hypothesis," has been supported for a few disease agents, suggests an exciting win-win outcome for the environment and society, and has become a pervasive topic in the disease ecology literature. Case studies have been assembled to argue that the dilution effect is general across disease agents. Less touted are examples in which elevated biodiversity does not affect or increases infectious disease risk for pathogens of public health concern. In order to assess the likely generality of the dilution effect, we review the association between biodiversity and public health across a broad variety of human disease agents. Overall, we hypothesize that conditions for the dilution effect are unlikely to be met for most important diseases of humans. Biodiversity probably has little net effect on most human infectious diseases but, when it does have an effect, observation and basic logic suggest that biodiversity will be more likely to increase than to decrease infectious disease risk.
    Ecology 04/2014; 95(4):817-32. DOI:10.1890/13-1041.1 · 5.00 Impact Factor
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    • "A number of zoonoses are (re)emerging worldwide, the majority of which present risks to animal and human health [1], [2]. Birds are a key animal reservoir since they maintain and are responsible for the large-scale transmission of many infectious diseases [3]–. In recent years, a number of epidemic outbreaks originating in wild birds have been reported, such as outbreaks of West Nile virus or highly pathogenic H5N1 influenza virus, during which the virus later spread to other species of domestic animals and humans [7]–[11]. "
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    ABSTRACT: In recent years, a number of zoonotic flaviviruses have emerged worldwide, and wild birds serve as their major reservoirs. Epidemiological surveys of bird populations at various geographical scales can clarify key aspects of the eco-epidemiology of these viruses. In this study, we aimed at exploring the presence of flaviviruses in the western Mediterranean by sampling breeding populations of the yellow-legged gull (Larus michahellis), a widely distributed, anthropophilic, and abundant seabird species. For 3 years, we sampled eggs from 19 breeding colonies in Spain, France, Algeria, and Tunisia. First, ELISAs were used to determine if the eggs contained antibodies against flaviviruses. Second, neutralization assays were used to identify the specific flaviviruses present. Finally, for colonies in which ELISA-positive eggs had been found, chick serum samples and potential vectors, culicid mosquitoes and soft ticks (Ornithodoros maritimus), were collected and analyzed using serology and PCR, respectively. The prevalence of flavivirus-specific antibodies in eggs was highly spatially heterogeneous. In northeastern Spain, on the Medes Islands and in the nearby village of L'Escala, 56% of eggs had antibodies against the flavivirus envelope protein, but were negative for neutralizing antibodies against three common flaviviruses: West Nile, Usutu, and tick-borne encephalitis viruses. Furthermore, little evidence of past flavivirus exposure was obtained for the other colonies. A subset of the Ornithodoros ticks from Medes screened for flaviviral RNA tested positive for a virus whose NS5 gene was 95% similar to that of Meaban virus, a flavivirus previously isolated from ticks of Larus argentatus in western France. All ELISA-positive samples subsequently tested positive for Meaban virus neutralizing antibodies. This study shows that gulls in the western Mediterranean Basin are exposed to a tick-borne Meaban-like virus, which underscores the need of exploring the spatial and temporal distribution of this flavivirus as well as its potential pathogenicity for animals and humans.
    PLoS ONE 03/2014; 9(3):e89601. DOI:10.1371/journal.pone.0089601 · 3.23 Impact Factor
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