Did Neoliberalizing West African Forests Produce a New Niche for Ebola?

A recent study introduced a vaccine that controls Ebola Makona, the Zaire ebolavirus variant that has infected 28,000 people in West Africa. We propose that even such successful advances are insufficient for many emergent diseases. We review work hypothesizing that Makona, phenotypically similar to much smaller outbreaks, emerged out of shifts in land use brought about by neoliberal economics. The epidemiological consequences demand a new science that explicitly addresses the foundational processes underlying multispecies health, including the deep-time histories, cultural infrastructure, and global economic geographies driving disease emergence. The approach, for instance, reverses the standard public health practice of segregating emergency responses and the structural context from which outbreaks originate. In Ebola's case, regional neoliberalism may affix the stochastic "friction" of ecological relationships imposed by the forest across populations, which, when above a threshold, keeps the virus from lining up transmission above replacement. Export-led logging, mining, and intensive agriculture may depress such functional noise, permitting novel spillovers larger forces of infection. Mature outbreaks, meanwhile, can continue to circulate even in the face of efficient vaccines. More research on these integral explanations is required, but the narrow albeit welcome success of the vaccine may be used to limit support of such a program.SCOPUS: re.jinfo:eu-repo/semantics/publishe

Did Ebola emerge in West Africa by a policy-driven phase change in agroecology? Ebola's social context

SCOPUS: no.jinfo:eu-repo/semantics/publishe

Flying Over an Infected Landscape: Distribution of Highly Pathogenic Avian Influenza H5N1 Risk in South Asia and Satellite Tracking of Wild Waterfowl

Highly pathogenic avian influenza (HPAI) H5N1 virus persists in Asia, posing a threat to poultry, wild birds, and humans. Previous work in Southeast Asia demonstrated that HPAI H5N1 risk is related to domestic ducks and people. Other studies discussed the role of migratory birds in the long distance spread of HPAI H5N1. However, the interplay between local persistence and long-distance dispersal has never been studied. We expand previous geospatial risk analysis to include South and Southeast Asia, and integrate the analysis with migration data of satellite-tracked wild waterfowl along the Central Asia flyway. We find that the population of domestic duck is the main factor delineating areas at risk of HPAI H5N1 spread in domestic poultry in South Asia, and that other risk factors, such as human population and chicken density, are associated with HPAI H5N1 risk within those areas. We also find that satellite tracked birds (Ruddy Shelduck and two Bar-headed Geese) reveal a direct spatio-temporal link between the HPAI H5N1 hot-spots identified in India and Bangladesh through our risk model, and the wild bird outbreaks in May–June–July 2009 in China (Qinghai Lake), Mongolia, and Russia. This suggests that the continental-scale dynamics of HPAI H5N1 are structured as a number of persistence areas delineated by domestic ducks, connected by rare transmission through migratory waterfowl

Host shifts and molecular evolution of H7 avian influenza virus hemagglutinin

Evolutionary consequences of host shifts represent a challenge to identify the mechanisms involved in the emergence of influenza A (IA) viruses. In this study we focused on the evolutionary history of H7 IA virus in wild and domestic birds, with a particular emphasis on host shifts consequences on the molecular evolution of the hemagglutinin (HA) gene. Based on a dataset of 414 HA nucleotide sequences, we performed an extensive phylogeographic analysis in order to identify the overall genetic structure of H7 IA viruses. We then identified host shift events and investigated viral population dynamics in wild and domestic birds, independently. Finally, we estimated changes in nucleotide substitution rates and tested for positive selection in the HA gene. A strong association between the geographic origin and the genetic structure was observed, with four main clades including viruses isolated in North America, South America, Australia and Eurasia-Africa. We identified ten potential events of virus introduction from wild to domestic birds, but little evidence for spillover of viruses from poultry to wild waterbirds. Several sites involved in host specificity (addition of a glycosylation site in the receptor binding domain) and virulence (insertion of amino acids in the cleavage site) were found to be positively selected in HA nucleotide sequences, in genetically unrelated lineages, suggesting parallel evolution for the HA gene of IA viruses in domestic birds. These results highlight that evolutionary consequences of bird host shifts would need to be further studied to understand the ecological and molecular mechanisms involved in the emergence of domestic bird-adapted viruses

Epidemiology of Q fever in dairy goat herds in the Netherlands

Between 2007 and 2009, the largest human Q fever epidemic ever described occurred in the Netherlands. The source was traced back to dairy goat farms, where abortion storms caused by Coxiella burnetii had been observed. Intervention measures included vaccination of dairy goats, followed by one-time culling of all pregnant animals from infected dairy goat herds in early 2010. These measures aimed to prevent further shedding of C. burnetii into the environment during the next kidding season, thus minimizing human exposure. Beginning in 2010, the number of human cases sharply decreased, suggesting that the intervention measures, including continued yearly vaccination of all dairy goat herds, were effective. One putative cause of the abortion storms in dairy goat herds was the intensive husbandry systems in which the goats were, and still are, kept. However, as this thesis shows, the abortion storms in Dutch dairy goat herds could not be fully simulated by demographic factors, such as herd size or reproductive patterns. Aspects of the pathogenesis in goats probably play and unknown but essential role in the observed abortion patterns. There are gaps in our current understanding of the drivers of Q fever abortion storms, and this may hamper the prevention of future problems on intensive goat farms and in humans living in their environment in a non-vaccination situation. Transmission via inhalation is considered the main mode of transmission for C. burnetii, but at the time of the Dutch epidemic, only a few published studies had actually demonstrated airborne C. burnetii. A method to detect C. burnetii DNA in airborne dust samples of size fractions that can be inhaled by humans is described in this thesis. With this method, C. burnetii DNA was indeed detected in airborne dust samples collected at three affected dairy goat farms. This finding supports the general assertion that airborne transmission is a likely route of exposure. As this thesis shows, vaccination reduces bacterial shedding by small ruminants. Both prevalence and bacterial load was reduced in the uterine fluid, vaginal mucus and milk of animals from vaccinated herds compared with animals from unvaccinated herds. These effects were most pronounced in animals during their first pregnancy. Results indicate that vaccination may reduce bacterial load in the environment and thus lessen human exposure to C. burnetii. Animals with a positive PCR in uterine fluid can be considered high risk animals, because they may shed massive amounts of bacteria during delivery. In a field setting, sampling of uterine fluid is not possible. To predict which animals are high risk animals, test characteristics of current tests for C. burnetii were evaluated for vaginal mucus (PCR), milk (PCR and ELISA), in recently infected unvaccinated herds. Due to poor test performance, identification and selective removal of high risk animals only (the test and cull strategy) to protect public health seems currently unfeasible. Because emergency vaccination of these animals is also not effective, the hazard of massive bacterial shedding during abortion or parturition can only be prevented by removal of all pregnant animals from recently infected naive (i.e. non vaccinated) herds

Epidemiology of Q fever in dairy goat herds in the Netherlands

Between 2007 and 2009, the largest human Q fever epidemic ever described occurred in the Netherlands. The source was traced back to dairy goat farms, where abortion storms caused by Coxiella burnetii had been observed. Intervention measures included vaccination of dairy goats, followed by one-time culling of all pregnant animals from infected dairy goat herds in early 2010. These measures aimed to prevent further shedding of C. burnetii into the environment during the next kidding season, thus minimizing human exposure. Beginning in 2010, the number of human cases sharply decreased, suggesting that the intervention measures, including continued yearly vaccination of all dairy goat herds, were effective. One putative cause of the abortion storms in dairy goat herds was the intensive husbandry systems in which the goats were, and still are, kept. However, as this thesis shows, the abortion storms in Dutch dairy goat herds could not be fully simulated by demographic factors, such as herd size or reproductive patterns. Aspects of the pathogenesis in goats probably play and unknown but essential role in the observed abortion patterns. There are gaps in our current understanding of the drivers of Q fever abortion storms, and this may hamper the prevention of future problems on intensive goat farms and in humans living in their environment in a non-vaccination situation. Transmission via inhalation is considered the main mode of transmission for C. burnetii, but at the time of the Dutch epidemic, only a few published studies had actually demonstrated airborne C. burnetii. A method to detect C. burnetii DNA in airborne dust samples of size fractions that can be inhaled by humans is described in this thesis. With this method, C. burnetii DNA was indeed detected in airborne dust samples collected at three affected dairy goat farms. This finding supports the general assertion that airborne transmission is a likely route of exposure. As this thesis shows, vaccination reduces bacterial shedding by small ruminants. Both prevalence and bacterial load was reduced in the uterine fluid, vaginal mucus and milk of animals from vaccinated herds compared with animals from unvaccinated herds. These effects were most pronounced in animals during their first pregnancy. Results indicate that vaccination may reduce bacterial load in the environment and thus lessen human exposure to C. burnetii. Animals with a positive PCR in uterine fluid can be considered high risk animals, because they may shed massive amounts of bacteria during delivery. In a field setting, sampling of uterine fluid is not possible. To predict which animals are high risk animals, test characteristics of current tests for C. burnetii were evaluated for vaginal mucus (PCR), milk (PCR and ELISA), in recently infected unvaccinated herds. Due to poor test performance, identification and selective removal of high risk animals only (the test and cull strategy) to protect public health seems currently unfeasible. Because emergency vaccination of these animals is also not effective, the hazard of massive bacterial shedding during abortion or parturition can only be prevented by removal of all pregnant animals from recently infected naive (i.e. non vaccinated) herds