chunk_id string | chunk string |
|---|---|
8e450be66b86a16854c745fc0836720a_8 | of the viral virulence (pathogenicity) and the host immunity. Some researchers' opinions on H7N9 avian influenza virus were incorrect and/or inadequate. They mainly focused on influenza viruses and worried about viral mutations, viral pathogenicity, viral adaptation, and transmission. They overestimated the negative pa... |
8e450be66b86a16854c745fc0836720a_9 | prefectural-level city, and county) centers for disease control and prevention all over China (24) . Second, physicians and nurses in China were prepared and knowledgeable of influenza virus infections. Third, samples from patients with suspected influenza virus infections were collected and sent to the local and natio... |
8e450be66b86a16854c745fc0836720a_10 | the live poultry markets of the involved epidemic region quickly. Sixth, patients were isolated and treated timely in hospitals, 74% (1251/1689) of those close contacts of H7N9 influenza patients were monitored and observed. Thus, H7N9 influenza A virus could not spread to a bigger population (24) . Last but not least,... |
8e450be66b86a16854c745fc0836720a_11 | infection might only be the tip of the iceberg. Aside from one laboratory confirmed asymptotic case of H7N9 influenza A virus infection in Beijing (22), there were probably many undetected mild or asymptotic cases of influenza A H7N9 infection. The reason is that most people usually think a common cold is a very common... |
8e450be66b86a16854c745fc0836720a_12 | Nowadays, we travel faster, and we travel more frequently and globally, and we have more complicated social activities and lifestyles, thereby increasing the chances of viral mutation; and we realize that influenza viruses are even easier to reassort, recombine, and mutate in nature than many other RNA viruses. However... |
8e450be66b86a16854c745fc0836720a_13 | infections of all influenza virus strains, or we could produce some very effective anti-influenza virus drugs; then influenza would not be a problem anymore. We should learn lessons from the mistakes we made in the past. It is reasonable and necessary to be cautious about influenza viruses, but overreactions or catastr... |
8e450be66b86a16854c745fc0836720a_14 | Liting Song: conception of manuscript, drafting of manuscript, critical revision of manuscript, and final approval of manuscript.
The author would like to recognize the contributions of the reviewers and editors of this manuscript for their corrections and editing, and Dr. Emanuel Goldman for correcting errors related... |
78a3b3afd15732b8a71c3ed7797ad476_0 | Ebola Virus Maintenance: If Not (Only) Bats, What Else?
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6213544/
SHA: f16da7cf7a952fb981dfc0d77280aac9c3ab933a
Authors: Caron, Alexandre; Bourgarel, Mathieu; Cappelle, Julien; Liégeois, Florian; De Nys, Hélène M.; Roger, François
Date: 2018-10-09
DOI: 10.3390/v10100549
Li... |
78a3b3afd15732b8a71c3ed7797ad476_1 | Abstract: The maintenance mechanisms of ebolaviruses in African forest ecosystems are still unknown, but indirect evidences point at the involvement of some bat species. Despite intense research, the main bat-maintenance hypothesis has not been confirmed yet. The alternative hypotheses of a non-bat maintenance host or ... |
78a3b3afd15732b8a71c3ed7797ad476_2 | that can lead to bat exposure and infection to ebolaviruses. In contrast to the capacity of bats to transmit ebolaviruses and other pathogens to many hosts, our results indicate that only a limited number of hosts and pathways can lead to the transmission of ebolaviruses to bats, and that the alternative maintenance ho... |
78a3b3afd15732b8a71c3ed7797ad476_3 | Text: Ebolaviruses (EBVs), according to Kuhn et al. classification [1] ) are single-strand RNA filoviruses that can induce a high mortality in some hosts, including apes and humans [2, 3] . The different ebolaviruses have caused localised but dramatic human outbreaks, mainly in Central Africa, in the last 40 years. The... |
78a3b3afd15732b8a71c3ed7797ad476_4 | Disentangling the complexity of maintenance hosts or communities in multi-host systems at the wildlife/livestock/human interface is a difficult task [16] [17] [18] . The maintenance of EBV in equatorial forests is yet to be understood. Some mammal species played a major role in triggering human outbreaks: apes such as ... |
78a3b3afd15732b8a71c3ed7797ad476_5 | EBOV susceptibility and exposure (tested by virology, serology and/or PCR) of many other potential forest hosts, including invertebrates, birds, bats, monkeys, rodents, and other small mammals, have been tested in the field or experimentally with an interestingly large amount of negative results (e.g., [12, [21] [22] [... |
78a3b3afd15732b8a71c3ed7797ad476_6 | Today, African bats are considered by many as the best candidates for acting as maintenance hosts for EBOV. Partial vRNA was sequenced from living specimens of three different bat species in Central Africa [23] , and antibodies against ebolavirus antigen have been detected in 9 bat species (8 frugivorous and 1 insectiv... |
78a3b3afd15732b8a71c3ed7797ad476_7 | despite thousands of individuals tested [14, [23] [24] [25] 28, 34, 35] . Given the current knowledge, the main hypotheses for EBOV maintenance are a single bat species as Rousettus aegyptiacus is considered the maintenance host for Marburg virus ( Figure 1A1 ); or a network of interacting bat species creating a mainte... |
78a3b3afd15732b8a71c3ed7797ad476_8 | The bat system is complex. First, for its diversity: globally, they represent over 20% of the mammal diversity, forming the second largest mammalian order after rodents, and Africa hosts 317 known living species, 25% of the global bat diversity [36] . Secondly, bats have exceptional lifestyles that have already been re... |
78a3b3afd15732b8a71c3ed7797ad476_9 | negative results (e.g., [12, [21] [22] [23] [24] [25] [26] ). A few monkey and bat individuals serologically positive to EBV antigen represent the only exceptions [12] . |
78a3b3afd15732b8a71c3ed7797ad476_10 | Potential maintenance mechanisms of ebolaviruses in wildlife, according to current knowledge. Circles (plain or dotted) indicate a maintenance function play by the host(s); arrows represent infectious transmission pathways between hosts. Humans, non-human primates, and duikers are examples of known non-maintenance host... |
78a3b3afd15732b8a71c3ed7797ad476_11 | this is logically the most investigated hypothesis given the available data, and represents the maintenance mechanism for another filovirus, the Marburg virus, as currently understood. (A2) Several bat species are needed to create a maintenance community for Zaire ebolavirus (EBOV); each bat species cannot complete EBO... |
78a3b3afd15732b8a71c3ed7797ad476_12 | this host towards bats that are reviewed here (red arrows). |
78a3b3afd15732b8a71c3ed7797ad476_13 | Proving that a bat species maintains EBOV (e.g., [44, 45] ), or that interconnected populations of different bat species create the cradle for EBOV maintenance in a specific ecosystem, is a difficult task. Finding a live virus in a healthy bat specimen would constitute a great step in proving that this particular speci... |
78a3b3afd15732b8a71c3ed7797ad476_14 | The gaps in knowledge concerning the maintenance of EBOV and other EBV are therefore still significant. Available data indicates a systematic but weak signal in some bat species, a pattern in line with the main bat maintenance hypotheses, but not excluding as well alternative hypotheses as presented in Figure 1B ,C. If... |
78a3b3afd15732b8a71c3ed7797ad476_15 | still a possibility that bats are not part of or that non-bat species are involved in the EBOV maintenance system and alternative scenarios should be considered and explored ( Figure 1 ) [46] . These scenarios should be investigated, when possible, alongside bat-centred protocols, to confirm or invalidate the case for ... |
78a3b3afd15732b8a71c3ed7797ad476_16 | When a probability P is difficult or impossible to estimate, it is sometimes easier to estimate its inverse probability (1-P), the probability that it does not happen. It would be tedious to quantitatively estimate probabilities in the case of ebolavirus maintenance given the current lack of information, but trying to ... |
78a3b3afd15732b8a71c3ed7797ad476_17 | Here, we consider the scenario presented in Figure 1B ,C, namely, that bats are not the maintenance host for EBOV or that bat species are involved with alternative host(s) in the EBOV maintenance community. Current data and knowledge support both scenarios. Some bats are sometimes in contact with the virus and experien... |
78a3b3afd15732b8a71c3ed7797ad476_18 | environment). The search for alternative maintenance hosts for EBOV should, therefore, concentrate on hosts that can transmit the virus to bats. In other words, any host that could not transmit the virus to bats would be ineligible to be a maintenance host for EBOV. This holds for any host found exposed to EBOV (e.g., ... |
78a3b3afd15732b8a71c3ed7797ad476_19 | The ecology of most African bat species is largely unknown. It can still be summarised as follows: roosting in trees (hanging or in holes) or caves, flying, eating insects while flying (insectivorous bats)/eating fruits in trees (fruit bat), flying back and roosting in trees or caves; with biannual long-range migration... |
78a3b3afd15732b8a71c3ed7797ad476_20 | ) to infect bats seems to be much more limited. For example, bats seldom use the ground floor: transmission routes requiring direct contact or environmental transmission on the ground do not expose bats. In other terms, direct contacts with strictly ground-dwelling animals would be very unlikely. Four habitat types str... |
78a3b3afd15732b8a71c3ed7797ad476_21 | Firstly, EBOV transmission to bats could occur through aerosol transmission in all four habitats. This means that the maintenance host would release, in bats' airspace, enough EBOV to contaminate bats. In theory, this would be possible in most bat environments, but we have discarded open-air transmission (e.g., in-flig... |
78a3b3afd15732b8a71c3ed7797ad476_22 | route might thus be possible. However, as bats tend to roost aggregated in groups and sometimes in large colonies, the ambient air may be saturated by bats' aerosols, rather than an alternative host. Air screening could be attempted in bat habitats but experimental aerosol transmission trials from alternative hosts to ... |
78a3b3afd15732b8a71c3ed7797ad476_23 | Bats are exposed to ectoparasitism [61] . If the biting invertebrate has previously bitten the alternative maintenance host, it could, in principle, infect bats. Hematophagous insects have been screened for EBOV during or after outbreaks with no conclusive results [26, 75] . However, absence of exposure during an outbr... |
78a3b3afd15732b8a71c3ed7797ad476_24 | [62, 63] . Bat flies appear to be highly bat-specific, adapted to their lifestyle [77] [78] [79] [80] and are involved in the transmission of pathogens [64] . However, this specificity would preclude interspecies pathogen transmission. Ectoparasitism provides a potential solid source of indirect contacts between the al... |
78a3b3afd15732b8a71c3ed7797ad476_25 | Insectivorous bats feed on insects that could be a source of EBOV [61] . This food-borne route has been little investigated as well. A recent study pointed out the role of insect-specific viruses in the evolution of numerous viral families, including mononegaviruses, which infect vertebrates [81] . There is a possibili... |
78a3b3afd15732b8a71c3ed7797ad476_26 | that the population dynamics of mayflies may act as a driver of EBOV emergence in mammals and humans [46] . Insectivorous bat diet analysis could, therefore, indicate the relative proportion of hematophagous insect fed upon by bats and their identity, in order to subsequently target these insect species for sampling. |
78a3b3afd15732b8a71c3ed7797ad476_27 | The EBOV maintenance host could shed viable viruses in the environment where bats could get infected by environmental exposure. The most likely habitats where this can happen are tree canopies and holes, and cave roofs/walls used only by a fraction of hosts inhabiting forests. The probability of infection will be depen... |
78a3b3afd15732b8a71c3ed7797ad476_28 | One particular mechanism that has been put forward in the literature is the fruit-borne route concerning frugivorous bats in the tree canopy. The availability of fruits attracts fruit-eating animals, including birds, tree-dwelling mammals, and invertebrates. This behaviour can create a network of contacts between hosts... |
78a3b3afd15732b8a71c3ed7797ad476_29 | from human urine and saliva [51] , hence, could also be transmitted from faeces, urine, and saliva from other species. This transmission route is therefore possible, but restrained to the fauna feeding at the same height as bats (or, technically, above). The hypothesis of fruits soiled with infected body fluids falling... |
78a3b3afd15732b8a71c3ed7797ad476_30 | A relation between river systems and EBOV outbreaks has been suggested in Central Africa, with tributaries influencing the spatial distribution of cases [84] . If river systems can harbour specific biotic communities with potential alternative hosts, such as water-dependent vectors [46] , they can also represent, in re... |
78a3b3afd15732b8a71c3ed7797ad476_31 | the shores, would not favour such a transmission route a priori. |
78a3b3afd15732b8a71c3ed7797ad476_32 | Tree and cave roosts could expose hanging and resting bats to direct contact with a potential maintenance host. However, as a first observation, the upside-down vertical position of bat roosting does not really favour disease transmission from an alternative host. For bat species roosting in tree-holes, the situation c... |
78a3b3afd15732b8a71c3ed7797ad476_33 | infectious contact from bats to other organisms [53] . Novel technologies, such as camera traps equipped with nocturnal vision, could provide opportunities for more research on this topic. |
78a3b3afd15732b8a71c3ed7797ad476_34 | As the ecology of most Africa bats is unknown, other opportunities exposing bat to potential maintenance hosts may be discovered in the future. For example, some bat species feed on fish [86] and, more recently, using stable isotopes of carbon and nitrogen as dietary tracers, it was demonstrated that a bat species, Nyc... |
78a3b3afd15732b8a71c3ed7797ad476_35 | Considering the scenario B and C in Figure 1 , that bats are not the maintenance hosts of EBOV or that they are not the only host involved in the maintenance of EBOV, helps in focusing EBOV research protocols on a reduced range of potential transmission routes and potential alternative hosts interacting with bats in th... |
78a3b3afd15732b8a71c3ed7797ad476_36 | observation of this limited number of hosts calls for testing them, even if only to exclude them from the list of hypotheses and strengthen the main hypothesis. As warned above, the EBOV multi-host maintenance system could include a complex network of interacting bat species ( Figure 1A2 ) and to proceed by elimination... |
78a3b3afd15732b8a71c3ed7797ad476_37 | In order for these protocols to be efficient and well designed, insights from behavioural ecology, plant phenology, and molecular biology (amongst other disciplines) will be necessary. Integrated approaches to health have been proposed recently and, in EBOV ecology, they should promote the integration of ecological sci... |
78a3b3afd15732b8a71c3ed7797ad476_38 | ecologically driven hypotheses. This is what is currently done for bats following the main maintenance hypothesis (e.g., [30] ), but not often for alternative hosts. Experimental trials should also concentrate on the environmental conditions occurring in bat-specific habitats, which can be very different from human out... |
78a3b3afd15732b8a71c3ed7797ad476_39 | The transmission routes towards bats represent interhost contacts of unknown intensity and frequency, and it would be difficult to compare their relative importance. However, one can prioritize some transmission routes based on the current knowledge. The insect food-borne and vector-borne routes of transmission need, s... |
78a3b3afd15732b8a71c3ed7797ad476_40 | bats, in caves or at canopy level, and not at ground level where bats may not occur. Studying host interaction networks at fruit feeding sites is also an interesting avenue to explore direct, environmental, and fruit-borne routes of transmission. Behavioural ecology could inform and help targeting protocols. Chimpanzee... |
78a3b3afd15732b8a71c3ed7797ad476_41 | Under field reality, and especially in rainforests, this list of protocols will need a carefully designed programme to be successful, rooted in interdisciplinarity. As bats, and especially those species that have been exposed to ebolaviruses, are the entry point of most of these alternative hypotheses (i.e., alternativ... |
78a3b3afd15732b8a71c3ed7797ad476_42 | implemented, and a biological search for antibodies or antigens can be implemented. Combining protocols to test the main and alternative hypotheses could provide cost-effective and synergetic options. |
78a3b3afd15732b8a71c3ed7797ad476_43 | To conclude, alternative hypotheses presented here should be explored alongside efforts to confirm bat species as maintenance hosts for EBOV. The ecology of those bat species already known to be exposed should be used to design protocols in order to target relevant alternative maintenance hosts. Given the number of spe... |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.