-
FEMS Microbiology Reviews Sep 2020Wild birds interconnect all parts of the globe through annual cycles of migration with little respect for country or continental borders. Although wild birds are... (Review)
Review
Wild birds interconnect all parts of the globe through annual cycles of migration with little respect for country or continental borders. Although wild birds are reservoir hosts for a high diversity of gamma- and deltacoronaviruses, we have little understanding of the ecology or evolution of any of these viruses. In this review, we use genome sequence and ecological data to disentangle the evolution of coronaviruses in wild birds. Specifically, we explore host range at the levels of viral genus and species, and reveal the multi-host nature of many viral species, albeit with biases to certain types of avian host. We conclude that it is currently challenging to infer viral ecology due to major sampling and technical limitations, and suggest that improved assay performance across the breadth of gamma- and deltacoronaviruses, assay standardization, as well as better sequencing approaches, will improve both the repeatability and interpretation of results. Finally, we discuss cross-species virus transmission across both the wild bird - poultry interface as well as from birds to mammals. Clarifying the ecology and diversity in the wild bird reservoir has important ramifications for our ability to respond to the likely future emergence of coronaviruses in socioeconomically important animal species or human populations.
Topics: Animals; Animals, Wild; Birds; Coronavirus; Coronavirus Infections; Disease Reservoirs; Gammacoronavirus; Host Specificity
PubMed: 32672814
DOI: 10.1093/femsre/fuaa026 -
Mathematical Biosciences Nov 2017Leishmaniasis is a parasite disease transmitted by the bites of sandflies. Cutaneous leishmaniasis is the most common form of the disease and it is endemic in the...
Leishmaniasis is a parasite disease transmitted by the bites of sandflies. Cutaneous leishmaniasis is the most common form of the disease and it is endemic in the Americas. Around 70 animal species, including humans, have been found as natural reservoir hosts of leishmania parasites. Among the reservoirs, dogs are the most important ones due to their proximity to the human habitat. Infection by leishmaniasis does not invariably cause illness in the host, and it also can remain asymptomatic for a long period, specially in dogs. In this work we formulate a model to study the transmission of the disease among the vector, humans and dogs. Our main objective is to asses the impact of dogs as a reservoir as well as the impact of asymptomatic humans and dogs on the spread of leishmaniasis. For this end we calculate the Basic Reproduction Number of the disease and we carry out sensitivity analysis of this parameter with respect to the epidemiological and demographic parameters.
Topics: Animals; Asymptomatic Infections; Basic Reproduction Number; Disease Reservoirs; Dog Diseases; Dogs; Female; Humans; Insect Bites and Stings; Insect Vectors; Leishmaniasis, Cutaneous; Models, Biological; Psychodidae
PubMed: 28864398
DOI: 10.1016/j.mbs.2017.08.006 -
Current HIV/AIDS Reports Mar 2015The persistence of human immunodeficiency virus type 1 (HIV-1) in latent reservoirs is a major barrier to HIV cure. Reservoir establishment depends on low viral... (Review)
Review
The persistence of human immunodeficiency virus type 1 (HIV-1) in latent reservoirs is a major barrier to HIV cure. Reservoir establishment depends on low viral expression that may be related to provirus integration sites (IS). In vitro, in cell lines and primary T cells, latency is associated with specific IS through reduced viral expression mediated by transcriptional interference by host cellular promoters, reverse orientation, and the presence of specific epigenetic modifiers. In primary T cell models of latency, specific IS are associated with intracellular viral antigen expression that is not directly related to cell activation. In contrast, in patient CD4+ T cells, there is enrichment for IS in genes controlling cell cycle and survival and in some clonally expanded T cell subpopulations. Multiple insertion sites within some specific genes may suggest that integrated HIV can increase the host's T cell survival.
Topics: Disease Reservoirs; HIV Infections; HIV-1; Humans; Virus Integration; Virus Latency
PubMed: 25573791
DOI: 10.1007/s11904-014-0241-9 -
The Veterinary Record May 2022
Topics: Animals; Cattle; Cattle Diseases; Disease Reservoirs; Mustelidae; Mycobacterium bovis; Population Control; Tuberculosis, Bovine
PubMed: 35521882
DOI: 10.1002/vetr.1762 -
The Veterinary Record May 2022
Topics: Animals; Cattle; Cattle Diseases; Disease Reservoirs; Mustelidae; Mycobacterium bovis; Population Control; Tuberculosis, Bovine
PubMed: 35593565
DOI: 10.1002/vetr.1822 -
Biological Reviews of the Cambridge... Jun 2020Enteric illnesses remain the second largest source of communicable diseases worldwide, and wild birds are suspected sources for human infection. This has led to efforts... (Meta-Analysis)
Meta-Analysis Review
Enteric illnesses remain the second largest source of communicable diseases worldwide, and wild birds are suspected sources for human infection. This has led to efforts to reduce pathogen spillover through deterrence of wildlife and removal of wildlife habitat, particularly within farming systems, which can compromise conservation efforts and the ecosystem services wild birds provide. Further, Salmonella spp. are a significant cause of avian mortality, leading to additional conservation concerns. Despite numerous studies of enteric bacteria in wild birds and policies to discourage birds from food systems, we lack a comprehensive understanding of wild bird involvement in transmission of enteric bacteria to humans. Here, we propose a framework for understanding spillover of enteric pathogens from wild birds to humans, which includes pathogen acquisition, reservoir competence and bacterial shedding, contact with people and food, and pathogen survival in the environment. We place the literature into this framework to identify important knowledge gaps. Second, we conduct a meta-analysis of prevalence data for three human enteric pathogens, Campylobacter spp., E. coli, and Salmonella spp., in 431 North American breeding bird species. Our literature review revealed that only 3% of studies addressed the complete system of pathogen transmission. In our meta-analysis, we found a Campylobacter spp. prevalence of 27% across wild birds, while prevalence estimates of pathogenic E. coli (20%) and Salmonella spp. (6.4%) were lower. There was significant bias in which bird species have been tested, with most studies focusing on a small number of taxa that are common near people (e.g. European starlings Sturnus vulgaris and rock pigeons Columba livia) or commonly in contact with human waste (e.g. gulls). No pathogen prevalence data were available for 65% of North American breeding bird species, including many commonly in contact with humans (e.g. black-billed magpie Pica hudsonia and great blue heron Ardea herodias), and our metadata suggest that some under-studied species, taxonomic groups, and guilds may represent equivalent or greater risk to human infection than heavily studied species. We conclude that current data do not provide sufficient information to determine the likelihood of enteric pathogen spillover from wild birds to humans and thus preclude management solutions. The primary focus in the literature on pathogen prevalence likely overestimates the probability of enteric pathogen spillover from wild birds to humans because a pathogen must survive long enough at an infectious dose and be a strain that is able to colonize humans to cause infection. We propose that future research should focus on the large number of under-studied species commonly in contact with people and food production and demonstrate shedding of bacterial strains pathogenic to humans into the environment where people may contact them. Finally, studies assessing the duration and intensity of bacterial shedding and survival of bacteria in the environment in bird faeces will help provide crucial missing information necessary to calculate spillover probability. Addressing these essential knowledge gaps will support policy to reduce enteric pathogen spillover to humans and enhance bird conservation efforts that are currently undermined by unsupported fears of pathogen spillover from wild birds.
Topics: Animal Migration; Animals; Animals, Wild; Bacterial Infections; Bird Diseases; Birds; Disease Reservoirs; Humans; Livestock; Prevalence; Regression Analysis; Risk Factors; Virulence
PubMed: 32003106
DOI: 10.1111/brv.12581 -
Infection, Genetics and Evolution :... Jun 2021Listeria monocytogenes is a pathogen causing serious or mortal infections in human risk populations. Its infectivity is in part due to its ability to infect diverse...
Listeria monocytogenes is a pathogen causing serious or mortal infections in human risk populations. Its infectivity is in part due to its ability to infect diverse eukaryotic cells. Since several bacteria can enter into yeast cells, including Candida albicans, the aims of this work were to evaluate if L. monocytogenes was able to harbor, retaining its viability, within C. albicans cells and to evaluate the effect of temperature and an antibiotic as stressing factors in its rate of entry into yeast cells. Both microorganisms were co-incubated in BHI broth during 48 h and the entry of bacteria into yeast cells was evaluated at different times. Then, yeasts free of extracellular bacteria were obtained seeding samples of the co-culture on YGC agar, which contains chloramphenicol, to obtain extracellular bacteria-free yeasts. These extracellular bacteria free yeasts were used to search for bacterial DNA in total yeast DNA and to evaluate the viability of intra-yeast bacteria. Finally, the effect of temperature and of chloramphenicol as inducers of stress on the rate of bacterial entry into yeast cells were investigated. After co-culturing both microorganisms, wet mount optical microscopy showed the presence of moving bacteria within yeasts and transmission electron microscopy confirmed the presence of intra-yeast bacteria. PCR allowed to amplify L. monocytogenes iap gene in C. albicans total DNA obtained from yeasts free of extracellular bacteria. Moreover, the SYTO 9 green fluorescence observed in bacterial cells within vacuoles of yeasts suggests that intra-yeast bacteria remain viable. Furthermore, the entry of L. monocytogenes into yeasts cells was favored by the presence of stressing factors (chloramphenicol and temperature). Therefore, yeasts may be reservoirs of viable L. monocytogenes and might spread them to the following generations of yeasts.
Topics: Candida albicans; DNA, Bacterial; Disease Reservoirs; Listeria monocytogenes; Vacuoles
PubMed: 33639305
DOI: 10.1016/j.meegid.2021.104779 -
FEMS Microbiology Reviews Nov 2019Avian influenza viruses (AIVs) continue to impose a negative impact on animal and human health worldwide. In particular, the emergence of highly pathogenic AIV H5 and,... (Review)
Review
Avian influenza viruses (AIVs) continue to impose a negative impact on animal and human health worldwide. In particular, the emergence of highly pathogenic AIV H5 and, more recently, the emergence of low pathogenic AIV H7N9 have led to enormous socioeconomical losses in the poultry industry and resulted in fatal human infections. While H5N1 remains infamous, the number of zoonotic infections with H7N9 has far surpassed those attributed to H5. Despite the clear public health concerns posed by AIV H7, it is unclear why specifically this virus subtype became endemic in poultry and emerged in humans. In this review, we bring together data on global patterns of H7 circulation, evolution and emergence in humans. Specifically, we discuss data from the wild bird reservoir, expansion and epidemiology in poultry, significant increase in their zoonotic potential since 2013 and genesis of highly pathogenic H7. In addition, we analysed available sequence data from an evolutionary perspective, demonstrating patterns of introductions into distinct geographic regions and reassortment dynamics. The integration of all aspects is crucial in the optimisation of surveillance efforts in wild birds, poultry and humans, and we emphasise the need for a One Health approach in controlling emerging viruses such as AIV H7.
Topics: Animals; Disease Reservoirs; Epidemiological Monitoring; Humans; Influenza A Virus, H7N9 Subtype; Influenza in Birds; Influenza, Human; One Health; Phylogeny; Poultry; Zoonoses
PubMed: 31381759
DOI: 10.1093/femsre/fuz019 -
EcoHealth Sep 2022The relationship between humans, wildlife and disease transmission can be complex and context-dependent, and disease dynamics may be determined by idiosyncratic species....
The relationship between humans, wildlife and disease transmission can be complex and context-dependent, and disease dynamics may be determined by idiosyncratic species. Therefore, an outstanding question is how general is the finding that species with faster life histories are more probable hosts of zoonoses. Ecological knowledge on species, jointly with public health data, can provide relevant information on species that should be targeted for epidemiological surveillance or management. We investigated whether mammal species traits can be good indicators of zoonotic reservoir status in an intensified agricultural region of Argentina. We find support for a relationship between reservoir status and the pace of life syndrome, confirming that fast life histories can be a factor of zoonotic risk. Nonetheless, we observed that for certain zoonosis, reservoirs may display a slow pace of life, suggesting that idiosyncratic interactions can occur. We conclude that applying knowledge from the life history-disease relationship can contribute significantly to disease risk assessment. Such an approach may be especially valuable in the current context of environmental change and agricultural intensification.
Topics: Agriculture; Animals; Animals, Wild; Disease Reservoirs; Humans; Mammals; Public Health; Zoonoses
PubMed: 35841485
DOI: 10.1007/s10393-022-01608-5 -
Equine Veterinary Journal Mar 2018
Topics: Animals; Anti-Bacterial Agents; Bacteria; Bacterial Infections; Disease Reservoirs; Drug Resistance, Bacterial; Pets
PubMed: 29392804
DOI: 10.1111/evj.12785