scholarly journals Characterizing the phylogenetic specialism–generalism spectrum of mammal parasites

2018 ◽  
Vol 285 (1874) ◽  
pp. 20172613 ◽  
Author(s):  
A. W. Park ◽  
M. J. Farrell ◽  
J. P. Schmidt ◽  
S. Huang ◽  
T. A. Dallas ◽  
...  
Keyword(s):  
Host Species ◽  
Parasite Species ◽  
Close Contact ◽  
Discrete Groups ◽  
Phylogenetic Distance ◽  
Contact Transmission ◽  
Host Phylogeny ◽  
Differential Ability ◽  
Close Contact Transmission ◽  
Mammal Host

The distribution of parasites across mammalian hosts is complex and represents a differential ability or opportunity to infect different host species. Here, we take a macroecological approach to investigate factors influencing why some parasites show a tendency to infect species widely distributed in the host phylogeny (phylogenetic generalism) while others infect only closely related hosts. Using a database on over 1400 parasite species that have been documented to infect up to 69 terrestrial mammal host species, we characterize the phylogenetic generalism of parasites using standard effect sizes for three metrics: mean pairwise phylogenetic distance (PD), maximum PD and phylogenetic aggregation. We identify a trend towards phylogenetic specialism, though statistically host relatedness is most often equivalent to that expected from a random sample of host species. Bacteria and arthropod parasites are typically the most generalist, viruses and helminths exhibit intermediate generalism, and protozoa are on average the most specialist. While viruses and helminths have similar mean pairwise PD on average, the viruses exhibit higher variation as a group. Close-contact transmission is the transmission mode most associated with specialism. Most parasites exhibiting phylogenetic aggregation (associating with discrete groups of species dispersed across the host phylogeny) are helminths and viruses.

scholarly journals Simulating social distancing measures in household and close contact transmission of SARS-CoV-2

2020 ◽  
Vol 36 (5) ◽  
Author(s):  
Carlos Garcia Filho
Keyword(s):  
Close Contact ◽  
Contact Rate ◽  
Rate Reduction ◽  
Agent Based ◽  
Social Distancing ◽  
Infected People ◽  
Contact Transmission ◽  
Close Contact Transmission ◽  
The Relationship ◽  
Close Contacts

We sought to evaluate contact rate reduction goals for household and close contacts and to provide preventive recommendations during the coronavirus pandemic. We applied an agent-based model to simulate the transmission dynamics of SARS-CoV-2 within household or close contacts through a social network of 150 nodes. there is no great difference in total infected people within modifications in number of links per node for networks with average number of links per node greater than three. For six nodes, total infected people are 149.85; for five nodes, 148.97; and for four nodes, 141.57. On the other hand, for three nodes, total infected are 82.39, for two nodes, 13.95; and for one node, 2.96. This model indicates a possible pitfall if social distancing measures are not stepwise suspended and close surveillance of cases are not provided, since the relationship between average links per node and number of infected people seems to be s-shaped, and not linear.

Relative infection levels and taxonomic distances among the host species used by a parasite: insights into parasite specialization

Parasitology ◽  
2004 ◽  
Vol 130 (1) ◽  
pp. 109-115 ◽  
Author(s):  
R. POULIN
Keyword(s):  
Life Cycle ◽  
Freshwater Fish ◽  
Host Species ◽  
Parasite Species ◽  
Metazoan Parasites ◽  
Taxonomic Distance ◽  
Host Phylogeny ◽  
New Hosts ◽  
Surrogate Measure ◽  
Using Data

Parasites often exploit more than one host species at any stage in their life-cycle, but the extent to which these host species are used varies greatly. Parasites typically achieve their highest prevalence, intensity and/or abundance in one host species (the principal host), whereas infection levels in auxiliary hosts range from relatively high to very low. The present study examines what influences the distribution of parasite individuals among their different host species, using metazoan parasites that use freshwater fish as their definitive or only host. Specifically, I test the hypothesis that differences in relative infection levels by a parasite among its auxiliary hosts are proportional to the taxonomic distance between the respective auxiliary hosts and the parasite's principal host. Taxonomic distance among hosts is a surrogate measure of their similarity in terms of ecology, physiology and immunology. Using data on 29 parasite species and 6 fish communities, for a total of 47 parasite-locality combinations, it was found that taxonomic distance between the auxiliary hosts and the principal host had no real influence on infection levels in auxiliary hosts, measured as either prevalence, intensity or abundance. The analysis revealed differences in the degree of specialization among major groups of parasites: in terms of abundance or intensity, auxiliary hosts were less important for cestodes than for nematodes and copepods. The lack of an effect of taxonomic distance may indicate that ecological similarity among host species, arising from convergence and not from relatedness, is more important than host phylogeny or taxonomy. Although the results are based on a limited number of parasite taxa, they suggest that parasites may be opportunistic in their colonization of new hosts, and not severely constrained by evolutionary baggage.

scholarly journals VAKSINASI MASAL COVID-19 DI PELABUHAN LEMBAR LOMBOK BARAT

2021 ◽  
Vol 5 (1) ◽  
pp. 404
Author(s):  
Desi Rofita ◽  
Evi Diliana Rospia ◽  
Dwi Kartika Cahyaningtyas ◽  
Catur Esty Pamungkas ◽  
Aulia Amini ◽  
...  
Keyword(s):  
World Health Organization ◽  
Close Contact ◽  
Herd Immunity ◽  
The Elderly ◽  
Health Problems ◽  
Mass Vaccination ◽  
World Health ◽  
Contact Transmission ◽  
Health Organization ◽  
Close Contact Transmission

ABSTRAKWHO (World  Health  Organization) secara  resmi  mendeklarasikan  virus  corona (Covid-19)  sebagai  pandemi. Virus Covid-19 menyebabkan gejala seperti demam dan batuk, dan kebanyakan bisa sembuh dalam beberapa minggu. Tapi bagi sebagian orang yang berisiko tinggi (kelompok lanjut  usia  dan  orang  dengan masalah  kesehatan  menahun, seperti  penyakit  jantung,  tekanan darah  tinggi,  atau diabetes), virus corona dapat menyebabkan masalah kesehatan yang serius. Ada dua  jalur  utama  penularan COVID-19, yakni penularan droplet pernapasan dan penularan kontak dekat. Dalam rangka penanggulangan pandemi COVID-19 tidak hanya dilaksanakan dari sisi penerapan protokol kesehatan, namun juga intervensi dengan vaksinasi sebagai bagian dari upaya pencegahan dan Pengendalian COVID-19. Kegiatan vaksinasi masal ini bertujuan agar dapat terbentuk herd immunity (kekebalan kelompok) dan berkurangnya angka kematian akibat COVID-19 pada masyarakat.Jenis vaksin yang digunakan pada kegiatan vaksinasi masal ini adalah Moderna. Jumlah responden yang mengikuti kegiatan ini sebanyak 1.581 orang. Hasil pengabdian didapatkan bahwa jumlah yang melakukan vaksinasi sebanyak 1.581 orang yang terdiri remaja sebanyak 60 orang dewasa sebanyak 1497 orang dan lansia sebanyak 24 orang, diberikan vaksin sebanyak 1.536 orang, ditunda sebanyak 45 orang. Kata kunci: vaksinasi; covid-19; komunitas. ABSTRACTWHO (World Health Organization) has officially declared the coronavirus (Covid-19) as a pandemic. The Covid-19 virus causes symptoms such as fever and cough, and most recover within a few weeks. But for some people who are at high risk (the elderly and people with chronic health problems, such as heart disease, high blood pressure, or diabetes), the coronavirus can cause serious health problems. There are two main routes of transmission of COVID-19, namely respiratory droplet transmission and close contact transmission. In the context of dealing with the COVID-19 pandemic, it is not only implemented in terms of implementing health protocols but also interventions with vaccinations as part of efforts to prevent and control COVID-19. This mass vaccination activity aims to form herd immunity and reduce the mortality rate due to COVID-19 in the community. The type of vaccine used in this mass vaccination activity is Moderna. The number of respondents who participated in this activity was 1,581 people. The results of the service found that the number of people who registered for Pcare was 1,581 people, consisting of 60 teenagers, 1497 adults, and 24 elderly people, 1,536 people were given the vaccine, 45 people were delayed. Keywords: vaccination; covid-19; community. 

Age-prevalence and household clustering ofStrongyloides stercoralisinfection in Jamaica

Parasitology ◽  
1995 ◽  
Vol 110 (1) ◽  
pp. 97-102 ◽  
Author(s):  
J. F. Lindo ◽  
R. D. Robinson ◽  
S. I. Terry ◽  
P. Vogel ◽  
A. A. Gam ◽  
...  
Keyword(s):  
Close Contact ◽  
Spatial Separation ◽  
Strongyloides Stercoralis ◽  
Stool Examination ◽  
Place Of Residence ◽  
General Study ◽  
Reference Case ◽  
Contact Transmission ◽  
Study Population ◽  
Close Contact Transmission

The epidemiology ofStrongyloides stercoraliswas studied in families of clinical (reference) cases and their neighbours at endemic foci in Jamaica. Thirteen foci were studied based on the place of residence of a reference case. For each household of a reference case, the 4 most proximal neighbourhood households (spatial controls) were included in the study. Out of 312 persons contacted 244 were followed up using questionnaires, stool examination and serology. Prevalence of infection based on stool examination was 3·5% and on ELISA 24·2%. Prevalence increased with age but was not related to gender. Reference cases were significantly older than the general study population. The prevalence of infection based on both serology and stool examination was significantly higher in reference than in neighbouring households (the reference cases, themselves, were not included in the analysis). Furthermore, prevalence of infection was highest among persons who shared a bedroom with a reference case and decreased significantly with increasing spatial separation. This is indicative of close contact transmission which has not been previously shown for a geohelminth, but which is common among microparasites.

scholarly journals Phylosymbiosis across Deeply Diverging Lineages of Omnivorous Cockroaches (Order Blattodea)

2020 ◽  
Vol 86 (7) ◽  
Author(s):  
Kara A. Tinker ◽  
Elizabeth A. Ottesen
Keyword(s):  
Gut Microbiota ◽  
Significant Role ◽  
Gut Microbiome ◽  
Host Species ◽  
Evolutionary Divergence ◽  
Phylogenetic Distance ◽  
Evolutionary Time ◽  
Microbiome Composition ◽  
Ancient Lineage ◽  
Host Phylogeny

ABSTRACT The gut microbiome is shaped by both host diet and host phylogeny. However, separating the relative influence of these two factors over long periods of evolutionary time is often difficult. We conducted a 16S rRNA gene amplicon-based survey of the gut microbiome from 237 individuals and 19 species of omnivorous cockroaches from the order Blattodea. The order Blattodea represents an ancient lineage of insects that emerged over 300 million years ago, have a diverse gut microbiota, and have a typically gregarious lifestyle. All cockroaches shared a broadly similar gut microbiota, with 66 microbial families present across all species and 13 present in every individual examined. Although our network analysis of the cockroach gut microbiome showed a large amount of connectivity, we demonstrated that gut microbiota cluster strongly by host species. We conducted follow-up tests to determine if cockroaches exhibit phylosymbiosis, or the tendency of host-associated microbial communities to parallel the phylogeny of related host species. Across the full data set, gut microbial community similarity was not found to correlate with host phylogenetic distance. However, a weak but significant phylosymbiotic signature was observed using the matching cluster metric, which allows for localized changes within a phylogenetic tree that are more likely to occur over long evolutionary distances. This finding suggests that host phylogeny plays a large role in structuring the cockroach gut microbiome over shorter evolutionary distances and a weak but significant role in shaping the gut microbiome over extended periods of evolutionary time. IMPORTANCE The gut microbiome plays a key role in host health. Therefore, it is important to understand the evolution of the gut microbiota and how it impacts, and is impacted by, host evolution. In this study, we explore the relationship between host phylogeny and gut microbiome composition in omnivorous, gregarious cockroaches within the Blattodea order, an ancient lineage that spans 300 million years of evolutionary divergence. We demonstrate a strong relationship between host species identity and gut microbiome composition and found a weaker but significant role for host phylogeny in determining microbiome similarity over extended periods of evolutionary time. This study advances our understanding of the role of host phylogeny in shaping the gut microbiome over different evolutionary distances.

scholarly journals Factors Affecting COVID-19 Transmission and Modelling of Close Contact Tracing Strategies

2021 ◽  
Author(s):  
Shahram Yazdani ◽  
Majid Heydari ◽  
Zeynab Foroughi ◽  
Hadi Jabali
Keyword(s):  
Risk Score ◽  
Close Contact ◽  
Transmission Risk ◽  
Contact Tracing ◽  
Rapid Review ◽  
Risk Scores ◽  
Virus Shedding ◽  
Factors Affecting ◽  
Contact Transmission ◽  
Close Contact Transmission

Background: Close contact tracing is an essential measure that countries are applying to combat the epidemic of COVID-19. The purpose of contact tracing is to rapidly identify potentially infected individuals and prevent further spread of the disease. In this study, based on the factors affecting the COVID-19 transmission, a scoring protocol is provided for close contact tracing. Methods: First, the factors affecting the COVID-19 transmission in close contacts were identified by a rapid review of the literature. Data were gathered by searching the Embase, PubMed, Google Scholar, and Scopus databases. Then, by formulating and scoring the identified factors with two sessions of the expert panel, close contact transmission risk score determined, and a protocol for contacts tracing was designed. Results: Close contact transmission risk depends on the contact environment characteristics, the infectivity (virus shedding) of the sentinel case, and contact characteristics. Based on these factors, the close contact transmission risk score and contact tracing protocol were prepared.   Conclusion: The close contact transmission risk scores will provide the ability to contact classifications and developing specific tracing strategies for them. Given that there are not any specific treatments for COVID-19 and lack of universal vaccination, applying nonpharmaceutical measures such as contact tracing along with physical distancing is very crucial. Therefore, we recommended this model to the evaluation of exposure risk and contact tracing.

scholarly journals Dynamics of infectious disease transmission by inhalable respiratory droplets

2010 ◽  
Vol 7 (50) ◽  
pp. 1355-1366 ◽  
Author(s):  
Nikolaos I. Stilianakis ◽  
Yannis Drossinos
Keyword(s):  
Disease Transmission ◽  
Close Contact ◽  
Droplet Diameter ◽  
Droplet Dynamics ◽  
Contact Rates ◽  
Transmission Modes ◽  
Contact Transmission ◽  
Close Contact Transmission ◽  
Respiratory Droplets

Transmission of respiratory infectious diseases in humans, for instance influenza, occurs by several modes. Respiratory droplets provide a vector of transmission of an infectious pathogen that may contribute to different transmission modes. An epidemiological model incorporating the dynamics of inhalable respiratory droplets is developed to assess their relevance in the infectious process. Inhalable respiratory droplets are divided into respirable droplets, with droplet diameter less than 10 µm, and inspirable droplets, with diameter in the range 10–100 µm: both droplet classes may be inhaled or settle. Droplet dynamics is determined by their physical properties (size), whereas population dynamics is determined by, among other parameters, the pathogen infectivity and the host contact rates. Three model influenza epidemic scenarios, mediated by different airborne or settled droplet classes, are analysed. The scenarios are distinguished by the characteristic times associated with breathing at contact and with hand-to-face contact. The scenarios suggest that airborne transmission, mediated by respirable droplets, provides the dominant transmission mode in middle and long-term epidemics, whereas inspirable droplets, be they airborne or settled, characterize short-term epidemics with high attack rates. The model neglects close-contact transmission by droplet sprays (direct projection onto facial mucous membranes), retaining close-contact transmission by inspirable droplets.

Sign in / Sign up

Export Citation Format

Share Document