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Horizontal transmission

Horizontal transmission, also known as lateral transmission, is the transfer of infectious agents, symbionts, genetic material, or other biological entities between individuals or organisms not in a parent-offspring relationship, typically within the same generation; this contrasts with vertical transmission from parents to offspring during reproduction.^[1]^[2] In the context of infectious diseases, it refers to the spread of pathogens such as viruses, bacteria, fungi, or parasites from one individual to another. This mode is fundamental to epidemiology, enabling rapid dissemination through populations via direct or indirect contact, vectors, or environmental reservoirs.^[1]^[3] The concept extends beyond pathogens to include microbiome dynamics, horizontal gene transfer, and even cultural trait propagation in human societies. Horizontal transmission can occur through several distinct modes, broadly categorized as direct and indirect. Direct transmission involves immediate transfer between individuals, often via physical contact, respiratory droplets from coughing or sneezing, sexual activity, or fecal-oral routes through contaminated food or water; examples include the airborne spread of measles virus or the sexual transmission of HIV.^[2]^[1] Indirect transmission, on the other hand, relies on intermediaries such as fomites (inanimate objects like doorknobs), biological vectors (e.g., mosquitoes transmitting dengue virus or aphids spreading cucumber mosaic virus), or mechanical vectors (e.g., houseflies carrying bacteria on their bodies).^[2]^[1] These pathways are prevalent in both human and animal populations, with respiratory and vector-borne routes being particularly significant for global disease burdens like influenza, malaria, and Lyme disease.^[2] The importance of horizontal transmission lies in its role in sustaining epidemics and facilitating zoonotic spillover, where pathogens jump from animals to humans, as seen in emerging infections.^[1] Effective control measures, such as hand hygiene, vaccination, vector management, and sanitation, target these transmission routes to interrupt pathogen cycles and reduce incidence.^[2]

Definition and Fundamentals

Core Definition

Horizontal transmission refers to the non-parental transfer of genetic material, traits, infections, or cultural elements between individuals of the same generation or unrelated lineages, in contrast to vertical transmission from parent to offspring.^[4]^[5] This process is characterized by direct modes, such as physical contact or social interactions, and indirect modes, including transmission via vectors, environmental reservoirs, or airborne routes, enabling spread decoupled from reproductive inheritance patterns.^[4] The term horizontal transmission originated in microbiology during the mid-20th century to describe bacterial gene exchange mechanisms like conjugation, transformation, and transduction, and was later generalized to encompass pathogen spread and symbiont acquisition. The concept is applied analogously in cultural evolution to describe the diffusion of traits.^[6]^[7]^[5] Fundamental modes of horizontal transmission include contact-based exchange, airborne dispersal, vector-mediated delivery, and environmental uptake, each facilitating non-generational dissemination across biological systems.

Comparison to Vertical Transmission

Vertical transmission refers to the direct transfer of genetic elements, pathogens, or symbionts from parent to offspring, primarily through mechanisms such as gametes, the placenta in mammals, or nursing via milk or colostrum.^[8] This mode ensures that the transmitted entity is inherited along the familial lineage, providing a stable mechanism for persistence across generations.^[8] In contrast, horizontal transmission involves the transfer between non-parent-offspring individuals, typically within the same generation, allowing for broader dissemination independent of reproductive cycles.^[3] A key functional difference lies in their scope: horizontal transmission enables rapid proliferation across diverse populations without reliance on host reproduction, while vertical transmission is inherently generational and often obligate, tying the entity's survival to the host's reproductive success.^[9] From an evolutionary perspective, horizontal transmission offers advantages in promoting genetic diversity and accelerating adaptation by facilitating the quick acquisition and spread of beneficial traits, such as novel genes that enhance fitness in changing environments.^[10] However, this mode can introduce variability that risks genomic instability if incompatible elements are acquired.^[10] Vertical transmission, conversely, prioritizes fidelity by passing tested and compatible elements directly to offspring, reducing the chance of deleterious integrations and ensuring symbiont-host compatibility, though it constrains variability and slows adaptive responses compared to horizontal routes.^[8] These trade-offs highlight how horizontal transmission supports dynamic population-level changes, whereas vertical transmission fosters long-term stability within lineages.^[10] Hybrid transmission modes, though rare, illustrate overlaps between the two strategies, such as transovarial transmission in insects where entities are passed vertically from female to offspring via infected eggs, potentially enabling subsequent horizontal spread through vector behavior in later life stages.^[11] This mixed approach combines the assured inheritance of vertical transfer with the expansive potential of horizontal dissemination, though it remains exceptional in most biological systems.^[11]

Biological Mechanisms

Pathogen and Parasite Transmission

Horizontal transmission enables pathogens and parasites to spread between hosts within the same generation, primarily through direct and indirect contact mechanisms that facilitate rapid dissemination in populations. Direct contact transmission occurs via physical interactions, such as skin-to-skin contact during sexual intercourse, which is the primary mode for sexually transmitted infections like human immunodeficiency virus (HIV) and gonorrhea. Indirect transmission involves intermediaries, including fomites—contaminated surfaces or objects—or vectors like water sources harboring pathogens such as Vibrio cholerae in cholera outbreaks. Aerosol transmission, involving respiratory droplets or smaller airborne particles, is characteristic of viruses like influenza and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), allowing spread through coughing, sneezing, or talking in close proximity.^[12]^[13]^[14] Parasites also rely on horizontal routes for propagation, often exploiting environmental or vector-mediated pathways. In malaria, caused by Plasmodium species, horizontal transmission occurs exclusively through the bite of female Anopheles mosquitoes, which acquire the parasite from an infected human and inject sporozoites into a new host during a blood meal. Soil-transmitted helminths, including Ascaris lumbricoides and hookworms like Necator americanus, spread horizontally when eggs or larvae in human feces contaminate soil, leading to infection via ingestion of contaminated food or direct skin penetration in areas with poor sanitation. These modes underscore the role of environmental factors in amplifying parasite distribution across host populations.^[15]^[16]^[17] Pathogen persistence within hosts, essential for horizontal spread, is bolstered by sophisticated immune evasion strategies that allow infectious agents to avoid clearance and maintain transmissibility. For instance, Plasmodium falciparum employs antigenic variation of surface proteins like PfEMP1 to evade adaptive immunity, enabling chronic infections that sustain mosquito transmission cycles. Bacterial pathogens such as Neisseria gonorrhoeae modulate host innate immune responses by inhibiting complement activation and cytokine signaling, facilitating asymptomatic carriage and onward sexual transmission. These tactics ensure the pathogen remains viable in the host long enough to contact new individuals, highlighting the evolutionary pressure for immune subversion in horizontally transmitted agents.^[18]^[19]^[20]

Symbiont and Microbiome Transmission

Horizontal transmission of symbionts occurs through environmental acquisition, where hosts obtain microbial partners from surrounding habitats such as soil, water, or food sources, enabling flexible colonization without direct parental inheritance. In social insects like honey bees and bumble bees, social transmission facilitates the spread of gut symbionts via interactions including trophallaxis (food sharing) and contact with nest mates' feces or pollen provisions. For instance, in bumble bees (Bombus terrestris), newly emerged workers acquire their core gut microbiota, dominated by Gamma- and Betaproteobacteria, through exposure to fecal matter from nest mates, ensuring rapid colonization post-eclosion.^[21] This mode contrasts with vertical transmission by promoting microbial exchange across generations and colonies, enhancing community homogeneity among eusocial species.^[22] In human microbiomes, horizontal exchange of gut symbionts primarily happens via the fecal-oral route, with cohabiting individuals sharing up to 12% of gut microbial strains through close physical interactions and shared environments, independent of direct maternal inheritance. Breastfeeding contributes a non-vertical dimension by enabling broader household strain sharing, as maternal milk harbors bacteria that facilitate ongoing microbial transfer among family members, with median sharing rates reaching 50% in the first year of life. These processes play a key role in host adaptation by seeding diverse microbial communities that support metabolic and immune functions, such as the persistence of beneficial genera like Bifidobacterium and Bacteroides across developmental stages.^[23]^[24] Mutualistic outcomes of these transmissions include bolstered host digestion and immunity; in social bees, acquired gut symbionts reduce intestinal parasite loads by nearly an order of magnitude, conferring protection against entomopathogens like Crithidia bombi. Similarly, in corals, horizontal acquisition of algal symbionts (Symbiodiniaceae) from water currents and sediments—occurring in 80–85% of species—provides photosynthetic energy, enhancing host resilience to environmental stressors through the uptake of thermally tolerant genotypes. Unlike pathogen spread, which disrupts host health, symbiont transmission often stabilizes ecosystems by fostering cooperative microbial networks.^[21]^[25] Microbiome stability depends on community assembly rules, where weak, noncooperative interactions among microbes promote robust colonization and high diversity, while strong dependencies enforce predictable succession but risk failure if pioneers are absent. Disruptions, such as antibiotics or environmental changes, can lead to dysbiosis—characterized by low-diversity states and loss of mutualistic functions—potentially resulting in host pathologies like impaired immunity or metabolic imbalance.^[26]

Horizontal Gene Transfer

Horizontal gene transfer (HGT), also known as lateral gene transfer, is the movement of genetic material between organisms other than by vertical inheritance from parent to offspring, serving as a key molecular mechanism in evolution, particularly among prokaryotes.^[27] This process enables the rapid dissemination of advantageous traits, such as metabolic capabilities or resistance to environmental stresses, by allowing genes to jump across species boundaries without requiring whole-organism transmission.^[28] In bacteria and archaea, HGT is a primary driver of genomic plasticity, contributing to 1–16% of genes in various prokaryotic genomes depending on the lineage and ecological niche.^[27] The three primary mechanisms of HGT in prokaryotes are transformation, transduction, and conjugation. Transformation involves the uptake and incorporation of free, naked DNA from the environment into a recipient cell, a process facilitated by competence systems in species like Streptococcus pneumoniae and Bacillus subtilis.^[28] Transduction occurs when bacteriophages (viruses that infect bacteria) accidentally package host DNA during replication and transfer it to another bacterial cell upon infection, as observed in generalized transduction by phages like P1 in Escherichia coli.^[29] Conjugation is a direct cell-to-cell transfer of DNA, typically via plasmids or integrative conjugative elements, mediated by type IV secretion systems and pili that form physical bridges between donor and recipient cells, exemplified by the F-plasmid system in E. coli.^[28] These mechanisms often rely on mobile genetic elements like plasmids, transposons, and integrons to package and stabilize transferred DNA.^[30] Prominent examples of HGT include the spread of antibiotic resistance genes among bacterial populations. Genes encoding beta-lactamases or efflux pumps are frequently transferred via conjugation on plasmids, enabling pathogens like Klebsiella pneumoniae to acquire multidrug resistance rapidly in clinical settings and natural environments.^[30] Another case involves the endosymbiont Wolbachia, which transfers genes to insect hosts, contributing to reproductive manipulations such as cytoplasmic incompatibility—a phenomenon where embryos from uninfected females mated with infected males fail to develop. In species like the fruit fly Drosophila simulans, HGT of Wolbachia genome fragments to the host X chromosome has been documented, potentially enhancing host adaptation to the symbiont's effects.^[31] HGT profoundly influences prokaryotic evolution by accelerating gene acquisition and fostering innovation in metabolic pathways and stress responses. Gene acquisition rates vary widely, with estimates suggesting up to 10^−5 to 10^−3 transfers per gene per generation in dense bacterial communities, driven by ecological factors like population density and selective pressures.^[27] Such models underscore HGT's role in generating genetic diversity, often outpacing point mutations in adaptive evolution.^[32] Although rarer in eukaryotes due to more complex genomes and cellular barriers, HGT occurs and can confer significant fitness advantages. In bdelloid rotifers—ancient asexual animals—up to 8–10% of genes show evidence of horizontal acquisition, including fungal-derived genes for carbohydrate metabolism and desiccation tolerance, enabling survival in extreme environments like temporary ponds.^[33] These transfers, likely mediated by microbial intermediaries in the rotifers' desiccated states, illustrate HGT's potential to expand eukaryotic biochemical repertoires beyond vertical inheritance. HGT frequently underpins exchanges within microbial communities, including host-associated microbiomes.^[34]

Anthropological and Cultural Contexts

Mechanisms in Human Societies

In human societies, horizontal transmission of cultural elements occurs primarily through social learning processes such as imitation, where individuals replicate observed behaviors, and teaching, where explicit instruction conveys knowledge from one person to another. Diffusion through social networks further facilitates this transmission by allowing ideas, practices, and norms to spread via interactions among peers or acquaintances. Oral traditions serve as key vectors, preserving and disseminating narratives, values, and skills across generations without reliance on written records, while migration acts as a broader conduit, carrying cultural traits to new populations through human movement.^[35]^[36]^[37]^[38] Anthropological theories frame these processes by conceptualizing cultural elements as replicators analogous to biological genes. In memetics, introduced by Richard Dawkins in 1976, ideas or "memes" are units of cultural transmission that propagate horizontally between individuals, evolving through variation, selection, and retention in social environments. This perspective highlights how non-genetic information spreads independently of parent-offspring lines, emphasizing fidelity in replication during interpersonal exchanges.^[39] Social factors significantly influence the pathways of horizontal transmission, with kinship networks often prioritizing vertical or oblique transfers within family lines, whereas non-kin exchanges enable broader horizontal dissemination through alliances or interactions outside familial ties. In pre-modern societies, trade routes played a pivotal role by connecting distant groups, promoting the exchange of technologies, beliefs, and artistic motifs via merchant networks and intercultural contacts.^[40]^[41] In contemporary contexts, digital media have accelerated horizontal transmission by enabling rapid, global dissemination of social norms and languages through platforms that connect vast, non-local networks. Social media, for instance, facilitate the viral spread of linguistic innovations and behavioral standards, amplifying the reach and speed of cultural elements beyond traditional geographic constraints. This modern extension parallels biological pathogen transmission in its reliance on contact networks but operates through ideational rather than infectious vectors.^[42]

Examples from Cultural Evolution

One prominent historical example of horizontal transmission in cultural evolution is the spread of agriculture from the Fertile Crescent around 10,000 BCE, where farming practices disseminated primarily through the migration of early Neolithic populations rather than local invention or adoption.^[43] This process reshaped societies across the Near East and into Europe, as migrants introduced domesticated crops and livestock, leading to widespread agricultural adoption via intergroup contact.^[44] Similarly, writing systems diffused across Eurasia through adaptation and borrowing, as seen in the transmission of cuneiform from Mesopotamia to Elam in southwestern Iran during the early third millennium BCE and to Anatolia around the early second millennium BCE, where local scribes modified the script for new languages and administrative needs.^[45]^[46] These diffusions highlight how cultural innovations propagate laterally across populations, fostering interconnected Eurasian networks of knowledge exchange.^[47] In ethnographic contexts, horizontal transmission manifests in language borrowing within pidgins and creoles, where speakers from diverse linguistic backgrounds integrate vocabulary and structures from multiple sources during contact situations, such as colonial trade or labor migrations.^[48] For instance, Hawaiian Creole English incorporates elements from English, Hawaiian, and other Pacific languages, evolving through intergenerational horizontal exchange among communities.^[49] Among hunter-gatherer groups, tool-making techniques are shared horizontally via peer observation and collaborative practice, as observed in communities like the Mbendjele BaYaka, where adolescents learn foraging tools through informal interactions rather than direct parental instruction.^[50] This mode of transmission ensures the rapid dissemination of adaptive skills within and between bands, enhancing group survival without relying on vertical inheritance.^[51] Contemporary examples include the horizontal spread of viral memes on social media platforms, where digital content replicates and mutates through user sharing and remixing, analogous to cultural replicators in evolutionary terms.^[52] Memes like the "Distracted Boyfriend" image have propagated globally via imitation and adaptation across cultures, influencing humor and discourse.^[53] Likewise, the adoption of fashion trends among global youth cultures occurs through lateral diffusion via online networks and influencers, such as the rapid uptake of streetwear styles originating in urban Asia and spreading to Western markets.^[54] These instances demonstrate how modern media accelerates horizontal transmission, blending local and global elements into hybrid cultural expressions.^[55] To measure such diffusions, phylogenetic methods apply tree-based models to trace cultural trait evolution by comparing similarities in artifacts, languages, or practices, inferring historical transmission patterns while accounting for horizontal exchanges.^[56] For example, these approaches have reconstructed the spread of pottery styles across prehistoric societies by quantifying trait resemblances beyond vertical descent.^[57] Such analyses reveal the interplay of migration and contact in cultural phylogenies, providing empirical insights into non-vertical inheritance.^[58]

Implications and Applications

Epidemiological and Public Health Aspects

Horizontal transmission forms the basis of most epidemiological models for infectious diseases, as it describes the spread between individuals in a population rather than across generations. The classic Susceptible-Infected-Recovered (SIR) model, developed in the early 20th century, captures this dynamic by dividing the population into compartments: susceptible (S), infected (I), and recovered (R). The model's differential equations quantify the rate of horizontal spread, where the change in susceptibles is given by \frac{dS}{dt} = -\beta \frac{SI}{N}, with \beta as the transmission rate and N the total population; the infected compartment evolves as \frac{dI}{dt} = \beta \frac{SI}{N} - \gamma I, where \gamma is the recovery rate; and recovered individuals increase via \frac{dR}{dt} = \gamma I. These equations assume density-dependent horizontal contact, enabling predictions of epidemic peaks and final sizes, and have been adapted for various pathogens exhibiting direct or indirect horizontal modes, such as respiratory viruses.^[59] Public health interventions targeting horizontal transmission emphasize breaking chains of contact to reduce the effective reproduction number (R_t) below 1. Contact tracing, which identifies and isolates exposed individuals, has proven effective in containing outbreaks by limiting secondary infections, as demonstrated during the COVID-19 pandemic where rapid tracing significantly reduced the proportion of infections in modeled scenarios. Herd immunity thresholds, calculated as $1 - 1/R_0 where R_0 is the basic reproduction number, guide vaccination campaigns; for COVID-19 with an R_0 of approximately 2.5-3 for airborne horizontal spread, this implies 67-70% population immunity to halt transmission. Strategies like mask mandates and social distancing further disrupt airborne and droplet-mediated horizontal pathways, as evidenced by their role in lowering incidence during the 2020-2021 waves.^[60]^[61]^[62] Zoonotic spillover events, where pathogens jump from animal reservoirs to humans and subsequently spread horizontally, pose significant global challenges by initiating pandemics with high transmissibility. For instance, SARS-CoV-2 originated from bat reservoirs via an intermediate host, enabling rapid human-to-human horizontal transmission that led to over 700 million cases worldwide by 2023. Vaccination disrupts these chains by inducing immunity that prevents onward horizontal spread, as seen with measles vaccines reducing global estimated deaths by 73% from 2000-2018 through sustained herd effects. However, emerging variants and incomplete coverage in low-resource settings can sustain horizontal pandemics, underscoring the need for integrated surveillance.^[63]^[64] Key metrics for assessing horizontal transmission include incidence rates, which measure new cases per population unit over time (e.g., 10-20 per 100,000 weekly for seasonal influenza via respiratory horizontal spread), and secondary attack rates (SAR), the probability of infection among exposed contacts. Household SAR for COVID-19 has been reported as high as 45-49% in some studies, particularly for later variants among close contacts, highlighting the role of intimate horizontal interactions in amplification. These indicators inform targeted interventions, with higher SARs signaling the need for enhanced isolation protocols.^[65]^[66]^[67]

Evolutionary and Ecological Significance

Horizontal gene transfer (HGT) plays a pivotal role in accelerating biological evolution by enabling the rapid acquisition of adaptive traits across species boundaries, thereby promoting speciation in prokaryotes and eukaryotes alike. In bacteria, HGT facilitates the dissemination of beneficial genes, such as those conferring metabolic innovations, which can lead to the emergence of new lineages by altering phylogenetic trajectories and enhancing adaptive potential. For instance, in plants, HGT via mechanisms like bacterial endosymbiosis (e.g., through Agrobacterium) introduces novel genetic material that enhances diversity and adaptability, mitigating inbreeding depression and fostering hybrid vigor, or heterosis, resulting in superior growth and yield in offspring compared to parental lines. This process exemplifies how horizontal transmission contributes to evolutionary diversification by integrating novel alleles into populations. Ecologically, horizontal transmission of symbionts and genes sustains biodiversity by facilitating dynamic exchanges within communities, particularly through keystone species that anchor ecosystem stability. In coral reefs, where corals act as foundational architects supporting vast marine biodiversity, horizontal acquisition of algal symbionts (Symbiodiniaceae) from the environment allows hosts to adapt to varying conditions, such as temperature fluctuations, thereby preserving reef integrity and associated species diversity. Similarly, in microbial communities, horizontal symbiont exchange among insects and their hosts promotes resilience and functional redundancy, preventing cascading extinctions and maintaining trophic balances in diverse habitats. In cultural evolution, horizontal transmission drives the diffusion of innovations by enabling rapid idea spread across non-kin networks, as outlined in dual-inheritance theory, which posits that cultural traits evolve alongside genetic ones through mechanisms like imitation and social learning. This theory, developed by Boyd and Richerson, integrates horizontal processes to explain how cultural variants, such as technological advancements, propagate efficiently in human societies, accelerating adaptive change beyond genetic constraints. Over long terms, such transmission fosters cultural convergence in globalized contexts, where widespread horizontal exchanges homogenize practices, as seen in the adoption of global norms through media and migration, potentially reducing cultural diversity but enhancing collective problem-solving. Long-term evolutionary impacts of horizontal transmission include accelerated resistance in pathogens, where HGT rapidly disseminates antibiotic resistance genes among bacterial populations, complicating medical interventions and driving adaptive radiations in microbial ecosystems. In cultural domains, persistent horizontal flows in interconnected societies promote convergence toward shared ideologies and technologies, influencing global trajectories like economic standardization while risking the erosion of localized traditions.

References

[1]
Host Range, Host–Virus Interactions, and Virus Transmission - PMC
In horizontal transmission, viruses are transmitted among individuals of the same generation which encompasses both direct and indirect modes. Horizontal ...
[2]
10.3D: Infectious Disease Transmission - Biology LibreTexts
Nov 23, 2024 · All of the above modes are examples of horizontal transmission because the infecting organism is transmitted from person to person in the same ...
[3]
Transmission routes | Research Starters - EBSCO
Horizontal transmission refers to the passing of a disease or pathogen from one person to another in the same generation. The disease is not passed from woman ...
[4]
Horizontal Gene Transfer - PMC - NIH
Horizontal gene transfer (HGT) is the movement of genetic information between organisms, a process that includes the spread of antibiotic resistance genes ...
[5]
Does horizontal transmission invalidate cultural phylogenies? - PMC
Mar 18, 2009 · In particular, it is frequently argued that the horizontal transmission of traits is rampant in cultural evolution: Human cultural evolution ...Missing: definition | Show results with:definition
[6]
Horizontal Gene Transfer and the History of Life - PMC - NIH
Horizontal gene transfer is a major evolutionary force that constantly reshapes microbial genomes. Emerging phylogenetic methods use information about ...
[7]
Horizontal gene transfer in evolution: facts and challenges - Journals
Nov 28, 2009 · On this background, the concept of horizontal gene transfer between organisms emerged at the beginning of the 1990s as an alternative ...Abstract · How important is horizontal... · Horizontal gene transfer and...
[8]
Vertical Transmission - an overview | ScienceDirect Topics
The advantage to the host of vertical transmission is that its offspring are assured of gaining a compatible symbiont – or, at least, a symbiont compatible with ...
[9]
Horizontal and vertical transmission of viruses in the honey bee ...
In horizontal transmission, viruses are transmitted among individuals of the same generation, while vertical transmission occurs from mothers to their offspring ...
[10]
The advantages and disadvantages of horizontal gene transfer and ...
Reduction of h leads to the "origin of species" composed of coherent groups of genomes. ... Although horizontal transmission is very important prior to the ...
[11]
Transovarial Transmission - an overview | ScienceDirect Topics
Females infected vertically or horizontally transmit their infection transovarially to first-instar larvae. These larvae transmit virus transstadially through ...
[12]
I. Review of Scientific Data Regarding Transmission of Infectious ...
Nov 27, 2023 · The most common mode of transmission, contact transmission is divided into two subgroups: direct contact and indirect contact. I.B.3.a.i. Direct ...
[13]
Modes of transmission of virus causing COVID-19: implications for ...
Mar 29, 2020 · Therefore, transmission of the COVID-19 virus can occur by direct contact with infected people and indirect contact with surfaces in the ...
[14]
Principles of Epidemiology | Lesson 1 - Section 10 - CDC Archive
Direct contact occurs through skin-to-skin contact, kissing, and sexual intercourse. · Droplet spread refers to spray with relatively large, short-range aerosols ...
[15]
Malaria Surveillance --- United States, 2008 - CDC
Jun 25, 2010 · The infection is transmitted by the bite of an infective female Anopheles species mosquito. P. falciparum and P. vivax species cause the most ...
[16]
Soil-transmitted helminth infections
Jan 18, 2023 · Soil-transmitted helminths are transmitted by eggs that are passed in the faeces of infected people. Adult worms live in the intestine where ...
[17]
About Soil-transmitted helminths - CDC
Jun 13, 2024 · Soil-transmitted Helminths, or STH, are parasitic worms that live in the human intestine. They spread through soil or water contaminated by ...
[18]
Integrative genomic analysis reveals mechanisms of immune ...
Oct 9, 2020 · The mechanisms behind the ability of Plasmodium falciparum to evade host immune system are poorly understood and are a major roadblock in ...
[19]
Neisseria gonorrhoeae host adaptation and pathogenesis - Nature
Feb 12, 2018 · gonorrhoeae is an obligate human pathogen with the ability to evade and modulate both the innate and adaptive immune systems to benefit its ...
[20]
Immune evasion and persistence in enteric bacterial pathogens - PMC
Jan 8, 2023 · Some bacterial enteropathogens have acquired an arsenal of virulence factors with which they neutralize all these formidable barriers to infection.
[21]
A Comprehensive Immunization Strategy to Eliminate Transmission ...
Dec 8, 2006 · The work group examined the progress made since 1991 in implementing the U.S. strategy to eliminate HBV transmission (e.g., vaccination ...
[22]
[PDF] syphilis-pocket-guide-final-508.pdf - CDC
Syphilis Transmission. Two means of syphilis transmission: sexual and vertical. • Sexual: Person to person via vaginal, anal, or oral sex through direct ...
[23]
Socially transmitted gut microbiota protect bumble bees against an ...
Nov 14, 2011 · We now show that the presence of these microbiota protects bee hosts against a widespread and highly virulent natural parasite (Crithidia bombi) ...
[24]
Dynamic microbiome evolution in social bees | Science Advances
Mar 29, 2017 · We conduct wide sampling across the phylogeny of these corbiculate bees and reveal a dynamic evolutionary history behind their microbiota.Dynamic Microbiome Evolution... · Results · Materials And Methods
[25]
The person-to-person transmission landscape of the gut and oral ...
Jan 18, 2023 · To examine horizontal gut microbiome ... Strain tracking reveals the determinants of bacterial engraftment in the human gut following fecal ...
[26]
Impact of breastfeeding and other early-life factors on the ... - Frontiers
The aim of this review is to describe oral microbiome development in early life, with a particular focus on the impact of breastfeeding and infant diet.
[27]
https://www.nature.com/articles/nrg3962
[28]
Ecological rules for the assembly of microbiome communities - PMC
Feb 19, 2021 · This study develops ecological theory that reveals the rules underlying the assembly of such host-associated microbiota.Missing: dysbiosis | Show results with:dysbiosis
[29]
Horizontal gene transfer: building the web of life - Nature Reviews Genetics
### Summary of Horizontal Gene Transfer (HGT) Mechanisms and Impacts
[30]
The chromosomal organization of horizontal gene transfer in bacteria
Oct 10, 2017 · In prokaryotes, HGT takes place by three main mechanisms: natural transformation, conjugation, and transduction. Mobile genetic elements ...
[31]
CRISPR–Cas enhances HGT by transduction - Nature
Feb 26, 2018 · The major mechanisms of horizontal gene transfer (HGT) in bacteria are natural transformation, conjugation and transduction (phage-mediated transfer of ...Missing: paper | Show results with:paper<|control11|><|separator|>
[32]
Antibiotic resistance in the environment | Nature Reviews Microbiology
Nov 4, 2021 · Antibiotic resistance is a global health challenge, involving the transfer of bacteria and genes between humans, animals and the environment.
[33]
Genome fragment of Wolbachia endosymbiont transferred to ... - PNAS
At present, neither mechanism nor process involved in the Wolbachia–insect horizontal gene transfer is understood. Through generations of host insects, ...
[34]
Assessing the Probability of Detection of Horizontal Gene Transfer ...
Feb 20, 2012 · Here we draw on statistical approaches to population genetic theory to construct a cohesive probabilistic framework for investigation of HGT of exogenous DNA ...
[35]
A global survey of prokaryotic genomes reveals the eco-evolutionary ...
Mar 5, 2024 · Our study covers an unprecedented scale of integrated horizontal gene transfer and environmental information, highlighting broad eco-evolutionary trends.
[36]
Evidence for extensive horizontal gene transfer from the draft ...
It has been proposed that bdelloid rotifers are ancient asexual and ameiotic organisms, and that HGT serves as a source of genetic diversity in the absence of ...
[37]
Horizontal gene transfer in human-associated microorganisms ...
Apr 11, 2019 · Horizontal gene transfer (HGT) is widespread in the evolution of prokaryotes, especially those associated with the human body.
[38]
The multiple roles of cultural transmission experiments in ... - Journals
Sep 19, 2008 · ... social learning mechanisms such as imitation, teaching or language. This can be contrasted with the acquisition of information via genetic ...
[39]
Social Networks and Knowledge Transmission Strategies among ...
Oct 24, 2018 · In small-scale societies, children's acquisition of cultural knowledge is said to mostly rely on observation, imitation, teaching, and ...
[40]
Oral traditions and expressions including language as a vehicle of ...
Oral traditions and expressions are used to pass on knowledge, cultural and social values and collective memory. They play a crucial part in keeping cultures ...Missing: vectors anthropology<|control11|><|separator|>
[41]
https://academic.oup.com/edited-volume/34513/chapter/292851576
[42]
The Selfish Gene - Richard Dawkins - Oxford University Press
Free delivery 25-day returnsThe Selfish Gene has become a classic exposition of evolutionary thought. Professor Dawkins articulates a gene's eye view of evolution.
[43]
Female friendship and the cultural transmission of low-fertility values
May 30, 2025 · We examine in detail the foundational mechanistic routes for cultural change that close personal friendships provide and relate them to low ...
[44]
Cultural Exchanges in World History - Oxford Academic
This article argues that cross-cultural interactions and exchanges have influenced the development of all or almost all peoples and societies throughout the ...
[45]
A Cultural Evolution Approach to Digital Media - PubMed Central - NIH
Digital media can therefore be considered as a technology that makes cultural transmission more preservative. Cinderella does not need to be listened to, ...Missing: horizontal norms
[46]
Modeling the European Neolithic expansion suggests predominant ...
Aug 25, 2025 · Many archeologists suggested migration as a potential driver of the spread of agriculture, though later some proposed cultural diffusion, where ...
[47]
The Origins of Agriculture in the Near East | Current Anthropology
This process took place across the entire Fertile Crescent during a period of dramatic post-Pleistocene climate and environmental change with considerable ...
[48]
The Evolution and Diffusion of Writing - jstor
terminative writing system in the North- eastern Semitic area in the second millennium. B.C. spreading throughout Asia along with a religion based upon time ...
[49]
[PDF] The Early Development of the Cuneiform Writing System, and Its ...
In this paper, I examine the early development of cuneiform writing in. Mesopotamia and its regional adaptation in Iran during the late 4th and.
[50]
Modeling the Emergence of Contact Languages | PLOS One
As with bacteria or viruses in biological evolution, the evolution of languages is marked by horizontal transmission; but to date no reliable quantitative tools ...
[51]
[PDF] What Do Creoles and Pidgins Tell Us About the Evolution of ...
In any case, creoles developed in those settings where interactions between. Europeans and non-Europeans were regular during the initial, homestead phase of the ...
[52]
How Do Hunter-Gatherer Children Learn Subsistence Skills?
Oct 9, 2017 · Learning begins early in infancy, when parents take children on foraging expeditions and give them toy versions of tools.
[53]
Cultural transmission vectors of essential knowledge and skills ...
These vanishing skills include identifying medicinal plants and handmaking traditional clothes, tools, and musical instruments that are now more readily ...
[54]
[PDF] Five Misunderstandings about Cultural Evolution
Recent debates about the utility of “memes” have revealed some fundamental misunderstandings about the nature of cultural evolution.Missing: scholarly | Show results with:scholarly
[55]
[PDF] Beyond the Meme: Development and Structure in Cultural Evolution
... transmission or the size of the cultural breeding population? Some research ... horizontal transfer of information from other lineages as contaminating ...
[56]
Global Fashion: A Window into Globalization - Publish
May 15, 2015 · Exploring the fashion trends of past and current cultures gives unique insight into globalization and the understandings held about ...
[57]
The Globalization of Fashion: How Cultures Around the World ...
Oct 18, 2023 · From Tokyo's avant-garde streetwear to Milan's timeless couture, trends are less about geographical origins and more about global resonance.
[58]
The uses and abuses of tree thinking in cultural evolution - PMC - NIH
Phylogenetic methods have the potential to influence our understanding of the evolution of specific domains of culture (languages, artefacts) as well as of the ...
[59]
(PDF) A Phylogenetic Approach to Cultural Evolution - ResearchGate
Aug 5, 2025 · Advances in phylogenetic methods offer new possibilities for the analysis of cultural evolution, including estimating the rate of evolution and ...
[60]
The potential to infer the historical pattern of cultural macroevolution
May 17, 2021 · Phylogenetic reconstructions of trait evolution offer the potential to infer what cultural variants might have been present in the past, how ...Missing: similarity | Show results with:similarity
[61]
[PDF] An Introduction to Deterministic Infectious Disease Models
Section 2 uses the SIR model to explain the concepts and mathematics underlying deterministic infectious disease modeling, including the parameters of the model ...
[62]
The importance of timely contact tracing — A simulation study
Our simulation study shows how timely contact tracing can help contain the current pandemic, the effectiveness of which can be measured by the diagnostic serial ...
[63]
Coronavirus disease (COVID-19): Herd immunity, lockdowns and ...
Herd immunity against COVID-19 should be achieved by protecting people through vaccination, not by exposing them to the pathogen that causes the disease.Missing: horizontal | Show results with:horizontal
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Identifying airborne transmission as the dominant route for ... - PNAS
Our results show that the airborne transmission route is highly virulent and dominant for the spread of COVID-19.
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Zoonotic spillover: Understanding basic aspects for better prevention
The transmission of pathogens from wild animals to humans is called “zoonotic spillover”. Most human infectious diseases (60-75%) are derived from pathogens ...
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Principles of Epidemiology | Lesson 3 - Section 2 - CDC Archive
For a secondary attack rate, 10n usually is 100%. EXAMPLE: Calculating Secondary Attack Rates. Consider an outbreak of shigellosis in which 18 persons in 18 ...
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Attack rates amongst household members of outpatients with ...
Mar 31, 2021 · The attack rate was 16% in asymptomatic household members and 42% in RT-PCR negative contacts. Older adults had higher antibody titres than ...
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Secondary Attack Rate, Transmission and Incubation Periods ... - CDC
Contact tracing data of SARS-CoV-2 Omicron variant cases during December 2021 in Cantabria, Spain, showed increased transmission (secondary attack rate 39%) ...