Alternatively, a microorganism may emerge as a pathogen or acquire new public health importance because of changes in host susceptibility to infection. Factors influencing host susceptibility within the population as a whole include increases in the number of immunocompromised patients; increased use of immunosuppressive agents, particularly among persons receiving cancer chemotherapy or undergoing organ transplantation; aging of the population; and malnutrition.
What factors influence host susceptibility to infection?
Many factors influence the susceptibility of populations to infection, including increases in diseases that cause immunosuppression, increased use of immunosuppressive agents, aging of the population, and malnutrition. In considering these categories, it should be recognized that "host susceptibility" is not a single entity.
What are the risk factors for host host disease?
Host susceptibility is affected by many factors such as nutritional status, intercurrent disease, pregnancy, immunosuppressive drugs and malignancy.
How does susceptibility to infectious diseases affect plant growth?
Susceptibility to infectious diseases caused by pathogens affects most plants in their natural habitat and leads to yield losses in agriculture. However, plants are not helpless because their immune system can deal with the vast majority of attackers.
What determines the frequency of microorganisms causing disease?
Occurrence of disease is a function of several major variables: the virulence of the microorganism (i.e., its possession of factors that allow it to cause illness), its mode of transmission (i.e., how it gets to the host), and host susceptibility (i.e., how well the host can defend itself against the microorganism).
What are the factors that affect host susceptibility?
What is host susceptibility?
What genes are associated with leprosy?
What are the properties of a virus?
Which animal is the preferred host for experimentation?
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What are four 4 factors that influence the susceptibility of a host?
Susceptibility and response to an agent are influenced by factors such as genetic composition, nutritional and immunologic status, anatomic structure, presence of disease or medications, and psychological makeup.
Which factors make you a susceptible host?
We all have different susceptibility Multiple innate factors (e.g., age, nutritional status, genetics, immune competency, and pre-existing chronic diseases) and external variables (e.g., concurrent drug therapy) influence the overall susceptibility of a person exposed to a virus.
What are 3 factors that increase the susceptibility to infection?
Life style risk factors such as aging, poor nutrition, infection and exposure to toxicants can also increase susceptibility to illnesses.
Who are the susceptible hosts of infection?
Susceptible Host – it's either a baby, an elderly person or someone with a weakened immune system that is susceptible to the infectious agent.
What are susceptibility factors?
In this article, we define “susceptibility factors” broadly to include populations at risk (e.g., the very young, elderly, or genetically at risk), known risk factors, and known protective factors (“farm” exposure in utero or in infancy).
What is the definition of susceptible host?
SUSCEPTIBLE HOST The person who is at risk for developing an infection from the disease.
What factors determine whether someone will catch a virus?
Most viruses have an affinity for specific tissues; that is, they display tissue specificity or tropism. This specificity is determined by selective susceptibility of cells, physical barriers, local temperature and pH, and host defenses.
Which three main elements make up the chain of infection?
Infectious agent (pathogen) Reservoir (the normal location of the pathogen) Portal of exit from the reservoir. Mode of transmission.
How immune status affects susceptibility to infection?
Underactivity of the immune system, or immunodeficiency, can increase the risk of infection. You may be born with an immunodeficiency (known as primary immunodeficiency, PID), or acquire it from a medical treatment or another disease (known as secondary immunodeficiency).
What is a susceptible host quizlet?
susceptible host. a person who is unable to resist infection by a particular pathogen. Acute infection (common cold or flu) short term illness or rapid onset of disease, a relatively brief period of symptoms, and resolution within days. Chronic infection.
How do you prevent a susceptible host?
Break the chain by cleaning your hands frequently, staying up to date on your vaccines (including the flu shot), covering coughs and sneezes and staying home when sick, following the rules for standard and contact isolation, using personal protective equipment the right way, cleaning and disinfecting the environment, ...
How does age affect susceptibility to infection?
As you grow older, your immune system does not work as well. The following immune system changes may occur: The immune system becomes slower to respond. This increases your risk of getting sick.
What is a susceptible host quizlet?
susceptible host. a person who is unable to resist infection by a particular pathogen. Acute infection (common cold or flu) short term illness or rapid onset of disease, a relatively brief period of symptoms, and resolution within days. Chronic infection.
Which of the following are the host factors?
Host factors include those that are largely fixed (such as demographics, ancestry, and genetics) and those that are influenced by early life exposure to other risk factors. The risk of ARF is strongly influenced by specific demographic factors, particularly age and ethnicity (discussed further later).
How do you prevent a susceptible host?
Break the chain by cleaning your hands frequently, staying up to date on your vaccines (including the flu shot), covering coughs and sneezes and staying home when sick, following the rules for standard and contact isolation, using personal protective equipment the right way, cleaning and disinfecting the environment, ...
What is a susceptible individual who can harbor the disease called?
host a person or other living organism that is susceptible to or harbors an infectious agent under natural conditions.
Host Susceptibility Factors to Bacterial Infections in Type 2 Diabetes
Introduction. Globally, the number of people with Type 2 diabetes (T2D) or diabetes mellitus is projected to grow to 366–440 million by 2030, with three quarters of the increase in low- to middle-income countries .The burden of communicable diseases is concentrated in low-income and resource-strapped regions, and one could predict that diabetes-related infections will rise significantly in ...
Host factors influencing susceptibility to HIV infection and AIDS ...
Transmission of HIV first results in an acute infection, followed by an apparently asymptomatic period that averages ten years. In the absence of antiretroviral treatment, most patients progress into a generalized immune dysfunction that culminates in death. The length of the asymptomatic period varies, and in rare cases infected individuals never progress to AIDS.
What determines susceptibility to virus infection?
We all have different susceptibility Individuals differ in their susceptibility to viral infections, and the clinical course of any patient infected with a virulent virus is ultimately determined by the complex patient-virus interaction.
Host Susceptibility - an overview | ScienceDirect Topics
Host susceptibility to a virus can be markedly affected by age and sex. For many viruses, young animals have a higher mortality than older animals (Figure 3).For other viruses, older animals may exhibit increased susceptibility, such as with human coronaviruses (see Chapter 16, Emerging virus diseases). The sex of the animal often affects the outcome of virus infection.
The effect of aging on susceptibility to infection - PubMed
The appearance of many well-recognized "diseases of aging" tends to mask a similar rise in the susceptibility of the aged to infections. The immune response, particularly cell-mediated immunity, declines in efficiency with age, but this change alone does not explain the increased occurrence of infec …
1.2.6 Susceptible hosts and risk factors - Open University
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What is the leading cause of increased host susceptibility to infection?
However, on a global scale, probably the leading cause of increased host susceptibility to infection is malnutrition. While accurate data on the prevalence of malnutrition are difficult to obtain, problems are accentuated in developing countries, in areas of political unrest, and among marginalized populations in the United States and other affluent nations. In Mexico, according to a probabilistic survey in 1990, 42.3% of children under 5 years of age had some degree of malnutrition (40).
What are the factors that affect the susceptibility of a population to infection?
Many factors influence the susceptibility of populations to infection, including increases in diseases that cause immunosuppression, increased use of immunosuppressive agents, aging of the population, and malnutrition. In considering these categories, it should be recognized that "host susceptibility" is not a single entity. Changes in host susceptibility may be due to various mechanisms, with each mechanism having a greater or lesser impact on the ability of the host to defend itself against infection with specific pathogens or classes of pathogens. These are very complex biologic systems; nonetheless, the general categories outlined below may be of value in identifying groups or populations for further study.
Why is host susceptibility important?
Host susceptibility (and changes in the susceptibility to infection of groups within the general population) is a critical variable in assessing the public health effects and understanding the emergence and spread of pathogenic microorganisms. Surveillance within populations with increased susceptibility to infection may allow identification of new pathogens before they are recognized within the general population. Studies designed to identify the reasons for the increased susceptibility of a specific population to a specific agent may reveal how a microorganism is able (or not able) to breach normal host defense mechanisms. Finally, from a public health standpoint, risk management strategies for emergent foodborne pathogens must clearly identify and focus on populations with increased susceptibility to infection.
How does malnutrition affect the host?
Malnutrition increases host susceptibility through a number of mechanisms. It weakens epithelial integrity and may have a profound effect on cell-mediated immunity, with functional deficiencies in immunoglobulins and defects in phagocytosis. Malnutrition also may initiate a "vicious cycle" of infection predisposing to malnutrition and growth faltering, which in turn may lead to an increased risk for further infection ( 40, 41 ). In studies in Bangladesh, malnourished and well-nourished children had the same number of infections with diarrheal pathogens such as enterotoxigenic E. coli; however, diarrhea in malnourished children was of longer duration and had greater potential long-term nutritional consequences (42). Overall, malnutrition appears to result in a 30-fold increase in the risk for diarrhea-associated death (40).
Why are pathogens important to the public?
A pathogen may emerge as an important public health problem because of changes in itself or its transmission pathways. Alternatively, a microorganism may emerge as a pathogen or acquire new public health importance because of changes in host susceptibility to infection. Factors influencing host susceptibility within the population as a whole include increases in the number of immunocompromised patients; increased use of immunosuppressive agents, particularly among persons receiving cancer chemotherapy or undergoing organ transplantation; aging of the population; and malnutrition. In considering the emergence of foodborne pathogens and designing interventions to limit their spread, the susceptibility of these population subgroups to specific infections should be taken into account.
What are the effects of immunosuppressive agents on the gut?
Aside from the direct immunosuppressive effect of the agents administered to these patients, other associated factors may contribute to susceptibility to infection. Many, if not most, patients receiving chemotherapy or immunosuppressive agents are also treated with antimicrobial drugs, which can have profound effects on the bacterial flora of the intestinal tract. These disturbances of gut microbial ecology may predispose to colonization and infection with other microorganisms, some of which may have increased virulence. Many chemotherapeutic agents have direct toxicity for the gut mucosa; the resulting mucositis increases the susceptibility of these patients to bloodstream infections with whatever microorganisms are present in gut. The concentration of these highly susceptible patients on certain wards or units in a hospital may also increase the risk for nosocomial transfer of specific microorganisms. For example, vancomycin-resistant enterococci (VRE) (which, at least in Europe, have been associated with food [ 24 ]) have emerged as a substantive problem in cancer centers and transplant units ( 25 - 27 ). Persons who are immunosuppressed or have serious underlying illness are much more susceptible to colonization and infection with the organism. In some oncology and transplant units, more than 10% of patients are colonized or infected with VRE ( 26, 27 ), providing well-documented opportunities for transfer of the organism to other immunosuppressed hosts in the same unit.
Why is Toxoplasma gondii important?
Before AIDS, Toxoplasma gondii was of concern primarily because of the risk for congenital infection in infants of mothers who had acute illness during pregnancy. T. gondii is now the leading cause of space-occupying cranial lesions in persons with AIDS ( 14, 15 ); data from the 1980s suggest that 5% to 10% of AIDS patients get toxoplasmic encephalitis (16). In an estimated 50% of cases, Toxoplasma is transmitted by food (17). In this context, Toxoplasma must be regarded as an important emerging pathogen in this patient population.
What are the mechanisms of host specificity?
The mechanisms of host specificity have been extensively studied in many plant-pathogenic fungi , especially in fungal pathogens causing disease on economically important crops. Specifically, genes involved in host specificity have been identified during the last few decades. In this overview, we describe and discuss these host-specificity genes.
What is the host species specificity of a plant?
Most plant pathogenic fungal species have a narrow range of plant species in which they cause disease, a phenomenon we here call ‘host species specificity’. The collective host range of some fungal species, such as Fusarium oxysporum ( F. oxysporum ), can be very large, but then individual strains are often limited to infect one or ...
How many layers of immunity do plants have?
To defend themselves against fungal pathogens, plants have evolved two layers of immunity ( Jones and Dangl, 2006 ).
Why is compartmentalization important in pathogens?
The compartmentalization of a genome thus allows pathogens to harbor fast-evolving genes without affecting the stability of core genes. 7. Conclusions and perspectives. Both proteins and secondary metabolites can determine host specificity in plant pathogenic fungi.
Can fungi cause disease?
Fortunately, no fungus can cause disease on all plant species, and although some plant-pathogenic fungi have quite a broad host range, most are highly limited in the range of plant species or even cultivars that they cause disease in. The mechanisms of host specificity have been extensively studied in many plant-pathogenic fungi, ...
What are the factors that affect host susceptibility?
Host susceptibility is affected by many factors such as nutritional status, intercurrent disease, pregnancy, immunosuppressive drugs and malignancy. Previously mild or clinically inapparent infections can cause severe disease when host immunity falls, such as occurs in strongyloidiasis, in which the parasite is capable of multiplying by autoinfection within its host, and fatal amebiasis may occur if corticosteroids are administered.
What is host susceptibility?
Host Susceptibility. Host susceptibility plays a significant role in the development of clinical leprosy. Various genes and regions in the human genome have been linked to or associated with susceptibility to leprosy per se or with a particular type of leprosy.
What genes are associated with leprosy?
These include HLA DR2 and the Taq1 polymorphism of the vitamin D receptor gene, Alleles in the PARK2 and PACRG region on chromosome 6 are associated with susceptibility to leprosy in Vietnamese and Brazilian patients. 10,11 PARK2 is expressed by both Schwann cells and macrophages. It is a ubiquination E3 ligase. However, this finding was not reproduced in a study of six single nucleotide polymorphisms in these regions in Indian patients. 12
What are the properties of a virus?
Virus virulence and host susceptibility are interdependent properties that are determined by the virus–host combination and that together result in the manifestations of infection. A virus that is virulent in one setting may be innocuous in another , and a host may be susceptible or resistant depending upon age, route of infection , or properties of the virus .
Which animal is the preferred host for experimentation?
The rat is the preferred host for experimentation because it is highly susceptible, has a longer adult nematode survival time, and good reproducibility of experimental infections. In Sprague Dawley rats, infections terminate between 11 and 14 days, whereas in albino Wistar rats, it terminates between 18 and 21 days. In the laboratory, N. brasiliensis is maintained by serial passage in male rats inoculated SC with 3000 L 3. 66,78
