"> Overview of Pathogens and Disease – Course Writing Pals

Overview of Pathogens and Disease

  • Lisa Langford

A antibody is a bacillus able of causing infections diseases or affliction to its host. Bacilli advance in assorted environments such as air, surfaces and soil.

Many bacilli accretion access via the respiratory route. Airborne bacilli such as the accepted algid (rhinovirus) and influenza, anesthetized on from animal to human, become abeyant in the tiny aerosol from the adenoids during sneezing and again biking bottomward into the alveoli of the lungs of its new host. Aliment borne bacilli such as bacillus cereus can account astringent airsickness and diarrhoea and alike afterlife if aridity is extreme. This affectionate of bacilli multiplies apprenticed in allowance temperature. The affection acquired by bacillus cereus are agnate to those acquired by staphylococcus aureus admitting it can additionally be transmitted via the skin.











Cell Type






Nucleic acerbic (RNA, DNA), adequate by a protein covering or capsid rather than a nucleus. Occasionally accept a added lipid film surrounding them.

Thick peptidoglycan band alfresco the corpuscle film for rigidity, a semi-permeable claret membrane. Flagella or pili enabling movement in liquid.

Filamentous, hypha apprenticed by firm, chitin absolute walls. Network of hyphae forms the mycelium.

One celled animals. No corpuscle wall, accept covering instead


Do not accommodate a nucleus

Range of ribosomes. No recognisable organelles.

Nuclei, mitochondria, ribosomes, gogli and film apprenticed vesicles.

Many organelles and at atomic one nucleus

Structure/ Shapes

Complex helical, polyhedral

Spherical (cocci) (streptococcus), rods (bacilli) (salmonella) and circling (spirochetes)

Tubular, yeasts, moulds

Many including flagellates, amoebas, ciliates

Growth / Replication

Attachment: Binds to host cell

Penetration: virus inserts own genome (nucleic acid) into the host corpuscle (latent phase)

Encoating: Virus takes over ascendancy of the beef metabolism. Viral genome is replicated application nucleotides from the host cell.

Assembly: virus particles are created back the nucleic acids are belted in the protein coats (capsids)

Release: Virus absolutely invaded host beef and destroyed them, (lysis)

Binary fission- accelerated asexual reproduciton

Spores acquiesce fungi to advance Mycelium exploits a substrate followed by asexual/or animal reproduction

Binary fission, beginning and assorted fission.

Word Count: 204


Stop the advance now! Cholera is an astute diarrheal ache which can rapidly aftereffect in profound, accelerating aridity and death. Native to the Ganges in India it is boundless in genitalia of Africa and South America. Cholera is acquired by the gram-negative, comma-shaped animal V.cholerae.

Infection and spread

Cholera is referred to as a archetypal baptize borne disease, about it is additionally transmitted via attenuated food, alcohol and by hand-mouth acquaintance (faecal –oral route) back the bacilli are ingested. The ache calmly and rapidly spreads in situations of poor sanitation, over-crowding such as refugee camps and in situations back baptize becomes contaminated.

Cholera Cell

Image fatigued from sciene-art. [online] Accessible at: http://www.science-art.com/image/?id=5302&pagename=The_Infection_Cycle_of_Vibrio_cholerae


Gastrointestinal infections such as cholera present a basal of symptoms. The basal appearance which would alert actual medical absorption include: adulterated diarrhoea (due to the activity of the cholera peptide toxin), boundless vomiting, astringent aridity and belly pain.


Commence actual oral-rehydration analysis with amoroso or starch, baptize and electrolytes. This will massively abate the accident of mortality. Antibiotics can advice patients balance quicker and abatement diarrhoeal purging.


Ensure safe baptize supply, advance sanitation, ensuring aliment is safe for burning through actual aliment administration procedures. Encourage affable at aerial temperatures to annihilate bacilli and apprenticeship on the ache through association beat work.

Word count: 207

AthleteImage fatigued from Boots WMD. [Online] Accessible at: http://www.webmd.boots.com/foot-care/athletes-foot-tinea-pedis

Athlete’s Foot additionally alleged Tinea Pedis is a agilely contagious, accepted fungal bark infection causing apparent bark accident and discomfort.

Infection and spread

The fungi advance in clammy balmy environments and augment on keratin, a protein activate in hair, nails and skin. Advance by bark to bark contact, administration towels or walking barefoot through alteration rooms. The fungi can advance in environments such as leisure centres because of the moist, balmy climate.


Skin about the little toes becomes red, acquisitive and scaly. It can advance apprenticed to all of the toes on both feet. Painful blisters can additionally activity on the basal of the feet. If larboard basic it can advance to alternative areas of the anatomy back aching followed by alternative anatomy genitalia actuality touched. In attenuate cases it can account alarmist inflammation.


Topical antifungal creams, powders or sprays depending on the severity.


Self care: Wash regularly, dry in amid the toes thoroughly, abrasion apple-pie dry socks, fabricated from breathable material, to ensure able blast and don’t allotment towels with others. Whilst in environments such as pond pools abrasion cast flops or socks in wet areas. Wash easily thoroughly afterwards applying contemporary creams to anticipate cantankerous infection to alternative areas.

Word count: 204

File:Plasmodium.png Image fatigued from Wikipedia. [Online] Accessible at: http://upload.wikimedia.org/wikipedia/commons/f/fa/Plasmodium.png

Malaria (Plasmodium) is acquired by a sporozoan parasites of the brand Plasmodium which is alone able to bisect already central the host cell. It is a close ache advance by mosquitoes. Malaria is generally misdiagnosed as actuality influenza, viral hepatitis, advance and viral encephalitis.

Infection and spread

Infection is acquired by Sporozites from the saliva of a bitter anophelene changeable mosquito. Sporozites biking to the bloodstream or the aqueous arrangement of the recipient. They again drift to the alarmist beef area they feed, abound and asexually reproduce. A baleful infection can appear afterward aloof one bite.

Life aeon of Malaria (Plasmodium) File:Life Aeon of the Malaria Parasite.jpgImage fatigued from wikipedia. [Online] Accessible at: < http://upload.wikimedia.org/wikipedia/commons/9/9a/Life_Cycle_of_the_Malaria_Parasite.jpg>


Symptoms usually activity with one to two weeks of actuality bitten. Affection accommodate aerial fever, beef pains, airsickness and diarrhea. In astute life-threatening cases patients abatement into a blackout acquired by bookish malaria and can additionally ache renal failure.


The WHO, apostle the use of a aggregate of two or added altered classes of anti-malarial drugs to activity the disease. Patients should anon be transferred to the accomplished akin of affliction available. Claret glucose levels should be arrested consistently abnormally in children, abundant women and in the acutely ill patients.


Personal precautions aimed at abbreviation acknowledgment to mosquitoes (wearing continued sleeves and trousers) blockage central afterwards dusk, mosquito nets sprayed with insect repellant and chemoprophylaxis. Travelers are brash to activate demography malaria prophylaxis one anniversary afore biking and abide for 4 weeks afterwards return.

Word count: 235

Influenza Virus Structure

Image fatigued from Molecular expressions. [Online] Accessible at: < http://micro.magnet.fsu.edu/cells/viruses/influenzavirus.html>

Influenza is an RNA virus with a anecdotal genome. Affliction epidemics and endemics activity from the A-C virus groups.

Infection and spread

Influenza is transmitted via the respiratory amplitude advance from being to being through coughs and sneezes. It can additionally be advance by affecting an adulterated apparent and again affecting the eyes or mouth. Someone can be communicable alike afore they accept amorphous to appearance symptoms.

Influenza VaccineImage fatigued from Quick flu analytic tests. [Online] Accessible at: < http://www.geldin.com/wp-content/uploads/2013/12/Flu-sumptoms.jpg>


Symptoms are agnate to the accepted algid admitting the respiratory affection are added serious. Fever, apathy and myalgia are additionally accepted features.


Patients are brash to breach at home and accumulate hydrated and balmy and to acquaintance their GP if complications occur. New treatments such as the neuraminidase inhibitor oseltamivir may abate the continuance of symptoms.


A vaccine is accessible but it is alone able adjoin ahead abandoned strains. The vaccine is accordingly alone offered to those in aerial accident groups, i.e asthmatics, the aged and those with cardiac disease. Vaccines can account the accommodating to ache from affection of the flu admitting they are not activity to be as astringent as a abounding absolute flu virus infection.


“How does the anatomy avert itself adjoin bacilli which account communicable diseases?”

Our bodies are consistently beneath attack, every additional of everyday, our allowed systems do not rest. In adjustment for bacilli to access the anatomy they charge aboriginal appointment a basal of concrete and biochemical barriers through alive or acquiescent means.

Our aboriginal curve of defence from invasive bacilli accommodate the covering and keratinocytes of the skin. Alternative concrete barriers accommodate close membranes which band all of the body’s cavities which appear in to acquaintance with the accessible environment, such as the respiratory, gastro-intestinal and urogenital tracts. Beaker beef aural the close film epithelium bury an estimated 4 litres of close a day. In the respiratory amplitude the close accessories inhaled bacteria, fungi and alternative particles. Additionally aural the respiratory amplitude are millions of hairs (cilla) lining the airways, which advice to accumulate the passageways bright of debris. Mucosal surfaces of the clammy epithelium acquiesce the barter of molecules aural the ambiance whilst additionally afraid microbial invasion. The urinary amplitude itself is a concrete barrier to bacilli in a agnate way the respiratory amplitude is, it expels in an apparent movement. Urination works to arrest the movement of bacilli from the ambiance up into the kidneys and bladder. The abrasion activity of tears and saliva anticipate adapter of bacilli to the epithelial surfaces.

Our bark additionally has a role as a actinic barrier adjoin bacilli as diaphoresis glands bury oils, some of which are hardly acerb which arrest the advance of some bacteria. The stomach, urinary amplitude and breach ducts additionally comedy a aeon in the actinic barrier as they all accept antimicrobial properties, enzymes which breach bottomward bacilli to advice accumulate these areas chargeless from infection.

Once bacilli accept penetrated our aboriginal concrete curve of defence they are met by our congenital allowed system, our additional band of defence, which we are built-in with. An archetype of your congenital allowed arrangement at assignment is back you cut yourself and apprehension in a few hours that the armpit of the cut is red and swollen. This is a assurance that white claret beef or leukocytes accept rushed to the site, to advice activity any infections and activate the healing action of the damaged tissue. Leukocytes convoying the tissues and organs of the anatomy via the aqueous and claret circulatory systems like the soldiers of the allowed system. The best baneful of these beef is alleged a macrophage. They’re sole purpose is to chase and abort bacteria. They don’t aloof appear aloft bacilli in the anatomy the accept sensors or receptors which are acquainted to recognise “danger molecules”.

Lymphocytes are the beef circuitous in the adaptive allowed response, accurately alleged T beef and B cells. The adaptive allowed arrangement is a defence arrangement that can acclimate to assure us adjoin about any invader. There are three capital types of T cells, analgesic T cells, accepted as CTLs, abettor beef and authoritative T cells. A ample basal of T beef are produced in the primary lymphoid organs/tissues, acquired from stems beef in the cartilage marrow. Each T corpuscle has receptors specific for alone one antigen. T-cells which survive the alternative action drift to the borderline lymphoid tissues area they complete their anatomic maturation and accommodate aegis adjoin advancing microbes. B beef advance from hemopoietic axis beef primarily in the micro- ambiance of the foetal alarmist and, afterwards bearing in the cartilage marrow. There are two kinds of B beef B1 and B2. B & T beef are alleged by specific antigens to go on to booty allotment in an allowed response. This action of alternative is alleged the clonal selection. Back B beef are activated by an antigen, sometimes with T beef advice (helper cells), they accumulate and complete into anamnesis beef or claret cells. Cytoxic T-cells or CTL’s comedy an basic role in killing virus adulterated cells. They absolution perforin and granzymes on to the apparent of the ambition beef to abet absolute corpuscle afterlife (apoptosis). T beef are not accomplished at recognising and so responding to chargeless antigen. They can alone see an antigen back it is presented to them. This action is alleged antigen presentation and is facilitated by carrier molecules, such as MHC’s (Major histocompatability circuitous proteins).

An antigen that can account an allergic acknowledgment is alleged an allergen. During an allergic reaction, histamines and alternative chemicals are appear from mast corpuscle granules, which access capillary permeability so that aqueous escapes from the capillaries in the tissue. This is the acumen you get a aqueous adenoids and adulterated eyes back you accept an allergic reaction. Histamine binds to two types of receptors on ambition beef H1 and H2. Afterwards bounden to H receptors, histamine induces abbreviating of bland muscle, increases vascular permeability and close beard by beaker cells. Via H2 receptors, histamine increases belly secretion, decreases advocate absolution by basophils and mast cells.

Word count: 816


Natural (Innate)

Acquired (Adaptive)


Acquired through the foetus during development

Used to activity adjoin microbes

Some antibodies transferred to the growing foetus through the placenta

Also acclimated to activity bacilli and antigens



Defends adjoin any advancing antibody aloft exposure

Doesn’t advance afterward acknowledgment to a pathogen

Rapid acknowledgment to pathogens

First acknowledgment generates abiding anamnesis cells

Acquired throughout life, can be bogus due to vaccination.

Responds to specific antigens on additional exposure

Immunity increases the added it is apparent to a pathogen

Response alone activated already specific T beef accept been presented to a specific antigen, acceptation the acknowledgment is delayed.

Has no immunological memory

Word count: 103





Acts anon and eliminates bacilli afore it is able to account ache to the host

Antibodies are transferred to the foetus via the placenta or colostrum

Immunity can appear from a anesthetic application antibodies admitting this is alone abbreviate lived


Antibodies or lymphocytes are generated as a absolute aftereffect of infection

Long abiding immunological memory

Immune arrangement responds anon as a antibody enters the body

Short lived immunization consistent from the alteration of antibodies.

Word: 79

Word count:182/200


Anon, BBC, 2014. Defending adjoin infection. [Online] Accessible at: http://www.bbc.co.uk/schools/gcsebitesize/science/aqa_pre_2011/human/defendingagainstinfectionrev1.shtml [Accessed 2nd Feb 2015]

Food U.S. Aliment and Drug Administration http://www.fda.gov/Food/FoodborneIllnessContaminants/CausesOfIllnessBadBugBook/ucm070492.htm

Alberts B, 2002. Introduction to Bacilli [Online] Accessible at: http://www.ncbi.nlm.nih.gov/books/NBK26917/ [Accessed 2nd Feb 2015]

Darling, D, 2013. Bacteria. [Online] Accessible at: http://www.daviddarling.info/encyclopedia/B/bacteria.html [Accessed 2nd Feb 2015]

Todar, K, 2012. Bacterial anatomy in affiliation to pathogenicity. [Online] Accessible at: http://textbookofbacteriology.net/structure.html [Accessed 2nd Feb 2015]

Yager, R, 1996. Protozoa: Structure, classification, Advance and development. [Online] Accessible at: http://www.ncbi.nlm.nih.gov/books/NBK8325/ [Accessed 3rd Feb 2015]

Warrell, D, 2012. Oxford Textbook of Medicine: Infection. Oxford, Uk, Oxford University Press. P365-71

Inglis, TJ 2003. Microbiology and Infection. London, UK, Churchill Livingstone P91-2

Image. Illustrator unknown. Activity aeon of the malaria parasite. [online] Accessible at:http://en.wikipedia.org/wiki/File:Life_Cycle_of_the_Malaria_Parasite.jpg [Accessed 4th Feb 2015]

World bloom organisation, 2002. Prevention of hospital-acquired infections. [online] Accessible at: http://www.who.int/csr/resources/publications/whocdscsreph200212.pdf [Accessed 9th Feb 2015]

Anon. 2009. Proper duke abrasion tips to anticipate infection. [Online] Accessible at: https://coolrain44.wordpress.com/2009/07/24/proper-hand-washing-tips-to-prevent-infection/ [Accessed 10th Feb 2015]

Anon, 2007. Immunology Lectures. [Online] Accessible at: http://www.medicine.tcd.ie/physiology/assets/docs/archived%2008_09/lecturenotes/Tuffery07/JS_DipEx/11.Immunology2.pdf [Accessed 19th Feb 2015]

Cite This Work

To export a reference to this article please select a referencing stye below:

Reference Copied to Clipboard.
Reference Copied to Clipboard.
Reference Copied to Clipboard.
Reference Copied to Clipboard.
Reference Copied to Clipboard.
Reference Copied to Clipboard.
Reference Copied to Clipboard.

Order a Unique Copy of this Paper