Microbes And Disease

Microbes and Disease Human pathogens

What are micro-organisms? ,[object Object],Bacteria (orange) on the tip of a pin. Magnification x1600 when the image is printed 10 cm high. The tip of the pin is approximately 20 µm across and the bacteria are around 5 µm long. ,[object Object]

[object Object],What are micro-organisms? Algae Protozoa Bacteria Fungi Viruses Illustration of microbes

What are micro-organisms? What does the word ‘microbe’ mean to you? To most people microbe only means……. ,[object Object],[object Object],[object Object],[object Object],INFECTION But….

Infection and disease ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],An infection does not always result in disease!

How do microbes reach us? ,[object Object],[object Object],[object Object],[object Object],[object Object],Source /reservoir of infection Mode of transmission HUMAN HOST represents the various barriers to infection e.g. the skin represents the target organ e . g . lungs Portal of entry Portal of exit

Mode of transmission Microbes can be transmitted by: Vertical • Placenta • Breast milk Vehicle borne • Air/dust • Food • Water • Fomites Vector borne • Internal • External Direct contact – person to person Horizontal • Kissing • Sexual intercourse • Sneezing less than 1 metre • Touching Indirect contact

Mode of transmission Direct contact – p erson to person Example: cold sore ,[object Object],[object Object],[object Object],A couple kissing. Cold sores on lip and mouth.

Mode of transmission Direct contact – person to person Example: cold sore ,[object Object],[object Object],Herpes simplex virus budding from the surface of a cell.

Mode of transmission Direct contact – person to person Example: syphilis ,[object Object],[object Object],[object Object],Interlocking gender symbols representing sexually transmitted diseases.

Mode of transmission Direct contact – person to person Example: syphilis ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],The bacteria that cause syphilis. Secondary syphilis rash.

Mode of transmission Direct contact – person to person Example: SARS ,[object Object],[object Object],[object Object],[object Object],Jets of droplets erupt from a man’s nose as he sneezes.

Mode of transmission Direct contact – person to person Example: SARS ,[object Object],[object Object],[object Object],[object Object],Routes of infection for SARS virus (spiky balls).

Mode of transmission Direct contact – person to person Example: gastroenteritis ,[object Object],[object Object],[object Object],[object Object],Human hand contaminated with colonies of bacteria (blue/pink patches).

Mode of transmission Direct contact – person to person Example: gastroenteritis ,[object Object],[object Object],[object Object],[object Object],Norwalk virus particles.

Mode of transmission Direct contact – person to person Example: German measles ,[object Object],[object Object],[object Object],[object Object],Eight week old fetus attached to its placenta by the umbilical cord. Vertical across the placenta or via breast milk

Mode of transmission Direct contact – person to person Example: German measles ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Mode of transmission Indirect contact – vehicle borne Example: tuberculosis (TB) ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Mode of transmission Indirect contact – vehicle borne Example: tuberculosis (TB) ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],A person with active TB will have the following symptoms that get more severe over time Mycobacterium tuberculosis bacteria.

Mode of transmission Indirect contact – vehicle borne Example: food poisoning ,[object Object],[object Object],[object Object],[object Object],Campylobacter jejuni bacterium.

Mode of transmission Indirect contact – vehicle borne Example: food poisoning ,[object Object],[object Object],[object Object],[object Object],[object Object]

Mode of transmission Indirect contact – vehicle borne Example: c ryptosporidiosis ,[object Object],Via water ,[object Object],[object Object],[object Object]

Mode of transmission Indirect contact – vehicle borne Example: c ryptosporidiosis ,[object Object],[object Object],[object Object],[object Object],Intestinal surface (orange) infected with C. parvum (round).

Mode of transmission Indirect contact – vehicle borne Example: athlete’s foot ,[object Object],[object Object],[object Object],[object Object],Fomite - a non-living object that can carry disease-causing organisms. Close-up of athlete’s foot infection.

Mode of transmission Indirect contact – vector borne Example: malaria ,[object Object],[object Object],[object Object],[object Object],A. gambiae feeding on human blood.

Mode of transmission Indirect contact – vector borne Example: malaria ,[object Object],[object Object],[object Object],[object Object],The passage of malaria through the human body.

Mode of transmission Indirect contact – vector borne Example: bacterial dysentery ,[object Object],[object Object],[object Object],External – mechanical Common house flies feeding.

Part 3 HOW DO MICROBES GET IN?

Portals of entry ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Portals of entry Respiratory tract Example: influenza ,[object Object],[object Object],[object Object],[object Object],[object Object],The respiratory tract.

Portals of entry Respiratory tract Example: influenza ,[object Object],[object Object],[object Object],[object Object],Influenza virus particles.

Portals of entry Gastrointestinal tract Example: cholera ,[object Object],[object Object],[object Object],[object Object],The gastrointestinal tract.

Portals of entry Gastrointestinal tract Example: cholera ,[object Object],[object Object],[object Object],[object Object],Vibrio cholerae bacteria.

[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Portals of entry Urogenital tract Example: cystitis Artwork of an inflamed bladder (red) caused by cystitis.

Portals of entry Urogenital tract Example: cystitis ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Bacterial infection of the bladder. E. coli bacteria (yellow) on swollen epithelial cells (blue) lining the bladder.

Portals of entry Urogenital tract Example: Chlamydial infection ,[object Object],[object Object],[object Object],[object Object],[object Object],C. trachomatis bacteria (background) with the female reproductive tract superimposed.

Portals of entry Urogenital tract Example: Chlamydial infection ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Portals of entry Breaking the surface of the skin Example: tetanus ,[object Object],[object Object],[object Object],[object Object],[object Object],Splinter in the finger.

Portals of entry Breaking the surface of the skin Example: tetanus ,[object Object],[object Object],[object Object],[object Object],[object Object],Clostridium tetani bacteria.

Defending ourselves against microbes ,[object Object],[object Object],[object Object],T he body is protected by a complex system of defences that prevent assault from pathogeni c microbes.

Defending ourselves against microbes ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Non specific physical barriers ,[object Object],[object Object],[object Object],Cilia in the trachea rhythmically beating.

Non specific physical barriers ,[object Object],[object Object],[object Object],[object Object],E. coli bacteria (yellow) in the gut are part of the normal intestinal flora of humans.

Non specific chemical barriers ,[object Object],[object Object],[object Object],[object Object],The honeycombed sebaceous gland (light brown) produces sebum.

Non specific immune system ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Phagocytosis, a phagocyte (blue) engulfing a yeast cell (yellow).

Specific immune system ,[object Object],[object Object],Two antibodies bound to an antigen.

Specific immune system ,[object Object],[object Object],[object Object],[object Object],Antigens on the surface of a microbe.

Specific immune system ,[object Object],[object Object],[object Object],Antibody

Specific immune system ,[object Object],[object Object],[object Object],The person is protected from the disease through this natural immunity

Vaccination ,[object Object],[object Object],[object Object],[object Object],Vaccination

Vaccination ,[object Object],[object Object],[object Object],[object Object],Vaccine production.

What are antibiotics? ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Antibiotic drugs (discs) prevent the growth of bacteria (white) demonstrated by clear zones around the discs.

How do antibiotics work? ,[object Object],[object Object],[object Object],[object Object],Antibiotics acting on bacteria causing them to expand and burst.

Emergence of drug-resistant bacteria ,[object Object],[object Object],[object Object],[object Object]

Why has antibiotic resistance occurred? ,[object Object],[object Object],[object Object],[object Object],MRSA

How do microbes leave our body? ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Pus from an infected ear.

Conclusion ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Microbes And Disease

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Microbes And Disease