Infection 1: Introduction to infection Flashcards
What are the organisms that cause infection
- Helminths (Biggest)
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- Insects |
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- Protozoa |
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- Fungi |
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- Bacteria |
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- Viruses |
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- Prions (Smallest)Example of helminths
Tapeworm
Example of insects
Fleas
Example of Protozoa
Malaria
Example of fungi
Candida
Example of bacteria
Staphylococci
Example of virus
Influenza
Example of prions
Kuru
What are the most common infections
Bacterial and viral
What is a parasite
Organism which depends on another for its survival to the detriment of the host
What are traditional medical parasites
- Helminths
- Insects
- Protozoa
Where do endoparasites live
Inside body
Where do ectoparasites live
Outside body
What are the major illnesses that endoparasites cause
- Helminths
- Protozoa
What are the minor illnesses that ectoparasites cause
- Fleas
- Lice
- Bed bugs
- Ticks
Describe Protozoa
- unicellular
- too small for naked eye
- complex lifecycle, involves more than 1 host
What are the two types of Protozoa
- Amoebae
- Sporozoa
Give an example of sporozoa
Plasmodium falciparum
Give an example of amoebae
Entamoeba histolytica
What does entamoeba histolytica do
- invades large bowel lining
- causes dysentery
What are the symptoms of dysentery
- abdominal cramps
- bloody diarrhoea
How is entamoeba excreted and spread and what increase its risk
With faeces
Contaminated food & water
Poor hygiene
Give an example of sporozoa
Plasmodium falciparum
Where does plasmodium falciparum live and what does it infect
Lives in humans and mosquitoes
Infects red blood cells & liver
What a re the symptoms of malaria
- Fever
- Headache
- Joint pains
What a re the complications of malaria
- Kidney failure
- Coma
- Brain problems
- Death
What is the risk of malaria
Geographical
Describe helminths
- complex organisms
- some complex life cycles with more than one host
How many types of worms are there
- Cestodes
- Trematodes
- Nematodes
Describe cestodes
- segmented
- flat
Describe trematodes
- unsegmented
- flat
Describe nematodes
- cylindrical
- digestive tract with lips, teeth and anus
Give an example of cestodes (tapeworms)
Toenia saginata
Describe toenia saginata
- intestinal parasite of humans
- tiny cysts on beef meat
- ingested by humans
Heat are the symptoms of toenia saginata
Largely asymptomatic
- abdominal pain
- malnutrition
What is the diagnosis foe toenia saginata
- Patience
- Stool microscopy for eggs
Who is the obligatory host for toenia saginata
Who is the intermediate
Human
Cattle
Give an example of trematodes (flukes)
Schistosomia haematobium
What does schistosomia haematobium cause
- Infection of veins around bladder
- Bladder inflammation
- Bleeding into urine
Diagnosis for schistosomia haematobium
Urine microscopy for eggs
Intermediate host for schistosomia haematobium
Freshwater snail
Give an example of ectoparasites
Bedbug
Example of bedbug
Cimex lectulsrius
Symptoms of bedbug
- Itchy rash after bite
- can transmit other infections
What are the forms of fungal infections
- Yeasts: single cells which bud
- Moulds: filamentous strands
What are superficial fungal infections
- Tinea pedis (athlete’s foot)
- Tinea corporis (ringworm)
Give an example of severe invasive fungal infection
Cryptococcus neoformans
What does cryptococcus neoformans do
Infect patients with failing immune system —> low resistance
What does cryptococcus neoformans cause
- meningitis
- headache
- neck stiffness
- confusion
- coma
- death
What diseases is bacteria responsible for
- Pneumonia
- UTI
- Meningitis
- Cellulitis (skint and subcutaneous tissue infection)
- Cholecystitis (gall bladder infection)
- Diverticulitis (bowel infection)
- Appendicitis
What shapes do bacteria take
- Round (coccus)
- Rod (Bacillus)
- Grouping (clusters, chains apirs)
How do some bacteria differ in structural composition
Some retain violet crystal stain
Gram positive colour
Purple
Gram negative colour
Pink (can’t hold stain)
Give an example of bacterial infection
Streptococcus pneumonia
Describe appearance of streptococcus pneumonia
- gram-positive
- diplococci
What does streptococcus do
- colonise nose & throat
- invades lungs —> pneumonia
What are symptoms of streptococcus
- cough
- dirty septum
- chest pain
- breathlessness
- fever
- blood stream infection
- meningitis
- death
What are the different kinds of viral infections
- Acute
- Chronic
- Latent
What happens in acute viral infection
- norovirus infects host for days
- diarrhoea & vomiting
What happens in chronic viral infection
- hep C —> liver inflammation for years
What happens in latent viral infection
Herpes dormant for decades —> activated —> causes disease
Example of virus that can cause latent infections
Varicella zoster
Varicella zoster virus causes
Chickenpox
Characteristics of chickenpox
- rash
- fever
Where are latent virus become dormant
Nerve roots
What does Epstein-Barr virus do
- mild illness
- infects B cells
- epithelial cells of nose and mouth
- latent lifetime infection
How common is Epstein-Barr virus
90% of UK get it
What cancers does Epstein-Barr virus contribute to
- Nasopharyngeal carcinoma
- Lymphoma
What are prions
- Proteinaceous Infectious particles
- Lack nucleic acids (not living)
How do they cause damage
- abnormal—> accumulate in neural tissues
- abration
- very difficult to destroy
Name 3 prion diseases
- CJD
- Variant CJD
- Kuru
What is CJD
Creutzfeldt-Jakob disease
Describe CJD
- rare
- foetal
- degenerative neurological disease
How is CJD transmitted
- human growth hormone
- surgical instruments
- corneal grafts
Where does variant CJD occur
Young adults
Where is CJD thought to be driven from
BSE
How is kuru spread
Cannibalism, esp brains of relatives
