Explore how bacteria, viruses, fungi, protists and parasites cause infectious disease, using cholera, malaria, food poisoning and intracellular or extracellular infection evidence in IB Biology HL C3.2.1.
Outline the symptoms, mode of transmission and treatment of one named example of food poisoning.
symptom;
transmission;
treatment;
eg Salmonella food poisoning
symptoms: diarrhoea/fever/abdominal cramps/Reiter's syndrome.
transmission: by contact after poor personal hygiene/eating contaminated food (not properly cooked)/transferred from faeces of pets/from reptiles/poor kitchen hygiene/raw eggs/unpasteurised milk.
treatment: rehydration/lots of drinking/intravenous fluids/antibiotics.
Distinguish between intracellular and extracellular bacterial infection using Chlamydia and Streptococcus as examples.
| Intracellular (Chlamydia) | Extracellular (Streptococcus) |
|---|---|
| lives inside cells of host | lives outside host cells; |
| does not produce toxins/no toxins to irritate tissues/does not damage cells | produces toxins/damages cells; |
| host may not be aware of infection/asymptomatic | produces symptoms (sore throat) so host aware of infection; |
| not targeted by immune system / (usually) long-term infection | targeted by immune system / (usually) short-term infection; |
| sexually transmitted disease / infectious conjunctivitis | respiratory infection / pneumonia / skin infections; |