Infectious diseases
| English | Chinese | Pinyin |
|---|---|---|
| infectious disease | 传染病 | chuán rǎn bìng |
| pathogen | 病原体 | bìng yuán tǐ |
| transmissible | 可传播 | kě chuán bō |
| cholera | 霍乱 | huò luàn |
| malaria | 疟疾 | nüè jí |
| vector | 媒介 | méi jiè |
| tuberculosis | 结核病 | jié hé bìng |
| immune system | 免疫系统 | miǎn yì xì tǒng |
The enemy at the gates
- An infectious disease 传染病 is caused by a pathogen 病原体 — an organism that lives in or on a host and causes harm.
- These diseases are transmissible 可传播: the pathogen passes from one person to another.
- You need to know four key examples.
Infectious disease route lab
Classify disease cases by pathogen and route of transmission.
A pathogen is:
A pathogen causes an infectious (transmissible) disease — e.g. a bacterium, virus or protoctist.
Four diseases to know
| Disease | Pathogen | How it spreads |
|---|---|---|
| cholera 霍乱 | bacterium (Vibrio cholerae) | water/food contaminated with faeces |
| malaria 疟疾 | protoctist (Plasmodium) | bite of an infected mosquito (a vector 媒介) |
| tuberculosis 结核病 (TB) | bacterium (Mycobacterium) | airborne droplets from coughs/sneezes |
| HIV/AIDS | virus (HIV) | unprotected sex, infected blood, mother to baby |
Match each disease to its type of pathogen.
Pathogens come in several types — bacteria, viruses, protoctists and fungi all cause disease.
An organism that carries a pathogen from one host to another — like the mosquito for malaria — is a ______.
The mosquito is the vector that transmits the Plasmodium protoctist when it bites.
Cholera is caused by a bacterium and spreads through water or food contaminated with faeces.
Cholera (Vibrio cholerae) spreads via contaminated water/food — so clean water and sanitation prevent it.
Malaria is caused by a protoctist (Plasmodium) carried by:
The mosquito is the vector that transmits the Plasmodium protoctist when it bites.
Why HIV is so serious
- HIV infects and destroys certain white blood cells.
- These are the cells that defend the body, so HIV slowly weakens the immune system 免疫系统.
- This leads to AIDS, when the body can no longer fight off infections.
Mycobacterium tuberculosis (red rods) stained in a sputum sample
HIV weakens the body because it:
HIV destroys certain white blood cells, so the immune system weakens and AIDS can develop.
Pathogens and transmission
- Diseases are caused by bacteria, viruses, fungi and protoctists.
- They spread by direct contact or indirect routes (air, water, food, vectors) — hygiene and clean water break these routes.
Malaria spreads through a mosquito vector: the mosquito carries Plasmodium from person to person
A pathogen is not the same as the disease. The pathogen is the microbe; the disease is the harm it causes. The same pathogen can cause different symptoms in different people.
You've got it
- pathogen = organism that causes disease; infectious diseases are transmissible
- cholera (bacterium, dirty water), malaria (protoctist, mosquito vector)
- TB (bacterium, airborne droplets), HIV/AIDS (virus, sex/blood/mother-to-baby)
- HIV destroys white blood cells → weakens the immune system