Infectious diseases

Pathogen= An infectious agent that causes disease
Disease=When an organism suffers from an abnormal condition and its effectiveness is reduced
Infectious disease=A disease caused by a pathogen that can be transmitted
Non-infectious disease=A disease with a cause other than a pathogen, including genetic disorders and cancer

Cholera:

Causative agent= Vibrio Cholerae (there are many strains)

Affects= Small intestine wall (secreted choleragen damages the epithelium)

Symptoms= Severe diarrhoea, dehydration, weakness

Method of transmission= Waterborne, Lack of food sanitation, Due to human waste getting into the water supply 

Method of diagnosis= Microscopic analysis of faeces

Prevention and control:
Social=Awareness and education
Economic=Improve sewage control, provide chlorinated water 
Biological=Short-term vaccination, antibiotics for severe cases

Cure?= Salts and glucose given intravenously to rehydrate them

Measles:

Causative agent= Morbillivirus

Affects=Respiratory passages, lymph nodes, conjunctiva

Symptoms=Cough, chest cold, conjunctivitis, rash and fever (+child blindness)

Method of transmission=Airborne droplets (therefore highly infectious)

Method of diagnosis=Blood test, Saliva test

Prevention and control:

Social=Surveillance, encourage breast feeding

Economic=Provide vaccination

Biological=MMR Vaccination (need 93% immunity to prevent transmission), rarely affects <8yrs due to passive immunity

TB:

Causative agent= Mycobacterium Tuberculosis

Symptoms= Coughing blood, raking cough, chest pain, fever + sweating, weight loss (can cause meningitis/hunchback)

Affects=Macrophages, primarily in lungs, secondary in lymph nodes, bones and gut (Only 1 in 10 of those who have it become activated)

Method of transmission= Airborne (coughing/sneezing), uncooked meat, unpasteurised milk

Method of diagnosis=Sputum, Chest x-ray

Prevention and control:
Social= Prevent overcrowding, pasteurise milk, Destroy TB cattle
Economic= Contact tracing
Biological=Treated with drugs (6 month course of combination antibiotics), BCG vaccination

Global distribution=More prevelant in developing countries and poorly ventilated areas, becoming more of a problem due to worldwide travel

Cure?= Antibiotics

Malaria:

Causative agent= Plasmodium falciparum/vivax/ovale (many strains, some drug resistant, with different antigens that can conceal themselves within the cell)

Affects= Hepatocytes, Erthrocytes, brain

Symptoms= Fever, anaemia, headaches, shivering, muscle pain, sweating

Method of transmission= Vector (female anopheles mosquito)

Method of diagnosis= Blood test

Prevention:

1. Prevent reproduction of vector=Draining stagnant water or, cover it with oil, spray it with chemicals
2. Avoid being bitten by vector=nets, insect repellent, clothes
3. Stop parasite infecting us=Anti-malarial drugs 

Control= Vaccine development too slow to keep up with the different strains of the protoctist.

Global distribution= 90% of malaria deaths in sub-saharan Africa

HIV/AIDS:

Causative agent= Human immunodeficiency virus

Affects= T-helper lymphocytes, brain cells, doesn't kill you but makes you more vulnerable to other diseases

Symptoms:
HIV=flu-like
AIDS=opportunistic diseases, TB, pneumonia

Method of transmission= Unprotected sexual intercourse with an HIV positive person, sharing of contaminated needles, placenta, breast milk

Method of diagnosis= Blood test

Prevention and control:
Social=Education, public health measures, free condom programmes, contact tracing 
Economic=Widespread testing and blood donor screening can't be afforded in developed countries, needle exchange
Biological=Drug resistance, Blood donor screening

Global distribution=First reported in USA, Mainly now in sub-saharan Africa (34 million cases)

Cure?= No known cure but drug therapy can slow it down

Smallpox:

Causative agent= Variola

Method of transmission=Direct contact with infected bodily fluids

Symptoms= Visible marks on the skin

Cure?= 1977 smallpox became the first major disease to be eliminated from the globe due to the vaccination (the World Health Organization offered $1000 to the first person to report an active smallpox case)