1. Tuberculosis

1. Causative agent: Mycobacterium tuberculosis
2. Method of spread: Air borne
3. Signs and symptoms: Small round lesions in the lung tissue, weight loss, cough (sometimes containing blood), loss of appetite.
4. Prevention and control: Vaccination with BCG vaccine.

2. Gonorrhea

1. Causative agent: Neisseria gonorrhea or gonococcus bacterium.
2. Method of spread: Sexual intercourse with an infected person
3. Signs and symptoms: In women discomfort in the urethra and a slight discharge. In males an itching and burning sensation when urinating and a yellow discharge of pus from the penis.
4. Prevention and  control:

-Abstinence.

-Avoid sexual promiscuity.

-Males and females should use condoms during sexual intercourse with infected persons.

-By treating diagnosed cases.

3. Cholera

1. Causative agent: Vibrio cholera
2. Method of spread: Water and food borne
3. Signs and symptoms: Vomiting, large quantities of watery diarrhea containing little mucus.
4. Prevention and control:

-Supply of safe clean water.

-Hygienic disposal of feaces.

-Proper covering of water and treatment of sewage

-Hygienic handling and preparation of food

ECONOMIC IMPORTANCE OF BACTERIA

1. Useful Effects

-Saprophytic bacteria help to increase soil fertility

- The are a source of antibiotic e.g. Streptomycin from streptomyces bacteria

- Some bacteria help in the production of vitamin K from roughage e.g Escherichia Coli present in the colon of man

- Some bacteria present in the stomach secret cellulose which digest cellulose to glucose.

- Nitrogen fixing bacteria in the soil increase soil fertility by converting atmospheric nitrogen to soil nitrates

-Some are used in the industry for the fermentation of milk to yoghurt e.g lac to bacillus

- Bacteria are used in the breakdown of sewage

b) Harmful effects

-Parasitic bacteria cause diseases to nian e.g. cholera, typhoid, gonorrhea.

- Some bacteria cause food spoilage.

- Some bacteria kill animals which are of economic importance to man e.g. anthrax.

- Denitrifying bacteria decrease soil fertility by breaking soil nitrates to atmospheric nitrogen