Actinomycetes are a group of bacteria that are responsible for causing various diseases in humans. The set of diseases caused by actinomycetes include tuberculosis, leprosy, and diphtheria.

Tuberculosis:
- Tuberculosis is a highly contagious bacterial infection caused by the actinomycetes bacteria, Mycobacterium tuberculosis.
- It primarily affects the lungs but can also spread to other parts of the body.
- Symptoms of tuberculosis include persistent cough, chest pain, weight loss, fever, and night sweats.
- The bacteria spread through the air when an infected person coughs or sneezes, and it can be transmitted to others who inhale the bacteria.

Leprosy:
- Leprosy, also known as Hansen's disease, is caused by the bacterium Mycobacterium leprae.
- It primarily affects the skin, nerves, and mucous membranes.
- Leprosy is a chronic disease that progresses slowly and can cause disfigurement and nerve damage if left untreated.
- Symptoms of leprosy include skin lesions, numbness or loss of sensation, muscle weakness, and eye problems.
- The bacteria spread through respiratory droplets from an infected person or through prolonged close contact.

Diphtheria:
- Diphtheria is a bacterial infection caused by Corynebacterium diphtheriae, an actinomycetes bacterium.
- It primarily affects the throat and upper respiratory tract.
- Diphtheria can cause a thick, grayish coating in the throat, which can lead to breathing difficulties.
- Other symptoms include fever, sore throat, swollen glands, and weakness.
- The bacteria spread through respiratory droplets from an infected person or through contact with contaminated objects.

Pertussis, tetanus, and typhoid are not caused by actinomycetes bacteria. Pertussis, also known as whooping cough, is caused by the bacterium Bordetella pertussis. Tetanus is caused by the bacterium Clostridium tetani, and typhoid is caused by the bacterium Salmonella typhi.

In conclusion, the set of diseases caused by actinomycetes include tuberculosis, leprosy, and diphtheria. These bacterial infections can have significant health implications if not diagnosed and treated promptly.