Disease Process

There are four main types of disease: pathogenic disease, deficiency disease, hereditary disease, and physiological disease;

1. Pathogenic Disease

A pathogen is a biological agent, or germ, that causes disease to its host by interrupting normal body processes. Bacteria, viruses, fungi and parasites are all common types of pathogens that can cause pathogenic, or infectious, diseases. Below are two examples of a pathogenic disease

  • Trichinellosis

Trichinellosis, also called trichinosis, is an infection caused by eating raw or undercooked meat that is infected with the larvae of the worm Trichinella. Trichinella is most often found in wild animals that eat meat, but may also be found in domestic pigs, according to the Centers for Disease Control and Prevention. Initial symptoms of trichinellosis include nausea, diarrhea, fatigue, vomiting, fever and abdominal pain. As the infection progresses, more serious symptoms, such as headache, chills, cough, muscle ache and pain and itchy skin, may develop. Severe cases of trichinellosis cause heart problems, breathing difficulties and an inability to control muscle movement. These severe cases can result in death. Trichinellosis is treated with a series of medications.

  • Cellulitis

Cellulitis is a skin infection caused by the bacteria streptococcus or staphylococcus. Most commonly, the bacteria enter the body through a wound or open area on the skin, but can also gain access to the body through an insect bite. Cellulitis can occur anywhere on the body, but is most often seen on the lower leg, according to Mayo Clinic. Symptoms of cellulitis include redness, swelling, tenderness, pain, warm skin and fever. Treatment of cellulitis consists of an oral antibiotic that must be taken for 14 days. If left untreated, cellulitis can spread and cause a life-threatening infection in the body.

More Examples

2. Deficiency Disease

A disease, such as rickets or scurvy, that is caused by a dietary deficiency of specific nutrients, especially a vitamin or mineral. The disease may stem from insufficient intake, digestion, absorption, or utilization of a nutrient.

  • Rickets

Rickets is defined as a deficiency of vitamin D, calcium, or phosphate, with several various types.


  • Scurvy

Scurvy is caused by a diet that lacks vitamin C (ascorbic acid). Patients develop anemia, debility, exhaustion, edema (swelling) in some parts of the body, and sometimes ulceration of the gums and loss of teeth.