Classification of human disease

Classical classification of human disease derives from the observational correlation between pathological analysis and clinical syndromes. Today it is preferred to classify them by their cause if it is known. A chief difficulty in nosology is that diseases often cannot be defined and classified clearly, especially when the cause or pathogenesis is unknown. Thus diagnostic terms often only reflect a symptom or set of symptoms.

Malaria is a mosquito-borne infectious disease caused by the bite of female Anopheles mosquitoes, which spread infectious Plasmodium parasites into a host. The WHO estimates that in 2020 about 240 million people had malaria and about 627,000 of them died. A vaccine to prevent malaria is available; however, its variable efficacy underscores the need for new interventions. Britannica Quiz Medical Terms and Pioneers Quiz Who discovered the major blood groups? CTD The Comparative Toxicogenomics Database is a scientific resource connecting chemicals, genes, and human diseases.

​Information for individuals and families who are impacted by inherited conditions or birth defects, and for policymakers and health care providers. Information about public health policies, systems, and environments that promote health and aid in the prevention and management of chronic disease. In an infectious disease, the incubation period is the time between infection and the appearance of symptoms. The latency period is the time between infection and the ability of the disease to spread to another person, which may precede, follow, or be simultaneous with the appearance of symptoms.

Some viruses also exhibit a dormant phase, called viral latency, in which the virus hides in the body in an inactive state. For example, varicella zoster virus causes chickenpox in the acute phase; after recovery from chickenpox, the virus may remain dormant in nerve cells for many years, and later cause herpes zoster. Find relevant and reliable medical information on diseases and conditions

It is especially dangerous for people who are very young or old or who have other conditions such as heart disease or asthma. Some diseases, such as most forms of cancer, heart disease, and mental disorders, are non-infectious diseases. Many non-infectious diseases have a partly or completely genetic basis and may thus be transmitted from one generation to another.