Update: This is actually the same behavior as old Export utility. J Chron Dis 1959 9:385–93.While testing a migration today with one of our clients, I figured out that schema export using Data Pump doesn’t capture public synonyms on the objects in this schema. On the estimation of the incubation period in malignant disease. Natural history and management of early HIV infection. The challenge to public health workers is that these carriers, unaware that they are infected and infectious to others, are sometimes more likely to unwittingly spread infection than are people with obvious illness.
However carriers may also be persons who appear to have recovered from their clinical illness but remain infectious, such as chronic carriers of hepatitis B virus, or persons who never exhibited symptoms. Persons with measles, hepatitis A, and several other diseases become infectious a few days before the onset of symptoms. Frequently, carriers are persons with incubating disease or inapparent infection. Such persons who are infectious but have subclinical disease are called carriers. Unfortunately, persons with inapparent or undiagnosed infections may nonetheless be able to transmit infection to others. Many additional cases may be too early to diagnose or may never progress to the clinical stage. Virulence refers to the proportion of clinically apparent cases that are severe or fatal.īecause the spectrum of disease can include asymptomatic and mild cases, the cases of illness diagnosed by clinicians in the community often represent only the tip of the iceberg. Pathogenicity refers to the proportion of infected individuals who develop clinically apparent disease. Ultimately, the disease process ends either in recovery, disability or death.įor an infectious agent, infectivity refers to the proportion of exposed persons who become infected. This range is called the spectrum of disease. In others, the disease process may result in illness that ranges from mild to severe or fatal. In some people, however, the disease process may never progress to clinically apparent illness. Most diagnoses are made during the stage of clinical disease. The onset of symptoms marks the transition from subclinical to clinical disease. Most screening programs attempt to identify the disease process during this phase of its natural history, since intervention at this early stage is likely to be more effective than treatment given after the disease has progressed and become symptomatic. Table 1.7 Incubation Periods of Selected Exposures and DiseasesĪlthough disease is not apparent during the incubation period, some pathologic changes may be detectable with laboratory, radiographic, or other screening methods. The latency period for leukemia to become evident among survivors of the atomic bomb blast in Hiroshima ranged from 2 to 12 years, peaking at 6–7 years.( 44) Incubation periods of selected exposures and diseases varying from minutes to decades are displayed in Table 1.7. For example, the typical incubation period for hepatitis A is as long as 7 weeks. Even for a single disease, the characteristic incubation period has a range. This period may be as brief as seconds for hypersensitivity and toxic reactions to as long as decades for certain chronic diseases.
During this stage, disease is said to be asymptomatic (no symptoms) or inapparent. This stage of subclinical disease, extending from the time of exposure to onset of disease symptoms, is usually called the incubation period for infectious diseases, and the latency period for chronic diseases. For cancer, the exposure may be a factor that initiates the process, such as asbestos fibers or components in tobacco smoke (for lung cancer), or one that promotes the process, such as estrogen (for endometrial cancer).Īfter the disease process has been triggered, pathological changes then occur without the individual being aware of them. For an infectious disease, the exposure is a microorganism. The process begins with the appropriate exposure to or accumulation of factors sufficient for the disease process to begin in a susceptible host. Department of Health and Human Services 1992. Source: Centers for Disease Control and Prevention. Figure 1.18 Natural History of Disease Timeline
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