Disease Incubation Period

One of the the aspects of prion disease that interests me most is its long incubation period. An incubation period is the time between the moment a person is infected with a pathogen and the moment a person starts displaying symptoms of disease. In the case of prion diseases, incubation periods can last three years. Incubation periods are vital to understand the epidemiological structure of disease. How can you trace the spread of disease if you do not know when the infection was contracted?

The incubation period is distinct from the contagious period, in which disease can be spread from organism to organism. As someone that works with children, I was curious about the differences between incubation periods in young and old people. It turns out that children have shorter incubation periods than adults (because their bodies are worse at fighting the illness) but that they have longer contagious periods. This reason, along with others, is why children tend to get more sick than adults.

To connect back to our class activity, I was confused about why children were getting the neurodegenerative illness. Often neurological symptoms are common in older adults who suffer from MS, Alzheimer’s, Parkinson’s, and ALS, so it was disturbing to me that kids were getting it. Certainly a strange case. I wondered about early onset Alzheimer’s, which is on the rise, for reasons that doctors do not know. This seems to highlight the importance of epidemiologists and the hard work that they have to do.

Here is a chart I found about the incubation and contagious periods of common illnesses!

http://en.wikipedia.org/wiki/Incubation_period 
http://www.childrensoscillo.com/features/healthy-kids/http://www.childrenshealthnetwork.org/CRS/CRS/pa_incubate_hhg.htm
                        Incubation 
  Disease             Period (days)    Contagious Period 
---------------------------------------------------------------
---------------------------------------------------------------
SKIN INFECTIONS 

Chickenpox                10 to 21    5 days before rash
                                      until all sores have
                                      crusts (5-7 days)

Hand, foot, and mouth      3 to 6     Onset of mouth ulcers
  disease                             until fever is gone

Impetigo (strep or staph)  2 to 5     Onset of sores until
                                      24 hours on antibiotic

Measles                    8 to 12    4 days before until 5
                                      days after rash appears

Meningitis                 3 to 6     Onset of symptoms and for
                                      1 to 2 weeks

Rubella (German measles)  14 to 21    7 days before until
                                      5 days after rash appears

Shingles (contagious      14 to 16    Onset of rash until
  for chickenpox)                     all sores have crusts
                                      (7 days) (Note: No
                                      need to isolate if
                                      sores can be kept
                                      covered.)

---------------------------------------------------------------
RESPIRATORY INFECTIONS 

Bronchiolitis              4 to 6     Onset of cough until
                                      7 days

Colds                      2 to 5     Onset of runny nose
                                      until fever is gone

Cold sores (herpes)        2 to 12    See footnote B

Coughs (viral)             2 to 5     Onset of cough until
                                      fever is gone

Influenza (Seasonal)       1 to 3     Onset of symptoms until
                                      fever is gone over 24 hours

Influenza (H1N1)           4 to 6     Onset of symptoms until
                                      fever is gone over 24 hours 
Sore throat, strep         2 to 5     Onset of sore throat
                                      until 24 hours on
                                      antibiotic

Sore throat, viral         2 to 5     Onset of sore throat
                                      until fever is gone