Question

1) What is the most contagious type of pathogen: virus, bacteria, or parasite? Why?

2) How are pathogens transmitted?

3) How frequently do pathogens mutate and evolve?

Answer 1

1. It depends. The overall contagiousness of a disease includes following factors:

• how many people in the population are susceptible to the disease
• the amount of time an infected person is contagious
• how many people an infected person is likely to come into contact with
• how the disease is transmitted

Not all bacterial pathogen are contagious. The example of bacterial infections which are contagious are:

a. Whooping cough, or pertussis, is a very contagious respiratory illness. The bacteria that causes it can be expelled in respiratory droplets that are formed when an infected person coughs or sneezes.

b. Impetigo is a very contagious skin infection. The infection can be acquired by direct skin-to-skin contact with an infected person.

Example of viral infection which are contagious are:

a. Measles, an airborne viral disease, is the most contagious infectious disease. A person with measles is able to infect anywhere between 12 to 18 additional people in a susceptible population.

b. In contrast to this is Ebola, a viral disease that’s transmitted via contact with the bodily fluids of an infected person. Someone with Ebola may infect about two additional susceptible people.

The overall contagiousness of a disease varies. However, there are more viral infections that are contagious comparitively. Also, the virus is never beneficial for the host. But in case of bacteria and parasite they may prove good for the host.

2. The transmission of pathogens can be divided in 5 main routes: direct contact, fomites(indirect contact), aerosol(airborne), oral(ingestion) and vectoeborne.

3. Again it depends. Some pathogens can mutate and evolve faster than other. For example, influenza virus. It causes seasonal cold and every year a new strain emerges.