Question

1) What is a pandemic? Provide an example

2) Which are the four Koch’s postulates that must to establish “cause and effect relationship” for establishing contributory causes for communicable disease?

3) Define each of the following:

- Passive immunity

- Inactivated/live vaccines

- Herd immunity

4) Please explain the Reproduction Ratio. Use 3-4 sentences to do so

5) Which are the three factors that affect the ease in which communicable diseases are transmitted?

Answer 1

ANSWER 1) Pandemic is defined as a global outbreak of a disease. It is the worldwide spread of a new disease. HIV/AIDS and influenza is an example of pandemic outbreak.

ANSWER 2) The four Koch's postulates that is a must to establish cause and effect relationship for establishing contributory causes for communicable disease are:

• a micro organism or a pathogen must be present in all cases of disease.
• The microorganism or the athogen can be isolated from the disease host and can be grown in pure culture.
• This pathogen that is grown in pure culture must cause the disease when inoculated on a healthy, susceptible laboratory animal.
• The pathogen should be reisolated from the host and should be shown to be the same as origionally inoculated pathogen.

ANSWER 3) Passive immunity: Passive immunity is administration of antibodies into an unimmunized person from a immune subject to produce a temporary protection against the microbial agent or toxin. Example: immunity gained by admininstration of vaccines, immunity acquired naturally from mother to fetus via placenta by tramission of maternal antibodies.

Inactivated Vaccines: Its a type of vaccine which contains virus, bacteria or other pathogen that has been grown in cuture and then killed by using a method like heat or formaldehyde. Example: polio vaccine, influenza vaccine.

Live vaccine: These are the vaccines which are created by reducing the virulence of the pathogen but still keeping it alive. Live vaccines are the weakened form of the germ. Example : MMR, BCG vaccine.

Herd immunity: Herd immunity means the resistence developed against a particular infection among the unimmunized people when a large group of same population is vaccinated. It is an indirect protection from an infectious disease when a large group of population becomes immune to an infection and thereby providing protection to those who is not immune. Example: the outbreak of measles among the university students resulted in individuals who have been not protected by vaccines and escaped infection due to herd immunity.

ANSWER 4) The reproduction ratio of an infection can be thought as the number of cases one case generates on average over the course of its infectious period, or otherwise in an uninfected population. It helps to determine if the infectious disease can or cannot spread through the population.

ANSWER 5) The factors that help in easy transmission of communicable disease are:

• Infectious agent: are the pathogens like bacteria, virus or fungi which are responsible to cause infection
• Host or the reservoirs: They are the non living or human being where the infectious agent spread and cause infection.
• Mode of transmission: It is the route how an infectious agent infect the host. It can be direct like touch, sexual intercourse or indirect like airborne, waterborne etc