The scourges of 21st century

1.- Explain the difference between epidemic, endemic and pandemic.

An epidemic is an outbreak of an infectious disease that spreads quickly infecting a large number of people. If the disease stays in a determinate geographic area, it’s called endemic. If the disease infects many countries at the same time, it’s called pandemic.

3.-Infectious agents are parasites that invade the body of a living being (host or guest) and reproduce inside or on it, causing tissue damage. But, who can be infectious agents? Characterise them and set examples.

Viruses. They are cellular parasites. They’re the smallest infectious agents and they are difficult to eliminate if you don’t destroy the cells in where they live. An example of a disease provoked by a virus is the flu.

Bacteria. They are prokaryotic pluricellular organisms and they can reproduce without invade other cells. An example of a disease provoked by a bacteria is the tuberculosis.

Protozoa and fungi. Protozoa are unicellular and eukariotic, and fungi can be pluricellular or unicellular. The sleeping sickness is a disease provoked by a protozoa and athlete’s foot is provoked by a fungi.


2. – Which of the following factors are responsible for increased human infectious diseases? For those factors that are responsible, explain why they are.

Invasión y destrucción de los bosques: si los agentes infecciosos se encuentran en un habitat y lo destruimos, hacemos que se tengan que buscar otro hábitat.
Grandes concentraciones urbanas: cuantas más personas hayan en una zona más se extiende la enfermedad. 
Gran movilidad (geográfica) de las personas: cuando una persona viaja a un país y es infectada, al viajar a otra área geográfica puede hacer que otras personas acaben contagiadas.
-Mutaciones en algunos microorganismos: producida por mutaciones que ocurren en los microorganismos, con eso pueden hacerse inmunes al antibiótico que les impedía reproducirse o los eliminaba.
Construcción de presas: por la destrucción de un habitat.
Falta de higiene corporal y alimentaria: por la falta de higiene corporal puedes atraer a gérmenes, y por alimentarse de alimentos que se encuentran en mal y pueden tener gérmenes infecciosos.

4.- Could Robert Koch have been able to prove that the flu is an infectious disease? Why?

No, he couldn’t have been able to prove that because the flu is a disease caused by a virus and with the optical microscope you can’t see viruses. In his time electronic microscope didn’t exist.

5.- Define the following concepts related to infections: source of infection, contagion, vector, reservoir.

Source of infection:  a living being infected by a pathogen germ.

Contagion: when the germs of a source of infection passes to a healthy organism by a direct contact.

Vector: an animal who transports germs.

Reservoir: animals who have infectious agents for human beings.

6.- When we say a person is immune to an infectious disease, what does it mean? How can a person get that immunity?

It means that this person can defeat the disease easily. This person can obtain immunity overcoming the disease for a first time so the next time he is infected, his immune system “remembers” how to eliminate the disease.

7.- Distinguish between vaccines, antibiotics and antivirals.

Vaccines: when we introduce in our body a full pathogen, or part of it, than isn’t able to cause the infection but can stimulate the reaction of the immune system.

 Antibiotics:  they are chemical substances that can kill bacteria or prevent their reproduction.

Antivirals:  they are intended to prevent viruses from infecting cells or to prevent viruses to be released after their reproduction so they can’t infect other cells.

8.- Why use antibiotics if it is not necessary favors the emergence of resistance?

Because you kill the bacteria that aren’t immune to the antibiotic, but if there are some of them that are immune, they will be the only ones left so all the bacteria in your body will be immune.

10.- Why flu vaccine must be taken every year? Why flu becomes a pandemic with high mortality every now and then?

Flu virus are constantly mutating so every year we’re infected by a different flu virus. Because sometimes the human flu virus exchange genes with other animal flu virus so the virus become more difficult to overcome.


9.- Differentiate between original drugs (patents) and generic ones. How pharmaceutical companies justify the continuance of the patents? Who benefits from the production and importation of generic drugs?

The only difference between patent and generic drugs it’s that the generic ones are distributed by any pharmaceutical company and the patents are distributed by the company that discover the drug. They justify the continuance of patents because they are the discoverers and they want all the earnings of the drug. The developing countries or poor countries because for them, it’s better to buy drug as cheap as possible.