Infectious and non-infectious diseases

Explain the fundamental difference between an infectious disease and a non-infectious disease, and classify the following into the two groups: flu (influenza), diabetes, tuberculosis, asthma, measles, high blood pressure (hypertension).

Explain what contagion is and what difference there is between having been infected and having developed the disease.

Cardiovascular diseases are non-infectious, yet they are closely related to lifestyle habits. Explain which modifiable risk factors favour them and propose four preventive measures that a young person can adopt.

Name the four main types of agents that cause infectious diseases (viruses, bacteria, fungi and protozoa) and cite one disease caused by each type.

Explain what a microorganism is and reason, with an example, why not all microorganisms are harmful to humans.

A student returns from a trip to a tropical area and a few days later is diagnosed with malaria. A group of families asks the school management not to allow the student to attend classes for two weeks "out of fear that they will infect others by coughing or sharing school supplies."

1. a) Based on the type of microorganism causing it and its transmission route, write a scientific explanation to reassure the families, justifying why direct transmission between classmates in the classroom is biologically impossible.
2. b) If a plague of common mosquitoes (Culex pipiens) were to proliferate in the high school gardens, would there be a risk of them biting the infected student and transmitting malaria to the rest of the school? Justify your answer by applying the concept of a specific biological vector.

In the diagram, a sick person (left, surrounded by microorganisms) can transmit their infection to a healthy person (right) along three routes labelled with ?. Write the name of the transmission route that each path represents and give an example of a disease for each one.

Name three routes by which infectious diseases are transmitted and cite one disease transmitted by each one.

A class of 24 pupils goes on a field trip and the next day 6 classmates fall ill with gastroenteritis after sharing sandwiches. Calculate what percentage of the class fell ill, explain which transmission route is the most likely, what hygiene measures would have prevented it, and why not everyone who ate necessarily fell ill.

In a flu outbreak at a school with $400$ students, $60$ become infected in the first week. Without preventive measures, the number of weekly infections doubles; with measures (hand hygiene, ventilation, and staying at home with symptoms), it only increases by half each week. Calculate how many new infections there would be in the second week in each scenario, compare the evolution of the outbreak in both cases, and reason why it is said that the measures "flatten the curve" even if they do not prevent all infections.

Explain what the risk factors of a disease are and classify these examples into modifiable and non-modifiable: age, diet, smoking, genetic make-up, sedentary lifestyle.

Tooth decay is one of the most common and, at the same time, most preventable infectious diseases. Explain which bacteria cause it, which food favours their action on the teeth, and which three habits prevent it.

A patient who has been prescribed antibiotics for 8 days for bacterial pharyngitis decides to stop taking them on the fourth day because they no longer have a fever or pain, arguing: "If I already feel fine, the fewer pills I take, the less my body will get used to the medication and the better it will respond in the future." Identify the two scientific errors in their reasoning (one regarding which organism resistance acts upon and another about what happens to the population of bacteria still remaining in their throat) and justify, in terms of natural selection, why stopping the treatment early increases the risk of a relapse with bacteria that are harder to eliminate.