Question 38

Influenza in humans is caused by a virus.

Influenza is primarily caused by a virus, specifically the influenza virus, which is responsible for the seasonal flu outbreaks in humans.

A) Bacterium

Bacteria are distinct types of pathogens that can cause various infections; however, they do not cause influenza. Conditions such as strep throat or bacterial pneumonia are examples of bacterial infections, but they are unrelated to the viral nature of influenza.

B) Virus

Viruses are the correct type of pathogen that causes influenza in humans. The influenza virus infects the respiratory tract and is known for causing seasonal epidemics and occasional pandemics, which directly aligns with the question regarding the causative agents of influenza.

C) Fungus

Fungi are another category of pathogens that can lead to infections, but they do not cause influenza. Fungal infections typically affect areas like the skin, lungs, or other body systems, distinguishing them from viral infections such as the flu.

D) Protozoan

Protozoa are single-celled organisms that can cause diseases such as malaria and giardiasis, but they are not responsible for influenza. The influenza virus does not belong to this category of pathogens, further validating that protozoans are irrelevant in this context.

Conclusion

The correct answer is that influenza is caused by a virus, as this aligns with the scientific understanding of the disease's etiology. All other options represent different types of pathogens that do not contribute to influenza, reinforcing the distinction between viral infections and those caused by bacteria, fungi, or protozoa.