For Parvovirus B19 is true that:

Correct Answer: C

Rationale: The correct answer is C because Parvovirus B19 causes erythema infectiosum, also known as fifth disease. This virus primarily affects children and causes a distinctive red rash on the cheeks, arms, and legs. It is not associated with causing HBV (Hepatitis B Virus), AIDS, or measles. Parvovirus B19 specifically targets red blood cell precursors, leading to anemia in some cases. Understanding the characteristic clinical presentation and pathophysiology of the virus helps in selecting the correct answer.

Correct Answer: B

Rationale: Rationale: The correct answer is B. Viruses of the family Paramyxoviridae cause the formation of giant multinucleated cells called syncytia. This occurs when infected cells fuse together, resulting in large, multinucleated structures. This is a characteristic cytopathic effect of paramyxoviruses. Summary: A: Fine grained degeneration is not typically seen in paramyxovirus infections. C: Large cell degeneration with grape clustering of cells is not a typical cytopathic effect of paramyxoviruses. D: Paramyxoviruses do provoke a cytopathic effect, so this statement is incorrect.

Correct Answer: B

Rationale: The correct answer is B: abiogenesis. Spontaneous generation refers to the idea that living organisms can arise from non-living matter, which was disproven by Louis Pasteur. Abiogenesis specifically refers to the origin of life from non-living matter, making it synonymous with spontaneous generation. Biogenesis (A) is the principle that living organisms only come from other living organisms. Evolution (C) is the process of gradual change in species over time. Spontaneity (D) refers to happening without external cause and is not directly related to the concept of spontaneous generation.

Correct Answer: A

Rationale: The correct answer is A: Staphylococcus aureus. This bacterium causes food poisoning by producing enterotoxins that lead to symptoms like nausea and vomiting. Staphylococcus aureus can survive in various food items and multiply rapidly, producing toxins that are heat-stable. Clostridium botulinum causes botulism due to neurotoxins, not enterotoxins. Salmonella enterica causes gastrointestinal infections, not primarily food poisoning. Vibrio cholerae causes cholera by producing a toxin that leads to severe watery diarrhea and dehydration, not enterotoxins like Staphylococcus aureus.

Correct Answer: D

Rationale: The correct answer is D because all measures mentioned are important in preventing hospital-acquired infections. Isolating the source helps prevent the spread of infections. Isolating at-risk patients reduces their exposure. Increasing patient resistance to infections through proper hygiene and immunizations minimizes susceptibility. Each measure plays a crucial role in infection prevention, making all options correct.