Question 1

Which of the following best explains why measles is considered one of the most contagious diseases known to humans?

Accepted Answer

It can be transmitted by both droplet and airborne routes, and a single infected person can infect 12-18 others.

Question 2

A 7-year-old child presents with fever, cough, conjunctivitis, and a rash that started on the face and spread to the trunk. Koplik's spots are observed in the mouth. What is the most likely diagnosis?

Accepted Answer

Measles (Rubeola)

Question 3

Which of the following statements about immune amnesia following measles infection is correct?

Accepted Answer

Immune amnesia causes loss of preexisting immune memory and makes it difficult to establish new memory for 2-3 years.

Question 4

Which of the following is the primary vector for Borrelia burgdorferi, the causative agent of Lyme disease?

Accepted Answer

Hard ticks of the genus Ixodes

Question 5

A patient presents with an expanding red rash resembling a bull's eye at the site of a tick bite, along with fever and muscle aches. Which stage of Lyme disease is this?

Accepted Answer

Stage 1: Early Localized Lyme Disease

Question 6

Why is diagnosis of Lyme disease sometimes difficult in the early stages?

Accepted Answer

Antibodies against Borrelia are not detectable until more than 4-6 weeks after infection.

Question 7

Which of the following best describes the pathogenesis of infectious mononucleosis caused by Epstein-Barr virus (EBV)?

Accepted Answer

EBV infects epithelial cells of the throat and parotid glands, then invades B lymphocytes, spreading throughout the body.

Question 8

A 19-year-old college student presents with severe sore throat, fever, swollen lymph nodes, and extreme fatigue. Blood smear shows large, lobed B lymphocytes with atypical nuclei. What is the most likely diagnosis?

Accepted Answer

Infectious mononucleosis

Question 9

Which of the following is a key virulence factor of Plasmodium species that contributes to malaria pathogenesis?

Accepted Answer

Adhesins that allow adherence to cell receptors in both mosquito and human hosts

Question 10

Which genetic trait provides relative protection against severe and uncomplicated malaria?

Accepted Answer

Heterozygous sickle cell trait (HbS)

Question 11

A traveler returning from sub-Saharan Africa presents with cyclic fevers, chills, and anemia. Blood smear reveals ring forms inside erythrocytes. What is the most likely diagnosis?

Accepted Answer

Malaria

Question 12

Which of the following best explains why malaria is difficult to eradicate?

Accepted Answer

The reproductive cycle occurs within red blood cells, which lack MHC, allowing immune evasion.

Question 13

Which of the following is the most effective strategy for preventing measles outbreaks in a population?

Accepted Answer

Achieving at least 90-95% immunization coverage with the MMR vaccine

Question 14

A patient with a history of a tick bite develops multiple ringed rashes, arthritis, and facial paralysis (Bell's palsy) weeks later. What is the most likely explanation for these symptoms?

Accepted Answer

Immune system response to Borrelia burgdorferi infection

Question 15

Which of the following is a recommended first-line treatment for early-stage Lyme disease?

Accepted Answer

Doxycycline

Question 16

Which of the following statements about the epidemiology of malaria is correct?

Accepted Answer

Humans are the reservoir for human malaria, and the disease is endemic in over 100 countries.

Question 17

Which of the following best describes the mechanism by which the sickle cell trait confers resistance to malaria?

Accepted Answer

Heterozygous sickle cell trait alters hemoglobin, making red blood cells less hospitable to Plasmodium.

Question 18

Which of the following is a key reason why patients recovering from measles are at increased risk for secondary infections?

Accepted Answer

Measles causes immune amnesia, erasing preexisting immune memory and impairing new memory formation.

Question 19

A blood smear from a patient with malaria shows ring forms inside erythrocytes. Which stage of the Plasmodium life cycle is this?

Accepted Answer

Erythrocytic cycle

Question 20

Which of the following is NOT a recommended prevention strategy for Lyme disease?

Accepted Answer

Receiving the MMR vaccine

Microbial Systemic Diseases and Immune Interactions (Chapter 21): Measles, Lyme Disease, Mononucleosis, and Malaria

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