Common Epidemics, Their Causes and Prevention
Common Epidemics, Their Causes and Prevention MCQ Questions
13.
Prevention of malaria primarily involves:
A.
Avoiding contact with infected persons
B.
Vaccination with MMR vaccine
C.
Control of Anopheles mosquito breeding and use of insecticides/mosquito nets
D.
Drinking boiled water only
ANSWER :
C. Control of Anopheles mosquito breeding and use of insecticides/mosquito nets
Approach
The question asks about the primary methods for preventing malaria. Malaria is a vector-borne disease, meaning it is transmitted by an intermediate organism. Understanding the transmission cycle is key to identifying effective prevention strategies.
Step-by-step
- Identify the causative agent and vector: Malaria is caused by parasites of the genus Plasmodium, which are transmitted to humans through the bites of infected female Anopheles mosquitoes.
- Target the vector: Since mosquitoes are the vectors, controlling their population and preventing their bites are the most direct and effective ways to prevent malaria.
- Consider methods of vector control: This includes eliminating mosquito breeding sites (e.g., stagnant water), using insecticides to kill adult mosquitoes, and using physical barriers like mosquito nets to prevent bites.
- Evaluate the given options:
- A) Avoiding contact with infected persons: Malaria is not spread directly from person to person like a common cold.
- B) Vaccination with MMR vaccine: The MMR vaccine protects against Measles, Mumps, and Rubella, not malaria.
- C) Control of Anopheles mosquito breeding and use of insecticides/mosquito nets: This directly targets the vector and its life cycle, aligning with effective malaria prevention.
- D) Drinking boiled water only: This prevents water-borne diseases like cholera or typhoid, not vector-borne diseases like malaria.
- Conclude the most effective primary prevention: Based on the transmission mechanism, targeting the mosquito vector is the primary and most effective prevention strategy.
Correct Option:
C) Control of Anopheles mosquito breeding and use of insecticides/mosquito nets. This option directly addresses the transmission pathway of malaria by targeting the vector (Anopheles mosquito). Eliminating breeding sites reduces mosquito populations, while insecticides and mosquito nets prevent mosquito bites, thereby breaking the chain of transmission.
Incorrect Options
- A) Avoiding contact with infected persons — Malaria is not transmitted directly from person to person. It requires a mosquito vector to transfer the parasite.
- B) Vaccination with MMR vaccine — The MMR (Measles, Mumps, Rubella) vaccine protects against viral diseases and has no role in preventing malaria, which is caused by a parasite. While malaria vaccines are under development and some are approved, the MMR vaccine is not for malaria.
- D) Drinking boiled water only — Drinking boiled water is a measure to prevent water-borne diseases (e.g., cholera, typhoid) by killing pathogens in the water. It has no impact on preventing mosquito-borne diseases like malaria.
14.
Typhoid fever is caused by which bacterium?
ANSWER :
A. Salmonella typhi
Approach
The question asks to identify the specific bacterium responsible for causing typhoid fever. This requires knowledge of common bacterial diseases and their causative agents.
Step-by-step
- Recall the causative agents of various common bacterial diseases.
- Identify the bacterium specifically associated with typhoid fever.
Typhoid fever is a serious bacterial infection that can spread throughout the body, affecting many organs. It is caused by a specific type of bacterium.
Correct Option: A) Salmonella typhi
Salmonella typhi is the bacterium that causes typhoid fever. It is transmitted through contaminated food and water, primarily in areas with poor sanitation. The infection leads to symptoms like high fever, fatigue, headache, nausea, and abdominal pain.
Incorrect Options
- B) Shigella dysenteriae — This bacterium is the primary cause of shigellosis, also known as bacillary dysentery, which is characterized by severe diarrhea, fever, and abdominal cramps. It does not cause typhoid fever.
- C) Vibrio cholerae — This bacterium is responsible for causing cholera, an acute diarrheal illness that can lead to severe dehydration and is often transmitted through contaminated water sources. It is not the cause of typhoid fever.
- D) Escherichia coli — While some strains of Escherichia coli (E. coli) can cause various infections, including urinary tract infections, traveler's diarrhea, and food poisoning, it is not the bacterium that causes typhoid fever.
15.
Typhoid fever is primarily transmitted through:
A.
Contaminated food and water (fecal-oral route)
B.
Airborne droplets from infected persons
C.
Direct skin contact with infected persons
D.
Bite of female Anopheles mosquito
ANSWER :
A. Contaminated food and water (fecal-oral route)
Approach
The question asks about the primary mode of transmission for typhoid fever. To answer this, one needs to recall the common routes of transmission for various infectious diseases, specifically focusing on bacterial infections like typhoid.
Step-by-step
- Identify the causative agent: Typhoid fever is caused by the bacterium Salmonella Typhi.
- Recall common transmission routes for bacterial enteric infections: Many bacterial infections affecting the gastrointestinal tract are transmitted through contaminated food and water.
- Relate to typhoid fever: Salmonella Typhi is shed in the feces of infected individuals. If sanitation is poor, these bacteria can contaminate water sources or food, leading to new infections when consumed by others. This is known as the fecal-oral route.
- Evaluate the options: Compare this understanding with the given options to find the best fit.
Correct Option:
A) Contaminated food and water (fecal-oral route) is the primary mode of transmission for typhoid fever. The bacteria Salmonella Typhi are passed in the feces and urine of infected people. If these contaminated materials come into contact with food or water supplies, the bacteria can be ingested by others, leading to infection. This route is particularly prevalent in areas with inadequate sanitation and hygiene.
Incorrect Options
- B) Airborne droplets from infected persons: This is the primary mode of transmission for respiratory infections like influenza, common cold, tuberculosis, and COVID-19, not typhoid fever.
- C) Direct skin contact with infected persons: While some infections like impetigo or scabies can spread through direct skin contact, typhoid fever is not typically transmitted this way.
- D) Bite of female Anopheles mosquito: This is the primary mode of transmission for malaria. Mosquitoes are vectors for various diseases, but not for typhoid fever.
16.
The diagnostic test used to confirm typhoid fever is:
Approach
The question asks to identify the diagnostic test specifically used to confirm typhoid fever. We need to evaluate each given option against its known medical application.
Step-by-step
- Understand Typhoid Fever: Typhoid fever is a bacterial infection caused by Salmonella Typhi. Diagnosis often involves detecting the bacteria itself or the body's immune response (antibodies) to it.
- Evaluate Option A (ELISA test): ELISA (Enzyme-Linked Immunosorbent Assay) is a general test used to detect antibodies or antigens in various diseases, including HIV, hepatitis, and Lyme disease. While it can be adapted for typhoid, it's not the primary or most specific test commonly associated with its confirmation in many regions.
- Evaluate Option B (Dick test): The Dick test is an outdated skin test used to determine susceptibility to scarlet fever, not typhoid fever.
- Evaluate Option C (Widal test): The Widal test is a serological test that detects the presence of antibodies (agglutinins) against the H (flagellar) and O (somatic) antigens of Salmonella Typhi in a patient's serum. It is widely used for the diagnosis of typhoid fever, especially in endemic areas.
- Evaluate Option D (Mantoux test): The Mantoux test (also known as the PPD test) is a skin test used to screen for tuberculosis (TB) infection, not typhoid fever.
- Conclusion: Based on the evaluation, the Widal test is the specific diagnostic test commonly used to confirm typhoid fever among the given options.
Correct Option: C) Widal test is a serological test used to detect antibodies against the Salmonella Typhi bacteria, which causes typhoid fever. It measures the agglutination of bacterial antigens by antibodies present in the patient's serum.
Incorrect Options
- A) ELISA test — ELISA (Enzyme-Linked Immunosorbent Assay) is a versatile immunoassay used for detecting antibodies or antigens for a wide range of diseases (e.g., HIV, hepatitis). While an ELISA can be developed for typhoid, it is not the universally recognized or most common diagnostic test specifically for typhoid fever as the Widal test is.
- B) Dick test — The Dick test is an old diagnostic test used to determine susceptibility to scarlet fever, a bacterial infection caused by Streptococcus pyogenes. It has no relevance to typhoid fever.
- D) Mantoux test — The Mantoux test, also known as the PPD (Purified Protein Derivative) test, is a skin test used to screen for tuberculosis (TB) infection. It involves injecting a small amount of tuberculin into the skin and checking for a reaction, indicating exposure to TB bacteria. It is not used for typhoid fever.
17.
The vaccine available for prevention of typhoid is:
Approach
The question asks to identify the vaccine used for the prevention of typhoid. This requires knowledge of common vaccines and the diseases they target.
Step-by-step
- Recall the names of common vaccines and the diseases they prevent.
- Evaluate each given option against the target disease (typhoid).
Correct Option: D) TAB vaccine
The TAB vaccine is specifically designed to prevent typhoid fever. The acronym TAB stands for Typhoid, Paratyphoid A, and Paratyphoid B, indicating its effectiveness against these related bacterial infections caused by Salmonella Typhi and Salmonella Paratyphi.
Incorrect Options
- A) OPV vaccine — OPV stands for Oral Polio Vaccine. It is used to prevent poliomyelitis, a viral disease that can cause paralysis. It is not used for typhoid.
- B) BCG vaccine — BCG stands for Bacillus Calmette-Guérin vaccine. It is primarily used for the prevention of tuberculosis (TB), a bacterial infection. It is not used for typhoid.
- C) DPT vaccine — DPT stands for Diphtheria, Pertussis (whooping cough), and Tetanus vaccine. It is a combination vaccine that protects against these three bacterial diseases. It is not used for typhoid.
18.
Cholera is caused by which pathogen?
ANSWER :
A. Vibrio cholerae
Approach
The question asks to identify the pathogen responsible for causing cholera. This requires knowledge of common infectious diseases and their causative agents.
Step-by-step
- Recall the common pathogens associated with various gastrointestinal diseases.
- Cholera is a severe diarrheal disease. Its characteristic symptoms are caused by a toxin produced by a specific bacterium.
- Identify which of the given options is the known causative agent of cholera.
Correct Option: A) Vibrio cholerae
Cholera is an acute diarrheal infection caused by ingestion of food or water contaminated with the bacterium Vibrio cholerae. This bacterium produces a toxin that leads to severe watery diarrhea, dehydration, and potentially death if not treated promptly.
Incorrect Options
- B) Rotavirus — Rotavirus is a common cause of severe diarrhea and vomiting in infants and young children worldwide, but it does not cause cholera. It is a virus, not a bacterium.
- C) Salmonella typhi — Salmonella typhi is the bacterium responsible for causing typhoid fever, a systemic illness characterized by high fever, fatigue, abdominal pain, and sometimes a rash. It is distinct from cholera.
- D) Entamoeba histolytica — Entamoeba histolytica is a parasitic amoeba that causes amoebiasis, which can manifest as amoebic dysentery (severe diarrhea with blood and mucus) or liver abscesses. It is not the cause of cholera.
