Infectious Diseases — MCQs

A person has presented with history of dog-bite on the uncovered surface of his right leg. There is a minor abrasion without bleeding. Consider the following statements about management : 1. The bite should be taken as a category I contact with suspect animal 2. The bite requires local treatment of the wound 3. The person requires immediate vaccination 4. The person requires immediate administration of rabies immunoglobulin Which of the above statements are correct ?

Infectious Diseases Indian Medical PG Practice Questions and MCQs

Question 211: To control Mansonia mosquitoes, the most effective method is:

A. Avoidance of water collections
B. Larvicidal insecticides
C. Removal of water plants (Correct Answer)
D. Oiling of water

Explanation: ***Correct: Removal of water plants*** - **Mansonia** mosquitoes have a unique biological adaptation where their **larvae and pupae attach to the roots and stems of aquatic plants** (like *Pistia*, *Eichhornia*, water lettuce) to obtain oxygen through a specialized respiratory siphon - **Removal of aquatic vegetation** is the **most effective control method** because it eliminates the attachment sites essential for larval and pupal respiration - Without host plants, the larvae and pupae cannot obtain oxygen and die, making this the **gold standard** for Mansonia control - This method provides long-term control by eliminating the breeding habitat *Incorrect: Larvicidal insecticides* - While larvicidal insecticides are effective for many mosquito species, they are **less effective for Mansonia** mosquitoes - Since Mansonia larvae remain submerged and attached to plant roots (not coming to the surface for air), conventional larvicides have difficulty reaching them - The larvae's unique oxygen-obtaining mechanism makes them relatively resistant to surface-applied larvicides *Incorrect: Avoidance of water collections* - **Mansonia** mosquitoes breed in large, permanent water bodies with extensive aquatic vegetation (ponds, marshes, swamps) - These are natural habitats that cannot be easily eliminated - Unlike container-breeding mosquitoes (e.g., *Aedes*), avoidance of water collections is impractical and ineffective for Mansonia control *Incorrect: Oiling of water* - **Oiling the water surface** creates a film that prevents mosquito larvae from accessing atmospheric oxygen at the surface - This method works for species like **Anopheles** and **Culex** whose larvae breathe from the water surface - It is **completely ineffective against Mansonia** because their larvae obtain oxygen directly from **aquatic plant roots beneath the surface**, not from atmospheric air

Question 212: Suraksha Clinics are conducted under the aegis of which National Health Programme?

A. Iodine Deficiency Disorders Programme
B. Reproductive and Child Health Programme (Correct Answer)
C. National AIDS Control Programme
D. Revised National Tuberculosis Control programme

Explanation: ***Reproductive and Child Health Programme*** - **Suraksha Clinics** (also known as Surakshit Matritva Suraksha or SMS Clinics) are established under the **Reproductive and Child Health (RCH) Programme** to provide comprehensive **maternal and child health services**. - These clinics offer services including **antenatal care (ANC), postnatal care (PNC), institutional deliveries, family planning**, and management of complications during pregnancy and childbirth. - They are part of India's efforts to ensure **safe motherhood** and reduce maternal and infant mortality rates. *National AIDS Control Programme* - This program focuses on **HIV/AIDS prevention, care, and treatment** through services like counseling, testing (ICTC), and antiretroviral therapy (ART centers). - While it operates various specialized centers for HIV care, **Suraksha Clinics are not part of NACP** but are specifically for maternal and child health. *Iodine Deficiency Disorders Programme* - This program aims to prevent **iodine deficiency** through universal salt iodization and monitoring of IDD prevalence. - It does not involve clinic-based maternal health services like Suraksha Clinics. *Revised National Tuberculosis Control Programme* - This program (now National TB Elimination Programme) is dedicated to **tuberculosis diagnosis, treatment, and control** through DOTS and other strategies. - It operates designated microscopy centers (DMCs) and treatment facilities, not Suraksha Clinics for maternal care.

Question 213: Consider the following diseases: 1. Yellow fever 2. Q fever 3. Chikungunya fever 4. Relapsing fever 5. Japanese encephalitis 6. Sleeping sickness Which of the above are transmitted by mosquitoes?

A. 4, 5 and 6
B. 1, 2, 3, and 6
C. 1, 3 and 5 (Correct Answer)
D. 2, 3 and 5

Explanation: ***1, 3 and 5*** - **Yellow fever** (1), **Chikungunya fever** (3), and **Japanese encephalitis** (5) are all **mosquito-borne viral diseases**. - These diseases are transmitted to humans through the bite of infected mosquitoes, primarily species like *Aedes* and *Culex*. *4, 5 and 6* - **Relapsing fever** (4) is transmitted by **ticks or lice**, not mosquitoes. - **Sleeping sickness** (6) is transmitted by the **tsetse fly**, not mosquitoes. *1, 2, 3, and 6* - **Q fever** (2) is caused by the bacterium *Coxiella burnetii* and is typically transmitted through **aerosols from infected animals**, not mosquitoes. - As mentioned, **Sleeping sickness** (6) is transmitted by the **tsetse fly**. *2, 3 and 5* - **Q fever** (2) is transmitted via **aerosols from infected animals**, not mosquitoes. - While Chikungunya fever (3) and Japanese encephalitis (5) are mosquito-borne, the inclusion of Q fever makes this option incorrect.

Question 214: Which states are qualified as high prevalence states in the context of HIV/AIDS?

A. When prevalence in high risk groups is less than 5%, and less than 1% in antenatal women
B. When prevalence in high risk groups is more than 5%, and 1% or more in antenatal women (Correct Answer)
C. When prevalence in high risk groups is less than 5%, and more than 1% in antenatal women
D. When prevalence in high risk groups is more than 5%, and less than 1% in antenatal women

Explanation: ***When prevalence in high risk groups is more than 5%, and 1% or more in antenatal women*** - A state is considered a **high prevalence state** for HIV/AIDS when the prevalence among **high-risk groups** (e.g., sex workers, injecting drug users, men who have sex with men) is **greater than 5%**. - Additionally, for a state to be classified as high prevalence, the prevalence among **antenatal women** (reflecting the general population) must be **1% or higher**. - According to **NACO guidelines**, meeting either or both of these criteria qualifies a state as high prevalence for targeted interventions. *When prevalence in high risk groups is less than 5%, and more than 1% in antenatal women* - This option is incorrect because while a prevalence of more than 1% in antenatal women suggests a significant issue, a prevalence of **less than 5%** in high-risk groups combined with the ANC criterion would not fully meet the high prevalence classification. - High prevalence in key affected populations (>5%) is a critical component of the classification criteria. *When prevalence in high risk groups is more than 5%, and less than 1% in antenatal women* - This option is incorrect because although a prevalence of more than 5% in high-risk groups is met, a prevalence of **less than 1%** in antenatal women indicates lower overall spread in the general population. - For high prevalence classification, the state must meet the threshold of either **>1% in ANC** OR **>5% in high-risk groups** (or both). *When prevalence in high risk groups is less than 5%, and less than 1% in antenatal women* - This option is incorrect as it represents a **low prevalence state** scenario where both indicators are below the threshold values. - States meeting these criteria would require different intervention strategies compared to high prevalence states.

Question 215: A 20 year old male is diagnosed as a case of dengue fever at a Primary Health Centre. What are the suitable measures to be taken for the prevention and control of dengue in that area?

A. Case management for DF and DHF, isolation and individual protection from mosquitoes and environmental measures for elimination of breeding places (Correct Answer)
B. Case management for DF and DHF and vaccination
C. Case management for DF and DHF, isolation and individual protection from mosquitoes and vaccination
D. Case management for DF and DHF, isolation and individual protection from mosquitoes

Explanation: **Correct Option: Case management for DF and DHF, isolation and individual protection from mosquitoes and environmental measures for elimination of breeding places** - **Integrated vector management** is the cornerstone of dengue control, combining case management, personal protection measures, and environmental sanitation to eliminate breeding sites - The term "isolation" here refers to **protecting dengue patients from mosquito bites during the viremic period** (first 5-7 days) to prevent mosquitoes from acquiring the virus and spreading it to others - This comprehensive approach addresses **all three pillars**: treating patients appropriately, preventing vector-human contact, and eliminating *Aedes* mosquito breeding habitats (stagnant water containers) - Environmental measures include source reduction, larviciding, and community mobilization for container management *Incorrect: Case management for DF and DHF and vaccination* - While case management is essential, dengue vaccines (Dengvaxia, TAK-003) have **limited efficacy and restricted indications** - Vaccination is **not recommended as a primary prevention strategy** in most endemic areas and requires prior dengue seropositivity screening - This option critically **omits vector control measures**, which are the mainstay of dengue prevention *Incorrect: Case management for DF and DHF, isolation and individual protection from mosquitoes and vaccination* - This option includes several appropriate measures but incorrectly emphasizes **vaccination as a core strategy** - Dengue control programs rely primarily on **vector management, not immunization** - Missing the critical component of **environmental breeding site elimination** *Incorrect: Case management for DF and DHF, isolation and individual protection from mosquitoes* - This option is incomplete as it **lacks environmental measures for eliminating mosquito breeding places** - Without addressing breeding sites (*Aedes aegypti* breeds in clean stagnant water), the mosquito population cannot be controlled - Environmental sanitation and source reduction are **fundamental to sustainable dengue control** and cannot be omitted

Question 216: Consider the following diseases: 1. Measles 2. Polio 3. Staphylococcal food poisoning 4. Typhoid Which of the above are the correct examples for incubation period of 10-14 days?

A. 1 and 4 (Correct Answer)
B. 2 and 4
C. 3 and 4
D. 1 and 3

Explanation: ***1 and 4*** - **Measles** has a typical incubation period of **10 to 14 days** from exposure to the onset of fever, fitting perfectly within the specified range. - **Typhoid fever** (caused by *Salmonella Typhi*) has an incubation period ranging from **7 to 21 days**, with **10-14 days being the average**, making it a correct example. *2 and 4* - **Polio** has an incubation period of **3 to 35 days** (commonly 6 to 20 days), which is too broad and variable to be classified specifically as a 10-14 day incubation disease. - Typhoid does fit the 10-14 day range, but Polio does not specifically match this criterion. *3 and 4* - **Staphylococcal food poisoning** has a very short incubation period of **30 minutes to 6 hours** due to preformed toxins, making it completely outside the 10-14 day range. - While Typhoid fits, Staphylococcal food poisoning clearly does not. *1 and 3* - While **Measles** correctly has a 10-14 day incubation period, **Staphylococcal food poisoning** has only **30 minutes to 6 hours**, making this combination incorrect.

Question 217: With reference to meningococcal meningitis, which one of the following statements is not correct?

A. Fatality in untreated cases is 60%
B. Disease spreads mainly by droplet infection
C. Treatment of cases has no significant effect in epidemiological pattern of disease (Correct Answer)
D. Mass chemoprophylaxis causes immediate drop in incidence rate of cases

Explanation: ***Treatment of cases has no significant effect in epidemiological pattern of disease*** - This statement is **NOT correct** because effective treatment of meningococcal meningitis cases **does reduce the duration of infectivity**, thereby limiting further spread and influencing the epidemiological pattern. - Treatment shortens the **carrier state** and reduces transmission to close contacts, having a significant **public health impact** beyond individual patient benefit. - Prompt antibiotic therapy (penicillin, ceftriaxone, or chloramphenicol) reduces infectivity within **24 hours**. *Fatality in untreated cases is 60%* - This statement is **correct**. Untreated meningococcal meningitis has a high fatality rate of **50-80%**, making 60% a reasonable and accurate estimate. - This underscores the critical importance of early diagnosis and prompt treatment. *Disease spreads mainly by droplet infection* - This statement is **correct**. **_Neisseria meningitidis_** is transmitted through **respiratory droplets** from nasopharyngeal secretions of carriers or cases. - Spread occurs through close contact in crowded settings such as hostels, military barracks, and schools. *Mass chemoprophylaxis causes immediate drop in incidence rate of cases* - This statement is **correct**. Mass chemoprophylaxis with **rifampicin, ciprofloxacin, or ceftriaxone** to close contacts effectively **eliminates the carrier state** and prevents secondary cases. - This leads to an **immediate reduction in disease incidence** during outbreaks.

Question 218: Rheumatic Heart Disease can be prevented by:

A. Treatment of respiratory infections in children (Correct Answer)
B. Screening of school going children
C. All of these
D. Vaccination against Streptococcus

Explanation: ***Treatment of respiratory infections in children (Correct Answer)*** - **Prompt and adequate treatment** of Group A Streptococcal pharyngitis (strep throat) with antibiotics (typically Penicillin) is the **primary prevention method** for acute rheumatic fever (ARF) and rheumatic heart disease (RHD). - This prevents the immune-mediated inflammatory response that leads to damage of heart valves, which is the hallmark of RHD. - **Primary prevention** involves treating the initial streptococcal infection within 9 days of onset to prevent ARF development. *Screening of school going children* - Screening asymptomatic school-going children is **not a primary prevention strategy** as it doesn't prevent the initial infection or immune response. - While screening can help identify **existing cases of RHD** for secondary prevention (preventing disease progression and recurrence), it doesn't prevent the initial development of the disease. - Secondary prevention with benzathine penicillin prophylaxis is used after RHD is detected. *All of these* - This option is incorrect because **only one of the listed activities** represents true primary prevention of RHD. - While a comprehensive RHD control program may include multiple strategies (treatment, screening, health education), not all the options listed are valid prevention methods. *Vaccination against Streptococcus* - A **highly effective vaccine against all relevant strains of Group A Streptococcus** is **not currently available** for general use. - Research into streptococcal vaccines is ongoing, but challenges include the large number of M-protein serotypes (>200) and concerns about autoimmunity. - Such a vaccine would be a major breakthrough in preventing ARF and RHD in the future.

Question 219: Asymptomatic carriers of pathogenic organisms are called:

A. Incubatory carriers
B. Healthy carrier (Correct Answer)
C. Pseudo carriers
D. Convalescent carriers

Explanation: ***Healthy carrier*** - A **healthy carrier** harbors a **pathogenic organism** without showing any symptoms of the disease itself. - These individuals can **transmit the infection** to others, making them important in the spread of disease. *Incubatory carriers* - **Incubatory carriers** are individuals who are in the **incubation period** of a disease. - They can transmit the pathogen **before symptomatic onset** but will eventually develop symptoms. *Pseudo carriers* - This term is **not standard terminology** in epidemiology to describe asymptomatic carriers. - It might refer to individuals who carry a non-pathogenic organism or who test positive falsely. *Convalescent carriers* - **Convalescent carriers** are individuals who have **recovered from a disease** but continue to shed the pathogen. - They have already experienced the symptoms of the illness and are in the recovery phase.

Question 220: A person has presented with history of dog-bite on the uncovered surface of his right leg. There is a minor abrasion without bleeding. Consider the following statements about management : 1. The bite should be taken as a category I contact with suspect animal 2. The bite requires local treatment of the wound 3. The person requires immediate vaccination 4. The person requires immediate administration of rabies immunoglobulin Which of the above statements are correct ?

A. 2 and 3 only (Correct Answer)
B. 1 and 2
C. 2, 3 and 4
D. 3 and 4 only

Explanation: ***2 and 3 only*** - A minor abrasion without bleeding falls under **Category II exposure** per WHO guidelines, requiring **local wound treatment** and **immediate vaccination**. - **Category II exposures** are defined as nibbling of uncovered skin, minor abrasions without bleeding, or scratches without bleeding. *1 and 2* - The bite described (minor abrasion without bleeding) is classified as **Category II exposure** by WHO, not Category I. - **Category I contact** involves touching or feeding an animal, or licks on intact skin, requiring **no post-exposure prophylaxis** as there is no breach of skin integrity. *2, 3 and 4* - While local wound treatment and vaccination are correct for Category II exposure, **rabies immunoglobulin (RIG)** is not indicated for Category II. - RIG is reserved for **Category III exposures**, which involve single or multiple transdermal bites or scratches, contamination of mucous membranes with saliva, or licks on broken skin. *3 and 4 only* - Immediate vaccination is correct, but **rabies immunoglobulin** is not necessary for a minor abrasion without bleeding (Category II exposure). - Administration of RIG is only indicated after **Category III exposures** due to the higher risk of rabies transmission.

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