Vector Control — MCQs
Most important strategy for control of malaria in an endemic area:
Which of the following is an example of a barrier method of contraception?
Which of the following diseases is not included in the National Vector Borne Disease Control Program?
Which of the following is NOT included in the National Vector Borne Disease Control Programme (NVBDCP)?
The Roll Back Malaria programme focused mainly on
Which of the following statements about DDT is false?
Which of the following viral diseases is least commonly reported in India?
Rickettsial organisms infect humans worldwide, although geographic locations may be limited for some species and possibly produce some challenges in medical diagnosis. All are obligate intracellular parasites, except C. burnetii, and transmitted by an insect vector. Typhus, spotted fever, and scrub typhus share which of the following manifestations of disease?
All are components of Jai Vigyan Mission Mode project on community control of RF/RHD in India EXCEPT:
To control Mansonia mosquitoes, the most effective method is:
Vector Control Indian Medical PG Practice Questions and MCQs
Question 1: Most important strategy for control of malaria in an endemic area:
- A. Vector control (Correct Answer)
- B. Chemoprophylaxis
- C. Early treatment of cases
- D. Elimination of plasmodium
Explanation: ***Vector control*** - **Vector control** strategies, such as **insecticide-treated bed nets (ITNs)** and **indoor residual spraying (IRS)**, are the most effective in reducing malaria transmission by targeting the Anopheles mosquito - By reducing the mosquito population and their biting rates, vector control significantly cuts down the number of infected bites, leading to a substantial decrease in malaria incidence - This is the **cornerstone of WHO's Global Malaria Programme** and has proven most cost-effective for endemic areas *Incorrect: Chemoprophylaxis* - Chemoprophylaxis involves taking antimalarial drugs to prevent infection, which is effective for individuals or travelers but not sustainable or scalable for mass control in endemic populations - Widespread use would be cost-prohibitive and could accelerate **antimalarial drug resistance** *Incorrect: Early treatment of cases* - Early treatment with effective antimalarials reduces disease severity and prevents onward transmission, which is crucial for managing the disease burden - However, it does not directly prevent new infections or interrupt the transmission cycle as effectively as vector control at a population level - This is a **secondary strategy** that complements but does not replace vector control *Incorrect: Elimination of plasmodium* - Elimination of Plasmodium refers to eradication of the parasite, which is the ultimate goal, but it is not a direct "strategy" in itself but rather the **outcome** of successful control measures - Complete eradication is ambitious and challenging; current efforts focus on breaking the transmission cycle through vector control and effective case management
Question 2: Which of the following is an example of a barrier method of contraception?
- A. Hormonal contraceptive
- B. IUD
- C. Condom (Correct Answer)
- D. Sterilization
Explanation: ***Condom*** - A **condom** acts as a physical barrier, preventing sperm from reaching the egg. - Both male and female condoms are examples of **barrier contraception**. *Hormonal contraceptive* - **Hormonal contraceptives** work by preventing ovulation, thickening cervical mucus, or altering the uterine lining, not by physically blocking sperm. - Examples include oral contraceptive pills, patches, and vaginal rings. *IUD* - An **intrauterine device (IUD)**, whether hormonal or copper, primarily prevents conception by creating an inhospitable environment for sperm or by preventing implantation. - It is a long-acting reversible contraceptive, not a barrier method. *Sterilization* - **Sterilization** (e.g., tubal ligation or vasectomy) is a permanent method of contraception that prevents the transport of eggs or sperm, respectively. - It does not involve a physical barrier to block sperm during intercourse.
Question 3: Which of the following diseases is not included in the National Vector Borne Disease Control Program?
- A. Tuberculosis (Correct Answer)
- B. Japanese encephalitis
- C. Malaria
- D. Dengue
Explanation: ***Tuberculosis*** - **Tuberculosis** is a bacterial infection primarily affecting the lungs and is not transmitted by a vector. - It is controlled under the **National TB Elimination Programme (NTEP)**, a separate national health program. *Japanese encephalitis* - **Japanese encephalitis** is a viral disease transmitted by mosquitoes, making it a vector-borne disease. - It is one of the diseases specifically targeted by the **National Vector Borne Disease Control Program (NVBDCP)**. *Malaria* - **Malaria** is a parasitic disease transmitted by Anopheles mosquitoes, clearly categorizing it as vector-borne. - It is a primary focus of the **NVBDCP** due to its significant public health impact. *Dengue* - **Dengue** is a viral disease transmitted by Aedes mosquitoes, hence a vector-borne disease. - **Dengue control and prevention** are key objectives of the **NVBDCP**.
Question 4: Which of the following is NOT included in the National Vector Borne Disease Control Programme (NVBDCP)?
- A. Malaria
- B. Tuberculosis (Correct Answer)
- C. Filarial
- D. Kala azar
Explanation: ***Tuberculosis*** - **Tuberculosis is a bacterial disease** spread via airborne droplets, primarily affecting the lungs, and is **not a vector-borne disease**. - It is managed under the **Revised National Tuberculosis Control Programme (RNTCP)** in India, distinct from vector-borne disease programs. *Malaria* - Malaria is a **mosquito-borne parasitic disease** caused by Plasmodium parasites, and it is a major focus of the **NVBDCP**. - The program aims to reduce morbidity and mortality due to malaria through various control strategies. *Filarial* - **Filariasis (lymphatic filariasis)** is a mosquito-borne parasitic disease caused by filarial worms, and its elimination is a key objective of the **NVBDCP**. - The program focuses on mass drug administration and vector control to prevent its spread. *Kala Azar* - **Kala Azar (visceral leishmaniasis)** is a vector-borne disease transmitted by the bite of infected **sandflies**, making it a target disease under the **NVBDCP**. - The program implements surveillance, case management, and vector control measures to eliminate Kala Azar.
Question 5: The Roll Back Malaria programme focused mainly on
- A. IEC campaigns for community awareness
- B. Insecticide treated bed nets (Correct Answer)
- C. Development of larvivorous fishes for eradication of larvae.
- D. Presumptive treatment of malaria case
Explanation: ***Insecticide treated bed nets*** - The **Roll Back Malaria (RBM)** program, launched in 1998, focused significantly on key interventions including the promotion and distribution of **insecticide-treated nets (ITNs)**. - ITNs are highly effective in **preventing mosquito bites**, thus reducing malaria transmission, especially in vulnerable populations. *IEC campaigns for community awareness* - While **Information, Education, and Communication (IEC)** campaigns are crucial for health programs, they were a supportive component rather than the primary focus of RBM's core intervention strategy. - RBM emphasized **tangible interventions** with direct impact on disease transmission. *Development of larvivorous fishes for eradication of larvae* - The use of **larvivorous fish** is a form of biological control, which is typically part of **integrated vector management** but not the central pillar of RBM's strategy. - RBM prioritized interventions with **broad, immediate impact** across larger populations. *Presumptive treatment of malaria case* - **Presumptive treatment** (treating based on symptoms without laboratory confirmation) was an important aspect of early malaria control but not the main strategic thrust of the RBM initiative. - RBM's primary focus was on **prevention and rapid diagnosis/treatment** using effective antimalarials, and vector control strategies.
Question 6: Which of the following statements about DDT is false?
- A. It is contact poison
- B. Residual effect lasts for 18 months (Correct Answer)
- C. Is lipophilic in nature
- D. Belongs to organochlorine group
Explanation: ***Residual effect lasts for 18 months*** - **DDT's residual insecticidal effect** typically lasts only **3-12 months** when applied as an indoor residual spray, making 18 months definitively **FALSE**. - While DDT persists in the environment for years due to bioaccumulation, its **active insecticidal residual effect** on treated surfaces is much shorter than 18 months. - This is the **FALSE statement** among the options. *It is contact poison* - **TRUE**: DDT acts as a **contact poison**, being absorbed through the insect's **cuticle** upon direct contact. - It disrupts **sodium channels** in the nervous system, causing neurological overstimulation, tremors, and paralysis. *Is lipophilic in nature* - **TRUE**: DDT is highly **lipophilic** (fat-soluble), which explains its bioaccumulation in fatty tissues. - This lipophilicity leads to **biomagnification** through the food chain, causing environmental and health concerns. *Belongs to organochlorine group* - **TRUE**: DDT (Dichlorodiphenyltrichloroethane) is a classic example of an **organochlorine insecticide**. - Other organochlorines include lindane, aldrin, and dieldrin.
Question 7: Which of the following viral diseases is least commonly reported in India?
- A. Japanese B encephalitis
- B. Lassa fever (Correct Answer)
- C. KFD
- D. Dengue
Explanation: ***Lassa fever*** - **Lassa fever** is endemic to West Africa, with the **multimammate rat** being its primary reservoir. - Cases of Lassa fever are **extremely rare** in India, primarily limited to travel-related instances due to the geographical distribution of the disease and its vector. *Japanese B encephalitis* - **Japanese B encephalitis (JBE)** is a significant public health concern in India, particularly in endemic regions. - It is a mosquito-borne viral disease, and **vaccination programs** are ongoing to control its spread. *KFD* - **Kyasanur Forest Disease (KFD)** is an endemic viral hemorrhagic fever primarily found in the **Karnataka state of India**. - It is transmitted by **ticks**, making it a regionally significant but recognized viral disease within India. *Dengue* - **Dengue** is one of the most commonly reported and widespread viral diseases in India. - It is a **mosquito-borne** illness with frequent outbreaks occurring across various parts of the country.
Question 8: Rickettsial organisms infect humans worldwide, although geographic locations may be limited for some species and possibly produce some challenges in medical diagnosis. All are obligate intracellular parasites, except C. burnetii, and transmitted by an insect vector. Typhus, spotted fever, and scrub typhus share which of the following manifestations of disease?
- A. Arthritis
- B. Common vector
- C. Fever and rash (Correct Answer)
- D. Short incubation period (<48 hours)
Explanation: ***Fever and rash*** - **Fever** is a universal response to infection, and **rash** is a common dermatological manifestation due to **vascular damage** caused by rickettsial organisms. [1] - The combination of **fever** and **rash** is a hallmark sign in clinical presentations of **typhus**, **spotted fever group rickettsioses**, and **scrub typhus**. [1] *Arthritis* - While arthritis can occur in some infectious diseases, it is **not a characteristic or common manifestation** across all rickettsial diseases mentioned. - The primary targets for rickettsial organisms are **endothelial cells**, leading to vasculitis, rather than direct joint involvement. *Common vector* - The rickettsial diseases mentioned are transmitted by **different vectors**: typhus by **lice or fleas**, spotted fever by **ticks**, and scrub typhus by **chiggers**. [1] - Therefore, they do **not share a common insect vector**. *Short incubation period (<48 hours)* - Rickettsial diseases typically have an incubation period ranging from **5 to 14 days**, which is considerably longer than 48 hours. [1] - A very short incubation period (<48 hours) is more typical of **bacterial food poisonings** or **viral infections** like influenza.
Question 9: All are components of Jai Vigyan Mission Mode project on community control of RF/RHD in India EXCEPT:
- A. Vaccine development for streptococcal infection (Correct Answer)
- B. To study the epidemiology of streptococcal sore throats
- C. Antibiotic treatment of streptococcal sore throats
- D. To establish registries for RF and RHD
Explanation: ***Vaccine development for streptococcal infection*** - While **vaccine development** for Group A Streptococcus (GAS) is a long-term goal in controlling Rheumatic Fever (RF) and Rheumatic Heart Disease (RHD), it was **not an immediate component** of the Jai Vigyan Mission Mode project. - The mission focused on existing, actionable strategies for community control, rather than basic research and development of new interventions. *To study the epidemiology of streptococcal sore throats* - Understanding the **epidemiology of streptococcal sore throats** (the precursor to RF) is crucial for identifying high-risk populations and tailoring intervention strategies. - This component helps in mapping the incidence and prevalence of infections required to implement effective control strategies. *Antibiotic treatment of streptococcal sore throats* - **Prompt antibiotic treatment** of streptococcal sore throats is a cornerstone of primary prevention for RF, preventing the immune response that leads to the disease. - This is a direct, immediate intervention aimed at breaking the chain of infection and disease progression. *To establish registries for RF and RHD* - Establishing **registries for RF and RHD** is essential for monitoring disease burden, tracking outcomes, and evaluating the effectiveness of control programs. - Registries provide valuable data for public health planning and resource allocation.
Question 10: 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
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