Water Pollution and Health — MCQs
Under the original International Health Regulations, the internationally quarantinable diseases were -
Which of the following diseases is primarily water-related?
A 17 year old adolescent, presented with fever since one week which is step-ladder in pattern. He also has loose stools which are "pea-soup" in consistency. Rose spots are seen on his body. He is most probably infected with:
An industrial worker presents with blue lines on gums and tremors. What is the most probable diagnosis?
What is the correct method for collecting water for bacteriological examination during a disease outbreak?
The dead body of a child was recovered from a river with froth around his mouth, which reappeared even after wiping it off. Which postmortem finding is not seen in this case?
Which of the following is most specific for arsenic poisoning ?
All are causes of wrist drop (condition shown in the image below) except:
Which of the following is the least toxic organophosphorus compound?
Depression of consciousness level in hypothermia starts when the core body temperature falls below which value?
Water Pollution and Health Indian Medical PG Practice Questions and MCQs
Question 1: Under the original International Health Regulations, the internationally quarantinable diseases were -
- A. Cholera
- B. All of the above (Correct Answer)
- C. Plague
- D. Yellow fever
Explanation: ***All of the above*** - **Cholera**, **plague**, and **yellow fever** were the three diseases designated as internationally quarantinable under the **original International Health Regulations (IHR)** before the 2005 revision. - These diseases were selected due to their potential for rapid international spread and serious public health impact, requiring coordinated global surveillance and response. - **Note:** The IHR (2005), which came into force in 2007, replaced this fixed list with a framework for assessing **Public Health Emergencies of International Concern (PHEIC)** using a decision algorithm. *Cholera* - **Cholera** is an acute diarrheal illness caused by *Vibrio cholerae* that can cause severe dehydration and death if untreated, with high potential for **epidemic spread**, particularly in areas with poor sanitation. - It was designated as quarantinable due to its rapid transmission via contaminated water and food. *Plague* - **Plague**, caused by the bacterium *Yersinia pestis*, has historically caused devastating pandemics and remains a concern due to its high fatality rate and potential for spread through **vector transmission** (fleas) or **person-to-person transmission via pneumonic plague**. - Its inclusion reflected its capacity to cause widespread morbidity and mortality. *Yellow fever* - **Yellow fever** is a viral hemorrhagic disease transmitted by *Aedes* mosquitoes, posing risk in tropical and subtropical regions of Africa and South America. - Its quarantinable status stemmed from its potential for rapid spread into non-endemic areas by infected travelers and the presence of **competent mosquito vectors globally**.
Question 2: Which of the following diseases is primarily water-related?
- A. Scabies
- B. Yellow fever
- C. Cholera (Correct Answer)
- D. Dysentery
Explanation: ***Cholera*** - Cholera is caused by the bacterium **Vibrio cholerae**, which is typically transmitted through the consumption of **contaminated water or food**. - This disease is a classic example of a **waterborne illness**, with outbreaks often linked to inadequate sanitation and unsafe drinking water. *Yellow fever* - Yellow fever is a **viral hemorrhagic disease** transmitted by infected **mosquitoes**, primarily Aedes aegypti. - While mosquitoes may breed in water, the disease itself is not directly transmitted through water consumption. *Scabies* - Scabies is a **skin infestation** caused by the mite **Sarcoptes scabiei**, which burrows into the outer layer of the skin. - Transmission occurs through **direct, prolonged skin-to-skin contact**, not through water. *Dysentery* - Dysentery is an **intestinal inflammation** causing bloody diarrhea, which can be caused by bacteria (e.g., Shigella) or amoebas (e.g., Entamoeba histolytica). - Although it can be transmitted through contaminated water or food, it is a broader term for a symptom, and **cholera is more exclusively and primarily focused on water-borne transmission mechanisms**.
Question 3: A 17 year old adolescent, presented with fever since one week which is step-ladder in pattern. He also has loose stools which are "pea-soup" in consistency. Rose spots are seen on his body. He is most probably infected with:
- A. Salmonella typhi (Correct Answer)
- B. Adenovirus
- C. Rotavirus
- D. Vibrio cholerae
Explanation: ***Salmonella typhi*** - The combination of **step-ladder fever**, **"pea-soup" diarrhea**, and **rose spots** is a classic presentation of **typhoid fever**, caused by *Salmonella typhi* [1]. - This bacterial infection predominantly affects the gastrointestinal tract and can lead to systemic symptoms [1]. *Adenovirus* - **Adenovirus** typically causes **respiratory tract infections**, **conjunctivitis**, or **gastroenteritis**, but not with the specific symptom profile of step-ladder fever or rose spots. - While it can cause diarrhea, it's usually not described as "pea-soup" and lacks the other systemic features. *Rotavirus* - **Rotavirus** is a common cause of **severe gastroenteritis** in infants and young children, characterized by **watery diarrhea** and vomiting. - It does not present with step-ladder fever or rose spots, which are pathognomonic for typhoid. *Vibrio cholerae* - **Vibrio cholerae** causes **cholera**, an acute diarrheal illness characterized by **profuse watery diarrhea** (often described as "rice-water stools") and rapid dehydration. - It does not typically cause step-ladder fever or skin manifestations like rose spots.
Question 4: An industrial worker presents with blue lines on gums and tremors. What is the most probable diagnosis?
- A. Mercury
- B. Lead (Correct Answer)
- C. Arsenic poisoning
- D. Carbon monoxide
Explanation: ***Lead*** - **Blue lines on the gums (Burton's lines)** are a classic symptom of chronic lead poisoning, caused by a reaction between circulating lead and sulfur ions released by oral bacteria [2]. - **Tremors** and other neurological symptoms like *wrist drop* or *foot drop* are common manifestations of lead's neurotoxic effects [1]. *Mercury* - While **tremors** are a prominent symptom of mercury poisoning, especially *finger tremors* and *erectile dysfunction*, **blue lines on the gums** are not characteristic [3]. - Mercury poisoning is often associated with **gingivitis**, **stomatitis**, and *Erythrism* (mad hatter disease), which involves psychological changes like irritability and shyness [3]. *Arsenic poisoning* - **Arsenic poisoning** can cause **neuropathy**, but **tremors** and **blue lines on the gums** are not typical features. - It classically presents with **rain drop skin pigmentation**, **hyperkeratosis**, and **Mees' lines** (transverse white bands on nails). *Carbon monoxide* - **Carbon monoxide poisoning** primarily affects the cardiovascular and central nervous systems, leading to symptoms like **headache**, **nausea**, and cherry-red skin coloration. - **Blue lines on the gums** and **tremors** are not associated with carbon monoxide toxicity.
Question 5: What is the correct method for collecting water for bacteriological examination during a disease outbreak?
- A. Collect water from already leaking taps
- B. Collect water from a tap after letting it flow for at least 1 minute to ensure freshness (Correct Answer)
- C. Collect from a gentle stream of water to avoid splashing
- D. Before collecting, let water flow for at least 1 minute
Explanation: ***Correct: Collect water from a tap after letting it flow for at least 1 minute to ensure freshness*** - This is the **standard protocol** for bacteriological water sampling as per WHO and APHA guidelines - Flushing for **at least 1 minute** removes stagnant water from pipes and tap fixtures that may contain biofilms or non-representative bacterial contamination - This ensures the sample represents the **actual water supply** rather than water sitting in pipes - The complete statement includes both the flushing step AND the collection, making it a **complete procedure** *Incorrect: Collect water from already leaking taps* - Leaking taps contain **stagnant water** with biofilm accumulation that is not representative of the main water supply - Continuous dripping allows **external contamination** from air and surrounding surfaces - Does not follow standard water sampling protocols *Incorrect: Collect from a gentle stream of water to avoid splashing* - While avoiding splashing is important to prevent external contamination, this option **omits the critical flushing step** - Without prior flushing, the sample may contain bacteria from **stagnant water in pipes** rather than the actual supply - Incomplete methodology *Incorrect: Before collecting, let water flow for at least 1 minute* - While this describes the flushing step correctly, it is **incomplete as a method** - It states "before collecting" but doesn't describe the actual collection process - The question asks for the "correct method" which should include the complete procedure, not just a preparatory step
Question 6: The dead body of a child was recovered from a river with froth around his mouth, which reappeared even after wiping it off. Which postmortem finding is not seen in this case?
- A. High concentration of arsenic from shaft of hair (Correct Answer)
- B. Voluminous and ballooned out lungs
- C. Cadaveric spasm with mud in closed fist
- D. Paltauf's hemorrhage in sub pleura
Explanation: ***High concentration of arsenic from the shaft of hair*** - The presence of arsenic in hair is indicative of chronic **arsenic poisoning**, which is unrelated to drowning. - The scenario describes a body recovered from a river with froth, suggesting **drowning**, not poisoning. *Voluminous and ballooned out lungs* - This is a classic postmortem finding in drowning due to the aspiration of water and air trapping, leading to **pulmonary emphysema acquosum**. - The lungs appear large and distended, often with impressions of the ribs on their surfaces. *Cadaveric spasm with mud in a closed fist* - **Cadaveric spasm** (instantaneous rigor) can occur in cases of violent death, intense physical exertion, or emotional stress just before death, often seen in drowning victims. - Finding foreign material like mud or weeds clutched tightly in the hand is a significant indicator that the victim was **alive and struggling** in the water during submersion. *Paltauf's hemorrhage in subpleura* - **Paltauf's hemorrhages** are small, pinpoint hemorrhages found under the pleural surface (subpleural) and are a characteristic sign of drowning. - They result from the rupture of capillaries due to the sudden increase in intrathoracic pressure during the struggle to breathe underwater.
Question 7: Which of the following is most specific for arsenic poisoning ?
- A. Garlic-like odor in breath and urine (Correct Answer)
- B. Blue line on gums
- C. Tremors
- D. Anemia
Explanation: ***Garlic-like odor in breath and urine*** - A **garlic-like odor** in the breath and urine is a classic and highly **specific sign** of **arsenic poisoning**. - This distinctive odor is due to the **methylation of arsenic** compounds in the body. *Blue line on gums* - A **blue line on the gums**, also known as a **Burton line**, is characteristic of **lead poisoning**, not arsenic. - It results from the deposition of **lead sulfide** in the gingival tissue. *Tremors* - **Tremors** can be a symptom of various toxic exposures and neurological conditions, making them a **non-specific finding** for arsenic poisoning alone. - While **chronic arsenic poisoning** can lead to neurological symptoms, tremors are not a primary distinguishing feature. *Anemia* - **Anemia** is a common and **non-specific sign** that can be caused by many conditions, including various toxic exposures. - While chronic arsenic exposure can lead to **bone marrow suppression** and anemia, it is not specific enough for diagnosis.
Question 8: All are causes of wrist drop (condition shown in the image below) except:
- A. Arsenic toxicity
- B. Lead poisoning
- C. Use of crutches
- D. Zinc poisoning (Correct Answer)
Explanation: ***Zinc poisoning*** - **Zinc poisoning** is not a characteristic cause of **wrist drop**, which is typically associated with **radial nerve palsy**. - While excessive zinc can cause copper deficiency and neurological issues, it does not directly lead to **radial nerve entrapment** or damage causing wrist drop. *Arsenic toxicity* - **Chronic arsenic poisoning** can lead to **peripheral neuropathy**, which may include motor weakness such as **wrist drop**. - The neurological damage is often dose-dependent and can affect various peripheral nerves. *Lead poisoning* - **Lead poisoning** is a well-known cause of **radial nerve palsy**, leading to **wrist drop**. - This is often seen in occupational exposures and can be quite specific to the **radial nerve**. *Use of crutches* - Prolonged or improper use of **crutches** can cause compression of the **radial nerve** in the axilla, leading to **crutch palsy**. - **Crutch palsy** manifests as weakness of the **forearm and hand extensors**, resulting in **wrist drop**.
Question 9: Which of the following is the least toxic organophosphorus compound?
- A. Parathion
- B. Malathion
- C. Fenitrothion
- D. Abate (Correct Answer)
Explanation: ***Abate (Temephos)*** - **Abate** is specifically designed for use in water as a mosquito larvicide and has a notably **lower mammalian toxicity** compared to other organophosphates. - Its chemical structure and metabolic breakdown in mammals make it less potent in inhibiting **acetylcholinesterase**. *Malathion* - While generally considered less toxic than some other organophosphates like parathion, **malathion** still poses significant toxicity, especially with **high or prolonged exposure**. - It is metabolically activated to **malaoxon**, a more potent acetylcholinesterase inhibitor. *Fenitrothion* - **Fenitrothion** is an organophosphate insecticide with moderate to high toxicity, similar to malathion, but often considered more toxic for some species. - It works by inhibiting **cholinesterase enzymes**, leading to a buildup of acetylcholine. *Parathion* - **Parathion** is one of the most highly toxic organophosphorus compounds, historically used as a powerful insecticide but now restricted or banned in many countries due to its severe toxicity. - It is readily absorbed and metabolically converted to **paraoxon**, a very potent cholinesterase inhibitor.
Question 10: Depression of consciousness level in hypothermia starts when the core body temperature falls below which value?
- A. 35°C
- B. 34°C
- C. 33°C
- D. 32°C (Correct Answer)
Explanation: **Explanation:** Hypothermia is defined as a core body temperature below **35°C (95°F)**. It is clinically categorized into mild, moderate, and severe stages based on the physiological response of the body. **Why 32°C is the Correct Answer:** The transition from mild to **moderate hypothermia** occurs at **32°C (89.6°F)**. This is a critical physiological threshold where the body’s compensatory mechanisms (like shivering) begin to fail. At this temperature, cerebral metabolism slows significantly, leading to a progressive **depression of the consciousness level**, characterized by stupor, confusion, and eventual coma. **Analysis of Incorrect Options:** * **35°C (Option A):** This is the threshold for **Mild Hypothermia**. At this stage, the patient is fully conscious but may exhibit shivering, tachycardia, and tachypnea as the body attempts to generate heat. * **34°C & 33°C (Options B & C):** These temperatures fall within the range of mild hypothermia. While the patient may experience dysarthria (slurred speech) or ataxia, the global depression of consciousness typically does not manifest until the temperature drops below the 32°C mark. **High-Yield Clinical Pearls for NEET-PG:** 1. **Paradoxical Undressing:** Seen in severe hypothermia; the victim feels hot due to sudden vasodilation and removes clothes before death. 2. **Hide-and-Die Syndrome (Terminal Burrowing):** An instinctual behavior where the victim crawls into small, enclosed spaces. 3. **Post-mortem Findings:** Look for **Wischnewski spots** (hemorrhagic gastric erosions) and bright pink/cherry-red discoloration of the skin (due to oxyhemoglobin shift). 4. **J-Wave (Osborn Wave):** A characteristic ECG finding (deflection at the R-ST junction) seen when the temperature drops below 32°C.
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