Horrock's apparatus is used to measure :
The order of priority of immunization strategy to prevent congenital rubella infection from first to last is :
Diethyltoluamide is an effective :
UPSC-CMS 2013 - Community Medicine UPSC-CMS Practice Questions and MCQs
Question 21: Horrock's apparatus is used to measure :
- A. Free and combined chlorine
- B. Chlorine demand
- C. Free chlorine (Correct Answer)
- D. Combined chlorine
Explanation: ***Free chlorine*** - Horrock's apparatus is a device specifically designed for the **estimation of residual free chlorine** in treated water. - It uses a tablet and a comparator system to visually match the color produced with a standard scale, indicating the free chlorine level. *Free and combined chlorine* - This apparatus is specifically designed for **free chlorine** and does not directly measure combined chlorine. - While total chlorine (free + combined) can be inferred through subsequent tests, the Horrock's apparatus itself isolates free chlorine. *Chlorine demand* - **Chlorine demand** refers to the amount of chlorine used up by impurities in water before a residual begins to form, and is not directly measured by Horrock's apparatus. - It is determined by knowing the added chlorine dose and the residual chlorine remaining after a contact period. *Combined chlorine* - **Combined chlorine** refers to chlorine that has reacted with ammonia or organic nitrogen compounds, forming chloramines, and is not the primary measurement of Horrock's apparatus. - Measuring combined chlorine typically involves different methods or calculations after determining free and total chlorine.
Question 22: The order of priority of immunization strategy to prevent congenital rubella infection from first to last is :
- A. Women of reproductive age group → children 1-14 years → Infants
- B. Infants → women of reproductive age group → children 1-14 years
- C. Women of reproductive age group → Infants → children 1-14 years
- D. Infants → children 1-14 years → women of reproductive age group (Correct Answer)
Explanation: ***Infants → children 1-14 years → women of reproductive age group*** - **Infants first**: Establishing **routine infant immunization** (MR/MMR vaccine) is the cornerstone of sustainable rubella control and prevention of congenital rubella syndrome (CRS). - **Children 1-14 years**: Conducting **catch-up campaigns** in this age group rapidly builds **herd immunity** and interrupts rubella virus circulation in the community. - **Women of reproductive age**: Supplementary vaccination of susceptible women provides additional protection but should only be implemented **after** establishing routine infant immunization to avoid the **"honeymoon period" paradox**. - This sequence follows **WHO-recommended rubella immunization strategy** for achieving CRS elimination while maintaining long-term sustainability. *Women of reproductive age group → children 1-14 years → Infants* - Prioritizing women first without establishing routine infant immunization is **not sustainable** and can paradoxically increase CRS risk in the long term. - This approach fails to interrupt viral transmission and leaves future generations vulnerable once selective vaccination campaigns end. *Infants → women of reproductive age group → children 1-14 years* - While starting with infants is correct, vaccinating women before the 1-14 year age group is **less efficient** for rapidly building herd immunity. - Children aged 1-14 years are the **primary drivers of rubella transmission** in communities and should be prioritized for catch-up campaigns. *Women of reproductive age group → Infants → children 1-14 years* - This sequence incorrectly places women first and delays vaccination of the 1-14 year age group, who are **critical for establishing herd immunity**. - Without addressing the major reservoir of infection (older children), pregnant women remain at risk from community transmission.
Question 23: Diethyltoluamide is an effective :
- A. Agent against propagation of Anopheles
- B. Space spray
- C. Repellent (Correct Answer)
- D. Larvicide
Explanation: ***Repellent*** - **Diethyltoluamide (DEET)** is a highly effective and widely used **insect repellent**. - It works by creating an olfactory barrier that deters mosquitoes and other biting insects. *Agent against propagation of Anopheles* - While DEET can prevent bites from **Anopheles mosquitoes**, it doesn't directly target their reproduction or population growth. - Measures against propagation typically involve **larvicides**, habitat modification, or insecticidal spraying. *Space spray* - **Space sprays** are designed to kill insects in an area, often using insecticides like pyrethroids, rather than repelling them from an individual. - DEET's mechanism is to deter insects from landing on skin or clothing, not to kill them in an open space. *Larvicide* - **Larvicides** are chemical or biological agents used to kill insect larvae, particularly mosquito larvae, in aquatic breeding sites. - DEET is applied to the skin or clothing to prevent adult insect bites and does not act on larvae.