UPSC Prelims 2017 Q31: Science & Technology – Health & Diseases
Consider the following statements:
1. In tropical regions, Zika virus disease is transmitted by the same mosquito that transmits
dengue.
2. Sexual transmission of Zika virus disease is possible.
Which of the statements given above is/are correct?
- (a) 1 only
- (b) 2 only
- (c) Both 1 and 2
- (d) Neither 1 nor 2
Answer: (c) Both 1 and 2
Explanation
Zika virus disease
Zika is a flavivirus first found in a monkey in the Zika forest, Uganda (1947).
| Statement | Verdict | Fact |
|---|---|---|
| 1. In tropical regions, Zika is transmitted by the same mosquito that transmits dengue | Correct | Both are spread by Aedes aegypti, a day-biting mosquito |
| 2. Sexual transmission of Zika virus disease is possible | Correct | The virus stays in semen and can pass between sexual partners |
Routes of transmission:
| Route | Detail |
|---|---|
| Mosquito bite | Aedes aegypti mainly; also Aedes albopictus |
| Sexual contact | Confirmed by WHO |
| Mother to foetus | Can cause microcephaly (small head) in the baby |
| Blood transfusion | Possible |
WHO declared Zika a Public Health Emergency of International Concern in February 2016.
Answer: (c) Both 1 and 2.
Why each option is right or wrong
- (a) Incorrect. Statement 2 is also true: Zika can spread through sexual contact.
- (b) Incorrect. Statement 1 is also true: Aedes aegypti spreads both Zika and dengue.
- (c) CORRECT. Zika shares the Aedes mosquito with dengue and can also be sexually transmitted.
- (d) Incorrect. Both statements are true; neither the mosquito link nor the sexual route is wrong.
Key point
Zika: spread by Aedes aegypti (same as dengue, chikungunya, yellow fever); also sexual, mother-to-foetus and blood routes; causes microcephaly.
Remember
Zika = Aedes mosquito + sexual transmission + microcephaly.
Common mistakes
- Thinking Zika is spread by the Anopheles mosquito, which spreads malaria.
- Assuming a mosquito-borne disease cannot also spread from person to person.
- Forgetting the link between Zika in pregnancy and microcephaly in babies.
Exam tip
Aedes aegypti carries four diseases: dengue, chikungunya, yellow fever and Zika.
Sources
- World Health Organization — Zika virus: fact sheet
- National Centre for Vector Borne Diseases Control — Aedes-borne diseases