Q80. Which pairing of a disease with its causative category is incorrect?
[UPSC CDS (I) 2026]
(A) Polio — viral
(B) Athlete’s foot — fungal
(C) Dengue — non-viral
(D) Whooping cough — bacterial
Answer: (C) Dengue — non-viral
Explanation: Dengue is caused by dengue virus, a flavivirus transmitted mainly by Aedes mosquitoes. Polio is also viral, athlete’s foot is a fungal infection, and whooping cough results from Bordetella pertussis bacteria. Thus the dengue classification is the erroneous pair.
Q79. Which laboratory method allows one-tube detection of dengue, chikungunya and Zika viruses?
[RRB Group D, 14 August 2026]
(A) Bacterial culture
(B) Multiplex real-time RT-PCR
(C) Blood glucose estimation
(D) Gram staining
Answer: (B) Multiplex real-time RT-PCR
Explanation: Multiplex real-time reverse-transcription PCR identifies genetic material from several RNA viruses in a single reaction. It offers rapid differential diagnosis where dengue, chikungunya and Zika share fever-like presentations. Gram staining and bacterial culture cannot directly identify these viral genomes.
Q78. How many assertions are correct:
Viruses cannot persist in sea water;
Cannot infect bacteria; and
Cannot alter host transcription?
[UPSC CSE Prelims 2025]
(A) Exactly one
(B) Exactly two
(C) All three
(D) None
Answer: (D) None
Explanation: All three assertions are false. Numerous viruses occur in marine environments; bacteriophages infect bacteria; and viruses can redirect gene expression in infected host cells. Viruses rely on living systems for replication, but they are ecologically widespread and biologically active.
Q77. Identify the incorrectly described vector–disease–pathogen combination.
[RPSC RAS Prelims 2025]
(A) Aedes – chikungunya – bacteria
(B) Culex – filariasis – parasitic worm
(C) Anopheles – malaria – protozoan
(D) Aedes – dengue – virus
Answer: (A) Aedes – chikungunya – bacteria
Explanation: Chikungunya is caused by an alphavirus rather than a bacterium, although Aedes mosquitoes are important vectors. Filariasis involves parasitic nematodes, malaria involves Plasmodium protozoa, and dengue is viral. The key is distinguishing a vector from the actual pathogen.
Q76. QDENGA, a tetravalent vaccine, is intended to prevent which mosquito-borne disease?
[RRB NTPC (UG), 4 September 2025]
(A) Dengue
(B) Malaria
(C) Chikungunya
(D) Japanese encephalitis
Answer: (A) Dengue
Explanation: QDENGA (TAK-003) targets dengue, which has four major virus serotypes. A tetravalent formulation aims to generate protection across these types. Malaria is protozoan, whereas chikungunya and Japanese encephalitis are caused by different viruses requiring different prevention strategies.
Q75. India observes National Vaccination Day on 16 March in connection with which vaccine campaign?
[RRB Group D, 16 December 2025]
(A) Influenza
(B) Polio
(C) Yellow fever
(D) Rabies
Answer: (B) Polio
Explanation: India marks 16 March as National Vaccination Day to commemorate the first oral polio vaccine administration under the 1995 campaign. The programme highlights childhood immunisation and efforts to interrupt poliovirus transmission before it can produce irreversible paralysis.
Q74. The National Polio Surveillance Network in India was developed with support from which organisation?
[RRB Group D, 19 December 2025]
(A) UNEP
(B) World Bank
(C) World Health Organization
(D) UNDP
Answer: (C) World Health Organization
Explanation: The World Health Organization collaborated with India on the National Polio Surveillance Network. Surveillance for acute flaccid paralysis and virological testing is essential because poliovirus can circulate silently even when relatively few infected people develop paralytic disease.
Q73. Which vaccine developed by Jonas Salk uses inactivated poliovirus?
[SSC CGL Tier-I, 9 September 2024]
(A) Salk vaccine
(B) Imvanex
(C) HDCV rabies vaccine
(D) TAB vaccine
Answer: (A) Salk vaccine
Explanation: Jonas Salk developed the inactivated poliovirus vaccine, administered by injection. It differs from the oral, live-attenuated vaccine associated with Albert Sabin. Both strategies have been central to controlling poliomyelitis, but their formulations and routes of administration differ.
Q72. Which virus most commonly causes the ordinary common cold?
[SSC MTS, 4 November 2024]
(A) Hepatitis A virus
(B) Influenza A virus
(C) Rhinovirus
(D) Rabies virus
Answer: (C) Rhinovirus
Explanation: Rhinoviruses account for many common colds, typically causing sneezing, nasal discharge and a sore throat. Other respiratory viruses can produce similar symptoms. Hepatitis A affects the liver, while rabies primarily attacks the nervous system after exposure to infected saliva.
Q71. COVID-19 is commonly discussed as a disease of which origin category?
[SSC MTS, 15 October 2024]
(A) Dietary deficiency
(B) Waterborne parasitosis
(C) Zoonotic origin
(D) Inherited metabolic disorder
Answer: (C) Zoonotic origin
Explanation: COVID-19 is caused by SARS-CoV-2, a coronavirus with a likely animal evolutionary origin. Zoonosis refers to disease transmission involving animal reservoirs and people. Once established in humans, COVID-19 spreads mainly between people through infectious respiratory particles.