Viral Diseases Archives

1. What is the causative agent of West Nile fever ?

What is the causative agent of West Nile fever ?

Bacteria

Virus

Protozoa

Fungus

This question was previously asked in

UPSC Combined Section Officer – 2024

Download PDF Attempt Online

West Nile fever is a viral infection transmitted primarily by mosquitoes. The causative agent is the West Nile virus (WNV).

– West Nile fever is caused by a virus.
– The virus is transmitted by mosquitoes.

West Nile virus is a single-stranded RNA virus that belongs to the genus Flavivirus, family Flaviviridae. It is commonly found in Africa, Europe, the Middle East, West Asia, and North America. Most people infected with WNV have no symptoms, but some develop fever, headache, body aches, joint pains, vomiting, diarrhea, or rash. A small percentage develop severe illness affecting the central nervous system.

2. The term ‘ACE2’ is talked about in the context of

The term ‘ACE2’ is talked about in the context of

genes introduced in the genetically modified plants

development of India's own satellite navigation system

radio collars for wildlife tracking

spread of viral diseases

This question was previously asked in

UPSC IAS – 2021

Download PDF Attempt Online

The term ‘ACE2’ stands for Angiotensin-converting enzyme 2. This enzyme is a protein found on the surface of many cells, particularly in the lungs, heart, kidneys, and intestines. It became widely known because it serves as the primary receptor that the SARS-CoV-2 virus (which causes COVID-19) uses to enter human cells. Therefore, ACE2 is talked about extensively in the context of the spread of viral diseases, specifically COVID-19.

– ACE2 is a protein enzyme found on cell surfaces.
– It acts as a receptor for coronaviruses, including SARS-CoV-2.
– The binding of the virus to ACE2 is the initial step in cellular infection.

ACE2 is part of the renin-angiotensin system (RAS), which plays a crucial role in regulating blood pressure and fluid balance. Research is ongoing to understand the complex interaction between SARS-CoV-2 and ACE2, and how it affects the RAS and contributes to the severity of COVID-19 disease.

3. Consider the following statements : Adenoviruses have single-strand

Consider the following statements :

Adenoviruses have single-stranded DNA genomes whereas retroviruses have double-stranded DNA genomes.
Common cold is sometime caused by an adenovirus whereas AIDS is caused by a retrovirus.

Which of the statements given above is/are correct?

1 only

2 only

Both 1 and 2

Neither 1 nor 2

This question was previously asked in

UPSC IAS – 2021

Download PDF Attempt Online

Statement 1 is incorrect, while statement 2 is correct.

– Statement 1: Adenoviruses are non-enveloped viruses with a *double-stranded* linear DNA genome. Retroviruses are enveloped viruses with a *single-stranded* RNA genome (typically two copies). They are called retroviruses because they use an enzyme called reverse transcriptase to convert their RNA genome into double-stranded DNA after infecting the host cell. Therefore, statement 1 is incorrect.
– Statement 2: Adenoviruses are one of the common causes of the common cold, along with rhinoviruses and coronaviruses. AIDS (Acquired Immunodeficiency Syndrome) is caused by the Human Immunodeficiency Virus (HIV), which is a well-known example of a retrovirus. Therefore, statement 2 is correct.

Adenoviruses can also cause other illnesses like conjunctivitis, bronchitis, and gastroenteritis. HIV primarily infects components of the human immune system, such as CD4+ T cells, macrophages, and dendritic cells, leading to progressive failure of the immune system.

4. Which one of the following statements is not correct?

Which one of the following statements is not correct?

Hepatitis B virus is transmitted much like HIV.

Hepatitis B, unlike Hepatitis C, does not have a vaccine.

Globally, the number of people infected with Hepatitis B and C viruses are several times more than those infected with HIV.

Some of those infected with Hepatitis B and C viruses do not show the symptoms for many years.

This question was previously asked in

UPSC IAS – 2019

Download PDF Attempt Online

The correct option is B because the statement “Hepatitis B, unlike Hepatitis C, does not have a vaccine” is incorrect.

Vaccination is a highly effective way to prevent Hepatitis B infection. While there is no widely available prophylactic vaccine for Hepatitis C, research is ongoing.

A) Hepatitis B and HIV share similar transmission routes, including sexual contact, exposure to infected blood (e.g., through sharing needles), and mother-to-child transmission. This statement is correct.
B) There is a safe and effective vaccine available to prevent Hepatitis B infection. In contrast, there is currently no effective preventive vaccine for Hepatitis C, although treatments for Hepatitis C have significantly advanced. Thus, the statement that Hepatitis B *does not* have a vaccine is false.
C) According to WHO estimates, significantly more people globally live with chronic Hepatitis B and C infections compared to HIV. This statement is correct.
D) Both Hepatitis B and C infections can be asymptomatic for many years, with chronic liver damage occurring silently before symptoms appear. This statement is correct.

5. Consider the following statements: 1. In tropical regions, Zika viru

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?

1 only

2 only

Both 1 and 2

Neither 1 nor 2

This question was previously asked in

UPSC IAS – 2017

Download PDF Attempt Online

Both statements 1 and 2 are correct.

– Statement 1 is correct. Zika virus is primarily transmitted to people through the bite of an infected Aedes species mosquito (Ae. aegypti and Ae. albopictus), which are the same types of mosquitoes that spread dengue, chikungunya, and yellow fever.
– Statement 2 is correct. Zika virus can be transmitted through sexual contact, from an infected person to their partner.

Other modes of Zika virus transmission include transmission from mother to fetus during pregnancy, through blood transfusion (though less common), and potentially through organ transplantation.

6. Which of the following statements is/are correct? Viruses can infect

Which of the following statements is/are correct?
Viruses can infect

bacteria
fungi
plants

Select the correct answer using the code given below.

1 and 2 only

3 only

1 and 3 only

1, 2 and 3

This question was previously asked in

UPSC IAS – 2016

Download PDF Attempt Online

The correct option is D, as viruses can infect bacteria, fungi, and plants.

– Viruses are obligate intracellular parasites that infect a vast range of living organisms across all domains of life.
– Statement 1 is correct: Viruses that infect bacteria are called bacteriophages.
– Statement 2 is correct: Viruses that infect fungi are called mycoviruses.
– Statement 3 is correct: Viruses that infect plants are called plant viruses and cause numerous plant diseases.

Viruses are highly specific in their hosts, with different types of viruses infecting different types of organisms. However, collectively, viruses can infect virtually all forms of cellular life, including bacteria, archaea, protists, fungi, plants, and animals.

7. H1N1 virus is sometimes mentioned in the news with reference to which

H1N1 virus is sometimes mentioned in the news with reference to which one of the following diseases?

AIDS

Bird flu

Dengue

Swine flu

This question was previously asked in

UPSC IAS – 2015

Download PDF Attempt Online

The H1N1 virus is the primary cause of swine flu.

H1N1 is an influenza A virus subtype that is the most common cause of human influenza (flu).

The 2009 swine flu pandemic was caused by a new strain of H1N1 that resulted from a mix of human, swine, and bird flu viruses. While H1N1 strains circulate in various animals, this particular strain was referred to as “swine flu” because genetic analysis showed it originated from pigs. Bird flu is typically caused by other influenza subtypes like H5N1. AIDS is caused by the Human Immunodeficiency Virus (HIV), and Dengue is caused by the Dengue virus, transmitted by mosquitoes.

8. Which of the following statements is/are correct? 1. Viruses lack en

Which of the following statements is/are correct?

1. Viruses lack enzymes necessary for the generation of energy.
2. Viruses can be cultured in any synthetic medium.
3. Viruses are transmitted from one organism to another by biological vectors only.

Select the correct answer using the codes given below.

1 only

2 and 3 only

1 and 3 only

1, 2 and 3

This question was previously asked in

UPSC IAS – 2013

Download PDF Attempt Online

Only statement 1 is correct: Viruses lack enzymes necessary for the generation of energy.

Statement 1 is correct. Viruses are acellular and obligate intracellular parasites. They do not possess their own metabolic machinery, including enzymes for energy production like respiration or fermentation. They hijack the host cell’s metabolic processes to obtain energy and replicate. Statement 2 is incorrect because viruses require living cells to replicate and cannot be cultured in synthetic non-living media. Statement 3 is incorrect because while biological vectors are one mode of transmission for some viruses, many viruses are transmitted through non-vector means such as direct contact, airborne droplets, contaminated surfaces, food, or water.

Viruses consist of genetic material (DNA or RNA) enclosed in a protein coat (capsid), and sometimes an outer envelope derived from the host cell membrane. Their dependence on host cells for replication and metabolism distinguishes them from cellular organisms like bacteria or fungi.

9. Which one of the following statements regarding Zika virus is not corr

Which one of the following statements regarding Zika virus is not correct ?

It was first isolated from a monkey in the Zika forest of Uganda

It is transmitted by daytime-active Aedes mosquitoes

It does not cause mother to child infection

Zika virus in pregnant women results in abnormal brain development of the fetus

This question was previously asked in

UPSC CAPF – 2016

Download PDF Attempt Online

The correct option is C. The statement that Zika virus does not cause mother to child infection is incorrect.

Let’s evaluate each statement:
A) It was first isolated from a monkey in the Zika forest of Uganda: This is correct. The virus was first identified in rhesus monkeys in the Zika Forest of Uganda in 1947 during research on yellow fever.
B) It is transmitted by daytime-active Aedes mosquitoes: This is correct. Zika virus is primarily transmitted by the bite of infected Aedes species mosquitoes, particularly Aedes aegypti, which are known to bite during the day.
C) It does not cause mother to child infection: This is incorrect. Zika virus can be transmitted from a pregnant woman to her fetus during pregnancy or around the time of birth. This is known as congenital Zika syndrome.
D) Zika virus in pregnant women results in abnormal brain development of the fetus: This is correct. Infection during pregnancy, particularly in the first trimester, is strongly linked to microcephaly and other severe brain abnormalities in the developing fetus.

Besides mosquito bites and mother-to-child transmission, Zika virus can also be spread through sexual contact, blood transfusion, and possibly organ transplantation. While symptoms are often mild or absent in adults, the risk to pregnant women and their fetuses is significant.

10. Which of the following is/are the methods of prevention from HIV infec

Which of the following is/are the methods of prevention from HIV infection ?

1. Use of condoms.
2. Use of intra-uterine devices like Copper-T.
3. Staying away from HIV infected person.
4. Using a face mask when in company of HIV infected person.

Select the correct answer using the code given below :

1 and 2 only

3 and 4

1, 2 and 4

1 only

This question was previously asked in

UPSC CAPF – 2010

Download PDF Attempt Online

Among the given options, the use of condoms is a method of prevention from HIV infection.

Using condoms correctly and consistently during sexual activity significantly reduces the risk of HIV transmission. Intra-uterine devices (like Copper-T) are contraceptives and do not prevent HIV or other sexually transmitted infections (STIs). Staying away from an HIV-infected person is not necessary for prevention as HIV is not transmitted through casual contact. Using a face mask is irrelevant as HIV is not an airborne virus.

Other effective methods for preventing HIV transmission include abstinence, reducing the number of sexual partners, consistent and correct use of condoms, pre-exposure prophylaxis (PrEP), post-exposure prophylaxis (PEP), using sterile needles for injection, and safe blood transfusion practices. Antiretroviral therapy (ART) can also reduce the viral load in infected individuals to undetectable levels, effectively preventing sexual transmission (Undetectable = Untransmittable, U=U).