Infectious Diseases — MCQs

Infectious Diseases Indian Medical PG Practice Questions and MCQs

Question 391: All of the following are true statements for Arbovirus EXCEPT:

A. West nile fever is transmitted by Culex mosquito
B. Chikungunya fever is transmitted by Aedes mosquito
C. Kyasanur Forest Disease is transmitted by mites (Correct Answer)
D. Japanese encephalitis is caused by group B Arbovirus (Flavivirus)

Explanation: ***Kyasanur Forest Disease is transmitted by mites*** - This statement is **false**. Kyasanur Forest Disease (KFD) is transmitted by **ticks**, specifically the *Haemaphysalis spinigera* tick, not mites. - KFD is a **tick-borne viral hemorrhagic fever** endemic to certain regions of India, caused by a flavivirus. *West nile fever is transmitted by Culex mosquito* - This statement is **true**. **West Nile virus** is primarily transmitted to humans through the bite of infected mosquitos, mainly species of **Culex**. - The virus circulates naturally between mosquitos and **birds**, with humans being incidental hosts. *Chikungunya fever is transmitted by Aedes mosquito* - This statement is **true**. **Chikungunya virus** is transmitted to humans through the bites of infected female mosquitos, primarily **Aedes aegypti** and **Aedes albopictus**. - These mosquitos are also vectors for other diseases such as dengue and Zika. *Japanese encephalitis is caused by group B Arbovirus (Flavivirus)* - This statement is **true**. Japanese encephalitis is caused by the **Japanese encephalitis virus (JEV)**, which belongs to the **Flaviviridae family**, often referred to as group B Arboviruses. - Most human infections are asymptomatic, but severe cases can lead to **encephalitis** with high mortality.

Question 392: Reduvid bug transmits-

A. Trench fever
B. Relapsing fever
C. Chagas disease (Correct Answer)
D. Kala-azar

Explanation: ***Correct Option: Chagas disease*** - Chagas disease, or **American trypanosomiasis**, is caused by the parasite **Trypanosoma cruzi**, which is transmitted to humans by the fecal contamination from the **triatomine bug** (reduviid bug or "kissing bug"). - The bug typically bites on the face during sleep, defecating nearby, and the parasite enters the body when the person rubs the feces into the bite wound, mucous membranes, or eyes. *Incorrect Option: Trench fever* - Trench fever is caused by the bacterium **Bartonella quintana** and is transmitted by the **human body louse (Pediculus humanus corporis)**, not the reduviid bug. - Symptoms include recurrent fever, headache, and shin pain, common during wartime conditions. *Incorrect Option: Relapsing fever* - Relapsing fever is caused by various species of **Borrelia bacteria** and is transmitted by **ticks (tick-borne relapsing fever)** or **lice (louse-borne relapsing fever)**. - It is characterized by recurrent episodes of fever, headache, muscle, and joint aches, with asymptomatic periods in between. *Incorrect Option: Kala-azar* - Kala-azar, or **visceral leishmaniasis**, is caused by **Leishmania donovani** and is transmitted by the bite of infected **sandflies (Phlebotomus argentipes in India)**. - It is a systemic disease affecting internal organs like the spleen, liver, and bone marrow, leading to fever, weight loss, and hepatosplenomegaly.

Question 393: What is the color of Kit 3 for STD management under the AIDS Control Programme?

A. Blue
B. White
C. Green (Correct Answer)
D. Red

Explanation: ***Green*** - Under the **AIDS Control Programme**, the **National AIDS Control Organization (NACO)** standardizes treatment for STDs using syndromic management kits. - **Kit 3**, designated for the management of **vaginal discharge syndrome** in women, is identified by its **green** color. *Blue* - **Blue** is the color assigned to **Kit 1**, which is used for the syndromic management of **urethral discharge in men**. - This kit focuses on common causes of urethral inflammation and discharge. *White* - **White** is the color for **Kit 4**, which is used for the syndromic management of **genital ulcer disease without inguinal adenopathy**. - This kit often contains treatments for syphilis and chancroid. *Red* - **Red** is the color designated for **Kit 2**, which is used for the syndromic management of **genital ulcer disease with inguinal bubo**. - This kit typically includes treatments for conditions like lymphogranuloma venereum or severe chancroid.

Question 394: When a disease spreads from vertebrate animals to man it is said to be:

A. Epizootic
B. Zooanthroposes
C. Anthropozoonoses (Correct Answer)
D. Amphixenoses

Explanation: **Anthropozoonoses** - This term specifically describes diseases that are naturally transmissible from **vertebrate animals** to humans. - Examples include diseases like **rabies**, **Lyme disease**, and many types of influenza. *Epizootic* - This term refers to an outbreak of disease in an **animal population** (similar to an epidemic in humans). - It does not specifically imply transmission to humans. *Zooanthroposes* - This is not a standard medical or veterinary term used to describe disease transmission. - The correct term for animal-to-human transmission is **anthropozoonoses**. *Amphixenoses* - This term refers to diseases that are maintained in both **animal and human populations**, capable of transmission in either direction. - It implies a two-way or cyclical transmission, whereas the question specifically asks about **animal-to-human** spread.

Question 395: Weil's disease may be transmitted by:

A. Contact with water contaminated by rat urine (Correct Answer)
B. Rat flea bite
C. Respiratory route through secretion of patients
D. Rat bite

Explanation: ***Contact with water contaminated by rat urine*** - **Weil's disease** is a severe form of **leptospirosis**, caused by bacteria often shed in the urine of infected animals, particularly rats. - Humans become infected through contact with **contaminated water** or soil, where the bacteria can enter through skin abrasions or mucous membranes. *Rat flea bite* - **Rat flea bites** are the primary mode of transmission for diseases like **bubonic plague** (caused by *Yersinia pestis*) and **murine typhus** (caused by *Rickettsia typhi*). - These conditions are distinct from leptospirosis, caused by bacteria of the genus *Leptospira*. *Respiratory route through secretion of patients* - Transmission via the **respiratory route** or **person-to-person spread** through patient secretions is characteristic of viral infections such as **influenza** or **tuberculosis**. - **Weil's disease** is not typically spread from person to person through these means. *Rat bite* - **Rat bites** can transmit various pathogens, leading to **rat-bite fever**, which can be caused by *Spirillum minus* or *Streptobacillus moniliformis*. - While rats are carriers of *Leptospira*, direct rat bites are not the common way humans acquire Weil's disease; exposure to contaminated environments is the primary route.

Question 396: Most common widespread zoonotic disease in the world is -

A. Leptospirosis (Correct Answer)
B. Brucellosis
C. Rabies
D. Anthrax

Explanation: ***Leptospirosis*** - **Leptospirosis** is considered the most common widespread **zoonotic disease** globally, with an estimated 1.03 million cases per year. - It is caused by **spirochetes** of the genus *Leptospira* and is transmitted to humans through contact with urine from infected animals or contaminated water/soil. *Brucellosis* - **Brucellosis** is a significant zoonotic disease but is generally less widespread than leptospirosis, particularly in regions with effective control programs for livestock. - It is transmitted through direct contact with infected animals or consumption of unpasteurized dairy products, often causing **undulant fever**. *Rabies* - **Rabies** is a severe and nearly universally fatal zoonotic disease, but its global incidence is lower than leptospirosis, largely due to successful vaccination campaigns in animals. - Transmission occurs primarily through the bite of an infected animal, leading to **neurological symptoms**. *Anthrax* - **Anthrax** is a serious bacterial disease, but its occurrence is relatively rare and often localized to specific regions or outbreak events. - It is caused by *Bacillus anthracis* and is typically acquired through contact with infected animals or their products, presenting in **cutaneous**, **inhalational**, **gastrointestinal**, or **injectional** forms.

Question 397: In postoperative intensive care unit, five patients developed postoperative wound infection on the same day. The best method to prevent cross infection occurring in other patients in the same ward is to:

A. Practice proper hand washing (Correct Answer)
B. Disinfect the ward with sodium hypochlorite
C. Fumigate the ward
D. Give antibiotics to all other patients in the ward

Explanation: ***Correct: Practice proper hand washing*** - **Proper hand hygiene** is the **single most effective method** for preventing the transmission of **healthcare-associated infections (HAIs)**, including surgical site infections - It physically removes or inactivates **transient microorganisms** from the hands of healthcare workers, thereby stopping their spread between patients - This is the **gold standard** recommended by **WHO, CDC**, and all major infection control guidelines for preventing **cross-infection** in healthcare settings *Incorrect: Disinfect the ward with sodium hypochlorite* - While disinfection with **sodium hypochlorite** is important for **environmental cleaning**, it is **less effective than hand hygiene** in preventing direct patient-to-patient transmission - Environmental disinfection alone **cannot interrupt the main routes of transmission**, which often involve **direct contact** or contaminated hands of healthcare personnel - This is a **secondary measure**, not the primary prevention strategy *Incorrect: Fumigate the ward* - **Fumigation** is typically used for **terminal disinfection** in specific situations, such as after highly contagious outbreaks, and is **not a routine** or primary method for preventing cross-infection in an active ward - Its effectiveness in preventing day-to-day cross-infection is **limited compared to immediate infection control practices** like hand hygiene - This practice is largely **outdated** in modern infection control protocols *Incorrect: Give antibiotics to all other patients in the ward* - **Prophylactic antibiotic use** in all other patients is **discouraged** due to the risk of **antimicrobial resistance (AMR)** and potential adverse effects - It does **not address the source of infection** or the transmission pathways, and can lead to wider public health issues - This is an **inappropriate primary prevention strategy** that violates antimicrobial stewardship principles

Question 398: Post-exposure prophylaxis is indicated in?

A. Rabies
B. Diphtheria
C. HBV
D. All of the options (Correct Answer)

Explanation: ***All of the options*** - Post-exposure prophylaxis (PEP) is a critical intervention for various infectious diseases, including **Rabies**, **Diphtheria**, and **HBV**, to prevent disease development after exposure. - The specific PEP regimen varies by disease but generally involves **vaccines**, **immunoglobulins**, or **antiviral medications**. **Rabies PEP:** - Rabies PEP is indicated after potential exposure to a rabid animal and involves a series of **rabies vaccine** doses and, for unvaccinated individuals, **rabies immune globulin (RIG)**. - Rabies is almost always fatal once symptoms appear, making timely PEP crucial. **Diphtheria PEP:** - Diphtheria PEP is recommended for close contacts of individuals with confirmed diphtheria and typically involves administering a **booster dose of diphtheria toxoid vaccine** and sometimes **antibiotics**. - This helps prevent the spread of *Corynebacterium diphtheriae* and disease development in exposed individuals. **HBV PEP:** - HBV PEP is critical after percutaneous or mucosal exposure to **HBV-infected blood** or body fluids. - It usually includes administering **hepatitis B vaccine** and, in some cases, **hepatitis B immune globulin (HBIG)**, depending on the exposed person's vaccination status and the source's HBV status.

Question 399: Which of the following is false regarding dracunculiasis?

A. No animal reservoir has been proven
B. Niridazole prevents transmission (Correct Answer)
C. India has eliminated the disease
D. Disease is limited to tropical and subtropical regions

Explanation: ***Niridazole prevents transmission*** - **This is FALSE** - Niridazole is an antiparasitic drug that was used for schistosomiasis and other parasitic infections, but it has **no role in dracunculiasis** treatment or prevention. - **No drug prevents transmission** of dracunculiasis; prevention relies entirely on **safe drinking water practices**, filtering water through cloth filters, treating water sources, and health education. - This is the **most clearly false statement** among the options. *No animal reservoir has been proven* - This statement was historically considered true but is now **outdated and controversial**. - Recent discoveries (particularly in Chad since 2012) have identified **animal infections** in dogs, cats, and baboons with *Dracunculus* species. - However, this statement is less definitively false than the niridazole option, as the animal reservoir debate continues in eradication efforts. *India has eliminated the disease* - This is **TRUE** - India was certified by the WHO as having **eliminated dracunculiasis in 2000** after a successful national eradication program. - India achieved this through active case surveillance, health education, provision of safe drinking water, and community mobilization. *Disease is limited to tropical and subtropical regions* - This is **TRUE** - Dracunculiasis occurs predominantly in **rural, impoverished areas of tropical and subtropical Africa**. - The parasite's life cycle requires **copepods (water fleas)** in stagnant water sources, which thrive in warm climates typical of these regions.

Question 400: The main vector of Dengue fever is -

A. Aedes polynesiensis
B. Aedes aegypti (Correct Answer)
C. Aedes albopictus
D. Aedes scutellaris

Explanation: ***Aedes aegypti*** - This mosquito is the **primary vector** for Dengue, as well as Zika, yellow fever, and chikungunya viruses, transmitting them to humans. - It is highly adapted to urban environments and typically bites during the **daytime**. *Aedes polynesiensis* - While an *Aedes* species, it is primarily known as a vector for **lymphatic filariasis** in the South Pacific. - Less commonly associated with Dengue transmission compared to *Aedes aegypti*. *Aedes albopictus* - Known as the **Asian tiger mosquito**, it is a competent vector for Dengue but is considered a **secondary vector** globally. - Its geographic range is expanding, leading to increased concern about its role in arbovirus transmission. *Aedes scutellaris* - This species is a vector for **lymphatic filariasis** and other arboviruses in specific regions, particularly in parts of Oceania. - It is not considered a primary or major vector for Dengue fever on a global scale.

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