Infectious Diseases Practice Questions

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

Anthropozoonoses. **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.

Q: Weil's disease may be transmitted by:

Contact with water contaminated by rat urine. ***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.

Q: Most common widespread zoonotic disease in the world is -

Leptospirosis. ***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.

Q: 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:

Practice proper hand washing. ***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

Q: Hard ticks transmit

All of the options. ***All of the options*** - Hard ticks are vectors for diverse pathogens, including bacteria causing **tick typhus**, viruses leading to **viral encephalitis**, and the **Kyasanur Forest Disease (KFD)** virus. - Their biting mechanism and feeding habits facilitate the transmission of multiple diseases simultaneously or sequentially. *Tick typhus* - **Tick typhus** (Rocky Mountain spotted fever, Mediterranean spotted fever) is caused by **Rickettsia rickettsii** and other Rickettsia species, which are transmitted by hard ticks. - Symptoms include fever, headache, and a characteristic rash, which are spread by hard ticks like *Dermacentor* and *Rhipicephalus* species. *Viral encephalitis* - Several **encephalitic viruses**, such as **Tick-borne encephalitis virus (TBEV)**, are transmitted by hard ticks (e.g., *Ixodes* species), leading to neurological symptoms. - The virus primarily affects the central nervous system, causing inflammation of the brain. *KFD* - **Kyasanur Forest Disease (KFD)** is a **viral hemorrhagic fever** endemic to India, specifically transmitted by hard ticks (e.g., *Haemaphysalis spinigera*). - It causes high fever, headache, muscle pain, and can lead to severe gastrointestinal bleeding and neurological manifestations.

Q: Post-exposure prophylaxis is indicated in?

All of the options. ***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.

Q: Which of the following is false regarding dracunculiasis?

Niridazole prevents transmission. ***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.

Q: The main vector of Dengue fever is -

Aedes aegypti. ***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.

Q: Chemoprophylaxis can be done for the following except:

Typhoid fever. ***Typhoid fever*** - **Typhoid fever** is primarily controlled through **vaccination** (Vi polysaccharide vaccine, Ty21a oral vaccine) and **improved sanitation** (safe water supply, proper sewage disposal). - **Chemoprophylaxis is NOT routinely recommended** for typhoid fever, even for travelers to endemic areas. Vaccination and food/water precautions are the mainstay of prevention. - Unlike other diseases requiring post-exposure prophylaxis, typhoid contacts are monitored rather than given prophylactic antibiotics. *Meningococcal meningitis* - **Chemoprophylaxis is essential** for close contacts of meningococcal disease cases. - **Rifampicin, ciprofloxacin, or ceftriaxone** are given to household contacts, healthcare workers exposed to respiratory secretions, and other close contacts. - This prevents secondary cases and interrupts transmission in high-risk individuals. *Cholera* - During cholera outbreaks, **chemoprophylaxis with doxycycline or azithromycin** may be used for household contacts and high-risk groups. - This is a **targeted intervention** during acute public health emergencies to prevent rapid spread. - Not routine, but justified in outbreak settings when transmission risk is high. *Influenza* - **Chemoprophylaxis with oseltamivir or zanamivir** is recommended for high-risk unvaccinated individuals exposed to confirmed influenza cases. - Used in institutional outbreaks, for immunocompromised patients, and during the window period before vaccine takes effect. - Particularly important when circulating strain doesn't match vaccine or vaccine is contraindicated.

Q: Animal to man transmission (zoonosis) is seen in -

Rabies. ***Rabies*** - **Rabies** is a classic zoonotic disease, primarily transmitted to humans through the bite or scratch of an infected animal, most commonly **dogs, bats, or other wild carnivores**. - The virus travels from the site of infection to the central nervous system, leading to characteristic neurological symptoms. *Tuberculosis* - While certain strains of **Mycobacterium bovis** can cause zoonotic tuberculosis, the question implies common human tuberculosis (**Mycobacterium tuberculosis**), which is primarily transmitted person-to-person via airborne droplets. - While bovine TB is zoonotic, general "Tuberculosis" in this context usually refers to the human-to-human transmitted form. *Measles* - **Measles** is a highly contagious disease caused by the **measles virus**, which is a **human paramyxovirus**. - It is spread exclusively from **person to person** through respiratory droplets and has no known animal reservoir. *HIV* - **HIV (Human Immunodeficiency Virus)** is thought to have originated from **simian immunodeficiency virus (SIV)** in non-human primates, thus representing a historic zoonotic jump. - However, current and continued transmission of HIV is almost exclusively through **human-to-human contact**, not ongoing animal-to-human transmission.

Question 1

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

Accepted Answer

Anthropozoonoses

Answer

Epizootic

Answer

Zooanthroposes

Answer

Amphixenoses

Question 2

Weil's disease may be transmitted by:

Accepted Answer

Contact with water contaminated by rat urine

Answer

Rat flea bite

Answer

Respiratory route through secretion of patients

Answer

Rat bite

Question 3

Most common widespread zoonotic disease in the world is -

Accepted Answer

Leptospirosis

Answer

Brucellosis

Answer

Rabies

Answer

Anthrax

Question 4

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:

Accepted Answer

Practice proper hand washing

Answer

Disinfect the ward with sodium hypochlorite

Answer

Fumigate the ward

Answer

Give antibiotics to all other patients in the ward

Question 5

Hard ticks transmit

Accepted Answer

All of the options

Answer

Tick typhus

Answer

Viral encephalitis

Answer

KFD

Question 6

Post-exposure prophylaxis is indicated in?

Accepted Answer

All of the options

Answer

Rabies

Answer

Diphtheria

Answer

HBV

Question 7

Which of the following is false regarding dracunculiasis?

Accepted Answer

Niridazole prevents transmission

Answer

No animal reservoir has been proven

Answer

India has eliminated the disease

Answer

Disease is limited to tropical and subtropical regions

Question 8

The main vector of Dengue fever is -

Accepted Answer

Aedes aegypti

Answer

Aedes polynesiensis

Answer

Aedes albopictus

Answer

Aedes scutellaris

Question 9

Chemoprophylaxis can be done for the following except:

Accepted Answer

Typhoid fever

Answer

Meningococcal meningitis

Answer

Cholera

Answer

Influenza

Question 10

Animal to man transmission (zoonosis) is seen in -

Accepted Answer

Rabies

Answer

Tuberculosis

Answer

Measles

Answer

HIV

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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