Climate Change and Infectious Diseases — MCQs
All of the following are true about dengue fever except:
Which disease comes under International Surveillance?
Patient: fever, joint pain, rash. Recent history of mosquito bite. Most likely diagnosis in urban area?
Most important vector for Lyme disease transmission is -
True regarding Japanese encephalitis is except -
Which of the following viral diseases is least commonly reported in India?
Which of the following diseases is not under surveillance in the Integrated Disease Surveillance Project (P-Form)?
Germ theory of disease causation is given by:
The following hormonal changes mark the Polycystic Ovarian Disease except
Which organism does not require a vector for transmission?
Climate Change and Infectious Diseases Indian Medical PG Practice Questions and MCQs
Question 1: All of the following are true about dengue fever except:
- A. Thrombocytosis (Correct Answer)
- B. Elevated hematocrit
- C. Transmitted by Aedes
- D. Also called as breakbone fever
Explanation: ***Thrombocytosis*** - **Thrombocytosis** (elevated platelet count) is generally **not true** in dengue fever; instead, **thrombocytopenia** (low platelet count) is a characteristic feature and a marker of disease severity. [1] - A significant drop in platelet count often necessitates monitoring and can be an indicator of impending **dengue hemorrhagic fever**. [1] *Elevated hematocrit* - **Elevated hematocrit** is a significant finding in severe dengue, indicating **plasma leakage** due to increased vascular permeability. [1] - This suggests **hemoconcentration** and is a key criterion for defining **dengue hemorrhagic fever**. *Transmitted by Aedes* - Dengue fever is primarily transmitted by the **Aedes aegypti** mosquito, and less commonly by **Aedes albopictus**. - These mosquitoes are **day-biting** and thrive in urban environments with stagnant water. *Also called as breakbone fever* - Dengue fever is commonly known as **"breakbone fever"** due to the severe generalized **myalgia** and **arthralgia** that can accompany the infection. [1] - Patients often experience **intense muscle and joint pain**, making movement very painful.
Question 2: Which disease comes under International Surveillance?
- A. Typhoid fever (Correct Answer)
- B. Chikungunya fever
- C. Hepatitis B
- D. Salmonellosis
Explanation: ***Typhoid fever*** - **Typhoid fever** is monitored by the **World Health Organization (WHO)** through global surveillance systems to track incidence, guide vaccination strategies, and implement control measures. - While **not on the mandatory notification list** under the International Health Regulations (IHR) 2005, typhoid is included in **WHO's global disease surveillance** programs due to its significant disease burden in endemic regions. - Among the given options, typhoid fever has the **strongest international surveillance framework** through WHO's Global Foodborne Infections Network and regional surveillance systems. - **Note:** Diseases under **mandatory IHR surveillance** include cholera, plague, yellow fever, smallpox, poliomyelitis, SARS, and novel influenza subtypes. *Chikungunya fever* - Chikungunya is primarily monitored through **national and regional surveillance** systems rather than comprehensive international surveillance frameworks. - WHO tracks outbreaks through epidemic intelligence but it is **not part of mandatory IHR notification**. - Surveillance focuses on **vector control** and outbreak detection at local levels. *Hepatitis B* - **Hepatitis B** surveillance is conducted primarily at **national levels** through prevalence studies, vaccination coverage monitoring, and chronic infection programs. - It is **not under mandatory international surveillance** per IHR, though WHO maintains global estimates and monitoring frameworks. - Focus is on **prevention through vaccination** and treatment of chronic infections. *Salmonellosis* - Non-typhoidal **salmonellosis** is monitored mainly through **national food safety** and public health surveillance systems. - **Not designated for mandatory international surveillance** under IHR 2005. - International coordination occurs through networks like WHO's Global Foodborne Infections Network for outbreak investigation.
Question 3: Patient: fever, joint pain, rash. Recent history of mosquito bite. Most likely diagnosis in urban area?
- A. Dengue
- B. Japanese Encephalitis
- C. Malaria
- D. Chikungunya (Correct Answer)
Explanation: ***Chikungunya*** - **Chikungunya** is a viral disease transmitted by mosquitoes that commonly presents with **fever**, severe **joint pain** (polyarthralgia), and a **rash**, fitting the patient's symptoms. - Its high prevalence in **urban areas** and recent history of **mosquito bites** make it a strong diagnostic consideration. *Dengue* - While Dengue also causes **fever** [1] and a **rash**, it is more typically associated with **severe muscle and bone pain** ("breakbone fever"), and **hemorrhagic manifestations** or shock, which are not mentioned. - **Joint pain** in dengue is usually less debilitating than in chikungunya. *Japanese Encephalitis* - This is a serious **neurological infection** characterized by **fever**, **headache**, seizures, and altered mental status, rather than prominent joint pain and rash. - It primarily affects the **brain** and is less likely to present with this specific symptom triad. *Malaria* - Malaria is characterized by **cyclic fevers**, chills, sweating, and fatigue, but typically **does not present with a rash** [1] or significant joint pain. - It is caused by a **parasite** transmitted by *Anopheles* mosquitoes, and its clinical picture differs from the described symptoms.
Question 4: Most important vector for Lyme disease transmission is -
- A. Rat flea
- B. Sand fly
- C. Mosquito
- D. Ticks (Correct Answer)
Explanation: ***Ticks*** - **Lyme disease** is caused by the bacterium *Borrelia burgdorferi* and is primarily transmitted to humans through the bite of infected black-legged ticks, also known as **deer ticks** (*Ixodes scapularis* in the eastern and midwestern U.S., and *Ixodes pacificus* in the Pacific Coast). - Ticks are the **definitive vector** for Lyme disease, serving as both a reservoir and a means of transmission. *Rat flea* - **Rat fleas** (*Xenopsylla cheopis*) are primarily known as vectors for diseases such as **bubonic plague** (caused by *Yersinia pestis*) and **murine typhus** (caused by *Rickettsia typhi*). - They are not associated with the transmission of Lyme disease. *Sand fly* - **Sand flies** (e.g., *Phlebotomus* species) are vectors for diseases such as **leishmaniasis**, **sandfly fever**, and **Bartonellosis**. - They are not responsible for transmitting *Borrelia burgdorferi* or Lyme disease. *Mosquito* - **Mosquitoes** are significant vectors for numerous diseases including **malaria**, **dengue fever**, **Zika virus**, and **West Nile virus**. - While they transmit many pathogens, mosquitoes do not transmit the bacteria responsible for Lyme disease.
Question 5: True regarding Japanese encephalitis is except -
- A. The iceberg phenomenon is observed.
- B. Human-to-human transmission is not reported.
- C. Mortality is 80-90%. (Correct Answer)
- D. Culicine mosquitoes are zoophilic.
Explanation: ***Mortality is 80-90%.*** - The **mortality rate** for Japanese encephalitis is generally reported between **20-30%** among symptomatic cases, particularly in children. - A mortality rate of 80-90% is excessively high and **inaccurate** for Japanese encephalitis. *The iceberg phenomenon is observed.* - The **iceberg phenomenon** is characteristic of Japanese encephalitis, meaning that for every symptomatic case, there are many **asymptomatic infections** that go undetected. - Only a small proportion of infected individuals develop severe neurological disease, while the majority remain subclinical. *Human-to-human transmission is not reported.* - Japanese encephalitis is a **vector-borne disease** transmitted primarily by mosquitoes; it is **not transmitted directly** from person to person. - The virus circulates between mosquitoes, amplifying hosts (like pigs), and humans are typically dead-end hosts. *Culicine mosquitoes are zoophilic.* - **Culicine mosquitoes**, particularly *Culex tritaeniorhynchus*, are the primary vectors and are indeed **zoophilic**, meaning they prefer to feed on animals (like pigs and wading birds). - This zoophilic nature contributes to the amplification cycle of the virus in animal reservoirs before humans are incidentally bitten.
Question 6: Which of the following viral diseases is least commonly reported in India?
- A. Japanese B encephalitis
- B. Lassa fever (Correct Answer)
- C. KFD
- D. Dengue
Explanation: ***Lassa fever*** - **Lassa fever** is endemic to West Africa, with the **multimammate rat** being its primary reservoir. - Cases of Lassa fever are **extremely rare** in India, primarily limited to travel-related instances due to the geographical distribution of the disease and its vector. *Japanese B encephalitis* - **Japanese B encephalitis (JBE)** is a significant public health concern in India, particularly in endemic regions. - It is a mosquito-borne viral disease, and **vaccination programs** are ongoing to control its spread. *KFD* - **Kyasanur Forest Disease (KFD)** is an endemic viral hemorrhagic fever primarily found in the **Karnataka state of India**. - It is transmitted by **ticks**, making it a regionally significant but recognized viral disease within India. *Dengue* - **Dengue** is one of the most commonly reported and widespread viral diseases in India. - It is a **mosquito-borne** illness with frequent outbreaks occurring across various parts of the country.
Question 7: Which of the following diseases is not under surveillance in the Integrated Disease Surveillance Project (P-Form)?
- A. Snake bite (Correct Answer)
- B. Acute respiratory tract infections
- C. Tuberculosis
- D. Leptospirosis
Explanation: ***Snake bite*** - While a public health concern, **snake bites** are generally not included in the list of diseases under routine surveillance by the Integrated Disease Surveillance Project (IDSP) P-Form, which focuses on infectious diseases with epidemic potential. - The IDSP primarily monitors for **communicable diseases**, outbreaks, and other public health threats requiring rapid detection and response. *Acute respiratory tract infections* - **Acute respiratory tract infections (ARIs)**, including severe acute respiratory infections (SARIs), are a major focus of IDSP surveillance due to their high transmissibility and potential for large-scale outbreaks. - Surveillance helps in detecting trends, identifying new pathogens, and implementing timely control measures. *Tuberculosis* - **Tuberculosis (TB)** is a priority disease for surveillance under the IDSP due to its high prevalence, chronic nature, and the need for continuous monitoring of incidence, prevalence, and treatment outcomes. - The IDSP plays a role in tracking TB cases and drug resistance patterns to inform national control programs. *Leptospirosis* - **Leptospirosis** is an emerging infectious disease with epidemic potential, especially in areas with poor sanitation and during floods, making it a crucial disease for IDSP surveillance. - Surveillance helps in early detection of outbreaks and implementation of control measures to prevent spread.
Question 8: Germ theory of disease causation is given by:
- A. Pettenkofer
- B. Robert Koch
- C. Aristotle
- D. Louis Pasteur (Correct Answer)
Explanation: ***Louis Pasteur*** - **Louis Pasteur** was a French chemist and microbiologist renowned for his groundbreaking work in preventing diseases. - He is often regarded as the "father of microbiology" and **germ theory**, as he demonstrated that microorganisms cause fermentation and putrefaction. *Pettenkofer* - **Max von Pettenkofer** was a prominent German hygienist who, despite his contributions to public health, was a vocal opponent of the germ theory. - He famously challenged Robert Koch's findings and even ingested cholera bacteria to prove his belief that environmental factors, not germs, were the primary cause of disease. *Robert Koch* - **Robert Koch** was a German physician and microbiologist who built upon Pasteur's germ theory by providing irrefutable evidence linking specific microorganisms to specific diseases. - He developed **Koch's postulates**, a set of criteria used to establish a causal relationship between a microbe and a disease, and identified the causative agents of anthrax, tuberculosis, and cholera. *Aristotle* - **Aristotle** was an ancient Greek philosopher and polymath who made significant contributions to various fields. - While his ideas profoundly influenced Western thought and natural sciences, he lived centuries before the concept of microorganisms was discovered and therefore did not formulate the germ theory of disease.
Question 9: The following hormonal changes mark the Polycystic Ovarian Disease except
- A. Raised LH, Low-to-normal FSH
- B. Hyperinsulinaemia
- C. Raised LH, Raised FSH (Correct Answer)
- D. Hyperandrogenism
Explanation: ***Raised LH, Raised FSH*** - In **Polycystic Ovarian Syndrome (PCOS)**, the characteristic LH/FSH ratio is typically **high LH and low-to-normal FSH**, not elevated levels of both. - A simultaneous elevation of both **LH and FSH** is more indicative of **primary ovarian failure** rather than PCOS, as the ovaries would no longer be producing sufficient hormones, leading to increased pituitary stimulation. *Raised LH, Low-to-normal FSH* - This hormonal pattern is a hallmark of **PCOS**, where the **increased LH** stimulates the ovarian theca cells to produce excess androgens. - The **low or normal FSH** prevents proper follicular development, contributing to anovulation and cyst formation. *Hyperinsulinaemia* - **Insulin resistance** and compensatory **hyperinsulinaemia** are very common findings in PCOS, driving increased ovarian androgen production. - High insulin levels potentiate the effect of LH on ovarian androgen synthesis and suppress hepatic production of sex hormone-binding globulin (SHBG). *Hyperandrogenism* - **Hyperandrogenism**, characterized by elevated levels of androgens (e.g., testosterone), is a central feature of PCOS and responsible for symptoms like hirsutism, acne, and alopecia. - This excess androgen production originates primarily from the ovaries and, to some extent, the adrenal glands, often exacerbated by hyperinsulinaemia.
Question 10: Which organism does not require a vector for transmission?
- A. Rickettsia rickettsii
- B. Borrelia recurrentis
- C. Rickettsia prowazekii
- D. Coxiella burnetii (Correct Answer)
Explanation: ***Coxiella burnetii*** - This organism causes **Q fever** and does not require an arthropod vector; it is primarily transmitted via **aerosols** from infected animals. - Humans usually acquire the infection by inhaling **contaminated aerosols** from infected livestock (cattle, sheep, goats). *Rickettsia prowazekii* - This bacterium is the causative agent of **epidemic typhus** and is transmitted by the **human body louse** (*Pediculus humanus corporis*). - The louse acts as a **biological vector**, acquiring the organism from an infected human and transmitting it through its feces, which are then scratched into the skin. *Rickettsia rickettsii* - This organism causes **Rocky Mountain Spotted Fever (RMSF)** and is transmitted by **ticks**, primarily the American dog tick (*Dermacentor variabilis*) and the Rocky Mountain wood tick (*Dermacentor andersoni*). - Ticks serve as both **vectors** and **reservoirs** for *Rickettsia rickettsii*. *Borrelia recurrentis* - This spirochete causes **louse-borne relapsing fever** and is transmitted by the **human body louse** (*Pediculus humanus corporis*). - Transmission occurs when the louse is crushed and its hemolymph, containing the bacteria, comes into contact with broken skin or mucous membranes.
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