Infectious Diseases Practice Questions

Q: All of the following are true about dengue fever except:

Thrombocytosis. ***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.

Q: Female treated for Urinary tract infection now has vaginal discharge. The most likely organism is?

Candida. ***Candida*** - Antibiotic treatment for a **urinary tract infection** can disrupt the normal vaginal flora, leading to an overgrowth of **Candida albicans**, which is a common cause of vaginal discharge. - This often presents as **vulvovaginal candidiasis** with thick, white, "cottage cheese-like" discharge and intense pruritus. *Trichomonas* - **Trichomonas vaginalis** is a sexually transmitted infection (STI) that causes greenish-yellow, frothy vaginal discharge with a foul odor [1]. - While it can cause vaginal discharge, it is less likely to be directly precipitated by antibiotic use for a UTI compared to candidiasis. *Ureaplasma urealyticum* - **Ureaplasma urealyticum** can cause non-gonococcal urethritis and cervicitis, and sometimes vaginal discharge, but it is not typically associated with a flare-up following antibiotic treatment for a UTI. - It is often considered part of the normal genitourinary flora or an opportunistic pathogen. *Chlamydia* - **Chlamydia trachomatis** is a common sexually transmitted bacterium [2] that can cause cervicitis, leading to vaginal discharge, often mucopurulent and subtle [1]. - It would not typically emerge as a direct consequence or overgrowth due to antibiotic treatment for a UTI, unlike fungal infections.

Q: A 20-year-old woman presents with headache, fever, and neck stiffness. On examination, her blood pressure is 100/70 mm Hg, pulse 100/min, temperature 38.6, and the neck is stiff and painful to flex and extend. The ears, throat, and sinuses are normal, there are no focal neurologic signs, and the remaining examination is normal. There are no reported similar cases in the community. Which of the following is the most likely source of her infection?

nasopharynx. ***Nasopharynx*** - The nasopharynx is a common reservoir for **meningitis-causing bacteria** such as *Neisseria meningitidis* and *Streptococcus pneumoniae*. - These bacteria can colonize the nasopharynx without causing local illness and then cross the mucosal barrier to enter the bloodstream, eventually reaching the **meninges**. *Skin* - Skin infections typically cause **localized symptoms** such as redness, swelling, and pain, possibly with pus formation. - While skin infections can lead to bacteremia and distant infections, there are no skin lesions or signs of infection mentioned in this case. *Oral ingestion* - Oral ingestion typically leads to **gastrointestinal symptoms** such as nausea, vomiting, or diarrhea. - While some pathogens ingested orally can spread systemically, it is not the most direct or common route for the symptoms described. *An infected heart valve* - An infected heart valve (endocarditis) would commonly present with **new heart murmurs**, **constitutional symptoms** (fever, fatigue), and signs of **embolism**, which are not mentioned here [1]. - While endocarditis can cause bacteremia and systemic spread, it would typically have more distinct cardiac findings. *General Clinical Presentation* - Headache, fever, and neck stiffness (meningism) are the classic presenting features of bacterial meningitis [1].

Q: A farmer presents with multiple dicharging sinuses in the leg not responding to antibiotics. Most likely diagnosis is -

Madurella. ***Madurella*** - This symptom complex, particularly **multiple discharging sinuses** in an agricultural worker not responding to antibiotics, is highly suggestive of **eumycetoma (true mycetoma)**. - **Madurella** species (e.g., *Madurella mycetomatis*) are the most common cause of eumycetoma, which is characterized by chronic subcutaneous infection with discharge of **grains** containing fungal elements. *Nocardia* - **Nocardia** causes **actinomycetoma**, which also presents with discharging sinuses and grains but is caused by filamentous bacteria, not fungi. - While *Nocardia* can produce similar lesions, the distinction often requires microscopic examination of the grains or culture, and the context often points to true fungi in geographical areas where Madurella is prevalent. *Actino-mycetoma* - **Actinomycetoma** refers to mycetoma caused by **filamentous bacteria** (e.g., *Nocardia, Actinomadura, Streptomyces*), which produces different types of grains and responds to different antibiotic regimens. - The question implies a lack of response to typical antibiotics, subtly suggesting a fungal etiology which is generally less responsive to standard antibacterial treatments. *Sporothrix* - **Sporothrix schenckii** causes **sporotrichosis**, which typically presents as a **lymphocutaneous infection** with a primary lesion that may ulcerate and spread along lymphatic channels, rather than extensive, chronic discharging sinuses with grains characteristic of mycetoma. - While it can occur in agricultural workers due to inoculated trauma (e.g., thorn pricks), its clinical presentation is distinct from mycetoma.

Q: Meyers Kouwenaar syndrome is a synonym for ?

Occult filariasis. ***Occult filariasis*** - **Meyers Kouwenaar syndrome** is a historical term used to describe **occult filariasis**, particularly those cases involving the lymphatics without the presence of microfilariae in peripheral blood. - This syndrome is characterized by **chronic lymphatic obstruction** and **eosinophilia**, often due to an immunological response to filarial antigens. *Larva migrans* - **Larva migrans** refers to conditions (cutaneous or visceral) caused by the migration of **nematode larvae** in human tissues. - It describes the migratory phase of the parasite and is not a synonym for occult filariasis, which is a specific clinical manifestation of filarial infection. *Tropical pulmonary eosinophilia* - **Tropical pulmonary eosinophilia (TPE)** is a distinct clinical syndrome characterized by **nocturnal cough**, **dyspnea**, and **marked peripheral eosinophilia**, caused by an allergic reaction to Wuchereria bancrofti or Brugia malayi microfilariae that are trapped in the lungs. - While it is a form of occult filariasis (microfilariae are absent in the blood), it is a specific presentation and not a general synonym for Meyers Kouwenaar syndrome, which typically refers to lymphatic involvement. *Cutaneous allergic reactions to Ascariasis* - **Cutaneous allergic reactions to Ascariasis** typically involve manifestations like **urticaria** or **angioedema** due to migration of Ascaris larvae or exposure to adult worms. - This is a reaction to a different parasitic infection (Ascaris lumbricoides) and does not relate to filariasis.

Q: Acquired megacolon can be due to

Chagas disease. ***Chagas disease*** - **Chagas disease** (caused by *Trypanosoma cruzi*) can destroy the **enteric nervous system** in the colon, leading to **megacolon** due to loss of motor neurons. - This destruction impairs colonic motility, causing stasis of fecal material, dilatation, and functional obstruction. *Typhoid* - **Typhoid fever** is caused by *Salmonella typhi* and primarily affects the small intestine and lymphoid tissue, potentially leading to **ulceration and hemorrhage** [2]. - While it can cause gastrointestinal symptoms, it does not typically result in **megacolon** as a direct complication. *Leishmaniasis* - **Leishmaniasis** is caused by *Leishmania* parasites and typically manifests as cutaneous, mucocutaneous, or visceral forms. - It primarily affects the skin, mucous membranes, or internal organs (spleen, liver, bone marrow) and is not associated with **megacolon**. *Amoebiasis* - **Amoebiasis**, caused by *Entamoeba histolytica*, can lead to **colitis, dysentery**, or liver abscesses [1]. - While severe amoebic colitis can rarely lead to **toxic megacolon** due to acute inflammation and paralysis of the colonic wall, it is distinct from the chronic neuropathic changes seen in Chagas disease leading to acquired megacolon.

Q: An otherwise healthy male presents with a creamy curd like white patch on the tongue. The probable diagnosis is

Candidiasis. ***Candidiasis*** - The classic presentation of **oral candidiasis** (thrush) is a **creamy, curd-like white patch** on the mucous membranes, including the tongue, which can often be scraped off. - This common fungal infection, caused by *Candida albicans*, can occur in otherwise healthy individuals, especially after antibiotic use, or with mild immunosuppression. *Histoplasmosis* - This fungal infection is typically associated with **pulmonary involvement** in endemic areas (e.g., Ohio and Mississippi River valleys). - Oral lesions, if present, are usually **firm, nodular, or ulcerative**, not creamy white patches, and often signify disseminated disease in immunocompromised individuals. *Aspergillosis* - Primarily a **pulmonary infection**, especially in immunocompromised patients, with symptoms like fever, cough, and dyspnea. [1] - Oral manifestations are rare and typically present as **necrotic ulcers** or plaques, not creamy white patches, and are usually seen in severely immunocompromised patients. [1] *Lichen Planus* - Oral lichen planus presents with **white reticular (lace-like) patterns** (Wickham's striae), plaques, or erosions on the buccal mucosa, tongue, or gingiva. - These lesions are typically **non-scrapable** and can be associated with pain or burning, differing significantly from the "creamy curd-like" description.

Q: A 22-year-old homeless person with a known drug abuse problem and multiple opportunistic infections has a positive PPD (purified protein) test. Which of the following is the most common way this infection is acquired?

Respiratory tract. ***Respiratory tract*** - **Tuberculosis (TB)**, indicated by a positive PPD, is primarily transmitted via **airborne droplets** generated when an infected person coughs, sneezes, or talks. [1] - The inhaled *Mycobacterium tuberculosis* bacilli then settle in the **lungs**, leading to infection. [1] *GI tract* - While TB can rarely affect the GI tract (e.g., through ingestion of contaminated milk or sputum), it is not the **primary route of acquisition** for pulmonary TB. - The **acidic environment of the stomach** is generally hostile to the bacteria, making this a less common entry point. *Genital tract* - **Genital tuberculosis** is a rare form of extrapulmonary TB and is **not a common route of primary infection** for pulmonary TB. [2] - It usually occurs as a result of **hematogenous dissemination** from a primary pulmonary focus. [2] *Nasal tract* - The nasal tract is part of the upper respiratory system but is not the **primary site of deposition** or infection for *Mycobacterium tuberculosis*. - The bacteria typically travel deeper into the **alveoli of the lungs** to establish infection. [1]

Q: Which of the following is the most common CNS tumor associated with HIV infection?

Lymphoma. ***Lymphoma*** - **Primary CNS lymphoma (PCNSL)** is the most common CNS tumor observed in patients with **HIV infection**, particularly those with low CD4+ counts [1]. - It is typically associated with the **Epstein-Barr virus (EBV)** and originates from B-lymphocytes [1]. *Astrocytoma* - While astrocytomas are common primary brain tumors in the general population, they are **not specifically linked to HIV infection** or seen with increased frequency in this patient group. - They arise from astrocytes and vary widely in their aggressiveness. *Glioma* - Gliomas are a broad category of tumors arising from glial cells; **astrocytomas** are a type of glioma. - Like astrocytomas, gliomas are not specifically augmented in incidence in HIV-infected individuals. *Medulloblastoma* - Medulloblastomas are primarily **pediatric tumors** occurring in the **cerebellum**. - There is no known association between medulloblastoma and HIV infection in adults or children.

Q: What is the most common viral illness transmitted via homologous blood transfusion?

Hepatitis B (HBV). **Hepatitis B (HBV)** - Although screening has significantly reduced the risk, **Hepatitis B (HBV)** remains a frequently transmitted viral infection through homologous blood transfusion due to its relatively **high viremia** and occassional **'window period'** infections that can evade detection [1]. - HBV also has a significant global prevalence, contributing to its ongoing presence as a risk despite rigorous testing protocols [1]. *Hepatitis C (HCV)* - While historically a leading cause of post-transfusion hepatitis, advanced **nucleic acid amplification testing (NAAT)** has dramatically reduced the risk of HCV transmission via blood products [1]. - The **prevalence of HCV** in the general population coupled with sensitive screening tests means it is now less commonly transmitted than HBV through transfusion [1]. *HIV* - The risk of **HIV transmission** through blood transfusion is exceedingly low in developed countries due to highly effective and sensitive screening methods, including **NAAT** and antibody tests [1]. - While devastating, the **incidence of transfusion-related HIV** is rare due to stringent donor selection and testing [1]. *Cytomegalovirus (CMV)* - **CMV** transmission through blood transfusion is a concern primarily in **immunocompromised recipients** (e.g., neonates, transplant patients) where it can cause significant morbidity. - For the general population, CMV infection from transfusion is often subclinical or mild, and leukoreduction of blood products has further reduced its transmission risk [1].

Question 1

All of the following are true about dengue fever except:

Accepted Answer

Thrombocytosis

Answer

Elevated hematocrit

Answer

Transmitted by Aedes

Answer

Also called as breakbone fever

Question 2

Female treated for Urinary tract infection now has vaginal discharge. The most likely organism is?

Accepted Answer

Candida

Answer

Trichomonas

Answer

Ureaplasma urealyticum

Answer

Chlamydia

Question 3

A 20-year-old woman presents with headache, fever, and neck stiffness. On examination, her blood pressure is 100/70 mm Hg, pulse 100/min, temperature 38.6, and the neck is stiff and painful to flex and extend. The ears, throat, and sinuses are normal, there are no focal neurologic signs, and the remaining examination is normal. There are no reported similar cases in the community. Which of the following is the most likely source of her infection?

Accepted Answer

nasopharynx

Answer

skin

Answer

oral ingestion

Answer

an infected heart valve

Question 4

A farmer presents with multiple dicharging sinuses in the leg not responding to antibiotics. Most likely diagnosis is -

Accepted Answer

Madurella

Answer

Nocardia

Answer

Actino-mycetoma

Answer

Sporothrix

Question 5

Meyers Kouwenaar syndrome is a synonym for ?

Accepted Answer

Occult filariasis

Answer

Larva migrans

Answer

Tropical pulmonary eosinophilia

Answer

Cutaneous allergic reactions to Ascariasis

Question 6

Acquired megacolon can be due to

Accepted Answer

Chagas disease

Answer

Typhoid

Answer

Leishmaniasis

Answer

Amoebiasis

Question 7

An otherwise healthy male presents with a creamy curd like white patch on the tongue. The probable diagnosis is

Accepted Answer

Candidiasis

Answer

Histoplasmosis

Answer

Aspergillosis

Answer

Lichen Planus

Question 8

A 22-year-old homeless person with a known drug abuse problem and multiple opportunistic infections has a positive PPD (purified protein) test. Which of the following is the most common way this infection is acquired?

Accepted Answer

Respiratory tract

Answer

GI tract

Answer

Genital tract

Answer

Nasal tract

Question 9

Which of the following is the most common CNS tumor associated with HIV infection?

Accepted Answer

Lymphoma

Answer

Astrocytoma

Answer

Glioma

Answer

Medulloblastoma

Question 10

What is the most common viral illness transmitted via homologous blood transfusion?

Accepted Answer

Hepatitis B (HBV)

Answer

Hepatitis C (HCV)

Answer

HIV

Answer

Cytomegalovirus (CMV)

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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