Tropical and Parasitic Infections — MCQs
True regarding malaria is:
A person presents to the hospital with fever and chills. Fever profile is ordered and is found to be negative for malaria and dengue. Rk39 test is found to be positive. What is the treatment of choice?
A female patient having frothy vaginal discharge was found to have a strawberry cervix. Which of the following is the drug of choice?
Tropical diseases targeted for research and training by WHO include all except:
What is the treatment for Trichomonas vaginalis?
Cysticercus cellulosae are pathogenic forms of which parasite?
Which of the following drugs has gametocidal action against all species of Plasmodium?
Which of the following conditions is NOT typically associated with eosinophilic meningitis?
In HIV patients, Kaposi's sarcoma is most likely caused by which of the following?
A 25-year-old man with 3 weeks of fever presented with tricuspid valve vegetation. The patient is an intravenous drug abuser. The most common cause of endocarditis in this patient is:
Tropical and Parasitic Infections Indian Medical PG Practice Questions and MCQs
Question 1: True regarding malaria is:
- A. Schizonts are infective to mosquitoes
- B. Trophozoites are infective to mosquitoes
- C. Persistent tissue phase seen in P. falciparum
- D. Persistent tissue phase seen in P. vivax (Correct Answer)
Explanation: ***Persistent tissue phase seen in P. vivax*** - The **persistent tissue phase** (or **exoerythrocytic phase**) is unique to *Plasmodium vivax* and *P. ovale*, where parasites infect **liver cells** (hepatocytes) and form **hypnozoites**. - **Hypnozoites** are **dormant forms** that can remain in the liver for weeks to months and cause **relapses** after the initial infection. - While all *Plasmodium* species have an initial liver phase, only *P. vivax* and *P. ovale* have this **persistent/dormant** tissue phase. *Schizonts are infective to mosquitoes* - **Schizonts** are a developmental stage found inside **human red blood cells** or **liver cells** during asexual reproduction. They are not infective to mosquitoes. - The stages infective to mosquitoes are the **gametocytes**, which are taken up by the female *Anopheles* mosquito during a blood meal. *Trophozoites are infective to mosquitoes* - **Trophozoites** are the feeding stage of the parasite within **human red blood cells** and consume hemoglobin. They are not infective to mosquitoes. - Only **gametocytes** (sexual forms) can continue the life cycle within the mosquito vector. *Persistent tissue phase seen in P. falciparum* - While *Plasmodium falciparum* does have an initial **exoerythrocytic (liver) phase**, it does **not** form **hypnozoites**. - Therefore, *P. falciparum* does **not** have a **persistent/dormant** liver stage and does not cause true relapses, unlike *P. vivax* and *P. ovale*.
Question 2: A person presents to the hospital with fever and chills. Fever profile is ordered and is found to be negative for malaria and dengue. Rk39 test is found to be positive. What is the treatment of choice?
- A. Amphotericin B (Correct Answer)
- B. Dapsone
- C. Hydroxychloroquine
- D. Griseofulvin
Explanation: Amphotericin B - A positive RK39 test suggests visceral leishmaniasis (kala-azar), especially with fever and chills in an endemic area [1]. - Amphotericin B (specifically liposomal Amphotericin B) is a highly effective and often the drug of choice for treating visceral leishmaniasis, particularly in severe cases or regions with antimonial resistance. Dapsone - Dapsone is primarily used in the treatment of leprosy and بعض forms of dermatitis (e.g., dermatitis herpetiformis). - It has no significant role in treating leishmaniasis. Hydroxychloroquine - Hydroxychloroquine is an antimalarial drug also used for certain autoimmune diseases like lupus and rheumatoid arthritis [2]. - It is ineffective against leishmaniasis. Griseofulvin - Griseofulvin is an antifungal medication used to treat dermatophyte infections (e.g., ringworm of the skin, hair, or nails). - It has no activity against Leishmania parasites.
Question 3: A female patient having frothy vaginal discharge was found to have a strawberry cervix. Which of the following is the drug of choice?
- A. Cefixime
- B. Tetracycline
- C. Metronidazole (Correct Answer)
- D. Fluconazole
Explanation: ***Correct Option: Metronidazole*** - The combination of **frothy vaginal discharge** and a **strawberry cervix** (colpitis macularis) is highly indicative of **trichomoniasis**, caused by *Trichomonas vaginalis*. - **Metronidazole** is the drug of choice for treating trichomoniasis, effectively eradicating the protozoan parasite. - Alternative: **Tinidazole** is also highly effective for trichomoniasis treatment. *Incorrect Option: Cefixime* - **Cefixime** is a third-generation cephalosporin antibiotic primarily used to treat bacterial infections, particularly **gonorrhea** (*Neisseria gonorrhoeae*). - It is not effective against parasitic infections like **trichomoniasis**. *Incorrect Option: Tetracycline* - **Tetracycline** is a broad-spectrum antibiotic commonly used for bacterial infections like **chlamydia** and certain atypical organisms. - It is not indicated for the treatment of **trichomoniasis**, which requires antiprotozoal therapy. *Incorrect Option: Fluconazole* - **Fluconazole** is an antifungal medication specifically used to treat **yeast infections** (vulvovaginal candidiasis caused by *Candida* species). - It has no activity against the protozoan parasite *Trichomonas vaginalis*.
Question 4: Tropical diseases targeted for research and training by WHO include all except:
- A. Schistosomiasis
- B. Rabies (Correct Answer)
- C. Trypanosomiasis
- D. Filariasis
Explanation: ***Rabies*** - While rabies is a significant public health concern, it is generally *not included* in the list of **Neglected Tropical Diseases (NTDs)** targeted for research and training by the WHO. - Rabies is often managed through **vaccination campaigns** and **post-exposure prophylaxis**, differing from many NTD control strategies focused on vector control and mass drug administration. *Schistosomiasis* - **Schistosomiasis** is a **parasitic disease** caused by trematode worms, and it is explicitly listed as one of the major **Neglected Tropical Diseases** targeted by the WHO. - The WHO focuses on controlling schistosomiasis through **preventive chemotherapy** and **improved sanitation**. *Trypanosomiasis* - **Trypanosomiasis**, specifically **African trypanosomiasis (sleeping sickness)** and **American trypanosomiasis (Chagas disease)**, are both prominent in the WHO's list of **NTDs**. - Research and training efforts are concentrated on disease surveillance, vector control, and access to diagnostics and treatment for these severe parasitic infections. *Filariasis* - **Filariasis**, including **lymphatic filariasis** and **onchocerciasis (river blindness)**, is another key **Neglected Tropical Disease** targeted by the WHO for elimination. - The WHO supports **mass drug administration** programs and vector control strategies to combat filariasis globally.
Question 5: What is the treatment for Trichomonas vaginalis?
- A. Metronidazole (Correct Answer)
- B. Azithromycin
- C. Ciprofloxacin
- D. None of the options
Explanation: ***Metronidazole*** - **Metronidazole** is the **first-line drug** for treating *Trichomonas vaginalis* infection. - It is effective against this **anaerobic protozoan** and can be administered as a single dose or a 7-day course. *Azithromycin* - **Azithromycin** is a **macrolide antibiotic** primarily used to treat bacterial infections, such as **chlamydia** or certain **respiratory tract infections**. - It is **not effective** against *Trichomonas vaginalis*, which is a parasitic protozoan. *Ciprofloxacin* - **Ciprofloxacin** is a **fluoroquinolone antibiotic** used for bacterial infections, especially **urinary tract infections** and complicated **gastrointestinal infections**. - It has **no activity** against *Trichomonas vaginalis*. *None of the options* - This option is incorrect because **Metronidazole** is a highly effective and widely accepted treatment for *Trichomonas vaginalis* infections.
Question 6: Cysticercus cellulosae are pathogenic forms of which parasite?
- A. Taenia solium (Correct Answer)
- B. Paragonimus westermani
- C. Enterobius vermicularis
- D. Taenia saginata
Explanation: ***Taenia solium*** - **Cysticercus cellulosae** is the larval stage (metacestode form) of the **pork tapeworm**, *Taenia solium*. - Humans can acquire **cysticercosis** by ingesting *T. solium* eggs, leading to the development of these cysticerci in various tissues, including the muscles, subcutaneous tissue, and central nervous system. *Paragonimus westermani* - This is a **lung fluke**; its larval stage is a metacercaria, not a cysticercus. - It causes **paragonimiasis**, characterized by lung symptoms. *Enterobius vermicularis* - This is the **pinworm**, a nematode, which does not have a cysticercus stage. - It primarily causes **perianal itching** and does not form cysts in tissues. *Taenia saginata* - This is the **beef tapeworm**, and its larval stage is known as a **Cysticercus bovis**, not Cysticercus cellulosae. - Humans acquire *T. saginata* infection by consuming undercooked beef containing C. bovis.
Question 7: Which of the following drugs has gametocidal action against all species of Plasmodium?
- A. Primaquine (Correct Answer)
- B. Quinine
- C. Chloroquine
- D. None of the options
Explanation: ***Primaquine*** - **Primaquine** is a **8-aminoquinoline** that is effective against the **gametocytes** of all *Plasmodium* species, including *P. falciparum*. - Its gametocidal action is crucial for **blocking transmission** of malaria, as gametocytes are the parasite forms ingested by mosquitoes. *Quinine* - **Quinine** is a **blood schizonticide** primarily used for treating acute, uncomplicated malaria, especially due to **chloroquine-resistant *P. falciparum***. - While it has some activity against *P. vivax* and *P. malariae* gametocytes, its action against mature *P. falciparum* gametocytes is limited. *Chloroquine* - **Chloroquine** is a highly effective **blood schizonticide** for **sensitive *P. falciparum***, *P. vivax*, *P. ovale*, and *P. malariae*. - It rapidly clears asexual parasites but has no effect on **mature *P. falciparum* gametocytes** and therefore does not prevent transmission of this species. *None of the options* - This option is incorrect because **Primaquine** possesses the described broad-spectrum gametocidal activity.
Question 8: Which of the following conditions is NOT typically associated with eosinophilic meningitis?
- A. Leptomeningeal metastasis (Correct Answer)
- B. Cryptococcal meningitis
- C. Coccidiomycosis
- D. Helminthic infections
Explanation: ***Leptomeningeal metastasis*** - This condition involves the spread of **malignant cells** to the leptomeninges, causing inflammation and neurological symptoms. - While it can cause inflammatory changes in the cerebrospinal fluid, it typically does not lead to a prominent **eosinophilic pleocytosis**. *Coccidiomycosis* - **Coccidioides immitis**, a dimorphic fungus, can cause **meningitis** and is a known cause of **eosinophilic meningitis**, particularly in endemic areas. - The fungal infection triggers a robust immune response that often involves an **eosinophil accumulation** in the CSF. *Cryptococcal meningitis* - Caused by **Cryptococcus neoformans** or **Cryptococcus gattii**, this fungal infection usually presents with **lymphocytic pleocytosis** or can have a normal cell count initially, especially in immunocompromised individuals. - Although it is a fungal infection, **eosinophilia** in the CSF is not a characteristic finding and is quite rare. *Helminthic infections* - Parasitic infections such as those caused by **Angiostrongylus cantonensis** (rat lungworm), **Gnathostoma spinigerum**, or **Taenia solium** (cysticercosis) are common causes of eosinophilic meningitis. - The immune response to the presence of these **helminths** in the central nervous system often involves a significant influx of eosinophils into the CSF.
Question 9: In HIV patients, Kaposi's sarcoma is most likely caused by which of the following?
- A. Bacteria
- B. Parasite
- C. Fungus
- D. Virus (Correct Answer)
Explanation: ***Virus*** - The image likely depicts **Kaposi's sarcoma**, a common lesion in HIV patients, which is caused by **Human Herpesvirus 8 (HHV-8)**. - Other viral infections like **Herpes Simplex Virus (HSV)** can also cause mucocutaneous lesions in immunocompromised individuals. *Bacteria* - While HIV patients are susceptible to bacterial infections (e.g., **Staphylococcus aureus** causing skin abscesses), the described lesion type is not characteristic of common bacterial skin infections. - Bacterial lesions often present as pustules, cellulitis, or ulcers with purulent discharge, which differ from typical Kaposi's sarcoma. *Parasite* - Parasitic infections can occur in HIV patients (e.g., **scabies** or **leishmaniasis**), but these typically present with different dermatological features like intensely itchy papules or nodular ulcerative lesions. - Lesions caused by parasites do not usually manifest as the violaceous, nodular, or plaque-like appearances seen in Kaposi's sarcoma. *Fungus* - Fungal infections in HIV patients can cause skin lesions (e.g., **candidiasis** with oral thrush or esophagitis, or **cryptococcosis** with molluscum-like lesions). - However, the morphology of these fungal lesions generally differs from the classic appearance of Kaposi's sarcoma or other common viral lesions in HIV.
Question 10: A 25-year-old man with 3 weeks of fever presented with tricuspid valve vegetation. The patient is an intravenous drug abuser. The most common cause of endocarditis in this patient is:
- A. Strep. viridans
- B. Pseudomonas
- C. Candida albicans
- D. Staph. aureus (Correct Answer)
Explanation: ***Staph. aureus*** - **Intravenous drug abuse (IVDA)** is a major risk factor for infective endocarditis, and *Staphylococcus aureus* is the most common causative organism, [1] particularly affecting the **tricuspid valve** on the right side of the heart. [2] - *S. aureus* can colonize the skin and needles used in IVDA, directly introducing bacteria into the bloodstream and to the heart valves. [1][3] *Strep. viridans* - *Streptococcus viridans* (viridans streptococci) is a common cause of native valve endocarditis, often following **dental procedures** or due to poor dental hygiene. [1] - It typically affects the **left-sided heart valves** (mitral or aortic) rather than the tricuspid valve, and is less commonly associated with IVDA. *Pseudomonas* - *Pseudomonas aeruginosa* can cause endocarditis, especially in IVDA patients or those with prosthetic valves, but it is **less common** than *Staphylococcus aureus* in this population. - While possible, it's not the *most common* cause specified in the question. *Candida albicans* - *Candida albicans* endocarditis is largely associated with **immunocompromised patients**, those with prosthetic valves, or prolonged use of broad-spectrum antibiotics, [4] not typically healthy IV drug abusers. - Fungal endocarditis is generally **rare** compared to bacterial endocarditis.
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