Echinococci and other tissue helminths US Medical PG Practice Questions and MCQs
Practice US Medical PG questions for Echinococci and other tissue helminths. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Echinococci and other tissue helminths US Medical PG Question 1: A 4-year-old girl presents with recurrent abdominal pain and a low-grade fever for the past 2 months. The patient’s mother says that she has lost her appetite which has caused some recent weight loss. She adds that the patient frequently plays outdoors with their pet dog. The patient is afebrile and vital signs are within normal limits. On physical examination, conjunctival pallor is present. Abdominal examination reveals a diffusely tender abdomen and significant hepatomegaly. There is also a solid mass palpable in the right upper quadrant measuring about 3 x 4 cm. Laboratory findings are significant for the following:
Hemoglobin (Hb%) 9.9 g/dL
Total count (WBC) 26,300/µL
Differential count
Neutrophils 36%
Lymphocytes 16%
Eosinophils 46%
Platelets 200,000/mm3
Erythrocyte sedimentation rate 56 mm/h
C-reactive protein 2 mg/L
Serum globulins 5 g/dL
Laparoscopic resection of the mass is performed, and a tissue sample is sent for histopathology. Which of the following is the organism most likely responsible for this patient’s condition?
- A. Ancylostoma braziliense
- B. Ascaris lumbricoides
- C. Toxocara canis (Correct Answer)
- D. Trichuris trichiura
- E. Toxocara cati
Echinococci and other tissue helminths Explanation: ***Toxocara canis***
- The child's history of playing outdoors with a pet dog, **eosinophilia**, **hepatomegaly**, abdominal mass, and **elevated globulins** are highly suggestive of **visceral larva migrans (VLM)**, most commonly caused by *Toxocara canis*.
- *Toxocara canis* larvae migrate through human tissues, particularly the liver, causing granuloma formation that can present as palpable masses and systemic symptoms.
*Ancylostoma braziliense*
- This hookworm primarily causes **cutaneous larva migrans**, presenting as an intensely pruritic, serpiginous rash.
- It does not typically cause systemic symptoms like hepatomegaly, abdominal masses, or significant eosinophilia in the way described.
*Ascaris lumbricoides*
- *Ascaris lumbricoides* causes **ascariasis**, primarily manifesting as intestinal symptoms, malnutrition, or pulmonary symptoms during larval migration (Löffler syndrome)
- While it can cause eosinophilia, it rarely presents with solid hepatic masses or the specific constellation of symptoms seen here.
*Trichuris trichiura*
- *Trichuris trichiura* causes **trichuriasis** (whipworm infection), primarily leading to **gastrointestinal symptoms** such as abdominal pain, diarrhea, and rectal prolapse in heavy infections.
- It is not associated with migratory visceral larvae, hepatomegaly, or palpable liver masses.
*Toxocara cati*
- While *Toxocara cati* also causes visceral larva migrans, it is associated with **cats** rather than dogs. The patient's history specifically mentions a pet dog.
- The clinical presentation with hepatomegaly, abdominal mass, and eosinophilia would otherwise be consistent with *Toxocara* infection.
Echinococci and other tissue helminths US Medical PG Question 2: A 53-year-old woman with hypertension is brought to the emergency department 30 minutes after having a generalized, tonic-clonic seizure. She has had recurrent headaches and dizziness in the last 3 months. One year ago, she had diarrhea after a trip to Ecuador that resolved without treatment. She has not received any medical care in the last five years. She has smoked 1 pack of cigarettes daily for 20 years. Her temperature is 36°C (96.8°F) and blood pressure is 159/77mm Hg. Physical examination shows dysarthria and hyperreflexia. She is confused and oriented only to name and place. Four brain lesions are found in a CT scan of the brain; one of the lesions is shown. Which of the following is most likely to have prevented this patient's condition?
- A. Smoking cessation
- B. Avoidance of cat feces
- C. Vaccination against meningococcus
- D. Avoidance of contaminated food (Correct Answer)
- E. Improved blood pressure control
Echinococci and other tissue helminths Explanation: ***Avoidance of contaminated food***
- The patient's presentation with **recurrent seizures**, **multiple brain lesions**, and a history of travel to **Ecuador** followed by diarrhea strongly suggests **neurocysticercosis**.
- **Neurocysticercosis** is caused by ingesting **Taenia solium** eggs, typically through **contaminated food or water** (fecal-oral transmission), leading to the formation of cysts in the central nervous system.
- **Prevention** is achieved by avoiding contaminated food/water and proper food hygiene, particularly in endemic areas like Latin America.
*Smoking cessation*
- While smoking cessation is crucial for overall health and reduces cancer risk, it is **not directly linked** to preventing parasitic infections or the development of neurocysticercosis.
- Smoking is associated with lung and cardiovascular diseases but not with this specific neurological parasitic infection.
*Avoidance of cat feces*
- Avoiding cat feces is primarily recommended to prevent **toxoplasmosis** (caused by *Toxoplasma gondii*), another parasitic infection that can cause brain lesions, especially in immunocompromised individuals.
- However, the history of **diarrhea after travel to Ecuador** is more indicative of **Taenia solium**, which is transmitted fecal-orally through contaminated food, not through cat feces.
*Vaccination against meningococcus*
- Meningococcal vaccination prevents bacterial meningitis caused by *Neisseria meningitidis*.
- This patient's symptoms and CT findings of **multiple, ring-enhancing cystic brain lesions** are not consistent with meningococcal disease, which typically presents as acute meningitis or sepsis, not chronic space-occupying lesions.
*Improved blood pressure control*
- Hypertension control is vital for preventing **stroke** and other cardiovascular complications, which can cause neurological symptoms.
- However, the presence of **multiple, well-defined cystic brain lesions** and the history of travel to an endemic area with subsequent diarrhea point towards an **infectious etiology** (neurocysticercosis) rather than hypertensive cerebrovascular disease, which would show different imaging patterns (hemorrhage or infarction).
Echinococci and other tissue helminths US Medical PG Question 3: A 7-year-old girl is brought to the physician by her mother because of a 4-week history of irritability, diarrhea, and a 2.2-kg (5-lb) weight loss that was preceded by a dry cough. The family returned from a vacation to Indonesia 2 months ago. Her vital signs are within normal limits. Abdominal examination shows mild tenderness with no guarding or rebound and increased bowel sounds. Her leukocyte count is 9,200/mm3 with 20% eosinophils. A photomicrograph of a wet stool mount is shown. Which of the following is the most appropriate pharmacotherapy?
- A. Diethylcarbamazine
- B. Metronidazole
- C. Albendazole (Correct Answer)
- D. Praziquantel
- E. Doxycycline
Echinococci and other tissue helminths Explanation: ***Albendazole***
- The image shows a **hookworm egg**, characterized by its thin shell and developing larva inside; clinical features like **eosinophilia**, diarrhea, weight loss, and travel to an endemic area (Indonesia) are consistent with hookworm infection.
- **Albendazole** is the drug of choice for treating hookworm infections and other intestinal nematode infections.
*Diethylcarbamazine*
- This drug is primarily used for treating **lymphatic filariasis** (e.g., Wuchereria bancrofti, Brugia malayi) and **Loiasis** (African eye worm).
- It is not effective against hookworm infections.
*Metronidazole*
- **Metronidazole** is an antimicrobial agent effective against certain parasitic infections like **Giardia**, **Entamoeba histolytica**, and bacterial vaginosis.
- It is not indicated for the treatment of hookworm infections.
*Praziquantel*
- **Praziquantel** is an anthelminthic drug primarily used to treat infections caused by **flukes** (e.g., Schistosoma species) and **tapeworms** (e.g., Taenia species).
- It is not effective against hookworm infections.
*Doxycycline*
- **Doxycycline** is a tetracycline antibiotic with broad-spectrum activity against various bacterial infections and is also used in the treatment of some parasitic infections like **malaria prophylaxis** and **filariasis** (due to activity against Wolbachia endosymbionts).
- It is not a primary treatment for hookworm infections.
Echinococci and other tissue helminths US Medical PG Question 4: A 42-year-old woman comes to the physician because of episodic abdominal pain and fullness for 1 month. She works as an assistant at an animal shelter and helps to feed and bathe the animals. Physical examination shows hepatomegaly. Abdominal ultrasound shows a 4-cm calcified cyst with several daughter cysts in the liver. She undergoes CT-guided percutaneous aspiration under general anesthesia. Several minutes into the procedure, one liver cyst spills, and the patient's oxygen saturation decreases from 95% to 64%. Her pulse is 136/min, and blood pressure is 86/58 mm Hg. Which of the following is the most likely causal organism of this patient's condition?
- A. Clonorchis sinensis
- B. Trichinella spiralis
- C. Echinococcus granulosus (Correct Answer)
- D. Strongyloides stercoralis
- E. Schistosoma mansoni
Echinococci and other tissue helminths Explanation: ***Echinococcus granulosus***
- The presentation of a **calcified liver cyst** with **daughter cysts** in a patient with animal exposure (**animal shelter worker**) is highly suggestive of **hydatid disease** caused by *Echinococcus granulosus*.
- The **anaphylactic-like reaction** (decreased oxygen saturation, hypotension, tachycardia) upon cyst spillage during aspiration is a classic and dangerous complication, indicating a severe allergic response to the **hydatid fluid**.
*Clonorchis sinensis*
- This parasite causes **cholangitis** and **cholangiocarcinoma**, and typically presents with symptoms related to biliary obstruction, rather than large calcified cysts with daughter cysts.
- It is acquired by eating **undercooked freshwater fish** and is endemic in East Asia, which doesn't align with the patient's exposure history or cyst morphology.
*Trichinella spiralis*
- This parasite is acquired by consuming **undercooked pork** and causes **trichinosis**, characterized by muscle pain, periorbital edema, and eosinophilia, and does not typically form liver cysts.
- Liver involvement with *Trichinella* is rare and does not manifest as calcified cysts with daughter cysts.
*Strongyloides stercoralis*
- This nematode causes **strongyloidiasis**, often manifesting as gastrointestinal symptoms, skin rash (**larva currens**), and pulmonary symptoms in cases of autoinfection.
- It does not form macroscopic liver cysts, and liver involvement is generally non-cystic.
*Schistosoma mansoni*
- Causes **schistosomiasis**, which can lead to **hepatic fibrosis** (**pipestem fibrosis**) and **portal hypertension**, but does not typically cause large, calcified hydatid-like cysts with daughter cysts.
- Infection is acquired through contact with **freshwater contaminated with snails** carrying the parasitic larvae.
Echinococci and other tissue helminths US Medical PG Question 5: A 45-year-old man comes to the physician because of a 5-day history of fever, malaise, and right upper abdominal pain. Examination of the abdomen shows tenderness in the right upper quadrant. His leukocyte count is 18,000/mm3 (90% neutrophils) and serum alkaline phosphatase is 130 U/L. Ultrasonography of the abdomen shows a 3-cm hypoechoic lesion in the right lobe of the liver with a hyperemic rim. Which of the following is the most likely underlying cause of this patient's condition?
- A. Diverticulitis
- B. Echinococcosis
- C. Pyogenic liver abscess
- D. Cholangitis (Correct Answer)
- E. Perinephric infection
Echinococci and other tissue helminths Explanation: The patient presents with a **pyogenic liver abscess** (fever, RUQ pain, leukocytosis, hypoechoic liver lesion with hyperemic rim). The question asks for the **underlying cause** of this abscess.
***Cholangitis***
- **Cholangitis** (ascending biliary infection) is the **most common underlying cause** of pyogenic liver abscesses, accounting for 40-60% of cases
- The elevated **alkaline phosphatase** (130 U/L) suggests **biliary tract pathology**, supporting cholangitis as the source
- Bacteria ascend from the biliary tree through the portal venous system to seed the liver parenchyma
- The **leukocytosis with neutrophilia** (18,000/mm³, 90% neutrophils) indicates acute bacterial infection
- **Clinical correlation**: Biliary obstruction from stones, strictures, or malignancy → cholangitis → hematogenous/direct spread → liver abscess
*Diverticulitis*
- **Diverticulitis** typically causes **left lower quadrant pain** and fever, not right upper quadrant symptoms
- While portal pylephlebitis from diverticulitis can rarely cause liver abscesses, the **elevated alkaline phosphatase** points more toward biliary pathology than colonic source
- Absence of GI symptoms (diarrhea, constipation, lower abdominal pain) makes this less likely
*Echinococcosis*
- **Echinococcosis** (hydatid cyst) presents with a **slow-growing, asymptomatic cyst** over months to years, not acute fever
- Imaging shows **multiloculated cysts with daughter cysts** and calcifications ("water lily sign"), not a hyperemic rim suggesting acute inflammation
- Would not cause marked leukocytosis unless the cyst ruptures
*Pyogenic liver abscess*
- This is the **condition the patient HAS**, not the underlying cause
- A pyogenic liver abscess is the result of bacterial seeding, which can occur from biliary sources (cholangitis), hematogenous spread, or direct extension
- The question asks for what **caused** the abscess, not what the abscess is
*Perinephric infection*
- **Perinephric abscess** causes **flank pain** and costovertebral angle tenderness, not RUQ pain
- Imaging would show perirenal or intrarenal findings, not an **isolated liver lesion**
- No urinary symptoms are mentioned
Echinococci and other tissue helminths US Medical PG Question 6: A 35-year-old man is brought to the emergency department after experiencing a seizure. According to his girlfriend, he has had fatigue for the last 3 days and became confused this morning, after which he started having uncontrollable convulsions throughout his entire body. He was unconscious throughout the episode, which lasted about 4 minutes. He has not visited a physician for over 10 years. He has smoked one pack of cigarettes daily for 12 years. His girlfriend admits they occasionally use heroin together with their friends. His temperature is 38.8°C (101.8°F), pulse is 93/min, respirations are 20/min, and blood pressure is 110/70 mm Hg. The lungs are clear to auscultation and examination shows normal heart sounds and no carotid or femoral bruits. He appears emaciated and somnolent. There are multiple track marks on both his arms. He is unable to cooperate for a neurological exam. Laboratory studies show a leukocyte count of 3,000/mm3, a hematocrit of 34%, a platelet count of 354,000/mm3, and an erythrocyte sedimentation rate of 27 mm/h. His CD4+ T-lymphocyte count is 84/mm3 (normal ≥ 500). A CT scan of the head is shown. Which of the following is the most appropriate next step considering this patient's CT scan findings?
- A. Pyrimethamine, sulfadiazine, and leucovorin (Correct Answer)
- B. Trimethoprim-sulfamethoxazole
- C. Albendazole
- D. Glucocorticoids
- E. CT-guided stereotactic aspiration
Echinococci and other tissue helminths Explanation: ***Pyrimethamine, sulfadiazine, and leucovorin***
- The patient presents with **immunosuppression** (CD4+ count of 84/mm³), neurological symptoms including a seizure, and CT findings showing **multiple ring-enhancing lesions**, characteristic of **cerebral toxoplasmosis**.
- The recommended treatment for toxoplasmosis in immunocompromised patients is a combination of **pyrimethamine**, **sulfadiazine**, and **leucovorin** to mitigate the hematological side effects of pyrimethamine.
*Trimethoprim-sulfamethoxazole*
- While trimethoprim-sulfamethoxazole (TMP-SMX) is used for toxoplasmosis **prophylaxis** in HIV patients, it is not the first-line treatment for active cerebral toxoplasmosis due to lower efficacy compared to pyrimethamine/sulfadiazine.
- TMP-SMX is the preferred regimen for *Pneumocystis jirovecii pneumonia (PCP)* prophylaxis, which differs from the presentation here.
*Albendazole*
- **Albendazole** is an antihelminthic drug primarily used to treat infections caused by various parasitic worms, such as **neurocysticercosis**.
- The CT findings are more consistent with toxoplasmosis than neurocysticercosis, which often presents with calcified lesions in chronic cases or cysts in various stages.
*Glucocorticoids*
- **Glucocorticoids** (e.g., dexamethasone) are often used in conjunction with antimicrobial therapy for cerebral toxoplasmosis to reduce **cerebral edema** and mass effect, especially if there is significant inflammation or herniation risk.
- However, glucocorticoids alone are not a definitive treatment as they do not address the underlying parasitic infection and can exacerbate immunosuppression.
*CT-guided stereotactic aspiration*
- **Biopsy (CT-guided stereotactic aspiration)** is typically reserved for cases where the diagnosis of cerebral toxoplasmosis is uncertain, or if there is no clinical or radiological improvement after 1–2 weeks of empiric antitoxoplasmal therapy.
- Given the classic presentation in an immunocompromised patient, empiric treatment is the initial appropriate step, rather than immediate biopsy, to avoid invasive procedures if unnecessary.
Echinococci and other tissue helminths US Medical PG Question 7: Nucleic acid amplification testing (NAAT) of first-void urine confirms infection with Chlamydia trachomatis. Treatment with the appropriate pharmacotherapy is started. Which of the following health maintenance recommendations is most appropriate at this time?
- A. Take medication with food
- B. Avoid sun exposure
- C. Avoid drinking alcohol
- D. Avoid sexual activity for the next month (Correct Answer)
- E. Schedule an ophthalmology consultation
Echinococci and other tissue helminths Explanation: ***Avoid sexual activity for the next month***
- **CDC guidelines** recommend abstinence from sexual activity until 7 days after treatment completion AND until all sexual partners have been treated and cured. The recommendation of "the next month" provides adequate time to ensure both conditions are met, as **partner notification**, testing, and treatment often takes several weeks.
- This is the **most important health maintenance recommendation** as preventing **reinfection** and further **transmission** is the primary public health concern, superseding medication-specific advice.
*Take medication with food*
- This recommendation is specific to certain antibiotics to reduce gastrointestinal upset or improve absorption, but it is not a universal health maintenance recommendation for all Chlamydia treatments (e.g., **azithromycin** can be taken with or without food; **doxycycline** should be taken with food to reduce GI upset, but not milk products).
- While relevant to **medication adherence**, it is not the most crucial health maintenance advice regarding preventing transmission or re-infection.
*Avoid sun exposure*
- This advice is primarily given for medications that cause **photosensitivity**, such as **doxycycline**, which is a common treatment for Chlamydia.
- However, it's not applicable to all Chlamydia treatments (e.g., **azithromycin**) and is not the most critical health recommendation in the context of preventing disease transmission.
*Avoid drinking alcohol*
- This is a general recommendation for many antibiotic treatments to prevent potential interactions or increased side effects, but it is not a specific contraindication for the primary antibiotics used for Chlamydia.
- **Metronidazole**, used for other STIs (e.g., trichomoniasis), has a strong interaction with alcohol. However, it's not the primary treatment for Chlamydia, making this recommendation less universally appropriate here.
*Schedule an ophthalmology consultation*
- While Chlamydia can cause **conjunctivitis** (ophthalmia neonatorum in newborns or adult inclusion conjunctivitis), it is not a typical complication requiring routine ophthalmology consultation unless specific **ocular symptoms** are present.
- This recommendation is not a standard health maintenance strategy for **uncomplicated Chlamydia infections**.
Echinococci and other tissue helminths US Medical PG Question 8: A 38-year-old man comes to the physician because of a 2-week history of abdominal pain and an itchy rash on his buttocks. He also has fever, nausea, and diarrhea with mucoid stools. One week ago, the patient returned from Indonesia, where he went for vacation. Physical examination shows erythematous, serpiginous lesions located in the perianal region and the posterior thighs. His leukocyte count is 9,000/mm3 with 25% eosinophils. Further evaluation is most likely to show which of the following findings?
- A. Rhabditiform larvae on stool microscopy (Correct Answer)
- B. Entamoeba histolytica antibodies on stool immunoassay
- C. Branching septate hyphae on KOH preparation
- D. Oocysts on acid-fast stool stain
- E. Giardia lamblia antibodies on stool immunoassay
Echinococci and other tissue helminths Explanation: ***Rhabditiform larvae on stool microscopy***
- The patient's symptoms, including **abdominal pain**, **diarrhea with mucoid stools**, **itchy rash (larva currens)**, and **eosinophilia** after traveling to Indonesia, are highly suggestive of **Strongyloidiasis**.
- **Rhabditiform larvae** are typically found in stool samples during the diagnostic phase of strongyloidiasis, as adult worms live in the small intestine and release these larvae.
*Entamoeba histolytica antibodies on stool immunoassay*
- While *Entamoeba histolytica* can cause **dysentery**, **abdominal pain**, and fever, it does not cause an **itchy migratory rash** or significant **eosinophilia**.
- Diagnosis typically involves detecting **trophozoites or cysts** in stool or specific **antigen detection**, not usually antibodies in stool.
*Branching septate hyphae on KOH preparation*
- **Branching, septate hyphae** are characteristic of **fungal infections**, such as dermatophytosis, which primarily affect the skin.
- This finding would not explain the systemic symptoms like **abdominal pain**, **diarrhea**, **fever**, and eosinophilia described in the patient.
*Oocysts on acid-fast stool stain*
- **Oocysts detected by acid-fast stain** are indicative of parasitic infections like **Cryptosporidiosis** or **Cyclosporiasis**, which cause **watery diarrhea** and abdominal cramps.
- These infections do not typically present with the **pruritic serpiginous rash** (larva currens) or the high level of **eosinophilia** seen in this patient.
*Giardia lamblia antibodies on stool immunoassay*
- *Giardia lamblia* causes **giardiasis**, characterized by **diarrhea**, **abdominal cramps**, **bloating**, and **malabsorption**.
- However, giardiasis typically does not cause **eosinophilia** or an **itchy migratory rash**, which are key features in this case.
Echinococci and other tissue helminths US Medical PG Question 9: A 22-year-old man comes to the physician because of abdominal pain, diarrhea, and weight loss that started after a recent backpacking trip in Southeast Asia. He does not smoke or drink alcohol. His leukocyte count is 7,500/mm3 (61% segmented neutrophils, 13% eosinophils, and 26% lymphocytes). Stool microscopy shows rhabditiform larvae. This patient is most likely to develop which of the following?
- A. Perianal serpiginous rash (Correct Answer)
- B. Hematuria
- C. Rectal prolapse
- D. Peripheral lymphedema
- E. Muscle tenderness
Echinococci and other tissue helminths Explanation: ***Perianal serpiginous rash***
- The patient's symptoms (abdominal pain, diarrhea, weight loss, recent travel to Southeast Asia, eosinophilia, and rhabditiform larvae in stool) are highly suggestive of **Strongyloidiasis**.
- The **rhabditiform larvae** of **Strongyloides stercoralis** can autoinfect the host, migrating through the skin from the perianal area, causing a characteristic **larva currens** or **perianal serpiginous rash**.
*Hematuria*
- **Hematuria** is typically associated with **Schistosomiasis** (especially *Schistosoma haematobium*), which involves the genitourinary tract.
- While schistosomiasis is prevalent in some parts of Southeast Asia, the patient's presentation with **rhabditiform larvae** and **eosinophilia** points away from it.
*Rectal prolapse*
- **Rectal prolapse** can occur with chronic straining due to severe diarrhea or constipation, or in conditions like **Trichuriasis (whipworm infection)**.
- While diarrhea is present, the specific finding of **rhabditiform larvae** and the high eosinophil count are not characteristic of conditions directly leading to rectal prolapse.
*Peripheral lymphedema*
- **Peripheral lymphedema** is a hallmark symptom of **Filariasis**, caused by parasitic worms like *Wuchereria bancrofti* or *Brugia malayi*, transmitted by mosquitoes.
- The patient's presentation, particularly the **rhabditiform larvae in stool**, does not support a diagnosis of filariasis.
*Muscle tenderness*
- **Muscle tenderness** and myalgia can be associated with several parasitic infections, most notably **Trichinellosis**, caused by *Trichinella spiralis*.
- However, the finding of **rhabditiform larvae in stool** and the absence of specific symptoms like periorbital edema or splinter hemorrhages make trichinellosis less likely than strongyloidiasis.
Echinococci and other tissue helminths US Medical PG Question 10: A 45-year-old man with a history of poorly controlled human immunodeficiency virus (HIV) infection presents to the emergency room complaining of clumsiness and weakness. He reports a 3-month history of worsening balance, asymmetric muscle weakness, and speech difficulties. He recently returned from a trip to Guatemala to visit his family. He has been poorly compliant with his anti-retroviral therapy and his most recent CD4 count was 195. His history is also notable for rheumatoid arthritis and hepatitis C. His temperature is 99°F (37.2°C), blood pressure is 140/90 mmHg, pulse is 95/min, and respirations are 18/min. On exam, he has 4/5 strength in his right upper extremity, 5/5 strength in his left upper extremity, 5/5 strength in his right lower extremity, and 3/5 strength in his left lower extremity. His speech is disjointed with intermittent long pauses between words. Vision is 20/100 in the left eye and 20/40 in his right eye; previously, his eyesight was 20/30 bilaterally. This patient most likely has a condition caused by which of the following types of pathogens?
- A. Arenavirus
- B. Bunyavirus
- C. Herpesvirus
- D. Polyomavirus (Correct Answer)
- E. Picornavirus
Echinococci and other tissue helminths Explanation: ***Polyomavirus***
- The patient's **poorly controlled HIV**, **low CD4 count (195)**, and progressive neurological symptoms (clumsiness, weakness, speech difficulties, vision changes) are highly suggestive of **Progressive Multifocal Leukoencephalopathy (PML)**.
- PML is caused by the **JC virus**, which is a type of **polyomavirus**, typically reactivating in immunocompromised individuals.
*Arenavirus*
- Arenaviruses (e.g., Lassa fever virus) are known to cause **hemorrhagic fevers** and can lead to neurological complications, but the clinical presentation described (progressive focal neurological deficits in an HIV patient) is not typical for an arenavirus infection.
- While some arenaviruses cause **meningoencephalitis**, the progressive, demyelinating-like course seen in this patient points away from arenavirus.
*Bunyavirus*
- Bunyaviruses (e.g., Hantavirus, La Crosse encephalitis virus) can cause **encephalitis**, fever, and myalgia, but they don't typically present with the specific constellation of **progressive white matter lesions** and focal neurological signs characteristic of PML in an HIV patient.
- Hantaviruses are more associated with **hemorrhagic fever with renal syndrome** or **hantavirus cardiopulmonary syndrome**.
*Herpesvirus*
- While herpesviruses (e.g., HSV, CMV, VZV) can cause severe neurological disease in HIV patients (e.g., **CMV encephalitis**, **HSV encephalitis**, **VZV vasculopathy**), the described progressive multifocal deficits, especially with rapid worsening, in an HIV patient with a low CD4 count strongly favor PML.
- Herpesviral encephalitides often present with more acute onset, fever, and seizures, or specific radiographic patterns not directly matching PML.
*Picornavirus*
- Picornaviruses, such as enteroviruses, can cause **aseptic meningitis** or **encephalitis**, particularly in immunocompromised individuals.
- However, the progressive, multifocal neurological deficits, particularly affecting **white matter**, are not characteristic of picornavirus infections, which tend to cause more diffuse or acute inflammatory processes.
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