Parasitology

Parasitology Indian Medical PG Question 1: Cylindrical helminths are -

• A. Tapeworms
• B. Flukes
• C. Roundworms (Correct Answer)
• D. Hookworms

Parasitology Explanation: ***Roundworms*** - **Roundworms**, also known as **nematodes**, are characterized by their **cylindrical body shape**. - Their unsegmented, tapered bodies distinguish them from flatworms like tapeworms and flukes. *Tapeworms* - **Tapeworms**, or **cestodes**, have **flat, ribbon-like bodies** segmented into proglottids. - They are not cylindrical but rather dorsoventrally flattened. *Flukes* - **Flukes**, or **trematodes**, have **flat, leaf-shaped bodies**, which are not cylindrical. - Their morphology includes suckers for attachment and they are not segmented. *Hookworms* - **Hookworms** are a type of **roundworm** (nematode), which means they are cylindrical. However, "Roundworms" is a broader and more accurate classification for the general term "cylindrical helminths." - While hookworms are indeed cylindrical, the option "Roundworms" encompasses all such cylindrical helminths, making it a more general and appropriate answer.

Parasitology Indian Medical PG Question 2: Mass treatment strategy is for treating -

• A. Cholera
• B. Plague
• C. Filariasis (Correct Answer)
• D. Diphtheria

Parasitology Explanation: ***Filariasis*** - **Mass drug administration (MDA)** is a key strategy for the elimination of lymphatic filariasis globally, aiming to treat entire populations in affected areas. - This approach interrupts the transmission cycle by reducing the parasite load in infected individuals, even those without overt symptoms. *Cholera* - Management of cholera primarily involves **rehydration therapy** and, for severe cases, **antibiotics** administered to symptomatic individuals. - While rapid response is crucial, mass treatment of entire populations is not the standard approach for cholera control. *Plague* - Treatment for plague involves **antibiotics** given to individuals suspected or confirmed to have the infection, or for post-exposure prophylaxis in close contacts. - Mass treatment strategies are not typically employed for plague, as it usually presents as localized outbreaks rather than widespread endemic disease suitable for MDA. *Diphtheria* - Treatment for diphtheria focuses on **antitoxin administration** and **antibiotics** to neutralize toxins and eliminate bacteria in infected patients. - Prevention is primarily through **vaccination**, and mass treatment is not a strategy used for diphtheria control.

Parasitology Indian Medical PG Question 3: In areas with chloroquine-sensitive P. vivax, what is the preferred drug for treating the blood stages?

• A. Mefloquine
• B. Artesunate
• C. Quinine
• D. Chloroquine (Correct Answer)

Parasitology Explanation: ***Correct Option: Chloroquine***- **Chloroquine** remains the **first-line treatment** for **chloroquine-sensitive P. vivax** infections due to its high efficacy and safety profile [1, 2].- It rapidly clears **blood-stage parasites**, alleviating acute symptoms of malaria [3].- In areas where P. vivax remains sensitive, chloroquine is preferred due to low cost, good tolerability, and proven effectiveness [1, 2].*Incorrect Option: Mefloquine*- **Mefloquine** is typically reserved for areas with **chloroquine-resistant P. falciparum** or for prophylaxis in such regions.- Its use is generally avoided when less toxic and equally effective options like chloroquine are available for sensitive strains.- Associated with more neuropsychiatric side effects.*Incorrect Option: Artesunate*- **Artesunate** is an **artemisinin derivative**, primarily used for severe malaria or in areas with **multi-drug resistant P. falciparum**.- While effective, it is not the preferred first-line agent for chloroquine-sensitive P. vivax due to the availability of simpler, equally effective treatments.- Typically used in combination therapy (ACT) for resistant strains.*Incorrect Option: Quinine*- **Quinine** is an older antimalarial, often used for **severe malaria** or in cases of **chloroquine-resistant P. falciparum**.- It has a higher incidence of side effects compared to chloroquine (cinchonism, hypoglycemia) and is not the preferred choice for chloroquine-sensitive P. vivax.- Requires longer treatment duration with more monitoring.

Parasitology Indian Medical PG Question 4: Which one of the following statements is correct in the diagnosis of Giardiasis?

• A. String test is done to find out cysts of Giardia lamblia
• B. Jejunal biopsy samples can show presence of larvae of Giardia lamblia
• C. Cystic form of Giardia lamblia remains viable in water upto 1 week only
• D. Stool sample at 2-3 days interval should be examined for cysts (Correct Answer)

Parasitology Explanation: ***Stool sample at 2-3 days interval should be examined for cysts*** - Due to the **intermittent shedding** of *Giardia lamblia* cysts, multiple stool samples collected over several days (e.g., 2-3 days apart for a total of three samples) significantly increase the sensitivity of detection. - Microscopic examination of these samples for the presence of **cysts** is a primary diagnostic method for giardiasis. *String test is done to find out cysts of Giardia lamblia* - The **string test** (or Entero-Test) is primarily used to collect **trophozoites** from the duodenum, not cysts. - Cysts are typically found in **feces**, while trophozoites are free-living in the upper small intestine. *Jejunal biopsy samples can show presence of larvae of Giardia lamblia* - *Giardia lamblia* exists as **trophozoites** and **cysts**, not larvae. - While trophozoites can be seen in jejunal biopsies, they are **protozoan parasites**, not helminthic larvae. *Cystic form of Giardia lamblia remains viable in water upto 1 week only* - *Giardia lamblia* cysts are **highly resistant** and can remain viable in cold water for **months**, much longer than one week. - This extreme viability contributes to the widespread transmission of giardiasis through contaminated water sources.

Parasitology Indian Medical PG Question 5: Which of the following statements regarding giardiasis is false?

• A. Metronidazole is the drug of choice
• B. Absence of fever
• C. Diarrhea with steatorrhea
• D. Bloody diarrhea (Correct Answer)

Parasitology Explanation: Bloody diarrhea - **Giardiasis** is caused by the flagellate **_Giardia lamblia_**, which colonizes the small intestine and disrupts nutrient absorption, leading to **non-bloody diarrhea** [1]. - The parasite does not invade the intestinal wall, so **bloody stools are not a typical feature**; their presence suggests other infectious agents or conditions [1]. *Diarrhea with steatorrhea* - **_Giardia lamblia_ infection** impairs fat absorption in the small intestine, leading to the characteristic **fatty, foul-smelling stools known as steatorrhea**. - This malabsorption is due to damage to the brush border of enterocytes and disruption of bile salt metabolism. *Metronidazole is the drug of choice* - **Metronidazole** is indeed the **first-line treatment** for giardiasis, highly effective against the parasitic trophozoites. - Other effective alternatives include **tinidazole** and **nitazoxanide**, depending on regional resistance patterns and patient factors. *Absence of fever* - **Giardiasis** typically causes **gastrointestinal symptoms** such as diarrhea, abdominal cramps, and bloating, without systemic signs like fever [1]. - The absence of fever helps differentiate giardiasis from invasive infections that cause inflammatory responses.

Parasitology Flashcard 1 of 5

Question: What parasite class has all hermaphrodite members?_____

Answer: Cestodes and trematodes except Schistosoma

Parasitology Flashcard 2 of 5

Question: Plasmodium _____ has the shortest incubation period.

Answer: falciparum

Parasitology Flashcard 3 of 5

Question: The infective form of Strongyloides stercoralis is the _____ larva

Answer: filariform (rhabditiform/filariform)

Parasitology Flashcard 4 of 5

Question: What diagnostic tests are run to test for Giardia?_____

Answer: Stool O&P (ova and parasites)

Parasitology Flashcard 5 of 5

Question: What is the most common parasitic pathogen in humans?_____

Answer: Giardia lamblia