Parasitology Feb 2011 Part 2

Explanation
D. latum has a relatively complex life cycle that requires two intermediate hosts. This means that in order for D. latum to complete its life cycle, it needs to go through two different species of hosts. These intermediate hosts play a crucial role in the development and transmission of the parasite. Without both of these hosts, the life cycle of D. latum cannot be completed successfully.

Explanation
The pleurocercoid is a larval stage of the tapeworm D. latum. When humans consume contaminated freshwater fish that is either raw or undercooked, they can ingest the pleurocercoid larvae, leading to an infection of D. latum.

Explanation
The correct answer is copepod. Copepods are a type of small crustacean that serve as the first intermediate host for the parasite Diphyllobothrium latum. These parasites require two intermediate hosts to complete their life cycle, with copepods being the first host. The larvae of D. latum are ingested by copepods, where they develop further before being transmitted to the second intermediate host, typically a fish. Therefore, the presence of copepods is crucial for the survival and transmission of D. latum.

Explanation
In the second stage involving D. Latum, the procercoid occurs in the copepod. This means that the parasite develops into the procercoid stage while inside the copepod. The infected copepod is then ingested by the second intermediate host, which is a freshwater fish.

Explanation
When an adult D. latum worm takes up residence in and attaches itself to the proximal part of the jejunum, the patient is at risk for developing vitamin B12 deficiency; this condition mimics that of pernicious anemia. The jejunum is the middle part of the small intestine, where most of the absorption of nutrients, including vitamin B12, occurs. When the worm attaches itself to the jejunum, it can interfere with the absorption of vitamin B12, leading to a deficiency. This deficiency can cause symptoms similar to pernicious anemia, which is characterized by a lack of intrinsic factor needed for vitamin B12 absorption.

Explanation
Residents of Finland appear to be at a higher risk for contracting Diphyllobothrium latum. This is because Diphyllobothrium latum, also known as the fish tapeworm, is commonly found in freshwater fish. Finland is known for its abundance of lakes and rivers, which provide a suitable habitat for the fish that carry this parasite. Therefore, people who consume raw or undercooked fish from these freshwater sources in Finland may be more susceptible to contracting Diphyllobothrium latum.

Explanation
Diphylidium caninum is known as the dog/cat tapeworm.

Explanation
Humans can become accidentally infected with Diphylidium Caninum by ingesting the intermediate hosts, which are fleas. Fleas are known to carry the Diphylidium Caninum tapeworm, and when a person accidentally ingests an infected flea, they can become infected with the tapeworm as well. The correct answer is "fleas" because it refers to the plural form of the intermediate hosts, emphasizing that multiple fleas can transmit the infection. The singular form "flea" is also correct, but it does not convey the same idea of multiple hosts.

Explanation
The incidence of Diphylidium caninum is worldwide, and children and kids are the primary persons at risk. This is because children and kids are more likely to come into close contact with infected animals, such as dogs and cats, who can transmit the parasite. Additionally, children and kids may have poorer hygiene practices, making them more susceptible to ingesting the infected fleas that carry the parasite. Therefore, it is important to educate and protect children and kids from potential exposure to Diphylidium caninum.

Explanation
The correct answer is "egg, eggs" because the diagnosis of D. caninum is determined by the presence of the characteristic egg packet or gravid proglottids in stool samples. These eggs or egg packets are specific to D. caninum and can be identified through microscopic examination. The plural form "eggs" is also included in the answer because multiple eggs or egg packets may be present in the stool sample, further confirming the diagnosis.

Explanation
The average diameter of a D. caninum egg can range from 30 to 60 um.

Explanation
The average D. caninum egg consists of the typical six hooked onchosphere.

Explanation
The eggs of D. caninum differ from those of other cestodes in that they are grouped together in membrane-enclosed packets. These packets can contain anywhere from 5 to 30 eggs.

Explanation
The given answer is "7, seven" because it accurately describes the number of suckers on the D. caninum scolex and the number of spines on the rostellum. The statement mentions that the scolex has four suckers, and the word "seven" completes the sentence by indicating that there is one circlet of spines on the rostellum.

Explanation
Mature and gravid proglottids of D. caninum resemble pumpkin seeds in shape. This means that they are small, flat, and oval-shaped, similar to the seeds found inside a pumpkin. The comparison helps to give a visual understanding of the shape and size of the proglottids, making it easier to identify and differentiate them from other structures.

Explanation
Each mature segment of D. caninum contains both male and female reproductive organs. After self-fertilization, the resulting gravid proglottid is full of eggs. These eggs are enclosed in an embryonic membrane.

Explanation
Echinococcus Granulosus is primarily found in areas where sheep are raised and where such animals are in close contact with dogs or wild canines. This is because sheep are the primary intermediate hosts for Echinococcus Granulosus, meaning they harbor the parasite in their organs. Dogs or wild canines become infected by consuming the organs of infected sheep, and then they can pass the parasite on to humans through their feces. Therefore, areas with a high population of sheep and close interaction with dogs or wild canines provide an ideal environment for the transmission of Echinococcus Granulosus.

Explanation
Echinococcus granulosus is a parasitic tapeworm that primarily infects dogs. It is also commonly referred to as the dog tapeworm or hydatid tapeworm. This tapeworm has a complex lifecycle, with dogs serving as the definitive host, meaning they harbor the adult tapeworm in their intestines. The tapeworm eggs are then shed in the dog's feces and can contaminate the environment, posing a risk to other animals and humans. Therefore, the correct answer is dog.

Explanation
The term "dead-end" refers to a host in which the life cycle of a parasite cannot continue. In the case of the Echinococcus parasite, the life cycle stops in human tissue, making humans dead-end hosts.

Explanation
When the sheep serves as the intermediate host for Echinococcus Granulosus, it allows the completion of the parasite's life cycle. This means that the parasite can develop and reproduce within the sheep, leading to the formation of cysts in its organs. These cysts contain the eggs of the parasite, which can be released into the environment through the sheep's feces. Other animals, including humans, can then become infected by ingesting these eggs, continuing the life cycle of Echinococcus Granulosus.

Explanation
Humans serve as an accidental intermediate host for Echinococcus Granulosus. This means that humans are not the natural or intended host for this parasite, but they can become infected by accidentally ingesting the eggs of the parasite, typically through contact with contaminated soil, water, or food. Once inside the human body, the parasite can develop into cysts in various organs, such as the liver or lungs, causing a condition known as hydatid disease.

Explanation
In Echinococcus Granulosis, the ingested eggs have the ability to migrate to different tissue sites, such as the lung and liver. In these infected tissues, a hydatid cyst develops.

Explanation
The correct answer is "Taenia, Taenias." The statement is suggesting that the eggs of E. granulosus are identical to and indistinguishable from the eggs of the Taenia species. This implies that the eggs of both E. granulosus and Taenia have similar characteristics and cannot be differentiated from each other.

Explanation
The diagnostic stage of Echinococcus Granulosis is the larval stage, not the egg stage. This means that in order to diagnose the infection, medical professionals look for the presence of the larval form of the parasite rather than the eggs. This is because the larval stage is the more advanced and infectious stage of the parasite's life cycle. By identifying the larval stage, healthcare providers can accurately diagnose and treat the infection.

Explanation
Within the hydatid cyst, miniaturizations of the entire hydatid cyst may occur and are called daughter cysts. These daughter cysts are smaller versions of the original cyst and can be found within the main cyst.

Explanation
Hydatid cysts of Echinococcus Granulosis may start out developing additional structures, but because of the onset of secondary bacterial infection are unable to continue thriving and result in sterility.