Block 10 Blood Tissu Protozo Filar Worms MCQ's

When a mosquito bites a victim and infects them with malaria, the sporozoite stage of the parasite enters the host. Sporozoites are the infective form of the malaria parasite that are injected into the bloodstream of the host when a mosquito bites. Once inside the host, the sporozoites travel to the liver where they multiply and develop into merozoites, which then infect the red blood cells and cause the symptoms of malaria.

The most probable diagnosis for the 35-year-old English businessman is malaria. This is indicated by the symptoms presented such as fever, abdominal pain, sweating, rigors, vomiting, jaundice, and altered mental status. The fact that he had been on vacation in India also increases the likelihood of malaria, as it is endemic in certain regions of India. The blood smear showing intraerythrocytic organisms further supports the diagnosis of malaria.

The most probable diagnosis in this case is babesiosis. The symptoms described, including persistent fever, abdominal pain, sweating, rigors, vomiting, jaundice, and febrile state, are consistent with babesiosis. Additionally, the fact that the patient recently returned from a vacation in Minnesota, where babesiosis is endemic, further supports this diagnosis. The presence of intraerythrocytic organisms with peculiar tetrad forms on the blood smear is also characteristic of babesiosis.

The concern about the efficacy of the vaccine arises because the sporozoite stage of Plasmodium falciparum, which the vaccine targets, quickly reaches the liver after being injected by the mosquito. Once in the liver, it is relatively protected from immune attack. Therefore, the vaccine may not be effective in preventing the infection from progressing to the liver stage, where it can cause harm.

The correct answer is sporozoite. Malaria is transmitted to humans through the bite of infected mosquitoes. When a mosquito bites an infected person, it ingests the sporozoites, which are the infective stage of the malaria parasite. These sporozoites then travel to the mosquito's salivary glands and are injected into a new person when the mosquito bites again. Therefore, a vaccine that can prevent disease in a person at risk of being bitten by an infected mosquito must protect against the sporozoite stage of the parasite's life cycle.

Biopsied muscle can be used to detect a helminth that is naturally transmitted by ingestion of pork, bear, or walrus meat. This is because when a person consumes infected meat, the helminth larvae can migrate and infect different tissues in the body, including muscle tissue. Therefore, by conducting a biopsy on the muscle, it is possible to identify the presence of the helminth and confirm the infection. Other options such as vaginal secretions, duodenal contents, blood, and sputum may not be suitable for detecting this particular helminth as they are not directly involved in the transmission or migration of the parasite.

The most probable immediate cause of death in this case is cerebral malaria. The patient presented with symptoms of malaria, including fever, jaundice, and heavy infestation with intraerythrocytic parasites. Cerebral malaria is a severe form of the disease that can lead to coma and death. The fact that the patient deteriorated rapidly and became comatose suggests that cerebral malaria was the cause of death.

The correct answer is Plasmodium falciparum. The patient's symptoms of paroxysmal attacks of chills, fever, and sweating, along with the presence of ringlike and crescent-like forms within red blood cells, are indicative of malaria. Plasmodium falciparum is the most common and deadliest species of malaria parasite, causing severe symptoms and potentially fatal complications.

Intestinal amebae can cause peritonitis and liver abscesses. This means that when these amebae infect the human body, they have the potential to cause inflammation of the lining of the abdominal cavity (peritonitis) and the formation of pus-filled pockets in the liver (liver abscesses). This suggests that the presence of these amebae can lead to serious health complications and should not be taken lightly.

A vaccine that is intended to specifically prevent the infection of human erythrocytes by the malaria parasite must be directed against the merozoite stage of the organism's life cycle. The merozoite is the stage of the parasite that invades red blood cells and causes the symptoms of malaria. By targeting the merozoites, the vaccine can prevent the parasite from entering and multiplying within the red blood cells, thus preventing the infection and the development of malaria symptoms.

A protozoan with characteristic jerky motility is most commonly observed in vaginal secretions. This suggests that the protozoan is likely a sexually transmitted infection or a common inhabitant of the vaginal microbiota. It is important to note that the specific protozoan species responsible for this observation is not mentioned in the question.

IgG facilitated killing by macrophages is a mechanism that involves the binding of IgG antibodies to the surface of the protozoa, which then triggers the macrophages to engulf and destroy the protozoa. This mechanism is effective for protozoa because they are unicellular organisms and can be easily engulfed by macrophages. On the other hand, helminthes are multicellular organisms and are too large to be engulfed by macrophages, so this killing mechanism would not be effective for them.

In the chronic stage of Trypanosoma cruzi infection, the main lesions are often observed in the heart and digestive tract. This is because Trypanosoma cruzi is known to cause Chagas disease, which primarily affects the heart and gastrointestinal system. The parasite can invade and multiply within the muscle cells of the heart, leading to cardiac complications such as arrhythmias and heart failure. It can also affect the smooth muscle cells of the digestive tract, causing problems with digestion and absorption of nutrients. Therefore, the presence of lesions in the heart and digestive tract is characteristic of Chagas disease caused by Trypanosoma cruzi infection.

The correct answer is "Motile trophozoites from the colon invaded the liver". This is because the symptoms described, such as dysentery and liver abscess, are characteristic of an infection caused by the parasite Entamoeba histolytica. This parasite exists in two forms, a motile trophozoite stage and a cyst stage. The motile trophozoites can invade the colon and then spread to other organs, including the liver, causing abscesses. The other answer choices, such as parasitic cysts or eggs, bacteria, and hepatitis virus, do not fit the clinical presentation described in the question.

The patient in the question is most likely infected with Toxoplasmosis. Chorioretinitis is a common manifestation of Toxoplasmosis infection, which is caused by the parasite Toxoplasma gondii. The Sabin-Feldman dye test is a specific serological test used to detect antibodies against Toxoplasma gondii. Eating raw hamburger can be a potential source of Toxoplasma infection, as the parasite can be present in undercooked or raw meat.