Question 1

Most individuals with histoplasmosis exhibit a hypersensitive state that can be demonstrated by the histoplasmin skin test.

Accepted Answer

Histoplasmin skin test is used to detect a previous exposure to Histoplasma capsulatum, the fungus that causes histoplasmosis. A positive test indicates a hypersensitive state, suggesting a previous exposure, but does not confirm the active infection.

Question 2

In the malarial life cycle,the male gamete is called _________.

Accepted Answer

In the malarial life cycle, the male gamete is called a microgametocyte. A macrogametocyte is the female gamete, while an oocyst is a structure that forms after fertilization of the gametes. An ookinete is a motile zygote that forms after fertilization and eventually becomes an oocyst.

Question 3

Dried pigeon droppings are a potential source of infection with ________.

Accepted Answer

Cryptococcus neoformans is a type of yeast that is commonly found in dried pigeon droppings and is known to cause disease in humans through inhalation of spores. The other choices listed are not commonly associated with pigeon droppings.

Question 4

Some superficial mycoses are called _________.

Accepted Answer

Tineas are superficial mycoses that affect keratinized tissue such as skin, hair, and nails. They are commonly known as "ringworm" infections. Sporotrichosis, dermatophytoses, and mycetomas are other types of fungal infections but are not classified specifically as superficial mycoses.

Question 5

Diagnosis of the leishmaniasis is based on finding the parasite within infected _________.

Accepted Answer

The parasite responsible for causing leishmaniasis (Leishmania species) resides inside macrophages within infected individuals. Therefore, the diagnosis of leishmaniasis is typically based on finding these parasites within macrophages, which can be done through methods such as microscopic examination or culture. Lymphocytes, eosinophils, and mast cells are not typically involved in the pathogenesis or diagnosis of leishmaniasis.

Question 6

Which of the following is not true with respect to the organism causing histoplasmosis?

Accepted Answer

The mold form of the organism causing histoplasmosis is not found in humans. It exists in the soil in the form of hyphae, which produce microconidia and macroconidia that can be inhaled and cause infection. Once in the lungs, the fungus grows intracellularly as a facultative parasite. Histoplasmosis is found worldwide, particularly in areas with high concentrations of bird or bat droppings, which serve as a reservoir for the fungus.

Question 7

Humans become infected with the malarial parasite when mosquitoes inject __________ into the bloodstream.

Accepted Answer

Malaria is caused by the Plasmodium parasite. When an infected female Anopheles mosquito bites a human, it injects sporozoites (which are in the mosquito's saliva) into the bloodstream. Sporozoites travel to the liver and invade liver cells, where they multiply and mature into merozoites. Merozoites are then released into the bloodstream to invade red blood cells, where they multiply and cause symptoms of malaria.

Question 8

All species of Leishmania utilize sand flies as intermediate hosts.

Accepted Answer

All species of Leishmania require sand flies as intermediate hosts in their life cycle. The parasites are transmitted to humans and other mammals when infected sand flies feed on their blood.

Question 9

Leishmania donovani causes

Accepted Answer

Leishmania donovani is the cause of visceral leishmaniasis, which is also known as kala-azar.

Question 10

African sleeping sickness is caused by

Accepted Answer

African sleeping sickness is caused by Trypanosoma brucei gambiense and Trypanosoma brucei rhodesiense.

Question 11

Which of the following fungi causes Valley fever in semi-arid regions of North American?

Accepted Answer

Valley fever, also known as coccidioidomycosis, is caused by the fungus Coccidioides immitis, which is found in semi-arid regions of North America. The other choices are other types of fungal infections but do not cause Valley fever.

Question 12

Vaccines are not effective against trypanosomiasis because

Accepted Answer

The organism that causes trypanosomiasis, Trypanosoma sp., can change its protein coat, making it difficult for the immune system to recognize and respond to the parasite. This means that even if a vaccine were developed, it may be ineffective as the parasite can rapidly evolve to evade the immune response.

Question 13

Which of the following is known to use tsetse flies as intermediate hosts?

Accepted Answer

Trypanosoma brucei gambiense, the causative agent of African sleeping sickness, is known to use tsetse flies as intermediate hosts.

Question 14

Most systemic mycoses are acquired from _________.

Accepted Answer

Most systemic mycoses are acquired by inhaling fungal spores from the environment. The spores can be found in soil, bird droppings, or other organic matter. Cutaneous mycoses can be acquired through puncture wounds, but are not considered systemic mycoses. Insect vectors can transmit certain diseases caused by fungi, such as histoplasmosis, but they are not the main mode of transmission for most systemic mycoses. Therefore, the best choice is B.

Question 15

Blastomyces dermatitidis causes _________.

Accepted Answer

Blastomyces dermatitidis causes blastomycosis, a fungal infection that primarily affects the lungs but can also spread to other parts of the body. Valley fever and San Joaquin fever are alternative names for coccidioidomycosis, another fungal infection caused by the species Coccidioides. Cryptococcosis is caused by the fungus Cryptococcus neoformans.

Question 16

In humans,Cryptococcus grows as a _________.

Accepted Answer

Cryptococcus primarily grows as a yeast. While it can exist in a hyphal form in certain conditions, it is not classified as a dimorphic fungus. It does not form a true mycelium.

Question 17

Which of the following is not caused by a protozoan?

Accepted Answer

Cryptococcosis is not caused by a protozoan, but by a fungus called Cryptococcus neoformans. The other choices (Cryptosporidiosis and African sleeping sickness) are protozoan infections.

Question 18

Once inside an erythrocyte,the Plasmodium begins to enlarge as a uninucleate cell called a _________.

Accepted Answer

Once inside the erythrocyte, the Plasmodium begins to enlarge as a uninucleate cell called a trophozoite. The trophozoite will then undergo several rounds of multiplication, resulting in the formation of a schizont. The schizont will then rupture and release merozoites, which can infect new erythrocytes and continue the cycle.

Question 19

Fungal diseases are usually divided into __________ groups according to the level of infected tissue and the mode of entry into the host.

Accepted Answer

The answer of Fungal diseases are usually divided into __________...

Question 20

Birds carry Histoplasma capsulatum.

Accepted Answer

Histoplasma capsulatum is a fungus that is primarily found in bird and bat droppings, but birds themselves do not carry the fungus.

Quiz 40: Human Diseases Caused by Fungi and Protists