Protozoa II Flashcards

Question

Sx of Infection with African trypanosomiasis

Answer 1

Multiply in blood stream and can eventually enter CNS • Leads to wasting with fever, severe headaches, irritability, extreme fatigue, swollen lymph nodes, and aching muscles and joints; CNS involvement later (progressive confusion, personality changes, and other neurologic problems) -Presence of parasites leads to meningo-encephalitis with progressive neurological involvement, which ultimately ends in coma (sleeping sickness) • Lethal if not treated

Answer 2

- Apicomplexan species that cause malaria - 2 hosts - Malaria infected Anopheles mosquito inoculates sporozoites into the human host - Sporozoites infect liver cells and mature into schizonts, which rupture and release merozoites - [P.vivax and ovale have dormant stage called hypnozoites that can persist in liver and causes relapses weeks or years later] - -Merozoites infect RBCs - Asexual replication in erythrocytes - Ring stage trophozoites mature into schizonts, which rupture releasing merozoites - Blood stage parasites are responsible for clinical manifestations - Gametocytes, formed in some erythrocytes (male: microgametocytes and female: macrogametocytes) are ingested by Anopheles mosquito during blood meal - Multiplication in mosquito= sporogonic cycle - Zygotes generated in mosquite become motile, elongated (ookinetes) which invade midgut wall of mosquito where they develop into oocysts - Oocysts rupture and release sporozoites

Answer 3

P. vivax, P. ovale, P. malariae, and P. falciparum Malaria affects over 1 billion people and causes 0.5-1 million deaths/year. P. falciparum causes most of the deaths. P falciparum can invade RBCs of all ages P. vivax and ovale invade younger RBCs P. malariae invades old RBCs

Answer 4

traditionally via parasites in blood (microscopy)

Answer 5

- 9-14 d incubation - symptoms of malaria are primarily associated with the rupture of infected erythrocytes and release of merozoites - The classical (but rarely observed) malaria attack lasts 6-10 hours. It consists of a cold stage (sensation of cold, shivering) a hot stage (fever, headaches, vomiting; seizures in young children) and finally a sweating stage (sweats, return to normal temperature, tiredness). - See: fever and flu-like illness, including shaking chills, headache, muscle aches, and tiredness Regular periodicity of fever paroxysms if pt untreated: 48 hrs for benign tertian malaria caused by P. vivax or P. ovale; 72 hr. for quartan malaria caused by P. malariae; and 36-48 hr. for malignant tertian malaria caused by P. falciparum. Anemia: lysis of RBCs, but also from their phagocytosis by the stimulated reticuloendothelial system, their sequestration in the enlarged spleen, and depressed bone marrow function Physical examination reveals jaundice, hypotension and tachycardia in addition to fever and hepatosplenomegaly P. falciparum-infected red blood cells bind to the microvascular endothelium, which is especially significant in cerebral malaria (up to 50% mortality). Multi-organ failure is the major cause of death in adults. With P. malariae infections, immune complex deposition leading to glomerulonephritis is common.

Answer 6

P. vivax is widely distributed from tropical to temperate zones, but P. falciparum occurs primarily in the tropics and subtropics. P. falciparum prevalence has selected for traits like sickle cell, thalassemia, G6PD deficiency

Answer 7

PfEMP1 (P. falciparum erythrocyte membrane protein) Infected RBCs will adhere to the endothelium as well as to each other and cause clogging and hemmorhaging • Response of host to adhering parasites is to make high cytokine levels which induce expression of endothelial adhesins leading to inflammation which makes the endothelia ‘stickier’ • Adherence and inflammation reinforce each other in an unholy circle causing pathology

Answer 8

-eliminated from US in early 1950s -1,500–2,000 cases of malaria are reported every year in the United States, almost all in recent travelers • First- and second-generation immigrants returning to their home countries to visit friends and relatives tend not to use appropriate malaria prevention measures and thus are more likely to become infected with malaria Immunity to malaria relatively weak (variants and antigenic variation), but some exists

Answer 9

Mosquito Control o Reduction of mosquito numbers (DDT issue) • Reduce mosquito bites o Insecticide impregnated bed nets • Prophylactic Treatment o Leads to drug resistance • Treatment: o New drugs needed as drug resistance readily develops o Why? Attribute of parasite and massive replication Behavioral factors: housing, use of bed nets, financial situation, standing water, agricultural work, domestic animals (reservoir hosts), war, and migration

Answer 10

Negative for the Duffy blood group have rbc resistant to infection by P. vivax

Answer 11

- 2 hosts (rodent and Ixodes tick) - tick takes a blood meal and sporozoites introduced into mouse host - Sporozoites enter erythrocytes and asexual replication occurs - In blood, parasites differentiate into male and female gametes - These are ingested by tick, gametes unite and eventually results in sporozoites - Tick introduces sporozoites into human host - Sporozoites enter erythrocytes, asexual replication occurs - Multiplication of the blood-stage parasites is responsible for the clinical manifestations of the disease. Humans usually are dead-end hosts but human to human transmission occurs via blood transfusions

Answer 12

US mainly occurs in parts of the Northeast and upper Midwest and usually peaks during the warm months (1,800 cases in 2013) • Transmission may also occur from blood transfusion and to fetus

Answer 13

-ranges in severity from asymptomatic to life threatening • Can be a severe, life-threatening disease, particularly in people who do not have a spleen, immunocompromised, elderly, or weak liver or spleen • Some people develop flu-like symptoms, such as fever, chills, sweats, headache, body aches, loss of appetite, nausea, or fatigue. • Because Babesia parasites infect red blood cells, babesiosis can cause hemolytic anemia

Answer 14

examining blood specimens under a microscope and seeing Babesia parasites inside red blood cells