Blood & Lymphatic Diseases

Question 1

Toxoplasmosis

Answer 1

Causative agent: Toxoplasma gondii protozoan
Cats are primary reservoir- infection is from ingestion of oocyst from feces or water contaminated by feces
Human infection usually by cleaning litter box and ingesting oocytes or ingesting undercooked meats containing cysts
Symptoms: most severe in immunocompromised and in pregnant women
TORCH organism- stillbirth, severe brain damage or vision problems
Very mild disease in healthy individuals

Question 2

Malaria

Answer 2

Causative agent: Plasmodium vivax & Plasmodium falciparum
Protozoa has complex life cycle- spread by Anopheles mosquitos with humans as intermediate host
Symptoms: recurrent violent chills and fever
Transmission: human (host) bitten by mosquito (vector) carrying infective stage of parasite –> migrates to the liver, where is multiplies asexually –> protozoan enters blood stream where it infects RBCs –> multiplies in RBC, which burst (rupture of RBC: waste is released into blood stream producing fever and chills)
Release from RBCs every 24 or 48 hours- fever is very precise and large numbers of progeny are released at once

Question 3

Cytomegalovirus (CMV)

Answer 3

Enveloped DNA herpesvirus family
80% of population has antibodies to virus: CMV can infect CNS, eyes, brain, liver, white blood cells + has the ability to depress CD4+ cell count, MHC expression
Symptoms: immunocompetent have few symptoms, mononucleosis-like disease in young adults, extremely problematic in immunosuppressed
Severe disease in fetus: congenital cytomegalic inclusion disease (characterized by jaundice, large live, anemia, and birth defects; 5-25% sequelae later in life)
Transmission: all body fluids, can be transmitted by organ donation, blood transfusion, sexually

Question 4

Epstein-Barr Virus (EBV)

Answer 4

Enveloped DNA virus, herpesvirus family
Infectious mononucleosis:
Virus infects oral epithelium then travels to lymph nodes where it infects B cells- my be productive infection-produces virons, may be non-productive-latent infection in B cells + causes production of heterophile antibodies, T cytotoxic cells control infection in cells making viral proteins + NK cells play a role when MHC molecules are downregulated
Signs and Symptoms: Fever, sore throat, swollen lymph nodes in neck, enlarged spleen and general weakness/exhaustion (lymph nodes and spleen enlarge from clonal expansion of non-specifically activated B vells)
Early childhood- mild/unnoticeable/asymptomatic
Post adolescence- more likely to have infectious mono signs and symptoms
Transmission is via saliva of infected individuals

Burkitt’s Lymphoma:
EBV infection
Primarily in individuals with Malaria
Common cause of childhood cancer in Africa

Question 5

Septicemia

Answer 5

Septic shock is most common with infections by gram-negative organisms, staphylococci, or meningococci
Increasing incidence with multi-drug resistant organisms
Toll-like receptors cause the release of a large number of mediators- tumor necrosis factor (TNF), leukotrienes, histamine, and IL-1
Endotoxin activates clotting factors and causes DIC. Endotoxin effect on macrophages in lungs can cause irreversible lung damage. Leaky blood vessels- patient will not respond to fluid replacement theory.
Early administration with antibiotics are life-saving. Antibiotics should be continued for several days after shock resolves.