Toxoplasma/Toxoplasmosis

General Characteristics and Epidemiology

General features of Toxoplasma

General characteristics:

• Obligate intracellular parasite
• Protozoan parasite

Morphologic forms:

• Oocyst:
  • Shed in feline feces
  • Takes 1–5 days to sporulate in the environment and become infective
• Tachyzoite (also called trophozoite):
  • Obligate intracellular form 
  • Crescent-shaped form with a central nucleus Nucleus Within a eukaryotic cell, a membrane-limited body which contains chromosomes and one or more nucleoli (cell nucleolus). The nuclear membrane consists of a double unit-type membrane which is perforated by a number of pores; the outermost membrane is continuous with the endoplasmic reticulum. A cell may contain more than one nucleus. The Cell: Organelles
  • Responsible for cell invasion and clinical disease
  • Multiplies rapidly
• Bradyzoite:
  • Quiescent
  • Forms a thick wall around itself (tissue cyst)
  • Resistant to digestive enzymes Enzymes Enzymes are complex protein biocatalysts that accelerate chemical reactions without being consumed by them. Due to the body’s constant metabolic needs, the absence of enzymes would make life unsustainable, as reactions would occur too slowly without these molecules. Basics of Enzymes
  • Killed by freezing and normal cooking temperatures

Clinically relevant species

Toxoplasmosis is caused by Toxoplasma gondii.

Epidemiology

• Found worldwide, but more common in tropical regions
• 225,000 cases reported each year in the United States
• Approximately 50% of individuals have antibodies Antibodies Immunoglobulins (Igs), also known as antibodies, are glycoprotein molecules produced by plasma cells that act in immune responses by recognizing and binding particular antigens. The various Ig classes are IgG (the most abundant), IgM, IgE, IgD, and IgA, which differ in their biologic features, structure, target specificity, and distribution. Immunoglobulins: Types and Functions against T. gondii:
  • Approximately 11% of the population > 6 years of age in the United States
  • Up to 78% of the population in some areas of Brazil

Pathogenesis

Hosts

• Felines are the only definitive host.
• Infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease can occur in a wide range of vertebrate intermediate hosts (including humans).

Transmission

• Oral route:
  • Ingestion of oocysts passed in the feces of infected felines 
  • Ingestion of infected meat that is raw or undercooked (tissue cyst form Cyst form Pneumocystis jirovecii/Pneumocystis Pneumonia (PCP))
• Blood transfusion or organ transplantation Organ Transplantation Transplantation is a procedure that involves the removal of an organ or living tissue and placing it into a different part of the body or into a different person. Organ transplantations have become the therapeutic option of choice for many individuals with end-stage organ failure. Organ Transplantation 
• Vertical transmission Vertical transmission The transmission of infectious disease or pathogens from one generation to another. It includes transmission in utero or intrapartum by exposure to blood and secretions, and postpartum exposure via breastfeeding. Congenital TORCH Infections

Life cycle and pathophysiology

Life cycle:

• Oocysts are shed in the cat’s feces → ingested by an intermediate host (e.g., mammals, birds)
• Oocysts transform into tachyzoites → localize in neural and muscle tissues → develop into tissue cysts Cysts Any fluid-filled closed cavity or sac that is lined by an epithelium. Cysts can be of normal, abnormal, non-neoplastic, or neoplastic tissues. Fibrocystic Change
• Cat consumes an infected intermediate host’s tissue → organism undergoes sexual cycle → cycle continues 

Life cycle and pathophysiology in humans:

• Transmission to a human host → bradyzoites released from cysts Cysts Any fluid-filled closed cavity or sac that is lined by an epithelium. Cysts can be of normal, abnormal, non-neoplastic, or neoplastic tissues. Fibrocystic Change (or sporozoites Sporozoites The product of meiotic division of zygotes in parasitic protozoa comprising haploid cells. These infective cells invade the host and undergo asexual reproduction producing merozoites (or other forms) and ultimately gametocytes. Antimalarial Drugs from oocysts)
• Transformation Transformation Change brought about to an organism’s genetic composition by unidirectional transfer (transfection; transduction, genetic; conjugation, genetic, etc.) and incorporation of foreign DNA into prokaryotic or eukaryotic cells by recombination of part or all of that DNA into the cell’s genome. Bacteriology to tachyzoites → multiply rapidly in GI cells → rupture cells
• Transported in the lymphatics and disseminate in the bloodstream to:
  • Skeletal muscle
  • Myocardium Myocardium The muscle tissue of the heart. It is composed of striated, involuntary muscle cells connected to form the contractile pump to generate blood flow. Heart: Anatomy
  • Brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification
  • Eyes
• Immune system Immune system The body’s defense mechanism against foreign organisms or substances and deviant native cells. It includes the humoral immune response and the cell-mediated response and consists of a complex of interrelated cellular, molecular, and genetic components. Primary Lymphatic Organs generally controls the replication of tachyzoites.
• Bradyzoites develop cysts Cysts Any fluid-filled closed cavity or sac that is lined by an epithelium. Cysts can be of normal, abnormal, non-neoplastic, or neoplastic tissues. Fibrocystic Change and remain dormant → can remain dormant for years

Clinical Presentation

The clinical presentation of toxoplasmosis can vary depending on the host’s immune function and organs involved. The following table summarizes the various diseases:

Diagnosis

The diagnostic workup will be guided by the patient’s clinical presentation.

Laboratory evaluation

• Serologic testing ( ELISA ELISA An immunoassay utilizing an antibody labeled with an enzyme marker such as horseradish peroxidase. While either the enzyme or the antibody is bound to an immunosorbent substrate, they both retain their biologic activity; the change in enzyme activity as a result of the enzyme-antibody-antigen reaction is proportional to the concentration of the antigen and can be measured spectrophotometrically or with the naked eye. Many variations of the method have been developed. St. Louis Encephalitis Virus):
  • IgM IgM A class of immunoglobulin bearing mu chains (immunoglobulin mu-chains). Igm can fix complement. The name comes from its high molecular weight and originally being called a macroglobulin. Immunoglobulins: Types and Functions antibodies Antibodies Immunoglobulins (Igs), also known as antibodies, are glycoprotein molecules produced by plasma cells that act in immune responses by recognizing and binding particular antigens. The various Ig classes are IgG (the most abundant), IgM, IgE, IgD, and IgA, which differ in their biologic features, structure, target specificity, and distribution. Immunoglobulins: Types and Functions:
    • Appear within 1 week of symptom onset
    • A positive test indicates active infection.
  • IgG IgG The major immunoglobulin isotype class in normal human serum. There are several isotype subclasses of igg, for example, igg1, igg2a, and igg2b. Hypersensitivity Pneumonitis antibodies Antibodies Immunoglobulins (Igs), also known as antibodies, are glycoprotein molecules produced by plasma cells that act in immune responses by recognizing and binding particular antigens. The various Ig classes are IgG (the most abundant), IgM, IgE, IgD, and IgA, which differ in their biologic features, structure, target specificity, and distribution. Immunoglobulins: Types and Functions:
    • Appear within 2 weeks of symptom onset
    • Persist for life
• PCR PCR Polymerase chain reaction (PCR) is a technique that amplifies DNA fragments exponentially for analysis. The process is highly specific, allowing for the targeting of specific genomic sequences, even with minuscule sample amounts. The PCR cycles multiple times through 3 phases: denaturation of the template DNA, annealing of a specific primer to the individual DNA strands, and synthesis/elongation of new DNA molecules. Polymerase Chain Reaction (PCR):
  • Detects parasite DNA DNA A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine). DNA Types and Structure
  • Samples can be obtained from:
    • Blood
    • CSF
    • Aqueous humor Humor Defense Mechanisms
    • Bronchoalveolar lavage Bronchoalveolar lavage Washing out of the lungs with saline or mucolytic agents for diagnostic or therapeutic purposes. It is very useful in the diagnosis of diffuse pulmonary infiltrates in immunosuppressed patients. Pulmonary Fibrosis
• Supporting laboratory studies:
  • Negative heterophile antibody test → rules out mononucleosis Mononucleosis Infectious mononucleosis (IM), also known as “the kissing disease,” is a highly contagious viral infection caused by the Epstein-Barr virus. Its common name is derived from its main method of transmission: the spread of infected saliva via kissing. Clinical manifestations of IM include fever, tonsillar pharyngitis, and lymphadenopathy. Mononucleosis
  • Lymphocytosis Lymphocytosis WBCs develop from stem cells in the bone marrow and are called leukocytes when circulating in the bloodstream. Lymphocytes are 1 of the 5 subclasses of WBCs. Lymphocytosis is an increase in the number or proportion of the lymphocyte subclass of WBCs, often as a result of an immune response to infection (known as reactive lymphocytosis). Lymphocytosis (with or without atypical cells)
  • Mild transaminitis Transaminitis Tick-borne Encephalitis Virus

Histopathology

• Provides a definitive diagnosis, but rarely required
• Lymph Lymph The interstitial fluid that is in the lymphatic system. Secondary Lymphatic Organs node findings:
  • Reactive follicular hyperplasia Hyperplasia An increase in the number of cells in a tissue or organ without tumor formation. It differs from hypertrophy, which is an increase in bulk without an increase in the number of cells. Cellular Adaptation
  • Irregular clusters of tissue macrophages Macrophages The relatively long-lived phagocytic cell of mammalian tissues that are derived from blood monocytes. Main types are peritoneal macrophages; alveolar macrophages; histiocytes; kupffer cells of the liver; and osteoclasts. They may further differentiate within chronic inflammatory lesions to epithelioid cells or may fuse to form foreign body giant cells or langhans giant cells. Innate Immunity: Phagocytes and Antigen Presentation with eosinophilic cytoplasm
• Brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification findings:
  • Patchy, diffuse encephalitis Encephalitis Encephalitis is inflammation of the brain parenchyma caused by an infection, usually viral. Encephalitis may present with mild symptoms such as headache, fever, fatigue, and muscle and joint pain or with severe symptoms such as seizures, altered consciousness, and paralysis. Encephalitis
  • Cyst lesions
  • Necrotic regions
  • Granulomas Granulomas A relatively small nodular inflammatory lesion containing grouped mononuclear phagocytes, caused by infectious and noninfectious agents. Sarcoidosis
  • Lymphocytic vasculitis Vasculitis Inflammation of any one of the blood vessels, including the arteries; veins; and rest of the vasculature system in the body. Systemic Lupus Erythematosus
• Ocular findings:
  • Segmental panophthalmitis Panophthalmitis Acute suppurative inflammation of the inner eye with necrosis of the sclera (and sometimes the cornea) and extension of the inflammation into the orbit. Pain may be severe and the globe may rupture. In endophthalmitis the globe does not rupture. Relapsing Fever
  • Necrosis Necrosis The death of cells in an organ or tissue due to disease, injury or failure of the blood supply. Ischemic Cell Damage
  • Tissue cysts Cysts Any fluid-filled closed cavity or sac that is lined by an epithelium. Cysts can be of normal, abnormal, non-neoplastic, or neoplastic tissues. Fibrocystic Change and tachyzoites

Imaging

Brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification imaging may be performed if CNS or congenital toxoplasmosis is suspected.

• Options:
  • CT
  • MRI
• Findings in CNS toxoplasmosis CNS toxoplasmosis Infections of the brain caused by the protozoan toxoplasma gondii that primarily arise in individuals with immunologic deficiency syndromes. The infection may involve the brain diffusely or form discrete abscesses. Clinical manifestations include seizures, altered mentation, headache, focal neurologic deficits, and intracranial hypertension. AIDS-defining Conditions:
  • Single or multiple ring-enhancing lesions
  • Inflammatory changes
• Findings in congenital toxoplasmosis:
  • Scattered calcifications 
  • Hydrocephalus Hydrocephalus Excessive accumulation of cerebrospinal fluid within the cranium which may be associated with dilation of cerebral ventricles, intracranial. Subarachnoid Hemorrhage 
  • Cortical atrophy Atrophy Decrease in the size of a cell, tissue, organ, or multiple organs, associated with a variety of pathological conditions such as abnormal cellular changes, ischemia, malnutrition, or hormonal changes. Cellular Adaptation

Management and Prevention

Management

Patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship who are immunocompetent typically do not require treatment. However, treatment is needed for patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship who are immunocompromised immunocompromised A human or animal whose immunologic mechanism is deficient because of an immunodeficiency disorder or other disease or as the result of the administration of immunosuppressive drugs or radiation. Gastroenteritis, pregnant, or with severe or prolonged symptoms.

• Combination medical therapy:
  • Pyrimethamine Pyrimethamine One of the folic acid antagonists that is used as an antimalarial or with a sulfonamide to treat toxoplasmosis. Antimalarial Drugs (inhibits dihydrofolate reductase Dihydrofolate Reductase Sulfonamides and Trimethoprim)
  • Sulfadiazine Sulfadiazine One of the short-acting sulfonamides used in combination with pyrimethamine to treat toxoplasmosis in patients with acquired immunodeficiency syndrome and in newborns with congenital infections. Sulfonamides and Trimethoprim (inhibits dihydropteroate synthetase)
  • Leucovorin (folinic acid, prevents folic acid deficiency Folic Acid Deficiency A nutritional condition produced by a deficiency of folic acid in the diet. Many plant and animal tissues contain folic acid, abundant in green leafy vegetables, yeast, liver, and mushrooms but destroyed by long-term cooking. Alcohol interferes with its intermediate metabolism and absorption. Folic acid deficiency may develop in long-term anticonvulsant therapy or with use of oral contraceptives. This deficiency causes anemia, macrocytic anemia, and megaloblastic anemia. It is indistinguishable from vitamin B 12 deficiency in peripheral blood and bone marrow findings, but the neurologic lesions seen in B 12 deficiency do not occur. Megaloblastic Anemia)
• Corticosteroids Corticosteroids Chorioretinitis may be added in CNS toxoplasmosis CNS toxoplasmosis Infections of the brain caused by the protozoan toxoplasma gondii that primarily arise in individuals with immunologic deficiency syndromes. The infection may involve the brain diffusely or form discrete abscesses. Clinical manifestations include seizures, altered mentation, headache, focal neurologic deficits, and intracranial hypertension. AIDS-defining Conditions to reduce cerebral edema Cerebral edema Increased intracellular or extracellular fluid in brain tissue. Cytotoxic brain edema (swelling due to increased intracellular fluid) is indicative of a disturbance in cell metabolism, and is commonly associated with hypoxic or ischemic injuries. An increase in extracellular fluid may be caused by increased brain capillary permeability (vasogenic edema), an osmotic gradient, local blockages in interstitial fluid pathways, or by obstruction of CSF flow (e.g., obstructive hydrocephalus). Increased Intracranial Pressure (ICP) if mass Mass Three-dimensional lesion that occupies a space within the breast Imaging of the Breast effect is present.
• Ensure that patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with AIDS are started on antiretroviral therapy Antiretroviral therapy Antiretroviral therapy (ART) targets the replication cycle of the human immunodeficiency virus (HIV) and is classified based on the viral enzyme or mechanism that is inhibited. The goal of therapy is to suppress viral replication to reach the outcome of undetected viral load. Anti-HIV Drugs.

Prevention and prophylaxis Prophylaxis Cephalosporins

• General advice:
  • Wash hands after handling raw meat or cat litter.
  • Thoroughly cook meat.
• Pregnant patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship:
  • Routine antibody screening Screening Preoperative Care in pregnant women is not recommended.
  • Avoid cats.
  • Do not clean litter boxes (if unavoidable, wear gloves).
• Patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with AIDS: long-term sulfamethoxazole-trimethoprim when CD4 < 100 cells/µL

Differential Diagnosis

• Infectious mononucleosis Mononucleosis Infectious mononucleosis (IM), also known as “the kissing disease,” is a highly contagious viral infection caused by the Epstein-Barr virus. Its common name is derived from its main method of transmission: the spread of infected saliva via kissing. Clinical manifestations of IM include fever, tonsillar pharyngitis, and lymphadenopathy. Mononucleosis: a disease caused by EBV EBV Epstein-barr virus (EBV) is a linear, double-stranded DNA virus belonging to the herpesviridae family. This highly prevalent virus is mostly transmitted through contact with oropharyngeal secretions from an infected individual. The virus can infect epithelial cells and B lymphocytes, where it can undergo lytic replication or latency. Epstein-Barr Virus that is characterized by fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever, fatigue Fatigue The state of weariness following a period of exertion, mental or physical, characterized by a decreased capacity for work and reduced efficiency to respond to stimuli. Fibromyalgia, lymphadenopathy Lymphadenopathy Lymphadenopathy is lymph node enlargement (> 1 cm) and is benign and self-limited in most patients. Etiologies include malignancy, infection, and autoimmune disorders, as well as iatrogenic causes such as the use of certain medications. Generalized lymphadenopathy often indicates underlying systemic disease. Lymphadenopathy, and pharyngitis Pharyngitis Pharyngitis is an inflammation of the back of the throat (pharynx). Pharyngitis is usually caused by an upper respiratory tract infection, which is viral in most cases. It typically results in a sore throat and fever. Other symptoms may include a runny nose, cough, headache, and hoarseness. Pharyngitis. Atypical lymphocytosis Lymphocytosis WBCs develop from stem cells in the bone marrow and are called leukocytes when circulating in the bloodstream. Lymphocytes are 1 of the 5 subclasses of WBCs. Lymphocytosis is an increase in the number or proportion of the lymphocyte subclass of WBCs, often as a result of an immune response to infection (known as reactive lymphocytosis). Lymphocytosis may be seen. The diagnosis is based on clinical features and tests, such as a positive heterophile antibody test or serology Serology The study of serum, especially of antigen-antibody reactions in vitro. Yellow Fever Virus. Management is supportive. 
• CMV mononucleosis CMV mononucleosis Cytomegalovirus: a disease caused by CMV. Patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship may present with fevers, lymphadenopathy Lymphadenopathy Lymphadenopathy is lymph node enlargement (> 1 cm) and is benign and self-limited in most patients. Etiologies include malignancy, infection, and autoimmune disorders, as well as iatrogenic causes such as the use of certain medications. Generalized lymphadenopathy often indicates underlying systemic disease. Lymphadenopathy, hepatitis, and atypical lymphocytosis Lymphocytosis WBCs develop from stem cells in the bone marrow and are called leukocytes when circulating in the bloodstream. Lymphocytes are 1 of the 5 subclasses of WBCs. Lymphocytosis is an increase in the number or proportion of the lymphocyte subclass of WBCs, often as a result of an immune response to infection (known as reactive lymphocytosis). Lymphocytosis. However, pharyngitis Pharyngitis Pharyngitis is an inflammation of the back of the throat (pharynx). Pharyngitis is usually caused by an upper respiratory tract infection, which is viral in most cases. It typically results in a sore throat and fever. Other symptoms may include a runny nose, cough, headache, and hoarseness. Pharyngitis is absent. Positive CMV serologic testing provides the diagnosis. The disease is self-limiting Self-Limiting Meningitis in Children.
• Acute human immunodeficiency Immunodeficiency Chédiak-Higashi Syndrome virus Virus Viruses are infectious, obligate intracellular parasites composed of a nucleic acid core surrounded by a protein capsid. Viruses can be either naked (non-enveloped) or enveloped. The classification of viruses is complex and based on many factors, including type and structure of the nucleoid and capsid, the presence of an envelope, the replication cycle, and the host range. Virology ( HIV HIV Anti-HIV Drugs) infection: a sexually transmitted or blood-borne disease caused by HIV HIV Anti-HIV Drugs. The presentation of HIV HIV Anti-HIV Drugs is marked by constitutional symptoms Constitutional Symptoms Antineutrophil Cytoplasmic Antibody (ANCA)-Associated Vasculitis such as lymphadenopathy Lymphadenopathy Lymphadenopathy is lymph node enlargement (> 1 cm) and is benign and self-limited in most patients. Etiologies include malignancy, infection, and autoimmune disorders, as well as iatrogenic causes such as the use of certain medications. Generalized lymphadenopathy often indicates underlying systemic disease. Lymphadenopathy and fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever. Further progression may lead to opportunistic infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease and malignancies. Diagnosis is by enzyme immunoassay Enzyme immunoassay HIV Infection and AIDS. Additional tests include HIV HIV Anti-HIV Drugs viral load Viral load The quantity of measurable virus in a body fluid. Change in viral load, measured in plasma, is sometimes used as a surrogate marker in disease progression. HIV Infection and AIDS determination, genotyping Genotyping Methods used to determine individuals’ specific alleles or snps (single nucleotide polymorphisms). Polymerase Chain Reaction (PCR), and CD4+ T lymphocyte count Lymphocyte count The number of lymphocytes per unit volume of blood. Lymphocytosis. Immediate treatment with combination antiretroviral therapy Antiretroviral therapy Antiretroviral therapy (ART) targets the replication cycle of the human immunodeficiency virus (HIV) and is classified based on the viral enzyme or mechanism that is inhibited. The goal of therapy is to suppress viral replication to reach the outcome of undetected viral load. Anti-HIV Drugs is recommended.
• Tularemia: a rare infection caused by Francisella tularensis Francisella Tularensis Aminoglycosides acquired by contact with animal tissue, ticks Ticks Blood-sucking acarid parasites of the order ixodida comprising two families: the softbacked ticks (argasidae) and hardbacked ticks (ixodidae). Ticks are larger than their relatives, the mites. They penetrate the skin of their host by means of highly specialized, hooked mouth parts and feed on its blood. Ticks attack all groups of terrestrial vertebrates. In humans they are responsible for many tick-borne diseases, including the transmission of rocky mountain spotted fever; tularemia; babesiosis; african swine fever; and relapsing fever. Coxiella/Q Fever, or biting flies. The infection manifests as a papule Papule Elevated lesion < 1 cm in diameter Generalized and Localized Rashes, followed by fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever, headache Headache The symptom of pain in the cranial region. It may be an isolated benign occurrence or manifestation of a wide variety of headache disorders. Brain Abscess, and suppurative lymphadenopathy Lymphadenopathy Lymphadenopathy is lymph node enlargement (> 1 cm) and is benign and self-limited in most patients. Etiologies include malignancy, infection, and autoimmune disorders, as well as iatrogenic causes such as the use of certain medications. Generalized lymphadenopathy often indicates underlying systemic disease. Lymphadenopathy. Tularemia may have multiorgan involvement. Diagnosis is based on culture of blood and infected tissues. Treatment is with antibiotics.
• Cat-scratch disease Cat-scratch disease A self-limiting bacterial infection of the regional lymph nodes caused by afipia felis, a gram-negative bacterium recently identified by the centers for disease control and prevention and by Bartonella henselae. It usually arises one or more weeks following a feline scratch, with raised inflammatory nodules at the site of the scratch being the primary symptom. Bartonella: an infection caused by Bartonella henselae Bartonella henselae A species of gram-negative bacteria that is the etiologic agent of bacillary angiomatosis. This organism can also be a cause of cat-scratch disease in immunocompetent patients. Bartonella, a gram-negative bacillus Bacillus Bacillus are aerobic, spore-forming, gram-positive bacilli. Two pathogenic species are Bacillus anthracis (B. anthracis) and B. cereus. Bacillus. Patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship usually present with fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever, weight loss Weight loss Decrease in existing body weight. Bariatric Surgery, and tender lymphadenopathy Lymphadenopathy Lymphadenopathy is lymph node enlargement (> 1 cm) and is benign and self-limited in most patients. Etiologies include malignancy, infection, and autoimmune disorders, as well as iatrogenic causes such as the use of certain medications. Generalized lymphadenopathy often indicates underlying systemic disease. Lymphadenopathy after being bitten or scratched by a cat. The diagnosis is confirmed with serology Serology The study of serum, especially of antigen-antibody reactions in vitro. Yellow Fever Virus or PCR PCR Polymerase chain reaction (PCR) is a technique that amplifies DNA fragments exponentially for analysis. The process is highly specific, allowing for the targeting of specific genomic sequences, even with minuscule sample amounts. The PCR cycles multiple times through 3 phases: denaturation of the template DNA, annealing of a specific primer to the individual DNA strands, and synthesis/elongation of new DNA molecules. Polymerase Chain Reaction (PCR). Symptomatic treatment is recommended and azithromycin Azithromycin A semi-synthetic macrolide antibiotic structurally related to erythromycin. It has been used in the treatment of Mycobacterium avium intracellulare infections, toxoplasmosis, and cryptosporidiosis. Macrolides and Ketolides is given for severe illness.
• Extrapulmonary tuberculosis Tuberculosis Tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis complex bacteria. The bacteria usually attack the lungs but can also damage other parts of the body. Approximately 30% of people around the world are infected with this pathogen, with the majority harboring a latent infection. Tuberculosis spreads through the air when a person with active pulmonary infection coughs or sneezes. Tuberculosis: a disseminated mycobacterial infection. The presentation of extrapulmonary tuberculosis Tuberculosis Tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis complex bacteria. The bacteria usually attack the lungs but can also damage other parts of the body. Approximately 30% of people around the world are infected with this pathogen, with the majority harboring a latent infection. Tuberculosis spreads through the air when a person with active pulmonary infection coughs or sneezes. Tuberculosis includes meningitis Meningitis Meningitis is inflammation of the meninges, the protective membranes of the brain, and spinal cord. The causes of meningitis are varied, with the most common being bacterial or viral infection. The classic presentation of meningitis is a triad of fever, altered mental status, and nuchal rigidity. Meningitis, pericarditis Pericarditis Pericarditis is an inflammation of the pericardium, often with fluid accumulation. It can be caused by infection (often viral), myocardial infarction, drugs, malignancies, metabolic disorders, autoimmune disorders, or trauma. Acute, subacute, and chronic forms exist. Pericarditis, lymphadenitis Lymphadenitis Inflammation of the lymph nodes. Peritonsillar Abscess, and liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver: Anatomy infection, and can vary depending on the site involved. The diagnosis is based on the detection of acid-fast bacilli Acid-fast bacilli Mycobacterium by culturing body fluids or tissue samples. Treatment involves combination therapy with isoniazid Isoniazid Antibacterial agent used primarily as a tuberculostatic. It remains the treatment of choice for tuberculosis. Antimycobacterial Drugs, rifampin Rifampin A semisynthetic antibiotic produced from streptomyces mediterranei. It has a broad antibacterial spectrum, including activity against several forms of Mycobacterium. In susceptible organisms it inhibits dna-dependent RNA polymerase activity by forming a stable complex with the enzyme. It thus suppresses the initiation of RNA synthesis. Rifampin is bactericidal, and acts on both intracellular and extracellular organisms. Epiglottitis, pyrazinamide Pyrazinamide A pyrazine that is used therapeutically as an antitubercular agent. Antimycobacterial Drugs, and ethambutol Ethambutol An antitubercular agent that inhibits the transfer of mycolic acids into the cell wall of the tubercle Bacillus. It may also inhibit the synthesis of spermidine in mycobacteria. The action is usually bactericidal, and the drug can penetrate human cell membranes to exert its lethal effect. Antimycobacterial Drugs.
• Hodgkin disease Hodgkin Disease A malignant disease characterized by progressive enlargement of the lymph nodes, spleen, and general lymphoid tissue. In the classical variant, giant usually multinucleate hodgkin’s and reed-sternberg cells are present; in the nodular lymphocyte predominant variant, lymphocytic and histiocytic cells are seen. Hodgkin Lymphoma: a malignancy Malignancy Hemothorax of B lymphocytes B lymphocytes Lymphoid cells concerned with humoral immunity. They are short-lived cells resembling bursa-derived lymphocytes of birds in their production of immunoglobulin upon appropriate stimulation. B cells: Types and Functions within the lymph nodes Lymph Nodes They are oval or bean shaped bodies (1 – 30 mm in diameter) located along the lymphatic system. Lymphatic Drainage System: Anatomy. Patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship present with lymphadenopathy Lymphadenopathy Lymphadenopathy is lymph node enlargement (> 1 cm) and is benign and self-limited in most patients. Etiologies include malignancy, infection, and autoimmune disorders, as well as iatrogenic causes such as the use of certain medications. Generalized lymphadenopathy often indicates underlying systemic disease. Lymphadenopathy, night sweats Night sweats Tuberculosis, weight loss Weight loss Decrease in existing body weight. Bariatric Surgery, fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever, splenomegaly Splenomegaly Splenomegaly is pathologic enlargement of the spleen that is attributable to numerous causes, including infections, hemoglobinopathies, infiltrative processes, and outflow obstruction of the portal vein. Splenomegaly, and hepatomegaly. Diagnostic tests Diagnostic tests Diagnostic tests are important aspects in making a diagnosis. Some of the most important epidemiological values of diagnostic tests include sensitivity and specificity, false positives and false negatives, positive and negative predictive values, likelihood ratios, and pre-test and post-test probabilities. Epidemiological Values of Diagnostic Tests include lymph Lymph The interstitial fluid that is in the lymphatic system. Secondary Lymphatic Organs node histological analysis, blood tests, CT, and PET PET An imaging technique that combines a positron-emission tomography (PET) scanner and a ct X ray scanner. This establishes a precise anatomic localization in the same session. Nuclear Imaging. Management includes chemotherapy Chemotherapy Osteosarcoma and radiotherapy.
• Neurocysticercosis Neurocysticercosis Infection of the brain, spinal cord, or perimeningeal structures with the larval forms of the genus taenia (primarily T. solium in humans). Lesions formed by the organism are referred to as cysticerci. The infection may be subacute or chronic, and the severity of symptoms depends on the severity of the host immune response and the location and number of lesions. Seizures represent the most common clinical manifestation although focal neurologic deficits may occur. Taenia/Taeniasis: an infection caused by ingestion of Taenia Taenia Taenia belong to the Cestoda class of helminths. Humans are infected with these tapeworms by eating undercooked beef (T. saginata) or pork (T. solium and T. asiatica). Taeniasis is often asymptomatic, but the ingestion of larvae can cause abdominal discomfort, nausea, and constipation or diarrhea. Taenia/Taeniasis solium eggs. Cysts Cysts Any fluid-filled closed cavity or sac that is lined by an epithelium. Cysts can be of normal, abnormal, non-neoplastic, or neoplastic tissues. Fibrocystic Change can form anywhere in the CNS and cause personality changes, seizures Seizures A seizure is abnormal electrical activity of the neurons in the cerebral cortex that can manifest in numerous ways depending on the region of the brain affected. Seizures consist of a sudden imbalance that occurs between the excitatory and inhibitory signals in cortical neurons, creating a net excitation. The 2 major classes of seizures are focal and generalized. Seizures, focal neurologic deficits Neurologic Deficits High-Risk Headaches, or signs of intracranial hypertension Hypertension Hypertension, or high blood pressure, is a common disease that manifests as elevated systemic arterial pressures. Hypertension is most often asymptomatic and is found incidentally as part of a routine physical examination or during triage for an unrelated medical encounter. Hypertension. The diagnosis is usually made based on the “swiss cheese” appearance of the brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification on MRI or CT. Serology Serology The study of serum, especially of antigen-antibody reactions in vitro. Yellow Fever Virus may also be useful. Management is controversial, but may include steroids Steroids A group of polycyclic compounds closely related biochemically to terpenes. They include cholesterol, numerous hormones, precursors of certain vitamins, bile acids, alcohols (sterols), and certain natural drugs and poisons. Steroids have a common nucleus, a fused, reduced 17-carbon atom ring system, cyclopentanoperhydrophenanthrene. Most steroids also have two methyl groups and an aliphatic side-chain attached to the nucleus. Benign Liver Tumors, anthelmintic therapy Anthelmintic therapy Agents that kill parasitic worms. They are used therapeutically in the treatment of helminthiasis in man and animal. Toxocariasis, and neurosurgical consultation.
• Intracranial tumors: a benign Benign Fibroadenoma or malignant growth of cells in the brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification that present as headache Headache The symptom of pain in the cranial region. It may be an isolated benign occurrence or manifestation of a wide variety of headache disorders. Brain Abscess, unexplained nausea Nausea An unpleasant sensation in the stomach usually accompanied by the urge to vomit. Common causes are early pregnancy, sea and motion sickness, emotional stress, intense pain, food poisoning, and various enteroviruses. Antiemetics or vomiting Vomiting The forcible expulsion of the contents of the stomach through the mouth. Hypokalemia, blurred vision Blurred Vision Retinal Detachment, and difficulty in speech or hearing. The diagnosis is made with a neurologic examination, imaging (MRI or CT), and, sometimes, biopsy Biopsy Removal and pathologic examination of specimens from the living body. Ewing Sarcoma. Management includes radiation Radiation Emission or propagation of acoustic waves (sound), electromagnetic energy waves (such as light; radio waves; gamma rays; or x-rays), or a stream of subatomic particles (such as electrons; neutrons; protons; or alpha particles). Osteosarcoma, chemotherapy Chemotherapy Osteosarcoma, and/or surgery.
• Brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification abscess Abscess Accumulation of purulent material in tissues, organs, or circumscribed spaces, usually associated with signs of infection. Chronic Granulomatous Disease: a collection of pus in the brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification parenchyma due to an infection. A brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification abscess Abscess Accumulation of purulent material in tissues, organs, or circumscribed spaces, usually associated with signs of infection. Chronic Granulomatous Disease presents with fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever, headaches, seizures Seizures A seizure is abnormal electrical activity of the neurons in the cerebral cortex that can manifest in numerous ways depending on the region of the brain affected. Seizures consist of a sudden imbalance that occurs between the excitatory and inhibitory signals in cortical neurons, creating a net excitation. The 2 major classes of seizures are focal and generalized. Seizures, nausea Nausea An unpleasant sensation in the stomach usually accompanied by the urge to vomit. Common causes are early pregnancy, sea and motion sickness, emotional stress, intense pain, food poisoning, and various enteroviruses. Antiemetics, and vomiting Vomiting The forcible expulsion of the contents of the stomach through the mouth. Hypokalemia. The diagnosis is mainly based on imaging, as it is difficult to arrive at a definitive diagnosis based on clinical presentation alone. Management includes antibiotic therapy and surgery to drain the abscess Abscess Accumulation of purulent material in tissues, organs, or circumscribed spaces, usually associated with signs of infection. Chronic Granulomatous Disease.