Human Immunodeficiency Virus, Fungal and Protozoal Infections - Med Path

What are the most common affliction of humans and include the common cold, cold sores, hepatitis, human immunodeficiency virus (HIV), and several types of cancer.

Viral diseases

Viral Infection

Basic structure is the ______ (nucleic acid surrounded by the capsid).

Classified by the nucleic acid in the ______ (ribonucleic acid [RNA] or deoxyribonucleic acid [DNA]), whether it is single stranded (ss) or double stranded (ds), and whether it uses the enzyme reverse transcriptase for replication.

virion

What are intracellular parasites called

viruses

What does this refer to

Completely intracellular

• Attaches or binds to the host cell via protein receptors.

• Penetrates the host cell.

• Releases genetic information into the host cytoplasm.

  • RNA viruses enter the host nucleus.

    • Produce messenger RNA (mRNA) (new viral material).

    • May produce provirus DNA (retroviruses, HIV).

  • DNA viruses enter the host nucleus.

    • May integrate into the host DNA; may make mRNA.

Life cycle of viruses

What is this referring to

• Translation of mRNA results in the production of viral proteins.

• For enveloped viruses, new virions are released through budding.

• Viral DNA is integrated in the host cell and transmitted to daughter cells by mitosis

Life cycle of viruses

What viruses rapidly proliferate

Norovirus, rotovirus, Ebola, Marburg, hantavirus

______ are effective against many viruses

Interferons

What is sensitive to complement activation

viruses

What rarely produces toxins and thus infections tend to have mild symptoms

Viruses

What does this refer to

• Inhibition of DNA, RNA, or protein synthesis

• Disruption of lysosomal membranes

• Promotion of cell apoptosis

• Fusion of adjacent cells (giant cells)

• Transformation into cancer cells

• Alteration of antigenic properties (immune attacks normal cells)

Harmful effects of viral infection

________ is highly infectious

• Virions attach to respiratory epithelial cells and enter by endocytosis.

• May be fatal for the very young and the very old; it is seasonal.

• Surface proteins undergo change each year.

• Can have antigenic drift or mutation.

  • Mutation of genes that express surface molecules

• Can have antigenic shift.

  • Recombination into a new virus from two different species

Influenza

What is caused by the human immunodeficiency virus (HIV).

• Depletes the body’s T helper (Th) cells.

• Is susceptible to life-threatening infections and cancer.

Acquired immunodeficiency syndrome (AIDS)

What is a

• Bloodborne pathogen is present in body fluids (e.g., blood, vaginal fluid, semen, breast milk).

• Routes of transmission

  • Blood or blood products, intravenous drug use, heterosexual and homosexual activity, and maternal-child transmission before or during birth

Human Immunodeficiency Virus and Acquired Immunodeficiency Syndrome

Both types if HIV (HIV-1 and HIV-2) are

retroviruses

What does this refer to

• Stores genetic material on two copies of RNA rather than the usual dsDNA.

• Carries an enzyme, reverse transcriptase, that creates a dsDNA version of the virus.

• Integrase inserts new DNA into the infected cell’s genetic material.

  • May be dormant: No problems develop.

  • May activate: Many problems develop; new DNA becomes part of the cell’s genetic material and accelerates apoptosis and shedding of infectious HIV.

RNA virus (retrovirus)

What does this refer to

• Serologically negative, serologically positive but asymptomatic, early stages of HIV, or AIDS

• Window period: Infectious but asymptomatic

• Fatigue, headache, muscle aches, fever

• May be asymptomatic for years.

Clinical manifestations of Human Immunodeficiency Virus and Acquired Immunodeficiency Syndrome

What is the following refer to

• Uses various clinical conditions and laboratory tests.

• Atypical or opportunistic infections and/or cancer

• CD4+ T-cell numbers are at or below 200 cells/µL (depending on age).

Diagnosis of Human Immunodeficiency Virus and Acquired Immunodeficiency Syndrome

What does this refer to

• Illnesses that indicate progression from HIV to AIDs

• Occur when CD4 count < 200 cells/mm³ or presence of specific conditions

AIDS-Defining Illness

What does this refer to

• Opportunistic infections: Pneumocystis pneumonia (PCP), candidiasis, TB, toxoplasmosis

• Cancers: Kaposi’s sarcoma, non-Hodgkin lymphoma, invasive cervical cancer

• Other: Cytomegalovirus (CMV) retinitis, Mycobacterium avium complex (MAC)

Common examples of AIDS-Defining Illness

What does this refer to

• Signal advanced immune suppression

• Guide diagnosis and treatment

• Preventable with antiretroviral therapy (ART)

Importance of AIDS-Defining Illness

What is the treatment for Human Immunodeficiency Virus and Acquired Immunodeficiency Syndrome

Antiretroviral therapy (ART)

• Three or more drugs: Usually two drugs target reverse transcriptase (inhibits reverse transcriptase) and one is from a different class of drugs.

• Does not cure; rather, it slows progression.

How do you prevent Human Immunodeficiency Virus and Acquired Immunodeficiency Syndrome

Not possible, there is no proven vaccine

A person who is HIV positive is hospitalized with pneumonia caused by Pneumocystis jirovecii. The physician assistant understands that this development indicates the person

1. has adequate amounts of Th cells.

2. is serologically positive for asymptomatic HIV disease.

3. is in the early stages of HIV disease.

4. has progressed from HIV to AIDS.

has progressed from HIV to AIDS.

What does this refer to

• Large microorganisms with thick, rigid cell walls

• Mold, yeast, dimorphic

• Disease caused by fungi: Mycosis

• Disease transmitted by inhalation or contamination of wounds

• Dermatophytes if infections invade skin, hair, or nails

Fungal infection

What does this refer to

• Systemic infection is usually from immunosuppression.

• Pneumocystis carinii was reclassified as a fungus and renamed P. jirovecii.

• Adapt to the host environment.

  • Wide temperature variations, low oxygen, alkaline pH

• Suppress the immune defenses.

Fungal infection

How does fungi survive phagocytosis

• by replicating into the phagosome or inhibiting lysosomal enzyme

• Will encapsulate, alter antigen expression, and stimulate immunosuppressive cytokines to resist phagocytosis.

• Tissue damage is from fungal enzymes and indirectly from inflammation.

______ Is the most common fungal infection.

• Resides in skin, gastrointestinal tract, mouth, and vagina.

• Local defense mechanisms and microbiome produce antifungal agents.

• Remains localized if the immune system is intact; if the immune system is compromised, then the infection can become systemic.

Candida Albicans

What does this refer to

• Toxoplasma gondii

• Trichomonas vaginalis

Common parasitic infections

What does this refer to

• _____ range from unicellular protozoa to large worms.

  • Parasitic worms (helminths)

  • Intestinal and tissue nematodes (e.g., hookworm, roundworm)

  • Flatworms (e.g., liver fluke, lung fluke, tapeworm)

Parasites

What parasitic worm can cause infection in the intestines or the body

Roundworms

What parasitic worm generally infects the bile ducts, liver, or blood

Flukes

What parasitic worm infects the intestines

Tapeworms

What parasitic worm mainly infects animals, rarely can infect humans

Thorny-headed worms

What does this refer to

• Rarely transmitted from human to human; are transmitted mainly through vectors.

• Malaria (Falciparum sp) by mosquito bites

• Sleeping sickness (Trypanosoma cruzei) by the tsetse fly in Africa, Chagas disease by the triatomine or kissing bug in America

• Leishmania spp. by sand fleas

• Others found in contaminated water or food (e.g., Giardia lamblia).

Parasitic infections

What does this refer to

• GI tract

• Vagina (STI)

• Skin (bites)

Extracellular component of parasitic infection

What does this refer to

• Ingestion of contaminated food/water

• Bites from insect vectors

Intracellular component of parasitic infection

Tissue damage caused by parasites is secondary to…..

the release of enzymes that destroy surrounding extracellular matrix and tissue

What does this refer to

• Individual’s immune/inflammatory response

• Physical loss in tissue or organ

• Immune hypersensitivity reaction

Response to parasitic infection

What does this refer to

• Antibody-mediated complement activation

  • Effective against several parasites

• Pathogen-specific and nonspecific immune suppression

  • Pathogen tolerance

Parasite blocking of immune response

What does this refer to

______________ is the most common infection worldwide.

• Is transmitted through the bite of an infected Anopheles mosquito.

• Parasite enters the bloodstream, survives in the liver, and invades the parenchymal cells.

• After several rounds of division, the liver cell ruptures, and thousands of parasites enter the blood, infecting the red blood cells.

Malaria

Which information is correct regarding parasitic infections?

• These types of infections attach through pili (fimbriae).

• C. albicans is an example of a parasitic infection.

• Parasitic infections are transmitted from human to human.

• Malaria is a common parasitic infection.

Malaria is a common parasitic infection