Question

1. What type of immunity does a vaccination during childhood provide? What is the advantage of receiving a vaccination? Discuss in two to three paragraphs natural vs. acquired immunity (active and passive) 2. What are opportunistic infections? Discuss in detail at least 5 of the opportunistic infections that develop in AIDS patients. Why do these infections occur in AIDS patients? 3. When a cancerous lesion is surgically removed from the breast, axillary lymph nodes are often removed as well. Why is removal of the lymph nodes thought to be important?

Answer 1

1. The vaccine induces artificial active immunity in a person. The vaccine contains antigen and it stimulates primary response against antigen in the body without causing symptoms of the disease

The response takes days/weeks to develop but may be long lasting—even lifelong.

The ability of an organism to resist the development of a disease is called Immunity or disease resistance.

Two general types of immunity are – natural immunity and acquired immunity.

Natural immunity

The inborn capacity of the person to resist a disease is called natural immunity.

It begins at birth and depends on genetic factors expressed as physiological, anatomical, and biochemical differences among living things.

Examples of natural immunity are acidic pH of the gastrointestinal and vaginal tracts, the lysozyme found in tears, saliva, and other body secretion, and interferon produced by body cells to protect against viruses.

Naturally acquired Active immunity:

When a person is exposed to a live pathogen and develops a primary a primary response, which leads to immunological memory.

Certain diseases cause lifelong immunityin people like chicken pox, measles etc.

Artificially acquired active immunity:

Artificially acquired active immunity can be induced by a vaccine, a substance that contains antigen. A vaccine stimulates a primary response against the antigen without causing symptoms of the disease.

Vaccines can be of different types like inactivated, live attenuated, toxoids or subunit vaccines.

Naturally acquired passive immunity[edit]

Naturally acquired passive immunity is the immunity passed from the mother to the fetus, during pregnancy. It is an antibody mediated immunity conveyed through placeta to the fetus by FcRn receptor on fetal cells. Ig G is the antibody which crosses placenta to the fetus. Ig A found in breast milk transferred to baby’s gut, protecting the baby against bacterial infections. Colostrum is the best naturally acquired passive immunity.

This immunity is not long lasting.

Artificially acquired passive immunity

The short-term immunization induced by the transfer of antibodies is called Artificially acquired passive immunity. This can be administered in several forms like human or animal blood plasma, as pooled human immunoglobulin for intravenous (IVIG) or intramuscular (IG) use, and in the form of monoclonal antibodies(MAb).

Eg: use of gammaglobulins in immunodeficiency.

2. Opportunistic infections are those infections which occurs in a person when the immunity is low. The immunity of the person may be low in some disease conditions like AIDS, Cancer etc, or when the person is taking medicines like steroids etc.

Common opportunistic infections associated with HIV include:

• cryptococcal meningitis

Cryptococcus is a common fungus found in soil and bird droppings and also growing in areas surrounding trees, and one variety particularly prefers eucalyptus trees. It causes meningitis when inhaled, an infection of the membranes around the brain and spinal cord.

Highly potent antifungal medications are used to initially treat cryptococcal meningitis, as are frequent spinal taps. These medications may include Amphotericin B, Fluconazole, Flucytosine and Itraconazole

• toxoplasmosis:

The neurotoxoplasmosis, or cerebral toxoplasmosis, is the infection of the brain by the protozoan Toxoplasma gondii.

It is caused by parasites in contaminated food and also be contracted from cat feces.

The risk for this infection is high when the CD4 cell count is below 100cells per micro liter and such people should receive preventive antibiotic therapy. They should avoid contact of micro organisms like cat feces.

The infection is treated with Trimethoprim-sulfamethoxazole.

• Pneumocystic pneumonia (PJP)

This is a fatal fungal pneumonia if it’s not diagnosed and treated early.

PJP is treated with antibiotics. The risk of a person with HIV developing PJP rises so high that preventive antibiotic therapy may be used if their CD4 count drops below 200 cells per microliter

• oesophageal candidiasis

Candidiasis is a group infections caused by Candida group of fungi. The infections include oral thrush and vaginitis. When the infection is found in Esophagus, bronchi, trachea or lungs, it hints at HIV infection.

Toxic antifungal agents are use for treatment . For vaginitis, Butoconazole, Clotrimazole , Miconazole are used.

In systemic infections, medicines like Flucanozole, Itraconazole, Posaconazole, Micafungin and Amphotericin B are used.

• Cryptosporidiosis

This is a parasitic infection caused by a tiny parasite that lives in the intestines of humans and animals. The people get this disease by drinking contaminated water and eating contaminated food.

This is a diarrheal illness , lasting longer and with severe symptoms in HIV patients.

Cryptosporidiosis is an unpleasant diarrheal illness for healthy people. However, for those who are HIV-positive, it can last longer and cause more severe symptoms.

A medication called nitazoxanide (Alinia) is normally prescribed to treat the disease.

The AIDS patients have a weak immune system with low CD 4 cell counts. So they are at very high risk for developing opportunistic infections.

3. The removal of axillary lymph nodes are important to prevent the lymphatic spread of the illness. The cells of cancer gets transported through the lymph nodes to other parts of the body, causing metastasis or generation of cancerous growth in parts other than where it originated.