HIV Transmission The HIV is often located within the cells especially in macrophages. HIV can survive for . days inside a cell but only about hours outside a cell. Routes of HIV transmission include unsafe sexual contact, blood-contaminated needles, organ transplants, blood transfusion and vertical transmission from HIV infected mother to child.
HIV is not transmitted by insects or by casual contact. reaction. Allergic reactions begin within few seconds after the contact with the allergen and last about half an hour. The common examples of allergens are mites in dust, pollens and some proteins in insect venom.
Hay fever and asthma are some common examples of allergy. Symptoms of allergic reactions include sneezing, watery eyes, running nose and difficulty in breathing. Allergy is a form of over active immune response mediated by IgE and mast cells. It can also be due to the release of chemicals like histamine and serotonin from the mast cells.
Anaphylaxis is the classical immediate hypersensitivity reaction. It is a sudden, systematic, severe and immediate hypersensitivity reaction occurring as a result of rapid generalized mast-cell degranulation.