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INFEcnOU5 DISEASES 631
Transmission of these organisms is usually through the ingestion of
contaminated food, water, or both or by direct and indirect fecal-oral
transmission.
The primary manifestations of any form of gastroenteritis are
crampy abdominal pain, nausea, and diarrhea, all of which vary in
severity and durarion according to the type of infection. Gastroenteritis is generally a self-limiting infection, with resolution occurring in 3-4 days. However, patients in the hospital setting with reduced immunity can have longer periods of recovery, with dehydration being a primary concern.ll.JI.44
Management of acute gastroenteritis may consist of the
foliowing'2.JL
• Anti-infective agents
• i.v. fluid and electrolyte replacement
• Antiemetic agents (if nausea and vomiting occur)
Clinical Tip
Strict cOntact and enteric precautions should be observed
with patients who have a diagnosis of C. dif{icile infection.
Immune System Infections
Human Immunodeficiency Vints /"fection
Two types of HN exist: HN-I and HIV-2, with HN-J being the more
prevalent and the one discussed here. It is a retrovirus, occurring in
pandemic proportions, that primarily affects the function of the
immune system. Eventually, howeve� all systems of the body become
affected directly, such as the immune system, or indirectly, as in the cardiac system, or through both methods, as occurs in the nervous system.
The virus is transmirccd in blood, semen, vaginal secretions, and
breast milk through sexual, perinatal, and blood or blood product
contact. Proteins on the surface of the virus attach to CD4+ receptors, found primarily on T4 lymphocytes·' Other types of cells found to house the virus include monocytes, macrophages, uterine
cervical cells, epithelial cells of the gastrointestinal tract, and
microglia cells."
632 AClJfE CARE HANDBOOK FOR PHYSICAL THERAPISTS
On entering the cell, the viral and cellular DNA combine, making
the virus a part of the cell. The exact pathogenesis of cellular destruction caused by HIV is not completely understood, and several methods of destruction may be entailed. It is known that immediately after initial infection, HIV enters a latent period, or asymptomatic stage, in
which viral replication is minimal, but CD4' T cell counts begin to
decline.45 Continued reduction results in decreasing immunity, eventually leading to symptomatic HN, in which diseases associated with the virus begin to appear.4S This eventually leads to the onset of AIDS,
which the CDC defines as occurring when the CD4' T-Iymphocyte
COunt falls below 200 cells/Ill (normal, 650-1,200 cellS/ill) or below
14%, when 1 of 26 specific AIDS defining disorders is contracted, or
a combination of these factors.46
Five laboratory tests are available to detect HIV infection47•48:
1.
Enzyme-linked immunosorbent assay or enzyme immunoas-
say test. This procedure tests for the presence of antibodies [0 HN
proteins in the patient's serum. A sample of the patient's blood is
exposed to H1V antigens in the test reagent. If HIV antibodies are
identified, it is inferred that the virus is present within the patient.
2.
Western blot test. This test detects the presence of antibod-
ies in the blood to twO types of HIV viral proteins and is, therefore,
a more specific HIV test. It is an expensive test to perform and is
used as a confirmatory tool for a positive enzyme-linked immunosorbent assay test.
3.
Immunofluorescence assay. In this test, the patient's blood
is diluted and placed on a slide containing HIV antigens. The slide
is then treated with anti-human globulin mixed with a fluorescent
dye that will bind to antigen-antibody complexes. If a fluorescence
is seen when the specimen is placed under a microscope, then HIV
antibodies are present in the patient'S blood.
4.
p24 Antigen assay. This test analyzes blood cells for the
presence of the p24 antigen located on HN virions. It can be used
to diagnose acute infection, to screen blood for HIV antigens, to
determine HIV infection in difficult diagnostic cases, or to evaluate
the treatment effects of antiviral agents.
5.
Polymerase chain reaction for HIV nucleic acid. This highly
specific and extremely sensitive test detects the viral DNA molecule
INFECfIOUS DISEASES
633
in lymphocyte nuclei by amplifying the viral DNA. It is used to
deteer HfY in neonates and when antibody tests arc inconclusive.
Once HIV has been detected, it can be classified in a number of
ways. The Walter Reed staging system has six categories grouped
according to the quantity of helper T cells and characteristic signs,
such as the presence of an HIV antigen or antibody.·9 However, a
more commonly used classification system was devised by the CDC
and was last updated in 1993. In this system, infection is divided into
three categories, depending on CD4' T-Iymphocyte counts:
I.
Category I consists of CD4' T-Iymphocyte counts greater
than or equal to 500 cellsl�1.
2.
Category 2 consists of counts ranging between 200 and
499 cells/�1.
3.
Category 3 contains cell counts less than 200 cells/�1.
These groups are then subdivided intO A, B, and C, according to the
presence of specific diseases.4•
Advancement in the medical treatment of HfV, in the form of antiretroviral therapy, has recently been made. This therapy consists of three types of medications'9:
1.
Nucleoside analog reverse transcriptase inhibitOrs, otherwise
known as nucleoside analogs. These include zidovlldine, didanosine,
zalcitabine, stavlldine, and lamivudine.
2.
Protease inhibitOrs, including saqllinavir, indinavir, rironavir,
and nelfinavir.
3.
Non-nucleoside reverse transcriprase inhibitors, including
delavirdine and nevi rapine.
Each of these therapies assists in limiting HIV progression by helping to prevent viral replication. This prevention is furrher increased when the drugs are used in combination in a treatment technique
termed highly active alltiretroviral therapy or HAART.'9
As HIV progresses and immunity decreases, the risk for and severity of infections not normally seen in healthy immune systems increase. These opporruilistic infections, combined with disorders
634
AClITE CARE HANDBOOK FOR I'HYSICAL THERAI'ISTS
that result directly from the virus, often result in multiple diagnoses
and medically complex patients. These manifestations of HIV can
affect every system of the body and present with a wide array of signs
and symptoms, many of which are appropriate for physical therapy
intervention. Table 10-5 lists common manifestations and com plicarions of HIV and AIDS and the medications generally used in their management.
Disorders affecting rhe nervous sysrem include HIV-associared
dementia complex, progressive multi focal leukoencephalopathy, primary central nervous system lymphoma, toxoplasmosis, and neuropathies. These manifestations may cause paresis, decreased sensation, ataxia, aphagia, spasticity, altered mental status, and
visual deficits 50 In the pulmonary system, TB, cytomegalovirus
(CMV), and pneumonia can result in cough, dyspnea, sputum production, and wheezing.51 In the cardiac system, cardiomyopathy, arrhythmias, and congestive heart failure can cause chest pain,
dyspnea, tachycardia, tachypnea, hypotension, fatigue, peripheral
edema, syncope, dizziness, and palpitations.52
Physical therapy intervention can assist in minimizing the effect of
these deficits on functional ability, therefore helping to maximize the
independence and quality of life of the individual. However, the course
of rehabilitation in HIV-affected individuals can often be difficult
owing to coinciding opportunistic infections, an often-rapid downhill
disease course, low energy states, and frequent hospitalizations.
Mononucleosis
Mononucleosis is an acute viral disease that has been primarily linked
to the Epstein-Barr virus and less commonly to CMV. Mononucleosis
is transmitted generally through saliva from symptomatic or asymptomatic carriers (the Epstein-Barr virus can remain infective for 18