Diagnosis of HIV/AIDS
Diagnostic Test list for HIV/AIDS:
The list of medical tests
mentioned in various sources as
used in the diagnosis of HIV/AIDS
includes:
- HIV antibody blood test - though the test sometimes cannot detect HIV for 6 months; sometimes not till 15 months for infected infants.
- Immune tests
- PAP smears - needed more often to check for cervical cancer in women.
HIV/AIDS Diagnosis: Book Excerpts
Tests and diagnosis discussion for HIV/AIDS:
Backgrounder - HIV Infection in Infants and Children: NIAID (Excerpt)
HIV infection is often
difficult to diagnose in very young children. Infected babies, especially
in the first few months of life, often appear normal and may exhibit no
telltale signs that would allow a definitive diagnosis of HIV infection.
Moreover, all children born to infected mothers have antibodies to HIV,
made by the mother's immune system, that cross the placenta to the baby's
bloodstream before birth and persist for up to 18 months. Because these
maternal antibodies reflect the mother's but not the infant's infection
status, the test is not useful in newborns or young infants.
In
recent years, investigators have demonstrated the utility of highly
accurate blood tests in diagnosing HIV infection in children 6 months of
age and younger. One laboratory technique called polymerase chain reaction
(PCR) can detect minute quantities of the virus in an infant's blood.
Another procedure allows physicians to culture a sample of an infant's
blood and test it for the presence of HIV.
Currently, PCR assays
or HIV culture techniques can identify at birth about one-third of infants
who are truly HIV-infected. With these techniques, approximately 90
percent of HIV-infected infants are identifiable by 2 months of age, and
95 percent by 3 months of age. One innovative new approach to both RNA and
DNA PCR testing uses dried blood spot specimens, which should make it much
simpler to gather and store specimens in field settings. (Source: excerpt from Backgrounder - HIV Infection in Infants and Children: NIAID)
HIV Infection and AIDS, An Overview, NIAID Fact Sheet: NIAID (Excerpt)
Because early HIV infection
often causes no symptoms, a doctor or other health care provider
usually can diagnose it by testing a person's blood for the presence
of antibodies (disease-fighting proteins) to HIV. HIV antibodies
generally do not reach detectable levels in the blood for one to
three months following infection. It may take the antibodies as long
as six months to be produced in quantities large enough to show up
in standard blood tests.
People exposed to the virus should
get an HIV test as soon as they are likely to develop antibodies to
the virus - within 6 weeks to 12 months after possible exposure to
the virus. By getting tested early, people with HIV infection can
discuss with a health care provider when they should start treatment
to help their immune systems combat HIV and help prevent the
emergence of certain opportunistic infections (see section on
treatment below). Early testing also alerts HIV-infected people to
avoid high-risk behaviors that could spread the virus to others.
Most health care providers can do HIV testing and will
usually offer counseling to the patient at the same time. Of course,
individuals can be tested anonymously at many sites if they are
concerned about confidentiality.
Health care providers
diagnose HIV infection by using two different types of antibody
tests, ELISA and Western Blot. If a person is highly likely to be
infected with HIV and yet both tests are negative, the health care
provider may request additional tests. The person also may be told
to repeat antibody testing at a later date, when antibodies to HIV
are more likely to have developed.
Babies born to mothers
infected with HIV may or may not be infected with the virus, but all
carry their mothers' antibodies to HIV for several months. If these
babies lack symptoms, a doctor cannot make a definitive diagnosis of
HIV infection using standard antibody tests until after 15 months of
age. By then, babies are unlikely to still carry their mothers'
antibodies and will have produced their own, if they are infected.
Health care experts are using new technologies to detect HIV itself
to more accurately determine HIV infection in infants between ages 3
months and 15 months. They are evaluating a number of blood tests to
determine if they can diagnose HIV infection in babies younger than
3 months.
(Source: excerpt from HIV Infection and AIDS, An Overview, NIAID Fact Sheet: NIAID)
Women and HIV-AIDS: NWHIC (Excerpt)
A window period is a recommended waiting period to receive an accurate
HIV test result. Generally, it is a six-week to six-month period from the
moment of your last unsafe sex encounter to the moment that you receive a
HIV screening. This is the time your body uses to create antibodies in the
blood stream, which signify exposure to HIV. This process is known as
seroconversion.
It is important when receiving an HIV test to ask what kind of test is
being used. Whenever someone is screened for HIV, two types of tests are
used. They are, 1) a reactive test, and 2) a confirmatory test. A reactive
HIV test indicates if HIV antibodies are in the blood (such as the Elisa
Test). A reactive test may give a false positive reading to anyone with
kidney or renal failure, to a woman that has had multiple pregnancies,
anyone receiving the influenza vaccine, or to anyone that has received
gamma globulin. When a reactive test has a negative result, that means no
HIV antibodies were detected. But in order to receive an accurate reading,
the CDC recommends you wait a specific window period: six weeks to six
months and either abstain from all sexual activity, or practice safe sex
in every sexual situation, and then get a confirmatory test, such as the
Western Blot Test.
A confirmatory test (such as the Western Blot) provides the HIV status
of a person. A positive test result on a confirmatory test means that the
person has been infected with HIV, has HIV antibodies in his or her blood,
and can infect others.
Being HIV positive does not mean that the person has acquired
immunodeficiency syndrome (AIDS) or that it is 100% guaranteed that the
person will get AIDS, though research has shown that it is likely to
happen.
(Source: excerpt from Women and HIV-AIDS: NWHIC)
Diagnosis of HIV/AIDS: medical news summaries:
The following medical news items
are relevant to diagnosis and misdiagnosis issues for HIV/AIDS:
Diagnostic Tests for HIV/AIDS: Online Medical Books
16 MEDICAL BOOKS ONLINE!
Review excerpts from medical books online, free, without registration,
for more information about diagnostis of HIV/AIDS.
Hearing Loss – Acquired:
Differential Diagnosis
(In A Page: Pediatric Signs and Symptoms)
Conductive (CHL)
-
Cerumen impaction
-
External auditory canal foreign body
-
Middle ear effusion (MEE)
–Frequently follows acute otitis media
-
Tympanic membrane (TM) perforation
–Usually due to trauma, chronic otitis media
-
Cholesteatoma
–Acquired cholesteatoma is accompanied by TM retraction or perforation
–Congenital cholesteatoma is usually over an intact TM
-
Ossicular erosion or fixation due to middle ear disease
-
Ossicular chain discontinuity (generally posttraumatic)
-
External auditory canal stenosis from chronic otitis externa
-
Middle ear tumor
–Paraganglioma (glomus tympanicum), facial neuroma, histiocytosis X, etc.
Sensorineural (SNHL)
-
Meningitis, especially bacterial
-
Viral, especially mumps
-
Autoimmune disease
–Vasculitis, scleroderma, Kawasaki disease
–Idiopathic
-
Acoustic trauma (noise-induced)
-
Ototoxic medications
–Aminoglycosides
–Diuretics (especially loop diuretics)
–Salicylates
–Cytotoxic (chemotherapeutic) agents, e.g., cisplatinum
-
Temporal bone fracture
–SNHL more likely with transverse than longitudinal fracture
-
Perilymphatic fistula (PLF)
–Hearing loss may be progressive or
fluctuating
- Cerebellopontine angle (CPA) tumor
–Vestibular schwannoma (a.k.a. acoustic neuroma, associated with type II neurofibromatosis), meningioma, etc.
–SNHL will be unilateral - Ménière disease
–Characterized by hearing loss, vertigo, tinnitus, sensation of aural fullness
Workup and Diagnosis
-
History
–Ask about risk factors for SNHL
-
Physical exam
–Check external auditory canal for patency
–Check TM for perforation or cholesteatoma
- Audiometric testing
–Classifies hearing loss as conductive, sensorineural, or mixed
–Quantifies the extent of the hearing loss for the full spectrum of sound frequencies
–If too young for ear-specific behavioral testing, obtain otoacoustic emissions and/or auditory brainstem response testing
–Tympanometry to objectively assess mobility (can help with diagnosis of MEE, ossicular discontinuity, and otosclerosis)
-
CT scan of temporal bones (fine cuts, axial and/or coronal, noncontrast) for CHL if cholesteatoma or trauma suspected
–Determines extent of bony erosion or involvement, and whether mastoid cavity is involved
-
MRI with gadolinium of internal auditory canals for
asymmetric SNHL
–Rule out CPA tumors
» READ BOOK EXCERPT ONLINE »
Source: In A Page: Pediatric Signs and Symptoms, 2007
Kaposi's sarcoma:
Diagnosis
(Professional Guide to Diseases (Eighth Edition))
CONFIRMING DIAGNOSIS Diagnosis is made following a tissue biopsy that identifies the lesion's type and stage. Then, a computed tomography scan may be performed to detect and evaluate possible metastasis. Endoscopy shows Kaposi's lesions. (See Laubenstein's stages in Kaposi's sarcoma.)
» READ BOOK EXCERPT ONLINE »
Source: Professional Guide to Diseases (Eighth Edition), 2005
Acquired immunodeficiency syndrome:
Diagnosis
(Professional Guide to Diseases (Eighth Edition))
CONFIRMING DIAGNOSIS Signs and symptoms may occur at any time after infection with HIV, but AIDS isn’t officially diagnosed until the patient’s CD4+ T-cell count falls below 200 cells/µl.
The most commonly performed tests, antibody tests, indicate HIV infection indirectly by revealing HIV antibodies. The recommended protocol requires initial screening of individuals and blood products with an enzyme-linked immunosorbent assay (ELISA). A positive ELISA should be repeated and then confirmed by an alternate method, usually the Western blot or an immunofluorescence assay. The radioimmunoprecipitation assay is considered more sensitive and specific than the Western blot, but because it requires radioactive materials, it’s a poor choice for routine screening. In addition, antibody testing isn’t reliable. Because people produce detectable levels of antibodies at different rates — a “window” varying from a few weeks to as long as 35 months in one documented case — an HIV-infected person can test negative for HIV antibodies. Antibody tests are also unreliable in neonates because transferred maternal antibodies persist for 6 to 10 months. To overcome these problems, direct tests are used, including antigen tests (p24 antigen), HIV cultures, nucleic acid probes of peripheral blood lymphocytes, and the polymerase chain reaction. (See Laboratory tests for diagnosing and tracking HIV and assessing immune status, page 396.)
Additional tests to support the diagnosis and help evaluate the severity of immunosuppression include CD4+ and CD8+ T-lymphocyte subset counts, erythrocyte sedimentation rate, complete blood cell count, serum beta2-microglobulin, p24 antigen, neopterin levels, and anergy testing. Because many opportunistic infections in AIDS patients are reactivations of previous infections, patients are also tested for associated neoplasms, infections, and STDs.
» READ BOOK EXCERPT ONLINE »
Source: Professional Guide to Diseases (Eighth Edition), 2005
Kaposi's sarcoma:
Diagnosis
(Handbook of Diseases)
The diagnosis is made following a tissue biopsy that identifies the lesion’s type and stage. Then a computed tomography scan may be performed to detect and evaluate possible metastasis.
» READ BOOK EXCERPT ONLINE »
Source: Handbook of Diseases, 2003
Human immunodeficiency virus infection:
Diagnosis
(Handbook of Diseases)
The CDC defines AIDS as an illness characterized by one or more “indicator” diseases coexisting with laboratory evidence of HIV infection and other possible causes of immunosuppression. The CDC’s current AIDS surveillance case definition requires laboratory confirmation of HIV infection in people who have a CD4+ T-cell count of 200 cells/µl or who have an associated clinical condition or disease.
Antibody tests
The most commonly performed tests, antibody tests indicate HIV infection indirectly by revealing HIV antibodies. The recommended protocol requires initial screening of individuals and blood products with an enzyme-linked immunosorbent assay (ELISA). A positive ELISA should be repeated and then confirmed by an alternate method, usually the Western blot or an immunofluorescence assay. However, antibody testing isn’t always reliable. Because the body takes a variable amount of time to produce a detectable level of antibodies, a “window” varying from a few weeks to as long as 35 months in one documented case allows an HIV-infected person to test negative for HIV antibodies.
Antibody tests are also unreliable in neonates because transferred maternal antibodies persist for 6 to 10 months. To overcome these problems, direct testing is performed to detect HIV. Direct tests include antigen tests (p24 antigen), HIV cultures, nucleic acid probes of peripheral blood lymphocytes with determination of HIV-1 ribonucleic acid levels, and the polymerase chain reaction.
Other tests
Additional tests to support the diagnosis and help evaluate the severity of immunosuppression include CD4+ and CD8+ T-lymphocyte subset counts, erythrocyte sedimentation rate, complete blood count, serum beta2-microglobulin, p24 antigen, neopterin levels, and anergy testing. Because many opportunistic infections in patients are reactivations of previous infections, patients are also tested for syphilis, hepatitis B, tuberculosis, toxoplasmosis and, in some areas, histoplasmosis.
» READ BOOK EXCERPT ONLINE »
Source: Handbook of Diseases, 2003
Chronic fatigue and immune dysfunction syndrome:
Diagnosis
(Handbook of Diseases)
The cause and nature of CFIDS are still unknown, and no single test unequivocally confirms its presence. Therefore, the diagnosis is based on the patient’s history and the CDC criteria. Because the CDC criteria are admittedly a working concept that may not include all forms of this disease and are based on symptoms that can result from other diseases, diagnosis is difficult and uncertain. Considerable overlap exists between CFIDS and fibromyalgia syndrome, with many patients having features of both.
» READ BOOK EXCERPT ONLINE »
Source: Handbook of Diseases, 2003
Community-acquired Pneumonia:
Diagnosis
(Pediatric Infectious Disease)
Basic Diagnostic Approach
The proportion of children with pneumonia who are diagnosed with a specific
etiology is low. Unlike adults, children usually do not produce adequate sputum
specimens for Gram stain and culture. Blood cultures have a yield of less than
10% in patients with bacterial pneumonia.
“Lung puncture” studies that are conducted in developing countries are obviously not met with
enthusiasm in general pediatric practices. Prospective studies that have
employed sensitive antibody tests and polymerase chain reaction techniques have
suggested that in up to 20% of pediatric community-acquired pneumonias, the
infection is
“mixed” (i.e., both
S. pneumoniae and M. pneumoniae or C. pneumoniae); in these cases, the primary pathogen is not clear. Authors of these studies
have also suggested that mixed infection with bacteria and respiratory viruses
is likely to be common as
well.
» READ BOOK EXCERPT ONLINE »
Source: Pediatric Infectious Disease, 2004
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