PRIMARY HIV INFECTION

 Differential Diagnosis

Formerly considered to be similar to a mononucleosis-like viral syndrome, primary HIV infection does present with some unique features. Perhaps the most distinctive physical manifestation is the skin rash, which is rarely found in primary presentations of mononucleosis, toxoplasmosis, and cytomegalovirus infection. The rashes of rubella and roseola do not affect palms and soles. Other considerations in the differential diagnosis include hepatitis A or B, disseminated gonococcal infection, drug reactions, and secondary syphilis.

Emergency Department Treatment and Disposition

HIV testing is rarely performed in the ED owing to the difficulty of obtaining informed consent, lack of time for thorough counseling, and uncertain follow-up. Moreover, the diagnosis of acute HIV infection is difficult to make with standard serologic tests. Emergency physicians should take a careful history for HIV risk factors and should be cautious but honest in entertaining this diagnosis. Patients should be educated about safe sex and referred for further outpatient testing and evaluation. Prompt follow-up is critical, since immediate antiviral therapy is indicated for persons with acute HIV infection.

Clinical Pearls

1. Although historically HIV infection has been seen predominately in patients who belong to high-risk groups, the epidemiology is changing. When any sexually active patient presents to the ED with an acute, severe febrile illness, acute HIV infection should be included in the differential diagnosis.

2. Consider acute HIV infection as a potential etiology in patients with aseptic meningitis, pharyngitis, or a maculopapular rash.

3. Ensure proper follow-up for patients in whom the diagnosis of acute HIV infection is entertained.

 Differential Diagnosis

HIV-related candidal infections must be differentiated from a variety of other entities, depending on the site of infection:

Clinical Pearls

1. Popular one-dose oral treatments for oral or vaginal candidiasis are associated with a high rate of relapse in HIV patients.

2. Consider possible drug interactions when prescribing antifungal medications. For example, the absorption of ketoconazole is impaired by the simultaneous administration of antacids and cimetidine. Ketoconazole levels are also decreased in patients taking rifampin or isoniazid. Because of these drug interactions, many clinicians favor the use of fluconazole, since lack of gastric acid or the presence of food does not affect its absorption. Fluconazole does raise the serum levels of warfarin, rifabutin, or sulfonylureas.

3. Ensure follow-up in 3 to 5 days when treating empirically for presumptive esophageal candidiasis.

4. Oral candidiasis is a poor prognostic sign, predictive of progression to AIDS in the HIV-positive patient.

Antibody tests

HIV antibody tests are specifically designed for routine diagnostic testing of adults; these tests are inexpensive and extremely accurate.
[edit]Window period
Antibody tests may give false negative (no antibodies were detected despite the presence of HIV) results during the window period, an interval of three weeks to six months between the time of HIV infection and the production of measurable antibodies to HIV seroconversion. Most people develop detectable antibodies approximately 30 days after infection, although some seroconvert later. The vast majority of people (97%) have detectable antibodies by three months after HIV infection; a six-month window is extremely rare with modern antibody testing.[9] During the window period, an infected person can transmit HIV to others although their HIV infection may not be detectable with an antibody test. Antiretroviral therapy during the window period can delay the formation of antibodies and extend the window period beyond 12 months.[10] This was not the case with patients that underwent treatment with post-exposure prophylaxis (PEP). Those patients must take ELISA tests at various intervals after the usual 28 day course of treatment, sometimes extending outside of the conservative window period of 6 months. Antibody tests may also yield false negative results in patients with X-linked agammaglobulinemia; other diagnostic tests should be used in such patients.
Three instances of delayed HIV seroconversion occurring in health-care workers have been reported;[11] in these instances, the health-care workers[12] tested negative for HIV antibodies greater than 6 months postexposure but were seropositive within 12 months after the exposure.[13] DNA sequencing confirmed the source of infection in one instance. Two of the delayed seroconversions were associated with simultaneous exposure to hepatitis C virus (HCV). In one case, co-infection was associated with a rapidly fatal HCV disease course; however, it is not known whether HCV directly influences the risk for or course of HIV infection or is a marker for other exposure-related factors.
[edit]ELISA
The enzyme-linked immunosorbent assay (ELISA), or enzyme immunoassay (EIA), was the first screening test commonly employed for HIV. It has a high sensitivity.
In an ELISA test, a person’s serum is diluted 400-fold and applied to a plate to which HIV antigens have been attached. If antibodies to HIV are present in the serum, they may bind to these HIV antigens. The plate is then washed to remove all other components of the serum. A specially prepared "secondary antibody" — an antibody that binds to human antibodies — is then applied to the plate, followed by another wash. This secondary antibody is chemically linked in advance to an enzyme. Thus the plate will contain enzyme in proportion to the amount of secondary antibody bound to the plate. A substrate for the enzyme is applied, and catalysis by the enzyme leads to a change in color or fluorescence. ELISA results are reported as a number; the most controversial aspect of this test is determining the "cut-off" point between a positive and negative result.
[edit]Western blot

Western blot test results. The first two strips are a negative and a positive control, respectively. The others are actual tests.
Like the ELISA procedure, the western blot is an antibody detection test. However, unlike the ELISA method, the viral proteins are separated first and immobilized. In subsequent steps, the binding of serum antibodies to specific HIV proteins is visualized.
Specifically, cells that may be HIV-infected are opened and the proteins within are placed into a slab of gel, to which an electrical current is applied. Different proteins will move with different velocities in this field, depending on their size, while their electrical charge is leveled by a surfactant called sodium lauryl sulfate. Some commercially prepared Western blot test kits contain the HIV proteins already on a cellulose acetate strip. Once the proteins are well-separated, they are transferred to a membrane and the procedure continues similar to an ELISA: the person’s diluted serum is applied to the membrane and antibodies in the serum may attach to some of the HIV proteins. Antibodies that do not attach are washed away, and enzyme-linked antibodies with the capability to attach to the person’s antibodies determine to which HIV proteins the person has antibodies.
There are no universal criteria for interpreting the western blot test: The number of viral bands that must be present may vary. If no viral bands are detected, the result is negative. If at least one viral band for each of the GAG, POL, and ENV gene-product groups are present, the result is positive. The three-gene-product approach to western blot interpretation has not been adopted for public health or clinical practice. Tests in which less than the required number of viral bands are detected are reported as indeterminate: a person who has an indeterminate result should be retested, as later tests may be more conclusive. Almost all HIV-infected persons with indeterminate western blot results will develop a positive result when tested in one month; persistently indeterminate results over a period of six months suggests the results are not due to HIV infection. In a generally healthy low-risk population, indeterminate results on western blot occur on the order of 1 in 5,000 patients.[14]:However for those individuals that have had high-risk exposures to individuals where HIV-2 is most prevalent, Western Africa, an inconclusive western blot test may prove infection with HIV-2.[15]
The HIV proteins used in western blotting can be produced by recombinant DNA in a technique called recombinant immunoblot assay (RIBA).[16]
[edit]Rapid or point-of-care tests

A woman demonstrates the use of the OraQuick rapid HIV test
Rapid antibody tests are qualitative immunoassays intended for use as a point-of-care test to aid in the diagnosis of HIV infection. These tests should be used in conjunction with the clinical status, history, and risk factors of the person being tested. The positive predictive value of Rapid Antibody Tests in low-risk populations has not been evaluated. These tests should be used in appropriate multi-test algorithms designed for statistical validation of rapid HIV test results.
If no antibodies to HIV are detected, this does not mean the person has not been infected with HIV. It may take several months after HIV infection for the antibody response to reach detectable levels, during which time rapid testing for antibodies to HIV will not be indicative of true infection status. For most people, HIV antibodies reach a detectable level after two to six weeks.
Although these tests have high specificity, false positives do occur. Any positive test result should be confirmed by a lab using the western blot.
Home Access Express HIV-1 Test is the only FDA-approved home test: the patient collects a few blood drops from a fingerstick, and mails the sample to a laboratory; results and counseling are obtained over the phone. All results are anonymous and confirmed before they are released.
OraQuick is an antibody test that provides results in 20 minutes. The blood, plasma or oral fluid is mixed in a vial with developing solution, and the results are read from a sticklike testing device. Usually detects HIV 1 and HIV 2.[17]
Orasure is an HIV test that uses mucosal transudate from the tissues of cheeks and gums. It is an antibody test that first employs ELISA, then western blot.
Uni-Gold is a rapid HIV antibody test that provides results in 10–12 minutes. A drop of blood is placed on the device with developing solution. Uni-Gold is only FDA approved to test for HIV 1.
Clearview Complete HIV 1/2 and Clearview HIV 1/2 Stat-Pak are rapid tests for the detection of HIV 1 and HIV 2 antibodies in blood, serum, or plasma samples. Results are provided within 15 minutes.
There is also a urine test; it employs both the ELISA and the western blot techniques.
iDiagnostics Rapid HIV Test is, according only to their website, a non-FDA-approved home test. The company sells a blood test and a urine test produced by InTec PRODUCTS, INC. Similar to a home pregnancy test the patient collects a drop of blood/urine and drops the sample onto a cassette. Results are read visually in 15 minutes.[18][unreliable source?] The accuracy of this test has not been confirmed by the FDA, and it is not authorized for sale in the United States.[19]
The INSTI HIV-1/HIV-2* Rapid Antibody Test is a rapid in vitro qualitative test for the detection of antibodies to Human Immunodeficiency Virus Type 1 in human whole blood, serum or plasma. The test is intended for use by trained personnel in medical facilities, clinical laboratories, emergency care situations, and physicians’ offices as a screening assay capable of providing test results in less than 60 seconds. The assay is packaged as a kit containing INSTI Membrane Units, Sample Diluent, Color Developer and Clarifying Solution, and is available in point-of-care use packaging, or packaging suitable for laboratory use.[20]
Reveal HIV is a rapid in vitro qualitative test for the detection of antibodies to HIV in whole blood, serum or plasma. Reveal is among the fastest rapid HIV test available and it detects signs of early infection better than some other rapid tests.[21] Reveal HIV is approved in Canada, the United States, Europe, Africa, Asia, and South America.
[edit]Interpreting antibody tests
ELISA testing alone cannot be used to diagnose HIV, even if the test suggests a high probability that antibody to HIV-1 is present. In the United States, such ELISA results are not reported as "positive" unless confirmed by a Western Blot.
The ELISA antibody tests were developed to provide a high level of confidence that donated blood was NOT infected with HIV. It is therefore not possible to conclude that blood rejected for transfusion because of a positive ELISA antibody test is in fact infected with HIV. Sometimes, retesting the donor in several months will produce a negative ELISA antibody test. This is why a confirmatory Western Blot is always used before reporting a "positive" HIV test result.
Rare false positive results due to factors unrelated to HIV exposure are found more often with the ELISA test than with the Western Blot. False positives may be associated with medical conditions such as recent acute illnesses and allergies. A rash of false positive tests in the fall of 1991 was initially blamed on the influenza vaccines used during that flu season, but further investigation traced the cross-reactivity to several relatively non-specific test kits.[22] A false positive result does not indicate a condition of significant risk to health. When the ELISA test is combined with Western Blot, the rate of false positives is extremely low, and diagnostic accuracy is very high (see below).
HIV antibody tests are highly sensitive, meaning they react preferentially with HIV antibodies, but not all positive or inconclusive HIV ELISA tests mean the person is infected by HIV. Risk history, and clinical judgement should be included in the assessment, and a confirmation test (Western blot) should be administered. An individual with an inconclusive test should be re-tested at a later date.

Antigen tests

The p24 antigen test detects the presence of the p24 protein of HIV (also known as CA), the capsid protein of the virus. Monoclonal antibodies specific to the p24 protein are mixed with the person’s blood. Any p24 protein in the person’s blood will stick to the monoclonal antibody and an enzyme-linked antibody to the monoclonal antibodies to p24 causes a color change if p24 was present in the sample.
This test is no longer used routinely in the US [2] or the EU [3] to screen blood donations since the objective was to reduce the risk of false negatives in the window period. Nucleic acid testing (NAT) is more effective for this purpose, and p24 antigen testing is no longer indicated if a NAT test is performed. The p24 antigen test is not useful for general diagnostics, as it has very low sensitivity and only works during a certain time period after infection before the body produces antibodies to the p24 protein.
[edit]Nucleic acid-based tests (NAT)

Nucleic-acid-based tests amplify and detect one or more of several target sequences located in specific HIV genes, such as HIV-I GAG, HIV-II GAG, HIV-env, or the HIV-pol.[32][33] Since these tests are relatively expensive, the blood is screened by first pooling some 8-24 samples and testing these together; if the pool tests positive, each sample is retested individually. Although this results in a dramatic decrease in cost, the dilution of the virus in the pooled samples decreases the effective sensitivity of the test, lengthening the window period by 4 days (assuming a 20-fold dilution, ~20hr virus doubling time, detection limit 50 copies/ml, making limit of detection 1,000 copies/ml). Since 2001, donated blood in the United States has been screened with nucleic-acid-based tests, shortening the window period between infection and detectability of disease to a median of 17 days (95% CI, 13-28 Days, assumes pooling of samples).[34] A different version of this test is intended for use in conjunction with clinical presentation and other laboratory markers of disease progress for the management of HIV-1-infected patients.
In the RT-PCR test, viral RNA is extracted from the patient’s plasma and is treated with reverse transcriptase (RT) to convert the viral RNA into cDNA. The polymerase chain reaction (PCR) process is then applied, using two primers unique to the virus’s genome. After PCR amplification is complete, the resulting DNA products are hybridized to specific oligonucleotides bound to the vessel wall, and are then made visible with a probe bound to an enzyme. The amount of virus in the sample can be quantified with sufficient accuracy to detect threefold changes.
In the Quantiplex bDNA or branched DNA test, plasma is centrifugated to concentrate the virus, which is then opened to release its RNA. Special oligonucleotides that bind to viral RNA and to certain oligonucleotides bound to the wall of the vessel are added. In this way, viral RNA is fastened to the wall. Then new oligonucleotides that bind at several locations to this RNA are added, and other oligonucelotides that bind at several locations to those oligonucleotides. This is done to amplify the signal. Finally, oligonucleotides that bind to the last set of oligonucleotides and that are bound to an enzyme are added; the enzyme action causes a color reaction, which allows quantification of the viral RNA in the original sample. Monitoring the effects of antiretroviral therapy by serial measurements of plasma HIV-1 RNA with this test has been validated for patients with viral loads greater than 25,000 copies per milliliter.[35]
Further information: Viral load testing
[edit]Other tests used in HIV treatment

The CD4 T-cell count is not an HIV test, but rather a procedure where the number of CD4 T-cells in the blood is determined.
A CD4 count does not check for the presence of HIV. It is used to monitor immune system function in HIV-positive people. Declining CD4 T-cell counts are considered to be a marker of progression of HIV infection. A normal CD4 count can range from 500 cells/mm3 to 1000 cells/mm3. In HIV-positive people, AIDS is officially diagnosed when the count drops below 200 cells/μL or when certain opportunistic infections occur. This use of a CD4 count as an AIDS criterion was introduced in 1992; the value of 200 was chosen because it corresponded with a greatly increased likelihood of opportunistic infection. Lower CD4 counts in people with AIDS are indicators that prophylaxis against certain types of opportunistic infections should be instituted.
Low CD4 T-cell counts are associated with a variety of conditions, including many viral infections, bacterial infections, parasitic infections, sepsis, tuberculosis, coccidioidomycosis, burns, trauma, intravenous injections of foreign proteins, malnutrition, over-exercising, pregnancy, normal daily variation, psychological stress, and social isolation.[citation needed]
This test is also used occasionally to estimate immune system function for people whose CD4 T cells are impaired for reasons other than HIV infection, which include several blood diseases, several genetic disorders, and the side effects of many chemotherapy drugs.
In general, the lower the number of T cells the lower the immune system’s function will be. Normal CD4 counts are between 500 and 1500 CD4+ T cells/microliter, and the counts may fluctuate in healthy people, depending on recent infection status, nutrition, exercise, and other factors. Women tend to have somewhat lower counts than men.
[edit]Criticisms of HIV tests

[edit]Oral tests
As a result of an increase in false positive rates with rapid oral HIV testing in 2005, New York City’s Department of Health and Mental Hygiene added the option of testing finger-stick whole blood after any reactive result, before using a Western Blot test to confirm the positive result. Following a further increase of false positives in NYC DOHMH STD Clinics during the end of 2007 and beginning of 2008, their clinics opted to forgo further oral screenings, and instead reinsituted testing using finger-stick whole blood.[36] Despite the increase in false positives in NYC DOHMH, the CDC still continues to support the use of noninvasive oral fluid specimens due to their popularity in health clinics and convenience of use. The director of the HIV control program for public health at Seattle King county, reported OraQuick failed to spot at least 8 percent of 133 people found to be infected with a comparable diagnostic test.[37] Strategies implemented to determine quality control and false positive rates were implemented. It is to be understood that any reactive OraQuick test result is a preliminary positive result and will always require a confirmatory test, regardless of the mean of testing (venipuncture whole blood, fingerstick whole blood or oral mucosal transudate fluid) [38] Several other testing sites who did not experience a spike in false positive rates continue to use OraSure’s OraQuick HIV Anti-body Testing.[39][40]
[edit]AIDS denialism
HIV tests have been criticized by AIDS denialists (a fringe group that believes that HIV either does not exist or is harmless). The accuracy of serologic testing has been verified by isolation and culture of HIV and by detection of HIV RNA by PCR, which are widely accepted "gold standards" in microbiology.[26][27] While AIDS denialists focus on individual components of HIV testing, the combination of ELISA and Western blot used for the diagnosis of HIV is remarkably accurate, with very low false-positive and -negative rates as described above. The views of AIDS denialists are based on highly selective analysis of mostly outdated scientific papers; there is broad scientific consensus that HIV is the cause of AIDS.[41][42][43]
[edit]Fraudulent testing

There have been a number of cases of fraudulent tests being sold via mail order or the Internet to the general public. In 1997, a California man was indicted on mail fraud and wire charges for selling supposed home test kits. In 2004, the US Federal Trade Commission asked Federal Express and US Customs to confiscate shipments of the Discreet home HIV test kits, produced by Gregory Stephen Wong of Vancouver, BC. In February 2005, the US FDA issued a warning against using the rapid HIV test kits and other home use kits marketed by Globus Media of MontreaL CANADA

 Thrush is an infection caused by a yeast germ called Candida spp. The mouth is a common site where Candida spp. causes infection. Candidal infection in the mouth is called oral thrush. Other common sites for thrush to develop are the vagina, nappy area, and nail folds. (See separate leaflets called ‘Vaginal Thrush’, ‘Candidal Skin Infection’ and ‘Nappy Rash’ for more details about these other types of thrush.)

Who gets oral thrush?
Small numbers of Candida spp. commonly live on healthy skin and in a healthy mouth. They are usually harmless. Healthy people do not normally get oral thrush. However, certain situations or conditions may cause an overgrowth of Candida spp. which can lead to a bout of oral thrush. These include:

Being a baby. Oral thrush is quite common in young babies.
Wearing dentures, especially if they are not taken out at night, not kept clean, or do not fit well and rub on the gums.
A course of antibiotics. Antibiotics will kill harmless bacteria which live in the mouth. They do not kill Candida spp. which may multiply more easily if there are fewer bacteria around.
Excessive use of antibacterial mouthwash (for similar reasons to above).
Taking steroid tablets or inhalers.
Having a dry mouth due to a lack of saliva. This may occur as a side-effect from certain drugs (such as antidepressants, antipsychotics, chemotherapy), following radiotherapy to the head or neck, or as a symptom of Sjögren’s syndrome.
Having diabetes.
Having severe anaemia.
Lacking iron, folate or vitamin B12.
Having a poor immune system. For example, if you are taking medicines that suppress your immune system, if you have certain cancers, or if you have HIV/AIDS.
Being frail or in generally poor health.
Smoking. Smokers are more likely to develop oral thrush.
Oral thrush is not contagious. You cannot pass on oral thrush to other people.

What are the symptoms of oral thrush?
The classical symptom is white spots that develop in your mouth. The spots may join together to form larger spots called plaques. They may become yellow or grey. If you wipe off a spot, the underlying tissue may be red but it is not usually sore or painful.
Often there are no white spots. Areas in your mouth may just become red and sore. This more typically occurs if you get thrush after taking antibiotics or steroids.
Denture wearers may develop an area of persistent redness under a denture.
You may develop sore, cracked, red areas just outside your mouth. This mainly affects the angle where the upper and lower lips meet (angular stomatitis).
Some mild oral thrush infections are painless. However, sometimes oral thrush is quite sore and can make eating and drinking uncomfortable. Some babies with oral thrush may drool saliva, or not be able to feed properly because of soreness.
Taste can be affected in some people with oral thrush.
How is oral thrush diagnosed?
Your doctor will usually diagnose oral thrush by your typical symptoms and the typical appearance in your mouth. No investigations are usually needed to diagnose oral thrush.

However, your doctor may sometimes suggest a blood test to look for certain conditions that may make you more likely to develop oral thrush. For example, a blood test to see if you are lacking iron, B12 or folate.

If oral thrush does not respond to treatment (see below), your doctor may suggest that they take a swab from inside your mouth. The swab is then sent to the laboratory to be examined under a microscope. They can also try to grow the Candida spp. in the laboratory.

Occasionally, a biopsy is needed to confirm a diagnosis of oral thrush. A small sample is taken from the white patches inside your mouth and this can be examined under a microscope.

What is the treatment for oral thrush?
Locally applied treatment
For mild oral thrush, the usual treatment that is tried first is miconazole mouth gel for seven days. Sometimes a two-week course is needed. Nystatin drops are another option if miconazole gel cannot be used (for example, if you are known to be allergic to it).

Follow the instructions in the packet. Basically:

The gel or drops should be used after you have eaten or drunk.
Smear a small amount of gel on to the affected areas, with a clean finger, four times a day.
With the drops, you use a dropper to place the liquid inside your mouth on to the affected areas four times a day.
Ideally, you should not eat or drink for about 30 minutes after using either the gel or the drops. This helps to prevent the drug from being washed out of your mouth too soon.
Anti-thrush tablets
Tablets that contain a drug called fluconazole can also help to clear fungal and thrush infections from the body. Tablets tend to be used in more severe or serious cases. For example, for people with a poor immune system who develop extensive oral thrush. Tablets are usually prescribed for seven days and this will usually clear oral thrush.

Adjustment of other medication
If you are taking other medication that may have caused oral thrush, such as steroids or antibiotics, your doctor may need to change this medication or reduce the dose to help clear up your thrush.

Referral to a specialist
If the above measures do not help to clear your oral thrush infection, or if you have particularly severe infection or other health problems (for example, you are undergoing chemotherapy or are taking other drugs that weaken your immune system), your doctor may suggest that they refer you to (or ask the advice of) a specialist.

The specialist may suggest other treatments for oral thrush. For example, drugs such as itraconazole, ketoconazole or amphotericin.

Can oral thrush be prevented?
It may be possible to alter one or more of the situations mentioned above to help prevent further bouts of oral thrush. For example:

If you have diabetes – good control of your blood sugar level reduces the risk of thrush and other infections.
If you use steroid inhalers – having a good inhaler technique and using a spacer device may reduce the risk of thrush. Also, rinse your mouth after using the inhaler, to help remove any drug particles left in your mouth. Ask your doctor about reducing your dose of steroid in your inhaler to the lowest level needed to control your asthma.
If you wear dentures:
Leave your dentures out overnight, or for at least six hours daily. Constant wearing of dentures, and not taking them out at night, is thought to be one of the most common causes of oral thrush.
Clean and disinfect dentures daily. To clean, use soapy water and scrub the dentures with a soft nailbrush on the fitting surface – that is, the non-polished side. Then soak them in a disinfecting solution. The type of solution and the time they should be soaked for will be advised by your dentist. Rinse the dentures after disinfecting them, and then allow the dentures to air dry before wearing them again. Drying like this helps to kill any Candida spp. that might be stuck to the dentures.
Clean the inside of your mouth (where the dentures sit) with a soft brush.
See a dentist if the dentures do not fit well.
If you take medication which causes a dry mouth – take frequent sips of water. (See separate leaflet called ‘Dry Mouth’ for more details.)
Tips to prevent oral thrush in babies are included in the separate leaflet called ‘Thrush – Oral in Babies’.
If you are found to have anaemia or low levels of vitamin B12, folate or iron, treating this may help to prevent oral thrush in the future.
If you are a smoker, quitting smoking may help to prevent further bouts of oral thrush
Certain groups of people may be given anti-thrush tablets to help to prevent oral thrush. For example, people who are on medication to suppress their immune system or who are receiving chemotherapy for cancer.