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| ==Overview==
| | #REDIRECT [[HIV infection pathophysiology#Stage 1: Primary HIV Infection]] |
| '''Acute HIV infection''' or '''primary HIV infection''' is the first stage of [[HIV]] infection. It occurs before the latency stage and the potential [[AIDS]] succeeding the latency stage.
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| ==Symptoms==
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| During this period (usually 2-4 weeks post-exposure) most individuals (80 to 90%) develop influenza or mononucleosis-like symptoms, most commonly [[fever]], [[lymphadenopathy]], [[pharyngitis]], generalized [[rash]] of [[maculopapular]] type, [[myalgia]], [[malaise]], mouth and esophagal sores, and may also include, but less commonly, [[headache]], [[nausea]] and [[vomiting]], enlarged liver/spleen, [[weight loss]], [[Candidiasis|thrush]], and neurological symptoms. Infected individuals may experience all, some, or none of these symptoms. The duration of symptoms varies, averaging 28 days and usually lasting at least a week.<ref name=Kahn>
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| {{cite journal
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| | author=Kahn, J. O. and Walker, B. D. | title=Acute Human Immunodeficiency Virus type 1 infection | journal=N. Engl. J. Med. | year=1998 | pages=33-39 | volume=331 | issue=1 | pmid=9647878
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| }}</ref> Because of the nonspecific nature of these symptoms, they are often not recognized as signs of HIV infection. Even if patients go to their doctors or a hospital, they will often be misdiagnosed as having one of the more common infectious diseases with the same symptoms. Consequently, these primary symptoms are not used to diagnose HIV infection as they do not develop in all cases and because many are caused by other more common diseases. However, recognizing the syndrome can be important because the patient is much more infectious during this period.
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| <ref name="pmid11187417">{{cite journal |author=Daar ES, Little S, Pitt J, ''et al'' |title=Diagnosis of primary HIV-1 infection. Los Angeles County Primary HIV Infection Recruitment Network |journal=Ann. Intern. Med. |volume=134 |issue=1 |pages=25–9 |year=2001 |pmid=11187417 |doi=}}</ref>
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| {| class="wikitable sortable"
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| |+ History and physical findings for primary HIV infection<ref name="pmid11187417">{{cite journal |author=Daar ES, Little S, Pitt J, ''et al'' |title=Diagnosis of primary HIV-1 infection. Los Angeles County Primary HIV Infection Recruitment Network |journal=Ann. Intern. Med. |volume=134 |issue=1 |pages=25–9 |year=2001 |pmid=11187417 |doi=}}</ref>
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| ! !! [[sensitivity (tests)|sensitivity]]!! [[specificity (tests)|specificity]]
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| | Fever || 88% || 50%
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| | Malaise || 73%|| 58%
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| | Myalgia || 60%|| 74%
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| | Rash || 58%|| 79%
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| | Headache|| 55%|| 56%
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| | Night sweats || 50%|| 68%
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| | Sore throat || 43%|| 51%
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| | Lymphadenopathy|| 38%|| 71%
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| | Arthralgia || 28%|| 87%
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| | Nasal congestion|| 18%|| 62%
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| |}
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| ==Cause==
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| It is a period of rapid viral replication that immediately follows the individual's exposure to HIV leading to an abundance of virus in the peripheral blood with levels of HIV commonly approaching several million viruses per mL.<ref name=Piatak> {{cite journal | author=Piatak, M., Jr, Saag, M. S., Yang, L. C., Clark, S. J., Kappes, J. C., Luk, K. C., Hahn, B. H., Shaw, G. M. and Lifson, J.D. | title=High levels of HIV-1 in plasma during all stages of infection determined by competitive PCR | journal=Science | year=1993 | pages=1749-1754 | volume=259 | issue=5102 | pmid=8096089 | doi=10.1126/science.8096089}}</ref> This response is accompanied by a marked drop in the numbers of circulating CD4<sup>+</sup> T cells. This acute viremia is associated in virtually all patients with the activation of [[cytotoxic T cell|CD8<sup>+</sup> T cells]], which kill HIV-infected cells, and subsequently with antibody production, or [[seroconversion]]. The CD8<sup>+</sup> T cell response is thought to be important in controlling virus levels, which peak and then decline, as the CD4<sup>+</sup> T cell counts rebound to around 800 cells per mL (the normal value is 1200 cells per mL ). A good CD8<sup>+</sup> T cell response has been linked to slower disease progression and a better prognosis, though it does not eliminate the virus.<ref name=Pantaleo1998>
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| {{cite journal
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| | author=Pantaleo G, Demarest JF, Schacker T, Vaccarezza M, Cohen OJ, Daucher M, Graziosi C, Schnittman SS, Quinn TC, Shaw GM, Perrin L, Tambussi G, Lazzarin A, Sekaly RP, Soudeyns H, Corey L, Fauci AS. | title=The qualitative nature of the primary immune response to HIV infection is a prognosticator of disease progression independent of the initial level of plasma viremia | journal=Proc Natl Acad Sci U S A. | year=1997 | pages=254-258 | volume=94 | issue=1 | pmid=8990195
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| }}</ref>
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| A strong immune defense reduces the number of viral particles in the blood stream, marking the end of the acute HIV infection and the start of the infection's [[incubation period|clinical latency]] stage, which, in turn, may be succeeded by true [[AIDS]].
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| ==References==
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| {{reflist|2}}
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| [[Category:HIV/AIDS]]
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