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HIV-1 is the predominant subtype worldwide and is the cause of AIDS.
HIV-2 causes a similar immune syndrome,
but exists primarily in western Africa and is infrequent
in the United States, but its incidence is growing
Immunologic abnormalities : lymphopenia,
qualitative CD4+ T-cell function defects,
and autoimmune phenomena.
Defects in cellular immunity ultimately result in a
variety of opportunistic infections and neoplasms.
感染性疾病檢查 Infectious disease (CD4/CD8)
HIV Ag/Ab combo test (Screening test) - p24 (第四代抗原、抗體檢驗方式)
Human immunodeficiency virus type 1
主要感染 CD4 (Th cells)
只是被 HIV 感染, 還不是 AIDS
AIDS 條件是 HIV 感染且
CD4 < 200 /µl or
AIDS defining conditions
(Opportunistic infection, Kaposi sarcoma, Lymphoma...)
Stage 1 : Acute retroviral syndrome
2 to 4 weeks after infection
Nonspecific flulike or mononucleosis-like syndrome :
fever (>90%), fatigue (70-90%), pharyngitis (>70%), rash (40% to 80%),
headache (30% to 70%), lymphadenopathy (40-70%)
Typically occur within 1 month of becoming infected,
may last for 2 to 10 weeks,
Seroconversion and detectable antibody response to HIV
usually occur 3 to 8 weeks after infection
一開始感染 3 - 6 w 是 急性期
病毒暴增出現在在血液, 淋巴
通常只出現感冒症狀 : fever, rash, sore throat, muscle pain
2 - 4w 後症狀緩解
Stage 1 : Clinical latency, HIV inactivity
Possible persistent generalized lymphadenopathy
Median incubation time from exposure to AIDS is estimated at 10 years for adults
Steady state of HIV replication
As CD4 count begins to drop and viral load starts to rise,
patients begin to develop symptomatic infection characterized by
conditions that are more common and more severe
in the presence of HIV infection, but are not AIDS-indicator conditions.
These include thrush, persistent vulvovaginal candidiasis,
peripheral neuropathy, cervical dysplasia,
recurrent herpes zoster, and idiopathic thrombocytopenic purpura
Latency 潛伏期 : 7-10年
HIV 血中少
無症狀
頂多身上淋巴結腫大
此階段病人免疫力都還堪用
Progression :
免疫力開始潰堤
血中 HIV 高高高
Constitutional 全身性症狀開始出現 fatigue, weight loss, fever, diarrhea
Stage 3
CD cell counts < 200 cells/mm3
or occurrence of one of any opportunistic infections or AIDS-defining illness
- Screen : ELISA ( Sen > 99% )
- Confirm : Western blot ( Spe > 99% )
* CD4 count : 600 – 1500 /µl in normal
Textbook :
Mean times from transmission to detection are shortest for
- Viral load (17 days)
- p24 antigen (22 days)
- Enzyme-linked immunosorbent assay positivity (ELISA) (25 days)
- Western blot positivity (31 days)
The most commonly used testing method for HIV is detection of antibodies to the virus.
Automated testing for antibody to HIV-1 and HIV-2 simultaneously with detection of
HIV-1 p24 antigen, permitting detection of acute infections
-> Negative, no further testing occurs,
and the patient is counseled that tested negative
-> Positive results, follow-up testing differentiates HIV-1 and HIV-2
A total lymphocyte count < 1700 cells/mm3
had a sensitivity of 95% for a CD4 count of < 200 cells/mm3
現在大多數醫院是測 P24 抗原和抗體
同時驗 HIV 1 + 2
稱為 Combo test
(和過去的 ELISA 不同)
感染到 HIV 到可以用 PCR 測出 Viral load 的期間稱為 Eclipse stage
Plasma virus levels 開始上升
在感染後 21–28 天達到 peak
之後緩緩下降
* Fiebig stages I–VI 的不同分期可以用不同方法測到 HIV
- Viral RNA measured by PCR
- p24 and p31 viral antigens measured by ELISA
- HIV-1-specific antibody detected by ELISA
- HIV-1-specific antibodies detected by Western blot
Acute HIV infection 要如何正確診斷呢？
平常使用的篩檢工具是 ELISA 通常要 25 天 才會抓得到
新的第四代篩檢工具 CMIA (Combo test)
針對 p-24 protein, 同時偵測 Antibody + Antigen
但也要 22天 才會抓到
大部分人會記 空窗期3-6週, 如果第一次ELISA negative, 要 3 個月之後再做一次
Western blot 常常被拿來當確診工具
但是如果時間不夠長
他還是可能會 Negative
如果病人正在 Acute HIV syndrome
只能夠用 HIV PCR 或者直接測 HIV virus load 來檢測
大概可以記 clinical acute infection 症狀出現在 3-6w 然後持續 2- 4w
所以是感染後大約 20 天 - 40 天開始有急性症狀
持續到感染後 35 - 70 天急性期結束
PCR 大約感染後 10 天 可以測到病毒量
ELISA 大約感染後 25 天 可以 +
Wester blot 確診要 100 天 才 +
所以記 ELISA 空窗期約 3 周
急性 HIV 感染 當然 Western blot 不會 +
醫學會 :
RNA 10 天
P24 Ag 兩週
Western blot 一個月才能偵測抗體
近三年新診斷 HIV 人數皆下降
新診斷 HIV 7 天內都要接受治療
不論 CD4 數值
Screening test positive or 高度懷疑
就該驗 viral load, 不要靠 western blot
無症狀期, Acute viral hepatitis, STD : 要考慮 HIV
TB, HCV, Cryptococcal toxoplasmosis : 都是反射驗 HIV
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