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Epidemiology of HIV-2 infection
in the U.S, 1996-2006
Lata Kumar MS, MPH
Richard Selik MD
Division of HIV/AIDS Prevention
National Center for HIV/AIDS, Viral Hepatitis, STD and TB Prevention
Centers for Disease Control and Prevention
2007 HIV Diagnostics Conference, Dec 5-7, 2007
The findings and conclusions in this presentation are those of the authors and do not necessarily
represent the views of the Centers for Disease Control and Prevention.
Outline
• Background
• Methods
– Diagnostic criteria
• Results
• Discussion
• Conclusion
• Recommendation
Background
Background
– HIV-2 first isolated 1986 – West Africa
– HIV-1 and HIV-2 - 60-70% homologous
HIV Groups and Subtypes
HIV
HIV-1
Group O
Group N
HIV-2
Group M *
Subtypes A - K
Subtypes A-G
*HIV-1, subtype B most common in U.S.
HIV-2 Prevalence Highest in
West Africa
Ivory Coast
Guinea Bissau
The Gambia
Guinea
Senegal
Other Countries Reporting
HIV-2 Infections
< 1% HIV-2
HIV-2 – Transmission
Same modes of transmission as HIV-1
*
‘
Male-to-male sexual contact (MSM)
Injection drug use (IDU)
Both MSM and IDU (MSM/IDU)
High-risk heterosexual contact* (HRH)
Other '
Heterosexual contact with a person known to have or to be at high risk for HIV infection
Includes persons that acquired HIV due to hemophilia or a blood transfusion and person
whose risk factor was not reported or identified
HIV-2 – Clinical Aspects
- Less transmissible
- Progresses more slowly to AIDS
- Lower mortality
Source
Marlink R., “Lessons learned from the second AIDS
Virus, HIV-2”, AIDS 10: 689-699. 1996
HIV-2 – Risk Factors
•
Native of West Africa
•
Sexual contact or needle sharing with
- a person from this endemic region
- a person with known HIV-2 infection
•
Children of women with or at-risk for HIV-2
Methods
HIV-2 – Surveillance Methods
Laboratory component:
Identify and confirm infections
Interview component:
Determine exposures, risk factors, and
country of origin
Data Source
CDC maintains supplemental database for
reports on HIV-2 infection to ensure
completeness of reporting
Diagnostic Criteria
Figure 1. Centers for Disease Control/Food and Drug
Administration testing algorithm for use with combination
HIV-1/HIV-2* enzyme immunoassays(EIAs)
HIV-1/HIV-2 EIA
HIV-1 Western Blot
Positive
@
Indeterminate
Negative
Report as HIV positive ^
HIV-2 EIA
Repeatedly Reactive
HIV-2 Supplemental Test
( e.g., Western blot)
Positive
Negative
Indeterminate
* HIV- human immunodeficiency virus
@ An Immunofluoresence assay (IFA) for HIV-1 antibodies has recently been licensed by the Food and Drug
Administration and can be used instead of Western blot. Positive and negative IFA results should be interpreted in the same
manner as similar results from Western blot tests.
An indeterminate IFA should first be tested by Western blot and then as indicated by the Western blot results.
^ Perform HIV-2 EIA only if there is an identified risk factor for HIV-2 infection
HIV-2 – Laboratory Diagnosis
1.
Screening HIV-1/2 ( EIA)
2.
Perform HIV-1 Western Blot
- Rule out HIV-1 first *
3.
Bio-Rad HIV-1/ HIV-2 Multispot
4. Detect/Confirm HIV-2 antibodies
- HIV-2 Western blot
- PCR for unique sequences
* HIV-2
not FDA licensed
antibodies can react with bands on HIV-1
Results
Distribution of HIV-2 cases in the U.S
by Country of Birth, 1996-2006 (N=68)
Other Countries
2%
India
India
12%
12%
Other
Africa 7%
East
EastAfrica
Africa
11%11%
West Africa
West
Africa
66%
66%
Distribution of HIV-2 cases among
the different regions in the U.S,
1996-2006
US region
Number of cases
Midwest
26 (38%)
South
12 (18%)
Northeast
12 (18%)
West
8 (12%)
Total
68
Disease category of HIV-2 cases at
diagnosis, United States, 1996-2006
Among the 68 reported
– 19 cases had AIDS
– 29 cases did not have AIDS
– 20 cases did not have sufficient information to
know status
Distribution of HIV-2 cases by
Race/Ethnicity, United States,
1996-2006
Race/Ethnicity
Number of cases
Blacks
53 (77%)
Asian /Pacific Islanders
Other/unknown
8 (12%)
7 ( 10%)
Total
68
Discussion
Discussion
• HIV-2 infection continues to be of low
prevalence in the U.S
• Majority of the cases reported are from
persons of West African origin
• Diagnosis of HIV-2 continues to be a
challenge – absence of FDA approved
confirmatory test
Limitation
• Incomplete reporting since not all states
have reported HIV-2 consistently to CDC?
• The total cases here may be an under
estimation of the true cases
Conclusion
• Although HIV-2 continues to be of low
prevalence in the US, monitoring the type of
HIV infection needs to continue in the U.S
– Since antiretroviral treatment (ARV) is different for
HIV-2 infection
– Misdiagnosis of HIV-2 to be HIV-1 due to crossreactivity
Recommendation
When HIV-2 is suspected, the following steps
should be followed :
• Send specimens to CDC laboratory for
confirmation
• Contact CDC coordinator for “Cases of Public
Health Importance” (COPHI)
Questions ?
Lata Kumar
[email protected]
Tel: 404-639-3893