MDH HIV Subtype and Drug Resistance Surveillance
The Minnesota Department of Health (MDH), STD, HIV and TB Section and Public Health Laboratory have incorporated HIV drug resistance and subtype surveillance into routine HIV surveillance. This activity will allow MDH to describe and monitor the prevalence of HIV subtypes and drug resistance among individuals newly diagnosed with HIV in Minnesota. Minnesota's disease reporting rules were revised in 2005 to require submission of clinical materials from newly diagnosed cases of HIV infection. Starting September 1, 2005 HIV drug resistance testing and viral subtype determination will be conducted on all eligible specimens.
Of the two types of HIV (HIV-1 and HIV-2), HIV-1 is responsible for the global pandemic and exhibits extensive genetic diversity. HIV Type 1, subtype B is most prevalent in North America, western Europe and Australia and subtypes A, C, D and A/G are most common in Africa and other parts of the world.
As a result of travel and migration, the HIV epidemic in Minnesota has become more diverse. Data from pilot HIV subtype surveillance indicated at least 7 non-B HIV-1 subtypes are present in the state; presently variant subtypes appear to be limited to persons born outside the U.S. Further information about HIV-1 subtypes in Minnesota may be found in the July 1 issue of the Journal of Infectious Diseases (Free Access).
HIV genetic diversity is also exhibited in the form of mutations that confer resistance to antiretroviral (ARV) drugs. Because HIV has both a high mutation and replication rate, ARV drug resistance is a common response to the selective pressure of HIV drugs and complicates treatment. Drug resistance testing is one tool clinicians use to select an appropriate ARV drug regimen for patients. This testing is routinely employed before selecting a first regimen or whenever switching ARV drug regimens. However, there is disagreement about the value in obtaining a drug resistance test at initial exam. Current treatment guidelines recommend drug resistance testing at initial exam if the prevalence of primary drug resistance (i.e. HIV drug resistance acquired at transmission rather than in response to ARV drugs) in the area is 5% or greater. Unfortunately, little is known about the frequency of transmitted HIV drug resistance in the U.S. and even less about the frequency in Minnesota.
HIV subtype and drug resistance surveillance will help address the public
health and clinical challenges presented by the extensive genetic variation
HIV-1 possesses. Knowledge about the prevalence of different HIV subtypes
and drug resistance among newly diagnosed cases of HIV infection will
inform treatment recommendations, HIV drug and biotechnology development,
diagnostic testing, and vaccine development.
Specimens are primarily sought from laboratories that conduct confirmatory HIV diagnostic testing. Clinical sites that diagnose and/or treat HIV patients, and other HIV testing sites will be responsible for ensuring that laboratories utilized for confirmatory HIV testing comply with Minnesota disease reporting rules.
Specimen eligibility for HIV subtype and drug resistance testing will be assessed upon receipt at the MDH Public Health Laboratory. Eligible specimens include those from persons who:
- are diagnosed with HIV infection;
- have not been previously diagnosed with HIV more than 12 months prior;
- have not been exposed to antiretroviral drugs;
- have not already received HIV drug resistance and subtype testing through this surveillance program; and
- reside in Minnesota.
Results of subtype and genotypic drug resistance testing will be returned to HIV surveillance staff and included in the MDH surveillance case record. Patients may indicate a physician or other health care provider to receive a copy of the subtype and drug resistance test results at the time of diagnosis or any time thereafter. Physicians may request a copy of a patient’s subtype and drug resistance test results for purposes of medical treatment.
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