A Guide to HIV/AIDS Epidemiological and Surveillance Terms

[Previous] [Table of Contents] [Next]

Frequently Used Terms in HIV/AIDS Monitoring and Epidemiological Research in Canada

AIDS CASE
(See also AIDS CASE REPORT, CASE)

An AIDS case is a person who has received an AIDS diagnosis. Once the health care provider reports the AIDS case to the local public health authority, this person is described as a reported AIDS case in surveillance databases and reports.

AIDS CASE REPORT
(See also AIDS CASE, REPORTED AIDS CASES and FAQs 6, 8, 9)

An AIDS case report is documentation of a person's confirmed and reported AIDS diagnosis.

These reports include patient information, laboratory data and the activities that put the person at risk for transmission of HIV. The information recorded forms the basis of the surveillance data reported at the provincial and territorial level, as well as to the Centre for Infectious Disease Prevention and Control (CIDPC) at the federal level. Information reported to CIDPC does not include names nor does it identify anyone.

AIDS DIAGNOSIS
(See also FAQs 8, 16, 17)

In Canada, AIDS is diagnosed if a person has

1. undergone testing for HIV and received a positive result and
2. has one or more of the clinical illnesses, or indicator diseases, that characterize AIDS.

This is the current definition of AIDS (2002) and is uniform across all Canadian provinces and territories. This definition also applies to 48 countries of the World Health Organization European Region, Australia and New Zealand. It is important to note that in the United States, a person must also have a CD4 T-lymphocyte count less than 200 cells per cubic millimetre of blood (< 200/µL) in order to meet the definition of an AIDS case.

The Canadian definition of an AIDS diagnosis has changed over time as more information was gathered on the disease. For example, the list of indicator diseases from 1987 expanded in 1993 to include the following:

• Pulmonary tuberculosis: tuberculosis (TB) in the lungs;
• Recurrent pneumonia: a pneumonia that keeps coming back or does not go away, often due to bacterial or fungal infections that do not usually cause pneumonia in people with intact immune systems; and
• invasive cervical cancer.

This was done to help solve the concerns of under-diagnosis of AIDS in women, injecting drug users and others.

ANONYMOUS HIV TESTING (Refer to HIV TESTING OPTIONS)

ANONYMOUS UNLINKED HIV TESTING

Anonymous unlinked HIV testing is the testing of a sample of either blood or saliva for the presence of HIV antibodies. No personal information is retained about the person to whom the sample belongs. As a result, there is no way to link the HIV test results back to the person who provided the sample. No one, including the person being tested, can ever know whose test results are positive or whose are negative.

Anonymous unlinked HIV testing is often carried out on blood left over after collection and testing for a different purpose, such as tests for rubella in pregnancy. All personal identifying information is stripped from the leftover blood sample before it is used for anonymous unlinked testing.

This kind of testing has been used in many countries for surveillance purposes, but in Canada, at present, it is most often carried out in research. It is used when the presence of existing HIV infection in a specific group, rather than in an individual, is to be determined.

The results of anonymous unlinked HIV testing have no direct individual use, but can provide important information about the level of HIV infection among a specific population.

[Previous] [Table of Contents] [Next]