INFECTIOUS DISEASES

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Acquired Immunodeficiency Syndrome (AIDS/HIV)

Reporting Obligations

AIDS/HIV is designated as a disease of public health significance and is reportable under the Ontario Health Protection and Promotion Act. Report suspect and confirmed cases within one business day to the local Health Unit.

Epidemiology

Aetiologic Agent:

The human immunodeficiency virus (HIV) is a retrovirus of which two types have been identified: type 1 (HIV-1) and type 2 (HIV-2). They are serologically and geographically distinct but have similar epidemiological characteristics. The pathogenicity of HIV-2 may be lower than that of HIV-1; they have genotypic and phenotypic differences. HIV-2 has lower disease progression and lower rates of mother-to-child transmission.

Clinical Presentation:

AIDS is a severe, life threatening clinical condition and is an advanced HIV related disease. This syndrome represents the late clinical stage of HIV infection resulting from progressive damage to the immune system, leading to one or more of many opportunistic infections and cancers of which bacterial pneumonia is one of the common presentations. Symptoms of acute HIV infection may include fever, arthralgia or myalgia, rash, lymphadenopathy, sore throat, fatigue, headache, oral ulcers and or genital ulcers, weight loss, nausea, vomiting or diarrhea. Acute symptoms, if present, occur two to four weeks after the initial infection and last from one to two weeks or as long as several months. In Canada, AIDS is diagnosed when a person with HIV develops one or more “AIDS- defining” symptoms.

Modes of transmission:

Person- to- person through unprotected sexual intercourse Contact with infected body fluids: sexual fluids, blood, and breast milk
The use of HIV infected-contaminated needles and syringes and some drug paraphernalia, including sharing by injection drug users
Transfusion of infected blood or its components, organ and tissue transplants
Contact of abraded skin or mucosa with body secretions such as blood, semen and CSF
The presence of another STI in either the source or the exposed person, particularly ulcerative lesions such as syphilis or genital herpes, increases the potential for sexual transmission of HIV.
Occupational exposure to HIV infection: percutaneous injury with a sharp object potentially contaminated with blood or other bodily fluid: mucous membrane exposure to blood or other bodily fluid
Vertical transmission from mother to infant during pregnancy, delivery or breast feeding
While virus has occasionally been found in saliva, tears, urine and bronchial secretions, transmission after contact with these secretions in the absence of blood has not been reported

Incubation Period:

Variable: time from initial infection to detectable antibodies (window period) is usually 1-3 months. The time from HIV infection to diagnosis of AIDS has an observed range of less than one year to 15 years or longer.

Period of Communicability:

Not known precisely; begins early after onset of HIV infection presumably extending throughout life. Infectivity during the first months is considered to be high; it increases with viral load, with worsening clinical status and with the presence of other STIs.

Risk Factors/Susceptibility

The Ontario Advisory Committee on HIV/AIDS has identified four populations at greatest risk of acquiring HIV/AIDS in Ontario, including gay and bisexual men, African and Caribbean Ontarians, Aboriginal Ontarians and people who use injection drugs. See Modes of Transmission for specific risk factors.

Diagnosis & Laboratory Testing

The diagnosis of HIV infection is based primarily on a positive serologic test. Persons with HIV infection may be totally asymptomatic. Therefore, serologic testing is recommended when there is a high index of suspicion (e.g., high-risk behaviour and/or suspicious clinical symptoms and signs). Persons may also present with specific opportunistic infections or other conditions indicative of underlying immunosuppression.

Treatment & Case Management

The “Canadian Guidelines on Sexually Transmitted Infections”, provides information related to: counseling, transmission, diagnosis, management, treatment and follow-up of patients.

Public Health staff will be involved in case and contact investigations.