HIV contact tracing, also sometimes called HIV partner notification, is the practice of identifying, locating and informing someone that a partner they have had sex or used drugs with has been diagnosed with HIV. Contact tracing is meant to encourage the partners to test for HIV to identify new HIV infections as early as possible.
This article will review what is known about the acceptability and effectiveness of contact tracing strategies and provide a snapshot of new technologies and promising approaches used for contact tracing in Canada.
Research tells us that the risk of passing HIV on to others is substantially higher during the first few months of HIV infection. Some research suggests it can increase the risk by as much as 2500%.1-3 This means that early identification of HIV infection, combined with effective prevention counselling, should help to reduce the transmission of HIV. We know that when someone learns of their HIV status, they typically take measures to prevent transmitting HIV to others.4 Contact tracing is an important tool to identify people in the acute stages of HIV infection. Finally, we also know that effective linkage to care, and the initiation of treatment when the client is ready, has the potential to greatly reduce HIV transmission.
Early identification of HIV infection also benefits the individual. People who know they live with HIV can seek care and treatment, and early treatment can improve their health and well-being. People living with HIV who begin treatment shortly after diagnosis and take the required medicines every day are expected to live a near-normal lifespan.5 Benefits of care can also include receiving an array of medical and social services such as preventative treatment (prophylaxis) for opportunistic infections, treatment for sexually transmitted infections (STIs), treatment for substance use and mental health conditions, as well as access to income supports and housing.
The Canadian Guidelines on Sexually Transmitted Infections provide recommendations for contact tracing. According to these guidelines, partner notification may be done by the patient, healthcare provider or public health authority, or a combination of more than one may be used to notify different partners of the same person.
Of the 13 other jurisdictions in Canada, 11 have public health laws that cover contact tracing. These can be divided into two groups: British Columbia, Saskatchewan, Manitoba, Prince Edward Island, Nunavut and Northwest Territories require contact tracing to be performed when someone is diagnosed with HIV. In comparison, Alberta, Ontario, New Brunswick, Nova Scotia and Yukon allow contact tracing to occur.6 The remaining two jurisdictions (Quebec, Newfoundland and Labrador) have no specific laws mandating contact tracing, but health officials conduct contact tracing based on available guidelines.6
Whether healthcare providers and public health staff follow contact tracing guidelines with every client may be impossible to know. British Columbia has begun tracking whether public health has followed up with newly diagnosed patients. About 70% of these patients in 2013 had a record of public health follow-up.7 In the United States, there is some evidence that follow-up rates are much lower.8
There are three main contact tracing methods used in Canada:
Patient-referral contact tracing is when a person newly diagnosed with HIV tells (notifies) their sexual and drug-using partners that they may have been exposed to HIV. Typically, the person, sometimes called the index patient, is helped by their healthcare provider or public health staff to figure out who should be told and how to tell them.
Provider-referral contact tracing is when a healthcare provider or someone from public health notifies the index patient's sexual or drug-using partners that they may have been exposed to HIV.
Contact tracing is also sometimes done through contract referral programs. This is a hybrid method where the individual tells some of their contacts and their healthcare provider or public health staff tells others. In some instances, if a patient has not told their partners within an agreed-upon timeframe, their healthcare providers or public health staff will complete notification for them.
Depending on which method of contact tracing is used, there are typically ways for the index patient's anonymity to be preserved when disclosure is made to potential contacts.
One of the obstacles to effective contract tracing is the willingness of providers to do contact tracing or to refer clients to public health for contact tracing. Although most providers are in favour of contact tracing,9 studies have shown that providers are inconsistent in offering it. In one American city, as many as 48% of index patients were not referred for contact tracing.8 Even when a person newly diagnosed with HIV shares their contacts with a healthcare provider or public health nurse, there is no guarantee that their contacts will be notified. One study from the United States estimated that only 32% of notifiable partners were reached when contacts were shared.10
The second obstacle to effective contact tracing is the ability to locate and inform contacts. Increasingly this is becoming a problem with the introduction of new technologies, which connect people to new sexual partners, often anonymously. In a study out of the United States, 12% of gay and other men who have sex with men (MSM) and heterosexuals could not share their contacts' information because they did not know their sexual partners' names.11
Patient-referral contact tracing is acceptable to clients.12-14 The acceptability of patient-referral contact tracing ranges from 55% to 97% when clients are asked if they would, hypothetically, be willing to personally disclose to partners if they were diagnosed with HIV.9
However, when people recently diagnosed with HIV are asked whether they prefer to notify their partners personally or to have a healthcare provider or public health professional do it for them, more people choose to have their providers notify their contacts than choose to tell their partners themselves.9
Overall, patient-referral contact tracing tends to work better than provider-referral contact tracing when index patients have had unprotected sex, when individuals know how to find their sexual partners, and when they do not have any casual sex partners.15
Provider-referral contact tracing is also acceptable to clients. Acceptability varies depending on sexual orientation,9 gender,9 drug-using behaviours,9 and what type of healthcare provider (public health professional or physician) would be notifying partners of their potential exposure.16 Acceptability ranges from 80% among MSM to 92% among heterosexual men.9
Contact tracing seems to be effective at getting people to test for HIV and finding new HIV cases. A systematic review found that 63% of notified partners were tested for HIV.17 The same systematic review also showed that the average percentage of people of those contacted who tested positive was 20%, with a range of 14% to 26%.17
Contact tracing is also effective at getting untested people into testing. In one study, 22% of people who tested as a result of contract tracing had never had a test before and 41% had no plans to be tested within the next 6 months.11
Contact tracing is effective at reducing risky behaviours. An American study found a reduction in the usual needle-sharing behaviour and number of sex partners in people who were notified and tested for HIV. When a notified person was diagnosed with HIV, an 80% reduction in risk behaviours at 6 months was shown.18 When the notified person tested negative for HIV, there was a 50% reduction in risk behaviours.18
Finally, contact tracing appears to be cost-effective. Cost-effectiveness of contact tracing can be measured in two ways: how much does it cost to prevent a new infection or how much does it cost to find a new infection?
In the United States in 2004, it was estimated that the lifetime direct cost of medical care for someone living with HIV was about US$385,000.19 It has also been estimated that HIV contact tracing costs US$6,100 to prevent a new infection, which is significantly less than the cost of providing medical care to someone living with HIV.19
It has been estimated that if the cost of finding a new HIV infection is below US$30,000, then it would be cost-effective.20 A study in San Francisco found that it cost about US$7,081 to find a new infection,21 well below this estimated cost, making it a cost-effective intervention. However, it should be noted that these studies are almost 10 years old and new studies are needed to update these numbers.
There are new approaches to contact tracing to reach people who may not be reached by more traditional approaches (in-person and telephone). Email, email postcards (e-cards) and text messaging can be used by both patients and providers to notify someone of a potential exposure to an STI, including HIV.
One program in North Carolina used email and text messaging for contact tracing for syphilis and HIV and increased notifications by 600%22 when compared to data collected on traditional contact tracing approaches. Out of 362 people notified using email, seven new cases of HIV and 11 new cases of syphilis were diagnosed.22
One such technology, inSPOT, has been introduced in British Columbia, Toronto and Ottawa. inSPOT is a website that allows people recently diagnosed with an STI to send e-cards (without using their personal email address) to their sexual partners to let them know they may have been exposed. The service also lets them maintain their anonymity if they wish. Although the approach is acceptable to both heterosexual people (65%) and gay men (73%),23 the evidence for its effectiveness in the long term is weak.24
Although email remains one of the most widely used new technologies in contact tracing, there is some evidence to suggest that using text messaging for contact tracing could improve notification outcomes. A study in North Carolina concluded that text messaging was effective with contacts who did not respond to traditional forms of follow-up and/or email notification.22 Before using this approach, however, service providers should be mindful that text messaging is not considered a secure form of communication.
Overall, the use of new technologies, although acceptable for contact tracing, are not always preferred where multiple options are available.25 According to one study among men and women diagnosed with chlamydia, the most appropriate option reported by participants was in-person disclosure.25 This same study found, however, that participants considered email or text was appropriate when the person being notified was a casual partner or if the relationship had ended badly.
In 2012, Saskatchewan had the highest rate of new HIV diagnoses in Canada at 17 diagnoses for every 100,000 people.26 This is almost triple the national rate of six diagnoses for every 100,000 people.26 Sixty-seven percent of new HIV diagnoses in Saskatchewan in 2012 were attributed to injection drug use,27 and 74% were among Aboriginal peoples.27
Since 2005, Saskatoon Health Region has enhanced a traditional approach to contact tracing using a social network strategy. In addition to index cases being asked for their immediate drug use and sexual contacts, they are also asked who among their social networks would benefit from the offer of testing and counselling but who did not come into immediate contact with them. This approach focuses on the social context in which risky behaviours occur and engages peers to identify those people in their networks who may be at higher risk for HIV.
In 2004, before the enhanced approach was implemented, the rate of new HIV diagnoses in the Saskatoon Health Region was 5.57 per 100,000 people. In 2005, after the implementation of the social networking strategy, the number of new HIV diagnoses in the Saskatoon Health Region increased dramatically to 20 per 100,000 people. These numbers were compared to another health region in Saskatchewan, which did not implement the social network strategy. The rate of new diagnoses did not change in the region that was not using the enhanced approach.28
Since 2011, Vancouver Coastal Health has taken a more robust approach to traditional HIV contact tracing services. The program engages public health nurses in HIV contact tracing as soon as someone is diagnosed with HIV. Since every new HIV infection in Vancouver is reported to the Vancouver Coastal Health Communicable Diseases Control, nurses follow up with healthcare providers and clients to determine how best to perform contact tracing. Clients are encouraged to allow public health staff to notify their contacts or to assist them in notifying them.
In addition, Vancouver Coastal Health has implemented a social networking approach. Clients who may not know the names and contact information of their sexual partners, can instead disclose where contacts were met. If, for example, a contact was met at a bathhouse, public health nurses would set up additional or extended HIV testing clinics at that venue.
Vancouver's enhanced contact tracing service has been critical to the increase in the percentage of people aware of their status. The HIV positivity rate for contacts tested through this program was 12%, significantly higher than the positivity rates for other testing strategies being used in Vancouver at the same time. Key to the success of increasing the number of people living with HIV who are aware of their status has been the measurement of outcomes, such as proportion of partners identified, reached, tested and diagnosed.
Contact tracing in some areas of Canada may not currently be occurring as outlined in the Canadian, provincial or territorial guidelines. Learning about how contact tracing is conducted in your area may be key to improving the experience of people newly diagnosed with HIV and reducing the number of people living with HIV who are unaware of their status.
The criminalization of HIV and the fear some clients may have of disclosing their status are real. Service providers may need to work with clients to help them make informed choices about how to tell their contacts in a way that feels safe for them. It may be important in your work to discuss with people recently diagnosed with HIV the value of telling their partners that they may have been exposed to HIV. Service providers can encourage newly diagnosed clients to inform their contacts personally, through public health staff, or through inSPOT, where it is available.
In some instances, service providers may be able to work with public health staff and healthcare providers to improve contact tracing so that clients concerned about disclosure feel safe sharing their contacts' information. Certain populations may also need a more appropriate approach to contact tracing. Positive Living B.C., for example, has worked with Vancouver Coastal Health Communicable Diseases Control to strengthen contact tracing for MSM.
There is a significant lack of research in the Canadian context on HIV contact tracing, particularly regarding current trends. Contact tracing has the potential to significantly reduce the number of people living with HIV who don't know their status. More needs to be done to understand the acceptability and effectiveness of all types of contact tracing services in Canada.
This article drew heavily upon the work of the National Collaborating Centres for Infectious Diseases and their evidence reviews: HIV Partner Notification: A review of the evidence with recommendations to move the field forward (Nicole Findlay) and New Technologies for Partner Notifications for Sexually Transmitted Infections (Colin Lee and Mayank Singal).
HIV disclosure: a legal guide for gay men in Canada -- HIV & AIDS Legal Clinic Ontario (HALCO), Ontario's Gay Men's Sexual Health Alliance GMSH), CATIE
Logan Broeckaert holds a master's degree in history and is currently a researcher/writer at CATIE. Before joining CATIE, Logan worked on provincial and national research and knowledge exchange projects for the Canadian AIDS Society and the Ontario Public Health Association. Margaret Haworth-Brockman is the program manager at the National Collaborating Centre for Infectious Diseases (NCCID), which provides evidence for action in public health. NCCID has numerous resources available (www.nccid.ca) on HIV, and also works to foster working partnerships and networks to improve information exchange. Margaret's past work includes developing new resources on gender and HIV and AIDS for communities in Canada, Belize, and southern African countries.