CATIE News - Understanding the needs of new Canadians can help reduce HIV transmission risks
2011 Feb 10 - In high-income countries such as Canada, great strides have been made in minimizing the risk of mother-to-child transmission with all of the following steps:
- use of anti-HIV therapy (commonly called ART or HAART) during the mother's pregnancy in order to reduce the amount of HIV in the mother's blood as much as possible
- intravenous AZT (Retrovir, zidovudine) during delivery
- delivery of the baby via Caesarean section
- oral AZT for the baby for the first six weeks of life
- use of baby formula instead of breastfeeding (breast milk can transmit HIV)
Ideally, these steps would be supplemented by counselling before the woman becomes pregnant, along with further counselling and care during pregnancy, the provision of free infant formula at birth and until the infant is old enough to eat solid food, and close medical monitoring of the baby and mother to ensure that both are healthy.
Researchers in Calgary, Alberta, recently published the results of an investigation into a case of mother-to-child transmission in that city. Their results suggest that a series of intersecting events likely played a role in the transmission of HIV, despite good medical care. As a result of the investigation, changes to the social and biomedical care, monitoring and support that HIV-positive women receive in that city have been made. Hopefully, such changes will be able to limit future potential cases of mother-to-child transmission in Calgary. The lessons learned by the Alberta physicians are also relevant to doctors, nurses, pharmacists, social workers and psychologists in other regions and countries where immigrants arrive from places where HIV is relatively common.
Standard operating procedures
Calgary doctors first interacted with the woman in her 26 th week of pregnancy. She had a university education, was fluent in English and had emigrated from sub-Saharan Africa. As part of regular screening done during pregnancy, she had tested HIV positive.
At the 28 th week of her pregnancy the woman began HAART, both for her own health and to reduce the risk of transmitting HIV to her fetus.
For the remainder of her pregnancy, the woman reported that she took HAART exactly as directed, a behaviour called adherence, and had no side effects. Her viral load in blood samples was below the level of quantification (BLQ); that is, below the level where it can accurately be counted by assays. Viral load test results that are BLQ are commonly referred to as "undetectable." In this case, the lower limit of quantification was 40 copies/ml. The assay used was the NucliSens HIV-1 QT assay made by bioMérieux in the United States. The woman's CD4+ count was about 200 cells.
According to clinic records, during pregnancy the woman had seven visits with her HIV specialists as well as "numerous pharmacy, dietary and nursing consultations," the investigators reported. Furthermore, they noted that she also regularly attended a clinic that specialized in counselling women who are considered to have "high-risk" pregnancies.
During labour the woman declined to have a Caesarean section, which would have also reduced the chances of the baby being infected. The woman was given intravenous AZT every hour until she gave birth. After birth, the baby was given oral AZT for six consecutive weeks.
As is the practice in high-income countries, nurses and doctors strongly discouraged the new mother from breastfeeding her infant, as this could pose another risk of HIV transmission. She was offered free baby formula.
After birth, nurses visited the woman once weekly to provide continued counselling and medication for the baby. The woman reported that she was experiencing mild depression but declined any treatment for this condition. She told medical staff that she continued to be adherent to HAART and was using formula to feed the baby. A review of HIV clinic attendance records found that she had missed a few appointments after the birth of the baby but clinic staff had thought that this was due to family-related issues.
At birth, three months and eight months of age, technicians used PCR (polymerase chain reaction) tests to assess the infant's blood samples for HIV's genetic material. The results suggested that the infant was not infected.
However, when the child was 12 months old, testing was done again and the results were not conclusive. So the test was repeated the 13 th month after birth. This time it was positive. Further analysis revealed that the child had the same strain of HIV-1 as the mother.
How did this happen?
Stunned by this result, a medical team launched an investigation to find out how the infant may have become infected. They found three intersecting circumstances that may have played a role, as follows:
- HAART may not have been fully effective because the woman may have been non-adherent from time to time when she was pregnant. This non-adherence, the investigators surmised, may have been due to a lack of family support, the burden of carrying the disapproving attitudes (stigma) that some people have toward HIV-positive people and fear of inadvertently disclosing her status.
- The assay used to assess HIV in her blood did not detect active HIV replication. Had it done so, her physicians and nurses would have been alerted to the possibility of a problem.
- Despite extensive pre- and post-pregnancy counselling about the danger of breastfeeding and the provision of free baby formula, the mother may have breastfed her child because of pressure from her family and cultural expectations in her community.
Pharmacy and pharmacology
The woman had "always claimed good adherence to HAART," noted the investigators. Yet sophisticated analysis of her stored blood samples collected during earlier clinic visits revealed the absence of HAART.
Next the investigators compared the woman's pharmacy records and found a difference in the amount of drugs prescribed and what the woman collected. Specifically, the team found that, at most, when obtaining prescription refills, the woman requested 63% of the medications prescribed by her physician. When questioned about this by investigators, she responded that her husband's lack of support for her adherence and her concern about inadvertent disclosure of her HIV status and possible stigma in the community all contributed to her poor adherence.
Viral load testing
In Canada, Australia, Japan, Western Europe and the United States, the most common subtype, or clade, of HIV is called subtype B. Most tests and diagnostic assays were originally developed for use in high-income countries and were optimized to detect subtype B virus. However, with travel and immigration of people from other countries and regions (particularly from Asia and sub-Saharan Africa) to high-income countries, other subtypes of HIV are appearing in Canada and other countries.
Occasionally, some HIV viral load assays routinely used in high-income countries may not be able to accurately assess viral loads from blood samples taken from people infected with a non-subtype-B strain of HIV. In such cases, viral load assays may falsely suggest that very little or no production of HIV is taking place in the blood.
The viral load assay used throughout the woman's pregnancy to assess her blood was made by bioMérieux. The Calgary investigators retested her blood with a different assay called Versant HIV-1 RNA 3.0 made by Siemens Healthcare Diagnostics. With this second assay, the woman's viral load was detectable three months before and up to 18 months after the birth of the baby. During this period, the Versant assay revealed that her viral load ranged between 2,300 and 5,500 copies/ml.
Unfortunately, breastfeeding is a well-documented method of transmitting HIV. The investigators noted that in some cultures mothers are "under substantial pressure to breastfeed as a demonstration of good motherhood." In their report, the investigators mentioned findings from a study in sub-Saharan Africa where women, despite being educated about the risks of HIV transmission associated with breastfeeding, "continued to breastfeed even when formula was safe and available."
When investigators questioned the woman about the possibility of breastfeeding, she initially denied this behaviour. However, she later confirmed that because of pressure from family members who did not know about her HIV status and with her husband's encouragement, she had been breastfeeding the baby. Examination of the clinic's records revealed that the woman had told nurses, "my family have been giving me lots of formula."
Changes to practice
As a result of the investigators' findings, the Calgary clinic has made several important changes to their practices, including the following:
Records about pharmacy refills and pickups are now entered into the clinic's charts so that poor adherence is more likely to be detected.
- Viral load testing
The clinic has facilitated testing of four different viral load assays most likely to detect HIV subtypes other than B. Sub-typing analysis is now routinely done in blood samples from new HIV-positive patients. This helps doctors identify people who need additional laboratory testing.
- Cultural issues
Clinic staff now monitors more closely patients whose cultural background may strongly encourage breastfeeding. A priority for the clinic's nurses and social workers is to recognize and find ways to help HIV-positive men and women whose family, culture and community may negatively affect the care that such people need.
Culture, family and biology
The study investigators made this statement: "When caring for immigrant populations, physicians and other healthcare providers should consider the effects of biological differences in HIV subtypes on testing. In addition, sigma, denial, lack of family support and cultural expectations may lead to patient decisions with poor medical outcomes. Understanding and working with such issues will be of increasing importance in all developed countries with a growing population of immigrants with HIV infection."
The harmful effects of stigma on the health and psychological well-being of HIV-positive people in ethno-cultural communities in high-income countries is now well documented. Researchers who have interviewed members of ethno-cultural communities (from Africa, the Caribbean, and South and Southeast Asia) who are living in Canada, the Netherlands, Spain and Sweden have found that concerns about inadvertent disclosure of HIV status to their community can limit access to counselling, HIV prevention, care and treatment services. The fears and concerns of these HIV-positive people are grounded in their everyday reality, where disclosure has, in some cases, led to people being rejected by their families and shunned by friends and community members. This can lead to social isolation and psychological trauma and likely worsening health.
In the future, CATIE News bulletins will explore some of the findings from research on HIV stigma.
-Sean R. Hosein
O'Bryan T, Jadavji T, Kim J, Gill MJ. An avoidable transmission of HIV from mother to child. Canadian Medical Association Journal . 2010 Nov 22. [Epub ahead of print]
From Canadian AIDS Treatment Information Exchange (CATIE). For more information visit CATIE's Information Network at http://www.catie.ca
Source: CATIE: CANADIAN AIDS TREATMENT INFORMATION EXCHANGE