Introduction to Communicable Diseases
Communicable diseases spread from one person to another, from an animal, or even the environment, to a person. Typically this occurs through airborne droplets or bodily fluids containing a virus, bacterium, or parasite. Nutritional, maternal, and neonatal conditions are often grouped with communicable diseases in the study of G B D. This group is often referred to as “Group 1”
Burden of Communicable Diseases
Communicable diseases such as H I V, tuberculosis, and malaria, present a significant burden for low-income countries (over 50% of total DALYs in some Low S D I countries) but less than 10% for high-income countries. You will often see these three diseases called “the big three”.
HIV
Globally, 38 million people are living with H I V as of 2019, 19% of which are unaware of their status. Over 68,000 individuals are currently living with H I V in Canada, 14% of whom are unaware of their HIV status
Tuberculosis
In 2019, 10 million people contracted T B worldwide. In Canada there were 1,796 cases of active tuberculosis reported. Two populations - foreign-born individuals and Indigenous Peoples - accounted for the majority of cases.
Malaria
In 2019, there were an estimated number of 229 million cases of malaria worldwide. The Canadian infectious disease surveillance system has reported an average of 538 malaria cases per year since 1990, and Statistics Canada reported an average of one death per year
Communicable Diseases: Human Immunodeficiency Virus (HIV)
HIV is a disease that attacks the body’s white blood cells and weakens the body’s immune system. By the end of 2019, there were 38 million people in the world living with H I V with only 67% of them having access to antiretroviral therapy. In 2019, 690,000 people lost their lives to HIV, while 1.7 million new infections were diagnosed. To date, HIV has taken 33 million lives, making it one of the major global public health issues
Mechanisms of Action
HIV infects white blood cells called helper T cells, destroying them over time and eventually causing Acquired Immunodeficiency Syndrome (AIDS)
Transmission
HIV is spread from person to person via bodily fluids (i.e. semen, vaginal fluids, blood, and, to a lesser degree, breast milk).
Treatment and Prevention
HIV is typically treated using antiretroviral therapy (A R T), which can greatly prolong life and suppress symptoms, but does not cure the disease
Prevention Strategies for HIV Include
Single condom use
Elimination of mother-to-child spread with ART during pregnancy and breastfeeding
Testing and counselling services
Harm reduction for people who use drugs, including needle and syringe programs
Antiretroviral Therapy (A R T)
A treatment that consists of taking multiple antiretroviral drugs simultaneously to inhibit the different stages of the virus’s life cycle
The HIV/AIDS Epidemic Among Indigenous Canadians
- Social and economic factors have placed the Indigenous peoples in Canada at a higher risk of H IV/AIDS compared to non-Indigenous Canadians. In 2017, Indigenous Peoples accounted for only 4.9% of Canada’s total population, yet made up 20.1% of total H I V cases
- Socioeconomic factors that may contribute to the increase the risk of H I V/AIDS in Indigenous Peoples include domestic violence, stigma, discrimination, and injection drug use. Additionally, the mistrust and lack of health services further perpetuates poor HIV and health outcomes within this population
HIV/AIDS Risk Factors Among Indigenous Canadians
- Among the total Indigenous population, Indigenous youth are at a greater risk of contracting H IV/AIDs. Unfortunately, a lack of health education services and denial of this crisis has resulted in a low-perceived risk of the virus in youth.
- Furthermore, substance use, particularly injection drug use, is strongly associated with H I V infection among Indigenous youth in Canada. Indigenous youth report a higher likelihood of sharing equipment and less access to risk reduction programs such as methadone clinics or needle-exchange programs, putting this population at 22 times more at risk of H I V than the general population
Barriers to Substance Use Harm Reduction Programs
- Barriers to receiving methadone treatments includes the lack of on-site methadone treatment and the need to travel to off-site methadone programs. This would mean long distance travelling and a lack of counselling and support for these Indigenous methadone patients.
- Not only do Indigenous Peoples have lower access to risk reduction programs, many Indigenous communities also have a stigma around treatment programs. In a 2016 study conducted with members of the First Nations communities in New Brunswick, Canada, it was found that abstinence-based therapy is the preferred treatment method. This is because many members of the communities view methadone treatments as “replacing one drug with another”. This stigma developed due to the lack of health education services and access to information regarding medication-assisted treatment in these communities. Those who have participated in the methadone treatment programs have reported experiencing discriminatory behaviours from others in the community
Canadian Aboriginal AIDS Network
- Fortunately, there are programs and services being created with a holistic approach to H I V and AIDS, other communicable diseases, and co-morbidity issues. One such service is the Canadian Aboriginal Aids Network (C A A N), which is a not-for-profit established in 1997 that represents over 340 member organizations and individuals to ensure access to H I V and AIDS related services.
- The C A A N promotes a Social Determinants of Health Framework through advocacy, and provides accurate and up to date resources on these issues in a culturally relevant manner for Aboriginal Peoples wherever they reside
Communicable Diseases: Turberculosis (TB)
Tuberculosis (T B) is caused by Mycobacterium tuberculosis; a bacterium that has infected one quarter of the world’s population. However, only 5-15% of those infected will develop an active T B infection. The risk is higher in people with a compromised immune system, such as those who are malnourished or co-infected with H I V. In 2019, T B infected 10 million people and was responsible for 1.4 million deaths.
Mechanisms of Action: Turberculosis (TB)
- T B usually attacks the lungs (pulmonary), but can also affect other parts of the body (extrapulmonary), including lymph nodes, kidneys, urinary tract, and bones
- When an individual has M. tuberculosis bacteria in their body but does not feel sick or show symptoms, they have latent T B (L T B). If L T B goes untreated, approximately 5-10% of infected individuals will develop active T B. Individuals with active T B show signs and symptoms, and are considered infectious.
Transmission: Turberculosis (TB)
T B is primarily an airborne disease that is spread through the air from person to person. When a person with infectious T B coughs or sneezes, droplet nuclei containing M. tuberculosis are released into the air and if another person inhales air containing these droplet nuclei, they may become infected.
Treatment and Prevention: Turberculosis (TB)
- L T B can be treated and cured with antibiotics as a means to prevent active T B from developing. When individuals have active T B, they have to take multiple antibiotics for 6-9 months to kill all the bacteria (compared to 3-4 months for latent infection).
- Like with any other antibiotic treatment, there is variable adherence, with many individuals stopping the antibiotics early. Such behaviour has caused drug resistance to become a major global health concern. If someone is exposed to or infected by an individual with multi-drug resistant T B (M D R T B), preventative treatment may not be an option
Impact of TB in Indigenous Communities in Canada
- Unlike the success of Indigenous communities in facing COVID-19, which you learned about in Module 02, Indigenous communities have struggled with high and persistent T B infections rates. In most of Canada, the risks of developing active T B are low, however, amongst Indigenous communities the risks are much higher. For instance, T B infection rates among First Nations individuals living on reserve is more than 40 times that of the non-Indigenous Canadian population
- Indigenous individuals are at greater risk of contracting and developing active T B often due to lack of health promoting conditions. These conditions include living in overcrowded and poorly ventilated homes, lack of food security, and comorbidities such as diabetes, H I V, etc.
- In response to the alarming T B rates among Indigenous Peoples in Canada, communities and governing bodies have taken action
Steps Aimed at Reducing TB Rates in Indigenous Communities
- For example, in 2016, the active T B rates among Inuit living in Inui Nunangat was more than 300 times the rates of the non-indigenous Canadian population. In 2017, Jane Philpott, then Minister of Indigenous Services, and the Inuit Tapiriit Kanatami announced the launch of an Inuit T B Task Force to study T B rates in Indigenous communities. In early 2018, an explicit commitment was made to eliminate T B among Inuit in Inuit Nunangat by 2030, with an interim reduction in the reported rate of active T B of at least 50% by 2025
- By the end of 2018, the Inuit Tapiriit Kanatami released an Inuit Tuberculosis Elimination Framework.
6 focus areas highlighted in the framework
- Enhance TB care and prevention programming
- Reduce poverty, improve social determinants of health and create social equity
- Empower and mobilize communities
- Strengthen TB care and prevention capacity
- Develop and implement inuit specific solutions
- Ensure accountability for TB elimination
Communicable Diseases: Malaria
Malaria is caused by the parasite Plasmodium, which can be transmitted between humans by mosquitoes. Malaria is more prevalent but less deadly than H I V, with 229 million cases and 409 000 deaths in 2019. The W H O Africa region carries the greatest burden from malaria having 94% of all global cases in 2019, with six countries accounting for almost half of all deaths worldwide. These countries are: Nigeria, the Democratic Republic of the Congo, United Republic of Tanzania, Burkina Faso, Mozambique, and Niger. In 2019, children under five accounted for 67% of all malaria deaths worldwide
Mechanisms of Action: Malaria
- After a dormant period in the liver, Plasmodium enters the bloodstream and infects the red blood cells, often causing them to burst. There is also evidence that Plasmodium impairs the ability of key cells of the immune system to trigger an efficient immune response, which might explain why patients with malaria are susceptible to a wide range of other infections and fail to respond to several vaccines
- Symptoms may include headache, abdominal pain, chills, shaking, fever, and sweats. Malaria can cause seizures, anemia, jaundice, heart failure, kidney failure, coma, and even death.
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