Epidemiology of HIV Epidemiology & Communicable Disease

Description of HIV

HIV is short for human immunodeficiency virus, and it the viral infection that can lead to AIDS or acquired immunodeficiency syndrome. The HIV virus remains in the body for life as the human body cannot rid itself of the virus; this is true even if the overt symptoms of HIV are absent ("CDC," 2015). The HIV virus spreads through body fluids, affecting specific cells (CD4 or T cells) associated with the immune system ("CDC," 2015). HIV destroys many CD4 cells over time to a degree that compromises the body's overall immune system leaving it incapable of fighting off infections and disease: this end stage of HIV infection is referred to as AIDS ("CDC," 2015). The CD4 cell count is fundamental to monitoring people living with HIV ("CDC," 2015).

HIV progresses through several stages with the first stage often -- but not always -- characterized by the following symptoms: Severe flu-like symptom consisting of fever, sore throat, enlarged lymph nodes, and rash occurring at two to four weeks following exposure ("CDC," 2015). It is important to note that many people infected with HIV have no symptoms whatsoever for 10 or more years. Even during the symptomatic phase just following exposure to the virus, carriers are highly infectious, but the HIV infection may not appear on an HIV test during this time ("CDC," 2015).

HIV infection in the United States is predominantly a result of having sex or sharing injection drug equipment with HIV-infected people ("CDC," 2015). For women living with HIV, transmission of the disease most frequently occurred as a result of heterosexual sex with a man infected with HIV (80%), while for men living with HIV, transmission is predominantly a result of homosexual sex (85%) ("CDC," 2015). Intravenous drug users may contract HIV through sharing needles, syringes, other equipment, and even rinse water The bodily fluids that are known to transmit HIV include: blood, semen, pre-seminal fluid, rectal fluids, vaginal fluids, and breast milk ("CDC," 2015). In order to transmit the virus, the bodily fluids must come into contact with mucous membrane or damaged tissue, or be directly injected into the bloodstream ("CDC," 2015). Less common transmission of HIV includes passing the virus to an infant during pregnancy, birth, or breastfeeding; or receiving blood transfusion or tissue / organ transplants contaminated by HIV ("CDC," 2015).

Treatment of HIV has evolved over the years and currently includes pre-exposure prophylaxis (PrEP) or post-exposure prophylaxis (PEP) ("CDC," 2015). The use of PrEP is intended to be used by people who are at high risk of contracting HIV; the treatments are used consistently as part of a daily regimen, along with other preventative options, such as condoms ("CDC," 2015). PEP is designed to be used after a single high-risk event in order to prevent HIV from replicating and spreading throughout the body. PEP must be started within three days of possible exposure and should actually be started immediately ("CDC," 2015). It is important to recognize that viral load can linger at 40 to 75 copies per milliliter of blood, which are undetectable levels ("CDC," 2015). As viral load increases to millions of copies per milliliter of blood, the risk of contagion increases ("CDC," 2015). Stopping medication or catching additional sexually transmitted diseases (STD) or hepatitis can increase the risk of spreading the disease as much as three to five times than if HIV is the only resident infection ("CDC," 2015). Acquiring an STD means that viral load will increase and CD4 cell count will decrease ("CDC," 2015). People whose CD4 levels and viral load reach critical levels are susceptible to the development of AIDS, which leaves them vulnerable to all sorts of opportunistic illnesses, including pneumonia and cancer ("CDC," 2015).

Treatment of people living with HIV includes a regimen of anti-retroviral therapy medications, commonly referred to as ART, and highly active antiretroviral therapy (HAART), or cART, which stands for combination antiretroviral therapy, indicating that two or more drug types are used in the treatment ("CDC," 2015). This can mean that cART regimens include nucleotide reverse transcriptase inhibitors (NRTIs), non-nucleotide reverse transcriptase inhibitors (NNRTIs), protease inhibitors (PIs), or integrase inhibitors, all of which interfere with an HIV infection and replication process at different stages ("CDC," 2015).

With regard to the epidemiologic triangle in HIV infections, the agent factor is biological as the HIV virus is caught from infected individuals ("CDC," 2015). The host factors in HIV include lifestyle choices, such as drug...

Environmental factors include sanitation of living conditions and local geology, as HIV is more prevalent in some regions and countries than in others, and the availability of health services ("CDC," 2015).
The chain of infection for the communicable disease referred to as HIV includes the following elements: The infectious agent; the reservoir; the portal of exit; the mode of transmission, the portal of entry, and the susceptible host ("CDC," 2015). The infectious agent is viral and the reservoir is human beings. The portal of exit is an exchange of bodily fluids, the mode of transmission is sexual contact and blood exposure, and the portal of entry includes sexual contact and breaks in mucosal barriers ("CDC," 2015). Matters related to the susceptible host are discussed throughout this paper, and relate most significantly to individual lifestyle choices with regard to injectable drug use and sexual ("CDC," 2015) ("CDC," 2015). The social determinants of health have to do with where people are born, grow up, work, age, and live -- and with all the associated systems that are in place or added to those contexts in order to address illness and disease ("CDC," 2015). Naturally, these social determinants of health are aspects of larger categorical forces such as economics, politics, education, and social policies.

Demographics of HIV

Since the AIDS epidemic began, nearly 78 million people have been infected with HIV, and approximately 39 million people have died of HIV ("WHO," 2013). By the end of 2013, roughly 36.0 million people were living with HIV worldwide ("WHO," 2013). The disease burden of the AIDS epidemic varies widely from country to country, and region to region, but the global estimate is roughly 0.8% of people from age 15 to 49 years of age are living with HIV ("WHO," 2013). Globally, the sub-Saharan region of Africa is the most severely affected area -- a region in which nearly one out of every twenty adults lives with HIV ("WHO," 2013). This figure represents nearly 71% of the people who live with HIV around the world ("WHO," 2013).

Estimating the prevalence and incidence of HIV / AIDS infections is complicated by the fact that an average 10-year spread separates the initial infection with HIV from the development of AIDS (Osmond, 2003). This means that trend data for AIDS is observed through a reliance on infection pattern data that is from approximately a decade earlier (Osmond, 2003). In order to best understand how the AIDS epidemic is progressing and to gauge the effectiveness of measures to control the spread of HIV, stakeholders study the incidence rates of HIV (Osmond, 2003). Access to robust HIV incidence data is difficult to achieve since small local studies spread across the country are the primary sources of this data (Osmond, 2003).

Prevalence data is used to generate estimates of the current national HIV disease burden, and to forecast the demands placed on systems that provide medical care and social services associated with the treatment and management of HIV / AIDS infections (Osmond, 2003). Prevalence data is more readily available than incidence data, however, it is important to recognize that a national representative surveillance system does not exist for prevalent infections (Osmond, 2003). This is to say that estimated on HIV prevalence must be based on the following: 1) Mathematical models that utilize reported AIDS cases; 2) Serological surveys conducted by various sources; and, 3) HIV infection reports from the states that do have laws that require reporting of communicable diseases (Osmond, 2003). Naturally, prevalence data quality and accuracy is limited according to the proportion and characteristics of people seeking HIV testing prior to receiving a diagnosis of AIDS (Osmond, 2003). It is fair to say that the prevalence data provides a minimal estimate of the number of people living with HIV -- but who have not developed AIDS -- plus the number of people reportedly living with AIDS (Osmond, 2003).

The Role of the CDC in HIV Prevention

The CDC provides leadership in the efforts to control the HIV / AIDS epidemic through its work with community, regional, state, national, and international partners. The Division of HIV / AIDS Prevention (DHAP) engages in activities related to surveillance, research, evaluation, and prevention activities that have the potential to impact the 1.1 million Americans who are living with HIV, which include the 21% of that figure who do not know they have contracted HIV. As new drug therapies extend the lives of people living with HIV or AIDS, the number of people seeking services has increased. The CDC…