Select A Disease That Affects Humans Or Animals And Its Caus

Select A Disease That Affects Humans Or Animals Whose Causative Agent

Select a disease that affects humans or animals whose causative agent is a bacterium, virus, fungus, protozoa, or other microorganism. (I chose hepatitis B) Create and deliver a presentation on your chosen disease in which you report on each of the following in detail: Causative Agent: Describe and classify the microbe involved. If known, explain how the microbe causes/transmits the disease or interferes with normal body function. Also, describe the vector and/or life cycle for the microbe (if applicable). Population(s) affected: What population(s) is/are at highest risk of contracting the disease? Are there any groups of people who should be tested? Please include statistical/geographical data and trends (from the Centers for Disease Control and Prevention, World Health Organization, or other source [to an external site], to an external site. , etc.). Course of Disease: What are the usual signs/symptoms of someone with the disease? How is the disease diagnosed? What is the usual time course for recovery? Are there complications and/or long-term effects? Interventions: Describe possible treatments and/or medical interventions. Is there a vaccine available? How can the disease be best prevented or kept under control?

Paper For Above instruction

Hepatitis B: Causes, Transmission, Population Risks, and Prevention

Hepatitis B is a viral infection that primarily affects the liver and is caused by the hepatitis B virus (HBV). It is a significant global health concern, classified within the Hepadnaviridae family and genus Orthohepadnavirus. HBV is a DNA virus characterized by its ability to integrate into the host genome and establish chronic infections. The virus primarily infects human hepatocytes, leading to inflammation, liver damage, and, in some cases, liver cirrhosis or hepatocellular carcinoma.

Causative Agent

The causative agent of hepatitis B is the hepatitis B virus (HBV), a small, enveloped DNA virus measuring approximately 42 nanometers in diameter. HBV belongs to the family Hepadnaviridae and the genus Orthohepadnavirus. It has a partially double-stranded DNA genome and replicates via reverse transcription within the infected cells. The virus infects the liver by attaching to hepatocyte surface receptors, mainly the sodium taurocholate cotransporting polypeptide (NTCP). The infection interferes with normal liver function by inducing inflammatory responses, hepatocyte injury, and, in chronic cases, liver fibrosis and carcinogenesis.

Transmission and Life Cycle

HBV is primarily transmitted through exposure to infectious blood and body fluids. Common routes include sexual contact, sharing of needles, transfusions of contaminated blood products, and vertical transmission from mother to child during childbirth. The hepatitis B virus has a complex life cycle involving entry into the hepatocyte, uncoating, replication of its DNA, and assembly of new virions that are released to infect additional cells. The virus can persist in the blood for at least six months and even longer in some cases, leading to a high rate of transmission in endemic areas.

Population Affected

Globally, over 250 million people are chronically infected with HBV, with the highest prevalence in sub-Saharan Africa, East Asia, and parts of Southeast Asia. High-risk groups include healthcare workers, intravenous drug users, individuals with multiple sexual partners, and newborns from hepatitis B-positive mothers. Infants and young children are at a higher risk of developing chronic hepatitis B infections due to their immature immune responses. Certain groups, such as pregnant women, should be routinely tested for hepatitis B surface antigen (HBsAg) to prevent vertical transmission.

According to the World Health Organization (WHO), the incidence of new HBV infections has decreased significantly in countries with widespread vaccination programs, but endemic regions still face high burdens of disease and associated complications, such as liver cirrhosis and hepatocellular carcinoma.

Course of Disease

The clinical presentation of hepatitis B varies depending on age, immune status, and whether the infection is acute or chronic. Acute hepatitis B usually manifests with nonspecific symptoms such as fatigue, jaundice, anorexia, abdominal pain, and dark urine. Some individuals may remain asymptomatic. Diagnosis is confirmed through detection of specific serological markers, including hepatitis B surface antigen (HBsAg), hepatitis B e antigen (HBeAg), and hepatitis B core antibody (anti-HBc). Liver function tests often show elevated transaminases.

The typical course involves immune-mediated clearance in adults, leading to recovery within six months. However, infants and immunocompromised individuals are at risk of developing chronic hepatitis B, which may progress to cirrhosis or liver cancer over decades. Long-term complications include chronic hepatitis, liver failure, and hepatocellular carcinoma. The window period for recovery varies, but in instances of chronic infection, lifelong management may be necessary.

Interventions and Prevention

Treatment options for hepatitis B include antiviral medications such as tenofovir and entecavir, which suppress viral replication and reduce liver inflammation. Though these medications do not cure the infection, they significantly decrease the risk of progression to severe liver disease. Interferon-alpha therapy can also be used, especially in younger patients or those with specific genotypes.

There is a highly effective vaccine for hepatitis B that provides long-term immunity. The hepatitis B vaccine is typically administered in a three-dose series, beginning at birth, with booster doses sometimes recommended for high-risk groups. Prevention strategies also include screening blood products, practicing safe sex, avoiding sharing needles, and vaccinating infants and high-risk populations.

Public health interventions, including education campaigns and routine screening, particularly among pregnant women, have substantially reduced transmission rates in many countries. Continued efforts are essential to achieve global hepatitis B control and eventual eradication.

References

• World Health Organization. (2022). Hepatitis B. WHO. https://www.who.int/news-room/fact-sheets/detail/hepatitis-b
• Centers for Disease Control and Prevention. (2022). Hepatitis B Surveil­lance. CDC. https://www.cdc.gov/hepatitis/statistics/index.htm
• Ganem, D., & Prince, M. (2004). Hepatitis B Virus Infection—Natural History and Clinical Management. New England Journal of Medicine, 350(11), 1118–1129.
• Lok, A. S., & McMahon, B. J. (2009). Chronic Hepatitis B: Update 2009. Hepatology, 50(3), 661–662.
• WHO. (2017). Global hepatitis report 2017. World Health Organization.
• Lee, W. M. (2019). Hepatitis B virus infection. New England Journal of Medicine, 381(3), 223–232.
• Rehermann, B. (2013). Pathogenesis of chronic viral hepatitis: differential roles of immune responses. Trends in Immunology, 34(4), 179–187.
• Stevens, C. E., & Lee, W. M. (2004). Viral hepatitis and liver cancer. Hepatology, 39(4), 1023–1029.
• Chen, J., & Zhuang, H. (2018). Advances in hepatitis B virus immunoprophylaxis. World Journal of Clinical Cases, 6(14), 911–921.
• Ott, J. J., et al. (2012). Global prevalence of hepatitis B antibodies. Annals of Epidemiology, 22(6), 434–445.