Pathogens of the Digestive, Circulatory, Lymphatic, and Nervous Systems: Transmission, Virulence, and Disease

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Sep 10, 2025

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The discussion is based on the textbook readings from Microbiology (2016). Once you have completed your assigned readings (see Unit Overview page) and your assigned activities for this unit, please answer the prompt below:

Pick one bacterial, one viral, and one eukaryotic pathogen (for a total of three organisms) of the digestive, circulatory, lymphatic, and/or nervous systems. Discuss the following for your three chosen organisms:
- Modes of transmission
- Virulence factors
- Associated diseases

Struggling with where to start this assignment? Follow this guide to tackle your assignment easily!

Step 1: Introduction (1 short paragraph)

Start by introducing pathogens as disease-causing organisms.
Mention that you’ll focus on one bacterial, one viral, and one eukaryotic pathogen that affect different human body systems.
Example opening line:
Pathogens of the digestive, circulatory, and nervous systems contribute to a wide range of diseases, each with unique modes of transmission and virulence strategies. This discussion will examine one bacterial, one viral, and one eukaryotic pathogen, focusing on how they spread, the factors that make them harmful, and the diseases they cause.

Step 2: Choose Your Pathogens (1 paragraph each)

**Bacterial Pathogen: Helicobacter pylori (Digestive system)**

Transmission: Oral-oral or fecal-oral route, often through contaminated food or water.
Virulence factors: Urease enzyme (neutralizes stomach acid), flagella (motility), toxins that damage gastric mucosa.
Disease: Chronic gastritis, peptic ulcers, and associated with gastric cancer.

Viral Pathogen: Human Immunodeficiency Virus (HIV) (Circulatory/Lymphatic system)

Transmission: Bloodborne (sexual contact, sharing needles, mother-to-child).
Virulence factors: Reverse transcriptase (rapid mutation), gp120 protein (binds to CD4 receptors), integration into host genome.
Disease: Acquired Immunodeficiency Syndrome (AIDS).

**Eukaryotic Pathogen: Trypanosoma brucei (Nervous system)**

Transmission: Bite of the tsetse fly (vector-borne).
Virulence factors: Antigenic variation of surface glycoproteins (helps evade immune system).
Disease: African sleeping sickness (trypanosomiasis), which can progress to neurological symptoms and coma.

Step 3: Conclusion (1 short paragraph)

Summarize how different pathogens use distinct strategies to infect and survive.
Emphasize the importance of understanding transmission and virulence factors for prevention and treatment.

Step 4: APA Tips for References

Since your professor requires sources from Microbiology (2016), you’ll definitely cite the textbook. If you add outside sources (optional), cite them too.

Example:
OpenStax. (2016). Microbiology. OpenStax, Rice University. https://openstax.org/details/books/microbiology

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