Bio notes viral defences

Viruses and Transmission Methods

• Key Viruses Discussed:

  • Dengue

  • West Nile

  • Ebola

  • HIV

  • Herpes

  • Hepatitis A (Hep A)

  • Influenza

Classifying Transmission Methods

• Direct Transmission: Virus is directly transmitted from host to host.

• Indirect Transmission: Virus is transmitted through vectors, objects, or contaminated substances.

• Example Vectors: Mosquitoes are significant for diseases like Dengue and West Nile.

Symptoms Overview

• Ebola Symptoms:

  • Chills

  • Headaches

  • Rapid eye movement

  • Fever and potential bleeding (in severe cases)

• General Transmittable Symptoms: Many viruses like Ebola and West Nile share flu-like symptoms, which can cause confusion in self-diagnosis.

Case Study: West Nile Virus

• Transmission: Primarily through mosquitoes (vector).

• Symptoms: Flu-like symptoms; can lead to serious neurological issues.

Further Discussion: Rabies

• Symptoms: Often there are no immediate signs; generally flu-like symptoms may appear.

• Transmission: Direct through infected animals (e.g., bites).

HIV and Hepatitis A

• HIV Transmission:

  • Direct contact, primarily through sexual transmission, and indirect via contaminated needles.

  • Associated symptoms include sore lymph nodes and various rashes.

• Hepatitis A Symptoms:

  • Attacks liver; jaundice is a key indicator.

  • Spread mainly via contaminated food or water (indirect).

Disease Prevention and Health Practices

Hygiene Practices

• Importance of washing hands frequently to prevent viral infections.

• General good practices in handling food.

Vaccinations

• Vaccines use weakened or inactive forms of the virus to stimulate immunity without causing the disease.

• Example: Cowpox used for smallpox vaccination—immunization for the related version.

Immune Response

• Cells Involved:

  • White blood cells, B cells, and T cells are essential for combating infections.

• Antibodies: Produced by B cells to neutralize or mark pathogens for destruction.

Vaccination Effectiveness

• Vaccines can help prepare the immune system by creating a memory response against specific pathogens.

• Key focus on keeping vaccinations updated to maintain immunity against diseases such as measles and polio.

Historical Context and Impact of Infectious Diseases

Infectious Disease Statistics

• Discussion on mortality rates from infectious diseases over time—decreasing due to vaccinations, improved hygiene, and better living conditions.

• Importance of education and community hygiene in reducing disease rates.

R-Naught Value

• Refers to the contagiousness of a virus; for example,

  • R-naught of 2 means each infected person can potentially infect two others.

  • Mumps has a notably high R-naught value, emphasizing its ease of spread before widespread vaccination occurred.

Closing Thoughts

• Disease prevention hinges on understanding transmission methods, maintaining hygiene, and prioritizing vaccinations, particularly in light of recent dips in vaccination rates leading to resurgences of past diseases.