(9) Examples of viral pathogen communicable diseases

(9a) Ebola is caused by a virus causing a fever accompanied by bleeding (haemorrhagic fever).

Ebola haemorrhagic fever (EHF) is a deadly virus - 50-90% 0f infected people die.

Ebola is carried by fruit bats (the vector) and infect other animals and humans - unfortunately, in some parts of West Africa, fruit bat is considered a delicacy - a cultural barrier in reducing transmission.

Ebola spreads through human-to-human transmission via direct contact through broken skin or mucous membranes with the blood, secretions like saliva, organs or other bodily fluids of infected people, and with surfaces and materials (e.g. bedding, clothing) contaminated with these fluids.

Ebola symptoms include fever, headache, diarrhoea, nausea and rashes - typical observations of the effect on many pathogen infections.

Ebola causes haemorrhagic fever - where you bleed internally or from your eyes, mouth or nose.

Treatment of Ebola includes providing plenty of fluids and electrolytes (body salts) orally or through infusion into the vein (intravenously). Patients may also need medication to support blood pressure, reduce vomiting and diarrhea, and to manage fever and pain.

To reduce the spread of Ebola, infected people should be isolated and sterilising any areas where the virus might be, including hospital beds used by Ebola sufferers.

The safe burial of the victims of Ebola.

The spread and transmission of Ebola can be further reduced by ensuring ALL medical staff wash their hands frequently and wear protective clothing.

Other precautions include minimising risk of contact with infected animals.

Restricting travel between locations with Ebola outbreaks.

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(9b) Hepatitis

The hepatitis virus causes long-term infections in the liver where it lives in the cells.

Symptoms of hepatitis: jaundice (a yellowing of the skin and eyes), abdominal pain, loss of appetite, nausea and vomiting, diarrhea and fever.

Unfortunately, suffering from hepatitis, gives you an increased chance of developing liver cancer - a case of a communicable disease making you more susceptible to a non-communicable disease.

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See also Viruses - structure, reproduction and cell destruction

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Key points Source of information is based on textbooks & syllabus-specifications for students taking the AQA GCSE, Edexcel GCSE and OCR GCSE level biology examinations (~US grades 9-10).

Key points about the ebola virus and hepatitis virus

Revision notes on viral communicable diseases, specifically Ebola virus and Hepatitis viruses

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Viral Pathogen Diseases: Ebola and Hepatitis

1. What Are Viral Pathogens?

• Viruses are non-cellular pathogens made of genetic material (DNA or RNA) inside a protein coat.

• They replicate inside host cells, often destroying them.

• Viral diseases are communicable — they can spread from person to person.

• Antibiotics do not work against viruses.

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Ebola Virus Disease (EVD)

Pathogen: Ebola virus (a filovirus)

Transmission:

• Spread through direct contact with:

  • Bodily fluids (blood, vomit, sweat, saliva, urine)

  • Contaminated surfaces or clothing

  • Infected animals (e.g. fruit bats, primates)

• Not airborne, but highly contagious through fluid contact.

Symptoms:

• Sudden high fever

• Headache, muscle pain, weakness

• Vomiting, diarrhoea

• Internal and external bleeding (haemorrhagic fever)

• Rash and organ failure in severe cases

Effects:

• Rapid loss of fluids → shock and organ failure

• High fatality rate (50–90% in some outbreaks)

• Can overwhelm healthcare systems during outbreaks

Treatment:

• No specific cure, but supportive care is vital:

  • Rehydration with fluids and electrolytes

  • Oxygen therapy

  • Blood transfusions

• Experimental vaccines and antiviral drugs are being developed and used in high-risk areas.

Prevention:

• Isolation of infected individuals

• Protective clothing for healthcare workers

• Sterilisation of contaminated areas

• Ebola vaccine (e.g. rVSV-ZEBOV) for outbreak control

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Hepatitis Virus (Focus on Hepatitis B and C)

Pathogen: Hepatitis B virus (HBV) and Hepatitis C virus (HCV)

Transmission:

• Spread through blood and body fluids:

  • Unprotected sex

  • Sharing needles

  • Blood transfusions (if unscreened)

  • Mother to baby during birth

Symptoms:

• Often no symptoms in early stages

• When present:

  • Fatigue

  • Jaundice (yellowing of skin and eyes)

  • Abdominal pain

  • Dark urine

  • Nausea and vomiting

Effects:

• Liver inflammation (hepatitis)

• Can lead to chronic liver disease, cirrhosis, or liver cancer

• Hepatitis B is more likely to become chronic in infants and young children

Treatment:

• Hepatitis B:

  • No cure, but antiviral medications can manage the infection

  • Lifelong monitoring may be needed

• Hepatitis C:

  • Curable with modern antiviral drugs (e.g. direct-acting antivirals)

Prevention:

• Hepatitis B vaccine (routine in many countries)

• Safe sex practices

• Screening blood donations

• Avoiding needle sharing

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Why Is This Important in Human Biology?

• Shows how viruses affect different organs (e.g. liver, immune system).

• Highlights the importance of vaccination, hygiene, and public health measures.

• Reinforces understanding of immune response, disease transmission, and global health challenges.

• Encourages awareness of emerging diseases and the role of science in outbreak control.

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Quick Comparison Table

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Keywords, phrases and learning objectives for this part on the ebola virus and hepatitis virus

Know that ebola is a viral pathogen communicable disease, very easily spread by the fruit bat acting as a vector.

Know that the hepatitis virus causes a severe liver infection.

Know the symptoms and dangers of ebola and hepatitis communicable diseases.

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