(7) Examples of viral pathogen communicable diseases

(7a) Measles is a viral disease spread by droplets when an infected person sneezes or coughs.

The primary symptoms are a red skin rash and a higher than normal body temperature from a fever.

The measles virus causes a red, blotchy rash that usually appears first on the face and behind the ears and then spreads downward to the chest and back and finally to the feet.

Measles is a childhood infection caused by a virus, although once quite common, measles can now almost always be prevented with a vaccine (in the MMR 'jab').

Measles is treated by taking painkillers for any aches, pains or fever,  get plenty of rest, drinking plenty fluids and avoiding harsh light if your eyes hurt.

Measles virus infection can be a serious medical condition and even fatal if complications develop e.g. a lung infection like pneumonia or the brain infection encephalitis.

Most people are adequately protected if you are vaccinated when young.

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(7b) Chicken pox is caused by a virus - typical symptom is a spotty rash.

When a person has become infected with this viral pathogen, it takes nearly 14 days for the rash to appear, this time is called the incubation period.

The chicken pox virus cause an itchy blister-like rash and raised lumps on the skin - the blisters form scabs which eventually fall off.

Symptoms include aching joints, headache and cold-like symptoms such as a cough.

It is very contagious, but can be prevented by vaccination.

The patient needs to be isolated from people as much as is possible!

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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 chicken pox and measles

Viral Pathogens: Measles & Chickenpox

1. What Are Viral Pathogens?

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

• They replicate inside host cells, often destroying them in the process.

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

• Antibiotics do not work against viruses.

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Measles

Pathogen: Measles virus (a morbillivirus)

Transmission:

• Airborne droplets from coughs and sneezes.

• Highly contagious — can survive in the air or on surfaces for hours.

Symptoms:

• Fever

• Red skin rash (starts on face, spreads to body)

• Cough, runny nose, red/watery eyes

• Fatigue and irritability

Effects:

• Can lead to serious complications:

  • Pneumonia

  • Encephalitis (brain inflammation)

  • Blindness

• Can be fatal, especially in young children or those with weak immune systems.

Treatment:

• No specific antiviral cure.

• Supportive care: fluids, rest, painkillers (e.g. paracetamol).

• Isolation to prevent spread.

Prevention:

• MMR vaccine (Measles, Mumps, Rubella) — highly effective and essential, but not all get vaccinated!

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Chickenpox

Pathogen: Varicella-zoster virus (a herpesvirus)

Transmission:

• Airborne droplets or direct contact with fluid from blisters.

• Very contagious, especially in early stages.

Symptoms:

• Itchy, blister-like rash (starts on chest/back, spreads)

• Fever

• Fatigue

• Headache

• Loss of appetite

Effects:

• Usually mild in children.

• Can cause skin infections, pneumonia, or brain inflammation in severe cases.

• Virus can remain dormant and reactivate later in life as shingles.

Treatment:

• Supportive care: calamine lotion, antihistamines, rest, fluids.

• Antiviral drugs (e.g. acyclovir) in severe cases or for high-risk individuals.

Prevention:

• Varicella vaccine (available in some countries).

• Isolation during infectious period.

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Why Is This Important in Human Biology?

• Reinforces understanding of how viruses spread and affect the body.

• Highlights the role of the immune system in fighting infections.

• Emphasises the importance of vaccination in disease prevention.

• Links to public health, epidemic control, and global health awareness.

• Helps explain why antibiotics don’t work on viral infections.

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Quick Comparison Table

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Keywords, phrases and learning objectives for this part on the viral infections of chicken pox and measles

Be able to describe the viral pathogen diseases infections of the chicken pox virus and the measles virus.

Know they are very easily spread and know the symptoms of these communicable diseases.

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