Communicable diseases study guide

Communicable diseases study guide overview: this guide is anchored to Communicable (infectious) diseases, Viral diseases, Bacterial diseases, Fungal diseases, Protist diseases, Human defence systems, Vaccination, Antibiotics and painkillers, and Discovery and development of drugs. Use it to connect the published learning objectives with question practice, key terms, common mistakes, and exam tips for this topic.

Communicable (infectious) diseases checklist

• Define pathogens as microorganisms that cause infectious disease.
• State that pathogens may be viruses, bacteria, protists or fungi.
• Explain that pathogens may infect plants or animals.
• Explain that pathogens can spread by direct contact, by water or by air.
• Explain how diseases caused by viruses, bacteria, protists and fungi are spread in animals and plants.
• Explain how the spread of diseases can be reduced or prevented.

Viral diseases checklist

• Describe measles as a viral disease that causes fever and a red skin rash.
• Explain that measles is a serious illness that can be fatal if complications arise.
• Explain why most young children are vaccinated against measles.
• Explain that the measles virus is spread by inhalation of droplets from coughs and sneezes.
• Describe HIV as a viral disease that initially causes a flu-like illness.
• Explain that HIV attacks the body's immune cells and can lead to late-stage infection or AIDS if not controlled.

Bacterial diseases checklist

• Explain that salmonella food poisoning is spread by bacteria ingested in food or on food prepared in unhygienic conditions.
• Explain that poultry are vaccinated against salmonella in the UK to control the spread.
• Describe salmonella symptoms including fever, abdominal cramps, vomiting and diarrhoea.
• Explain that salmonella symptoms are caused by the bacteria and the toxins they secrete.
• Describe gonorrhoea as a sexually transmitted bacterial disease with pain on urinating and a thick yellow or green discharge.
• Explain that gonorrhoea was once easily treated with penicillin but resistant strains are now common.

Fungal diseases checklist

• Identify rose black spot as a fungal disease of plants.
• Describe rose black spot as causing purple or black spots on leaves.
• Explain that infected leaves often turn yellow and fall early.
• Explain that rose black spot reduces photosynthesis and affects plant growth.
• Explain that rose black spot spreads by water or wind and can be treated with fungicides or by removing and destroying affected leaves.

Protist diseases checklist

• State that the pathogens that cause malaria are protists.
• Explain that the malarial protist has a life cycle that includes the mosquito.
• Describe malaria as causing recurrent episodes of fever.
• Explain that malaria can be fatal.
• Explain that malaria is controlled by preventing mosquitos from breeding and by using mosquito nets to avoid bites.

Human defence systems checklist

• Describe the skin as a non-specific defence system against pathogens.
• Describe the nose as a non-specific defence system against pathogens.
• Describe the trachea and bronchi as non-specific defence systems against pathogens.
• Describe the stomach as a non-specific defence system against pathogens.
• Explain the role of the immune system in the defence against disease.
• Explain that if a pathogen enters the body the immune system tries to destroy it.

Vaccination checklist

• Explain how vaccination can prevent illness in an individual.
• Explain how vaccinating a large proportion of the population reduces the spread of pathogens.
• Explain that vaccination introduces small quantities of dead or inactive pathogen into the body.
• Explain that vaccination stimulates white blood cells to produce antibodies and enables a faster response if the pathogen re-enters the body.
• Evaluate the global use of vaccination in the prevention of disease.

Antibiotics and painkillers checklist

• Explain the use of antibiotics and other medicines in treating disease.
• Explain that antibiotics such as penicillin help to cure bacterial disease by killing infective bacteria inside the body.
• Explain why specific bacteria should be treated by specific antibiotics.
• Explain how antibiotics have greatly reduced deaths from infectious bacterial diseases.
• Explain why the emergence of antibiotic-resistant strains is a major concern.
• Explain that antibiotics cannot kill viral pathogens.

Discovery and development of drugs checklist

• Describe the process of discovery and development of new medicines, including preclinical and clinical testing.
• Explain that traditional drugs were extracted from plants and microorganisms.
• Recall that the heart drug digitalis originates from foxgloves.
• Recall that the painkiller aspirin originates from willow.
• Recall that penicillin was discovered by Alexander Fleming from the Penicillium mould.
• Explain that most new drugs are synthesised by chemists in the pharmaceutical industry.

Communicable diseases study guide overview: this guide is anchored to Communicable (infectious) diseases, Viral diseases, Bacterial diseases, Fungal diseases, Protist diseases, Human defence systems, Vaccination, Antibiotics and painkillers, and Discovery and development of drugs. Use it to connect the published learning objectives with question practice, key terms, common mistakes, and exam tips for this topic.

Communicable (infectious) diseases checklist

• Define pathogens as microorganisms that cause infectious disease.
• State that pathogens may be viruses, bacteria, protists or fungi.
• Explain that pathogens may infect plants or animals.
• Explain that pathogens can spread by direct contact, by water or by air.
• Explain how diseases caused by viruses, bacteria, protists and fungi are spread in animals and plants.
• Explain how the spread of diseases can be reduced or prevented.

Viral diseases checklist

• Describe measles as a viral disease that causes fever and a red skin rash.
• Explain that measles is a serious illness that can be fatal if complications arise.
• Explain why most young children are vaccinated against measles.
• Explain that the measles virus is spread by inhalation of droplets from coughs and sneezes.
• Describe HIV as a viral disease that initially causes a flu-like illness.
• Explain that HIV attacks the body's immune cells and can lead to late-stage infection or AIDS if not controlled.

Bacterial diseases checklist

• Explain that salmonella food poisoning is spread by bacteria ingested in food or on food prepared in unhygienic conditions.
• Explain that poultry are vaccinated against salmonella in the UK to control the spread.
• Describe salmonella symptoms including fever, abdominal cramps, vomiting and diarrhoea.
• Explain that salmonella symptoms are caused by the bacteria and the toxins they secrete.
• Describe gonorrhoea as a sexually transmitted bacterial disease with pain on urinating and a thick yellow or green discharge.
• Explain that gonorrhoea was once easily treated with penicillin but resistant strains are now common.

Fungal diseases checklist

• Identify rose black spot as a fungal disease of plants.
• Describe rose black spot as causing purple or black spots on leaves.
• Explain that infected leaves often turn yellow and fall early.
• Explain that rose black spot reduces photosynthesis and affects plant growth.
• Explain that rose black spot spreads by water or wind and can be treated with fungicides or by removing and destroying affected leaves.

Protist diseases checklist

• State that the pathogens that cause malaria are protists.
• Explain that the malarial protist has a life cycle that includes the mosquito.
• Describe malaria as causing recurrent episodes of fever.
• Explain that malaria can be fatal.
• Explain that malaria is controlled by preventing mosquitos from breeding and by using mosquito nets to avoid bites.

Human defence systems checklist

• Describe the skin as a non-specific defence system against pathogens.
• Describe the nose as a non-specific defence system against pathogens.
• Describe the trachea and bronchi as non-specific defence systems against pathogens.
• Describe the stomach as a non-specific defence system against pathogens.
• Explain the role of the immune system in the defence against disease.
• Explain that if a pathogen enters the body the immune system tries to destroy it.

Vaccination checklist

• Explain how vaccination can prevent illness in an individual.
• Explain how vaccinating a large proportion of the population reduces the spread of pathogens.
• Explain that vaccination introduces small quantities of dead or inactive pathogen into the body.
• Explain that vaccination stimulates white blood cells to produce antibodies and enables a faster response if the pathogen re-enters the body.
• Evaluate the global use of vaccination in the prevention of disease.

Antibiotics and painkillers checklist

• Explain the use of antibiotics and other medicines in treating disease.
• Explain that antibiotics such as penicillin help to cure bacterial disease by killing infective bacteria inside the body.
• Explain why specific bacteria should be treated by specific antibiotics.
• Explain how antibiotics have greatly reduced deaths from infectious bacterial diseases.
• Explain why the emergence of antibiotic-resistant strains is a major concern.
• Explain that antibiotics cannot kill viral pathogens.

Discovery and development of drugs checklist

• Describe the process of discovery and development of new medicines, including preclinical and clinical testing.
• Explain that traditional drugs were extracted from plants and microorganisms.
• Recall that the heart drug digitalis originates from foxgloves.
• Recall that the painkiller aspirin originates from willow.
• Recall that penicillin was discovered by Alexander Fleming from the Penicillium mould.
• Explain that most new drugs are synthesised by chemists in the pharmaceutical industry.

Communicable diseases study guide overview: this guide is anchored to Communicable (infectious) diseases, Viral diseases, Bacterial diseases, Fungal diseases, Protist diseases, Human defence systems, Vaccination, Antibiotics and painkillers, and Discovery and development of drugs. Use it to connect the published learning objectives with question practice, key terms, common mistakes, and exam tips for this topic.

Communicable (infectious) diseases checklist

• Define pathogens as microorganisms that cause infectious disease.
• State that pathogens may be viruses, bacteria, protists or fungi.
• Explain that pathogens may infect plants or animals.
• Explain that pathogens can spread by direct contact, by water or by air.
• Explain how diseases caused by viruses, bacteria, protists and fungi are spread in animals and plants.
• Explain how the spread of diseases can be reduced or prevented.

Viral diseases checklist

• Describe measles as a viral disease that causes fever and a red skin rash.
• Explain that measles is a serious illness that can be fatal if complications arise.
• Explain why most young children are vaccinated against measles.
• Explain that the measles virus is spread by inhalation of droplets from coughs and sneezes.
• Describe HIV as a viral disease that initially causes a flu-like illness.
• Explain that HIV attacks the body's immune cells and can lead to late-stage infection or AIDS if not controlled.

Bacterial diseases checklist

• Explain that salmonella food poisoning is spread by bacteria ingested in food or on food prepared in unhygienic conditions.
• Explain that poultry are vaccinated against salmonella in the UK to control the spread.
• Describe salmonella symptoms including fever, abdominal cramps, vomiting and diarrhoea.
• Explain that salmonella symptoms are caused by the bacteria and the toxins they secrete.
• Describe gonorrhoea as a sexually transmitted bacterial disease with pain on urinating and a thick yellow or green discharge.
• Explain that gonorrhoea was once easily treated with penicillin but resistant strains are now common.

Fungal diseases checklist

• Identify rose black spot as a fungal disease of plants.
• Describe rose black spot as causing purple or black spots on leaves.
• Explain that infected leaves often turn yellow and fall early.
• Explain that rose black spot reduces photosynthesis and affects plant growth.
• Explain that rose black spot spreads by water or wind and can be treated with fungicides or by removing and destroying affected leaves.

Protist diseases checklist

• State that the pathogens that cause malaria are protists.
• Explain that the malarial protist has a life cycle that includes the mosquito.
• Describe malaria as causing recurrent episodes of fever.
• Explain that malaria can be fatal.
• Explain that malaria is controlled by preventing mosquitos from breeding and by using mosquito nets to avoid bites.

Human defence systems checklist

• Describe the skin as a non-specific defence system against pathogens.
• Describe the nose as a non-specific defence system against pathogens.
• Describe the trachea and bronchi as non-specific defence systems against pathogens.
• Describe the stomach as a non-specific defence system against pathogens.
• Explain the role of the immune system in the defence against disease.
• Explain that if a pathogen enters the body the immune system tries to destroy it.

Vaccination checklist

• Explain how vaccination can prevent illness in an individual.
• Explain how vaccinating a large proportion of the population reduces the spread of pathogens.
• Explain that vaccination introduces small quantities of dead or inactive pathogen into the body.
• Explain that vaccination stimulates white blood cells to produce antibodies and enables a faster response if the pathogen re-enters the body.
• Evaluate the global use of vaccination in the prevention of disease.

Antibiotics and painkillers checklist

• Explain the use of antibiotics and other medicines in treating disease.
• Explain that antibiotics such as penicillin help to cure bacterial disease by killing infective bacteria inside the body.
• Explain why specific bacteria should be treated by specific antibiotics.
• Explain how antibiotics have greatly reduced deaths from infectious bacterial diseases.
• Explain why the emergence of antibiotic-resistant strains is a major concern.
• Explain that antibiotics cannot kill viral pathogens.

Discovery and development of drugs checklist

• Describe the process of discovery and development of new medicines, including preclinical and clinical testing.
• Explain that traditional drugs were extracted from plants and microorganisms.
• Recall that the heart drug digitalis originates from foxgloves.
• Recall that the painkiller aspirin originates from willow.
• Recall that penicillin was discovered by Alexander Fleming from the Penicillium mould.
• Explain that most new drugs are synthesised by chemists in the pharmaceutical industry.

Communicable Diseases

Communicable diseases, also known as infectious diseases, are illnesses caused by pathogens that can be transmitted from one individual to another. Understanding these diseases is crucial for preventing their spread and managing public health.

Pathogens

Pathogens are microorganisms that cause infectious diseases. They can be classified into four main types:

• Viruses: These are tiny infectious agents that can only replicate inside the living cells of an organism. They cause diseases such as measles and HIV.
• Bacteria: These are single-celled organisms that can reproduce rapidly inside the body. Some bacteria are beneficial, while others can produce toxins that damage tissues and cause illness, such as in the case of salmonella.
• Protists: These are a diverse group of microorganisms, some of which can cause diseases like malaria.
• Fungi: These organisms can also be pathogens, with examples like the tobacco mosaic virus affecting plants.

Transmission of Pathogens

Pathogens can spread through various means:

• Direct Contact: This includes physical interaction between individuals, such as touching or sexual contact.
• Water: Contaminated water can be a medium for pathogens, leading to diseases like cholera.
• Air: Many viral infections, such as the flu and measles, spread through airborne droplets from coughs or sneezes.

Understanding how these pathogens spread is essential for implementing effective prevention strategies.

Spread of Diseases

Viral Diseases

• Measles: This viral disease is characterized by fever and a red skin rash. It can be serious and even fatal if complications arise. Vaccination is crucial for young children to prevent measles, which spreads through inhalation of droplets from coughs and sneezes.
• HIV: This virus attacks the immune system and can lead to AIDS if not controlled. It spreads through sexual contact or the exchange of body fluids, such as blood from shared needles.
• Tobacco Mosaic Virus: Affects many plant species, including tomatoes, causing a mosaic pattern of leaf discoloration that reduces photosynthesis and plant growth.

Bacterial Diseases

• Salmonella: This bacterium causes food poisoning, often spread through contaminated food. Symptoms include fever, abdominal cramps, vomiting, and diarrhea. In the UK, poultry are vaccinated against salmonella to control its spread.
• Gonorrhoea: A sexually transmitted bacterial disease characterized by pain during urination and discharge. It was once easily treated with penicillin, but resistant strains are now common. Gonorrhoea spreads through sexual contact, and its spread can be controlled with antibiotics and barrier contraception.

Fungal Diseases

• Rose Black Spot: A fungal disease affecting plants, causing purple or black spots on leaves. Infected leaves may turn yellow and fall early, reducing photosynthesis and plant growth. This disease spreads by water or wind and can be treated with fungicides or by removing affected leaves.

Protist Diseases

• Malaria: Caused by protists, malaria leads to recurrent episodes of fever and can be fatal. It is transmitted through mosquitoes, and control measures include preventing mosquito breeding and using nets to avoid bites.

Human Defence Systems

The human body has several non-specific defence mechanisms against pathogens:

• Skin: Acts as a barrier to prevent pathogens from entering the body.
• Nose: Filters and traps pathogens in mucus.
• Trachea and Bronchi: Have cilia and mucus to trap and expel pathogens.
• Stomach: Produces acid that kills many pathogens.

When a pathogen enters the body, the immune system responds by trying to destroy it. White blood cells play a crucial role in this defence:

• Phagocytosis: White blood cells engulf and digest pathogens.
• Antibody Production: White blood cells produce antibodies that specifically target pathogens.
• Antitoxin Production: White blood cells can also produce antitoxins to neutralize toxins produced by bacteria.

Vaccination

Vaccination is a vital public health tool that helps prevent illness. It works by introducing small quantities of dead or inactive pathogens into the body, stimulating the immune system to produce antibodies. This prepares the body for a faster response if the pathogen is encountered again. Vaccinating a large proportion of the population can significantly reduce the spread of diseases.

Antibiotics and Painkillers

Antibiotics are crucial in treating bacterial infections by killing infective bacteria inside the body. However, they are ineffective against viral pathogens. The emergence of antibiotic-resistant strains is a major concern, highlighting the need for careful use of antibiotics. Painkillers, on the other hand, treat symptoms of diseases but do not kill pathogens.

Discovery and Development of Drugs

The process of discovering and developing new medicines involves several stages, including preclinical and clinical testing. Traditional drugs were often derived from plants and microorganisms. For example, digitalis originates from foxgloves, and aspirin comes from willow. New drugs must undergo rigorous testing for safety and efficacy before they can be approved for use.

In conclusion, understanding communicable diseases, their transmission, and the body's defence mechanisms is essential for managing health and preventing outbreaks. Vaccination and responsible use of antibiotics are key strategies in combating infectious diseases.