Sex and - PowerPoint Presentation

Slide1

Sex and behaviour:Immune response to parasites

CfE

Advanced Higher Biology

Unit

2:

Organisms and EvolutionSlide2

SQA mandatory key areaNon-specific defenses in mammals: physical barriers, chemical secretions, inflammatory response, phagocytes, natural killer cells destroying abnormal cells. Mechanism of specific cellular defenses in mammals: apoptosis, phagocytosis, T lymphocytes, B lymphocytes and immunological memory cells. Epidemiology and herd immunity. The herd immunity threshold is the density of resistant hosts in the population required to prevent an epidemic. Endoparasites and antigenic variation. Slide3

Key concepts 1Specific cellular defence in mammals involves immune surveillance by white blood cells, clonal selection of T lymphocytes, T lymphocytes targeting immune response and destroying infected cells by inducing apoptosis, phagocytes presenting antigens to B lymphocytes, the clonal selection of B lymphocytes, production of specific antibody by B lymphocyte clones, long term survival of some members of T and B lymphocyte clones to act as immunological memory cells. Slide4

Key concepts 2Epidemiology is the study of the outbreak and spread of infectious disease. Endoparasites mimic host antigens to evade detection by the immune system, and modify host-immune response to reduce their chances of destruction.Antigenic variation in some parasites allows them to evolve fast enough for them to be one step ahead of host immune cell clonal selection. Slide5

Classification of microbes

Algae

Fungi

Bacteria

Protozoa

Viruses

E.coli

Giardia

Cold /flu

Trichophyton-ATHLETES FOOTSlide6

EndoparasitesThose that live inside the host are called endoparasites (including all parasitic worms). Endoparasites can exist in one of two forms: intercellular parasites (inhabiting spaces in the host’s body) or intracellular parasites (inhabiting cells in the host’s body). Intercellular parasite – Legionella (Legionnaires disease)Intracellular parasites - Plasmodium (Malaria)Slide7

Pathogens and disease

Infectious disease is a major cause of death worldwide.

It is estimated that 14.7 million people died in 2002 due to infectious diseases.

An

infectious disease

is a disease resulting from infection of a host organism by a

pathogen

, a disease-causing organism.

There are several different types of pathogen including

bacteria

,

fungi

, viruses and parasites. Slide8

Transmission – short taskSelect one of the following diseases to study:Athletes footCholeraGastroenteritis (caused by Campylobacter or Salmonella)HIVTuberculosisMalaria

Find out the following:

Transmission method

Type of

microorganism

Symptoms

Prevention/treatment

Present your findings to the classSlide9

Control of diseaseQuarantineAntisepsis (prevent disease infection through inhibition or arresting the areas of growth of the infection).Individual responsibility (good hygiene, care in sexual health and appropriate storage/handling of food), Community responsibility (quality water supply, safe food webs and appropriate waste disposal systems) Control of vectorsSlide10

EpidemiologyIs the study of the outbreak and pattern of infectious diseases to determine the factors which affect their spread.Slide11

Outbreaks of disease can occur on different levels:sporadic – (occasional occurrence) the disease occurring occasionally, singly or in scattered instances. endemic – (regular cases occurring in an area) it is continually present in a population but at a low level (for example the common cold). epidemic – (unusually high number of cases in an area )it has suddenly increased above the normal endemic level and infects many people. pandemic – (a global epidemic ) it is epidemic over a very wide area (usually a continent or the world). Slide12

Depending on epidemiological studies, measures are considered to control the spread of diseases. preventing transmission drug therapy immunisationSlide13

Types of ImmunityActive immunity - antibodies made by individual in two ways:Natural Acquired Active – Antibodies made by individual in response to antigen Artificially Acquired - In response to vaccine.Passive immunity - antibodies given to individual in two ways

Natural - Ingested with milk shortly after birth

Acquired – injection of antibodies to combat a disease e.g. rabiesSlide14

Active immunity Antigens usually mixed with an adjuvant to form the active vaccine and enhance the immune response.Vaccines include: inactivated pathogen toxins dead pathogens parts of pathogens weakened pathogens.Slide15

Antibody responses

Memory

cells

– lymphocytes specific to antigen from first exposure to it.Slide16

Edward Jenner & the Small Pox VaccineUse this website: http://www.jenner.ac.uk/edwardjenner to find out about how Edward Jenner developed the Small Pox Vaccine.Write a short note including:When he did this workHow he linked cowpox and smallpoxHow he tested the vaccine When smallpox was eradicated.Slide17

The Independent - Thursday 22 May 2014 The General Assembly of the WHO will take a vote on Friday (23rd May) on whether to eradicate the variola virus completely and forever by ordering the incineration of stockpiles in Russia and the United States, which are kept under an agreement signed in 1983 when Ronald Reagan was US President and the Soviet Union was still a country. http://www.independent.co.uk/news/science/health-experts-to-vote-on-whether-to-destroy-the-last-few-samples-of-smallpox-9412451.htmlSlide18

Any further news?Search online for smallpox to find out!Slide19

Herd ImmunityThe herd immunity threshold depends on:The diseaseThe efficacy (effectiveness) of the vaccineThe contact parameters for the population. Slide20

Pros

Difficulties

Protects

vulnerable and the non-vaccinated

The developing world-

vaccination is not possible due to malnutrition and poverty

Reducing

the spread of diseases

The developed world- vaccines are rejected by a percentage of the population.Slide21

The MMR controversy

In 1998, a scientific paper was published in the medical journal

The Lancet

, speculating that the

MMR

vaccine could cause autism.

The authors did not prove that this was the case but still recommended that doctors stop administering the

MMR

vaccine until more research was done.

The authors thought that the

MMR

vaccine could damage the bowel, allowing toxins that are normally destroyed in digestion to move into the blood. If these toxins travelled to the brain they might cause autism.Slide22

The media’s role in the MMR controversy

Many studies have concluded that the

MMR

vaccine is safe and only a few studies claim that it isn’t. However, this was not reflected by the

media coverage

.

The

majority of coverage centred on the possibility of a link between the

MMR

vaccine and autism, while the government insisted that the vaccine was safe. This mixed message caused confusion among the general public, leading to a drop in the number of children being given the combined vaccine. Should scientists be more careful about how they present their research or should the media be responsible for how they present controversial topics to society?

.Slide23

Antigenic variationMany pathogens like viruses, bacteria and protozoa can evolve mechanisms that evade the specific immune system of the human body and can affect vaccination strategies globally. Antigenic variation is a process by which a pathogen is able to change its surface proteins so that it can evade the host immune responses. Slide24

The antigenic profile will change as the pathogen passes through the host population or in the original infected host. Antigenic variation is particularly important for pathogens as it allows them to:- target hosts which are long-lived or susceptible to the pathogen- infect a single host on more than one occasion - transmit the disease easily. This drift results in small antigenic changes in the pathogen population and will reduce the efficacy of B and T cell memory during the host immune response. Slide25
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QuestionUse the information you have learned so far to explain why people need to be immunised against Influenza annually.