Lecture 5 Theme Pathogenesis in parasitic diseases

Lecture № 5 Theme: Pathogenesis in parasitic diseases. Epidemiology of the parasitic disease. Basis for the prevention of parasitic disease. The main activities to protect farms from parasitic diseases. The teachings of academician K. I. Skryabin on devastacy. D. Assylkhanov Senior lecturer, Dpt. Of “Biological safety”

The purpose of lecture: Epidemiological studies of parasitic diseases in animals. Organize and conduct preventive and control measures against parasitic diseases in animals Plan of the lecture: 1. Epidemiology of the parasitic disease. 2. Basis for the prevention of parasitic disease. The main activities to protect farms from parasitic diseases. 3. The teachings of academician K. I. Skryabin on devastacy

1. Epidemiology of the parasitic disease Epidemiological factors in helminth infection include the environmental factors like temperature, rain, soil type play major role for transmission parasites. Age, sex and breeds of domestic and wild animals an important aspect in epidemiology.

1. Epidemiology of the parasitic disease In order for infection and disease to occur in an individual, a process involving six related components must occur. This process has been referred to as the “Chain of Infection”. The six steps or “links” in the chain are: 1. Etiologic agent 2. Reservoir 3. Portal of Exit 4. Mode of Transmission 5. Portal of Entry 6. Susceptible Host

1. Epidemiology of the parasitic disease 1. Etiologic agent. There are seven categories of biological agents that can cause parasitic diseases. Each has its own particular characteristics. The types of agents are: 1. Metazoa; 2. Protozoa; 3. Fungi; 4. Bacteria; 5. Rickettsia; 6. Viruses and 7. Prions. Metazoa are multicellular animals, many of which are parasites. 2. Reservoirs. The next essential link in the chain of infection is the reservoir, the usual habitat in which the agent lives and multiplies. Depending upon the agent, the reservoir may be: • humans, • animals, and/or • environment

1. Epidemiology of the parasitic disease 3. Portal of Exit. The next link in the chain of disease transmission is the portal of exit, the route by which the disease agent may escape from the human or animal reservoir. While many disease agents have only one portal of exit, others may leave by various portals. The portals most commonly associated with human and animal diseases are: Respiratory Genitourinary Alimentary Skin Superficial lesions Percutaneous Transplacental.

1. Epidemiology of the parasitic disease 4. Mode of Transmission. The next link in the chain of disease transmission is the portal of exit, the route by which the disease agent may escape from the human or animal reservoir. While many disease agents have only one portal of exit, others may leave by various portals. The portals most commonly associated with human and animal diseases are: Respiratory Genitourinary Alimentary Skin Superficial lesions Percutaneous Transplacental.

1. Epidemiology of the parasitic disease 4. Mode of Transmission. A mode of transmission is necessary to bridge the gap between the portal of exit from the reservoir and the portal of entry into the host. The two basic modes are a) direct and b) indirect. a) Direct transmission occurs more or less immediately. Many diseases are transmitted by direct contact with the human, animal or environmental reservoir. b) Indirect transmission may occur through animate or inanimate mechanisms. • Animate mechanisms involve vectors. Inanimate mechanisms: When disease agents are spread by environmental vehicles or by air, this is referred to as indirect transmission by inanimate mechanisms. Anything may be a vehicle, including objects, food, water, milk, or biological products.

1. Epidemiology of the parasitic disease 5. Portals of Entry. The portal of entry into the host is usually the same as the portal of exit from the reservoir. 6. Susceptible Host. The last essential component in the chain of infection is the susceptible host. Susceptibility is affected by: • Genetic factors • General resistance factors • Specific acquired immunity 1. Genetic factors The role of genetic factors in susceptibility to infectious diseases is not yet well understood. 2. General resistance factors include many body functions that we take for granted. Intact skin and mucous membranes help us resist disease. So do the gastric acid in our stomachs, the cilia in our respiratory tracts, and the cough reflex. 3. Specific acquired immunity is the greatest influence on host susceptibility. This immunity is specific to a particular disease agent, and it may be acquired naturally or artificially

1. Epidemiology of the parasitic disease Age susceptibilities. Differences in susceptibility to disease are often seen between different age groups. For example, young animals are generally less susceptible to tick-borne diseases than older animals. Sex associations in disease In these associations the clinical signs of disease are associated with sexual attributes, as in the case of diseases of the reproductive tract, rather than with the fact that males may be more susceptible than females or vice versa.

2. Basis for the prevention of parasitic disease. The main activities to protect farms from parasitic diseases. Prevention and Control measures fall into the following control strategies: 1) Housing management; 2) Nutritional management; 3) Grazing management; 4) Biological Control; 5) Chemotherapy and Isolation; 6) Anthelminthic drugs management strategies and 7) Prophylactic vaccination and 8) Meat inspection. 1) Housing management. The animal should not be fed on the ground. Feeders, which cannot easily be contaminated with faeces, should be utilized for grain, hay, and minerals feeding. Water should be clean, and free from animals, birds, swine and dogs manure.

2. Basis for the prevention of parasitic disease. The main activities to protect farms from parasitic diseases. 2) Nutritional management. Animals, birds, swine and dogs must have a balanced diet, which include vitamins (Vitamin A, D and B), minerals and other nutrients. 3) Grazing management. The clean or new pastures are those pastures, which have not been grazed since 6– 12 months 4) Biological Control (Nematophagous Fungi). Fungi occur in the soil throughout the world where they feed on a variety of free-living soil nematodes. 5) Chemotherapy and Isolation. It is use to prevent the spread of infection and eliminate intermediate and reservoir hosts. 6) Anthelminthic drugs management strategies. a) Reduce use of anthelminthic drugs. Anthelminthic drugs (de-worm) are use to control in animal, bird, swine and dog helminth infection. b) Alternative dewormers.

The teachings of academician K. I. Skryabin on devastacy In 1944 K. I Skryabin was nominated by the principle of devastation, which stands for the total elimination of helminth as a species in the country. In 1947, K. I Skryabin devastation defines as “active offensive method of prevention for extermination, the physical destruction of pathogens in all phases of their life cycle, all available means of mechanical, chemical, physical and biological impacts”. Devastation - it is included as a main constituent of both therapy and in prevention and still have their specific tasks: physical destruction of pathogenic organisms in nature, regardless of the environmental conditions in which they are located and in which the biological stage of dwell.