What are the prevention and control measures for swine high fever disease? A brief analysis by Nanjing Dafang (1)
A brief analysis by Nanjing Dafang of the prevention and control measures for swine high fever disease (1)
Part One: Pathogenesis of "swine high fever"
First, fever, that is, elevated body temperature, is a pathological process common to many diseases, especially infectious diseases. This means that many diseases can cause "high fever disease". Moderate fever can increase the phagocytic action of white blood cells and macrophages, which helps the body eliminate pathogenic microorganisms.
Then, during fever, because thyroid and adrenal secretion increase, the catabolism of sugar, protein and fat is strengthened (for every 1°C rise in body temperature, the metabolic rate increases by about 13%); at the same time, fever causes reduced appetite, reduced intake of nutrients, and massive consumption of nutrients in the body, causing metabolic disorders.
1. Glycogen decomposition is strengthened; severe acute fever may cause glycosuria, insufficient oxygen supply, increased lactic acid production, and muscle soreness.
2. Fat decomposition is significantly strengthened; when sugar intake is insufficient, excessive fat decomposition and incomplete oxidation occur, blood fatty acids and ketone bodies increase greatly, and in severe cases ketonemia and ketonuria form.
3. Protein decomposition increases, causing increased non-protein nitrogen in blood and urine; at the same time, because digestive function is reduced, protein intake and absorption decrease, causing negative nitrogen balance, which leads to degeneration and atrophy of muscles and parenchymal organs, and weakening of the body.
4. During fever, vitamin C and B vitamins are consumed significantly more; because appetite is reduced, intake is insufficient, often causing severe vitamin deficiency. Vitamin C is also called ascorbic acid; a large deficiency can increase capillary wall permeability and cause petechial hemorrhage.
5. Fever involves disturbances in water and salt metabolism, with reduced sodium and water excretion and increased potassium excretion, often causing hypokalemia. In addition, increased production of lactic acid and ketone bodies and reduced renal excretory function often cause acidosis.
The above metabolic changes are characteristics common to all febrile diseases, and are not the exclusive property of any one infectious disease.
Next, let us look at the changes in body functions during fever.
1. In the early stage of fever, some animals appear restless and agitated, while others appear depressed. In the peak stage of fever, due to the influence of high-temperature blood and toxic products, the central nervous system shows inhibition, the animals are depressed, and may even be in a comatose state.
2. Heartbeat accelerates, peripheral blood vessels constrict, and the burden on the heart increases; during fever caused by infectious diseases, the toxins of pathogenic microorganisms directly damage the myocardium, often causing heart failure, and destruction of endothelial cells in the walls of capillaries and small arteries, causing skin congestion and hemorrhage.
3. Breathing accelerates; during persistent high fever, the excitability of the respiratory center decreases, resulting in shallow breathing. Due to reduced resistance, pneumonia is often induced. Due to physical weakness, inability to stand up, and the effect of gravity, pulmonary congestive edema is caused.
4. Digestive juice secretion decreases, intestinal peristalsis weakens, appetite decreases, and water reabsorption is strengthened, often causing constipation, which in turn causes fermentation of intestinal contents and autointoxication, so that body temperature remains persistently high.