What are the symptoms of streptococcosis in chickens? Detailed explanation of prevention and treatment methods

Streptococcosis in chickens is an acute septicemic or chronic infectious disease of chickens. Both chicks and adult chickens can be infected, and it mostly occurs as an endemic. It is characterized by lethargy, persistent diarrhea, lameness and paralysis, and sometimes neurological symptoms. Cases in chickens, ducks, geese and pigeons have been reported in China, causing a considerable number of deaths among diseased birds and resulting in relatively large economic losses. Below is an introduction to the onset symptoms and prevention and treatment methods of streptococcosis in chickens.

1. Onset symptoms of streptococcosis in chickens

1. Acute type: manifested as septicemia symptoms. Sudden onset; diseased birds are listless, drowsy or in a lethargic state, have reduced or completely lost appetite, ruffled and dull feathers, and a purple or pale comb and wattles; sometimes swelling of the wattles is also seen. Diseased chickens have diarrhea, discharging pale yellow or grayish-green loose droppings. Adult birds show a decline in or cessation of egg production. The acute course lasts 1 to 5 days.

2. Chronic type: the course is relatively slow; diseased birds are in poor spirits, have reduced appetite, are drowsy, and in severe cases are lethargic, prefer to squat, and tuck their heads under their wings or into the feathers on their backs. They lose weight, become emaciated, are lame, have head tremors, or lie on their backs with the beak pointing upward; some diseased chickens have mild leg paralysis and cannot stand up. Some diseased chickens develop ophthalmia and keratitis. The conjunctiva becomes inflamed, swollen, and watery, with fibrinous inflammation covered by a layer of fibrinous membrane. In severe cases it can cause blindness.

2. Necropsy features of streptococcosis in chickens

1. Acute: subcutaneous and serosal muscular edema, fibrinous pericarditis, yolk peritonitis, and catarrhal enteritis. The liver, spleen, and kidneys are enlarged, with hemorrhagic spots and necrosis. The lungs are congested or edematous. The air sacs are cloudy and thickened.

2. Chronic: fibrinous pericarditis and perihepatitis. The parenchymal organs (myocardium, liver, spleen) show inflammation, degeneration, or infarction. There is tenosynovitis, fibrinous arthritis, salpingitis, and yolk peritonitis. Diseased birds are highly emaciated, and abscesses form between the mandibles.

3. Chicks: poor yolk absorption, enlarged and soft liver, yellowish-brown, enlarged gallbladder, hemorrhage in the cecal tonsils, and fibrinous pericarditis and meningeal congestion and hemorrhage.

3. Prevention and treatment methods for streptococcosis in chickens

1. Prevention: For prevention, the main measures are to strengthen feeding management, reduce all stress factors, enhance the immunity of the chickens, and strengthen sanitation and disinfection management. Using formaldehyde to disinfect the hatchery room can greatly reduce the occurrence of streptococcosis.

2. Treatment: For chickens with acute and subacute infection, drugs such as penicillin, gentamicin, tetracycline, and oxytetracycline can be selected for treatment. It has been reported that enrofloxacin has a very good curative effect on streptococcosis. Because streptococci can also develop drug resistance, it is best to base medication on the results of drug sensitivity tests.

4. Differential diagnosis of similar diseases of streptococcosis in chickens

1. Colibacillosis: The symptoms and lesions are diverse (chick encephalitis, yolk peritonitis, airsacculitis, arthritis, ophthalmia, Escherichia coli granuloma, septicemia, etc.). Microscopic examination shows Gram-negative, non-spore-forming small bacilli with peritrichous flagella and bluntly rounded ends.

2. Avian paratyphoid: Diseased chickens increase water intake, pass white watery droppings, and fear cold and prefer to stay near heat sources. Necropsy shows striped hemorrhagic spots or pinpoint-sized necrotic foci in the liver, spleen, and kidneys, and hemorrhagic inflammation of the small intestine. Microscopic examination shows Gram-negative, slightly rounded at both ends, slender bacilli.

3. Staphylococcosis: Trauma infection is obvious, lameness (tarsal and metatarsal arthritis), and there is a large amount of purplish-black blood-like exudate or purplish-red jelly-like material under the skin of the chest and abdomen (“big navel”). Microscopic examination shows Gram-positive cocci clustered in grape-like bunches.

4. Fowl cholera: The comb and wattles of diseased chickens are dark purple. Necropsy shows hemorrhage in the coronary fat and epicardium of the heart, and many grayish-white small necrotic spots on the surface of the liver. Microscopic examination shows Gram-negative, bipolar-staining, round small bacilli.