Common diseases of poultry in summer and their prevention
Introduction
Poultry birds are generally affected by seasonal climatic or weather changes. For example, poultry gather together to produce heat and stay warm during wet or cold seasons and consume more feed and less water. However, to lower their body temperature during hot weather, poultry and other livestock drink more water and consume less feed. These changes affect laying birds, producing fewer eggs in exceptionally cold or hot weather. This reduction in egg production occurs when there are extreme cold or hot conditions; these birds are stressed and their ability to withstand diseases or their immune system is affected. In poultry production, heat stress plays a significant role, particularly in summer months.
Common diseases
1) Heat stress/Heat stroke: The primary issue was the absence of sweat glands, leading to panting, listlessness, reduced appetite, coma and death. Among growers, it will reduce growth rate whereas layer birds show smaller eggs, reduced growth and reduced quality.
2) Necrotic enteritis and coccidiosis: Heat stress damages intestinal integrity and alters microbiota, fostering bacteria and protozoa, which increase susceptibility to necrotic enteritis and coccidiosis. Necrotic enteritis is caused by Clostridium perfringens types A and C, gram-positive organisms. The birds may not show any clinical symptoms. Coccidiosis is one of the most important diseases of poultry worldwide, especially in the broiler industry, characterized by bloody diarrhoea and high mortality. 9 species of Eimeria have been identified. Eimeria tenella and Eimeria necatrix species are the most harmful among Eimeria species. Clinical signs show birds are pale, droopy, tend to huddle, consume less feed and water and have bloody diarrhoea.
3) Salmonellosis (Pullorum/Fowl Typhoid): High temperature can exacerbate these bacterial infections. Pullorum disease, also known as bacillary white diarrhea, is caused by Salmonella pullorum, a gram-negative, non-motile, rod-shaped organism. Chicks below 3 weeks of age are affected. Excessive numbers of dead-in-shell chicks and deaths soon after hatching. White viscous (thick and sticky) droppings sticking to the feathers around the vent were one of the most common clinical signs. Fowl typhoid was a septicemic disease affecting mainly chickens and turkeys. It is caused by Salmonella gallinarum, a gram-negative, non-motile bacterium. Clinical signs include an increase in mortality followed by a drop in feed consumption. Depression, ruffled feathers, and closure of eyes. Watery to mucoid yellow diarrhea was a characteristic sign.
4) Parasite Infestation: Mites, lice and flies thrive in summer, causing skin irritation and disease transmission. Summer heat accelerates the life cycle of mites, lice and ticks, which can further drain a bird’s energy and immunity. The most common mites are the poultry red mite (Dermanyssus gallinae), scaly leg mite (Knemidocoptes mutans), depluming mite (Neocnemidocoptes gallinae) and feather mites. Poultry red mites are non-burrowing mites are normally feed around the breast and legs, causing pain, irritation, decreased egg production and anemia. Pustules, scabs, hyper pigmentation and feather loss may develop. Scaly leg mites are burrowing mites causing thickening, crusts, raised scales and lameness found in older birds. The mite invades the skin under the scales, causing chronic dermatitis, which results in accumulation of exudates under the scales. The chicken body louse (Menacanthus stramineus) is the most common louse found on the skin, breast and thigh areas. Heavy infestations result in decreased fertility and egg production, decreased weight gain, skin irritation and secondary infections. The fowl tick (Argas persicus) is the most important tick among poultry because it acts as a transmission for avian spirochetosis.
Prevention and control
1) Heat stress/Heat stroke: Heat stress is fundamentally a failure of environmental control. Houses should be oriented east–west with adequate roof overhangs and thermal insulation to limit solar heat gain. High air speed at bird level (2–3 m/s) must be maintained through tunnels or cross-ventilation, well-maintained fans and evaporative cooling systems such as foggers or cooling pads. Stocking density should be reduced before peak summer and obstructions to airflow should be removed. Water management is equally critical. Birds dramatically increase water intake during heat stress, so drinker lines must be flushed regularly and cool water supplied throughout the day. Supplementing drinking water with electrolytes (Na⁺, K⁺, Cl⁻), vitamins C and E and betaine supports acid–base balance and antioxidant status. Feeding should be shifted to cooler hours late evening and early morning with dietary crude protein slightly reduced while maintaining digestible amino acid balance, thereby lowering the heat increment of feeding.
2) Necrotic enteritis and coccidiosis: Effective coccidiosis control is the corner stone of necrotic enteritis prevention, as mucosal damage caused by Eimeria creates a niche for Clostridium perfringens overgrowth. Control programs should combine ionophore or chemical anti-coccidials with live or attenuated vaccines in rotation, tailored to farm history and local drug-sensitivity patterns. High-risk dietary ingredients such as poorly processed fish meal and viscous cereals should be avoided or supplemented with exogenous enzymes (xylanases, beta-glucanases). Organic acids, including micro encapsulated butyrate, probiotics, and selected yeast fractions, have demonstrated protective effects against C. perfringens challenge and support intestinal barrier function. Litter quality must be actively managed through adequate ventilation, leak control around drinker lines, and prompt removal of caked material. Thorough house cleanout, washing, disinfection and a sufficient downtime period between flocks reduce the environmental load of both Eimeria oocysts and clostridial spores.
3) Salmonellosis (Pullorum Disease and Fowl Typhoid): Control begins at the breeder level through regular serological testing, culling of positive birds and strict hatchery hygiene to prevent vertical transmission. Egg sanitation, fumigation and incubation of eggs only from tested, clean flocks are essential. Farm-level bio-security controlling movement of people and equipment, rigorous rodent and insect control and dedicated clothing and footwear limits horizontal spread between the flocks.
4) Ectoparasite Infestations: Warm temperatures accelerate the life cycles of poultry red mites (Dermanyssus gallinae), lice, fowl ticks (Argas persicus) and flies, making summer a period of heightened ectoparasite risk. An integrated pest management approach is recommended: approved ecto-parasiticides applied judiciously, rotated to minimize resistance, combined with botanical alternatives such as tobacco dust and neem (Azadirachta indica), which have demonstrated efficacy in backyard and commercial settings. Houses should be thoroughly cleaned between flocks, cracks and crevices sealed and wild bird and rodent access minimized. Regular physical examination of birds and monitoring of perches and nest boxes allows early detection and prompt intervention.
