Why does high relative humidity (> 80%) in litter trigger coccidiosis outbreaks in brown replacement pullets?

Coccidiosis is a devastating enteric disease caused by protozoan parasites of the genus Eimeria. The transmission cycle relies entirely on the ingestion of sporulated oocysts from the litter. Non-sporulated oocysts excreted in chicken manure are non-infectious; they require specific environmental conditions to "sporulate" (mature into an infectious state). When the relative humidity inside a pullet house exceeds 80% (due to poor ventilation, leaking drinker lines, or humid monsoon weather in Punjab), and litter temperatures range between 25°C and 30°C, it creates a highly active biological incubator. Under these conditions, Eimeria oocysts sporulate within 24 to 48 hours. When young brown pullets peck the damp litter, they ingest massive doses of these sporulated oocysts, which invade the intestinal enterocytes, causing mucosal hemorrhages, severe diarrhea, poor FCR, and high mortality. Maintaining dry, friable litter (humidity < 30%) through proper ventilation is critical. Farmers can study parasite lifecycles in the Poultry Encyclopedia, buy high-potency anticoccidial drugs on Poultry Plaza, track daily egg rates on Poultry Rates, and list healthy pullet flocks on Murghi Mandi.