EDS is often referred to as an invisible threat because the disease usually goes undetected until hens reach their laying age.

At first glance, a layer chicken house may appear completely normal. The hens eat well, remain active, and show no signs of mortality. However, egg production gradually begins to decline. The eggs produced become more fragile, dull in color, and some may even consist only of membranes without shells. This is the classic picture of Egg Drop Syndrome (EDS).

Through a written interview received on Tuesday (28/4), drh. Maulana Sydik, Vice President Poultry Health & Quality Assurance at PT Mitra Berlian Unggas, explained that EDS was first reported in the Netherlands in 1976 by van Eck and Davelaar. Ironically, further investigation revealed that the causative virus had already been spreading through vaccines used in many countries long before the disease was officially identified.

“That moment explains why EDS appeared simultaneously across various parts of the world. In reality, it was not appearing simultaneously, the virus was simply only identified later. Today, EDS is already endemic in Indonesia and has become one of the poultry diseases that all farmers must seriously guard against.”

Understanding Egg Drop Syndrome

EDS is a viral disease that attacks the reproductive system of laying hens. Simply put, the virus enters the shell gland, damages its function from within, and results in poor-quality eggs or even shell-less eggs. Egg production also drops sharply because the ovulation process is disrupted. The disease is caused by Duck Adenovirus type 1 (DAdV-1), also known as Atadenovirus.

“The term ‘duck’ is not just a name. The virus originally comes from ducks and geese, but it does not cause disease in their bodies. They can even carry the virus for life without becoming sick. But once the virus infects chickens, everything falls apart,” he explained.

According to Maulana, there are two main routes of EDS transmission: vertical and horizontal transmission, both of which are equally dangerous. Vertical transmission occurs through hatching eggs. Breeder hens carrying the virus can pass it on to their chicks. The chicks hatch in healthy condition, grow normally, pass through the pullet phase without any suspicious signs, and only when they start laying eggs does the virus become active and begin damaging production.

“This is what makes EDS difficult to detect early. There are no warning signs during the pullet phase. The chickens look healthy, eat well, and grow normally. We do not realize the virus is already inside them until the first signs of production problems appear.”

Meanwhile, horizontal transmission occurs through direct contact with infected birds, feces, secretions, or contaminated equipment. Wild ducks and geese roaming around poultry houses are among the most common sources of horizontal transmission.

“It can also spread through vehicles that are not disinfected, workers moving from one poultry house to another, or equipment used interchangeably. All of these can become invisible vectors of disease transmission. In the past, contamination in live vaccines also contributed to the spread of EDS. However, standards today are much stricter, reducing the risk significantly,” he said.

Recognizing the Symptoms of EDS

Identifying early symptoms is one of the most important steps in suppressing disease spread. Most farmers only realize there is a problem after egg production has already dropped significantly. In fact, there are early warning signs that can be detected sooner, provided farmers know what to observe, such as changes in shell color and shells becoming thinner and softer.

This article is an excerpt from the Health section of Poultry Indonesia magazine, May 2026 edition. Read the full article in Poultry Indonesia Magazine May 2026 Edition. For subscriptions or further information, contact: https://wa.me/+6287780120754 or sirkulasipoultry@gmail.com

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