Infectious Coryza in Chickens: Swollen Face, Runny Nose, Diagnosis and What Farmers Should Do

If your chickens are sneezing, have watery or sticky discharge from the nose, and the face or area around the eyes starts swelling, infectious coryza is one disease you should consider. But swollen eyes or a runny nose alone do not prove coryza.

Several poultry diseases can look similar. Mycoplasma/CRD, infectious bronchitis, Newcastle disease, avian influenza and other respiratory problems can overlap with coryza. Dust and ammonia can also irritate the eyes and nose. So the right approach is not “I saw a swollen face, therefore it is coryza.” The right approach is to read the whole flock, reduce spread and get a veterinarian involved when the pattern is serious or persistent.

This guide explains what infectious coryza looks like, how it spreads, what farmers should do immediately, how it is diagnosed, when antibiotics may be useful, why treatment may fail, how vaccination fits in and how to reduce repeat outbreaks.

If your birds have several respiratory signs at once, first use our Respiratory Diseases in Chickens guide. If you are still trying to decide whether the birds are generally sick or just showing one odd sign, start with Signs of a Sick Chicken.

Related poultry health guide: For a broader comparison of swollen face, nasal discharge and breathing problems, see our Poultry Diseases and Symptoms in Nigeria guide.

What is infectious coryza?

Infectious coryza is an acute bacterial respiratory disease of chickens caused by Avibacterium paragallinarum. According to the MSD Veterinary Manual, the disease commonly causes reduced activity, nasal discharge, sneezing and facial swelling.

The disease is especially important in laying and multi age flocks because it can reduce feed intake and egg production. It can also become harder to control when other respiratory infections are present at the same time.

What are the common signs of infectious coryza?

Farmers usually notice the face first.

• sneezing;
• watery or sticky nasal discharge;
• watery or foamy eyes;
• swelling around one or both eyes;
• swelling of the face or sinus area;
• eyes partly or completely closed in severe cases;
• rattling or noisy breathing in some birds;
• reduced activity;
• reduced feed and water intake;
• drop in egg production in layers;
• sometimes diarrhoea;
• slower growth or poorer performance when disease is prolonged.

The MSD Veterinary Manual notes that facial swelling can become severe enough to prevent the eyes from opening. But again, that pattern is strongly suggestive:not a laboratory confirmation.

Why do farmers confuse coryza with CRD?

Because both can cause sneezing, noisy breathing, eye problems and nasal discharge.

CRD is commonly associated with Mycoplasma gallisepticum. Coryza is caused by Avibacterium paragallinarum. Mixed infections can also occur, which makes the flock picture even less tidy.

One practical clue is that obvious facial swelling and sinus swelling often push coryza higher on the list. But that is still not enough to diagnose by eye.

What should a farmer check first?

1. How many birds are affected?

One swollen eye may be trauma, irritation or an individual problem. Several birds developing similar swelling and discharge over a short period raises concern for an infectious respiratory disease.

2. How fast is it spreading?

Coryza can spread rapidly within a flock. MSD notes that transmission may occur by direct and indirect contact, droplets and contaminated drinking water.

3. Are there other respiratory signs?

Listen for coughing, sneezing, rales and gasping. Check whether the birds also have green diarrhoea, nervous signs, sudden deaths or a severe egg production drop. Those added signs can shift concern toward Newcastle disease, avian influenza or mixed infection.

4. Is the poultry house irritating the birds?

Strong ammonia, dust and poor ventilation can worsen eye and respiratory signs. Check litter, drinker leaks and airflow. Use the Poultry Litter Management guide and Wet Litter guide if the house is damp or smelling strongly of ammonia.

Quick farmer comparison: coryza or something else?

What you see	What it may suggest	What to do next
Sneezing + facial swelling + nasal discharge	Coryza moves higher on the list	Isolate where practical and call a veterinarian
Sneezing + foamy eyes + rales without obvious facial swelling	Mycoplasma/CRD may be possible	Veterinary assessment/testing
Coughing + nervous signs + green diarrhoea	Newcastle disease becomes a serious differential	Urgent veterinary assessment
Respiratory signs + sudden deaths + head swelling	Avian influenza must be considered	Urgent veterinary/animal health response
Watery eyes + strong ammonia smell	Air quality may be contributing	Fix ventilation/wet litter immediately

How does infectious coryza spread?

Carrier birds are one of the biggest problems. Chickens that recover or remain chronically infected can continue to act as a source of infection for susceptible birds.

Spread can occur through:

• direct contact with infected birds;
• respiratory droplets;
• contaminated drinking water;
• crates, feeders and drinkers;
• workers’ hands, boots and clothing;
• new birds introduced into the flock;
• mixing birds of different ages continuously.

This is why bringing apparently healthy replacement birds into an established flock can still create trouble. Use the PAB quarantine guide before mixing new birds with an existing flock.

What should I do immediately if I suspect coryza?

1. Separate obviously affected birds where practical

This does not guarantee that spread has stopped, because birds may already have been exposed. But it can reduce direct contact and make observation easier.

2. Tighten biosecurity

Use dedicated footwear and tools for the affected house. Restrict visitors. Avoid moving crates, drinkers and equipment between affected and healthy pens.

Our Poultry Biosecurity in Nigeria guide gives the full farm level procedure.

3. Improve air quality

Correct wet litter, dust and strong ammonia. Even if coryza is present, poor air quality can make respiratory signs worse.

4. Record the outbreak

Note bird age, flock size, number affected, first day signs appeared, vaccination history, egg production changes, deaths, recent bird purchases and any treatment already given.

5. Call a veterinarian

This is especially important if facial swelling is spreading quickly, birds are struggling to breathe, egg production drops sharply, treatment has failed, or other serious signs are present.

How is infectious coryza diagnosed?

Typical facial swelling and nasal discharge can make coryza look very likely, but laboratory confirmation is still important when decisions affect a commercial flock.

The MSD Veterinary Manual identifies bacterial culture or PCR as the main confirmation methods.

This matters because several diseases can produce a similar face and respiratory picture. A Namibian investigation also found that other bacteria could be present in birds showing coryza like signs, reinforcing the need to confirm the cause rather than treating the face alone.

Can infectious coryza be treated?

Coryza is bacterial, so appropriate antimicrobial treatment can sometimes help affected birds recover. But that does not mean farmers should guess an antibiotic from the internet.

MSD notes that antimicrobial resistance has been documented in Avibacterium paragallinarum.

The practical message is simple: treatment should be guided by a veterinarian, and where possible by diagnosis and local sensitivity information. Food producing birds also have withdrawal period considerations.

Why does coryza sometimes come back after treatment?

This is a common farmer complaint: “I treated them, they improved, then the problem returned.”

Possible reasons include:

• carrier birds remained in the flock;
• the diagnosis was wrong;
• another respiratory infection is present at the same time;
• the bacteria are resistant to the drug used;
• new susceptible birds were introduced;
• biosecurity between age groups is poor;
• environmental stress is making signs worse.

MSD specifically notes that recurrence can occur after medication is stopped in more severe outbreaks.

Can vaccination prevent infectious coryza?

Vaccination can be useful, especially on farms with a known history of coryza or where the disease is established. But the vaccine must match the disease risk.

Avibacterium paragallinarum has different serovars. Protection against one does not automatically mean strong protection against another. A recent review of infectious coryza, including African experience, shows that vaccine performance can change when circulating serovars change; South African experience is a clear example.

Vaccination question	Farmer answer
Should every flock receive a coryza vaccine?	Not automatically. Risk, farm history, bird type and local veterinary advice matter.
Is one coryza vaccine the same everywhere?	No. Serovar coverage matters.
Can vaccination replace biosecurity?	No. Carrier birds and farm movement still matter.
Should I copy a schedule from another farm?	No. Use a veterinarian/hatchery/local programme appropriate for your flock.
Can vaccinated birds still show coryza like disease?	Yes. Wrong serovar coverage, handling problems, mixed infections or a different disease can explain it.

PAB vaccination rule: this article is not a universal vaccination schedule. Work with a veterinarian, hatchery or competent poultry health professional to design a programme that fits your flock and local disease pressure.

Why coryza can be expensive even when mortality is low

A disease does not have to kill many birds to cost a farmer money.

Coryza can reduce feed intake, slow growth, increase culling, require treatment and reduce egg production. In layers, production losses can be economically important. Published reviews of infectious coryza describe substantial egg production drops during outbreaks, which is why the disease can be costly even when mortality is low.

For a layer farmer, that means the real cost is not only dead birds. It can be the number of trays lost over several weeks.

If production is falling, also use our Layers Are Eating Well but Egg Production Is Dropping guide to check non disease causes at the same time.

Common farmer mistakes with coryza

1. Diagnosing from facial swelling alone. Other diseases and irritation can look similar.
2. Changing antibiotics repeatedly. Treatment failure may mean resistance, mixed infection or wrong diagnosis.
3. Returning recovered birds to a clean flock without thinking about carrier risk.
4. Ignoring ventilation and ammonia. Poor air quality can make respiratory signs worse.
5. Bringing replacement birds straight into the flock. Quarantine matters.
6. Assuming vaccination removes the need for biosecurity.
7. Copying another farmer’s vaccination schedule blindly.

How to reduce repeat coryza outbreaks

• buy birds from reliable sources;
• quarantine new birds;
• avoid mixing age groups unnecessarily;
• use all in/all out management where practical;
• clean and disinfect between batches;
• control movement of crates, tools and workers;
• keep drinker systems clean;
• reduce wet litter, ammonia and dust;
• keep good health and vaccination records;
• discuss vaccination with a veterinarian where farm history justifies it.

The strongest prevention system is not one product. It is vaccination where justified plus good disease prevention, quarantine, biosecurity and good house management working together.

Frequently asked questions

Does a swollen face always mean coryza?

No. Coryza is an important cause of facial swelling, but Mycoplasma, other respiratory infections, sinus problems, trauma and irritation can also affect the face or eyes.

Can coryza cause a drop in egg production?

Yes. Affected laying hens may show a marked production drop, especially during more severe outbreaks.

Can coryza spread through drinking water?

Yes. Contaminated drinking water is one recognised route of transmission.

Can birds that recover still spread coryza?

Yes. Carrier birds are an important reason the disease can persist on multi age farms.

Should I give antibiotics immediately?

Do not guess. Coryza is bacterial and antimicrobials may be useful, but resistance exists and other diseases can look similar. A veterinarian should guide treatment.

Is coryza the same as CRD?

No. Coryza is caused by Avibacterium paragallinarum. CRD is commonly associated with Mycoplasma gallisepticum. They can look similar and may occur together.

The farmer’s bottom line

If several birds develop sneezing, nasal discharge and swollen faces, coryza deserves serious attention. But do not treat the face as a laboratory result.

Check how fast the problem is spreading. Check ventilation and ammonia. Look for other signs. Tighten biosecurity. Separate affected birds where practical. Record the outbreak. Then involve a veterinarian so the diagnosis and treatment plan are based on evidence rather than guesswork.

Veterinary disclaimer: This guide is for farmer education and flock observation. It is not a substitute for examination, laboratory diagnosis or treatment by a qualified veterinarian. Respiratory diseases in chickens often overlap in appearance. If facial swelling, respiratory distress, egg production loss, rapid flock spread or mortality is significant, contact a veterinarian promptly. Do not use antibiotics or prescription medicines without appropriate professional guidance, and follow withdrawal period and local regulatory requirements for food producing birds.