Infectious Coryza in Ghana: Swollen Heads and a Foul Smell

You will usually smell infectious coryza before you see it. A farmer from Dodowa described it to us on the phone as "the house smells like something died, but nothing has died". When she walked the rows she found a dozen hens with one eye swollen shut, a wet crust below the nostrils and a sticky discharge that gave off that unmistakable rotten odour. Egg collection had fallen from 14 crates a day to 10 in about a week. Her flock was 34 weeks old and at the peak of lay; the timing could not have been worse.

Infectious coryza is one of the most common respiratory diseases on Ghanaian layer farms and one of the most under-recognised, because it rarely kills many birds outright. Farmers see swollen heads and reach for whatever antibiotic is in the cupboard, the swelling subsides, and the disease settles into the flock as a chronic drag on production that comes back with every stress. In multi-age layer operations, which describes most commercial egg farms around Kasoa, Dormaa, Kumasi and Sunyani, it can become permanent.

This guide explains what causes coryza, how to tell it from the diseases it is confused with, what the disease does to an egg flock financially, how treatment and vaccination fit together, and what we tell farmers who buy pullets from us about keeping it out. Everything on medication here is for orientation; your veterinarian must confirm the diagnosis, the drug, the dose and the withdrawal period before you treat.

What causes it and how it behaves

Infectious coryza is caused by a bacterium, Avibacterium paragallinarum (formerly Haemophilus paragallinarum). It infects the upper respiratory tract: the nasal passages, the sinuses under the eyes, and sometimes the trachea and air sacs. The bacterium has three main serovars, A, B and C, and immunity to one does not protect well against the others, which matters when you choose a vaccine. It is a fragile organism outside the bird, surviving only a few hours in the environment, and it does not pass through the egg. In practice this means coryza almost always arrives on a farm inside a live carrier bird, and almost never in a box of day-old chicks from a clean hatchery.

The incubation period is very short, one to three days, and the disease spreads through a house within a week by direct contact, by droplets from sneezing birds and through shared drinking water contaminated with nasal discharge. Morbidity is high: 50 to 100 percent of a susceptible flock will show signs. Mortality is usually low, often under 5 percent, unless a second infection such as Mycoplasma gallisepticum, infectious bronchitis or E. coli takes advantage of the damaged airways. That combination, coryza on top of chronic respiratory disease, is where Ghanaian flocks lose birds and it is common on farms that have never controlled either.

Birds that recover remain carriers. This is the central fact about coryza and the reason it is so hard to shift from a multi-age farm. A hen that had coryza at 30 weeks and now looks perfectly normal will shed the bacterium under stress and infect every new batch of pullets brought into the same house or the house next door. Farmers who keep three or four ages on one site with shared workers, shared equipment and a shared water source are effectively running a coryza maintenance system.

The signs: what you will see, smell and count

The classic picture in a layer is unmistakable once you have seen it: a swollen face, especially the area between the eye and the beak (the infraorbital sinus), on one or both sides. The eye may be partly or completely closed by the swelling. There is a watery nasal discharge that becomes thick and sticky, crusting around the nostrils, and a foul odour that is distinctive to coryza and comes from the anaerobic bacteria that follow it into the sinus. Wattles may swell, particularly in cockerels. Birds sneeze and shake their heads; the sound of a house of sneezing hens at night is one of the first things an experienced worker notices.

• Swollen face and sinuses, one or both sides, soft and warm at first, sometimes firming into a cheesy lump if untreated.
• Nasal discharge, watery to sticky, with a bad smell; crusty nostrils; feed stuck to the face.
• Conjunctivitis, watery eyes, eyelids stuck together, eye closed by swelling.
• Sneezing, head shaking, occasional rattling breathing if the trachea is involved.
• Drop in feed and water intake, birds standing quietly with ruffled feathers.
• Egg drop of 10–40 percent, appearing within a week of the first swollen faces and lasting three to six weeks.

What else looks like coryza

Several diseases produce a swollen head, and treating the wrong one is expensive. The table below lists the ones that farmers in Ghana most often confuse.

A field guide only. Laboratory culture or PCR from a sinus swab confirms coryza, and a veterinarian can distinguish these on post-mortem. Sudden heavy deaths with swollen heads must be reported to the Veterinary Services Directorate the same day.

The single most useful test a farmer can do is to open the sinus of a freshly dead or culled affected bird. In coryza, a thick, foul-smelling, sometimes cheesy material fills the sinus and the lining is red and swollen. In CRD the sinus may be clear but the air sacs, when you open the body, are cloudy or contain yellow material. Many Ghanaian flocks have both, and the smell tells you which is dominant. Our CRD guide covers the mycoplasma side, and the common diseases overview shows the full list.

What coryza costs an egg farm

Because mortality is low, farmers often treat coryza as a nuisance. The numbers say otherwise. Take a 2,000-hen Lohmann Brown flock at 32 weeks laying at 92 percent, or about 1,840 eggs a day, roughly 61 crates. A moderate coryza outbreak that drops production by 25 percent for four weeks costs about 460 eggs a day, or 15 crates. Over 28 days that is 420 crates. At a farm-gate price of around GH₵ 55–75 per crate in 2026, the lost revenue is somewhere between GH₵ 23,000 and 31,500, before any treatment cost and before the fact that a flock hit at peak rarely returns fully to its previous curve. Add the antibiotic bill, the egg withdrawal period and the labour, and a "mild" disease has cost more than the pullets did.

Treatment: what works and what only looks like it works

Coryza is bacterial, so antibiotics do reduce signs quickly, usually within two or three days. The problem is that no antibiotic clears carriers, so the flock will relapse when treatment stops or when the next stress arrives. Treatment buys time and limits the egg loss; it does not solve the problem. The solution is vaccination and separation of ages, covered below.

Drugs that veterinarians in Ghana commonly use for coryza include sulphonamide combinations (such as sulfadimidine or trimethoprim-sulfa), tetracyclines (oxytetracycline, doxycycline), erythromycin and tylosin, and in some cases fluoroquinolones or amoxicillin. Which one is appropriate depends on what is licensed for laying hens, on the local resistance pattern and on the withdrawal period for eggs. Several of these drugs are not approved for hens producing eggs for human consumption in many countries, and sulphonamides in particular have a long egg withdrawal. Do not guess. Have a veterinarian examine birds, ideally send a sinus swab for culture and sensitivity, and follow the label dose, duration and withdrawal exactly. Under-dosing by "putting a bit in the water" is the fastest way to breed resistant bacteria on your own farm.

Supportive care matters at least as much as the drug. Birds with swollen faces and blocked nostrils eat and drink less, so:

• Add a vitamin and electrolyte supplement to the water for the duration of treatment and a week after; vitamin A supports the lining of the respiratory tract.
• Make sure every bird can reach water easily; lower drinker height slightly for birds with swollen eyes.
• Improve ventilation without creating draughts. Ammonia from wet litter irritates already-inflamed airways and prolongs the outbreak. See our ventilation guide.
• Reduce every other stressor: no handling, no moving, no vaccinating, no feed changes during the outbreak.
• Cull birds with hard, cheesy sinus lumps that do not respond; they are permanent shedders and will not lay well.

Vaccination: the only real control on a multi-age farm

An inactivated (killed) coryza vaccine is available in Ghana through veterinary suppliers, usually as an oil-adjuvanted bacterin containing serovars A and C, and in some products A, B and C. It is given by injection, subcutaneously in the back of the neck or intramuscularly in the breast or thigh, and it requires two doses about four weeks apart in pullets, with the second dose at least three to four weeks before the expected onset of lay. A common programme is a first dose at 8–10 weeks and a second at 14–16 weeks, though your veterinarian will place it around your other injectable vaccines (fowl typhoid, Newcastle killed, EDS) within the full programme in our vaccination schedule.

Three points about the coryza vaccine that farmers often get wrong. First, it must be given before exposure. Vaccinating a flock that already has coryza does little; the bacterin needs three weeks to produce protection and the disease incubates in three days. Second, serovar matters. If the strain circulating on your farm is serovar B and your vaccine contains only A and C, protection will be poor. A laboratory isolation from your own farm, arranged through your vet, tells you which vaccine to buy. Third, the vaccine reduces the severity of disease and the production drop; it does not always prevent infection completely, so it must be combined with the management steps below rather than replacing them.

Prevention: breaking the carrier cycle

Since the bacterium survives only hours outside a bird and does not pass through the egg, coryza is entirely a problem of live-bird contact. Every prevention measure follows from that.

1. All-in, all-out by site if you can, by house if you cannot. The most reliable way to clear coryza from a farm is to depopulate completely, clean and disinfect, rest the houses for at least two to three weeks, and restock with clean pullets. On a small farm with two houses this is achievable once a cycle. On a large multi-age site it is a long-term plan, but it is the plan.
2. Never mix ages in one house and keep a minimum distance and separate equipment between houses of different ages. If a worker must move from an older to a younger flock, it is boots, overalls and hands first.
3. Source pullets from a single, known supplier with no coryza history, and never buy "point of lay" birds from a market or from a farm that is selling off part of an older flock. Bought-in adult birds are the classic route of introduction.
4. Quarantine anything that arrives alive, including a cockerel from the village or a gift of hens, for at least three weeks well away from the flock. Ideally, nothing arrives alive except day-old chicks.
5. Clean water lines and drinkers. Nasal discharge in a shared bell drinker infects the whole row. Daily cleaning of drinkers and periodic flushing of nipple lines reduce the dose.
6. Control ammonia and dust. A healthy respiratory lining resists infection; one burnt by ammonia does not. Dry litter and ventilation are prevention, not just comfort.

Our full biosecurity guide goes deeper on the farm entrance, visitors and vehicles. For coryza specifically, the live-bird rule is the one that matters most.

A mini-case: the pullets that "brought" coryza

A farmer at Nsawam with 3,000 layers in three houses of different ages bought 1,000 pullets from us in 2025 and put them into a house that had been emptied of a 90-week flock only four days earlier. That old flock had been treated for "swollen heads" twice. Within ten days the new pullets, then 17 weeks old, were sneezing and swelling, and he called to say our pullets had arrived with coryza. We understood the frustration, but the timing did not fit: coryza incubates in one to three days, and the pullets had been on his farm ten days when it appeared, after leaving a rearing site with no coryza history and no sneezing in the batches that went elsewhere the same week.

His vet swabbed the sinuses of birds in all three houses and cultured A. paragallinarum from every one, including hens in the oldest house that had "recovered" months earlier. The new pullets had walked into an infected site. He treated under veterinary direction, started coryza vaccination for all future pullets at 9 and 13 weeks, and moved to resting each house for three weeks between flocks. His next batch, placed into a house that had stood empty and disinfected for 24 days, came into lay without incident and peaked at 93 percent. The cost of the empty house for three weeks was far less than the eggs he had been losing on every flock for years.

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