Bird Flu in the Philippines: The Record Has a Season

Every page I can find about avian influenza in this country answers the same two questions. Where has it been, and is it here right now. One of them, the disease pillar on this site, answers at length: Central Luzon carries the bulk of the record, and bakuran flocks are what the current wave has been landing on.

The question none of them answer is when in the year. That is the one a keeper is actually holding. Kung maglalagay ka ng 50 manok, may petsa ang simula at may petsa ang bentahan. Hindi mo maililipat ang barangay mo. You can move the month you start, at malaki ang puhunan na nakasakay sa desisyong iyon.

So I counted the dates myself. Across the 251 Philippine outbreak dates in the WOAH WAHIS notification record from 24 July 2017 to 24 June 2026, read here on 13 August 2026, February, March and April carry 99 of them. That is 39.4% of nine years of record sitting inside a quarter of the calendar. Every date in that count comes from a report anyone can open, like the one behind the most recent row, 24 June 2026.

One rule governs every sentence below. Each figure here is a date on which an outbreak was reported, tested, confirmed and notified to WOAH. It is not a date on which birds got sick. Ang kawan na hindi naireport ay wala sa anumang bilang, so what you are reading is a count of what got noticed, and it runs short by an amount nobody can state.

The monthly breakdown is my own tally of the WAHIS reports rather than a monthly series WOAH publishes. Every row it is built from now has somewhere to be read: the date, the WAHIS report it came off and the day it was read are on the outbreak record, one row at a time. One of the 251 dates is a wild-bird detection and not a poultry flock, which makes it 250 poultry dates plus that one. The tables below keep it in.

Which months carry the record?

March is the peak and the gap is wide: 43 dates, 17.1% of everything from 2017 to 2026. Malayo ang agwat sa pangalawa. It is also the most repeated month in the record. Of the seven years carrying any Philippine notification at all, six carry a March date. The exception is 2017, which only enters the record in July and never had a March to carry.

September and December sit at the other end, 6 dates each, 12 of the 251 between them, 4.8%. A kawan on the ground through those two months is on the ground through the thinnest stretch in nine years of record.

Does the pattern survive without 2022?

2022 is an outlier large enough to break any reading built on it. That one year carries 132 of the 251 dates, more than the other six years in the record put together, and a seasonal shape that exists only because of one bad year is not a shape. The honest check is to remove it and look again.

The 119 dates left give February, March and April 50.4%. Half the record inside a quarter of the year, which is a stronger pattern than the full count showed, not a weaker one.

The 2022 column repays a second look for a different reason. In the full record May, June and July look busy, at 23, 29 and 29 dates. Strip 2022 out and those same three months fall to 7, 9 and 6. The mid-year weight in the nine-year total belongs mostly to that one year.

Five of the seven years sit at 30% or above, which against a flat calendar’s 25% looks decisive. For two of the seven, 25% is the wrong baseline to begin with. 2017 enters the record only in July, and 2026 stops on 24 June. February to April is three of the roughly six months 2026 covers, so a flat calendar hands that year about 50% on its own, and its 59% is barely above chance. Read it as one year, not as the argument.

Take out both partial years, take out 2022, and four complete years are left: 2020, 2023, 2024 and 2025. They hold 88 dates between them and February to April carries 44 of those, which is 50.0%. Half the record, a quarter of the calendar, with the one year capable of manufacturing the whole thing deleted. Manipis pa rin ang pundasyon: four complete years, and the only thing that firms this up or dissolves it is another three or four years of notifications.

One objection is worth taking seriously, kasi hindi pantay-pantay ang pinagmulan ng mga petsa. The pillar puts Central Luzon at 57.8% of the record, and that figure counts the 145 dates where it is the only region on the row. It is named alongside another region on 23 more, so it is in 168 of the 251 either way, 66.9%. A keeper in Cagayan Valley or Iloilo can fairly ask whether this is the country’s season or Bulacan’s. The wider count is the one the test has to remove: drop only the 145 and 23 Central Luzon dates stay inside the remainder, which answers nothing. Drop every date whose region field names Region III at all and 83 are left. February to April carries 39 of them, 47.0%, higher than the national 39.4%. Whatever this cluster is, hindi ito gawa ng iisang rehiyon na pumuno sa archive.

Here is the whole year as one ring, with February, March and April marked and both shares printed inside it: 39.4% across all 251 dates, and 50.4% with 2022 taken out. Nothing in it is drawn taller than anything else, kasi hindi ito bar chart, and the counts stay in the month table above. What a ring carries that a table cannot is which months come before the marked stretch. Those are November, December and January, at doon pa lang may magagawa ka.

Season ba talaga, o reporting lang?

A cluster of reported outbreak dates in February, March and April may be a disease season. Pwede rin namang reporting season lang. Surveillance effort rises and falls, culling campaigns run in waves, notification to WOAH lags confirmation by an amount that is not constant, at ang probinsyang aktibo sa pagreport ay gumagawa ng sunod-sunod na petsa. A quiet probinsya never generates them. Nothing in the WAHIS record separates any of that from the underlying infection pattern, and I have no read source that does.

I cannot tell you which of the two it is. Nobody can, from this dataset.

What would settle it is a denominator. Tests run per month, o kaya bilang ng barangay na nabisita kada buwan, published by DA or BAI: put either one underneath these counts and the reporting question stops being unanswerable. The numerator is public and the denominator is not. That gap sits in the same family as the ones tracked in the gaps register.

No Philippine institution I can find publishes a seasonality analysis of the national outbreak record. What you have just read is my own count of a public dataset, dated 13 August 2026, and it is not the position of DA, BAI or WOAH. If you find something better from DA or BAI, follow that instead of this.

A count by month is only as good as the date on each row, and three rows in this archive have already been struck for carrying a wrong one. The clearest of the three was filed on 10 July 2026 and turned out to hold the day the notification reached WAHIS rather than the day the outbreak started, which WAHIS puts at 2 May 2026. That row had been sitting in July’s column and belonged in May’s. Hindi binura ang tatlo. Nandiyan pa rin sila, may guhit sa gitna, kasi in-place ang pagwawasto sa file na ito.

Withdrawn rows only, 3 of the 254 rows this archive holds. Nothing is deleted: the full reason on each withdrawal, and the WAHIS report behind every live row, are on the outbreak record page. The 251 dates counted on this page are the live rows.

I am also not going to tell you why the record falls where it does. Weather, migration, wild-bird movement, lahat iyan ay pwedeng hulaan at wala sa archive. Naming the pattern is what the count supports.

Where is it right now?

Seasonality is a planning tool, not a status check, kaya tingnan mo muna ang may petsang bilang bago ka kumilos. At 7 August 2026 BAI recorded 168 barangays still under an avian influenza restriction against 6 with an on-going case, and the two columns are not interchangeable for reasons the pillar argues in full. Both group pages carry the run of weekly counts behind that row, not only the 7 August 2026 reading.

Everything above this section is a nine-year count and ages by years. The restriction figure ages by weeks, so it carries its own date and the BAI report it came off, and you can see how stale it has gone by the time you are reading this.

If that week is months behind you, the count is history and the two group pages above have the newer rows.

So kailan ka maglalagay ng batch?

I will take a position here, kasi ang alternatibo ay ang payo na nasa lahat ng dako: risk is always present and biosecurity always matters. Totoo, at walang silbi sa isang desisyong may petsa.

A broiler batch is on the ground for 35 to 45 days, so a placement carries its birds across roughly two calendar months rather than landing them on a single sale date. Sisiw placed in the first week of January are at market weight by the middle of February, not March. That is the arithmetic to plan on, and the whole calendar of it falls out of the monthly counts above.

Moving out of the heavy end is not free, and the cost is not only a rescheduled batch. The months that table steers you toward are the weak ones at the farmgate. Across the 198 valued monthly rows in the PSA household broiler farmgate series, September and October average about ₱111.33 per kilo liveweight against roughly ₱114.10 for February to April, a difference of ₱2.77 a kilo. Ang binabawas mo sa panganib ay binabawas mo rin sa presyo. On a 50-bird batch that is a couple of hundred pesos of gastos you never see coming back.

What none of this gives you is a safe window. Every month in that table carries dates, pati ang mga tahimik. September has 6, and if one of those 6 had been your kawan the annual share would have meant nothing to you. The pattern describes a population of reported outbreaks over nine years. Hindi nito inilalarawan ang bakuran mo sa kahit anong buwan, at hindi nito kaya.

The asymmetry is the rest of the position. If the February to April cluster turns out to be a reporting artefact, a keeper who moved a batch away from it gave up ₱2.77 a kilo and a rescheduled calendar for nothing. If it is real and you ignored it, the batch is what you lose. Magkaiba ang laki ng dalawang iyon, at doon nakasandal ang buong desisyon.

Who the outbreaks landed on is a separate question with a firmer answer, and the pillar has it: backyard-classified flocks carried 23 of the 27 dates recorded in 2026. Basahin mong mabuti ang label na iyon. The country picks that category itself when it files, and operations running birds by the thousand sit comfortably inside it.

Cite this page

Every figure here carries the source it came from and the date it was read. If you use one, this is the line that says where it came from.

A backyard poultry keeper. "Bird Flu in the Philippines: The Record Has a Season". Manoknomics. Published August 22, 2026. https://manoknomics.com/articles/bird-flu-philippines-when-outbreaks-happen

Select the text to copy it.

Questions people actually ask

When is bird flu season in the Philippines?

No Philippine agency declares one. In the 251 outbreak dates the Philippines notified to WOAH between 24 July 2017 and 24 June 2026, March is the single peak month at 43 dates, and six of the seven years carrying any notification at all carry a March date. Take out 2022, the one year holding 132 of the 251, and take out the two partial years, and February to April still carries 44 of the 88 dates left. Read it as a pattern in reporting as much as in infection: nothing in the record separates the two.

How many bird flu outbreaks has the Philippines recorded in 2026? Show the answer

The WOAH WAHIS record holds one row per date rather than one per flock, so the honest count is dates: 27 outbreak dates to 24 June 2026, already past the 16 recorded across the whole of 2025 with half the year still to run. 16 of the 27 fall in February, March or April. These are confirmed and notified dates, so the count is a floor rather than a total.

Should I move my broiler batch away from bird flu season? Show the answer

It is a real option and it is not free. The thinnest months in the outbreak record are September and December, 6 dates each out of the 251 the Philippines notified to WOAH over nine years, against 43 in March. The price cost runs on a slightly different pair of months: PSA household broiler farmgate averages about ₱2.77 per kilo less across September and October than across February to April, so a placement timed to miss the cluster also tends to harvest into the softer half of the price year. Weigh a couple of hundred pesos on a 50-bird batch against the chance of losing the batch entirely, and note that the seasonality itself may be a reporting pattern rather than a disease one.

Does the Philippines get bird flu every year? Show the answer

No. Three years in the WOAH record for the Philippines carry no notified outbreak dates at all: 2018, 2019 and 2021. One year carries 132 of the 251 dates in the whole nine-year record, which is 2022. Avian influenza in this country is episodic in the record rather than steady.