A Primary School of 780 Pupils Had 23 Dengue Cases in One Term, Until Parents Stopped Sending Their Children
Last updated: 7 Sep 2026 | 1 Views |
A true story from a primary school in Khon Kaen, Thailand
A Primary School of 780 Pupils Had 23 Dengue Cases in One Term, Until Parents Stopped Sending Their Children
When the playground and the garden built for the children become the most dangerous places on campus
A primary school of 780 pupils in Khon Kaen recorded 23 confirmed dengue cases in a single term, until some parents refused to send their children at all. Here is what the school found when it finally surveyed properly, and how the AIROFOG AT35 thermal fogger changed the numbers within one term.
The 52-year-old director of a primary school of 780 pupils in Khon Kaen province says the first term of last year was the hardest of his career in school management.
It began with one Grade 3 pupil absent with a high fever. The following week three more from the same and adjacent classrooms. By the end of term, 23 pupils had confirmed dengue, nine of them requiring hospital admission.
What worried the director most was not the case count. It was that parents stopped sending their children. In the worst week, 118 pupils were absent on a single day — most of them not ill at all, but kept home because their parents were afraid.
What the teachers found when pupils surveyed the campus
The director tried something different. Instead of having the caretakers survey alone, he had the science teacher take the Grade 5 and Grade 6 pupils around the whole campus to survey mosquito breeding sites as a learning activity, recording and photographing what they found.
The result stunned the staff. The children found 74 points holding water, with live larvae at 41 of them — and the highest concentration was not where the adults expected. It was in the playground and the ornamental garden the school was proudest of.
What the children found included 12 tyres used to build playground equipment, every one holding water; 28 plant saucers around the buildings; the drip tray under the drinking water filter; blocked roof gutters; and an uncovered water jar behind the canteen.
The finding that silenced the teachers was the ornamental lotus pot by the flagpole and a handwashing basin with a leaking tap that kept water standing underneath it permanently — points every child passes several times a day, metres from where they line up each morning.
Why schools warrant particular vigilance
The health officers joining the investigation explained that schools stack several risk factors. First, children are densely gathered in a confined area for many hours a day, five days a week, which produces case clusters quickly.
Second, school hours coincide with Aedes activity. Aedes feeds heavily in the early morning and late afternoon — exactly when children line up at the flagpole and when school ends — plus the lunch break when they play outside.
Third, clothing. Most primary pupils wear shorts and short socks, leaving exposed the legs Aedes prefers most, and children often do not notice being bitten until it itches.
Fourth and most important, dengue in children carries a higher risk of shock syndrome than in adults, and some children deteriorate without clear warning. A school caring for hundreds of children therefore has a direct responsibility to make the environment as safe as it can be.
Consequences that reach well beyond the sick room
Pupils absent through illness lost hundreds of school days between them, and the nine admitted to hospital each missed five to ten days. At primary level, where content builds continuously, several consecutive days out has a clear effect on learning.
But the larger effect came from pupils who were not ill and whose parents kept them home. In the worst week 118 children were absent on one day, which disrupted teaching across the whole school and forced teachers to repeat material several times.
The director says he had to hold two parent meetings that term, and they were the hardest of his career, because parents asked a question he could not answer with confidence: what has the school actually done?
And there is a cost nobody discusses: families of sick pupils had to take time off to care for them. In an area where most parents are daily-wage workers, five days off means real lost income affecting the whole household.
What the school did, and the following term's numbers
The director planned in three parts with the school health teacher, the village health volunteers and officers from the sub-district health promoting hospital. The first was eliminating all 74 sites the children had found.
That took two weeks: drainage holes drilled in every playground tyre, planters changed so saucers were unnecessary, gutters cleaned on every building, leaking taps repaired, a lid fitted to the canteen water jar, and guppies stocked in the lotus pot by the flagpole.
The second was making the breeding site survey a monthly learning activity, with Grade 5 and 6 pupils walking the campus and calculating the larval index each month, then reporting it at morning assembly — an activity the children genuinely enjoy and learn from.
The third was requesting budget to buy a thermal fogger as school equipment. They chose the AIROFOG AT35 and had a trained caretaker fog every Friday after school, so the aerosol dissipates completely before Monday, with an immediate additional application whenever a pupil is reported ill.
What it actually costs
Children's health and safety are not negotiable
Dengue in children carries a higher risk of shock syndrome than in adults, and some deteriorate without clear warning. A school caring for hundreds of children for hours every day has a direct responsibility to make the environment as safe as possible.
Teaching time lost across the whole school
Sick pupils missed five to ten days each, and many more who were not ill stayed home because parents were afraid. In the worst week 118 children were absent on one day, disrupting teaching across the entire school.
Parents' confidence, which affects everything else
When parents lose confidence in a school's safety, cooperation declines across the board — attendance at activities, support for school projects, and in some areas transfers to other schools.
The burden on pupils' families
In an area where most parents are daily-wage workers, a sick child and five days off work means real lost income affecting the whole household — a cost that never appears in any school report but is entirely real.
Why the usual fixes do not work
Asking children to bring their own repellent
This shifts the burden to parents, and in practice most children forget or do not apply it. Those who do sweat it off within an hour of playing. Above all it removes not one mosquito from the campus.
Having caretakers mow and clean more often
Necessary and worth doing, but insufficient, because the principal breeding sites were 74 water-holding points distributed across the campus, which mowing does not address — and many of them sat in areas that already looked clean and tidy.
Fitting insect screens to classrooms
Somewhat helpful in rooms that can be closed, but children are bitten hardest lining up at the flagpole, playing outside at lunch and waiting for parents after school — all outdoors. And most classrooms keep windows open for ventilation anyway.
Waiting for the sub-district administration or municipality to spray
Local authorities have limited resources across a whole sub-district, generally come only after cases are reported, and come once. A school needs continuous weekly management through the rainy season, especially with hundreds of children on site every day.
Using aerosol cans in the classrooms
These cover a tiny area and dissipate quickly, and are inappropriate around small children and those with allergies. Above all the real problem is outdoors — the playground, the garden and the tree lines around the buildings — which aerosols cannot cover.
A school needs to fog on its own schedule, at times when no children are present
Once you know there were 74 breeding sites inside the campus and that children are bitten while outdoors, the requirement is clear: eliminate the breeding sites first, then continuously suppress the adult mosquito population across the outdoor areas.
A thermal fogger is right for this, because the fog drifts into the tree lines around the buildings, the garden shrubbery, beneath raised classroom blocks, around the playground and along the fence adjoining vacant land — harbourage nothing else reaches.
The best window for a school is Friday evening after classes, because the aerosol dissipates entirely before Monday morning and no children are on site for the following two days, which is the safest possible arrangement.
And the machine must belong to the school, because it needs applying weekly through the rainy season plus immediately whenever a pupil is reported ill — a rhythm no external body can supply. Hence the AIROFOG AT35, which conforms to the standard equipment schedule and which caretakers can operate.
10 reasons the AIROFOG AT35 thermal fogger solves it
1. Compliant with Thailand's government standard equipment specifications
For schools under the Basic Education Commission, municipal schools and other public institutions, the AIROFOG AT35's conformity means the budget request and reference price sit correctly within the category, and acceptance inspection requires no reinterpretation.
2. Trained caretakers can operate it themselves
Schools have no specialist staff for this. The AT35 is simple enough to train two caretakers as responsible operators, so fogging becomes a weekly routine like any other building maintenance task, at no additional labour cost.
3. Fog reaches tree lines, shrubbery and the spaces beneath classroom blocks
Mosquitoes on a campus rest in the tree lines around the buildings, the garden shrubbery, beneath raised classroom blocks, around the playground and along the fence adjoining vacant land. The AT35 produces a fog that genuinely drifts into all of them — impossible with aerosol cans.
4. Covers the campus in well under an hour
A primary school of 700 to 900 pupils with playing fields and gardens takes roughly 40 to 60 minutes with the AT35 — short enough to do every Friday after school without disrupting anything else.
5. A 100 percent stainless steel body that lasts for years on a limited budget
Schools receive equipment budget infrequently, so what they buy has to last. A stainless body does not corrode even stored in a humid supply room, giving a far lower cost per year than a cheap machine replaced every two or three years.
6. Runs both water-based and oil-based formulations
Educational institutions must choose chemistry with care because children are involved. Accepting both formulation types lets the school follow local health officers' recommendations and rotate products to slow resistance.
7. An immediate additional application whenever a pupil is reported ill
This is the most valuable capability for a school. On being told a pupil has dengue, the school should fog the same day to reduce onward transmission on site. Ownership makes that possible immediately, without queueing behind any agency.
8. Certified to German and British standards
For a facility caring for children, internationally certified equipment is something the school can show parents and the school board as evidence that it uses equipment genuinely tested for safety and droplet consistency.
9. 100 percent quality control before dispatch
Every unit is run-tested before shipping, which matters for school equipment acceptance inspection and assures the school that the machine works from day one rather than entering a warranty process.
10. A Thai service centre with genuine parts and 10-plus years of technician experience
Schools receive equipment budget rarely and have little repair budget. Domestic service and genuine parts stop the machine becoming unusable equipment for want of a part — the most common problem schools across the country face.
Before the thermal fogger
- 23 pupils with confirmed dengue in one term, 9 hospitalised
- 118 pupils absent on a single day in the worst week
- 74 water-holding points found on campus, with larvae at 41
- Most breeding sites in the playground and ornamental garden
- Two parent meetings needed in a single term
- No equipment of the school's own, waiting on local authorities
After the thermal fogger
- Dengue cases down to 2 the following term
- Absence rates back to normal
- No more than 3 sites with larvae on the monthly survey
- Grade 5 and 6 pupils surveying and reporting the larval index every month
- Fogging every Friday after school by a trained caretaker
- Parents receiving a monthly report and cooperating far better
The three-step process
1. Have the pupils survey the breeding sites as a learning activity
Rather than leaving it to the caretakers, have the science teacher take the older pupils around the campus, recording and photographing every point holding water. This achieves two things at once: far more detailed data, and children who take home knowledge they genuinely use.
2. Eliminate every breeding site before you start fogging
Drill drainage holes in every playground tyre, switch to planters that need no saucers, clean the gutters on every building, repair leaking taps, fit lids to all jars and drums, and stock larvivorous fish where water must remain. Fogging without source reduction means fogging forever.
3. Fog every Friday evening, and again whenever a case is reported
Apply after school on Friday so the aerosol clears entirely before Monday, concentrating on the tree lines, the garden, the playground, beneath the buildings and along the fence. Add an immediate application on the day any pupil is reported ill, and log every application for the school board and parents.
From someone who uses one
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The breeding sites teachers and caretakers most often miss
Tyres used to build playground equipment are the most common and most serious finding, because water inside evaporates extremely slowly and is invisible from outside. Many schools use tyres for seating, tunnels and planting beds — all of which hold water. Drilling a drainage hole in the underside of every tyre is a one-time measure with a permanent effect.
Plant saucers around the buildings are the most numerous. Schools that keep their grounds attractive often have dozens or hundreds of pots, watered daily so the saucers are permanently full. The fix is switching to a system that drains without saucers, or drilling every saucer.
Drip trays under drinking water filters, and handwashing basins with leaking taps, are points children pass several times a day that nobody regards as breeding sites. Make checking them a line item on the weekly building inspection.
The last is roof gutters blocked with leaf litter, found at almost every school with mature trees around the buildings. Clean them before every rainy season and check again mid-season.
Why involving pupils in the survey works better than expected
What this school discovered by accident is that having older pupils survey the breeding sites works markedly better than having adults do it. The first reason is that children are smaller and look at a different eye level, so they see what adults miss — under benches, in the gaps behind pots, and beneath playground equipment.
The second is numbers. Two classes surveying together cover the entire campus in tens of minutes, where two caretakers would need days.
The third and most important is that what the children learn does not stay at school. A child who knows that tyres and plant saucers breed mosquitoes goes home and checks there too, which extends the effect into the community at no additional cost.
Many schools therefore run this as a continuing project, with pupils surveying and calculating the larval index monthly and reporting it at assembly — delivering science, mathematics and civic responsibility in one activity.
Frequently asked questions
Is fogging safe at a school with children?
Yes, when applied at times no children are present. The best approach is Friday evening after school, so the aerosol clears across the two days before Monday, with canteen equipment covered and classroom windows closed during the application.
When should we fog?
Friday evening after school is ideal for a school, because there are two full days before the children return. If a mid-week application is needed because a pupil has been reported ill, apply after school and allow at least overnight before classes resume.
How many machines does a school of my size need?
Up to 500 pupils, one machine is enough. For 600 to 1,200 pupils with several buildings and large grounds, two, so a full pass finishes within an hour. Large secondary schools covering many rai should consider three.
How often should we fog?
Weekly through the rainy season and fortnightly in the dry, plus an immediate application whenever a pupil is reported with dengue — alongside the monthly breeding site survey, which is the indicator you use to adjust frequency.
Can caretakers operate the machine?
Yes. Designate two responsible operators and train them fully on mixing ratios, personal protective equipment, application technique and cleaning the machine after every use. In many areas local health officers or the sub-district administration will run the training.
Which budget can we use to buy it?
The equipment category, referencing the standard equipment schedule, which already lists thermal foggers. Many schools also fund the purchase through sub-district or municipal support grants, or donations from the school board and alumni.
How should we communicate with parents?
A one-page monthly report works best: which days fogging happened, how many risk points were found, how many were fixed, and how many pupils were ill compared with last month — sent through the parent messaging group and posted at the school gate. It restores confidence fastest.
What if the machine fails?
AIROFOG maintains a service centre and genuine parts in Thailand with technicians of more than 10 years' experience, so there is no risk of the equipment becoming unusable for want of a part — the most common problem schools face with equipment bought from non-authorised sellers.
The problem had been inside our own fence all along
The clearest lesson here is that we assume the problem comes from outside, when a proper survey found all 74 breeding sites inside the school's own fence — and many of them in areas built specifically for the children.
Having the pupils do the survey is not merely a way to save effort. It turns the issue from a caretaker's chore into knowledge children take home, extending the effect into the community at no extra cost.
And for a school, owning the equipment, keeping to a real schedule, and producing a report parents can see is what turns the question at the parents' meeting from one you cannot answer into something the school is proud to tell.
Talk to the World Health Disinfection team about a mosquito control plan for your school — machine selection, equipment budget guidance, chemistry and staff training.
See the machine and pricing — click here
Call 065-556-6294 or add LINE @whd268
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