Vet on Call: A fight with mighty chicken mites is easily won by use of pyrethroids

Friday April 21 2017
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Poultry farmer Dan Sobe attends to his chicks in Kehancha. He uses light bulbs to keep them warm. Mites are also an enemy of poultry keepers and can be effectively controlled using pyrethroid solutions. PHOTO | VIVERE NANDIEMO | NATION MEDIA GROUP


My parasitology and bacteriology professors used to insist that we should always treat germs and vermin with respect because when they attack us, they have no malice.

Their sole objective is to thrive, multiply and propagate their species. However, because they also threaten our ability to flourish and propagate our own human species, we must get rid of them using good hygiene, medicines and other chemicals such as insecticides.

My experience is that while farmers will report diseases caused in their animals by germs such as bacteria and viruses with a lot of calm, they sound very aggressive when reporting vermin invasion.

Could it be that is because they are seeing the small noxious creatures such as fleas, ticks and mites but they cannot see germs? I don’t know but that is work for medical sociologists to investigate.

A case of vermin invasion reported to me two weeks ago gave the impression of a person very agitated by the occurrence.

Hello doctor, I am Mariam. Chicken at our school have tiny creatures that are causing havoc to everybody. They are really irritating and annoying especially to the children,” the caller said on phone.


She also informed me she was the environment and hygiene master of the school located in Pangani, Nairobi.

What types of creatures are eating your chicken,” I enquired. Mariam explained there were some small brown, red, black, white and grey creepy things.

Some jumped off the chicken onto people while others just crawled onto clothes and skin.

The crawlers were tiny and almost invisible but their movement and bites were irritating, especially if they hid in the hair, crotch or armpit areas.

Mariam further told me the chicken were losing weight, had dropped egg production and they had some white floury material coming off their skin.

“We can’t stand these creatures anymore and some parents are even threatening to pull out their children from the school,” Mariam concluded.

On arrival at Mariam’s school at 4pm, I noticed the school had about 11 backyard chickens and most of them were patched on the children’s playing equipment, set in what used to be a small car park.


The cars now parked outside the gate.

All the chickens were busy grooming themselves very deeply into the feathers. The chicken close to me had a lot of brown creatures embedded in its head on the comb, wattles and the skin around the face.

Soon, I noticed hundreds of pale white creatures on my black shoes and others crawling up my black trouser like an army of determined invaders.

As I bent to brash off the vermin, Mariam said, “You haven’t seen all of them. Wait until you touch the first chicken.”

I told Miriam the situation was manageable but I had not seen such an intense invasion of chicken mites and fleas on such a small stock of chicken.

There had to be a reason why. I would first begin by treating all the chickens, one at a time, and then explain to her how she would reclaim her environment from the noxious creepy crawlers.

I quickly donned on gloves and a protective laboratory coat and ensured the poultry attendant had also worn protective gear.

Thereafter, I mixed a synthetic pyrethrum chemical known as pyrethroid with water in a large basin at the recommended quantities.

The poultry attendant caught the chickens one at a time and I bathed them in the pesticide. Pyrethroids are good because they kill both the fleas and the mites on chicken.

They also kill chicken lice and ticks and, therefore, one only needs one wash to kill all the different types of vermin likely to attack chicken.

By the time I finished washing the chicken, I could feel some of the mites had found their way into my clothes and were crawling on my skin.

Unfortunately for me, dealing with such mites would have to wait until I got back to the office.

Having completed the chicken dipping, I explained to Mariam and her poultry attendant about chicken mites and fleas.

I further told them they would have to dip the chickens in the pyrethroid solution once per week for another two months until all the fleas and mites were vanquished on the birds and in the compound.

I also explained that their environment, with many pigeons and wild birds, was likely to have bird fleas and mites that drop off the wild birds and attack their chicken.


They would need to regularly inspect their chickens for the vermin and treat them as I had shown them to clear the compound of the invaders.

The school would also stop feeding the birds and pigeons to discourage them from visiting or residing in the compound.

The mite I encountered is scientifically called Dermanyssus gallinae and is the most common in chickens and wild birds in Kenya and many tropical countries.

When birds’ nests are abandoned or when domestic birds mix with wild ones, the mites migrate to the former. They unleash multiple blood sucking bites on the chicken, causing a lot of discomfort, loss of weight, loss of blood and poor egg production.

The mites also bite humans causing skin redness and irritation. They have been known to transmit the viral infection, St. Louis encephalitis, in humans in the US.

Chicken mites are about one millimetre long, pale white and almost invisible when unfed, bright red when recently fed and grey to black when the blood they have sucked is partially digested.

These variations explain why Mariam was seeing creatures of different colours.

Chicken mites are most vicious when they are white since they are starving. The mites bury themselves deep in a chicken’s feathers to access the skin to feed and also get protection.

As they feed, the chicken skin develops scales which fall off as floury material when the birds try to remove the mites by deep beak grooming.

Chicken fleas attach themselves around the head and anal region of the chickens causing irritation, blood loss and death especially of chicks.

The fleas also bite humans and other mammals.

A week-and-a-half after starting the flea and mite control at Mariam’s school, she called to confirm that the vermin load was quickly going down and so were the children’s complaints.