The academic year has only just begun and scabies infections among students are already on the rise. Physician microbiologist Matthew McCall of Radboudumc in Nijmegen thinks it is time for a coordinated approach to scabies. “The GGD should play a coordinating role in this, as with other infectious disease outbreaks. They can provide better information and set up source-and-contact research. They already do this during outbreaks in healthcare institutions, but this is just as important in student populations. The GGD already has a scabies consultation hour in Leiden, but there is no national policy.” Patients report to their GP and must inform their contacts themselves. “Because many students are still registered with their parents’ GP, we currently do not have a good picture of outbreaks in student cities.”
For a year now, the number of scabies patients at the GP has been much higher than in previous years – almost doubling, according to the poll by research institute Nivel. After a significant increase last winter, the figures fell in the summer months, but are now rising again. “You could say we are still suffering from the same outbreak,” McCall says. “It is exciting what will happen now that the academic year has started and students are moving back into their rooms.”
McCall calls it “remarkable” that the numbers were so high last winter. “Despite socially restrictive measures and a lockdown, scabies has been able to spread among students.” He says it is speculation how the outbreak started. “Scabies is a blind spot in that sense. Perhaps the numbers are even higher.”
There is no obligation to report, only in the event of an outbreak in healthcare institutions. McNall: „The only figures we have are the figures of the 390 general practices that pass on their data to Nivel. We suspect that people with mild complaints do not always go to the doctor. Or that in a student house one person goes to the doctor and the rest get a medicine from the pharmacy themselves. In addition, it happens that general practitioners mistake scabies for something else, for example eczema.”
Every animal species has its own mange
Mange, or scabies, is caused by a mite. Many animal species can suffer from the animal. Every animal species has its own mange mite; a dog’s mites cannot survive long in humans. The parasite has an oval, white body with eight legs and looks a bit like a spider under the microscope. The females are less than half a millimeter long. The males are twice as small.
On its back, the mite carries brushes and spines with which the female digs tunnels in the epidermis of the human, just below the horny layer, the outer, visible layer of the skin. She eats the cell remains of the cells she destroys along the way. In this way, within a few days, she digs a tunnel just under the skin surface of a maximum of one and a half centimeters that can sometimes be seen on the body as a small line.
The male mites follow the females, and in the corridors they fertilize her, after which the males die. In her four to six week life, the female can lay two to four eggs a day. In total she lays about sixty eggs. From these eggs hatch the larvae that live on the skin’s surface until they grow into sexually mature mites, after which the cycle can start again. Not all young mites survive. On average, a patient carries five to fifteen adult mites.
The parasite has a preference for places such as the palms, wrists, elbows, feet, genitals and the skin between the fingers. Blisters, red bumps and scaling can develop around the corridors. The eggs and faeces of the mite trigger an immune response, causing patients to experience itching that is especially bad at night and when it is hot.
Frequent skin contact
You can contract scabies with skin-skin contact that lasts longer than 15 minutes or with frequent skin contact. You cannot become infected by shaking hands, but you can, for example, sleeping in someone’s bed or using each other’s clothes and towels. Scabies is more common in places where people live close together, such as student houses or care homes. Backpackers who sleep in hostels should use their own sheets, especially if they are in tropical areas where the mites thrive.
A doctor can diagnose it visually, but sometimes the condition resembles eczema. In that case, he can send dander to the lab where lab technicians try to detect the mite under a microscope or do a PCR test to detect the mite’s DNA. “The latter doesn’t happen often,” McCall says. “Recently, in collaboration with the GGD, we investigated how the diagnosis is made, and this is usually based on a clinical picture.”
The condition can be treated well with a permethrin cream or ivermectin pills. Housemates and other close contacts should also smear or swallow to prevent the mite from sticking up. In addition, someone must wash all his clothes, bed linen and towels at a minimum of 50 degrees. Another option is to put all textiles in a sealed bag for at least three days because mites cannot live without their host for more than three days. “With these measures, a patient should be cured in up to two weeks,” McCall says.
Millions of mites
People with weakened immune systems can in rare cases contract the severe form of crustosa scabies. They then carry up to a million mites with them. In this form, others can become infected without physical contact. Patients must be in isolation for treatment.
The treatment of normal scabies only succeeds if everyone in the area adheres to the measures. McCall: “In practice this proves difficult, which is why we regularly see a ping-pong effect. Because you don’t build up immunity, reinfections can happen quickly.”
It is uncertain whether the mite will eventually become resistant to the two agents. “It’s difficult to do research on this because you can’t raise the mites in the lab to expose them to permethrin or ivermectin. It is known that scabies mites in animals can develop resistance.”