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Head lice – more common than you think

Head lice – more common than you think

With the beginning of every school year, there inevitably comes a series of reports on the rising tide of head lice infestations. It may seem that the advances we’ve made in sanitation and medicine should eliminate the presence of such parasites from our daily lives. How come we are still experiencing these ‘head lice outbreaks’?

The 20th century has brought us the long-awaited decline in incidence of infectious and parasitic diseases. Indeed, the improvements in our health care and quality of life have drastically altered the proportions between infectious diseases and other serious illnesses. In Poland, for instance, the former cause less than 1% of total deaths, while cardiovascular diseases, cancer, and external factors make up as much as 80% of them. In the past, diseases caused by bacteria, viruses and parasites decimated entire populations during epidemics, but vaccination and widely available medicine helped to prevent this.

However, despite global trends, the incidence rates of some diseases often cause concern, and that is precisely the case with pediculosis (also known as lousiness) caused by head lice. In 2008, the Polish National Institute of Public Health – National Institute of Hygiene stopped collecting data on pediculosis, since head lice were not found to transmit any dangerous disease. Until that point, the incidence rate of pediculosis was higher every year. Today, though we have no official data to speak of, we know that the problem is still there. Why is it that despite good sanitation and broad access to insecticides, lice are still troubling us?

Based on an analysis prepared by Dr Magdalena Kozela from the JU MC Chair in Epidemiology and Population Studies, we’ll take a closer look at the returning head lice issue.

Man’s faithful companion

First, we need to know exactly what pediculosis is. And the answer is: it’s the skin lesions caused by the bites of head lice (Pediculus humanus capitis) – tiny parasitic arthropods that may find their way onto our hair. An individual louse with access to human blood may live about one month, laying as much as 300 eggs (called ‘nits’). Without it, it dies in roughly 36 hours. Its bites are very itchy, often described as similar to poking the scalp with hot needles. When scratched, these areas become covered with minuscule lesions (known as ‘excoriations’) that can lead to other infections, as they are a way for bacteria to enter our bodies.

Incidence rate of pediculosis in Poland (per 100,000 people) according to the National Institute of Public Health – National Institute of Hygiene. Data compiled by Dr Magdalena Kozela

Lice have probably existed way before evolution turned us into Homo sapiens. The oldest fossils of nits found on mammalian hair come from Baltic Sea amber dated back to Eocene. If our ancestors were hosts for lice for such an extremely long time, why are these tiny pests so overwhelmingly associated with poor hygiene and poverty?

In the past several centuries, our knowledge of medicine was very limited, which resulted of dangerous epidemics. Some of them, like typhus, plague, and relapsing fever, were carried by lice and caused the deaths of thousands upon thousands of people. Just a single person neglecting their hygiene could therefore potentially infect a large number of others. In 1918, Arkadiusz Antoni Puławski, a Polish doctor, observed this effect on soldiers fighting in the Great War. As lice proliferated among soldiers and the homeless, in destitute and war-torn areas, people began to see them as poor man’s parasites. In time, most of the diseases carried by lice were eliminated, but they stayed the same – just as for millions of years, except now without dangerous pathogens.

Parents’ responsibility

How many cases of pediculosis are there today? We can’t be too sure. Since it’s no longer registered by the National Institute of Public Health, we can only assess it on the basis of media reports, demand for insecticides, and polls conducted by independent institutions. In 2012, a survey carried out in nearly 900 schools has proven that as much as 45% of children have had contact with head lice.

There is one factor that further aggravates the problem. Since pediculosis is no longer considered an infectious disease, parents are not forced to keep their sick children out of schools. This decision is left entirely to parents or guardians, which means they might risk other children’s well-being.

Do not shave

Unfortunately, combating pediculosis is hindered by the fact that it’s stereotypically associated with poverty and poor hygiene. Although research suggests that it’s more prevalent in rural areas, the first and foremost rule of infectious disease epidemiology is that the incidence rate is directly related to the number of carriers. Basically, the more sick people there are, the higher the risk for healthy ones, regardless of socio-economic status, sex, place of residence, and hygiene. The most important factor is the intensity of contact between people  – and in the case of school children, it’s very high.

Lack of awareness and proper education are the two main dangers when it comes to head lice transmission. Additionally, some research projects point out that pediculosis is more harmful from the psychological rather than physiological standpoint. To escape social stigma, the problem is often hushed up or played down. False information, such as the alleged necessity of shaving one’s head, also contributes to the problem. In reality, based on our current medical knowledge, that would only make it worse, since shaving may damage the scalp and increase the risk of other infections, prolonging recovery time.

The responsibility for the spread of pediculosis lies with parents and guardians. In order to make it easier for them, we need to prevent stigmatisation of people affected by the disease and spread reliable information that will allow people to effectively fight it. Only in this way we can combat the rising incidence rate of pediculosis, a disease which is now perceived much differently than just one hundred years ago.

Original text:

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