The pandemic, in a strange, but quite expected way, affected the spread of parasitic infections. At least now this is known from the example of Argentina, where they conducted a study to find out how lockdown affected the situation with head lice. Its prevalence among children fell from 70% to 44% in Buenos Aires. But at the same time, the number of scabies mites began to grow.
The work of Argentine scientists was the first and so far the only one to study head lice infestation during a pandemic.
Total – lice have been living with us since the beginning of time, and are still found not only in slums, but also in quite civilized countries. According to the WHO, several billion people around the world are at constant risk of contracting head lice. Pediculosis is the most common disease, regardless of the level of economic development of the country. For example, in Denmark, “lousy subbotniks” are regularly organized, during which, so to speak, the general disinfection of the population takes place. Head lice is one of the most common childhood parasitic diseases in the world. By the way, there are still countries in the world where lice are considered a sign of well-being, and therefore they do not even fight against them. In open sources, you can find information that in the United States, up to 19% of schoolchildren carry head lice every year, in the Czech Republic – more than 20%. The increase in “lice” is due to the fact that these insects quickly acquire resistance to insecticides – the means with which they are poisoned.
However, if earlier we actively traveled and brought lice from other countries, then in a pandemic this method of transferring parasites has practically lost its relevance. And in countries where they have introduced and continue to impose severe covid restrictions, including the closure of children’s educational institutions, it has become difficult for lice to survive at all. After all, lice infestation occurs only with close contact, “head to head”, which excludes social distance.
According to statistics, lice are most common among children of preschool and primary school age, and in girls they occur 2-4 times more often (according to Argentine researchers, this is explained not only by the length of the hair, but also by the behavioral features of girls who are more prone to tactile contacts). But the introduction of social distance has played a useful role not only in preventing COVID infection, but also in reducing the prevalence of head lice.
At the beginning of the pandemic in Argentina, as in many other countries of the world, a strict quarantine was declared, which lasted for 180 days (this is the longest quarantine among the countries of South and North America). Children switched to telecommuting – and voila! The questionnaire survey showed that in the majority of children who were diagnosed with head lice before the lockdown, the disease turned into a mild form. As the authors of the work note, the situation is consistent with a well-known feature of almost all parasite-host systems: most hosts carry a small number of parasites. But the main finding is that the overall prevalence of head lice after the introduction of the lockdown dropped from 69.6% to 43.9%. It is curious that the incidence has decreased exclusively in families with 1-2 children. Where there are more than three of them, quarantine had almost no effect on lice. But factors such as the number of rooms and family members living together in the same area did not have any effect on the situation.
In general, there is nothing that defies logical explanation in this situation: the children have become less in contact, which means that they are less likely to become infected with lice. But in the same article, other data are given, which are already more difficult to explain: as soon as the prevalence of lice dropped sharply, an explosive increase in the number of diseases caused by scabies began immediately! By the way, not only in Argentita: similar reports came from Turkey. The authors of the study still found an explanation: scabies mites spread best in unsanitary and overcrowded conditions. And, due to the fact that the pandemic has led to the closure of many jobs in cities, people began to move en masse to villages where itch itching is more common. Another factor is that overcrowded hospitals in developing countries have also become hotbeds of scabies.
There are no such studies in Russia, and they are unlikely to be planned. However, before the pandemic, lice had become commonplace even in elite schools. The Rospotrebnadzor of the Russian Federation notes that the dynamics of the incidence of head lice in the country over the past decade has a tendency to decrease since 2011. And yet this figure is still quite high. In 2019, 193 954 cases of pediculosis were registered (the incidence rate was 132.09 per 100 thousand of the population), including 53 528 cases among children under the age of 14 (the indicator was 206.83). In the pandemic year 2020, the overall rate of head lice incidence in the country has really decreased: it amounted to 123.68 per 100 thousand of the population (a total of 181 524 cases). And among children under 14 years of age, it decreased and completely seriously, almost by half: in 2020, 29,042 cases of the disease were registered (indicator – 111.96).
Moscow is still among the leaders (for some reason, the incidence in it for the pandemic year of 2020 increased from 1008.26 cases per 100 thousand population to 1138.20). In the Tomsk region, the indicator fell from 193.07 to 104.79; in Arkhangelsk from 146.88 to 92.76; in Magadan – from 134.58 to 60.42, in Astrakhan – from 122.66 to 92.76, in Sakhalin – from 112.06 to 62.58.
In January-May 2021, 61,677 cases of head lice were registered (42.02 per 100 thousand of the population), including among children under the age of 14 – 9,964 cases (indicator – 38.41).
Every fourth carrier of head lice in Russia is a homeless person. The prevalence of head lice among students of general education organizations averaged 0.03% across the country, 0.02% among vacationers in health institutions, 0.01% among those living in boarding schools for the elderly and disabled, and 0.03% in orphanages. …
However, experts note that official Russian statistics are just the tip of the iceberg. Many children’s institutions do not report the detection of lice to the sanitary services, so as not to damage their image. And the majority of people, finding “gifts” in their heads, do not go to doctors: they instantly run to the pharmacy for “poisons” from lice or, worse, try to heal themselves with folk methods.
Meanwhile. If you delve into the history of the evolution of parasites, a lot of interesting things will be revealed. For example, according to one of the hypotheses, it was because of these parasites that many millennia ago our ancestors had to part with their body hair. And if we take into account that head and body lice began to be separated about 170 thousand years ago (this was already established by genetics), it can be assumed that it was in those years that people got clothes. Just due to the fact that people became cold without wool.
The discovery of head lice on the hair of the mummy of the King of Naples Ferdinand II of Aragon (1467-1496) testifies to the wide spread of head lice in the Renaissance even among the representatives of the upper class. During the war of 1812, we infected many French people with lice.
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