"Contagious" migration?

Animal migration can in some cases help to reduce or even prevent the spread of diseases, as well as help prevent the development of aggressive "pathogen" strains

One of the most beautiful phenomena in the animal world is migration. Every year billions of animals migrate in groups of thousands to millions. Some of them travel thousands of kilometers for months, others migrate in local ranges from the slopes of the mountains to the plains and valleys.

We all know the migration of the herds of the American buffalo, the migration of birds over our country, the migration of the herds of the wildebeest in East Africa, the migration of the eels in North America, the migration of the sardines in the oceans, the migration of the whales of all kinds, the migration of the goddess fish and the eels and much more. They are all seasonal migrations where millions of mammals, birds, fish or insects gather to move from one geographic area to another.

Migration is dictated by weather changes, changes in the length of the day, lack of food or water, multiplicity of parasites, reproductive needs (or evolutionary "tradition" due to reasons that were and are not).

In the last hundred years, the human population has caused fatal damage to migration routes, by physically blocking them: by fences, settlements, roads, etc., by changing environmental conditions, drying up bodies of water that were used as "gas stations", cutting down forests or damming rivers.

In addition to this, it turns out that global warming causes migrating populations to shorten the duration and range of migration to the point of complete cancellation, it turns out that migration or its cessation has a direct effect on the spread of diseases.

While migrating, the migrants pass through different habitats in which many different "pathogens" are present. Many different species in large numbers gather and use the same rest areas and "refueling" stations, a gathering that allows diseases to spread.... Therefore, it is common to think that migration is a factor in the spread of diseases.

In southern Africa, fences were built to prevent the migration of wildebeest (antelopes) in an attempt to stop the spread of foot-and-mouth disease. The birds, recently the migratory birds are being blamed for spreading "West Nile fever" along the eastern coasts of the USA!

Are the blame shifting?

Researchers at the University of Georgia Odum School of Ecology publish their findings in "Science", according to the findings: "Animal migration can in some cases help reduce the spread of diseases, as well as help prevent the development of "aggressive pathogen" strains ".

"Migration can help limit and prevent the spread of diseases." Parasites (causes of diseases) grow and reproduce in periods that correspond to the presence of their carriers in a certain environment/habitat, migration is an "escape" from the concentrations of parasites.

When the carriers are gone, the number of parasites falls so that when the migrants return they find a habitat/environment (relatively) free of parasites and diseases, long migration periods cause infected/diseased individuals to die before they have time to transfer/infect the migrating population.

The more violent the cause of the disease (the patient will die faster), the more likely it is that the patient who dies on the way will not infect his neighbors, therefore the more violent the cause of the disease, the faster migration will neutralize it.

The researchers carried out most of their work in the environment of the monarch butterfly Danaus plexippus whose migration route from Canada to Mexico lasted four generations and thousands of kilometers. Whereas in other parts of the world the Danaids migrate short distances and for short periods.

The moths "carry" a single-celled protozoa parasite that harms the butterfly, different populations of moths in different places gave researchers an excellent opportunity to test the distribution of the parasite.

Indeed, it turns out that the longer the migration route, the less the distribution of the parasite. The highest distribution of the parasite occurs in non-migratory populations. This is both because infected butterflies do not complete migration and also because of the remaining possibility for the development of a parasite population in a stationary butterfly population.

In other words, the migration of the terns is important for maintaining a healthy population, a conclusion that can be applied to many species that migrate.

The migration of the falcon, like other migrations, is disrupted by human activities, in addition to the disturbances (mentioned above), the increase in domestic animal populations and in agricultural areas increases the possibility for pathogens to break out and spread and "jump" between different species, another factor that changes the course of migration is global warming. In many cases, species whose impulse to migrate was a drop in temperature below a certain minimum are "exempt" from migrating,

The migration "strategy" developed over millions of years as a response to pressures such as food and water availability, predators, temperature changes and disease-causing parasites ("pathogens"), this "strategy" is disrupted today by: blocking migration routes, damage to rest stations and Tidaluk", an increase in the density of domestic animal farms, an increase in agricultural areas and again... global warming.

All these factors (and others) constitute barriers that interfere to the point of stopping the migration, any change in the "strategy" can cause changes in the distribution of diseases and their causes, according to the researchers: "By placing diseases in an environmental context, it is possible to distinguish the continuity and distribution of the causes - a "classic" example of ecology of diseases at its best".
Therefore it is necessary to study and understand the activity of the generators of epidemics in migratory populations as well as the effect of human activity on those generators. Research and study that will enable correct decisions on conservation and environmental management issues, research that will enable prediction and mitigation of epidemic outbreaks.

In many cases migrating species are blamed for spreading diseases, it turns out that most of the cases examined show the opposite.... People are responsible for creating conditions that allowed the spread of diseases in migratory species!

After all, it has already been written and said that the time has come that instead of controlling the environment for the sake of the human population, there will be control of the human population for the sake of the environment.

to the notice of the researchers