Previously, I defended the thesis that the anopheline mosquitoes existing in Portugal (species Anopheles atroparvus) do not, under current conditions, have the risk of transmitting malaria agents, including the parasites that circulate in tropical areas, as these are genetically different from those that existed here and were eliminated at the end of the 1960s (eradicated). That is, they are the same species of mosquitoes, just as they were in the past, but today they do not transmit malaria. In other words, female mosquitoes bite people during their blood meals, but without any danger in relation to malaria. I also highlighted that, among us, the elimination of malaria resulted from the action led by Francisco Cambournac, to whom we owe this achievement.
Vector-borne diseases are not limited to malaria. They are much wider, both in humans and animals, involving multiple vectors: mosquitoes, ticks, sandflies (phlebotomes), fleas, lice, culicoides…
Now, these vectors, when infected, can transmit diseases caused by certain viruses, parasites and certain bacteria. Globally, it is estimated that deaths caused by these infections will be approximately 700 thousand per year. Therefore, they are considered serial killers loose in the environment around us.
On the other hand, many vectors are also involved in the transmission of diseases to animals, causing problems in the food chain and the economy. As an example, I mention the situation identified in Baixo Alentejo, which is faced with the spread of “blue tongue” in sheep and goats.
Now, “blue tongue” constitutes an epizootic (an expression equivalent to an epidemic, but in animals), which, for the past year, has acquired a worrying dimension in Europe, particularly in Portugal. It is caused by the bluetongue virus transmitted by arthropod vectors of the genus Culicoides, which thus causes problems in herds, namely low milk production (cheese production). Like other vector-borne diseases, “blue tongue” is not contagious among animals (ruminants) and, confirmedly, it does not transmit to or infect humans.
However, Culicoides can constitute a human public health problem, due to the transmission of other viral infections, as occurs in Central and South American countries.
Moral of the story: we need to reflect more on the issues associated with the risks that vectors represent, but from the perspective One Health because human health, animal health and the environment remain in constant interaction.
(Continues)
Former Director-General of Health; franciscogeorge@icloud.com