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COVID-19 VIRUS DISEASE (Contact) A corona virus that
has been named Covid-19 appeared in central China in late 2019 and subsequently
spread to many parts of the world to cause a widespread pandemic. By May 2020 transmission was determined to
be primarily through human contact, but no studies have been made to
determine if insect vectors might also be involved. It is well established that the mosquito
genera Aedes
and Culex
are vectors of virus diseases that affect humans with symptoms similar to
those of Covid-19. Because many
species in these and other
mosquito genera are
able to reproduce in temporary pools of water they may be considered as
primary suspect candidates for transmission of Covid-19. Studies would involve identifying
non-human alternate hosts such as birds, rodents and bats, the latter being
suspect as an original source of the disease. The insect family Ceratopogonidae and genera Culicoides
and Leptoconops are also known
to spread virus diseases of humans.
These are very tiny insects whose populations often soar to thousands
of individuals in urban and wild areas.
They breed in soils containing organic matter and are extremely
difficult to control. Unlike the
larger mosquito group, these flies are small enough to pass through screened
doors and windows. Repellents applied
repeatedly to skin are the only
effective controls. As of September 2020 many
discussions of these flies may be found on the Internet. An example is a posting by Franziska Sick
et. al. entitled "Culicoides Biting Midges--Underestimated Vectors for
Arboviruses of Public Health and Veterinary Importance. The authors explain that Culicoides
biting midges, are small hematophagous dipterans, which serve as putative
vectors of multiple arboviruses of veterinary and public health importance.
Despite its relevance in disease spread, the ceratopogonid genus Culicoides is
still a neglected group of species, mainly because the major human-affecting
arboviruses are considered to be transmitted by mosquitoes. However, when a
pathogen is detected in a certain vector species, a thorough search for
further vectors often remains undone and, therefore, the relevant vector
species may remain unknown. Furthermore, for many hematophagous arthropods,
true vector competence is frequently only
suspected and not experimentally examined. Thus, the authors
illuminate the general impact of Culicoides biting
midges and summarize the knowledge about biting midge-borne disease agents
using the order Bunyavirales, the largest
and most diverse group of RNA viruses, as an example. When considering only
viruses evidentially transmitted by Culicoides midges,
the Simbu serogroup (genus Orthobunyavirus) is probably
the most important group within the virus order. Its members are of great
veterinary importance, as a variety of simbuviruses, e.g., the species Akabane
orthobunyavirus or Schmallenberg
orthobunyavirus, induces severe congenital infections in
pregnant animals. The major zoonotic representative of this serogroup occurs
in South and Central America and causes the so-called Oropouche fever, an
acute febrile illness in humans. |