Mosquito on the Fly
Animals that have an external skeleton (instead of an internal spine), a body made of segments, and jointed limbs -- including the likes of insects, spiders, centipedes, and crabs -- are known as arthropods (Gk. arthro: joint, pod: limb).
Mosquitoes are arthropods. And there are 3,500 known species of mosquito. The mosquito acts as vector for a number of organisms -- protozoa, fly-eggs, worms, and viruses -- infectious to humans. Of the viruses carried by arthropods, these are collectively known as arboviruses (i.e. from "arthropod-borne viruses"). This classification as "arbovirus" helps define perhaps the number one human predator -- the virus-bearing mosquito. These highly pathogenic viruses are carried by only a handful of mosquito species.
Dengue* virus is transmitted to humans predominantly by the Aedes aegypti mosquito. The normal cycle of dengue infection is considered to be human-mosquito-human.
Plasmodia parasites, the cause of malaria, are transmitted to humans from the bite of an Anopheles mosquito.
Mosquitoes are arthropods. And there are 3,500 known species of mosquito. The mosquito acts as vector for a number of organisms -- protozoa, fly-eggs, worms, and viruses -- infectious to humans. Of the viruses carried by arthropods, these are collectively known as arboviruses (i.e. from "arthropod-borne viruses"). This classification as "arbovirus" helps define perhaps the number one human predator -- the virus-bearing mosquito. These highly pathogenic viruses are carried by only a handful of mosquito species.
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| Culex pipiens [Image: Wikimedia Commons] |
There is considerable space-time variability to the association between specific pathogen and mosquito specie, although general patterns do exist (see below). And it is true that fellow arthropods such as spiders, amphibians such as salamanders and frogs, fish, and also some other insects think that mosquitoes are quite yummy. But mosquitoes cause much human misery in spreading seemingly endless disease. It is said that half of all humans that have ever lived died from a mosquito bite.
Such bites have included (but not limited to) the transmission of the following pathogens:
Such bites have included (but not limited to) the transmission of the following pathogens:
Dengue* virus is transmitted to humans predominantly by the Aedes aegypti mosquito. The normal cycle of dengue infection is considered to be human-mosquito-human.
Plasmodia parasites, the cause of malaria, are transmitted to humans from the bite of an Anopheles mosquito.
Chikungunya virus is transmitted to humans by Aedes albopictus and Aedes aegypti mosquito.
Yellow Fever virus is transmitted in cities primarily by mosquitoes of the Aedes aegypti species.
Zika virus is transmitted by Aedes mosquitoes, such as A. aegypti and A. albopictus. It has been associated with foetal microcephaly and, importantly, is now believed to also spread directly from person to person via sexual means (surviving up to 8 weeks in human semen).
Murray Valley Encephalitis virus* (MVEV) is maintained in a bird-mosquito-bird cycle, where water birds (e.g. herons and cormorants) provide the natural reservoir of infection while the major mosquito vector is Culex annulirostris.
Lymphatic Filariasis is caused by pathogenic roundworm, mostly Wuchereria bancrofti, from bites of the genus Culex (urban and semi-urban areas), Anopheles (rural Africa), and Aedes (Pacific Islands) mosquito. The B. malayi parasite is transmitted by Mansonia, Anopheles, and Aedes mosquitoes while in east and south Asia it is the anopheline that is predominantly responsible for transmitting infection.
Epidemic Polyarthritis is caused by infection with an alphavirus. Examples include Chikungunya virus and Ross River virus (see above and below) but also Sindbis virus, endemic in Northern Europe, Africa, the Middle East, and Australia.
Murray Valley Encephalitis virus* (MVEV) is maintained in a bird-mosquito-bird cycle, where water birds (e.g. herons and cormorants) provide the natural reservoir of infection while the major mosquito vector is Culex annulirostris.
Lymphatic Filariasis is caused by pathogenic roundworm, mostly Wuchereria bancrofti, from bites of the genus Culex (urban and semi-urban areas), Anopheles (rural Africa), and Aedes (Pacific Islands) mosquito. The B. malayi parasite is transmitted by Mansonia, Anopheles, and Aedes mosquitoes while in east and south Asia it is the anopheline that is predominantly responsible for transmitting infection.
Epidemic Polyarthritis is caused by infection with an alphavirus. Examples include Chikungunya virus and Ross River virus (see above and below) but also Sindbis virus, endemic in Northern Europe, Africa, the Middle East, and Australia.
Rift Valley Fever virus is transmitted by either of two mosquito specie —Culex tritaeniorhynchus and Aedes vexans— but other possible vectors include Aedes caspius, Culex pipiens, Culex antennatus, Culex perexiguus, Culex zombaensis and Culex quinquefasciatus.
Ross River Fever* virus transmission has been associated with tens of vector species, but the major vector is Culex annulirostris in inland areas, Aedes vigilax in northern coastal regions, and Ae. camptorhynchus in southern coastal regions.
St. Louis Encephalitis virus is spread by mosquitoes from the genus Culex, which in turn become infected by feeding on infected birds.
West Nile virus (WNV) maintains itself in nature by cycling between mosquitoes in the genus Culex and certain species of bird.
Japanese Encephalitis virus is, as the name suggests, prevalent in Southeast and East Asia where domestic pigs and wild birds (especially herons) act as reservoirs of infection. The virus is spread predominantly by Culex tritaeniorhynchus and Culex vishnui.
La Crosse Encephalitis virus is a pathogen cycled between the daytime-biting tree hole mosquito, Aedes triseriatus, and amplifier hosts (chipmunks, tree squirrels) in forest habitats.
Eastern Equine Encephalitis (EEE) virus is maintained in nature through a bird—mosquito cycle with two mosquito species primarily involved: Culiseta melanura and Cs. morsitans.
Eastern Equine Encephalitis (EEE) virus is maintained in nature through a bird—mosquito cycle with two mosquito species primarily involved: Culiseta melanura and Cs. morsitans.
Western Equine Encephalitis (WEE) is transmitted by mosquitoes of the genera Culex and Culiseta.
Barmah Forrest virus* is transmitted to humans from bites of infected Aedes vigilax and Culex annulirostris mosquito species. Marsupials are the main viral host, especially possums, kangaroos, and wallabies.
The mosquito (Culicidae) family is divided into two subfamilies (Anophelinae and Culicinae) differing in their significance as vectors. There are 41 described genera: Aedeomyia; Aedes; Anopheles; Armigeres; Ayurakitia; Borachinda; Coquillettidia; Culex; Culiseta; Deinocerites; Eretmapodites; Ficalbia; Galindomyia; Haemagogus; Heizmannia; Hodgesia; Isostomyia; Johnbelkinia; Kimia; Limatus; Lutzia; Malaya; Mansonia; Maorigoeldia; Mimomyia; Onirion; Opifex; Orthopodomyia; Psorophora; Runchomyia; Sabethes; Shannoniana; Topomyia; Toxorhynchites; Trichoprosopon; Tripteroides; Udaya; Uranotaenia; Verrallina; and Wyeomyia.
Mosquitoes can travel up to 2.5 miles per day, feeding on nectar and plant juice. In some 200 species, the female mosquito has certain mouthpart adaptations to enable them to feast on human blood. Through its proboscis, the female mosquito injects anticoagulant saliva into the victim to aid in the drawing of its blood. The saliva is usually the source of the transmitted infection, while the blood meal provides the requisite protein for all but the first batch of mosquito egg production. The female mosquito will then deposit the clutch in shallow water or onto flood-prone damp soil.
To find a host, the female mosquito goes on a search and target mission. A group of humans is searched out through heat sensing and optical recognition. Then, individuals of high chemical attraction (Blood Group O, heavy breathers, heavy bacterial skin colonisation, high body heat, and pregnant) are targeted. Mosquitoes can smell chemicals in human sweat (and breath) and, as is widely believed, do prefer some individuals over others. This attraction is according to the proportions of carbon dioxide, octenol (mushroom alcohol) and other organic compounds (e.g. nonanal, sulcatone) that make up body odor.
Most mosquitos are "crepuscular": preferring to rest in a cool place during the heat of the day, to feed at dawn or dusk. The Asian tiger mosquito is an exception.
*pathogens found in Australia (within a select group from more than 300 specie of mosquito)
The mosquito (Culicidae) family is divided into two subfamilies (Anophelinae and Culicinae) differing in their significance as vectors. There are 41 described genera: Aedeomyia; Aedes; Anopheles; Armigeres; Ayurakitia; Borachinda; Coquillettidia; Culex; Culiseta; Deinocerites; Eretmapodites; Ficalbia; Galindomyia; Haemagogus; Heizmannia; Hodgesia; Isostomyia; Johnbelkinia; Kimia; Limatus; Lutzia; Malaya; Mansonia; Maorigoeldia; Mimomyia; Onirion; Opifex; Orthopodomyia; Psorophora; Runchomyia; Sabethes; Shannoniana; Topomyia; Toxorhynchites; Trichoprosopon; Tripteroides; Udaya; Uranotaenia; Verrallina; and Wyeomyia.
To find a host, the female mosquito goes on a search and target mission. A group of humans is searched out through heat sensing and optical recognition. Then, individuals of high chemical attraction (Blood Group O, heavy breathers, heavy bacterial skin colonisation, high body heat, and pregnant) are targeted. Mosquitoes can smell chemicals in human sweat (and breath) and, as is widely believed, do prefer some individuals over others. This attraction is according to the proportions of carbon dioxide, octenol (mushroom alcohol) and other organic compounds (e.g. nonanal, sulcatone) that make up body odor.
Most mosquitos are "crepuscular": preferring to rest in a cool place during the heat of the day, to feed at dawn or dusk. The Asian tiger mosquito is an exception.
Aedes mosquito
The Aedes genus, including Aedes aegypti (pictured) and Aedes albopictus, are active at dawn and dusk.
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| Aedes aegypti [Image: Wikimedia Commons] |
Aedes mosquitoes such as Aedes aegypti (pictured) are responsible for the spread and transmission of the following human pathogens:
- Dengue Fever
- Chikungunya
- Yellow Fever
- Zika virus
Anopheles mosquito
The anopheles mosquito is a night-time feeder.
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| Anopheles stephensi, full as a goog [Image: Wikimedia Commons] |
The female anopheles mosquito is responsible for the spread and transmission of strains of malarial parasite: the often lethal plasmodium falciparum; plasmodium vivax; plasmodium ovale; and plasmodium malariae.
Culex mosquito
Species of the Culex genus of mosquito are vectors of disease of humans and other animals.
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| A male of the Culex mosquito specie [Image: Wikimedia Commons] |
Culex sp. of mosquito are responsible for the transmission and spread of Filiariasis as well as the following arboviral human infections:
Further Reading: The Anatomical Life of the Mosquito, R. E. Snodgrass. Smithsonian Miscellaneous Collections. Volume 139, Number 8. Washington (1959).
Put that in your proboscis and smoke it.
Put that in your proboscis and smoke it.
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