University:
American Career College
Course:
NURS115 | Intermediate Medical
Academic year:

2021
Views:

216

Pages:

41
Author:

Neulri

Black flies (Simuliidae) Medical importance 1. Annoyance 2. Onchocerciasis (The S. damnosum species complex is widespread in tropical Africa) 3. Mansonella ozzardi (is a filarial parasite of humans that is usually regarded as non-pathogenic) Tsetse flies (Glossinidae) Medical importance • All Glossina species are potential vectors of African trypanosomiasis to humans. There are two subspecies of trypanosomes causing sleeping sickness in humans, namely 1. Trypanosoma brucei gambiense 2. T. brucei rhodesiense. house fly (Musca domestica) the stable fly (Stomoxys calcitrans) • worldwide distribution. • House flies can be vectors of helminths, faecal bacteria, protozoans and viruses, resulting in the spread of enteric diseases (e.g. dysenteries and typhoids). • The stable fly is a biting pest. Larvae, known as maggots, have a small head followed by an 11-segmented cylindrical body The stable fly (Stomoxys calcitrans) • known as biting house flies or, in the USA as dog flies • Both males and females take blood-meals from wild and domesticated animals Flies and myiasis Myiasis is the invasion of organs and tissues of humans or other vertebrate animals by fly larvae, which at least for some time feed on the living or dead tissues Myiasis may be • Accidental: Although the larvae may survive for some time in body, no flies are specially adapted to cause myiasis in humans. • In obligatory myiasis it is essential for the fly maggots (larvae) to live on a live host for at least a part of their life. • Calliphoridae, Sarcophagidae and Oestridae. • In facultative myiasis larvae are normally freeliving, but under certain conditions may infect living hosts. Maggot therapy • Several commercial companies breed colonies of the flies, • the fly eggs produced are given an antiseptic bath, • the resulting first-instar larvae are then placed on a patient’s wound. • Fly maggots most frequently used are those of Lucilia sericata. Cockroaches belong to the order Blattaria • brown or black, • 10–50 mm long, • flattened dorsoventrally, • Cockroach mouthparts are developed for chewing, they cannot suck blood. • Both sexes have two pairs of wings. cockroaches rarely fly. The most important medically are: 1. Blattella germanica (the German cockroach), 2. Blatta orientalis (the oriental cockroach) 3. Periplaneta americana (the American cockroach) Eggs are laid encased in a brown bean-shaped case called an ootheca , which can contain 5–50 eggs but typically 12–40. Cockroaches have a hemimetabolous life cycle. Life cycle • Cockroaches like warmth, • they are found in almost any dark place • Cockroaches are nocturnal and are rarely seen during the day unless they are disturbed from their hiding places. • They are eating any type of food. • They can live for 5–10 weeks without water and for many months without food Medical importance • Allergies • Infectious agents: There is little doubt that cockroaches contribute to the spread of several infections, mainly intestinal ones. • Sometimes they may possibly be more important as mechanical vectors than house flies. Control • good hygiene • Boric acid powder (borax) still remains a very safe and useful chemical insecticide THE CHELICERATA • • • • possessing chelicerae and pedipalp, lacking antennae, having four pairs of legs as adults a cephalothorax and abdomen. Class: arachnida Order: Acarina Order: Araneida Order: Scorpionida Scorpion predatory have eight legs easily recognized by the pair of grasping pedipalps the narrow, segmented tail, often carried in a characteristic forward curve over the back, ending with a venomous stinger. Scorpions range in size from 9 mm to 23 cm Araneida includes all spiders A spinneret is a silk-spinning organ of a spider or the larva of an insect. worldwide distribution Mites Order Acarina Ticks  ticks differ from mites in having a toothed hypostome,  adult ticks are also much larger than mites. Ticks have eight legs, are divided into two main families: 1. the Argasidae (soft ticks) 2. the Ixodidae (hard ticks). Soft ticks (Argasidae) The medically important soft ticks belong to the genus Ornithodoros. • flattened dorsoventrally, • 8–13 mm long and usually roundish to oval in outline. • There is no scutum (dorsal shield) as is found in ixodid (hard) ticks. • The mouthparts, termed the capitulum, or ‘false head’, are situated ventrally and are not visible dorsally in the nymphs and adults. • Males and females look very similar • both sexes feed on blood and can consequently be disease vectors eight-legged nymphs six-legged larvae A blood-meal is essential for egg production, in argasids feeding is mainly nocturnal. Medical importance • Tick-borne relapsing fever (species of Borrelia) • Transovarial transmission • Transstadial transmission • In transstadial transmission, a larva might become infected by feeding on an infected host and pass the spirochaetes to the nymphs and adults, or the infection might start with a nymph and be passed to subsequent nymphal instars and the adults. In all cases transovarial transmission can follow. • Q fever • Viruses (More than 100 arboviruses are transmitted by ticks) • Tick-bite allergies and tick paralysis (allergies such as itching, skin rashes, fevers, vomiting and diarrhea) Control • Houses infested with argasid ticks, such as Ornithodoros species, can be sprayed with insecticides such as the carbonates carbaryl and propoxur

Black Flies (Simuliidae)

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