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

2021
Views:

427

Pages:

38
Author:

Neulri

Triatomine bugs, kissing bugs, assassin bugs, or vampire bugs (Triatominae) All medically important species are Central and South America. • vary from 5 to 45 mm in length, but most are 20–30 mm long. • The meso-and metathorax are hidden dorsally by the folded fore-wings, called hemelytra. • • • • hemimetabolous. Small pale nymphs, which resemble adults but lack wings Nymphs and adults of both sexes feed at night on their hosts Many bugs defecate during or soon after feeding, and this behaviour is very important in the transmission of Chagas disease Medical importance • Chagas disease • Trypanosoma cruzi, as South American trypanosomiasis. • Transmission is not by the bite of the insect, only through its faeces. • Chagas disease is a zoonosis so have reservoir hosts. • The triatomine bug itself can also be a reservoir of infection Medical importance • Trypanosoma rangeli • is non-pathogenic in humans. It is transmitted by triatomines, especially by Rhodnius prolixus. • People are mainly infected by the bug’s bite and only rarely by its faeces. Control • by spraying the interior surfaces of walls and roofs/ceilings of houses, out-houses with residual insecticides. • Although fenitrothion (organophosphate) is sometimes used, pyrethroids are the most commonly sprayed insecticides, particularly deltamethrin, cyfluthrin Introduction to mosquitoes Anophelinae (anophelines) Anopheles Culicinae (culicines) Culex  possess only one pair of wings  The hind-wings are represented by a pair of small, knob-like halteres.  slender and small insects, about 3–6 mm in length In females the antennae have short hairs in males, the antennae have many long hairs mate shortly after emergence from the pupa. Sperm from a male enter the spermotheca of a female, and this usually serves to fertilize all eggs laid during her lifetime a female mosquito must bite a host and take a blood-meal to obtain the necessary nutrients for the development of her eggs. This process of blood-feeding and egg-laying is repeated several times throughout the female’s life and is referred to as the gonotrophic cycle. Anophele larva Culicine larva They hang upside down at an angle from the water surface when they are getting air Pupal biology • aquatic and comma-shaped. • The head and thorax are combined to form the cephalothorax, which dorsally has a pair of respiratory trumpets adults Culicine adults Adult Anopheles • Adult Anopheles usually rest with their bodies at an angle to the surface, that is with the proboscis and abdomen in a straight line, or ‘head down bottom up • Culicine adults rest with the thorax and abdomen more or less parallel to the surface Adult biology and behaviour • Species that usually feed on humans are said to be anthropophagic • those feeding mainly on other animals are called zoophagic. • Mosquitoes that feed on birds are sometimes called ornithophagic • Some species feed at any time of the day or night; others are mainly diurnal or nocturnal in their biting habits. • A few species of mosquitoes frequently enter houses to feed and are said to be endophagic • those that bite their hosts outside houses are called exophagic. • Some species rest inside houses during blood digestion and development of the eggs are called endophilic. • In contrast, mosquitoes that rest outdoors are termed exophilic. Mosquito control • Biological control or naturalistic control: 1. Larvivorous fish (Gambusia , warm-water fish) 2. Bacillus thuringiensis and Bacillus sphaericus is killing mosquito larvae • genetic control: 1. Large numbers of sterile males released into field 2. Mosquito is introducing into field that are incapable of transmitting diseases. • Physical control or environmental control • Chemical control like Insecticides: DDT and other organochlorine • Insect growth regulators (IGRs) • Integrated control: means combining control like biological and insecticidal methods • Personal protection: An effective repellent is DEET Medical importance of the genus Anopheles • Malaria: • The most important malarial parasites are Plasmodium falciparum, P. vivax, P. malariae and P. ovale, the mosquito the definitive host, and humans the intermediate host. Important malaria vectors in Iran 1. 2. 3. 4. 5. 6. 7. A.stephensi A.dttali A.fluviatilis A. Culicifacies A.maculipenis A.sacharovi A.superpictus Filariasis • Certain Anopheles species transmit filarial worms of Wuchereria bancrofti, Brugia malayi and Brugia timori, all of which cause filariasis in humans. Arboviruses • The word arbovirus is derived from the term ‘arthropodborne virus’. • Produce viraemia Medical importance of Culicine mosquitoes 1) Biting nuisance 2) Arboviruses  Yellow fever (Flavivirus)  Dengue (Flavivirus)  West Nile virus (WNV) (Flavivirus)  Japanese encephalitis (JE) (Flavivirus) 3) Filariasis: Both bancroftian and brugian filariasis Phlebotomine sand flies (Phlebotominae) Adult flies are often called sand flies because of their colour. Both sexes feed on plant juices and sugary secretions, but females in addition suck blood from a variety of vertebrates • subfamily Phlebotominae • Three genera : I. Phlebotomus in the Old World II. Lutzomyia in the New World III. Sergentomyia  Adults of Phlebotomus and Lutzomyia are difficult to distinguish  Adults are weak fliers and usually disperse 100m or less from their larval habitats • • • • • less than 5mm long hairy appearance, large black eyes long and stilt-like legs the wings are held at an angle of about 40 degrees over the body when the fly is at rest or blood-feeding In males it terminates in a prominent pair of genital claspers female more or less rounded at the tip only females bite Medical importance I. Annoyance (their bites may result in severe and almost intolerable irritations, a condition known in the Middle East as harara.) II. Leishmaniasis caused by Leishmania parasites III. Bartonellosis, Oroya fever or Carrión’s disease (caused by the bacterium Bartonella bacilliformis) IV. Sand fly fevers, three-day fever or Phlebotomus fevers (Sand flies transmit the seven viral serotypes responsible for sand fly fevers