MEDICAL ENTOMOLOGY: Vector of Diseases

MEDICAL ENTOMOLOGY NUR3107 BASIC MICROBIOLOGY, PARASITOLOGY AND IMMUNOLOGY By Dr Norashiqin Misni, JMP MOSQUITO  Aedes spp – vector for dengue,filariasis  Anopheles spp – vector for malaria, filariasis  Mansonia spp – vector for filariasis  Culex spp – vector for...

MEDICAL ENTOMOLOGY NUR3107 BASIC MICROBIOLOGY, PARASITOLOGY AND IMMUNOLOGY By Dr Norashiqin Misni, JMP MOSQUITO  Aedes spp – vector for dengue,filariasis  Anopheles spp – vector for malaria, filariasis  Mansonia spp – vector for filariasis  Culex spp – vector for filariasis  Order : Diptera. Suborder : Nematocera. Family Culicidae: 3,500+ species; 75% in tropics & subtropics Subfamily : 1) Anophelinae: Genus: Anopheles. The only vector for malaria and vector for filariasis. Introduction 2) Culicinae: Genus: Aedes, Culex, Mansonia Main vectors of arboviruses and filariasis 3) Toxorhynchitianae: Genus: Toxorhynchites Don’t bite , not disease vector Anatomy of the mosquito 5 Characteristic of the mosquito  Developmental stages of spp (above) and Anopheles spp (below) Eggs Larvae Pupae adult Culex spp (above) and Mansonia spp (below)  Newly emerged adults near breeding site Life cycle of the mosquito males in swarms, able to mate ~24 h after emergence usually, females mate once only Males feed only on sugar - nectar, fruit exudates etc. Females - need blood meal to produce eggs- hence route for entry of blood-borne pathogens will also take sugar meals One egg batch after each blood meal Adults short-lived degenerate -> at first. Mites and carrion gases and volatile organic brownish - black content of Butyric acid beetles feed on dry compound. (advanced stage) abdominal cavity produced -> cheesy skin, hair and larvae Odor of decaying exposed odor develops. of other insect flesh. Associated with Ventral surface insect activity (flies/ mouldy from beetles) fermentation STEP IN ESTIMATING PMI WITH INSECT LARVAE Insect larvae present on the dead body can provide evidence for PMI estimation up to 1 months. Correct species identification. Age of the larvae has to be determined – measuring the length and dry weight of the oldest larvae and comparing it with the reference data. Thermal history –temperature at the death scene.  FACTORS AFFECT THE INSECT SUCCESSION AND DECOMPOSITION Season (daily temperature and humidity) lower temperature -> slow down the activity of blowflies; dry environment -> leading to mummification Sun exposure -> effect on stage of decomposition Access to the body/corpse : - buried body -> limit the availability of certain insect to colonize. - brightly lit area -> inhabited by Lucilia illustris fly; - shaded area -> Phormia regina fly Clothing : - loose fitting covering -> aid in colonization of insects. - Wearing heavy jacket -> slow down the decomposition stage and colonization of insects. Pesticides -> slow down the insect colonization Drugs – cocaine can speed up the insect development; arsenic will slow down the insect development. ENVENOMATION OF SNAKES  Classification of snakes Colubridae Viperidae Phyton (majority are not venomous Pit Viper except boomslangs) (venomous) Elapidae Cobra (venomous) 40 Colubridae No Majority coronoid are non- bones of venomous the lower except jaws boomslang Presence Highly of Duvernoy’s Colubridae flexible glands jaws Duvernoy's glands secrete a complex mix have Body of chemicals, which may act vestiges completely as a slow-acting venom or of the covered in digestive aid hind limbs scale 41  Unlike the vipers and elapids, the venom of colubrids has little @ no impact on human beings. Opisthoglyphous : small, grooved fangs are located in the back of the upper jaw, unlike those of vipers and elapids, which are located in the front. non-venomous colubrids : use fangs to puncture egg-shells or similar food Genus Baiga : produce medically significant bites. The boomslang and the twigsnakes have caused human fatalities. solenoglyphous (hollow) fangs Vipers 42 43 Viperidae Keeled scales rattlesnakes A triangular- Venemous snake shaped head Moccasin snakes Viperidae The fang can be folded and tip The head that is inwards, when distinct from the the mouth is body closed Azemiops faea (Fea’s viper) A single pair of a long, hollow, venom injecting fangs causus snakes 44  Viperid venoms contain an abundance of protein-degrading enzymes, called proteases. Proteolytic venom : 1) used for defense and to immobilize prey, as with neurotoxic venoms 2) have a digestive function. symptoms : pain, strong local swelling and necrosis, blood loss from cardiovascular damage complicated by coagulopathy, and disruption of the blood clotting system. Death is usually caused by collapse in blood pressure. Have haematoxic and myotoxic venom that produce damage at the bite site, including the necrosis of the tisues viperid bite is often a very painful experience and should always be taken seriously, even though it is not necessarily fatal proper treatment, a bite can still result in a permanent scar, and in the worst cases the affected limb may even have to be amputated 45 Elapidae Venomous Elapidae Hollow, Long, slender permanently bodies with erect, short fang smooth scale (proteroglyphous) 46  Coral snake Krait snake Death adder snake Olive sea snake 47 Venom Most elapids snakes are venomous and many are potentially death!! Venom : neurotoxic (act on nerves system) which is more dangerous Black mamba Snake than vipers (proteolytic) world's most deadly snakes!!! -death within 20 minutes - Venom : neuro and cardiotoxin Inland Taipan Snake 48  Treatment 1. Keep the person calm. Restrict movement and keep the affected area below heart level to reduce the flow of venom. 2. Remove any rings or constricting items, because the affected area may swell. 3. If the area of the bite begins to swell and change color, the snake was probably venomous. 4. Monitor the person's vital signs -- temperature, pulse, rate of breathing, and blood pressure -- if possible. If there are signs of shock (such as paleness), lay the person flat. 5. Get medical help right away. 6. If possible, make note of the color, shape, and size of the snake. This may help with treatment of the bite. Do not waste time hunting for the snake. 7. If the snake is dead, be careful of the head -- a snake can actually bite (from a reflex) for several hours after it's dead. 49 50 51 To prevent snake bites: Avoid areas where snakes may be hiding, such as under rocks and logs. Avoid picking up or playing with any snake unless you have been properly trained. Don't provoke a snake. That is when many serious snake bites occur. Tap ahead of you with a walking stick before entering an area where you can't see your feet. Snakes will try to avoid you if given enough warning. When hiking in an area known to have snakes, wear long pants and boots if possible. 52 POISONOUS ARTHROPODS Scorpion Order Scorpiones or Scorpionida), elongated arachnid species characterized by a segmented curved tail tipped with a venomous stinger at the rear of the body and a pair of grasping pincers at the front. Scorpion stings may cause of cutaneous condition : pain, paresthesia, and swelling Deliver the sting using Telson. The venoms of more than 1,200 other species are not deadly. These species, however, produce hemotoxins that cause mild to strong local effects, including edema, discoloration, and pain The sting is often less painful than that of a bee, and victims fully recover in minutes, hours, or days.  About 25 species in eight genera possess venoms capable of killing people. Scorpion venoms : neurotoxic Consist of small protiens that affect nerve system and interfere with neurotransmission. They used venom to kill @ paralyze their prey so that it can be eaten Fast acting, allowing for effective prey capture The effect can be severe SPIDER The are two types of venom : neurotoxic and cytotoxic venom Neurotoxic : Attack nerves system. For examples Black widow/ Redback spiders (Latrodectus species) Cytotoxic : cause damage to the tissue such as blister and lesions such as Recluse Spiders. Neurotoxic venom kill more quickly than cytotoxic. Stinging insect Belong to the genus Hymenoptera, consist of bees, wasps and ants. Stings are painful because they inject venom that contains specific chemicals that cause an immediate burning sensation. The venom also contains chemicals that are involved in allergic reactions. Bee Sting Honey bees are a medical risk because they can be very common even in urban areas, people commonly come in contact with them, colonies can consist of many thousands of workers, workers sting if their colony is disturbed, and their venom contains several chemicals involved in allergic reactions. In sensitive individuals, a dangerous systemic reaction may occur, going beyond redness and hives to involve airways and circulation. These symptoms can be life threatening and medical assistance should be sought immediately. Anaphylaxis : Rapid swelling around the eyes, lips, tongue, or throat. Trouble breathing or swallowing. Wheezing or hoarseness. Treatment Paederus can caused paederus dermatitis. Characterized by a sudden onset of erythematobullous lesions. This beetle does not bite or sting, but accidental brushing against or crushing the beetle over the skin can provokes the release if its coelomic fluid, which contain paederine, a potent vesicant agent.