1. MEDICAL ENTOMOLOGY (INTRO).pptx

MEDICAL ENTOMOLOGY R. C. Brenyah  INTRODUCTION MEDICAL ENTOMOLOGY is the science that deals with the relationship of INSECTS, ARACHNIDS and other ARTHROPODS to the causation of pathological conditions in man or the transmission of organisms that are responsible...

MEDICAL ENTOMOLOGY R. C. Brenyah  INTRODUCTION MEDICAL ENTOMOLOGY is the science that deals with the relationship of INSECTS, ARACHNIDS and other ARTHROPODS to the causation of pathological conditions in man or the transmission of organisms that are responsible for such pathological conditions.. Role of arthropods may be; The causal agent themselves, e. g. mites Intermediate host, e. g. beetles Vectors, e. g. mosquitoes  ARTHROPODS THAT IMPACT ON HUMAN HEALTH The role of Arthropods in spreading Pathogens Medical Entomology is really an important science and involves the knowledge of many other Sciences, e. g. bacteriology, virology, parasitology, chemistry etc. As MEDICAL PERSONNEL, you will then have knowledge of: ADULT LONGEVITY, FEEDING BEHAVIOUR, SEASONAL ABUNDANCE and PREDILECTION FOR HUMAN BLOOD There is the need to study the taxonomy, biology and ecology of the vectors to enable Scientists to; Devise control strategies Break transmission cycle of the disease To get a better insight to the epidemiology of the disease  INTRODUCTION With this knowledge, you can; ADVICE PROMOTE PUBLIC AWARENESS CARRY OUT RESEARCH MONITOR AND REDUCE INSECT POPULATIONS MAINTAIN AREAS FREE OF INSECTS GENERAL IMPACT OF INSECTS ON MAN TOURISM RECREATION LAND DEVELOPMENT INDUSTRY AND AGRIC DEVELOPMENT DEPRESSES LAND VALUE ADVERSELY AFFECTS FOREST PRODUCTS, AGRIC PRODUCTS AND MINING ACTIVITIES, COASTAL ACTIVITIES etc, etc Who needs Medical Entomologists Scientists Farmers/Agriculture Industry/ Chemical …… pest control Customs Inspectors ….Quarantine Military Police……Forensic entomology/ Criminology Homeowners Doctors/ Veterinary & disease control Artists/Writers  OBJECTIVES PREVENTION ERADICATION CONTROL, if eradication is not possible Therefore, that means reducing Population levels of insects to acceptable numbers Therefore pest control and eradication in terms of improving standards of living comfort and mental health.  VECTOR-BORNE DISEASES Vector-borne diseases constitute some of the most severe health problems in the African Region, especially in the Rural areas where the environment is hostile to man but conducive to insects Inadequate sanitation and behaviour patterns of the population itself contribute to provide favourable conditions for vector-borne diseases. Climate Change also affects Insect populations  DISEASES - HARMFUL EFFECTS HIGH MORTALITY RATE HIGH MORBIDITY RATE This impedes socioeconomic development, e.g. malaria, guinea worm, trypanosomiasis, onchocerciasis, YF, guinea worm, schistosomiasis etc. Man has always been aware of the medical importance of insects E. g. Pharaoh and flies, YF control dates as far back as 1900 Biblical reference – History is endless  DISEASES - HARMFUL EFFECTS Always work for Medical Entomologist due to resurgence of pest resistance to insecticides Insecticides - takes a long time to produce and test As a result, there is always the need to MONITOR INSECT POPULATION levels to forestall any outbreaks  WAYS IN WHICH ARTHROPODS RELATE TO HUMAN AND ANIMAL HEALTH A. ARTHROPODS AS DIRECT AGENTS OF DISEASE OR DISCOMFORT 1. ENTOMOPHOBIA/ARACHNOPHOBIA: Irrational and persistent fear of insects/arachnids infestation or attack The victim is convinced he is being attacked – Unpleasant, causes acute annoyance that leads to NERVOUS DISORDER with sensory HALLUCINATION. It can be considered as a real pathological condition If there is no actual arthropod it is referred to as DELUSORY PARASITOSIS “fear of the unknown”  WAYS IN WHICH ARTHROPODS RELATE TO HUMAN AND ANIMAL HEALTH ENTOMOPHOBIA/ARACHNOPHOBIA Phase 1: Anxiety sense of doom Phase 2: Panic attack rapid heart beat Phase 3: Motor response, running away or freeze Is it a genuine respect for damaging potential of insects? It is a wise thing!! ( Excessive or Unrealistic fear) Conditioned behaviour from direct experience Spiders/Scorpions are the most feared. WAYS IN WHICH ARTHROPODS RELATE TO HUMAN AND ANIMAL HEALTH 2. ANNOYANCE AND BLOOD LOSS Difficult to estimate annoyance Very irritating, e. g. ants , bees disrupt picnics and camp ground activities Blood loss for humans not so significant as it is for livestock 3. ACCIDENTAL INJURY TO SENSE ORGAN: EYE/EAR Eye moths: Lachrymal secretions - Inflammation and bacterial contamination 4. DERMATOSIS/ECTOPARASITOSES WAYS IN WHICH ARTHROPODS RELATE TO HUMAN AND ANIMAL HEALTH 5. ENDOPARASITOSES eg MYIASIS, JIGGER FLEA An invasion of tissues and organs of man eg. by Dipterous larvae. This often leads to secondary infection. 6. ENVENOMIZATION/ALLERGIES Poisonous chemicals (toxins) produced by insects that most people are hypersensitive to eg from wasps and bees Chemicals can be found in saliva, body fluids and secretion, faeces of insects WAYS IN WHICH ARTHROPODS RELATE TO HUMAN AND ANIMAL HEALTH 6. ENVENOMIZATION/ALLERGIES Poisonous chemicals produced by insects that most people are hypersensitive to, e.g. wasps These chemicals cause a variety of medical complications in vertebrates – can even cause death Allergies to saliva and insect waste – faeces Also enzymes proteases, hyaluronidase, acetylcholine that affects the autonomic nervous system STINGS: Bees, Wasps usually bite as a defensive mechanism BITES: Spiders, Ticks, Ants  Venoms cause NEUROTOXICITY - paralysis of neurons NECROSIS - tissue burns pain and death HYMENOPTERA eg bees, wasps, ants LEPIDOPTERA eg some butterflies and moths - have URTICATING hairs that contain toxins, COLEOPTERA – blistering beetles – produce CANTHARIDIN causes blisters and vesicles on skin CENTIPEDES also bite, MILLIPEDES produce fluids that burn WAYS IN WHICH ARTHROPODS RELATE TO HUMAN AND ANIMAL HEALTH B. ARTHROPODS AS VECTORS OR INTERMEDIATE HOST An insect is said to be a VECTOR when it transmits PATHOGENS OR PARASITES from one animal/man to another animal/man. 1. MECHANICAL CARRIER Pathogens undergo NO morphological change or multiplication. Transmission is accidental and these pathogens do not rely solely on a particular fly for transmission or to complete their life cycle WAYS IN WHICH ARTHROPODS RELATE TO HUMAN AND ANIMAL HEALTH 2. OBLIGATORY VECTORS/CYCLICAL TRANSMISSION This involves some degree of development within the arthropod and the pathogen may undergo multiplication, morphological change and migration to the correct state and place for transfer. 3 TYPES i. CYCLOPROPAGATIVE TRANSMISSION Pathogenic organism undergoes cyclical change and multiplies E. g. malaria/ plasmodium sp, Sleeping sickness/trypanosomes WAYS IN WHICH ARTHROPODS RELATE TO HUMAN AND ANIMAL HEALTH ii. CYCLODEVELOPMENT TRANSMISSION Pathogenic organism undergoes cyclical change – it develops or matures but does not multiply – filarial worms – river blindness and black flies iii. PROPAGATIVE TRANSMISSION No cyclical change but organism just multiplies E. g. Plague (Bacteria), Viruses, e. g. Yellow fever and mosquito Role of Obligate Vectors Vector is an essential element in the Pathogen’s life cycle to complete its development before being transferred to another organism. These infectious agent travel mainly through the Hemolymph The vector rarely gets ill as the pathogen needs them to complete it’s life cycle and may modify the hosts mouthparts Infectious agents need carriers to help them spread, Vectors Vectors are able to adapt to various ecosystems due to their enormous resilience in view of control activities and management. Vectors greatly increase the dispersal and transportation range of infectious agents. Vectors act as a bridge between different species of animals and humans, without vectors, many illnesses would remain affecting specific organisms instead of spreading through different species, Vectors. Vectors act as reservoirs of pathogens and enable them to survive during unfavourable periods. Relationship between pathogen and vector tends to last to the end of the vectors life Climate change, global transportation, changes in agricultural practices and commercial exchange is an open door for international transportation of vectors. Impact; According to WHO there are 1000 million cases of vector- borne diseases and more than > 1 millions deaths a year.  3. INTERMEDIATE HOSTS An intermediate host is the organism that hosts a pathogen during part of its life cycle but not to the point of reaching sexual maturity. Pathogens may persist in the intermediate host for a long time.  INSECT-MAN CONTACT The greatest problems are apparent in tropical areas where higher temperature are unrelieved by extreme winter allow vector populations to reproduce more quickly and often permit all year transmission Many members of insects/arachnids live in close association with humans and readily attack and feed on man They are thus important and because of their physical attack and blood sucking habits – HAEMATOPHAGOUS The INSECT-MAN CONTACT is also an important factor in determining the spread of an ORGANISM (the PATHOGEN). Example: Do these insects live on man as a true parasite or in his clothes and bedding or within body tissues or on their pets and occasionally bite them?  INSECT-MAN CONTACT In tropics people; 1. wear fewer clothes 2. Live in close association with animals but do not groom them enough 3. Have poor housing construction Bright coloured clothes, cosmetics and soaps attract some insects When an insect bites MAN whether there is either an infection or not there is of necessity a wound, pain and irritation  INSECT-MAN CONTACT Histological changes may occur at the site and immunological reaction play an important role in the type of reaction. Dominant symptoms may be as a result of the pharmacological action of chemicals in the arthropods saliva or venom As a CLINICIAN/MEDICAL PERSON, you should be able to identify common INSECT species and a have a VAGUE idea of life cycle Breeding sites and General habits of the creature causing the skin reaction.  INSECT-MAN CONTACT You will then know 1. The most suitable treatment 2. What advice to give the patient 3. What to do in an emergency ANAPHYLAXIS – ANAPHYLACTIC SHOCK ASTHMA Acute reaction to a foreign protein / antigens etc etc  CONCLUSION By the end of this course which is of great public health importance, you should be able to; 1. Identify vectors and diseases that are common in your community 2. Confirm the groups of arthropods to which most pests and vectors belong 3. Know the necessary vector control measures and strategies for disease control.  SUCCESSES Initial programmes have been successful eg OCP Often short lived as vectors develop resistance easily creating the need for new more expensive chemicals Suspension of control programmes eventually leads to a significant increase in the level of disease transmission Permanent success occurs mostly where environment is changed to prevent vector from breeding Forensic Science: Forensic entomology helps to determine the time of death, e.g. blood flies, blue bottle flies soon invade a corpse after its exposure. Maggot therapy