Biology 201 Introduction and Tropical Parasites I

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Biology 201Introduction and Tropical Parasites I
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Comprehensive Final Concepts

• Infectious Diseases
• Cause HALF worldwide deaths - 25 million/year
• 5-10 developed nations 60-70 developing
• Caused by biological agents, usually
• Microbial Pathogens viruses, bacteria, parasites
• Many transmitted by vectors - e.g. insects
• Contrast non-infectious genetic, environmental

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• Top 15 Infectious Diseases
• 12-15 Tropical Parasites - 0.13 million/year
• 11 Hepatitis B - 0.10 million/year
• 10 Syphilis - 0.16 million/year
• 9 Meningitis - 0.17 million/year
• 8 Tetanus - 0.21 million/year
• 7 Pertussis - 0.30 million/year
• 6 Measles - 0.60 million/year
• Effective vaccines given in developed nations.

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• Top 15 Infectious Diseases Continued
• 5 Malaria - 1.3 million/year
• 4 Tuberculosis/TB - 1.6 million/year
• 3 GI/Diarrheal Diseases - 1.8 million/year
• 2 HIV/AIDS - 2.8 million/year
• 1 Pneumonia/Influenza - 3.9 million/year
• Some Emerging - New (e.g. SARS Pneumonia) Some
  Re-Emerging - Old Problems (e.g. TB)

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• Class Organized by Group - Big to Small
• Unit 1 Parasites/Protozoa - Eukaryotic Cells
• Unit 2 Bacteria - Prokaryotic Cells
• Unit 3 Viruses - not cells, not living
• Unit 4 GI, Respiratory - many agents above
• For each, there are 1-2 homework/discussion
  activities and 1 exam with case-study essays.

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Unit One Start - Introduction to Biology

• Concept One What Is Living?
• Organization - made of cells, DNA information
• Growth, development, reproduction
• Evolution and adaptation - respond, regulate
• Metabolizes and processes energy
• Cells either eukaryotic (unit one) or prokaryotic
  (unit two) - compare/contrast for final!

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• Eukaryotic Cells
• Cell membrane - fats/lipids, some proteins
• Cytoplasm - between nucleus, cell membrane
• Nucleus - command center, DNA information
• Major Organelles - mitochondria, chloroplast
• Motility Proteins - flagella, cytoplasmic
  filaments
• Hard Outer Wall (some) - e.g. cellulose, chitin
• Think about - strong evidence that organelles
  engulfed/enslaved prokaryotes

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• Concept Two Hierarchy of Biology
• Molecules carbohydrate, fat, protein, DNA/RNA
• Cells prokaryotes vs. eukaryotes
• Multicellular Organization tissues, organs
• Ecology interactions - organisms, environment

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• Concept Three Classification
• Domain, Kingdom - know for all agents
• Phylum, Class, Order, Family - know if given
• Genus species - know for all agents if given
• Strains - sometimes used, differ by 1-5 genes
• Challenge problem for next time classify
  yourself using appropriate terms above.

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• Domain - New Term Since 1980s
• 3 Domains - uses DNA sequence data, genetics
• Generally reflects cell structure, appearance
• Eukaryotes - animals, plants, fungi, protozoa
• Bacteria - prokaryote, moderate, 3 pathogens
• Archaea - prokaryote, extreme, no pathogens
• Traditional Kingdoms animals, plants, fungi,
  protozoa, and monera (bacteria archaea).

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Introduction to Animal KingdomHome of the
parasites - Unit One

• Some Key, Relevant Features
• Multicellular eukaryotes - so which domain?
• Many show distinct tissue and organ structure
• Metabolism use chemicals for energy
• Most reproduce sexually, some asexual/clone
• About 16 phyla - only 1 includes vertebrates

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• Phylum Nematoda - a.k.a. Roundworms
• From the Greek nematos thread ode like
• 20,000 known species, 15,000 parasitic
• Diverse aquatic and soil habitats
• Important biological control agents. Others will
  be described during GI diseases lectures.

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• Anatomy and Physiology
• Pseudocoelom/simple body cavity, no segments
• GI simple mouth to gut tube
• MS outer cuticle, hydrostatic, simple muscles
• BG no vessels, simple diffusion
• SL cilia hairs, simple nerves, no central
  control
• GI (gastrointestinal), MS (muscle/skeletal), BG
  (blood/gas), SL (sensory, locomotion).

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• Reproduction and Development
• Reproduction sexual, dimorphic
• In host female worms birth 1000 embryo/day
• Embryos to larvae that move through blood
• Taken up by insect vectors, new larvae forms
• Mature in new host - location varies with disease

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• Lymphatic Filariasis
• First agent mosquito-linked - Bancroft, 1876
• Mostly in tropical Anopheles mosquitoes
• Human Tissues - lymphatic system, blockage
• Larvae in pulmonary vessels most of day,
  peripheral most of night - significance?

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• Crash Course - Immune/Lymphatic System
• Animals have varying levels of defense systems
• Lymphatic system - vessels parallel blood
• At capillaries, lymph drains to lymphatic system
• Lymph - defensive white cells, proteins (e.g. Ab)
• Nodes/spleen - data processing, dump junctions
• More during HIV swollen nodes infection.

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• Lymphatic Filariasis - Disease
• High volume of molting larvae, dying adults
• Acute lymph destruction/blockage, inflammation
• Elephantiasis - constant untreated, skin necrosis
• Wuchereria bancrofti - extremities, genitals
• Brugia malayi - extremities, not genitals
• Even without elephantiasis, filariasis usurps and
  destroys immune system - significance?

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• Lymphatic Filariasis - Epidemiology
• 120 million affected worldwide - total, current
• 75 Asia/Pacific 25 Latin America, Africa
• Last endemic US cases - S. Carolina, 1920s
• 15,000 US Servicemen contracted, WWII
• 7 Haitian refugees to US infected
• Typically, short-term tourists dont contract
  requires long-term exposure.

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• Onchocerciasis/Loa Loa Eyeworms
• Major causes of blindness, carried by
• Tropical fast-water Simulium flies (Onchocerca)
• Tropical Chrysops deer flies (Loa Loa)
• Tissues affected - subcuteneous skin, 5 eye
• Highly prolific - 15 years, 2000 embryos/day

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• Eyeworm - Disease
• From bite, larvae migrate through blood/lymph
• 5 cases result in blindness - agent in eyeball
• Where worms mature, defenses make capsules
• Tissue thickens/keratitis, loses pigment, itches
• Even without blindness, can infect lymph nodes
  and cause elephantiasis-like symptoms.

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• Eyeworm - Epidemiology
• 20 million affected worldwide - total, current
• Majority - Africa Nigeria, Sudan, Congo region
• Others - Middle East, Latin America, Asia
• Slave trade introduced to Americas 1500-1800
• Napoleon - Sudanese troops in Mexico, 1862
• Onchocerca (worldwide), L. loa (West Africa)
• 85 West African eye lesions, with 50 adult
  males blind Typically, tourists dont contract.

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• Anti-Nematode Treatment - Avermectin Drugs
• Similar in structure to GABA - neurotransmitter
• Vertebrates - GABA only brain because of BBB
• Nematodes lack CNS but use GABA as a
• Neuromuscular transmitter throughout body
• If we take orally, BBB keeps out of brain - so?
• Older drugs (DEC/diethylcarbamazine) similar
  effect but less specific (i.e. more side effects).

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