2MICRO1-MB444 Parasitology & Related Concepts PDF

2MICRO1 TRANSES - MB444: PROTOZOOLOGY & PARASITOLOGY LECTURE FIRST SEMESTER / ACADEMIC YEAR 2024-2025 PROF. KENNETH SANCHEZ TOPIC 1.1: INTRODUCTION TO PARASITOLOGY AND RELATED CONCEPTS WHAT IS SY...

2MICRO1 TRANSES - MB444: PROTOZOOLOGY & PARASITOLOGY LECTURE FIRST SEMESTER / ACADEMIC YEAR 2024-2025 PROF. KENNETH SANCHEZ TOPIC 1.1: INTRODUCTION TO PARASITOLOGY AND RELATED CONCEPTS WHAT IS SYMBIOSIS? COMMENSALISM Symbiosis (sim’bī-ōs’ɘs, sim’bē-ōs’ɘs) (Gr. syn, with, + ➔ A relationship in which one individual lives to bios, life). The living together of two different species in close or on another and benefits, and the host an intimate relationship. is unaffected; often symbiotic. ➔ At least one species benefits; the other species may benefit, maybe unaffected or maybe harmed (mutualism, commensalism, and parasitism, respectively). Note: Symbiosis is an interaction between two or more organisms MUTUALISM Example: About three-quarters of all orchid species are ➔ A type of interaction in which two different epiphytes. Epiphytes are plants that live and grow on species derive benefit from their association, other plants. Orchids growing on trees have a special which may be necessary to both; often kind of symbiotic relationship with their hosts. symbiotic. OTHER EXAMPLES ➔ Win-win situation 1. Livestock and cattle Egrets 2. Sharks and Remora fish 3. Whales and barnacles PARASITISM ➔ The condition of an organism living in or on another organism (host) at whose expense the Example: Protozoa oozing through the gut of a termite. parasite is maintained; destructive symbiosis. These organisms help the termite digest cellulose in the wood it eats in what is considered one of nature’s classic example of symbiosis. OTHER EXAMPLE 1. The clownfish and sea anemones ➔ clownfish live among the tentacles of sea anemones, which protect them from predators. At the same time, the Example: Parasitoidnwasp inject their eggs into other fish help the anemones keep clean, and arthropods caterpillars, using a stinger-like probe. provide them with nutrients through their waste. MB444: PROTOZOOLOGY AND PARASITOLOGY | 2MICRO1 | AGUIRRE & HIDALGO 1  2MICRO1 TRANSES - MB444: PROTOZOOLOGY & PARASITOLOGY LECTURE FIRST SEMESTER / ACADEMIC YEAR 2024-2025 PROF. KENNETH SANCHEZ TO IDENTIFY PARASITES Victim Parasitoid/Parasitic Typical predator ➔ They must be taking away the nutrients (blood, fitness = 0 castrators - A natural enemy oxygen, etc.) of the host. - A natural enemy attacks more than attacks one victim one victim during a during a life stage life stage and PREDATOR vs PARASITE vs PARASITOID and necessarily necessarily eliminates its fitness eliminates its fitness. Parasitoid - They tend to be are insects, typically bigger than their wasps or flies (orders prey. Hymenoptera and Diptera, respectively), whose immature stages feed on their host’s body, usually another insect, but finally kill the host. Parasitoids resemble predators in this Victim fitness = 0 indicates that the interaction either regard, but they only kills or blocks victim reproduction, whereas victim require a single host fitness >1 indicates that the victim typically survives the individual. interaction and can reproduce. Parasitic Castrators (e.g. digene rediae Attacks one victim Attacks more than and sporocysts, per life stage one victim per life Schistocephalus (Parasite) stage (Predator) tapeworm plerocercoids or Victim Typical Micropredator Rhizocephala) usurp fitness > 0 parasite/pathogen - A natural enemy the reproductive - A natural enemy attacks more than efforts of the host but attacks one victim one victim during a do not kill it. during a life stage life stage and does and does not not necessarily necessarily eliminate eliminate its fitness EXAMPLES: its fitness (They don’t (e.g. mosquito, Typical Predator: Leopard seal usually kill their host). leeches, lamprey, leaf hopper). These Prey: Penguin (Victim’s fitness = 0) take a small meal before moving on. - They are smaller than their prey MB444: PROTOZOOLOGY AND PARASITOLOGY | 2MICRO1 | AGUIRRE & HIDALGO 2  2MICRO1 TRANSES - MB444: PROTOZOOLOGY & PARASITOLOGY LECTURE FIRST SEMESTER / ACADEMIC YEAR 2024-2025 PROF. KENNETH SANCHEZ ➔ Hidden head lice of the western ground parrot. Predation - An interaction where one organism (predator) eats another organism (prey). ➔ It is one of the common feeding behaviours that includes parasitism and micropredation (which usually do not kill the host) and parasitoidism (which always does, eventually). Scavenging - prey is already dead ➔ Example: hyenas (they only eat hunted down prey) ➔ Opportunistic scavenging- they will scavenge for food whenever the ➔ Parasitoid fly reproducing in male cicadas. opportunity arises (Inaagaw yung dead prey) Predation and herbivory overlap because seed predators and destructive frugivores kill their “prey”. ➔ Herbivory - Passively browsing (parts of plants eaten) ➔ Grazing - actively looking for food/grass/plant WHAT IS PHORESIS? ➔ Phoresis: form of symbiosis when the symbiont, the phoront, is mechanically carried about by THE RELATIONSHIP OF PREDATION TO OTHER FEEDING its host. STRATEGIES ➔ Neither is physiologically dependent on the other. ➔ It is a non-permanent, commensalistic interaction in which one organisms (a phoront MB444: PROTOZOOLOGY AND PARASITOLOGY | 2MICRO1 | AGUIRRE & HIDALGO 3  2MICRO1 TRANSES - MB444: PROTOZOOLOGY & PARASITOLOGY LECTURE FIRST SEMESTER / ACADEMIC YEAR 2024-2025 PROF. KENNETH SANCHEZ or phoretic) attaches itself to another (the host) temple, in return for certain services. These solely for the purpose of travel. services included collecting and keeping the ➔ It is a one-sided relationship since the phoront supplies of corn due to the temple, helping at is the only one who benefits and the host does certain sacrifices, and preparing the banquets not get any at all. connected with certain festivals. Example: ADAPTATION OF PARASITISM Epibionts attached at different body parts of Morphology includes: zooplankton from Sorsogon. Various penetration glands Cysts Hooks and suckers for adhesion Increased grwoth and reproductive capacity Sense organs are poorly developed GLANDS Dorsal view of the Schistosoma mansoni cercaria observed under the light microscope after fixation in silver nitrate (~330um long). It is a swimming larva thanks to its bufircated tail. The oral sucker and the ventral First records of Epistylis and Zoothamnium as epibionts sucker (known as acetabulum) of freshwater copepods in the Philippines facilitate attachment to the tegu,aent of the definitive host. THE FIRST PARASITE Pre- and postacetabular glands facilitate host penetration thanks to their proteases. The tail is shed upon penetration. ➔ Para (beside, by) — sitos (wheat, grain, food) — 1. ESCAPE GLANDS: contents are expelled during logia (study) the emergence of the cercaria from the snail. ➔ The term parasite, dated as early as 1539 (first 2. HEAD GLANDS: for post penetration adjustment evidence, MW), originally meant “a person who 3. POSTACETABULAR GLANDS: produce mucus; exploits the hospitality of the rich and earns help cercariae adhere to surfaces welcome by flattery” 4. PREACETABULAR GLANDS: secretion contains ➔ Denoted originally among the Greeks the calcium and enzymes (e.g. protease); host skin priest’s assistant, who (like the priest) received penetration his support from the offerings made to the MB444: PROTOZOOLOGY AND PARASITOLOGY | 2MICRO1 | AGUIRRE & HIDALGO 4  2MICRO1 TRANSES - MB444: PROTOZOOLOGY & PARASITOLOGY LECTURE FIRST SEMESTER / ACADEMIC YEAR 2024-2025 PROF. KENNETH SANCHEZ CYSTS ➔ A cyst is resistant, quiescent stage of an organism, usually with a secreted wall. ➔ In zoonoses and medical diseases, cysts are the infectious form of the parasite and are usually found in the normal stool of asymptomatic carriers or humans with mild disease. ➔ Cysts can be incidentally discovered by radiography. Specific antibodies are detected by different serological tests and cansupport the diagnosis. HOOKS AND SUCKERS Example: Cysticercosis can be diagnosed by the ➔ Hooks are short, curved, hardened structures demonstration of larval Taenia solium cysts that protrude from the surface of a parasite. (cysticerci) in tissue sections. ➔ An example of a parasite with hooks belong to hookworms species. ➔ Attachment of the hookworms of the hookworms to the intestinal wall may stimulate abdominal pain, nausea, and anorexia. Cysticercosis. Frontal Xray of the pelvis of a 30-year old female patient with Cysticercosis, showing calcified cysts (small white dots) throughout the thighs and hip region. MB444: PROTOZOOLOGY AND PARASITOLOGY | 2MICRO1 | AGUIRRE & HIDALGO 5  2MICRO1 TRANSES - MB444: PROTOZOOLOGY & PARASITOLOGY LECTURE FIRST SEMESTER / ACADEMIC YEAR 2024-2025 PROF. KENNETH SANCHEZ Left: Large and small rostel-lar hooks of Taenia Live on the outer surface of the host; external multiceps. Above: Freshwater leech’s rear sucker. Colored SEM of PERMANENT the rear sucker of a freshwater leech (family Parasites live their entire adult lives within or on their Hirudinidae) hosts. INCREASED GROWTH AND REPRODUCTIVE CAPACITY Made them very successful in surviving for millions of years. ➔ Metamerism is the characteristic of nematozoans, which create repeated body segments. Segmentation of the body ➔ Proglottids contain a complete reproductive organ of males and females. TEMPORARY/INTERMITTENT A parasite that feeds on the host and then leaves. - often referred to as Micropredators, in recognition of the fact that they usually “prey” on several different hosts (or the same host at several discrete times) TYPES OF PARASITES PARASITOIDS ENDOPARASITES Live within the host; internal Obligate parasites - cannot complete their lifecycle without spending at least a part of their time in a parasitic relationship. Facultative parasites - not normally parasitic but can become so when they are accidentally eaten or enter a wound or body orifice (Example: amoeba) Accidental (=incidental) parasites Insects (e.g. wasps or flies) whose immature stages feed on their host’s body (usually another insect), and ECTOPARASITES finally kills the host MB444: PROTOZOOLOGY AND PARASITOLOGY | 2MICRO1 | AGUIRRE & HIDALGO 6  2MICRO1 TRANSES - MB444: PROTOZOOLOGY & PARASITOLOGY LECTURE FIRST SEMESTER / ACADEMIC YEAR 2024-2025 PROF. KENNETH SANCHEZ HOST PARASITOIDS ➔ The host plays a role in the life cycle of the parasite ➔ Invertabrates and vertabrates ➔ It acts as the environment for the parasites TYPES OF HOST DEFINITIVE HOST (DH) In which the parasite reaches sexual maturity Amoeba and Trypanosomes - Arbitrarily Only the immature stages are parasitic (some insects, assigned humans as DH. mermithid nematodes, and hariworms), adults are free-living. INTERMEDIATE HOST (IH) HYPERPARASITES A host that is required for parasite development; however, the parasite does not reach sexual maturity. PARATENIC HOST OR TRANSPORT HOST The parasite does not undergo any development but remains alive and infective to another hosy RESERVOIR HOST Any animals that harbors an infection that can be transmitted to humans Hyperparasite: Adult tapeworm Example: Parasite: Flea Host: Dog ➔ A hyperparasite is an organism which establishes a parasitic interaction with a parasite. ➔ Many parasites host other parasites, a condition known as hyperparasitism. Examples are Plasmodium spp. in mosquitoes, a tapeworm juvenile in a flea, a monogene (Udonella caligorum) on a copepod parasite of fish, and the many insects MB444: PROTOZOOLOGY AND PARASITOLOGY | 2MICRO1 | AGUIRRE & HIDALGO 7  2MICRO1 TRANSES - MB444: PROTOZOOLOGY & PARASITOLOGY LECTURE FIRST SEMESTER / ACADEMIC YEAR 2024-2025 PROF. KENNETH SANCHEZ VECTORS VS. INTERMEDIATE HOSTS HOST SPECIFICITY ➔ Vectors are vehicles by which infections are ➔ Most parasites develop only in a restricted transmitted from one host to another. range of host species. EXAMPLES: ➔ Usually, a product of host-parasite co-evolution ➔ Absolute host specificity: scenario where a parasite sexually mature only in a definitive host Example: Ixodes woyliei (tick) in woylie (marsupial) TRANSMISSION AND LIFE CYCLES ZOONOSIS Transmission to humans of parasites normally found in wild and domestic animals E.g. Trichinella, Trichinosis Humans become infective when they enter the life cycle (eating undercooked meat). DOMESTIC CYCLE ➔ Also known as Urban Cycle ➔ Cycle between vectors and humas ➔ Cycle between vectors and non-wild, urban, or domestic animals. INFECTIONS AT THE ECOTONE Some of the most medically important vectors are anopheline mosquitoes, which transmit malarial parasites, and snails of certain genera, which carry infective larval blood flukes, or schistosomes. MB444: PROTOZOOLOGY AND PARASITOLOGY | 2MICRO1 | AGUIRRE & HIDALGO 8  2MICRO1 TRANSES - MB444: PROTOZOOLOGY & PARASITOLOGY LECTURE FIRST SEMESTER / ACADEMIC YEAR 2024-2025 PROF. KENNETH SANCHEZ PRISTINE FOREST This map shows an approxiamation of the parts of the Penetration by illegal loggers and hunters lead world where malaria transmission occurs. to habitat degradation, the reduction of large EDIA fauna and the proliferation of rodent, bat, bird, and primate species which can act as disease reservoirs. ECOTONE Human activities, especially livestock farming and feedstock cultivation, cause deforestation and bring wild animals in contact with humans and domestic animals Sylvatic pathogens are no longer controlled by TE HOSTS environmental stochasticity. URBAN/PERI-URBAN As wild habitats are degraded, wild animals enter urban areas in search of food Crowding and food deprivation may increase wildlife susceptibility to pathogen infection and shedding TRANSMISSION AND LIFE CYCLES HEALTH IMPACT MB444: PROTOZOOLOGY AND PARASITOLOGY | 2MICRO1 | AGUIRRE & HIDALGO 9