Parasitology
Why do we study parasites? Give four examples
1. Biological phenomena- Adds to overall understanding 2. Medical importance- causative agent for health problems 3. Veterinary importance- Cross species transmission 4. Economic importance- human productivity and agricultural pursuits
What are the five categories of symbiosis and in your own words give a short and brief description of it with a example.
1. Commensalism- same table. spatial not physiological interaction. Ex. Sea anemones and hermit crab 2. Phoresis- to carry; spatial relationship not physiological. Ex. beetle with mites on back 3. Mutualism- both species benefit Ex. clownfish and sea anemon and termites and flagellates 4. Parasitism-One benefits one is harm; derives nutrients from host. Ex. tape worm 5. Competition
Name 3 tropical diseases, know what they are, and what causes it
1. Malaria- Disease caused by parasitic protozoans that are transmitted through vectors (mosquitoes). 2. African trypanosomiasis- vector-borne parasitic disease caused by Trypanosoma brucei and transmitted through tsetse fly 3. Filariasis- Parasitic infection caused by an infection with roundworms that affect lymph nodes. Transmitted through infected mosquitoes
Four stages of portal
1. Mode of entry 2. Site of election in the body 3. Mode of exit 4. Survive in the environment
Four subgroups of protozoa
1. Sarcodina (amoebas) 2. Sporozoa (sporozoans) 3. Mastigophora (flagellates) 4. Ciliata (ciliates)
The three hypothesis which offer explanation for virulence in pathogensMas
1. The trade-off hypothesis- balance betwwen cost and benefit 2. Short-sighted evolution- reproduction base 3. Coincidental evolution-accidental by product of selection
7 factors influencing prevalence of a disease
1. Unsanitary living conditions- gutters 2. Inadequate fundings for disease control 3. Poor nutrition- protein deficiency 4. Lack of health education 5. Cultural/religious customs- ablution 6. Climatic conditions- subtropical, exposed skin, water 7. Compromised immune system- HIV
Parasites mode of entry
1. ingestion, arthropod bites, and peneyration of skin
Anthropogenic
Actions caused by humans that affect environment and that changes physiology of parasites which then affects hosts
Symbiosis
Two or more phylogenetically organisms that differ genetically living together
Epidemic
Unusual occurrence of a disease. Quickly spreading Ex. Influenza
Factors that make it hard to control parasitic infections?
Vectors- breeding sites, strains resistant to pesticide, contaminated water Intermediate hosts- aquatic conditions and specialized intermediate hosts that protect themselves Diagnosis- misdaignosis. Difficult to determine Resistance and resurgence- resistance to drug and overcrowding
Human filiaris
Caused by filarial worm and can be transmitted to humans from cats or monkey reservoirs
Endemic
Constant presence of a disease within a population (local)
Hairworm Life cycle
Cricket drinks contaminated water. Larvae feeds on crickets tissue and grows into adult until it fills cricket's body cavity. Cricket jumps into water and drowns, hairworm exits cricket and mates and life cycle begins again
The arrival of previously unknown zoonotic diseases may arise from what?
Ecological and climate changes with mode of vector
Infestation
Ectoparasites
Explain Visceral Larval Migrans cycle in your own words
Eggs develop into embryonated egg in environment. Ingestion by either adult dog or child. Eggs hatch in gut and larvae is released and penetrates gut. Larvae enters circulation and migrates to visceral organs where development is arrested (In pregnant and lactating dogs the larvae can be reactivated and cause intestinal infection i in mother and infection of offspring). Larvae is released in intestine and in case of heavy infection larvae can be passed in feces. In puppies after ingestion larvae is released in intestine and if heavy infection larvae can be released in feces. If not travels through circulation. Then become adults in lumen of intestine then eggs are passed in feces.
Infection
Endoparasites
Toxoplasma gondii
Enslaver parasite that infects host (rat) and rat is attracted to cat. This is to ensure transfer to new host (cat) in its complex life cycle
Vertical transmission
Family
Tapeworm Life cycle
Flea larvae eats eggs. Flea matures. Pets eat flea. Parasite larvae migrates to intestine where they mature. Proglottids containing eggs are released in feces. And the cycle repeats itself
Common pathway for transmission for transmission of parasite
Food or water, vectors, flea, sexual contact, inhalation, or skin penetration
Factors that facilitate spread of disease
Genetic change, adaptation, and change in human behavior and inhabitant
Give an example of way enslaver parasites appear to manipulate host biochemistry
Hairworm alters 3 amino acids in brains of cricket host. The chemical taurine is an important neurotransmitter in insects that regulate thirst.
Carriers
Harboring diseases with lack of symptoms that could be spread through discharge or excretions. Incubation period- measles, convalescence period-typhoid fever, prolonged period- typhoid fever
Nosocomial infection
Hospital acquired infection. Ex. is Hepatitis B. Most caused by protozoa
Epidemiology Triad
Host- demographic, biological, and socioeconomics Agent- biological, physical, chemical, mechanical agents Environment- physical, biological, and social environment
Types of reservoir
Human, animal, and inanimate reservoirs
Definitive host
If parasite maintains sexual maturity and in adult form
Biological vector
In which parasite develops and essential in life cycle
Types of Parasites
Incidental (accidental)- appears unusual host Ex. heartworm Erratic-Seen in unusual locations in host ex. heartworm in eye Obligate- must lead host existence- no free living stage. Ex. mites Facultative- Free living organism that can become parasitic. ex. ringworm in cats psuedoparasite- Organism that appear to be parasites but not. ex. pollen grain
Incubation vs Latent
Incubation: Time for exposure to time of death Latent-Period between the exposure and the onset of infection
Reservoir host
Infected animals that serve as sources of infective organism for humans. Wild animals- sylvatic and domestic-domestic
Accidental host
Infection of human or animal with parasite not commonly found in that host
Types of Host
Intermediate-immature parasite undergoes non-sexual development in host. ex. heartworm larva in mosquito Paratenic- Serves as transport host for parasitic larva. ex. fleas, mice, etc. Definitive- Harbors sexually mature parasite. Final host. ex. carnivores Incidental- wrong host for species. ex. heartworms in cats
Sandfly that carries protozoan: Name of parasite, intermediate host/vector, name of disease, and breeding site
Leishmania braziliensis, Sandfly, and mucocutaneous leishmaniasis, and low light and high humidity
Direct life cycle (monoxenous) vs indirect life cycle (complex)
Monoxenous- Not as virulent, entire life cycle within one host, and direct life cycle Heteroxenous- Virulent, one or more intermediate host, and indirect life cycle
Soil transmitted helminths
Most common infection is poor areas with bad sanitation and transmitted by eggs in human feces that contaminate soil. Ex. roundworm, hookworm, and whipworm
3 types of phagocytic cell
Neutrophils (engulf), Macrophages (all over body), Dendrites (activate adaptive)
Incidence of infectious disease
New cases in a given time period
Horizontal transmission
Non-relative
Accidental host
Not suitable for parasite development but can still cause disease
Morbidity rate
Number of individuals infected at a given period per population
Mortality
Number of people who have died from a disease at a given time
Obligatory vs facultative parasites
Obligatory parasites are dependent on host to survive while facultative can live with or without the host
Sporadic disease
Occur irregularly from time to time but can be epidemic
Human bancroftian parasite, vector, and breed site
Parasite is bacrofti, vector is mosquitoes, and poor sanitation
Passive vs Active vs Inoculative transmission
Passive- does not travel to host. Usually ingested. ex. roundworms Active- parasite travels to host. ex. fleas Inoculative- vectors. ex. mosquitoes
Case
Person in group or population with a particular disease
HIV related bacterial infections
Pneumonia, respiratory infection, and TB
Reproductive rate of infection
Potential for infectious disease to spread
Reproductive rate of infection and influential factors
Potential for infectious disease to spread. Influential factors are probability of transmission, frequency of pop. contact, duration of infection, virulence, pop. immune proportion.
Two major group of parasites
Protozoa (unicellular)- single celled, heterotrophically, diverse mobility Metazoa/helminths (multicellular)- body composed of cells
What are the three major groups of parasites
Protozoa- Amoebas, flagellates Helminths- worms such as tapeworm and round worm Arthropods- ectoparasites or vectors such as ticks, mites, and mosquitoes
Mast cell
Releases histimine
Parasitic infections tend to be concentrated within
Small geographical areas, families, and short distance between area suffering from infection
Typical characteristics of parasites
Smaller than host, more than host, evolve to invade host immune, can change host behavior, high reproduction rate, unique morphology, usually non-lethal, and specificity
Epidemiology
Study of distribution and determinants of health related states and events in population, and application of this study to control health problems.
Opportunist infection
Takes advantage of host weak immune system
Amount of time on host
Temporary- Visits for food. Ticks, mosquitoes, etc. Stationary- Spend definite amount of time in or on host. Most parasites Permanent- Spends entire life on host except when transferring. Ex. is lice
Most common opportunist infections in HIV infected patients
Toxoplasmosis- parasite is toxoplasma gondii, carried by cats, and can get by inhaling contaminated dust, and undercook food. Prevention is cat care, hand hygiene, and properly cook food. Cryptosporidiosis- caused by cryptosporidium hominis, spreads through contaminated food, and causes diarrhea Cystoisosporiasis- caused by cystoisospora belli, spread by contaminated food/water, and causes diarrhea.
Acquired immunity
humoral (antibodies eliminate toxins in blood) and cell mediated (specialized T cells destroy infected host cell)
clonal selection
proliferation of lymphocytes
How do we measure host parasitic virulence?
reduce host survival and reproduction
Intermediate host
temporary but essential for life cycle of parasite. Never fully matures. Ex. plasmodium vivax where intermediate host is humans where larvae forms but mosquito is where parasite undergoes sexual reprosuction
Transfer/paratenic host
temporary refuge for reaching definitive host in cell
Mechanical vector
transfer by medical means and may and not essential for life cycle
Helper T cell
triggers humoral and acquired reponses
Two types of epidemic
-Common source epidemic- arises from contact with contaminated source such as water with fecal matter or food poisoning. -Propagated epidemic- person to person contact. ex. common cold. Harder to deal with
Vector
Animate or inanimate way to transfer infectious organism
T-cell
Antigen presentation/MHC
HIV related parasitic infections
Toxoplasmosis, Giardiasis, Isosporiasis, and Cryptosporidiosis
B-cell binding antigen produce
antibody (Ig)
Adaptive immune system characteristics
diversity, self tolerance, B & T cells, memory
two types of clone produced
effector cells (short term) and memory cells (long live)
Prevalence of an infectious disease
number of cases at a given time
Incidence of a disease is the
number of new cases in a set population over a specific period