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