PARASITOLOGY WEEK 1 ZEIBIG PDF

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for its survival and usually at the expense of the host.

Parasitology 

The area of biology concerned with the phenomenon of dependence of one living organism on another

Medical parasitology 

Is concerned primarily with animal parasites of humans and their medical significance, as well as their importance in human communities

Tropical medicine 

Is a branch of medicine which deals with tropical diseases and other special medical problems of tropical regions.

Endoparasite 

Ectoparasite 

Is an illness, which is indigenous to or endemic in a tropical area but may also occur in sporadic or epidemic proportions in areas that are not tropical

Symbiosis 

Is the living together of unlike organism

Commensalism 

Is a symbiotic relationship in which two species live together and one species benefits from the relationship without harming or benefiting the other



is a symbiosis in which two organism mutually benefit from each other.

Parasitism 

is a symbiotic relation where one organism, the parasite lives in or on another. Depending on the latter

presence of endoparasite in a host

Infestation 

presence of an ectoparasite on a host

Obligate parasite 

they need a host to complete their development and propagate their species

Facultative parasite 

parasite may exist in a free-living state or may become when need arises

Accidental or incidental parasites 

parasite which establishes itself in host where it does not normally live

permanent parasite 

remains in the body of the host its entire life

temporary parasite 

Mutualism 

living outside the body

Infection

Tropical disease 

living inside the body

parasites lives on the host only for a short period of time

spurious parasite 

is a free living organism that passes through the digestive tract without infesting the host

ROUTES OF INFECTION AND TRANSMISSION In order to survive, the parasites must have some means of locating and

invading new hosts (invasion and infection). After the development and maturation withing the host the next generation must be able to escape (transmission) from the host



Paratenic host 

Oral 

Eggs or infectious larvae swallowed via food or accidentally

Penetration 

By specialized larvae that, once they make contact with the host, can pierce through the skin or outer covering of the host

harbors the asexual or larval stage of the parasite

is one which the parasite does not develop further to later stages. However, parasite remains alive and is able to infect another susceptible host

Reservoir host 

they allow the parasite’s life cycle to continue and become additional sources of human infection

VECTORS Biological vectors 

Via a vector 

Usually, an arthropod that feeds upon the body fluids of a vertebrae transmits an infectious state of the parasite

transmits the parasite only after the latter has completed its development within the host

Mechanical or phoretic vector 

transports only the parasite

Contact 

Infectious stages penetrate a host during copulation

ROUTES OF INFECTION (INVASION) The most common method of escape of eggs or larvae is via the feces or urine. However, escape can occur through any of the orifices. Via vector, while feeding an arthropod could also passively consume a stage of the parasite. Th e parasite may actively breakthrough the skin to escape.

EXPOSURE AND INFECTION Majority of animal parasites are pathogens which are harmful and frequently cause mechanical injury to hosts Carrier 

Exposure 

HOST Definitive host 

is one which parasite attains sexual maturity

Intermediate host

Harbors particular pathogen without manifesting any signs and symptoms

Is the process of inoculating an infective agent, while infection connotes the establishment of the infective agent in host

Incubation period 

In the period between infection and evidence of symptoms

Pre patent period 

Also known as the biologic incubation period, is the period between infection or acquisition of the parasite and evidence or demonstration of infection

Autoinfection 

Results when an infected individual source of infection

Superinfection or hyper infection 

Happens when the already infected individuals are further infected with the same specie leading to massive infection with the parasite

Sources of infection are: contaminated soil and water, lack of sanitary toilets, food, arthropods transmit infection, person (beddings, and clothing, the immediate environment) Modes of transmission: mouth, skin penetration, congenital transmission, inhalation of air-borne eggs, sexual intercourse. Ingestion of contaminated food:   

Taenia solium- pork tapeworm Taenia saginata- beef tapeworm Diphyllobothrium latum- fish tapeworm

Drinking contaminated water:  

Entamoeba histolytica Giardia lamblia

Improperly cooked fish:   

Clonorchis Opistorchis Haplorchis

Skin penetration:

  

Hookworms Strongyloides (via soil) Schistosomes (via water)

Insect vectors:    

Malaria Filariasis Leishmaniasis Trypanosomiasis

Congenital transmission: 

Toxoplasma

Mother’s milk/transmammary:  

Ancylostoma Strongyloides

Airborne: 

Enterobius

Sexual intercourse: 

Trichomonas vaginalis

PARASITE EFFECT UPON THE HOST In general, the causes and types of damage done by parasites to their hosts are: 1. Mechanical damage mainly due to blockages. Heavy infections of Ascaris lumbricoides in children can block the small and large intestine 2. Migration through tissues, penetration into cells. The larger the parasite the greater will be the physical damage to the tissue caused by the movement of the parasite. Possible reasons for parasite migration within the host: The point of infection is not in the area of the parasite’s organ and tissue. The infective larvae of the hookworm’s Ancylostoma duodenale undergo a

process if cutaneous larvae migrans before they reach their definitive site in the gut. The developing stages or larval stages each require a different physiological environment to develop. The larvae of Ascaris lumbricoides hatch out in the small intestine. Larvae undergo a process of visceral larvae migrans and eventually return to the small intestine. 3. Nutrition: depleting the host of nutrients or competing with the host for essential nutrients. The tapeworm Diphyllobothrium can absorb vitamin B12 from the contents of the host’s gut against a concentration gradient and deprive the host. 4. Toxins and negative host response: very often the metabolic waste products of the parasite’s metabolism accumulate in the host tissues and become toxic to the host. Sometimes can stimulate a negative host response, eg. Production of alkaline phosphatase and corticosteroids. 5. Allergic or inflammatory immune reaction by the host to the parasites. In some cases, the host immune response to the presence of parasites or their products causes more injury than do the parasites themselves. 6. Immunosuppression: most parasites are relatively long-lived and continually present an antigenic challenge to the host, reducing the effectiveness of the immune response. OTHER PARASITIC TERMINOLOGIES 1. Ova- female cell within uterus

4. Larvae- active stage pf parasites 5. Trophozoite: motile, feeding stage of protozoan 6. Cyst- non-motile, non-feeding stage of protozoan. Usually has wall to prevent dehydration

PARASITIC PERODICITY 7. Diurnal- day activity parasites 8. Nocturnal: night activity of parasites. PARASITIC LAYING/GIVING BIRTH CHARACTERISTICS 9. Viviparous- parasite that lays larva instead of ova/egg 10. Oviviparous- parasite that lays eggs which hatch before leaving host. 11. Oviparous- parasite that lays eggs which hatch after leaving a host MALARIAL TERMINOLOGIES 12. Microgametocyte: male sex cell of malaria 13. Macrogametocyte: female sex cell of malaria 14: Sporogony: sexual reproduction of malarial parasite, takes place in mosquito 1t. Schizogony: asexual reproduction of malarial parasite, takes place in man.

DISEASE DISTRIBUTION 16. Pandemic- worldwide epidemic 17. Epidemic- outbreak of disease affecting a wide area 18. Endemic- disease which is constant in community

2. Egg- female cell outside uterus 3. Embryo- early developing stage

PARASITIC DEVELOPMENT

19. Encystation- trophozoite into cyst 20. Excystation- cyst emerges into trophozoite

sample using a standard procedure at a set of time after deworming egg reduction rate 

EPIDEMIOLOGIC MEASURES Epidemiology 

is a study of patterns, distribution, and occurrence of disease.

selective treatment 

Incidence 

is the percentage fall in egg counts after deworming based on examination of a stool or urine sample using a standard procedure at a set time after treatment

is a number of new cases of infection appearing in a population in a given period of time.

involves individual level of deworming with selection for treatment based on the diagnosis of infection or on presumptive grounds

Prevalence 

is the number of individuals in a population estimated to be infected with a particular parasite species at a given time

targeted treatment 

Intensity of infection (Worm Burden) 

refers to the number of worms per infected person

Morbidity 

universal treatment 

is the clinical consequences of infections or diseases that affect an individual's well-being.

TREATMENT Deworming 

is the use of anthelminthic drugs in an individual or a public health program

refers to the number (usually percentage) of previously positive subjects found to be egg negative on examination of a stool or urine

is population level deworming in which the community is treated irrespective of age, sex, infection status or other social characteristics

coverage 

Cure rate 

is a group level deworming where the risk group to be treated may be defined by age sex, or other social characteristics irrespective of infection status

refers to the proportion of the target population reached by an intervention. It could be the percentage of school age children treated during treatment day

drug resistance 

is a genetically transmitted loss of susceptibility to a drug in a worm population that was previously

sensitive to the appropriate therapeutic dose

vector or intermediate host propagation and reducing contact between human and infective agent.

effectiveness 

is measure of the effect of drug against an infective agent in a particular host living in particular host, living in a particular environment with specific ecological, immunological and epidemiological determinant

Environmental sanitation 

efficacy 

is the effect of drug against an infective agent in ideal experimental conditions and isolated from any context.

involves interventions to reduce environmental health risks including the safe disposal and hygiene management of human and animal excreta, refuse, and waste water. It also involves the control of vectors, intermediate hosts, and reservoirs of disease.

ERADICATION VS ELIMINATION Disease eradication 

is defined as permanent reduction to zero of the worldwide incidence of infection caused by a specific agent as result of deliberate efforts.

Elimination 

PREVENTION AND CONTROL

is a reduction to zero of the incidence of a specified disease in a defined geographic area as result of deliberate efforts. Continued intervention or surveillance measures are still required.

Morbidity control 

is the avoidance of illness cause by infections. It may be achieved by periodically deworming individuals or group known to be at risk of morbidity.

Environment Management 

is the planning, organizing, performance and monitoring of activities for the modification and manipulation of environmental factors or their interaction with human beings with a view to prevent preventing or minimizing

NOMENCLATURE Animal parasites are classified according to the international code of zoological nomenclature. Each Phylum is divided into: orders, families, genera and spp. At

times, the further divisions pf suborder, superfamily and sub spp are employed.

Parasite infection are either due to unicellular or multicellular protozoan.

Generic name consist of a single word written in initial capital letter The scientific name always begins with small letter. The names of the genera and spp are italized or underlined when written.

Protozoan

(dumb kinky people come over for great sex) (domain, kingdom, phylum, class, order, family, genera, specie)

Major organisms causing disease in man belong to:



nucleus, cytoplasm, an outer limiting membrane and cellular elaborations called organelles

All protozoa fall under kingdom protista

   

Phylum Phylum Phylum Phylum

sarconastigophora Ciliophora apicomplexa Microscopora.

Nematodes 

metazoan parasites are either helminths or arthropods. Helminths causing infections in ma belong to three groups, name annelids, nematodes, and flatworms

Cestodes/tapeworms SYSTEMATIC PARASITOLOGY



FOUR PHYLA OF MEDICAL IMPORTANCE 1. Phylum Protozoa  Single celled animals and ingest food through phagotrophy and absorbing molecules 2. Phylum Nemathelminthes  Multicellular roundworms 3. Phylum Platyhelminthes  Multicellular flatworms 4. Phylum Arthropoda  Medically significant insects Phagotrophy 

Term for Engulfment

Osmotrophy 

Term for absorbing molecules

segmented with a ribbon-like appearance

Trematodes 

group of flatworms composed of the flukes, generally grouped together based on their habitat

Arthropods 

composed of bilaterally symmetrical organism with segmented and jointed appendages...