A brief discussion on introduction to parasites

1. INTRODUCTION TO
PARASITOLOGY
- Dr. Rahul Shrivastava
- (BDS, MPH 2nd Sem)

2. 
 PARASITOLOGY - The branch of biology or
medicine concerned with the study of parasitic
organism.
 PARASITE - An organism which lives in or on
another organism (its host) and benefits by deriving
nutrients at the other's expense.
SOME TERMINOLOGIES

3. 
 PARASITOLOGIST - A scientist who studies parasites
and their biology and pathology, such as the parasitic
diseases caused by them (parasitology). Since parasites
can be observed in practically all animal and plant
phyla, there are specializations for parasitologists
(human, veterinary, plant, etc.).
 PARASITISM - A non-mutual symbiotic relationship
between species, where one species, the parasite,
benefits at the expense of the other, the host.

4. 
 PREDATOR – An organism that attack another
living animal, not necessarily killing them
(attackers).
 PREY – They are the victims.
 HOST - An animal or plant on or in which a parasite
or commensal organism lives.

5. 
 Definitive host: Host in which sexual reproduction takes
place . It is mostly a vertebrate.
 Intermediate host: The host in which some development
of the parasite occurs but it does not reach sexual
maturity, is referred as intermediate host and is usually a
invertebrate.

6. 
 Paratenic or transport (carrier)host: Sometimes the parasite
enters a host in which it does not undergo any development
but remains alive till it gains entry in the definitive host or
intermediate host. These hosts are important for the
completion of the life cycle of certain parasites as they are
believed to bridge the ecological gap between the
intermediate and the definitive host.
 Reservoir host: An organism in which a parasite (that is
pathogenic for some other species) lives and multiplies
usually without damaging the host. For example, dogs and
cats are reservoirs of Leishmania.

7. 
 VECTORS – Hosts that transmit parasites to man.
 BIOLOGIC VECTORS – Those that are essential in
the life cycle.
 PHORETIC/MECHNICAL VECTORS – Those that
are not essential in the life cycle.

8. 
 ZOONOSIS – Disease of animals that are
transmissible to man.
1. Euzoonosis - common to man & reservoir host.
2. Parazoonosis – man is infrequent host & incidental.
3. Anthropozoonosis – infection acquired by man from
other vertebrates.
4. Zooanthroponosis – human infections that may be
acquired by other vertebrates.

9. 
HISTORY
 The father of parasitology -
Platter
 The Italian Francesco Redi,
considered to be the father of
modern parasitology, he was
the first to recognize and
correctly describe details of
many important parasites.

10. 
 "Humans are hosts to nearly 300 species of parasitic
worms and over 70 species of protozoa, some derived
from our primate ancestors and some acquired from
the animals we have domesticated or come in contact
with during our relatively short history on Earth.”

11. We are beginning to learn a lot about the past history of
parasitic infections from studies of archaeological artifacts,
such as the presence of helminth eggs or protozoan cysts
and naturally or artificially preserved bodies; from such
studies has emerged a new science, palaeoparasitology.
Examples of some of these discoveries will be discussed
later.
So vast is the field of human parasitology, and so many and
far-reaching the discoveries made, that it is not possible to
do justice to the whole subject.
Therefore; only the most significant aspects and the most
important parasites are considered under two major
headings, the helminth worms and the protozoa.

12. 

13. 
 Medical Parasitology
 Agriculture, aquaculture & veterinary Parasitology
 Wildlife & Fisheries Parasitology
 Ecological Parasitology
 Biochemistry & Molecular Biology of Parasitology
 Immuno Parasitology
 Quantitative Parasitology
 Structural parasitology
 Taxonomy & Phylogenetics

14. 
PARASITES
A parasite is an organism that lives on or in a host organism
and gets its food from or at the expense of its host. There are
three main classes of parasites that can cause disease in
humans:
1. Protozoa
2. Helminths
3. Ectoparasites.

15. 
 Protozoa are microscopic, one-celled organisms that can
be free-living or parasitic in nature.
 They are able to multiply in humans, which contributes to
their survival and also permits serious infections to
develop from just a single organism.
 Transmission of protozoa that live in a human's intestine
to another human typically occurs through a feco-oral
route (for example, contaminated food or water or person-
to-person contact).
 Protozoa that live in the blood or tissue of humans are
transmitted to other humans by an arthropod vector (for
example, through the bite of a mosquito or sand fly).
PROTOZOA

16. Entamoeba histolytica
A microscope is necessary to view this parasite

17. 
 The protozoa that are infectious to humans can be classified
into four groups based on their mode of movement:
1. Sarcodina – the ameba, e.g., Entamoeba
2. Mastigophora – the flagellates, e.g., Giardia, Leishmania
3. Ciliophora – the ciliates, e.g., Balantidium
4. Sporozoa – organisms whose adult stage is not motile
e.g.,Plasmodium, Cryptosporidium
Classification of Protozoa

18. 
 Helminths are large, multicellular organisms that are
generally visible to the naked eye in their adult
stages.
 Like protozoa, helminths can be either free-living or
parasitic in nature.
 In their adult form, helminths cannot multiply in
humans.
HELMINTHS(Warms)

19. 
1. Flatworms (platyhelminths) – these include the trematodes
(flukes) and cestodes (tapeworms).
2. Thorny-headed worms (acanthocephalins) – the adult forms of
these worms reside in the gastrointestinal tract. The
acanthocephala are thought to be intermediate between the
cestodes and nematodes.
3. Roundworms (nematodes) – the adult forms of these worms can
reside in the gastrointestinal tract, blood, lymphatic system or
subcutaneous tissues. Alternatively, the immature (larval) states
can cause disease through their infection of various body tissues.
4. Some consider the helminths to also include the segmented
worms (annelids)—the only ones important medically are the
leeches. Of note, these organisms are not typically considered
parasites.
Classification of Helminths

21. 
 Although the term ectoparasites can broadly include blood-
sucking arthropods such as mosquitoes (because they are
dependent on a blood meal from a human host for their
survival), this term is generally used more narrowly to refer
to organisms such as ticks, fleas, lice, and mites that attach
or burrow into the skin and remain there for relatively long
periods of time (e.g., weeks to months).
 Arthropods are important in causing diseases in their own
right, but are even more important as vectors, or
transmitters, of many different pathogens that in turn cause
tremendous morbidity and mortality from the diseases they
cause.
ECTOPARASITES

22. An adult louse
Acutal size is about as big as a sesame seed

26. 
 Ingestion
 Arthropods bites
 Penetration of intact skin or mucous membranes
MODE OF ENTRY

28. 
 Some parasites must migrate to certain locations
within the host in order to complete their life cycle.
 Non-human parasites, in humans, often fail to
migrate properly and become “dead-end infections”.
SPREAD OF PARASITES

29.  http://dictionary.reference.com/browse/parasite
 http://www.cdc.gov/parasites/
 http://www.medicinenet.com/script/main/art.asp?articlekey=
4769
 http://journals.cambridge.org/action/displayJournal?jid=PAR
 http://amsocparasit.org/careers/parasitology
 http://link.springer.com/journal/436
 http://www.journals.elsevier.com/international-journal-for-
parasitology/
 http://parasitology.conferenceseries.com/
 http://www.cell.com/trends/parasitology/home
 http://www.sciencedirect.com/science/journal/13835769
 http://knowledgeinbiology.blogspot.in/2010/03/father-of-
various-branches-of-biology.html
REFERENCES