Introduction to Parasites: Classification, General ...

[Pages:30]Classification, General Characteristics of parasites and Medically important Parasites

Parasites

Endoparasite

Protozoa

Metazoa

Ectoparasite Arthropods

Sub kingdom

Protozoa

Phylum

Sarcomastigophora

further divided into

Apicomplexa

no organelle of locomotion

Ciliophora

move by cillia

Microspora

Spore-forming

Sub-phylum

Sarcodina-- -

move by pseudopodia

Mastigophora

move by flagella

Genusexamples Entamoeba

Giardia Plasmodium

Balantidium Enterocytozoa

Speciesexamples E. histolytica

G. lamblia

P. falciparum, P. vivax, P. malariae, P. ovale B. coli

E. bienusi

Classification of Metazoa

Sub kingdom

Metazoa

Phylum

Nematodes

Round worms; appear round in cross section, they have body cavities, a straight alimentary canal and an anus

Class

Platyhelminthes

Flat worms; no body cavity and, if present, the alimentary canal is blind ending

Cestodes

Adult tapeworms are found in the intestine of their host They have a head (scolex) with sucking organs, a segmented body but no alimentary canal Each body segment is hermaphrodite

Trematodes

Non-segmented, usually leafshaped, with two suckers but no distinct head, they have an alimentary canal Schistosomes are the exception, thread-like, and have separate sexes

Genus ? examples

Ascaris (roundworm) Trichuris (whipworm) Ancylostoma (hookworm) Necator (hookworm) Enterobius (pinworm or threadworm) Strongyloides

Taenia (tapeworm)

Fasciolopsis (liver fluke) Schistosoma (not leaf shaped!)

The most common parasitic infection

Parasite

Plasmodium

malaria

Diseases

No. cases

273 million

Soil transmitted helminths:

2 billion

? Roundworm (Ascaris) intestinal obstruction

? Whipworm (Trichuris) Bloody diarrhoea, rectal prolapse

? Hookworm (Ancylostoma and Necator)

Schistosom

Coughing, wheezing, abdominal pain and anaemia

Renal tract and intestinal disease

200 million

Filariae

Lymphatic filariasis and elephantiasis 120 million

Trypanasoma cruzi African trypanosomes Leishamania

Chagas disease (cardiovascular)

African sleeping sickness

Cutaneous, mucocutaneous and visceral leishmaniasis

13 million

0.3 ? 0.5 million

12 million; 2 million new

cases/yr

Deaths/yr

1.12 million 200,000

15,000 Not fatal but 40 million disfigured

or incapacitated 14,000 48,000 50,000

? Intestinal ? Amebiasis .............................. Entamoeba histolytica ? Giardiasis ...............................Giardia lamblia ? Balantidiasis .......................... Balantidium coli ? Crytosporidosis ..................... Cryptosporidium parvum ? Cyclosporiasis .......................... Cyclospora cayetanensis

? Genitourinary tract ? Trichomoniasis ....................... Trichomonas vaginalis

? Blood and Tissue ? Malaria ................................... Plasmodium spp ? Meningoencephalitis ............. Naegleria fowleri ? Toxoplasmosis ........................ Toxoplasma gondii........... (Eye)

? Cardiovascular system ? African Sleeping Sickness ...... Trypanosoma brucei........ (CNS) ? Chagas Disease ...................... Trypanosoma cruzi

? Skin and mucous membrane ? Visceral leishmaniasis( Kala-azar) ... Leishmania donovani ? Cutaneous leishmaniasis .......... Leishmania topica/braziliensis

Medically important Protozoan Diseases

? Gastrointestinal infections

? Amebiasis

Observed ingegsted RBCs indicate pathogenic E. histolytica

? Giardiasis

By Giardia lamblia, an intestinal flagellate A diarrheal disease + Person to person by soiled hands to mouth

? Balantidiasis

By Balantidium coli , the only ciliated protozoan that causes human infection

? Crytosporidosis

By Cryptosporidium parvum A diarrheal disease + Person to person + animal to person

? Cyclosporiasis

By Cyclospora cayetanensis Transmission is Primarily waterborne but + ingestion of contaminated raspberries,

basil and lettuce

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