Medical Parasitology Lec.6 Introduction to medical ... · vaginalis, Trichomonas tenax, and...
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Transcript of Medical Parasitology Lec.6 Introduction to medical ... · vaginalis, Trichomonas tenax, and...
Dr. Abdullah Ahmed Hama
PhD. Molecular and Medical Parasitology
1
Sulaimani University College of Pharmacy
Dr. Abdullah A. Hama Microbiology / parasitology & virology Lec. 4 part1
Microbiology/ parasitology and virology
Protozoa/ Class: Mastigophora (Flagelates)
Giardia lamblia
Outline: • Introduction to flagellates
• General characteristic of flagellate.
• Classification of flagellate according to the habitat.
• Giardia lamblia and Trichomonas spices • Morphology and life cycle and transmission
• Pathogenesis
• Disease
• Laboratory diagnosis
• Treatment
• Prevention and control
2
Dr. Abdullah A. Hama Microbiology / parasitology & virology Lec. 4 part1
Introduction • Flagellates: are a major group of parasites with medical importance that inhabit
the intestinal and urogenital tract.
• These organisms have a simple life cycle, and at least three of the following four
species do not have a cyst stage but only a trophozoite stage, during which unlike
many protozoa they are infective. These are Dientamoeba fragilis, Trichomonas
vaginalis, Trichomonas tenax, and Trichomonas hominis, although there are others
that may be found in both cystic and trophozoitic forms, some these organisms may
be characterized by exhibiting an undulating membrane, the most medical
important flagellates are Giardia lamblia and Trichomonas vaginalis.
Dr. Abdullah A. Hama Microbiology / parasitology & virology Lec. 4 part1
General characteristic of flagellates
1- They are protozoan unicellular organisms.
2- They have primitive organelles.
3- They have no organ for digestion, excretion, secretion, etc.
4- The hydro genome are present in most flagellates, that
serve as mitochondria.
5- Characteristic feature of flagellate is Locomotion organ
(Flagella).
Dr. Abdullah A. Hama Microbiology / parasitology & virology Lec. 4 part1
Giardia lamblia
• After that other researchers have named the species of the human (G. lamblia). In 1879, the
first time Giardia was used as a genus name. In 1888, Blanchard suggested the
name Lamblia intestinalis , which Stiles then changed to G. duodenalis in 1902.
Dr. Abdullah A. Hama Medical Parasitology Lec.7 Text book: 978-1-4354-4816-2 Dr. Abdullah A. Hama Microbiology / parasitology & virology Lec. 4 part1
• Giardia was initially described by Van Leeuwenhoek in 1681 as he was examining
his diarrheal stools under the microscope. The organism was described in greater
detail by Lambl in 1859, who thought the organism belonged to the
genus Cercomonas and called Cercomonas intestinalis.
Giardia lamblia
• Giardia lamblia ( Giardia intestinalis, Giardia duodenalis) is a flagellated
unicellular eukaryotic microorganism that commonly causes diarrheal
disease throughout the world. It is the most common cause of waterborne
outbreaks of diarrhea in the United States and is occasionally seen as a
cause of food-borne diarrhea .
• In developing countries, there is a very high prevalence and incidence of
infection, and data suggest that long-term growth retardation can result from
chronic giardiasis . In certain areas of the world, water contaminated with G.
lamblia cysts commonly causes travel-related giardiasis in tourists .
Dr. Abdullah A. Hama Microbiology / parasitology & virology Lec. 4 part1
Morphology
• Trophozoites of G. lamblia are either oval or pear shaped, and the size
ranged from 9 to 21 μm in length and 5 to 15 μm in width.
• The trophozoite form of this organism has been likened to a “monkey face” with
two nuclei as eyes that contain central karyosomes which lack peripheral
chromatin.
• The trophozoite stage is bilaterally symmetrical with an axostyle evenly dividing
the cell down the middle.
• Two curved structures, called median bodies, lie parallel to each other and
perhaps contribute to the metabolism of the parasite.
• Trophozoite
Dr. Abdullah A. Hama Microbiology / parasitology & virology Lec. 4 part1
Morphology
• Cysts : The cyst is oval shape and ranges from 8 to 17 μm length by 7 to 10 μm width.
The karyosomes may be less concentric than those of the trophozoites, and in the mature
cyst, four median bodies are present.
• Longitudinal fibers are visible and four nuclei are seen in the cyst form of G. lamblia.
• There may be a clear zone between the cytoplasm and the cell wall, unlike that of the
trophozoite, are responsible for transmission (infective stage) and can
survive several months out side the host or in water.
• each cyst produces two trophozoites.
Dr. Abdullah A. Hama Microbiology / parasitology & virology Lec. 4 part1
General characteristic of Giardia lamblia •They are unicellular Eukaryotes parasite
• Facultative anaerobes,Carbohydrate metabolism is
anaerobic
• They have not mitochondria
• They are extracellular parasites (intestine)
•They can not invade the host cell.
•They adhere to plasma membrane of host cell
•The contact-dependent cytotoxicity was common in giardia
•The infection cause mechanical damage to host tissues
Dr. Abdullah A. Hama Microbiology / parasitology & virology Lec. 4 part1
Infection with the Giardia lamblia
• Name of pathogen: Giardia duodenalis is the most common name used.
• G. intestinales and G. lamblia are also used.
• Host: can parasitize the intestinal tract of a wide range of vertebrates,
including humans.
• Epidemiology: Disease is prevalent in children attending day care centers.
• In addition the domestic dog and certain wild animals serve as hosts.The
distribution is cosmopolitan (word wide).
• Transmission: Giardia is predominantly transmitted through ingestion of
food or water contaminated with cysts and direct from hand to oral (fecal oral
route) .
Dr. Abdullah A. Hama Microbiology / parasitology & virology Lec. 4 part1
Giardia lamblia
Karyosom
Adhesive disc
Median body Axostyle
Cell wall
Flagella
Dr. Abdullah A. Hama Microbiology / parasitology & virology Lec. 4 part1
Lifecycle of Giardia lamblia
• Infection of a host is initiated when the cyst is ingested with contaminated water or
food and may be through direct fecal-oral contact.
• The cyst is relatively inert (inactive), allowing prolonged survival in a variety of
environmental conditions. After exposure to the acidic environment of the
stomach, cysts excyst into trophozoites in the proximal small intestine.
• The trophozoite is the vegetative form and replicates in the small intestine, where it
causes symptoms of diarrhea and malabsorption. After exposure to biliary fluid,
some of the trophozoites form cysts in the jejunum and are passed in the feces,
allowing completion of the transmission cycle by infecting a new host.
Dr. Abdullah A. Hama Microbiology / parasitology & virology Lec. 4 part1
Dr. Abdullah A. Hama Microbiology / parasitology & virology Lec. 4 part1
Giardiasis Pathophysiology:-
•Giardia colonizes the upper small intestine and cause Villous blunting,
Lymphocytic infiltration and malabsorption.
•No tissue invasion-high number of trophozoites present in the duodenal
cause diarrhea called steatorrhea.
Symptoms:
1.Diarrhea with loose, fool-smelling stools
2.Flatulence
3.Abdominal cramps and bloating
4.Nausea and anorexia
5.Weight loss and Malabsorption
Dr. Abdullah A. Hama Microbiology / parasitology & virology Lec. 4 part1
• Identification of cysts or trophozoites in fecal specimens by direct and indirect
microscopic examination
• Biopsy from small intestine
• Stool culture for G. lamblia growth which is time required an relatively expensive.
•The enzyme linked immune sorbent assay (ELISA) for the detection of Giardia
antigen in fecal specimen is so reliable.
Laboratory Diagnosis
Dr. Abdullah A. Hama Microbiology / parasitology & virology Lec. 4 part1
Metronidazole: (250 mg x 3 for 5-7 day)
Tinidazole- not approved in the US. Single dose of 2 g.
Furazolidone- approved by the FDA for giardiasis
Paramomycin- used for pregnant women
Nitazoxanide: recently approved for giardiasis and cryptosporidosis in
children
Treatment
Dr. Abdullah A. Hama Microbiology / parasitology & virology Lec. 4 part1
Questions? 1. Draw a typical trophozoite of Giardia lamblia with the
basic structure.
2. Explain the pathogenesis of G. lamblia.
3. Write the infective and diagnosis stages of G. lamblia.
4. Enumerate the main flagellates which cause human
infection.
5. Write the laboratory diagnosis methods of Giardia
lamblia .
Dr. Abdullah A. Hama Microbiology / parasitology & virology Lec. 4 part1
Dr. Abdullah Ahmed Hama
PhD. Molecular and Medical Parasitology
18
Sulaimani University College of Pharmacy
Dr. Abdullah A. Hama Microbiology / parasitology & virology Lec. 4 part 2
Classification of Viruses
Classification of Viruses
• Some facts that should be in mind when talking about the process of virus
classification:
A. The amount of information available in each category is not the
same for all viruses.
B. The way in which viruses are characterized is changing rapidly.
C. Genome sequencing data are advancing taxonomic criteria [Gold
standard method] (eg, gene order) and may provide the basis for the
identification of new virus families.
Dr. Abdullah A. Hama Microbiology / parasitology & virology Lec. 4 part 2
Basis of Classification:
1. Virion morphology, including size, shape, type of symmetry, presence or absence of
peplomers (glycoprotein spike on a viral capsid or viral envelope) and presence or absence
of membranes.
2. Virus genome properties, including type of nucleic acid (DNA or RNA), size of genome in
(kb) or (kbp), strandedness (single or double), whether linear or circular, sense (positive,
negative, ambisense), segments (number, size), nucleotide sequence, G + C content, and
presence of special features [repetitive elements, isomerization, 5'-terminal cap, 5'-terminal
covalently linked protein, 3'-terminal poly(A) tract].
3. Physicochemical properties of the virion, including molecular mass, buoyant density, pH
stability, thermal stability, and susceptibility to physical and chemical agents, especially
ether and detergents.
Dr. Abdullah A. Hama Microbiology / parasitology & virology Lec. 4 part 2
4. Virus protein properties, including number, size, and functional activities of structural
and nonstructural proteins, amino acid sequence, modifications (glycosylation,
phosphorylation, myristylation:is a lipidation modification), and special functional
activities (transcriptase, reverse transcriptase, neuraminidase, fusion activities.
5. Genome organization and replication, including gene order, number and position of
open reading frames, strategy of replication (patterns of transcription, translation), and
cellular sites (accumulation of proteins, virion assembly, virion release.
6. Antigenic properties.
7. Biologic properties, including natural host range, mode of transmission, vector relationships, pathogenicity, tissue tropisms (is the cells and tissues of a host that support growth of a particular virus or bacterium), and pathology.
Dr. Abdullah A. Hama Microbiology / parasitology & virology Lec. 4 part 2
Viral Families A. DNA Viruses
Dr. Abdullah A. Hama Microbiology / parasitology & virology Lec. 4 part 2
RNA Viruses
Dr. Abdullah A. Hama Microbiology / parasitology & virology Lec. 4 part 2
Dr. Abdullah A. Hama Microbiology / parasitology & virology Lec. 4 part 2
Dr. Abdullah A. Hama Microbiology / parasitology & virology Lec. 4 part 2
Nomenclature of Viruses
For virus nomenclature, different approaches were followed which are summarized below:
1. Named after the diseases: [Measles virus, smallpox virus……]
2. Name after the places where the disease first reported: [ Newcastle disease virus, Ebola virus,
Norwalk virus, Bunyaviridae]
3. Host and signs of disease: [Tobacco mosaic virus, cauliflower mosaic virus brome mosaic virus]
4. Latin and Greek words: [Coronaviridae – “crown”; Parvoviridae – “small”]
5. Virus discovers: [Epstein-Barr virus]
6. How they were originally thought to be contracted: [Dengue virus (“evil spirit”), influenza virus
(the “influence” of bad air)]
7. Combinations of the above: [Rous Sarcoma virus]
Dr. Abdullah A. Hama Microbiology / parasitology & virology Lec. 4 part 2
The classical methods and terms used in other classification systems for other
microorganisms are not followed in virus classification, and do not obey to the
biological taxonomy.
The virus classification systems are according to the following:
a. Classical system: [Animal, Plant, Bacterial virus]
b. Genomic system: Baltimore classification
c. Serology: Classification based on Diagnostic virology [Infectious
bronchitis virus (IBV) of chickens.
Dr. Abdullah A. Hama Microbiology / parasitology & virology Lec. 4 part 2
Baltimore Classification of viruses
• This system was suggested by David Baltimore, and according to this system
there are seven main classes or groups of viruses. The main criteria depended
in this system are genome type and mode of replication and transcription
Class Description of genome and replication strategy Example of animal virus
I Double stranded DNA genome Herpesvirus, poxvirus
II Single stranded DNA genome Chicken anemia virus
III Double stranded RNA genome Reovirus
IV Single stranded RNA genome plus sense Poliovirus
V Single stranded RNA genome minus sense Influenza virus, Rabies virus
VI Single stranded RNA genome that replicated with DNA
intermediate
Retrovirus
VII Double stranded DNA genome that replicates with RNA
intermediate
Hepatitis B virus
Dr. Abdullah A. Hama Microbiology / parasitology & virology Lec. 4 part 2
Questions??? Thanks
Dr. Abdullah A. Hama Microbiology / parasitology & virology Lec. 4 part 2