微生物學

Microbiology‧Immunology‧Parasitology

■Microbilogy

⊙Blotting method
→most peptides are denatured during electrophoresis, and, of course, nucleic acids have no enzyme activity.
1.Western: identifying specific proteins
2.Southern: identifying DNA fragments（南德日報）
3.Northern: identifying RNA fragments
→The probes are radioactive complimentary strands of nucleic acid. The first of these techniques was the Southern, named for the developer of the procedure, Edward Southern. Northern and then Western blots were named by analogy.

⊙SOS response
→of Escherichia coli is the prototypic DNA damage repair and cell cycle control system, analogous to checkpoint control in eukaryotes. The SOS response includes blocking the cell cycle, global mutagenesis via more than one mechanism, and up regulation of DNA repair and recombination functions.

⊙Bacterial Mechanisms of genetic recombination
1. transformation (the uptake of extracellular DNA),
2. transduction (phages transfer bacterial genes from one host to another)

→general transduction where a small piece of the host's degraded DNA is packaged within a phage capsid. The defective phage injects the host's DNA into a new host. This DNA can replace its homologous region on the host's DNA.

→specialized transduction; this occurs when a temperate phage invades: While exiting the lysogenic cycle the prophage may take adjoining bacterial DNA with it.

3.conjugation (direct genomic transfer between temporarily joined bacterial cells).
→The F Plasmid ("F" means Fertility)

If the F Plasmid integrates into the chromosome, the cell generates a HFR (high frequency of recombination). Reason: HFR transfers F plasmid (episome) as well as some DNA; therefore as the F Plasmid replicates it is spread to other bacteria.

→The R Plasmid ("R" for Resistance)

This plasmid carries genes that code for proteins that destory certain antibiotics. It is transferrable during conjugation.

⊙Operons and Metabolic Control

1.Negative regulation
The lac Operon is an example of inducible negative gene regulation. inducible = initially inactive, made active; negative = switched off by an active protein repressor

2.Positive regulation
This occurs when lactose builds up and there becomes a low glucose concentration.

⊙Catabolic Repression and the Glucose Effect:

→E. coli can use a number of different sugars as energy sources, including glucose and lactose. Glucose is the preferred substrate, and E. coli has elaborate regulation systems to repress other sugar-utilization genes when glucose is present. This repression is called the "glucose effect "or "catabolite repression".

→When glucose is present, it not only inhibits the production of cyclic-AMP but glucose also enhances the transport of cyclic-AMP out of the cell. This causes the concentration of cyclic-AMP to fall dramatically. Without cyclic-AMP, CAP cannot bind near the promoter sites of the various sugar utilizing genes, RNA polymerase will not bind to the promoter sites, and the genes will not be transcribed (or translated).

⊙M13 infection and replication

→a filamentous bacteriophage which infects E. coli host.
→Circular single-stranded DNA
→6400 base pairs long
→The genome codes for a total of 10 genes (named using Roman numerals I through X)
→When M13 phages infect bacterial cells they attach to the F pilus, and the loss of this pilus is a common reason for a failed or poor transformation/transfection of M13.

⊙Proteins Required for Prokaryotic DNA Replication:

1. DNA polymerase III (polymerization, editing)
2. primase (synthesis of RNA primer)（從5到3）
3. helicase (unwinding of helix)
4. single-strand binding protein (stabilization of single-stranded DNA)
5. topoisomerases (relief of super-coil strain)
6. DNA polymerase I (removal of RNA primer, completion of Okazaki fragments)
7. DNA ligase (joining of Okazaki fragments)

⊙Types of bac.
After prolonged cultivation on artificial medium, some cells lose the ability to form the capsule, and the surface of their colonies is wrinkled and rough ("R"). With the loss of their capsule, the bacteria also lose their virulence. Injection of a single S pneumococcus into a mouse will kill the mouse in 24 hours or so. But an injection of over 100 million (100 x 106) R cells is entirely harmless.
L type: loss of cell wall

⊙Peptidoglycan

The bacterial cell wall is a unique biopolymer, it contains both D- and L-amino acids. Its basic structure is a carbohydrate backbone of alternating units of N-acetyl glucosamine and N-acetyl muramic acid.

⊙Staphylococcus aureus:
→coagulase(+), catalase(+)
→Resisting Opsonization via Protein A

The Fc portion of the antibody IgG, the portion that would normally binds to Fc receptors on phagocytes, instead binds to protein A on Staphylococcus aureus. In this way the bacterium becomes coated with a protective coat of antibodies that do not allow for opsonization.

⊙Bordetella pertussis

For culture isolation, Bordet-Gengou agar containing blood, potato extract, and glycerol remains one of the effective means, although minor modifications regarding blood concentrations and addition of penicillin and nicotinamide have been recommended. For routine use, charcoal-blood agar (REGAN-LOWE medium) is most widely used. A (2,6-O-dimethyl)-b-cyclodextrin supplemented STAINER-SCHOLTE broth can be used as an enrichment medium. The Bordetella species do not need factors X and V (NAD+ and hemin).

⊙Brucellae
→facultative intracellular parasites, multiplying mainly in monocyte-macrophage cells. This characteristic dominates the pathology, clinical manifestations and therapy of the disease.
→Brucellosis is a zoonosis, acquired from handling of infected animals or consuming contaminated milk or milk products. Exposure is frequently occupational.

⊙Diphtheria

→Diphtheria toxin can be proteolytically cleaved into two fragments: an N-terminal fragment A (catalytic domain), and fragment B (transmembrane and receptor binding domains). Fragment A catalyzes the NAD+-dependent ADP-ribosylation of elongation factor 2, thereby inhibiting protein synthesis in eukaryotic cells. Fragment B binds to the cell surface receptor and facilitates the delivery of fragment A to the cytosol. 抑制EF2

→C diphtheriae encodes the structural gene for the tox repressor dtxR. In the presence of iron, apo-DtxR becomes activated and binds to the tox operator, thereby preventing transcription. When iron becomes the growth rate-limiting substrate, the iron-repressor complex disociates and the diphtheria tox gene becomes derepressed.

⊙Bacillus Calmette-Guerin (BCG) vaccine
live, attenuated strain of Mycobacterium bovis which was introduced in 1922.

⊙swimming pool granuloma

→crusted, violaceous or hyperkeratotic papulonodule that develops on the dorsal surface of the finger or hand, often a knuckle in this disease. This condition is known as a swimming pool or fish tank granuloma. The granuloma is caused by an atypical mycobacteria, generally Mycobacterium marinum.

⊙Weil-Felix test: scrub typhus (no treat with sulfonamide)

⊙Aflatoxins
mycotoxins (toxic metabolite of fungi), produced by Aspergillus flavus, Aspergillus parasiticus and Penicillium puberulum. These fungi may grow in peanuts (groundnuts), corn and sometimes other nuts and grains, when the temperature is greater than 70°F, relative humidity greater than 70% and grain moisture content greater than 14%. Aflatoxin production requires a temperature of 24-35°C and relative humidity of 80-85%. Fungal growth and toxin production is most likely to occur in improperly stored feed but also occurs on crops in fields, particularly following drought stress, insect damage or mechanical injury. Aflatoxin B1 is the toxin type most commonly found and is the most toxic; it is strongly hepatotoxic (affects the liver) and is also carcinogenic.

⊙Neisseria gonorrhoeae
concomitant roles of pili and colony opacity-associated proteins (Opa) in promoting Neisseria gonorrhoeae adherence to and invasion of human endometrial HEC-1-B cells.（轟趴會得淋病）

⊙Parainfluenzaviruses 1-4:

→Unlike influenza, all the action occurs in the cytoplasm. However, the overall strategy very similar to influenza, although unlike influenza, Paramyxovirus replication is resistant to actinomycin D.
→Cause acute respiratory infections of man ranging from relatively mild influenza-like illness to bronchitis, croup and pneumonia; common infection of children.

⊙Rotaviruses
classified with the Reoviridae family. They have a genome consisting of 11 double-stranded RNA segments surrounded by a distinctive two-layered protein capsid. Six serological groups have been identified, three of which (groups A, B, and C) infect humans.

⊙Coronavirus
The envelope carries three glycoproteins:
S - Spike protein: receptor binding, cell fusion, major antigen
E - Envelope protein: small, envelope-associated protein
M - Membrane protein: transmembrane - budding & envelope formation
In a few types, there is a third glycoprotein:
HE - Haemagglutinin-esterase

Non-segmented, single-stranded, (+)sense RNA, 27-31 kb (dependent on virus) - the longest of any RNA virus. The genome has a 5' methylated cap and 3' poly-A and functions directly as mRNA (unlike (-)sense RNA viruses, no polymerase in particles!) .

⊙E. coli O157:H7
E. coli O157:H7 and similar strains of E. coli (termed enterohemorrhagic E. coli) produce high levels of toxins(Verotoxin) that are indistinguishable from the potent cytotoxin produced by Shigella dysenteriae type 1. These Shiga toxins are produced in the large intestine after ingestion of enterohemorrhagic E. coli. They appear to cause direct mucosal damage, have a toxic effect on endothelial cells in the gut wall blood vessels, and, if absorbed, exert toxic effects on other vascular endothelia (eg, of the kidney(hemolytic uremic syndrome).

⊙Fifth disease
→a common childhood infection causing a slapped cheek appearance and a rash. It is also known as erythema infectiosum.（像被甩兩巴掌）
→caused by Parvovirus B19（台語：打妻virus）. It most commonly affects young children and often occurs in several members of the family or school class. Thirty percent of infected individuals have no symptoms.

⊙不會全身感染的霉菌：Microsporum
不會引起皮蘚病的霉菌：Trichosporon

■Immunology

⊙Hypersensitivity
1.Anaphylactic: IgE(basophil, mast cell)
2.Cytotoxic: IgG, IgM(NK cell)(C8,9 fraction of activated complement/ ADCC)→→→Autoimmune hemolytic anemia/ transfusion, Goodpasture dz, Erythroblastosis fetalis
3.Immune complex dz: Ag-Ab, lysozyme, complememt
4.Cell-mediated(Delayed): T cell

⊙complement
Classical pathway: C1,2,4
Alternative pathway: C3

⊙Negative selection: self tolerance
Positive selection: MHC restriction

⊙Asthma:最先是Mast cell後來才是Eosinophil

⊙Apoptosis

1. Apoptosis triggered by internal signals: the intrinsic or mitochondrial pathway

Bcl-2(on the outer membranes of mitochondria) is bound to a molecule of the protein Apaf-1 ("apoptotic protease activating factor-1". Internal damage to the cell (e.g., from reactive oxygen species) causes Bcl-2 to release Apaf-1; a related protein, Bax, to penetrate mitochondrial membranes, causing cytochrome c to leak out. The released cytochrome c and Apaf-1 bind to molecules of caspase 9. Caspase 9 cleaves and, in so doing, activates other caspases.

2. Apoptosis triggered by external signals: the extrinsic or death receptor pathway

Fas and the TNF receptor(membrane proteins) binding of the complementary death activator (FasL and TNF respectively) transmits a signal to the cytoplasm that leads to activation of caspase 8
(like caspase 9) Example: When cytotoxic T cells recognize (bind to) their target, they produce more FasL at their surface. This binds with the Fas on the surface of the target cell leading to its death by apoptosis.

3. Apoptosis-Inducing Factor (AIF)
a protein that is normally located in the intermembrane space of mitochondria. When the cell receives a signal telling it that it is time to die, AIF is released from the mitochondria (like the release of cytochrome c in the first pathway); migrates into the nucleus; binds to DNA, which
triggers the destruction of the DNA and cell death.

⊙Apoptosis and Cancer

→Several human papilloma viruses (HPV) have been implicated in causing cervical cancer. One of them produces a protein (E6) that binds and inactivates the apoptosis promoter p53.
→Epstein-Barr Virus (EBV), the cause of mononucleosis and associated with some lymphomas
produces a protein similar to Bcl-2

⊙gamma-delta T-cell receptor

most mature T cells residing in the murine intestinal epithelium express CD3-associated TCRs composed of gamma-chains disulphide-linked to a protein resembling the delta-chain. The striking feature of these intraepithelial lymphocytes (IEL) was that they were exclusively CD4-8+.

⊙macrophage-activating factor

Because IL-3 can also participate in the regulation of IL-1 expression, it appears that IL-3 can function as a MAF which selectively regulates the accessory cell characteristics required for Ag presentation, as opposed to the cytolytic functions of the macrophage.

⊙Philadelphia chromosome

→a reciprocal translocation of DNA between the long arms of chromosomes 22 and 9 - t(9;22). The portion of 9q translocated contains abl, a proto-oncogene that is the cellular homolog of a tyrosine kinase coded by the Abelson murine leukaemia virus - ABL.

→The abl proto-oncogene is translocated to a specific site on 22q, designated the break point cluster region - BCR. The unregulated tyrosine kinase activity of the bcr-abl fusion protein (p210) disturbs the growth of a clone of haemopoietic stem cells.

⊙memory T cells

Two types of memory T cell with different migration preferences. Expression of CCR7 and the CD45RA isoform distinguishes three subsets of T cells: naive T cells (CCR7+ CD45RA+); a new subset, which Sallusto et al.- term central memory T cells (TCM: CCR7+ CD45RA-); and effector memory T cells (TEM: CCR7- CD45RA -). Naive T cells migrate very efficiently through lymph nodes using a 'combination code' of L-selectin (an adhesion molecule) and CCR7 (a chemokine receptor). Central memory T cells probably migrate through lymph nodes, whereas effector memory T cells migrate through peripheral tissues such as the skin and mucosa. There are likely to be many combination codes for homing of T cells to the skin and mucosal tissues. CLA, cutaneous lymphocyte antigen.

⊙Five families of cell adhesion molecules

Ig Superfamily
Cadherins
Integrins
Selectins
Transmembrane Proteoglycans

⊙iNOS

→Nitric oxide (NO) is an inorganic, gaseous free radical that carries a variety of messages between cells. Vasorelaxation, neurotransmission and cytotoxicity can all be potentiated through cellular response to NO.

→NO production is mediated by members of the nitric oxide synthase (NOS) family. NOS catalyzes the oxidization of L-arginine to produce L-citrulline and NO. Two constitutive isoforms, brain or neuronal NOS (b or nNOS, type I) & endothelial cell NOS (eNOS, type III), and one inducible isoform (iNOS, type II), have been cloned. All NOS isoforms contain calmodulin, nicotinamide adenine dinucleotide phosphate (NADPH), flavin adenine dinucleotide (FAD), and flavin mononucleotide (FMN) binding domains.

→iNOS is found in a variety of cell types including macrophages, hepatocytes, synoviocytes, and smooth muscle cells. Cytokines such as interferon-gamma (IFN), tumor necrosis factor (TNF), interleukin-1 and -2, and lipopolysaccarides (LPS) cause an increase in iNOS mRNA, protein, and activity levels. Protein kinase C-stimulating agents exhibit the same effect on iNOS activity. After cytokine induction, iNOS exhibits a delayed activity response which is then followed by a significant increase in NO production over a long period of time.

⊙T cell tolerance:

1. Lack of Costimulation

In order to become activated, the T cell must not only bind to the epitope (MHC-peptide) with its TCR but also receive a second signal from the APC. The receipt of this second signal is called costimulation. Among the most important of these costimulators are molecules on the APC designated B7 and their ligand on the T cell designated CD28. The binding of CD28 to B7 provides the second signal needed to activate the T cell.

2. Failure to Encounter Self Antigens

Some tissues hidden behind anatomical barriers that keep T cells from reaching them, Examples of such "privileged sites": interior of the eye ,testes ,the brain. Mechanical damage can breach the barrier and an autoimmune attack follow.

3. Receipt of Death Signals

Some cells of the body express the Fas ligand, FasL. Activated T cells always express Fas. When they encounter these cells, binding of Fas to FasL triggers their death by apoptosis. Macrophages infected with HIV express FasL and thus kill any anti-HIV T cells that try to kill them. This may account for the disastrous decline in CD4+ T cells late in the development of AIDS.

⊙immunoreceptor tyrosine-based activation motif (ITAM) of BCR
Aggregation of the BCR by multivalent antigens initiates transphosphorylation
of the Ig-a/b ITAM motifs and activation of receptor-associated kinases

⊙Antibody
Fab = antigen binding
Fc = receptor for phagocytes

⊙invariant chain
The Class II molecule's path toward the cell surface is somewhat different. In the rough endoplasmic reticulum (RER)the alpha and beta chains associate with each other and a third protein, called the "invariant chain" which stabilizes the complex. Without the invariant chain, the alpha and beta proteins will not associate.

⊙T-independent Antigens

→T-independent antigens are antigens which can directly stimulate the B cells to produce antibody without the requirement for T cell help In general, polysaccharides are T-independent antigens. The responses to these antigens differ from the responses to other antigens.

→Properties of T-independent antigens

1. Polymeric structure - These antigens are characterized by the same antigenic determinant repeated many times.

2. Polyclonal activation of B cells - Many of these antigens can activate B cell clones specific for other antigens (polyclonal activation). T-independent antigens can be subdivided into Type 1 and Type 2 based on their ability to polyclonally activate B cells. Type 1 T-independent antigens are polyclonal activators while Type 2 are not.

3. Resistance to degradation - T-independent antigens are generally more resistant to degradation and thus they persist for longer periods of time and continue to stimulate the immune system.

⊙Decay-accelerating factor (CD55) deficiency

DAF, or CD55, is deficient in red blood cells from patients with paroxysmal nocturnal hemoglobinuria. Classically, it causes increased sensitivity of red cells to lysis by complement due to absence of MIRL and DAF. Interaction of daf with cell-associated c4b and c3b polypeptides interferes with their ability to catalyze the conversion of c2 and factor b to enzymatically active c2a and bb and thereby prevents the formation of c4b2a and c3bbb, the amplification convertases of the complement cascade

■Parasitology

●鑑別診斷

幼蟲（內臟）移行症：犬蛔/鉤蟲
生吃豬肉：旋毛蟲、有鉤條蟲、肝毛線蟲
生吃生魚片：菲律賓毛線蟲
心肌炎：旋毛蟲、弓蟲
Autoinfection:糞線蟲、蟯蟲

●原蟲類

⊙阿米巴
Acanthomoeba spp: 隱形眼鏡，granulomatous amebic encephalitis
Entamoeba histolytica: 痢疾
Entamoeba dispar: non-invasive intestine infection
Naeleria fowleri: 游泳者，meningoencephalitis

⊙瘧原蟲
P.vivax, ovale: easily relapse→treat with Primaquine
P.falciparum: 黑水熱

⊙Trypanosoma cruzi錐鼻蟲
The disease produced is called Chagas' disease and is often overlooked in the differential diagnosis of cardiomyopathy cases. Pseudocysts containing amastigote forms localize in the cardiac muscle.動物錐蟲病及人類昏睡病的主要媒介是吸血昆蟲(如采采蠅)。感染動物包括家畜及野生動物。引起高熱，意識障礙，淋巴節腫脹。

⊙Leishmania: Kala azar, sandfly

⊙弓蟲 (Toxoplasma gondii)
★野貓與家貓是唯一決定性的宿主：他們經由中間宿主一隻傳染過另一隻。中間宿主，包含人類，能夠從只在感染貓的糞便中出現的oocysts或者經由食入感染的bradyzoites或者另一染動物包在組織中的囊狀cystozoites獲得感染。通常臨床症狀可以分為七大類:(1)無症狀或不顯性感染(2)淋巴病變(3)發燒(4)腦炎(5)懷孕時感染弓蟲 (6)先天性弓蟲症 (7)眼睛病變，如再發性或慢性視網膜炎(chorioretinitis)。免疫抑制患者感染弓蟲之症狀特徵為斑丘疹，肺炎，骨骼肌肉病變，心肌炎，腦部症狀以及死亡。而病變外觀與顯微鏡檢查最常發現壞死病變，特別是在：腦、肝、腸繫膜淋巴結。

⊙梨形蟲(Giardiasis)
狗，貓，和靈長類實驗動物大概是最容易感染此人畜共通傳染病的。感染有可能是無徵狀的，但常見有食慾減退喪失，噁心，腹部抽筋，脹氣，和慢性，間歇性腹瀉下痢。雖然本病原罕見發病，嚴重的感染會在膽道膽管及胰管產生發炎以及十二指腸和空腸黏膜受損，造成脂肪和脂溶性維生素的吸收不良。 motility: falling-leaf or rolling motion

●線蟲類(Aschelinthes)

⊙蛔蟲(Ascaris lumbricoides)

受精卵為橢圓形，外覆有一層凹凹凸凸的蛋白膜。卵的兩頂端有空白處，蛋白膜與兩端的空白處都是分辨蛔蟲卵的根據。吃下去的卵在十二指腸孵化成幼蟲，幼蟲穿入十二指腸壁進入血液循環，經肝，心臟，肺在肺泡內發育成第三期幼蟲，再經呼吸道，食道回小腸發育為成蟲。成蟲可受精且排卵。蛔蟲幼蟲移行時對人體會造成傷害。

⊙蟯蟲(Enterobius vermicularis)

寄住大腸。雌蟲會於夜晚主動鑽出消化道在肛門排卵，而排出的卵便在肛門皺摺處發育為成熟卵。Tx:pyrantel pamoate

⊙鉤蟲（Hookworm）

鉤蟲在熱帶及亞熱帶區域廣泛傳播。該蟲的幼蟲是在暗陰潮濕的糞便中殍出來的，幼蟲會在人體內長大為成蟲。當被感染者赤腳走路時，幼蟲便能從他的腳部皮膚進入身體。經皮膚進入人體後，幼蟲便會隨血循環到達肺部，再從呼吸管道達至口部。當幼蟲在口部被吞下，幼蟲便能最終到達受感染者的小腸。Ground Itch這一種皮疹可以由幼蟲穿透皮膚而引起，肺部症狀大都很輕微，但一場大型的疾蟲感染能導致帶有輕微咳嗽和哮喘的肺炎。胃腸道的症狀包括腹瀉、噁心和放屁，可能由於疾蟲在小腸裡成熟而產生，問題往往由於大量的鉤蟲造成更多的失血和由此導致的缺鐵性貧血而產生。治療：Mebendazole (Banworm, Sqworm, Vermox)或Pyrantel Embonate (Combantrim, Early Bird)

⊙糞小桿線蟲(Strongloides stercoralis)

IgE↑↑, rhabditiorm（桿狀！！）

⊙菲律賓毛線蟲(Capillaria philippinensis)

卵花生米狀，兩端有卵塞。成蟲寄生於人的小腸，卵或幼蟲隨糞便排出，卵在水中發育為成熟卵，成熟卵若被中間宿主（魚類）吃入，便在中間宿主體內發育為具感染力的感染型幼蟲。可autoinfection。水樣腹瀉。

⊙鞭蟲(Trichuris trichiura)

鞭蟲卵成檸檬狀，兩端有拴塞。吃入的卵會在小腸孵化，穿入腸黏膜發育，然後在到盲腸寄生。引起貧血，以及脫肛。（檸檬與鞭搞到脫肛）

⊙廣東血線蟲(Angiostrongylus cantonensis)

Barber’s pole pattern為其主要特徵。其幼蟲（IMH）在陸生軟體動物（主要有非洲大蝸牛，扁蝸牛，蝓）或淡水生的軟體動物（如田螺，福壽螺等）中發育，當被★終宿主鼠類（FH）吃入時，幼蟲會移行至腦膜在腦內發育一個月，幼成蟲接者就移行至★肺動脈內發育成熟。人並非終宿主，所以當人誤食入第三期幼蟲，幼蟲鑽入腸壁血管隨血液循環至腦膜，而部會移行到肺臟。幼蟲在人的腦膜內發育至幼成蟲後，很快就死亡，而引起炎症反應。故主要症狀通常是腦膜炎，還有血液和脊髓液內有大量的嗜酸性白血球。此外蟲體可能會侵入眼部，造成眼部疼痛，角膜出血，角膜炎等。通常只能使用症狀治療。

⊙奧氏曼森絲蟲 (Mansonella ozzardi)：蠓 (midge)
幡尾絲蟲病 (onchocerciasis)：蚋 (Simulium sp)河盲症，幼蟲移行皮膚病灶。
羅阿絲蟲 (Loa Loa): 班蛖 (Chrysops)非洲眼蟲，可引起局限性皮膚血管水腫和變應性嗜酸性細胞過多綜合徵.Tx: Diethylcarbamazine

●吸蟲類(The Trematodes)

可能有一個或多個中間宿主,成蟲產出之蟲卵排出宿主體外後會發育成纖毛幼蟲（miracidium）,在水中孵化後侵入另一個宿主,纖毛幼蟲必須侵入正確的第一中間宿主才會繼續生長發育,此第一中間宿主主要為軟體動物（螺獅或蛤蜆）.在軟體動物體內進行一連串的發育增殖,最後產生大量的尾動幼蟲（cercariae）有些則黏附蔬菜植物上,分泌出囊壁形成囊狀幼蟲（metacercariae）,後被終宿主吃入完成生活史。

⊙中華肝吸蟲 Clonorchis Sinensis

有明顯的卵蓋呈花瓶狀外翻。第二中間宿主為★★淡水魚，具有感染性的囊狀幼蟲。經口感染動物及人類。造成腹痛、下痢、膽管炎、膽囊炎、肝肥大硬化。食淡水生魚片感染。必須阻斷其生活史,如撲滅螺絲,勿將人及動物排泄物引入養魚池。治療：praziquantel

⊙衛氏肺吸蟲(Paragonimus westermani)

其卵巢成指狀分支，睪丸亦成指狀分支。體表覆有tegumental spines。在外界發育成纖毛幼蟲，被第一中間宿主（淡水螺）吃入，在螺內經一次胞幼，兩次雷幼，產生尾動幼蟲。排出外界後，在被第二中間宿主（★★淡水甲殼/蝦蟹類）吃入，在第二中間宿主體內發育成囊狀幼蟲，若人吃到含囊狀幼蟲的第二中間宿主及被感染，幼蟲在人體（終宿主）發育為成蟲。通常會有幼蟲皮膚移行現象，主要是成蟲在肺臟寄生時所引起的發炎與發燒。★鐵鏽色痰。

⊙薑片蟲(Fasciolopsis buski)

很有肉感。特點是從頭到尾在腸管兩側有點（泡狀）的，顏色呈黑褐色的卵黃腺。卵最大，有一小卵蓋。在水中若有水生植物（荸薺，★★菱角，茭白，空心菜），尾動幼蟲便會黏上去，發育成囊狀幼蟲。寄生蟲數少實無明顯症狀。但重度感染時就會造成腹痛，腹瀉。因蟲體寄生於十二指腸，所以可能引起腸壁的發炎甚至潰瘍，連帶造成營養吸收不良。治療：Praziquantel

⊙日本血吸蟲（又名東方血吸蟲）(Schistosoma japonicum)

血吸蟲和一般吸蟲不同的是，血吸蟲★雌雄異體。雄蟲有七個睪丸為日本血吸蟲一大特徵。卵有一小側刺。纖毛幼蟲進入合適的中間宿主（★釘螺/螺獅）發育成為尾動幼蟲，再進入外界，此時若尾動幼蟲(Cercaria)鑽入人體，此人及被感染。蟲體會在人體內移行且發育為成蟲，最終寄生於★門脈系統，而雌蟲會排卵於腸道和膀胱。★蟲卵是主要的致病因，因為蟲卵內的纖毛幼蟲會分泌帶有抗原性的酵素，引起宿主寄生不為的傷害或過度的免疫反應。治療：Praziquantel

●條蟲類

⊙圓葉目：有鉤條蟲(Taeniasis Solium)

終宿主為人類，在豬體內肌肉則形成有鉤囊蟲，具有感染性。可經口感染人類，造成腹痛、下痢、頭痛。

⊙擬葉目：廣節裂頭條蟲症 Diphllobothriasis

終宿主為犬等哺乳動物。第二中間宿主為淡水魚，含有感染性的全尾幼蟲。可經口感染人類，引起消化障礙。Pernicious Anemia(Vit B12)。Tx:Praziquantel

⊙Another common feature of the cestode tegument is the presence of bodies called ★calcareous corpuscles.They are composed primarily of calcium which is layered in concentric rings, but also contain magnesium and phosphorus.

⊙圓葉目：Hydatid disease (also called echinococcosis)
→parasite infection caused by the larvae of Echinococcus granulosus, and less frequently by Echinococcus multilocularis (alveolaris) or Echinococcus vogeli.
→E. granulosus infection is prevalent in geographical areas where cattle are raised in association with dogs
→The liver and the lungs are the organs most commonly affected but the larvae may lodge in any other organ of the body. Larvae develop into fluid-filled cysts ("endocyst") that contain an external membrane composed by a chitin-like substance and an inner germinal layer.
→Symptoms may be cough, haemoptysis, pain in the right upper quadrant, jaundice, bone pain and fracture.

●其他

⊙Lyme Disease (Borrelia burgdorferi)

→like the human pathogen Treponema pallidum, is a spirochete
→The medium used to grow Borrelia burgdorferi is called Barbour-Stoenner-Kelly (BSK) medium.
→The outer membrane of Borrelia burgdorferi is composed of various unique outer surface proteins (Osp) that have been characterized (Osp A through OspF). They are presumed to play a role in virulence. Osp A and Osp B are by far the most abundant outer surface proteins.
→Ixodes, commonly known as the deer tick (or bear tick), normally feeds on the white-footed mouse, the white-tailed deer, and certain other mammals.
→erythema migrans, characteristic "bull's eye"appearance, ....may include meningitis, Bell's palsy, cardiac involvement, and migratory pain to joints, tendons, muscle and bone