传染病学英文题目及答案教学提纲.doc

传染病学英文题目及答案

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INTRODUCTION OF COMMUNICABLE DISEASES
I .TERMS
1）Overt infection
It indicates that after the microorganism enters the host, it not only induces the immune responses of the host but also produces hisomorphological damage and pathological changes through the role of the microorganism or the allergic reaction of the host. In most infectious disease such as measles most infected host manifested as overt infection. After overt infection ends the microorganism can be eliminated and the hosts acquitted consolidated immunity. In some infectious diseases (such as bacillary dysentery) the immunity is temporary. A small amount of overtly infected hosts change to carrier state. It is called “convalescent carrier”.
2）Incubation period
This period is from pathogens invading into human body to clinical symptoms appearing. The incubation period of all infectious diseases has a limit of the time (the shortest and longest) and a normal distribution. It is an important evidence of observing, detecting the contact in quarantine work. It is usually equal to the whole period including the pathogen reproduction, transference, location, tissue damage and function changes before the clinical symptoms to occur. The period length is negative relation with the invading quantity of the pathogens. If the pathophysiologic changes are caused by toxins, the incubation period relates with the time of the toxins production and distribution, e.g. bacterial food poisoning. The toxins have been produced before eating. The period can be short to a few hours. The period of rabies determines to the location of virus entry(wound).It has a positive relation with the distance of the wound to the central nervous system. 
3）Latent infection
When the microorganism infected the host and localized in some area of the host, it can latently for along time because the hosts immunity is strong enough to locate the pathogen but can wipes it out. When the hosts immunity decreased, overt infection can occurs. Such latent infection is common in some diseases, e.g. herpes simplex, herpes zoster, malaria, tuberculosis etc. Generally the microorganism can not be excreted during latent infection, which is a different point from carrier state. Not that every infectious diseases has latent infection. 
4）Sources of infection
The microorganisms are able to gain to access to the person or animal, establish itself and proliferate in vivo and excrete pathogen outside the body, such as patients, the person of covert infection, pathogen carriers and infected animals. 
5）Relapse
After the patient has entered convalescent period, the temperature has recovered to normal for a period of time, then the pathogen hidden in some tissue reproduce to a certain degree and make the primary symptoms repeatedly, it is called “relapse”. 
6）Recrudescence
In the convalescent period of some patients, the temperature has not stably decreased to normal and the fever rise again, it is called “recrudescence”.
 7）Zoonoses
Some natural ecologic environment is suitable to the transmission of infectious diseases among wild animals. These diseases include plague tsutsugamushi disease, leptospirosis, and so on. The human race may be infected when he get into these areas. These diseases are called “zoonoses”. 
II. QUESTIONS
1）Please briefly describe the manifestations of infectious diseases (infection spectrum).
Infectious process starts when microorganisms enter the human host through various ways. Whether the microorganism is eliminated or colonized in the host, it is mainly dependent on the pathogenicity of the pathogen and the immune function of the host.
i. Pathogen is eliminated by host immunity: After the microorganism enters the host it can be wiped out by non-specific immunity, and eradicated or eliminated by specific immunity which the host has got before the infectious process.
ii. Covert infection: It refers to that the microorganism only making the host producing specific immune response not having histomorphological damage or even having mild feature after it enters the host. Clinically, there is no any symptoms and signs or any biochemical changes.
iii. Overt infection: It indicates that after the microorganism enters the host, it not only induces the immune responses of the host but also produces hisomorphological damage and pathological changes through the role of the microorganism or the allergic reaction of the host.
iv. Carrier states: It is divided into virus carrier and bacteria carrier according to different pathogens. All carrier states have a common characteristic that is no clinical manifestation but the microorganism can be excreted during the state.
v. Latent infection: When the microorganism infected the host and localized in some area of the host, it can latently for a long time because the hosts immunity is strong enough to locate the pathogen but can not wipe it out. When the hosts immunity decrease, overt infection can occurs.

2）Please briefly describe the factors related to the pathogenicity of the pathogen in the infectious process.
i. Invasiveness: It refers to its ability to invade the host and spread within the host.
ii. Virulence: It includes the toxins and various enzymes.
iii. Number of the pathogen: The number of invading pathogen is positive relation with the pathogenicity in the same infectious disease. The least number of the pathogen to induce disease differ greatly in different diseases.
iv. Variability: Pathogens can produce variation due to environmental and hereditary factors. Generally speaking, under the environment of artificial culture, the pathogenicity of the pathogen will decrease. The repeated spread between the hosts will increase the pathogenicity of the pathogen. The antigenic variation of the pathogen will make the pathogen escape form the specific immunity of the host and continue induce the disease.

3）Please briefly describe the basic characteristics of infectious diseases.
i. Pathogen: Every infectious disease is caused by a specific pathogen including microorganism and parasite. In history many infectious diseases were first understood by their clinical manifestations and epidemiologic feature and then the pathogen was found.
ii. Infectivity: Infectivity means that the pathogen can be excreted to contaminate the surrounding. It is the main distinction between the infectious diseases and other infection. Every infectious disease has considerably a stable infective period, which can be used as a rule to isolate the patient.
iii. Epidemiologic feature: Under the influence of natural and social factors the infectious process manifestates various characteristics. It can be divided into the exoticity and the endemicity. It also can be divided into sporadic, epidemic and pandemic. The distribution of the incidence of the infectious disease in time (seasonal distribution), in space (regional distribution) and different populations (age, sex, and occupation) is also an epidemiologic feature.
iv. Postinfection immunity: The host can produce specific protective immunity which is directed at the pathogen or its products after the host was infected by the pathogen. Postinfection immunity belongs to active immunity. The lasting time of postinfection immunity varies with different infectious.

VIRUS HEPATITIS B
I .TERMS
1) Dane particle
The complete HBV is called Dane particle. The 42-nm Dane particle is made up of an outer shell 7 nm thick, containing the hepatitis B surface antigen, glucoprotein and cellular fat, and an inner core 28 nm in diameter, which possesses its own specific antigen, the hepatitis core antigen (HBcAg). The Dane particle core can be broken down by treatment with detergent to reveal a DNA polymerase and a double stranded circular DNA genome that can serve as a primary template in vitro for the DNA polymerase. 
2) Window phase
Anti-HBc IgM persists 6 to 18 months, so represents an acute response to a newly infection of HBV in acute cases who have cleared the HBsAg but have not demonstrated detectable amounts of anti-HBs, anti-HBc and anti-HBe can be detectable, the serologic gap is called window phase. In this case, anti-HBc IgM may be the only evidence for diagnosing an acute HBV infection. 
3) HBsAg
It stands for Hepatitis B surface antigen. It is coded for the protein of the viral envelope by the S gene. There are four antigenic subtypes of HBsAg. They are adr, adw, ayr, and ayw. HBsAg is non-infectious itself, but HBsAg-positive blood should be considered potentially infectious because it may contain complete HBV (Dane particles). 
4) Chronic HBsAg carrier
Some persons infected with hepatitis B virus develop mild chronic infection state that is asymptomatic and not associated with any significant liver function tests abnormality except persistent serum HBsAg-positive more than 6 months. However, liver biopsy reveals that only a minority of them is with normal histology; and the majority cases present morphologic liver damage in varying degrees, ranging form minimal inflammation, chronic persistent hepatitis, chromic active hepatitis, or even cirrhosis. 
5) HBV DNA
Hepatitis B virus (HBV) contains a small circular DNA molecule that is partially double-stranded, the DNA consists of a long strand (L) of constant length (3,200 bases) in all molecules and a short strand, which varies in length between 1,700-2,800 bases in different molecules. A DNA polymerase activity in the virion repairs the single-stranded molecules of 3,200 bases pairs. The four open reading frames of the HBV are termed S, C, P and X. 
II. QUESTIONS
1) Please briefly describe the regions of the HBV gene and the protein they code for.
The four open reading frames of the HBV are termed S, C, P and X. The S region codes for the protein of the viral envelope and is divided into the S gene, pre-S1 region and pre-S2 region. The C gene codes for the core protein. The P region, codes for the viral DNA polymerase which possesses a reverse transcriptase activity. The X region can code for HBxAg, the function of this region is unknown.

2) Please briefly describe clinical manifestations of the virus hepatitis B.
The clinical picture is extremely variable, ranging from asymptomatic infection, acute hepatitis, chronic hepatitis, cholestatic hepatitis, to a fulminating disease and death in a few days.
i. Acute viral hepatitis
ii. Cholestatic hepatitis
iii. Fulminant hepatitis (Acute gravis hepatitis): Hepatitis may take a rapidly progressive course terminating in less than 10 days. Fulminant hepatitis results form extensive hepatic necrosis. It develops most commonly as a complication of viral hepatitis.
iv. Chronic hepatitis: Chronic hepatitis is defined as hepatic inflammation of at least 6 months duration, as demonstrated by persistently abnormal liver function tests, and divided into three forms: (1) mild chronic hepatitis; (2) moderate chronic hepatitis; (3) severe chronic hepatitis.

3) Please briefly describe the clinical performance of the acute gravis hepatitis.
Hepatitis may take a rapidly progressive course terminating in less than 10 days. Fulminant hepatitis results from extensive hepatic necrosis. It develops most commonly as a complication of viral hepatitis.
The clinical features which suggest a fulminant course are as follows:
(1) high fever, sever abdominal pain, and vomiting, which persist for several days after the initiation of bed rest.
(2) a sudden decrease in the size of the liver.
(3) neuropsychiatric changes of early hepatic encephalopathy, including drowsiness, irritability, insomnia, and confusion.
(4) the appearance of ascites during the acute illness.
(5) severe prolongation of the prothrombin time (more than 20 seconds with control of 12 seconds) with or without bleeding. Serum bilirubin and transaminase levels do not reflect the severity of illness.
(6) patient may die in hepatic coma during the early icteric period, or may become deeply jaundiced, while serum transaminase levels often fall during the period of clinical deterioration.
If the patient occurred above clinical manifestation over 10 days after onset of acute icteric hepatitis, designated subacute gravis hepatitis, the patients easily become cirrhosis.

4) Please briefly describe the clinical meaning of the hepatitis B serum antigen antibody system.
(1) HBsAg (Hepatitis B surface antigen)
It is the marker of HBV infection routinely measured in blood. There are four antigenic subtypes of HBsAg. They are adr, adw, ayr, and ayw. Subtyping of HBsAg is primarily of epidemiologic importance. HBsAg is usually the first detectable abnormality in the serum of a Patient with hepatitis B. It occurs late in the incubation period and before the onset transaminase elevation or symptom, and persists for a few weeks in the typical acute cases, or more than 6 months, even many years in chronic HBsAg carrier state. HBsAg is non-infectious itself, but HBsAg-positive blood should be considered potentially infectious because it may contain complete HBV (Dane particles).
(2) Anti-HBs (Antibody to hepatitis B surface antigen)
It is the antibody to HBsAg and considered to be protective. Anti-HBs usually appears in the serum after HBsAg disappears and persists for years.
(3) HBcAg (Hepatitis B core antigen)
The test for detecting HBcAg from blood is not commercially available.
(4) Anti-HBc (Antibody to hepatitis B core antigen)
It is the antibody to HBcAg and thought not to be protective. Anti-HBc is the first antibody to appear in the serum during infection and is usually first detectable 2 to 4 week after the appearance of HBsAg. Anti-HBc IgM persists 6 to 18 months, so represents an acute response to a newly infection of HBV. It fills the serologic gap (the window phase) in acute cases who have cleared the HBsAg but have not demonstrated detectable amounts of anti-HBs. In this case, anti-HBc IgM may be the only evidence for diagnosing an acute HBV infection.
Anti-HBc IgG developes later than IgM and may persist for many years, even after HBsAg has been cleared. It represents a response to prior infection in HBV.
(5) HBeAg (Hepatitis B e antigen)
HBeAg appears during the incubation period shortly after the detection of HBsAg and only during reactivity, and disappears before the disappearance of HBsAg. HBeAg is a sensitive index of viral replication, infectivity, and chronicity.
(6) Anti-HBe (Anti-body to hepatitis B e antigen)
It is antibody to HBeAg and detected as early as the fourth week of illness. It can persist for years. Anti-HBe is originally thought to be correlated with a low risk of infectivity in HBsAg positive blood.

5) Please briefly describe the management of gravis hepatitis.
(1) The patient with fulminant hepatitis requires intensive nursing care with monitoring and support of vital functions.
(2) Continuous intravenous infusion of glucose solution is required to preven