Health Topics

Infectious Diseases

Updated: Dec 28, 2021 chinacdc.cn Print
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Infectious diseases are diseases caused by various pathogens that can be transmitted from person to person, from animal to animal or from animal to person. At present, three classes (Class A, Class B and Class C) of notifiable infectious diseases in 40 categories are listed in China.

Also listed are those the National Health Commission has decided to include in the management of Class B and Class C diseases, and infectious diseases that are reported for emergency monitoring according to the management of Class A diseases.



Plague is a virulent infectious disease mainly spread by Yersinia pestis through rodent fleas, a natural focal condition widespread among wild rodents. Clinical manifestations include fever, severe toxemia symptoms, lymphadenopathy, pneumonia, and bleeding.

The plague has appeared as a pandemic many times in the history of the world. In 1992, there were 1,582 cases of human plague reported in nine countries of Brazil, China, Madagascar, Mongolia, Myanmar, Peru, the United States, Vietnam, and Zaire. Most of the patients were concentrated in Africa, and the case fatality rate was 8.7 percent.


Cholera is an acute intestinal infectious disease caused by the O1 serogroup and O139 serogroup Vibrio cholerae. It has caused seven worldwide pandemics since the beginning of the 19th century. After the 1990s, with the emergence of O139, cholera has become more severe globally.


Coronavirus 2019-nCov

Coronaviruses are a large group of viruses that are known to cause diseases. The patients' manifestations vary from the common cold to severe lung infections, such as Middle East Respiratory Syndrome (MERS) and infectious atypical pneumonia (SARS).

The new type of coronavirus (2019 nCoV) that emerged in 2019 has not been previously found in humans. It is currently presenting a high incidence of respiratory tract infections in winter and spring. Individuals must take good health protection, maintain indoor environmental hygiene and air circulation, and minimize activities in public places with poor air circulation or crowds. If you have fever or respiratory tract infection symptoms, please see a medical institution without delay.


Brucellosis is a zoonotic disease caused by bacteria of the genus Brucella invading the body and causing infection-allergic reactions. It has been more than a hundred years since the disorder was first isolated among a group of soldiers who died in 1887. According to a report in the late 1980s, human and more than 160 types of animal hosts of brucellosis have existed in more than 200 countries and regions in the world, distributed on all continents.

Since China first reported two cases of brucellosis in Chongqing in 1905, various levels of prevalence have been found in 29 provinces and municipalities across the country. In the 1950s and 1960s, there was a serious epidemic among humans and animals in China.

Since the 1970s, brucellosis epidemics have declined year by year. By the early 1990s, the human infection rate was only 0.3 percent, and the incidence rate was only 0.02/100,000. This situation was better than that in some developed countries.However, the brucellosis epidemic has rebounded since 1993, and in 1996 the epidemic in some provinces and autonomous regions in China expanded significantly. In 1991, the number of brucellosis outbreaks in China was zero, but in 1996 it had risen to 76; this phenomenon echoes the brucellosis outbreaks in some other parts of the world.

Acquired Immunodeficiency Syndrome

Acquired Immunodeficiency Syndrome (AIDS), caused by HIV, the human immunodeficiency virus (HIV), is a malignant infectious disease with a very high fatality rate. The HIV virus invades the human body and can destroy the human immune system, causing the infected person to gradually lose the ability to resist various diseases, and eventually leads to death. There is no vaccine to prevent it, and there is no effective medicine or method to cure it. AIDS was named in 1982, and its pathogen was discovered in 1983. At present, it is one of the most difficult medical problems.


Rabies is a zoonotic disease (a disease transmitted from animals to humans) and is caused by a virus. Rabies infects domestic and wild animals, and then spreads to people through bites or scratches via infected saliva. Rabies exists on all continents except Antarctica, but more than 95% of human deaths occur in Asia and Africa. Once symptoms of rabies appear, it is almost always fatal.


Tuberculosis is a chronic infectious disease caused by tuberculosis bacteria. Tuberculosis bacteria may invade various organs of the body, but mainly invade the lungs, resulting in pulmonary tuberculosis.

Whooping cough

Whooping cough is an acute respiratory infection caused by Bacillus pertussis. It is more common in infants and young children. At the beginning of the illness, it resembles a cold, with sneezing, coughing, and a little fever. After three to four days, the cough grows heavier. Clinically, it is characterized by paroxysmal spastic cough and cock-like inhalation roar; hence the name whooping cough. The course of the disease can be as long as 2 to 3 months but may be only a few days or a typical 4-6 weeks, or a longer period of two months.


Anthrax is an infectious disease caused by Bacillus anthracis. The disease is an animal infectious disease found in cattle, horses, and sheep, but it can occasionally be transmitted to people engaged in leather and animal husbandry work. The bacteria was first discovered in 1877 by Robert Koch. The spores of Bacillus anthracis can withstand harsh environments such as strong ultraviolet rays and high temperatures. Under a suitable environment, the spores will reactivate and become infectious Bacillus anthracis.

Viral hepatitis

Viral hepatitis is a common infectious disease caused by a variety of hepatitis viruses. It is characterized by strong contagion, complicated transmission routes, widespread epidemics, and high morbidity. The main clinical manifestations are fatigue, loss of appetite, nausea, vomiting, hepatomegaly and liver damage. Some patients may have jaundice, fever, hives, joint pain, or upper respiratory symptoms.

Dengue fever

Dengue fever is an acute infectious disease caused by the dengue virus and transmitted by Aedes mosquitoes. The clinical features are sudden onset of high fever with muscle, bone marrow, and joint pain throughout the body, and extreme fatigue. Some patients may have skin rash, bleeding, and swollen lymph nodes. Epidemic surveillance should be done so that timely measures can be taken to prevent spread.

Patients should be kept away from mosquitoes during the first five days of illness to avoid spread. Typical patients only account for a small part of the source of infection, so simply isolating patients is not enough to stop the epidemic.

The focus of preventive measures is to kill mosquitoes. The public should be mobilized to turn over pots and fill bamboo and tree holes. They should also cover drinking water tanks to prevent breeding of mosquitoes, change the water frequently, and stock mosquito fish in the tank. Indoor adult mosquitoes can be destroyed by spraying with dichlorvos, while outdoor adult mosquitoes can be sprayed with an ultra-low volume of 50% malathion or pyridoxine, or by extensive drug spraying in key areas. Vaccination against dengue fever is still in the research stage and cannot be used in epidemic areas.

Neonatal tetanus

Neonatal tetanus, also known as "four or six winds", "umbilical winds", and "seven days wind", is an infectious disease caused by the invasion of tetanus bacillus from the umbilical area. The main cause of the disease is that the umbilical cord is cut with scissors that have not been strictly disinfected during delivery, or the hands of the delivery person are unclean, or the umbilical cord is not cleaned and disinfected after birth so that it becomes a source of tetanus bacteria.

Encephalitis B

The pathogen of epidemic encephalitis B was discovered in Japan in 1934, hence the name Japanese encephalitis. In 1939, the Japanese encephalitis virus was also isolated in China, and a lot of investigation and research work was carried out after liberation. The disease is mainly distributed in the Far East and Southeast Asia. It has a rapid clinical onset, with high fever, disturbance of consciousness, convulsions, tonic convulsions and meningeal irritation. Severe patients often suffer from after-illness sequelae.

Human infection with H7N9 avian influenzaInfluenza viruses can be divided into three types: A, B , and C. Influenza A can be divided into 1-16 subtypes according to the difference of influenza virus hemagglutinin protein (HA), and 1-9 subtypes according to differences between viral neuraminidase protein (NA). HA Different subtypes can be combined with different subtypes of NA to form different influenza viruses. Birds, especially waterfowl, are the natural hosts of all these influenza viruses, including the H7N9 avian influenza virus. In the past, the H7N9 subtype influenza virus was only found in poultry. There have been poultry outbreaks in the Netherlands, Japan and the United States, but no human infection has been found.


Schisosomiasis is an endemic disease caused by the presence of the adult parasitic schistosome parasitic on the human body. It is mainly prevalent in 73 countries in Asia, Africa, and Latin America, and the number of patients affected is about 200 million. Human schistosomes are divided into four types: S·japonicum, S·haematobium, S·mansoni and S·intetcalatum.Schistosomiasis japonicum is distributed in China, Japan, the Philippines, Indonesia, Thailand and other Asian regions and countries; Schistosomiasis mansoni is distributed in Asia, the Middle East, India and other regions; an interlacing of Schistosomiasis is found in Western Central Africa, Zaire, Cameroon and other countries.


Leptospirosis is an infectious disease of animal origin caused by pathogenic Leptospira. Rodents and pigs are the main source of infection, which is widespread worldwide. Clinically, it is characterized by early Leptospira sepsis, various organ damage and dysfunction in the middle period, and various allergic complications in the later period. Liver and kidney failure and diffuse lung bleeding can occur in severely ill patients, often endangering life.


Syphilis is a chronic, systemic sexually transmitted disease (VD, STD) caused by pale (syphilis) spirochetes. The vast majority of cases result from transmission through sex, and clinically can be manifested as primary syphilis, secondary syphilis, tertiary syphilis and latent syphilis. Their main manifestations are genital erosion, external skin rash, bone pain, skin nucleation and ulceration, and dementia.


Gonorrhea is a sexually transmitted disease mainly manifested by purulent infection of the genitourinary system caused by Neisseria gonorrhoeae (referred to as Gonorrhea). It is an ancient and common venereal disease. In recent years, gonorrhea has ranked first among sexually transmitted diseases in China. Gonorrhea is a gram-negative diplococcus, kidney-shaped and arranged in pairs.

Scarlet fever

Scarlet fever is an acute respiratory infection caused by hemolytic streptococcus. The clinical features are rapid onset, fever, angina, diffuse skin rash, and subsequent peeling. If the treatment is improper or incomplete, allergic complications such as joints and kidneys may occur. It spreads to close contacts through respiratory droplets, and occasionally through bacteria-carrying equipment. The age of onset is most commonly children aged 2-10. Babies within 6 months of age are rarely affected because they acquire passive immunity from their mothers.

Epidemic cerebrospinal meningitis

Epidemic cerebrospinal meningitis is referred to as meningitis. It is a purulent disease caused by meningococcus. The clinical manifestations are fever, headache, vomiting, skin and mucous membrane petechiae, ecchymosis and neck stiffness and other meningeal irritation. The disease was described by Vieusseaux in Switzerland in 1805.

Typhoid fever and paratyphoid fever

Typhoid fever and paratyphoid fever are acute gastrointestinal infectious diseases caused by typhoid bacillus and paratyphoid bacilli A, B, and C. The WHO treats typhoid fever as a global health problem. The incidence in developed countries such as the United States, Western Europe, and Japan has dropped to 0.4 to 3.7 per 100,000.

The focus is on the control of imported cases. WHO estimates that the incidence rate in developing countries can be as high as 540 per 100,000. In China in the 1980s, the incidence rate was 50/100,000. In the 1990s, it was below 10/100,000. The incidence arising from flood disasters in 1998 was 4.8/100,000.

In recent years, the epidemiological characteristics of typhoid fever are as follows: summer and autumn are the peaks (August to October) with the highest incidence of the disease occurring in patients who are 20-40 years old.


Malaria, spread by mosquitoes, is caused by Plasmodium. After a mosquito with a malaria parasite bites the human body, the malaria parasite is injected and the person becomes ill after 10-20 days. Before the onset, there are often symptoms such as fatigue, discomfort, and anorexia. At the onset, there are intermittent stages of chills, fever, and sweating.

Epidemic hemorrhagic fever

Epidemic hemorrhagic fever, also known as hemorrhagic fever with renal syndrome, is a natural foci disease caused by the epidemic hemorrhagic fever virus. It causes widespread epidemics, a high fatality rate and great harm. There are 13 types of human viral hemorrhagic fever in the world. The disease is divided into two categories: kidney damaging and non-kidney damaging.


Measles is the most common acute infectious disease in children. It manifests as flushed gray spots on the oral mucosa. Simple infectious measles is easily cured, but the mortality rate of severely ill patients is relatively high.

Human infection with highly pathogenic avian influenza

Human infection with highly pathogenic avian influenza is an acute respiratory infectious disease caused by some strains of certain subtypes of avian influenza A virus, such as H5N1 and H7N7.In recent years, the H5N1 avian influenza virus spreads globally and continues to cause human disease. It is speculated that this virus may evolve into a virus that can cause a human influenza pandemic through gene reconfiguration or mutation, so it has become the focus of global attention.


Poliomyelitis (polio) is an acute infectious disease caused by the polio virus. The main clinical manifestations are fever, sore throat and limb pain. During a recent epidemic there were more cases of insidious infection and no paralysis, and the incidence of children was higher than that of adults. Before a general vaccine was developed, infants and young children were more affected, so it is also called polio (Infantile paralysis).

Severe Acute Respiratory Syndrome

Severe Acute Respiratory Syndrome is also called SARS. Before the cause was identified, it was called "atypical pneumonia" and it was a very contagious disease. Infectious atypical pneumonia, also known as severe acute respiratory syndrome, is a type of SARS-related coronavirus illness characterized by fever, dry cough, and chest tightness as the main symptoms. In severe cases, rapid progress occurs.

Respiratory failure is a new respiratory infectious disease. The main characteristics of this disease are its extremely strong infectious period and its rapid progress.


Infectious diarrhea

Infectious diarrhea broadly refers to diarrhea caused by intestinal infections of various pathogens. Here, it only refers to infectious diarrhea other than cholera, bacterial and amoebic dysentery, typhoid fever and paratyphoid fever. This group of diseases can be caused by a variety of pathogens such as viruses, bacteria, fungi, and protozoa.


Leprosy is a chronic infectious disease caused by Mycobacterium leprae, which mainly affects the skin, peripheral nerves and the upper respiratory tract in cases of multi-bacterial leprosy (MB). Leprosy spreads mainly through the upper respiratory tract or close contact.


Kala-azar is also known as visceral leishmaniasis. The source of infection human contact and sick or mangy dogs, and it can be spread through sand flies. Sandflies are active during May to August every year. When sandflies suck the blood of patients, the protozoa enter the sandflies and develop and reproduce into flagellates. The protozoa then become parasites in the blood, liver, spleen, bone marrow and lymph nodes of patients.

Hydatid disease

Hydatid disease is the most serious chronic parasitic disease among human tapeworm diseases. Hydatid disease is caused by the human body being infected with the eggs of tapeworms in dogs. The eggs are scattered with dog dung into people's daily environments. In this way, it is easy to contaminate hands, clothes and daily necessities.


Epidemic typhus is an acute infectious disease caused by Rickettsia Prowazeki. Although it has been isolated from goats in Egypt and flying squirrels in the United States, there is insufficient evidence to classify epidemic typhus as a natural focal disease. Epidemic typhus is still a human-lice-human-transmitted disease. Humans are the only host and body lice are the transmission vector.

Typhus is effectively controlled in developed countries, due to the high standard of living, good sanitary conditions, frequent bathing and changing of clothes to prevent the growth of body lice. In developing countries, especially among people who host clothes lice, it is prevalent from time to time.

Acute hemorrhagic conjunctivitis

Acute hemorrhagic conjunctivitis (AHC), also known as epidemic hemorrhagic conjunctivitis and commonly known as pink eye disease, is a new type of acute viral eye disease that has occurred worldwide in the past 30 years. The disease is prevalent in summer and autumn, and is more common in adults. The natural course of the disease is short, and there is currently no special effective treatment.


Rubella is an acute viral infectious disease caused by the spread of rubella virus. It is spread through the respiratory tract and direct contact. Before the advent of a vaccine rubella was distributed worldwide, but it was not easy to be infected if under one year old. The age of onset was mainly 5-9 years old.The biggest hazard of rubella is when the mother is infected with rubella in early pregnancy, especially in the first trimester, causing miscarriage, stillbirth and neonatal congenital rubella syndrome.


Mumps is an acute respiratory infectious disease caused by the mumps virus invading the parotid gland. It can also invade various glandular tissues or the nervous system, as well as the liver, kidney, heart, joints and other organs.


Influenza is an acute respiratory infectious disease caused by the influenza A, B, and C viruses. Influenza A virus often appears in epidemic form, causing a worldwide influenza pandemic. Influenza B virus more often appears in local outbreaks while influenza C viruses mainly appear in scattered locations and generally do not cause epidemics.

Hand, foot and mouth disease

Hand, foot and mouth disease is one of the common infectious diseases caused by the enterovirus. It is more common in summer and autumn, and in infants under five years old. Patients experience fever, papules and ulcers in the hands, feet, mouth and other body parts.

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