It’s 2022, why can’t humans eradicate cholera and plague?

In our country, although cholera occurs every year and has always existed, it tends to be sporadic.

Recently, the Health and Family Planning Bureau of Wuchang District, Wuhan, Hubei reported that a case of infectious diarrhea was diagnosed as cholera at Wuhan University, which attracted attention from all parties.

According to Wuhan University, on the evening of July 12, the blockade management of the dormitory of the School of Engineering of Wuhan University, where a case of cholera had previously occurred, was lifted.

This indicates that this round of cholera epidemic at Wuhan University has been handled and controlled quickly and decisively.

In November 2019, the official website of the Beijing Municipal Health Commission announced that two plague patients from Xilingol League, Inner Mongolia were diagnosed in Beijing and received emergency treatment.

Moreover, although the smallpox virus has been completely eradicated from nature, its close relative, monkeypox, has recently caused a large-scale epidemic spread around the world, with the number of patients reaching thousands. Will this become another smallpox?

The World Health Organization and governments around the world are highly vigilant about this. my country's National Health Commission has also prepared for the worst. Even before the monkeypox outbreak in my country, it has released the "Monkeypox Diagnosis and Treatment Guidelines (2022 Edition)" in advance to prepare for any emergency.

All of the above cannot help but arouse the vigilance and thinking of the public and industry experts. In the post-epidemic era, if some traditional highly contagious diseases that have been basically eliminated re-emerge, what should we pay attention to and how should we respond?

It should be said that in our country, the epidemic situations of traditional highly infectious diseases have been basically controlled.

Cholera is known for its rapid spread, severe symptoms and high mortality rate, and is a plague that people are terrified of.

There have been seven major cholera epidemics worldwide, killing more than 140 million people.

Therefore, cholera, like smallpox and plague, is a highly contagious disease that seriously endangers human health and life, and is a Class A statutory infectious disease that is strictly controlled in my country.

Since the founding of New China, the Party and the State have attached great importance to the prevention and control of infectious diseases, and our country has made great achievements in preventing and controlling cholera epidemics.

In the past ten years, the number of reported cholera cases has dropped by 93%, from 75 cases in 2012 to 5 cases in 2021. This is a remarkable achievement in epidemic prevention and control.

Despite this, the risk of sporadic outbreaks of traditional highly infectious diseases still exists.

Although large-scale outbreaks of highly infectious diseases have been effectively controlled, they have not been completely eliminated, and sporadic cases of traditional highly infectious diseases are still a danger we may encounter in our lives.

Smallpox has been completely eradicated from nature, but cases of cholera and plague still occur from time to time in our country and cannot be taken lightly.

In daily clinical practice, as cases of severe infectious diseases are becoming fewer and fewer, many clinicians are unfamiliar with the clinical characteristics of these infectious diseases, which can easily lead to misdiagnosis and increase the risk of transmission.

Since humans have taken very strict control and prevention measures, why can't we completely eliminate highly infectious diseases such as cholera and plague?

The main reason is that the pathogens of these highly infectious diseases each have some "little tricks" that allow them to evade human epidemic control measures, continue to exist in nature, and from time to time sneak attack humans who relax their vigilance, causing the risk of spreading the epidemic.

Vibrio cholerae can survive outside the human body. El Tor type Vibrio cholerae can survive in warm river water, well water, sea water, as well as fish and shellfish for one to several weeks.

In addition, when Vibrio cholerae infects humans, it can also cause a large number of asymptomatic carriers, and the ratio of asymptomatic carriers to cholera patients can be as high as 10-100: 1. For every cholera patient found, there are at least 10 asymptomatic carriers around him.

Although these carriers do not have symptoms of cholera, they can excrete Vibrio cholerae, contaminating the environment, water and food, causing the spread of cholera. From the perspective of the current implementation of cholera prevention and control measures, it is difficult to detect and control all asymptomatic carriers.

The pathogen of plague, Yersinia pestis, can not only infect humans, but also wild animals such as mice and marmots, and is spread through insects such as fleas.

Plague occurs when humans come into contact with infected wild animals or are bitten by infected insects.

In 2019, an outbreak of rodent plague occurred in August in the area where plague patients lived in Inner Mongolia, which is often a precursor to a human plague outbreak.

However, the management of zoonotic infectious diseases is currently under the jurisdiction of the agricultural and health management departments respectively, and the connection between the two is sometimes not smooth.

The prevention and control measures for human infectious diseases are mainly focused on the management and control of personnel. For the epidemic of wild animals, only a certain degree of monitoring can be achieved, and large-scale active prevention and control measures are rare. This may also cause certain difficulties in the zeroing out of zoonotic infectious diseases such as plague.

So, how can we eliminate the risk of severe infectious diseases? How should we respond to the threat of severe infectious diseases?

I believe that in addition to strictly enforcing the relevant provisions of the existing "Law on the Prevention and Control of Infectious Diseases", the following measures can also be taken:

First, strengthen the depth and breadth of epidemiological surveys.

For the surrounding population and environment where highly infectious diseases occur, strict epidemiological investigation should be carried out to identify asymptomatic infections as much as possible, and strict management and active treatment should be carried out.

Strict disinfection and management shall be carried out on the surrounding environment, drinking water and food that may be contaminated, and other infectious sources such as water bodies that may be contaminated.

Secondly, strengthen the monitoring and management of possible epidemics of wild animals.

In areas affected by zoonotic infectious diseases such as plague, strengthen monitoring of wild animal epidemics and establish and implement a comprehensive graded early warning system.

For areas with major epidemic risks, large-scale elimination of wild rodents or other proactive measures should be taken when necessary to eliminate the risk of human transmission of highly infectious diseases such as plague in advance.

Again, strengthen publicity and education to promote good health and hygiene habits.

In daily life, we should strengthen the dissemination of knowledge about the characteristics and transmission methods of highly infectious diseases, so that the public can be familiar with the characteristics of these diseases and be able to identify them quickly and accurately. At the same time, we should actively promote good hygiene habits such as washing hands frequently, paying attention to food hygiene, and avoiding contact with infected wild animals, so as to enhance the public's awareness of protection and avoid infection by pathogens.

In addition, strengthen education and training for medical staff and improve diagnosis and treatment plans.

In medical education, especially in the qualification examinations for practicing physicians, nurses and pharmacists, requirements for the prevention of highly infectious diseases and related immunological knowledge and skills should be increased so that all medical service workers, including grassroots doctors and nurses, are familiar with the diagnosis and treatment of highly infectious diseases such as cholera and plague, detect epidemics in a timely manner, and take correct and effective treatment and prevention measures.

Finally, actively improve and perfect vaccines and carry out scientific and effective immunization.

By continuously improving the principles and technologies of vaccines, we have developed and produced new varieties of safe and effective vaccines. Early cholera vaccines were mainly inactivated bacterial components for parenteral injection, which were not easy to induce local mucosal protective immunity, had weak infection prevention capabilities, and the protective immunity they induced lasted only for a short period of time, only 3 months. Therefore, the World Health Organization announced in 1973 that the international health quarantine vaccination requirements for parenteral cholera vaccines would be cancelled.

However, immunologists did not give up the research and development of cholera vaccines. Based on the pathogenic characteristics and immune laws of cholera, they successfully developed a variety of oral vaccines based on modern biotechnology engineering (including oral whole-bacterial vaccines, recombinant subunit vaccines, and live attenuated vaccines, etc.) for the prevention of cholera, which significantly improved the effectiveness and safety of vaccines and facilitated scientific and effective vaccination.

Source: China Science Daily, author: Wang Yuedan (Professor of the Department of Immunology, Peking University School of Basic Medical Sciences)