Diphtheria was a world obsession in the 17th-20th centuries, due to its high mortality rate of 10-20% and no cure.
Diphtheria is an infection caused by the bacterium Corynebacterium diphtheriae. Most cases are asymptomatic or have a mild clinical course, but in some outbreaks the case fatality rate has been as high as 10%. In children under five years of age and adults over 40 years of age, this figure can be as high as 20%.
In warmer climates, patients may also develop non-healing skin ulcers covered in gray tissue. The disease is common in Asia, the Dominican Republic, Eastern Europe, Haiti, the South Pacific, and the Middle East.
Diphtheria is spread through airborne droplets containing the bacteria (through sneezing, coughing, and spitting). The bacteria can also live on surfaces an infected person has touched, on open wounds, or on clothing. A person can get diphtheria more than once.
The first cases of diphtheria were recorded in the 5th century BC, spreading terror throughout ancient Egypt and Syria. By the 17th century, the epidemic had spread to Europe, killing hundreds of thousands of people. At that time, diphtheria was called “the hanging disease” (El garatillo in Spanish), and “the throat disease” in Italian.
In 1705, the Mariana Islands experienced a simultaneous epidemic of diphtheria and typhus, which reduced the population to about 5,000. In 1735, the disease swept through America, killing entire families in a matter of days. However, it was not until 1883-1884 that the bacteria causing the disease was discovered.
The diphtheria epidemic in the United States peaked in 1921, with 206,000 cases and 15,000 deaths. In the late 19th century, scientists invented a vaccine, which brought hope to humanity. However, the bacteria continued to cause illness and death in places where vaccination was not widespread.
Diphtheria remains a dangerous infectious disease, especially for children and unvaccinated people. In April, the World Health Organization (WHO) reported an increase in diphtheria cases worldwide. WHO considers this a worrying issue, as the disease can lead to serious complications. In 2019, WHO recorded nearly 23,000 cases of leukemia worldwide, a 2.6-fold increase compared to 2017.
In Vietnam, the disease was quite common in most localities across the country many years ago. In 1981, the diphtheria vaccine was included in the expanded immunization program for free vaccination of children. Since then, diphtheria has been controlled. In 1983, there were nearly 3,500 cases nationwide, but in the period 2004-2019, only 10-50 cases were recorded each year.
However, over the past 5 years, the number of diphtheria cases has increased again. In 2020, 226 cases were recorded, mainly in the provinces of Dak Lak, Dak Nong, Gia Lai, Kon Tum, Quang Ngai and Quang Tri. The number of cases decreased in 2021 (with 6 cases), in 2022 (2 cases) – the year of the Covid-19 pandemic. In 2023 alone, the country recorded 57 cases of diphtheria in the three provinces of Ha Giang, Dien Bien and Thai Nguyen, with 7 deaths – showing a high level of infection and mortality. Recently, the disease appeared in Nghe An, Bac Giang, an 18-year-old female student died.
Diphtheria bacteria. Photo: NFID
Classification of diphtheria
There are two main types of diphtheria, respiratory diphtheria and cutaneous diphtheria.
Classical respiratory diphtheria: This is the most common type and can affect the nose, throat, tonsils, or larynx. Symptoms vary depending on where in the body the membrane is affected. Some people refer to this condition as pharyngeal diphtheria.
Cutaneous diphtheria: This is a rare type of diphtheria, characterized by a skin rash, ulcers or blisters, appearing anywhere on the body. Cutaneous diphtheria is more common in tropical climates or crowded places where people live in unhealthy conditions.
Dangerous complications
Symptoms of diphtheria usually begin two to five days after a person is infected. Signs include a sore throat and hoarseness, swollen glands (lymph nodes) in the neck, difficulty breathing or rapid breathing, runny nose, fever and chills, fatigue, and a thick, gray coating on the throat and tonsils.
In some people, infection with the bacteria that causes diphtheria causes only mild illness or no obvious symptoms. They will pass the disease on to others without knowing it.
If left untreated, diphtheria can cause respiratory complications, heart damage, and nerve damage.
In respiratory complications, diphtheria bacteria produce a toxin. This toxin damages tissue in the immediate area of infection, usually the nose and throat. At that site, the infection produces a tough, gray membrane made up of dead cells, bacteria, and other substances. This membrane can block breathing.
In people with heart damage, diphtheria toxin can spread through the bloodstream and damage other tissues in the body. For example, it can damage the heart muscle, causing complications such as myocarditis (inflammation of the heart muscle). Heart damage from myocarditis can be mild or severe. In the worst cases, myocarditis can lead to heart failure and sudden death.
The toxin can also cause nerve damage. Typical targets are nerves in the throat, where poor nerve conduction can cause difficulty swallowing. Nerves in the arms and legs can also become inflamed, causing muscle weakness.
If diphtheria toxin damages the nerves that help control the muscles used for breathing, they can become paralyzed.