Communicable diseases

Top 10 Communicable Diseases in 2020

The world has faced a significant challenge over the past few decades with controlling communicable diseases. In the past twenty years, the health sector has been mainly concerned about non-communicable diseases, while we still have the same threat from infectious diseases as we always have. World Health Organisation (WHO) statistics show that about 4 million people die each year from communicable diseases and billions of people suffer from symptoms.

What is a communicable disease?

A communicable disease is simply an infectious disease. It is caused by microorganisms like bacteria, viruses, fungi, or parasites. They can be directly transmitted from one person to another through bodily fluids or blood products, inhalation of contaminated air, and ingestion of contaminated water or foods. Indirect transmission can occur through contact with animals such as pigs, horses, dogs, and even insects.

Why are communicable diseases important?

Even though some parts of the world aren’t significantly affected by communicable diseases, some Asian and African countries suffer immensely. Health sectors in these areas carry the heavy burden of controlling certain communicable illnesses that continue to affect their people.

Unlike non-communicable diseases such as hypertension and diabetes, communicable diseases can be prevented entirely. There are no genetic factors that contribute to communicable diseases. The only method of prevention is avoiding dangerous microorganisms from entering the body. That is achievable with acceptable health practices such as hand washing, proper food handling, water treatment, vaccinations, and avoiding contact with wild animals.

Infectious diseases can be a worldwide threat. Today, it is straightforward and quite common for people to travel openly throughout many countries. With this freedom comes a high chance of spreading disease from one country to another. A recent example is the fast spread of COVID-19 across the globe. There is an alert process for every country in the world if there is an emerging disease moving across borders and threatening lives. The Centers for Disease Control (CDC) is a well-recognized organization located in the United States that is concerned with public health and safety, and specifically with controlling infectious diseases.

What are the most known communicable diseases?

The list of most common communicable diseases can vary by location. Since these are infectious diseases, they are specific to some areas of the world, living conditions, medical access, and even particular periods during the year. The following ten diseases are the most common communicable diseases in the world right now. These diseases have caused a significant number of health care problems for many people around the world.

1. COVID-19

COVID-19 is a novel coronavirus that made history in health care systems around the world beginning in 2019. There are only a few diseases that have placed such a massive burden on the world health systems. In 2020, we are still experiencing the peak of this disease in the United States. COVID-19 is a respiratory tract infection, initially appearing as upper respiratory symptoms like coughing, sneezing, shortness of breath, and sore throat. The symptoms gradually worsen into lower respiratory symptoms like cough with sputum and chest pain while breathing. Intubation and mechanical ventilation are required in severe cases of COVID-19.

Wuhan, China, is the region where this disease was first reported. Although there has been some discussion that this disease was possibly laboratory-made, this idea has been widely accepted as nothing more than a conspiracy theory. Scientists agree that the genetic makeup of this virus shows that it is likely not human-made and resembles other similar coronavirus diseases such as SARS and MERS. Coronavirus was initially found in small mammals like bats. That has led scientists to believe that this specific strain of virus-infected humans through contact with bats.

There are thousands of deaths reported every day from all over the world. Because this disease is highly contagious, a large number of people are becoming affected. The majority of reported deaths from COVID-19 are occurring in people with underlying conditions and comorbidity. However, there are also cases of extreme illness and death in young, seemingly healthy people, including infants and children.

The health sector in every state, country, and region recommends practicing frequent hand washing, wearing face masks, and maintaining social distance to avoid contact with the virus. The recommended method of hand hygiene includes thorough handwashing with soap and water. As a temporary or secondary measure, they also recommend using hand sanitizers that contain at least 70% alcohol to destroy the virus.

COVID19- a communicable disease
Wearing a face mask

2. CRE (Carbapenem-Resistant Enterobacteriaceae)

Enterobacteriaceae are a bacteria species that cause multiple infections in the respiratory tract, urinary tract, bloodstream, and gastrointestinal system. The reason that CRE is very troublesome for the healthcare sector is the carbapenem resistance. Carbapenem is one of the last lines of antibiotics that are used in infections. An illness that shows resistance to carbapenem is a very concerning matter.

You may think CRE is not very common. However, according to CDC statistics from 2017, there were 13,100 reported cases and 1,000 deaths in the United States. People with weakened immune systems and long-term urinary catheters, intravenous catheters, or ventilators are the most susceptible. Typically, healthy people will not contract CRE.

CRE is spread via contact with infected people or those who are colonized. Colonized people carry the germs on their body, but do not have signs or symptoms of illness. Tissues, wounds, and stools of these people are infectious. Healthcare workers who do not wash properly and healthcare equipment that is not disinfected correctly can also be sources of infection.

Because CRE is less responsive to most antibiotics, the treatments are dependent on clinical judgment.

3. Ebola

Ebola virus disease (EVD) was initially found in 1976. Since then, reported cases are mainly confined to the Sub-Saharan region of the world. Ebola can quickly become an outbreak with a massive health burden.

The source of the virus has not yet been discovered, but there are similar viruses found in apes, chimpanzees, and other nonhuman primates. Contact with these would be the cause of an initial cause, but from there, the infected person will also be a source for spreading the illness. Contact with the body fluids of an infected patient, including their saliva, urine, blood, and semen, can spread the disease.

Health care providers and travelers to virus endemic areas are at particular risk. The virus can be persistent within the body, hidden in special tissues that are immunological like cerebrospinal fluid, testes, and placenta.

Ebola virus prevention can be done by hand washing, avoiding contact with anyone infected, and using protective measures while handling patients and contacting body fluids. Additionally, there is a vaccine that was approved by the FDA in December 2019 for virus prevention.

4. Hantavirus

Hantavirus is a communicable disease that is spread to humans via rodent urine, droppings, or saliva. Cotton rat, deer mouse, white-footed mouse, and rice rat are the main varieties of rodents identified as causing the disease in the United States.

Hantavirus disease has two main presentations. Hantavirus Pulmonary Syndrome is the main presentation that initially causes fatigue and muscle pain. Later, the patient will develop a cough with sputum and chest tightness. A chest x-ray may reveal that fluid has filled in the lung bases. The disease may be a fatal condition, according to statistics showing a 38% rate of mortality.

Haemorrhagic Fever with Renal Syndrome (HFRS) is the second entity that is less common, but much more severe. These patients can get symptoms ranging from abdominal pain, rash, low blood pressure, acute shock, and acute renal failure.

Hantavirus can be contracted in a rodent’s natural habitat like stores and warehouses, urban alleys and tunnels, barns, and camping sites. Rodent bites are the leading cause of being infected with hantavirus disease. In some regions, where food and water quality are problems, eating or drinking food and water contaminated from rat urine and feces are also recognized sources of the illness. House cleaners, campers, and hikers, as well as construction workers, are at the highest risk of contracting the disease.

5. Tuberculosis (T.B.)

If someone asks about the world’s oldest reported disease, tuberculosis is the answer. Scientists had found that even before 15,000 years ago, tuberculosis was present in humans. Egyptian mummies, which date from 2400 – 3400 B.C., showed evidence of T.B. bacteria in their spines. There is a T.B. prevention campaign that is conducted by the World Health Organization (WHO). In 2018, world health statistics showed that about 10 million people had tuberculosis, and 1.5 million had died from the disease.

Tuberculosis is caused by a bacteria called Mycobacterium tuberculosis. It is spread through aerosols in the air from speaking, coughing, sneezing, etc. Once the bacteria enters into our body, it can present as night sweats, a chronic cough lasting for 3-4 weeks, and weight loss. In some cases, the bacteria can live in our cells without causing the disease. That is called a latent phase of the bacteria, and it can be reactivated when the patient gets another severe illness, and his immunity drops. The latent T.B. can spread throughout the entire body by causing small cavities within the organs.

Although an effective treatment method for T.B. was used for an extended time, it required some dedication from the patient. If the patient only gets pulmonary T.B., the treatment course must continue for six months. For other T.B. cases, it is a 12-month treatment period. Because it is difficult to adhere to this schedule, the more common treatment method is taking prescription drugs under the observation of a trained medical professional.

TB as a communicable disease


Human immunodeficiency virus (HIV) is a group of viruses that cause acquired immunodeficiency syndrome (AIDS). HIV is a serious health issue around the world. In 2018 there were 38 million people across the globe with HIV. There were 1.7 million new cases of HIV in 2018, representing a 23% decline in cases since 2010. Sub-Saharan Africa is the most affected region globally, with approximately 20.7 million cases in 2019 (54% of world cases). The vast majority of people with HIV are from low- and middle-income countries.

HIV is transmitted through blood and blood products, contact with mucus membranes, rectal fluids, semen, pre-seminal fluids, and syringes. The most popular myths are that HIV can be transmitted through air or water, saliva, sweat, tears, or closed-mouth kissing, through insects or pets, and sharing toilets, food, and drinks. HIV is indeed more prevalent in gay and bisexual men, mostly young African-American men who have the highest rates of transmission.

Safe sex practices, avoiding IV drug abuse, and safe health care practices prevent the spread of HIV. Continuous use of antiretroviral treatments is the main component in preventing the disease and living with HIV. People with HIV suffer from significant social stigma, even more so than from the disease. This stigma can be so devastating that is results in suicides. Therefore, HIV patients must have a good social support network.

7. Rabies

Rabies can be fatal, but it is an entirely preventable disease if attended to in time. Bats, raccoons, foxes, and other wild animals are the primary sources for rabies in developed countries. But there are also countries where dog bites are still the most common incidents that cause rabies.

Bites, scratches, and contact with the saliva of these animals are the sources for getting the disease. The rabies virus can enter into our nervous system and gradually ascends to the brain. The virus multiplies and causes inflammation within the brain. This process can take weeks to months. After the brain is affected, patients show symptoms of the disease such as abnormal behavior, confusion, seizures, weakness, and paralysis. When the virus gets to the salivary glands, it is then that they are infectious. Coma and death can come if left untreated.

The treatments for rabies are not too difficult to follow. There are pre-exposure treatments suitable for people who handle animals regularly, such as veterinarians, zookeepers, and biologists. Taking post-exposure treatments will help to control the rabies infection quite effectively if given as soon as possible. A fast-acting shot can be provided near the area where an animal bite occurs to prevent the virus from infecting the person.

8. Smallpox

Smallpox is a disease that the world health care system has made considerable strides in eradicating. The naturally occurring disease has all but disappeared since 1975. But still, the health sector is alert about any chance of the disease emerging and have plans to act immediately.

The cause of smallpox is still unknown. That is a viral disease that causes flu-like symptoms and skin rash. It is highly contagious from the first vesicle appearance to the last scab on the skin. Personal direct contact, contact with personal belongings of a patient, aerosol from cough and sneeze, and saliva are the primary sources for spreading the disease. Statistics showed that about 3 out of 10 patients die from smallpox.

There is no cure for smallpox. Vaccines control smallpox. Although, nowadays, the vaccine is not injected regularly. A vaccine can prevent it, but the side effect risk is too high to justify routine vaccination for people at low risk.

There has been a conversation that smallpox can be used as a bioweapon. However, this concept is debatable.

9. Leprosy

Leprosy is a chronic disease that causes neurological symptoms. Leprosy is caused by a bacteria called Mycobacterium leprae. Leprosy is contagious in close contacts. It was reported mainly in World War 2, spreading in soldier dormitories. After the bacteria enters the body, it multiplies within the nerves. That takes a long time. Numbness over certain areas, finger deformities, and lion-like faces are the most common symptoms of the disease.

Leprosy is treated with several antibiotic combinations. Currently, leprosy is successfully under control worldwide.

10. Typhoid fever

Typhoid is a disease-causing digestive tract symptom like abdominal pain, diarrhea, constipation, and loss of appetite. This disease is caused by two primary organisms which are Salmonella typhi and Salmonella paratyphi. The disease is spread by ingesting contaminated food or water in places where the disease is prevalent. These places include parts of East and Southeast Asia, Africa, the Caribbean, and Central and South America. People traveling to any of these areas should consult a doctor before traveling to get a vaccination.

Currently, there is an ongoing outbreak of typhoid fever in countries like India and Pakistan. It is advisable to get vaccinated and practice good hand hygiene to avoid contact with typhoid.

Typhoid fever as a communicable disease
Typhoid fever

This list covers 10 of the most common communicable diseases in the world. Few have been eradicated successfully, but most are still causing severe problems in regions around the world. It is important to teach healthy habits that protect people from disease and prevent them from spreading.


Bonus video: 10 Most Common Communicable Diseases Your Child Can Pick Up at School

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