Hong Kong Flu: Causes, Outbreak, 4 Risk Factors, Symptoms, and Diagnosis

By | May 14, 2020
Hong Kong Flu

The Hong Kong flu (also known as the 1968 flu pandemic) is an influenza pandemic that took place in 1968 to 1969 and killed approximately one million people around the world.


The disease is caused by the influenza A subtype H3N2 virus, which is derived from H2N2 through an antigenic shift, a genetic process involving various viral subtypes that have undergone a mutation to form new viruses.

Overall, there are three types of influenza viruses that are known to infect humans, namely type A, B, and C. This type of virus is then further divided into subtypes based on Haemagglutinin (H) and neuraminidase (N).

Influenza viruses are generally difficult to predict, as they always change and mutate. This is what caused many variants to arise. This virus was originally only infected with pigs, but later became a viral variant that could infect humans.

Influenza A viruses easily spread in the air, especially through droplet when an infected person sneezes, coughs, or speaks. This Virus can then stick to various objects around the sufferers, such as door handles, water taps, remote control, and so on.

Hong Kong Flu Outbreak

The first record of the outbreak in Hong Kong appeared on July 13, 1968. At the end of July 1968, widespread outbreaks were reported in Vietnam and Singapore. Although the 1957 Asian flu proved deadly, only a slight improvement has been made to handle the epidemic. The Times Newspaper was the first source to sound an alarm about the possibilities of this new pandemic.

Risk Factors

Some groups are more susceptible to more serious impacts when they are infected by the Hong Kong flu. These include

  • Children less than 5 years old, 
  • Older persons aged 65 years or older,
  • Pregnant women, and
  • People with long-term medical conditions (asthma, diabetes, heart disease, decreased immune, and neurological problems).

Hong Kong Flu Symptoms

Hong Kong Flu Symptoms

According to Anthony Fauci, Director of the National Institute of Allergy and Infectious Diseases, influenza A (H3N2) virus are rated the most dangerous compared to other types of influenza viruses. Therefore, you need to recognize the signs and symptoms of Hong Kong flu as follows:

  • Fever as well as body and muscle aches. This occurs due to the response of the immune system in the body to the exposure of influenza A virus that enters the body.
  • Cough and sore throat. This condition is caused by the occurrence of inflammation in the respiratory tract due to viral infections affecting the respiratory tract.
  • Nasal obstruction.
  • Headache.
  • Vomiting and diarrhea. These symptoms often occur in children.

If you have just visited endemic disease areas such as Hong Kong and feel one of the above symptoms, immediately consult the doctor directly what you feel with your physician, so that you can do a thorough physical examination.

With the introduction of symptoms and preliminary examinations, Hong Kong flu disease that strikes you, can be diagnosed and given optimal treatment.

Hong Kong Flu Diagnosis

Clinical Diagnosis based on anamnesis and physical examinations is generally difficult to distinguish the Hong Kong flu with other types of influenza. However, the suspicion of a person is affected by Hong Kong flu if there are two things:

  • There is a history of exposure with pigs, especially if the pigs are sick. This exposure can be direct contact (e.g. Feeding pigs, cleaning pig dung) or indirect contact (e.g. Visiting a pig farm)
  • Close contact (about 6 meters) with the sick person exposed to pigs

To ensure the diagnosis, an antigen examination is possible, such as the rapid Influenza Diagnostic test (RIDT). However, this examination does not ensure the presence of H3N2 virus infection (e.g. It can be caused by other influenza virus variants).

Other tests, such as RT-PCR, may also be able to detect influenza A virus infections, but are unable to distinguish H3N2 subtypes.

Read also: Water in lungs: The causes, symptoms, How to prevent and Treat it

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