Haemophilus Influenzae (including Hib)

Clinical Description

Haemophilus influenzae disease, including Hib disease, is caused by the bacterium Haemophilus influenzae. There are six identifiable types of Haemophilus influenzae bacteria (a through f) and other non-identifiable types (called nontypeable). The one that most people are familiar with is Haemophilus influenzae type b, or Hib.

Haemophilus influenzae bacteria, including Hib, are spread person-to-person by direct contact or through respiratory droplets like by coughing and sneezing. Usually the bacteria remain in the nose and throat — causing no harm. Sometimes the bacteria can enter the blood and spread, causing serious infection in the individual. Most of the time, Haemophilus influenzae bacteria are spread by people who have the bacteria in their noses and throats but who are not ill (asymptomatic). The incubation period (time between exposure and first symptoms) ofHaemophilus influenzae disease is not certain, but could be as short as a few days.

Haemophilus influenzae bacteria, including Hib, can cause many kinds of infections. These can range from mild ear infections to severe diseases, like bloodstream infections.  Haemophilus influenzae disease, including Hib disease, causes different symptoms depending on which part of the body is affected. The most common severe types of Haemophilus influenzae disease are:

  •     Pneumonia (lung infection)
  •     Bacteremia (bloodstream infection)
  •     Meningitis (infection of the covering of the brain and spinal cord)

Pneumonia occurs when the lungs become infected, causing inflammation (swelling). Symptoms of pneumonia usually include:

  •     Fever (but older people may have lower than normal body temperature)
  •     Cough
  •     Shortness of breath
  •     Chills
  •     Sweating
  •     Chest pain that comes and goes with breathing
  •     Headache
  •     Muscle pain
  •     Excessive tiredness

Bacteremia is an infection of the blood. It can cause symptoms such as:

  •     Fever
  •     Chills
  •     Excessive tiredness
  •     Pain in the belly
  •     Nausea
  •     Vomiting
  •     Diarrhea
  •     Anxiety
  •     Shortness of breath
  •     Altered mental status (confusion)

Meningitis is an infection of the covering of the brain and spinal cord. In children, teens, and adults, symptoms typically include sudden onset of:

  •     Fever
  •     Headache
  •     Stiff neck
  •     Nausea
  •     Vomiting
  •     Increased sensitivity to light (photophobia)
  •     Altered mental status (confusion)
  •     Infants may appear to be lethargic (limp, loss of alertness) or irritable, or may vomit or feed poorly. In young children, doctors may also test the child’s reflexes, which can be abnormal with meningitis.

Most strains of Haemophilus influenzae bacteria, including Hib, usually live in a person’s nose or throat without causing disease. Severe infections can result when the bacteria invade parts of the body that are normally free from germs, like blood or spinal fluid. This is known as "invasive disease."

Depending on what type of invasive infection the bacteria cause, the complications can be different. For example, if meningitis (infection of the covering of the brain and spinal cord) occurs, a person can suffer from brain damage or hearing loss. Bacteremia (blood infection) can result in loss of limb(s). Many of the infections caused by Haemophilus influenzae bacteria can result in death.

When Haemophilus influenzae bacteria cause a non-invasive infection, like bronchitis or an ear infection, complications are rare and typically not severe. If appropriate, antibiotics will be given to prevent complications. Learn more about using antibiotics for respiratory infections.

Source: http://www.cdc.gov/hi-disease/about/types-infection.html, http://www.cdc.gov/hi-disease/about/symptoms.html,
http://www.cdc.gov/hi-disease/about/complications.html


Diagnosis

The diagnosis of invasive Haemophilus influenzae disease, including Hib, is usually made based on one or more laboratory tests using a sample of infected body fluid, such as blood or spinal fluid.

Source: http://www.cdc.gov/hi-disease/about/diagnosis-treatment.html


Epidemiology

Haemophilus influenzae bacteria, including Hib, are spread person-to-person by direct contact or through respiratory droplets like by coughing and sneezing. Usually the bacteria remain in the nose and throat — causing no harm. Sometimes the bacteria can enter the blood and spread, causing serious infection in the individual. Most of the time, Haemophilus influenzae bacteria are spread by people who have the bacteria in their noses and throats but who are not ill (asymptomatic). The incubation period (time between exposure and first symptoms) of Haemophilus influenzae disease is not certain, but could be as short as a few days.

Haemophilus influenzae disease occurs mostly in infants and children younger than five years of age. Adults 65 years and older are also at higher risk.

People with certain medical conditions are at higher risk for developing a Haemophilus influenzae infection. Those medical conditions include:

  •     Sickle cell disease
  •     Asplenia (no spleen)
  •     HIV (human immunodeficiency virus) infection
  •     Antibody and complement deficiency syndromes
  •     Malignant neoplasms (a type of tumor)


Source: http://www.cdc.gov/hi-disease/about/causes-transmission.html


Prevention

Vaccines

There's a vaccine that can prevent Haemophilus influenzae type b (Hib) disease, but not the other types ("strains") of Haemophilus influenzae. Hib vaccine can prevent Hib meningitis (an infection of the covering of the brain and spinal cord), Hib pneumonia (lung infection), Hib epiglottitis (a severe throat infection), and other infections caused by Hib bacteria. Hib vaccine is recommended for all children younger than 5 years of age in the United States and it is usually given to infants starting at 2 months of age.

There are no vaccines to prevent against the other types of Haemophilus influenzae.

Re-Infection

A child with Haemophilus influenzae disease, including Hib, may not develop protective levels of antibodies. This means that someone could develop a Haemophilus influenzae infection again. Children younger than 24 months of age who have recovered from invasive Hib disease should not be considered protected and should receive Hib vaccine as soon as possible.
Antibiotic Prophylaxis

Sometimes Haemophilus influenzae bacteria spread to other people who have had close or lengthy contact with a patient with Haemophilus influenzae disease. In certain cases, people in close contact with that person should receive antibiotics to prevent them from getting the disease. This is known as prophylaxis. A doctor or local health department will make recommendations for who should receive prophylaxis.

Source: http://www.cdc.gov/hi-disease/about/prevention.html


Available Vaccines

WHO-Prequalified Haemophilus influenzae type b vaccines

 

Common Disease Taxonomy: