Hemophilus Infections Health Article

Definition

Hemophilus infections, most of which are due to Haemophilus influenzae infections, are a group of contagious diseases that are caused by a gram-negative bacterium, and affect only humans. Some hemophilus infections are potentially fatal.

Description

H. influenzae is a common organism worldwide; it has been found in the nasal secretions of as many as 90% of healthy individuals in the general population. Hemophilus infections are characterized by acute inflammation with a discharge (exudate). They may affect almost any organ system, but are most common in the respiratory tract. The organism can be transmitted by person-to-person contact, or by contact with nasal discharges and other body fluids. Hemophilus infections in the United States are most likely to spread in the late winter or early spring.

The primary factor influencing the rate of infection is age; children between the ages of six months and four years are most vulnerable to H. influenzae. In previous years, about 50% of children would acquire a hemophilus infection before reaching one year of age; almost all children would develop one before age three. These figures are declining, however, as a result of the increasing use of hemophilus vaccines for children.

Adults are also susceptible to hemophilus diseases. H. influenzaepneumonia is a common nosocomial infection (illnesses contracted in hospitals). The rate of hemophilus infections in the adult population has increased over the past 40 years. The reasons for this change are unclear, but some researchers speculate that the overuse of antibiotics has led to the development of drug-resistant strains of H. influenzae. The risk factors for hemophilus infections among adults include:

• smoking
• alcoholism
• chronic lung disease
• old age
• living in a city or institutional housing with a large group of people
• poor nutrition and hygiene
• HIV infection, or other immune system disorder

Causes and symptoms

Hemophilus infections are primarily caused by Haemophilus influenzae, a gram-negative bacterium that is capable of spreading from the nasal tissues and upper airway, where it is usually found, to the chest, throat, or middle ear. The organism sometimes invades localized areas of tissue, producing meningitis, infectious arthritis, conjunctivitis, cellulitis, epiglottitis, or inflammation of the membrane surrounding the heart. The most serious infections are caused by a strain called H. influenzae b (Hib). Before routine vaccination, Hib was the most common cause of bacterial meningitis, and responsible for most of the cases of acquired mental retardation in the United States.

Hemophilus infections in children

BACTERIAL SEPSIS IN THE NEWBORN. Bacterial sepsis (sepsis is the presence of illness-causing microorganisms, or their poisons, in the blood) is a potentially fatal illness in newborn infants. The child may acquire the disease organism as it passes through the mother's birth canal, or from the hospital environment. H. influenzae can also produce inflammations of the eye (conjunctivitis) in newborn children. The signs of sepsis may include fever, crankiness, feeding problems, breathing difficulties, pale or mottled skin, or drowsiness. Premature birth is the most significant risk factor for hemophilus infections in newborns.

EPIGLOTTITIS. Epiglottitis is a potentially fatal hemophilus infection. Although children are more likely to develop epiglottitis, it can occur in adults as well. When the epiglottis (a piece of cartilage behind the tongue which protects the opening to the windpipe by opening and closing) is infected, it can swell to the point where it blocks the windpipe. The symptoms of epiglottitis include a sudden high fever, drooling, the feeling of an object stuck in the throat, and stridor. The epiglottis will look swollen and bright red if the doctor examines the patient's throat with a laryngoscope (a viewing device).

MENINGITIS. Meningitis caused by Hib is most common in children between nine months and four years of age. The child usually develops upper respiratory symptoms followed by fever, loss of appetite, vomiting, headache, and a stiff or sore neck or back. In severe cases, the child may have convulsions or go into shock or coma.

OTHER INFECTIONS. Hib is the second most common cause of middle ear infection and sinusitis in children. The symptoms of sinusitis include fever, pain, bad breath, and coughing. Children may also develop infectious arthritis from Hib. The joints most frequently affected are the large weight-bearing joints.

Hemophilus infections in adults

PNEUMONIA. Hib pneumonia is the most common hemophilus infection in adults. The symptoms include empyema (sputum containing pus), and fever. The hemophilus organism can usually be identified from sputum samples. Hib pneumonia is increasingly common in the elderly.

MENINGITIS. Meningitis caused by Hib can develop in adults as a complication of an ear infection or sinusitis. The symptoms are similar to those in children but are usually less severe in adults.

Diagnosis

The diagnosis is usually based on a combination of the patient's symptoms and the results of blood counts, cultures, or antigen detection tests.