Pertussis (whooping cough) د. وجدان اكرم
What is pertussis?
Pertussis, or whooping cough, is a highly contagious bacterial infection that causes an uncontrollable, violent cough lasting several weeks or even months. It is caused by a bacterium that is found in the mouth, nose and throat of an infected person. Pertussis may begin with cold-like symptoms or a dry cough that progress to episodes of severe coughing.Causes of Whooping Cough
The bacterium Bordetella pertussis Fastidious gram-negative bacteria) is the primary whooping cough cause. There are no other causes, and the infection follows no distinct seasonal pattern. People may become infected with the bacteria by breathing in tiny droplets released into the air by an infected person's cough or sneeze. Infection can also result from touching a recently infected surface and then touching one's own mouth, nose, or eyes.
Who gets pertussis?
Pertussis can occur at any age. Children who are too young to be fully vaccinated and those who have not yet completed the primary vaccination series are at highest risk for severe illness. Since the 1980s, the number of reported pertussis cases has gradually increased in the United States. In 2005, over 25,000 cases of pertussis cases were reported in the United States, the highest number of reported cases since 1959. Approximately 60% of the cases were in adolescents and adults and may be a result of decreasing immunity in this population.How is pertussis spread?
Pertussis is primarily spread from person to person by direct contact with mucus or droplets from the nose and throat of infected individuals. Frequently, older siblings who may be harboring the bacteria in their nose and throat can bring the disease home and infect an infant in the household.
Pertussis Pathogenesis:
Primarily a toxin-mediated disease
Bacteria attach to cilia of respiratory epithelial cells
Inflammation occurs which interferes with clearance of pulmonary secretions
Pertussis antigens allow evasion of host defenses (lymphocytosis promoted but impaired chemotaxis)
What are the symptoms of pertussis?
Pertussis begins as a mild upper respiratory infection. Initially, symptoms resemble those of a common cold, including sneezing, runny nose, low- grade fever and a mild cough. Within two weeks, the cough becomes more severe and is characterized by episodes of numerous rapid coughs followed by a crowing or high pitched whoop. A thick, clear mucous may be discharged from the nose. These episodes may recur for 1 to 2 months, and are more frequent at night. Older people or partially immunized children generally have milder symptoms.How soon after infection do symptoms appear?
The incubation period is usually 7 to 10 days with a range of 4 to 21 days and rarely may be as long as 42 days.
When and for how long is a person able to spread pertussis?
If untreated, a person can transmit pertussis from onset of symptoms to 3 weeks after the onset of coughing episodes. The period of communicability is reduced to 5 days after treatment with antibiotics.
What are the complications associated with pertussis?
For children with whooping cough, complications may include difficulty breathing, pneumonia, and seizures. Infants under the age of 12 months who develop whooping cough are more likely to have complications and be hospitalized than people in other age groups. When adolescents and adults get whooping cough, complications that may develop include such things as difficulty sleeping, urinary incontinence, and rib fractures.
Possible Whooping Cough Complications
Possible complications of whooping cough (pertussis) can include:
Middle ear infection (otitis media)
Difficulty breathing
Less oxygen in the blood (hypoxia)
Pneumonia
Seizures
Encephalopathy
Malnutrition
Death.
Whooping Cough Complications in Infants
Infants under the age of 12 months tend to develop the most serious cases of whooping cough, and they are more likely to have complications and be hospitalized than people in other age groups. In the 1990s, about two-thirds of infants reported with whooping cough were hospitalized. Also, infants are more likely to experience pneumonia or convulsions. Infants with whooping cough have the greatest risk of dying as a result of the illness. In recent years, 15 to 21 infant deaths from pertussis have occurred annually.
Parents can help protect their infants by getting a pertussis booster ( HYPERLINK "http://kids.emedtv.com/adacel/adacel.html" Adacel®, HYPERLINK "http://kids.emedtv.com/boostrix/boostrix.html" \o "" Boostrix®) themselves. Parents can also help protect their very young infants by minimizing exposure (close contact) with individuals who have cold symptoms or cough illness. Coughing people of any age -- including parents, siblings, and grandparents -- can have whooping cough. When a person has cold symptoms or cough illness, they need to stay away from young infants as much as possible
Pertussis Among Adolescents and Adults:
Disease often milder than in infants and children
Infection may be asymptomatic, or may present as classic pertussis
Persons with mild disease may transmit the infection
Older persons often source of infection for children
What is the treatment for pertussis?
In general, treatment for whooping cough involves administering antibiotics and providing supportive care. Supportive care may include such things as admission to the hospital, breathing support from a ventilator, and good nursing care. Treatment is also recommended for anyone who comes in close physical contact with an infected person. Do not use over-the-counter cough medicines to try to cure whooping cough.
People with whooping cough (pertussis) should avoid close contact with others particularly infants and children.
The Role of Antibiotics in Treating Whooping Cough
If treatment is begun early enough with antibiotics, the duration of whooping cough symptoms can be decreased. However, in most cases, treatment is not started early enough, so antibiotics do little to help the coughing illness. Antibiotics are still prescribed because they can kill the bacteria in the respiratory secretions, thereby decreasing the risk of spreading the bacteria.
Different antibiotics used for treating whooping cough include:
Erythromycin
Azithromycin
Clarithromycin
Trimethoprim-sulfamethoxazole.
Supportive Care
Supportive care for whooping cough involves treating symptoms and complications that develop. The specific supportive treatment will depend on a number of factors, but can include:
Admission to the hospital
Intravenous (IV) fluids
Oxygen
Breathing support from a ventilator
Prevention of secondary infections
Good nursing care.
Does past infection with pertussis make a person immune?
Neither vaccination nor natural infection with pertussis guarantees lifelong protective immunity against pertussis. Since immunity decreases after 5-10 years from the last pertussis vaccine dose, older children, adolescents and adults are at risk of becoming infected with pertussis and need vaccination.
What is the vaccine for pertussis?
Whole-Cell Pertussis Vaccine:
Developed in mid-1930s and combined as DTP in mid-1940s
70%-90% efficacy after 3 doses
Protection for 5-10 years
Local adverse reactions common
DPT adverse reaction:
(pain, redness, swelling) 20-40%
Temp of 101oF (38.3) 3%-5%
or higher
More severe adverse reactions not common
Local reactions more common following 4th and 5th doses
Adverse Reactions Following the 4th and 5th DTP Dose:
Local adverse reactions and fever increased with 4th and 5th doses of DTP
Reports of swelling of entire limb
Extensive swelling after 4th dose NOT a contraindication to 5th dose
DTP Contraindications:
Severe allergic reaction to vaccine component or following a prior dose
Encephalopathy not due to another identifiable cause occurring within 7 days after vaccination
DTP Precautions:
Moderate or severe acute illness
Temperature >105°F (40.5°C) or higher within 48 hours with no other identifiable cause
Collapse or shock-like state (hypotonic hyporesponsive episode) within 48 hours
Persistent, inconsolable crying lasting >3 hours, occurring within 48 hours
Convulsions with or without fever occurring within 3 days.
Pertussis-Containing Vaccines Storage and Handling :
Stored at 35°–46°F (2°–8°C) at all times
Must never be frozen
Vaccine exposed to freezing temperature must not be administered and should be discarded
Do not be used after the expiration date printed on the box or label
Infants and Children
The childhood vaccine for pertussis is usually given in combination with diphtheria and tetanus. Immunization authorities recommend that DTaP (diphtheria, tetanus, acellular pertussis) vaccine be given at 2, 4, and 6 and 15-18 months of age and between 4 and 6 years of age.
Pre-teens and Adolescents
In 2005, a new vaccine was approved as a single booster vaccination for adolescents and adults called Tdap (tetanus, diphtheria, and acellular pertussis).
The preferred age for routine vaccination with Tdap is 11 or 12 years old. Adolescents, aged 11 through 18 should receive a single dose of Tdap instead of Td (tetanus, diphtheria) for booster immunization against tetanus, diphtheria, and pertussis if they have completed the recommended childhood DTP/DTaP vaccination series.
A single dose of Tdap vaccine is also recommended for children aged 7 through 10 years who are not fully vaccinated against pertussis.
Adults
All adults over 19 years of age who have or who anticipate having close contact with an infant should receive a single dose of Tdap to protect against pertussis and reduce the likelihood of transmission. For other adults aged 65 years and older, a single dose of Tdap vaccine may be given instead of Td vaccine in persons who have not previously received Tdap. Tdap can be administered regardless of interval since the last Td vaccine.
Healthcare personnel, regardless of age, should receive a single dose of Tdap if they have not previously received Tdap and regardless of the time since their most recent Td vaccination.
What can be done to prevent the spread of pertussis?
The single most effective control measure is maintaining the highest possible level of immunization in the community. Treatment with appropriate antibiotics, such as Zithromax, will shorten the time a person can spread pertussis to 5 days after the beginning of treatment. People who have or may have pertussis should stay away from young children and infants until properly treated. Treatment of people who are close contacts of pertussis cases is also an important part of prevention.
What is parapertussis?
Parapertussis is a bacterial illness that is similar to pertussis (whooping cough) but is not as common and generally causes less severe symptoms. Up to 40% of all cases of parapertussis will present with no symptoms. Very young infants (<6 months of age) may have a more severe course of parapertussis than older persons. Parapertussis is spread through the air in droplets produced during coughing and sneezing. A person can be infected with parapertussis and pertussis at the same time. Parapertussis can be distinguished from pertussis by certain laboratory tests. Antibiotic treatment should be started as soon as parapertussis is suspected. All infants less than 6 months of age should receive antibiotics as a preventive measure if they have been in contact with a person who has parapertussis.