Pertussis

 

by Reid Bishop

Pertussis (Whooping Cough); Etiological agent- Bordetella pertussis (2).

 

Transmission:

 

Through direct contact with the respiratory discharges of infected people. Usually carried by aerosol droplets when people sneeze, cough, or while talking (2).

 

Reservoirs:

 

Infected adolescents and adults

 

General Characteristics:

 

 Gram-negative coccobacillus. It is distinguished from Bordetella parapertussis because it is oxidative positive and urease negative while B. parapertussis is oxidative negative and urease positive (1). Pertussis can be further identified by several testing methods. It can be cultured on conventional plating, be identified by Pulse Field Gel Electrophoresis and DNA sequencing (8). Direct Fluorescent Antibody testing is another method in which pertussis can be identified, but it is generally not as specific as other tests (10). The CDC only recognizes culture and PCR identification of pertussis (10).

 

Signs and Symptoms:

 

After a person is infected there is about a 7-10 day incubation period. After this the catarrhal stage sets in with possible coughing, sneezing, and mild symptoms of rhinitis. This usually continues for 1-2 weeks. The organisms continue to grow and the intensity of the symptoms increases. Next is the paroxysmal stage which is characterized by a violent cough followed by an inspiratory gasp which is where the disease earns its name. This may last for a few weeks. The patients may have difficulty eating and drinking, and swallow excess mucus which can lead to vomiting and dehydration. Hypoxia is a characteristic and can lead to seizure, hypoxic encephalopathy or coma. Some secondary complications include pneumonia, rectal prolapse, otitis media, and meningo-encephalitis. Untreated pertussis can result in death (1).

 

Virulence Mechanisms:

 

Exotoxins- Pertussigen: this toxin released is an oligopeptide A-B exotoxin. It leads to T cell lymphocytosis, hypoglycemia, increased IgE synthesis and increases sensitivity to histamine and endotoxins. B. pertussis inhibits cellular communication such as chemotaxis, phagocytosis, respiratory burst, and affects NK cell killing ability. By inhibiting the deactivation of adenylate cyclase, large amounts of cAMP accumulate causing mucus secretion.

Adenylate cyclase exotoxin: this exotoxin enters host cells and catalyzes the conversion of ATP to cAMP, leading to the secretion of mucus. This toxic effect does not last as long as pertussigen. It also inhibits NK cell and phagocyte functions.

Tracheal cytotoxin: this peptidoglycan-like molecule inhibits ciliary movements and can lead to the destruction of ciliated cells (1).

 

Demonectrotic toxin: this toxin is a vasoconstrictor, causes ischemia, extravasation of leukocytes and necrosis of tracheal tissue.

Filamentous hemagglutinins (agglutinogens): these are surface-associated adherence proteins that allow B. Pertussis to bind to ciliated cells in the respiratory tract.

Endotoxins- Lipopolysaccharide (LPS): As other endotoxins, when released in large amounts these can cause shock and cardiovascular collapse. They activate inflammatory mediators of the immune system such as TNF, IL1, IL6, prostaglandins and stimulate complement proteins (3).

 

Control/Treatment:

 

 Infected individuals should be isolated to prevent further contamination. Erythromycin, trimethoprim-sulfmethoxazole, azithromycin, and clarithromycin are all accepted antimicrobials that have shown to effectively treat pertussis if initiated within 2 weeks of the cough onset. However, if the disease reaches the paroxysmal stage, treatment is primarily aimed at preventing the spread to other individuals (2).

There are four combination vaccines that are used to prevent diptheria, tetanus and pertussis (DTP). They include DTaP, Tdap, DT, and Td. The upper and lowercase letter denote the strength of the doses while the “a” stands for “acellular.” Acellular means that only part of the B. pertussis is used to stimulate antibody production. Two, DTaP and DT, are given to younger children (under 7 years old) and two, Tdap and Td, are given to individuals7 years old and older. There are a series of 5 vaccination shots that should be administered at ages 2, 4, 6, 15-18 months old, and a final one between 4-6 years old (4).

 

Current Information:

 There have been several outbreaks within the past decade resulting in deaths. There were outbreaks in the Democratic Republic of the Congo in 2000 and 2001. During the 2000 outbreak, 1136 people were infected and 23 died. During the 2001 outbreak there were 2633 cases with 17 deaths. In 2003 there was an outbreak in Afghanistan where 115 cases were reported with 17 deaths. Sudan had outbreaks in 2004 and 2005. During the outbreak in 2004, over 300 people died and the case number was unknown. In 2005, 419 cases and 13 deaths were reported. Following each of these outbreaks, health officials made attempts to provide vaccination campaigns to prevent the disease within the country (5).

There was an outbreak in Illinois in 2001 where 191 cases were reported in an oil refinery (7).

There was also an outbreak in Pike Country, Arkansas in 2001. In this outbreak there was 140 cases reported while 77 were of students in the school system.

There were 152,535 cases reported in 2007. In 2002 there were 294,000 estimated deaths reported (6).  It is estimated that there are 45 million cases and 400,000 deaths per year (7).

Within Texas, in 2006 there were a total of 954 cases of Pertussis outbreaks with an incidence rate of 4.1 (9).

There are about 5,000-7,000 cases per year in the US with a gradual increase in infections since 1980 (2). In 2002 there was an incidence rate of 3.01/100,000 per year (2).

 

Works Cited:

 

1.   "BACTERIOLOGY - CHAPTER EIGHTEEN ." Microbiology and Immunology Online. July  3, 2007. Univeristy of South Carolina School of Medicine. 8 Dec 2008 http://pathmicro.med.sc.edu/ghaffar/bord-hemo.htm

.

2.   "Pertussis." Department of Health and Human Services: Centers for Disease Control and Prevention. 13 October 2005. Department of Health and Human Services- Centers for Disease Control and Prevention. 6 Dec 2008  http://www.cdc.gov/ncidod/DBMD/diseaseinfo/pertussis_t.htm

 

     3. Fedele, Gioirgio, Nasso, Maria, Spensieri, Fabiana, Palazzo, Raffaella, Frasca, Loredana, Watanabe, Mineo, Ausiello, Clara M.. "Lipopolysaccharides from Bordetella pertussis and

          Bordetella  parapertussis Differently Modulate Human Dendritic Cell Functions Resulting  in Divergent Prevalence of Th17-Polarized Responses." July 2008. The Journal of  Immunology. 5 Dec 2008  http://www.jimmunol.org/cgi/content/abstract/181/1/208

 

     4. "Pertussis (Whooping Cough)." Pertussis: Gram-Negative Bacilli: Merck Manual Professional. November 2005. Merck and Co., Inc.. 8 Dec 2008           http://www.merck.com/mmpe/sec14/ch173/ch173l.html

 

     5. "Managing pertussis outbreaks during humanitarian." February 2008. World Heath Organization. 8 Dec 2008     http://www.who.int/diseasecontrol_emergencies/EPR_DCE_2008_2.pdf

.

     6. "Pertussis." Immunization surveillance, assessment and monitoring. World Heath Organization. 4 Dec 2008  http://www.who.int/immunization_monitoring/diseases/pertussis/en/index.html

 

     7. "Pertussis Outbreak Among Adults at an Oil Refinery --- Illinois, August--October 2002."  MMWR. 10 January 2003. CDC. 8 Dec 2008 http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5201a1.htm

.

     8. "Pathogenic Neisseria, Syphilis, and Vaccine Preventable Bacterial Diseases." Public Heath Agency of Canada. 1 March 2006. National Microbiology Laboratory. 8 Dec 2008

          http://www.nml-lnm.gc.ca/eb-be/NSVP-NSMBV-eng.htm

 

     9. "Statistics: Pertussis." 3 August 2007. Texas Department of State Health Services. 8 Dec 2008  http://www.dshs.state.tx.us/idcu/disease/pertussis/statistics/County/

 

    10. "Preventing Tetanus, Diphtheria, and Pertussis Among Adolescents: Use of Tetanus Toxoid, Reduced Diphtheria Toxoid and Acellular Pertussis Vaccines." MMWR. 24

          March 2006. CDC. 8 Dec 2008  http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5503a1.htm