Pertussis or Whooping Cough - Research Paper Example

WHOOPING COUGH (PERTUSSIS) Whooping cough is a highly contagious disease, which is transmitted through air. It is highly communicable and nearly 90% of the susceptible individuals develop the disease. (Brenner et. al, 2005). Whooping Cough or Pertussis is caused by the bacteria, Bordetella pertussis. It belongs to the genus Bordetella in the family Alcaligenaceae. Pertussis is an acute respiratory infection marked by paroxysms of coughing. (Baron, 1996). It is named after the “whoop” sound produced by the children when they try to breathe during a heavy coughing spell. There are two types of pertussis: severe and mild. Severe pertussis occurs in the infants and young children. Severe pertussis is more complicated and may lead even to death, whereas, mild pertussis is hard to diagnose and it is mostly misunderstood for common cold. Bordetella pertussis was first isolated in pure culture in 1906 by Bordet and Gengou. B.pertussis is a small, gram –negative, aerobic coccobacillus of 0.8 μm by 0.4 μm. (Finger & von Koenig, 1996). It is arranged singly or in small groups. They also have pili-like filaments and are non-motile. B.pertussis is the most fastidious bacteria. It is transmitted from person – to – person through aerosolized droplets. (Baron, 1996) Figure 1 : Bordetella pertussis, the agent of pertussis or whooping cough. Gram stain. (CDC) (Todar, 2004) Pathogenicity B.pertussis causes respiratory tract infection in humans and warm blooded animals (Brenner et. al, 2005). The incubation period of this bacterium is 7-10 days. The bacterial cells “colonize only the ciliated cells of the respiratory mucosa.” (“Bacteria Genomes”). After the onset of the infection, the cells colonize in the mucosal membrane of the respiratory tract. The attachment of the B.pertussis occurs with the help of a pertussis toxin produced by the bacterium. The filaments those are present in the bacteria acts as a bridge between the bacterium and the ciliary receptor. Figure 2. Colonization of tracheal epithelial cells by Bordetella pertussis  (Todar, 2004) This pertussis toxin is highly toxic and has a number of virulent factors. The adjuvant effect of pertussis toxin on the human body results in lymphocytosis and hypoglycemia within 3 hours in the ciliated epithelial cells and also causes ciliostasis. The adenylate cyclase toxin and tracheal cytotoxin combines with pertussis toxin to cause ciliostasis. The same toxins inhibit the phagocytic activities of the host. The phagocytic activities include chemo taxis, engulfment, the oxidative burst, and bactericidal killing. The adenylate cyclase is a hemolysin that causes lysis of the red blood cells. The tracheal cytotoxin stops the beating mechanism of the ciliated cells. This toxin then kills the ciliated cells and extrudes it from the mucosa. It also stimulates the release of the Interleukin – I, thus causing fever. (Baron, 1996 & Todar, 2004) Signs and Symptoms The first stage symptoms of pertussis are cough, low –grade fever, running nose, sneezing, etc. After 7 – 10 days, the nasal discharge gets thickened and the cough also gets severe. This leads to severe upper respiratory congestion in infants. This is the second stage. It lasts for 1-2 weeks. The third stage is the more complicated stage. The coughing increases very heavily that the child will cough more than 5 times during a single respiration and have a sudden intake of air, causing a whooping sound. The sound is caused due to the narrowed glottis. At this stage vomiting, weight loss, tongue protruding, eyes bulging are most common. Pneumonia, the serious complication of pertussis, results in the 90% of the deaths in children under the age of 3. The infection of the bacterium causes substantial immunity. This substantial immunity lasts for many years. The second infections are more frequent in adults and are usually not severe. The infants and children are highly prone to the lethality of this disease. The children who are suffering from whooping cough are prone to pneumonia. This complication even leads to pertussis – related deaths among the infants. (Baron, 1996) Treatment The diagnosis of the bacterium is done by the following ways: (Baron, 1996). 1. Identification of the symptoms. 2. Physical examination. 3. The culture testing of bacterium from the nasopharyngeal swabs or nasopharyngeal secretions. 4. Direct fluorescent antibody (DFA) testing of the nasopharyngeal secretions. Erythromycin is the only antibiotic that is found to be effective on the bacterium. Administration of Erythromycin during the early stage of the disease will eliminate B.pertussis from the respiratory tract with in a few days. But at later stages it does not prove to be effective. Erythromycin when given at the second stage will prevent the infant from the paroxysmal stage. Hospitalization of the individual for a minimum of 3 months is required to treat the disease. Secretions from the upper respiratory tract and upper nose must be removed by suction for the infants. Oxygen, hydration and nutrition must be provided to the infants during the course of treatment. The whooping cough vaccine was developed in 1950. After the development of the vaccine it became an uncommon disease in developed countries. The whooping cough vaccine is administered to infants and children at 2, 4,6,12 and 15 months and 4-6 years of age respectively as Merthiolate - killed bacterial suspension of DTaP vaccine. The DTaP vaccine is also called as triple antigen and it is the vaccine for 3 diseases, namely Diphtheria, Tetanus and Whooping cough. The DTaP vaccine is approved by FDA. The whole vaccine developed for pertussis had some side effects. Hence a new acellular vaccine was developed from the purified components of B.pertussis. The new acellular vaccine had lesser side effects than the whole cell vaccine. This vaccine is approved for children less than seven years of age. (Todar, 2004). Whooping cough was a common and dangerous disease in the first half of the 20th century, as it killed many thousands of children every year. After the implementation of the widespread vaccination scheme, a sizable decrease in the incidence of the disease and the associated mortality rate was reported. Infants’ and children are highly susceptible to this disease, as B.pertussis can make dangerous impacts on infants less than 6 months. So, proper vaccination should be done for children at regular intervals. REFERENCES: “Bacteria Genomes - BORTEDELLA PERTUSSIS.’” European Bioinformatics Institute. Retrieved from: http://www.ebi.ac.uk/2can/genomes/bacteria/Bordetella_pertussis.html Brenner, D, Bergey, D H., Garrity, G M and Krieg, N R. (2005). Bergey's Manual of systematic bacteriology. Springer. Baron, S. (1996). Medical Microbiology. 4th edition. Addison-Wesley Publishing Company. Finger, H & von Koenig, C. H. W. (1996). Bordetella. University of Texas Medical Branch. Retrieved from: http://www.ncbi.nlm.nih.gov/books/NBK7813/ Todar, K. (2004). Online Text book of Bacteriology. Madison: University of Wisconsin. Read More