Recent developments in pertussis

Botulinum Toxin A: A Novel Adjunct Treatment for Debilitating Habit Cough in Children

Vocal fold injection with botulinum toxin type A (BTX-A) may be used as an adjunct treatment for habit cough in children. We conducted a retrospective review of 3 cases involving children aged 11 to 13 years with habit cough treated with vocal fold injection of BTX-A. Injections of BTX-A to the thyroarytenoid muscles were effective in breaking the cough cycle in all 3 children. Their coughs recurred but were controlled with 4 to 8 sessions of behavioral therapy. Behavioral therapy remains the first-line treatment, but BTX-A may be a useful complement to behavioral therapy in patients who fail standard treatments or in those with severe cough who have limited or delayed access to mental health professionals. This is the first report, to our knowledge, on the use of BTX-A in the treatment of a habit cough.

Microbiological aspects of bacterial lower respiratory tract illness in children: atypical pathogens

'Atypical' lower respiratory tract pathogens often cause a distinct identifiable syndrome in adults, but in children the clinical presentation of atypical, typical and viral pneumonia is less well differentiated. Specific microbiological investigations are usually required, but an understanding of their strengths and weaknesses is necessary to make interpretation possible. This review examines clinical presentation, microbiology and current evidence surrounding diagnostic techniques for Mycoplasma pneumoniae, Chlamydophila pneumoniae, Chlamydophila psittaci, Bordetella pertussis and Legionella species. Applying an understanding of the investigations to the diagnosis of pneumonia in children may lead to more appropriate patient management by ensuring that they clarify rather than further obscure the diagnosis.

Lung response to Bordetella pertussis infection in mice identified by gene-expression profiling

Host genetics determines the course of Bordetella pertussis infection in mice. Previously, we found four loci, Tlr4 and three novel loci, designated Bps 1–3, that are involved in the control of B. pertussis infection. The purpose of the present study was to identify candidate genes that could explain genetic differences in the course of B. pertussis infection, assuming that such genes are differentially regulated upon infection. We, therefore, studied the course of mRNA expression in the lungs after B. pertussis infection. Of the 22,000 genes investigated, 1,841 were significantly differentially expressed with 1,182 genes upregulated and 659 genes downregulated. Upregulated genes were involved in immune-related processes, such as the acute-phase response, antigen presentation, cytokine production, inflammation, and apoptosis, while downregulated genes were mainly involved in nonimmune processes, such as development and muscle contraction. Pathway analysis revealed the involvement of granulocyte function, toll-like receptor signaling pathway, and apoptosis. Nine of the differentially expressed genes were located in Bps-1, 13 were located in Bps-2, and 62 were located in Bps-3. We conclude that B. pertussis infection induces a wide and complex response, which appears to be partly specific for B. pertussis and partly nonspecific. We envisage that these data will be helpful in identifying polymorphic genes that affect the susceptibility and course of B. pertussis infection in humans.

The management of acute bronchitis in children

Acute bronchitis is one of the most common infections reported in children under 5 years of age, and is a leading cause of hospitalisation. In general practice, confusion surrounds the clinical diagnosis of acute bronchitis, especially when distinguishing it from asthma. The microbiological causes are mostly known, but the contribution of each is much less clear, and they are non-specific in their clinical expression in individual cases. Viral pathogens, particularly respiratory syncytial virus and rhinoviruses are cited as the leading agents in the development of serious episodes, but other pathogens may also be important. This article covers a range of issues surrounding acute bronchitis, including epidemiology and pathogenesis, as well as the management, prevention and treatment of disease in children.

Prevention of pertussis: Recommendations derived from the second Global Pertussis Initiative roundtable meeting

The Global Pertussis Initiative (GPI) was established in 2001 to assess the global extent of the ongoing problem of pertussis and to evaluate and prioritize pertussis control strategies. Exchange of data, knowledge, and experience, facilitated by discussion and debate, resulted in the formulation, in 2002, of the following recommendation: all countries should consider expanding existing vaccination strategies to include adding pertussis booster doses to pre-school children (4-6 years old), to adolescents, and to those specific adults that have the highest risk of transmitting Bordetella pertussis infection to vulnerable infants. The GPI met again in 2005, where it reinforced its previous recommendation for universal adolescent immunization. Additionally, the GPI recommended implementation of the cocoon strategy (immunization of family members and close contacts of the newborn) in countries where it is economically feasible, and encouraged efforts toward global standardization of pertussis disease clinical definitions and diagnostics. Universal adult vaccination is a logical goal for the ultimate elimination of pertussis disease, but feasibility issues remain obstacles to implementation.

Pertussis in adolescents

Pertussis is a highly communicable respiratory infection caused by Bordetella pertussis. In spite of the widespread availability of effective vaccines and high levels of vaccination coverage, a significant resurgence in pertussis has been observed during the past 2 decades. The increase in reported cases is due in large part to infection in adolescents and adults, and waning immunity plays an important role. Pertussis in adolescents and adults often goes unrecognized because a persistent, uncharacteristic cough might be the only clinical presentation. Pneumonia is the most frequent complication. Culture and polymerase chain reaction are helpful in establishing the diagnosis if a specimen can be obtained early in the course of the illness. Serology is useful when the diagnosis is not suspected until a later stage. Treatment with a macrolide antibiotic is recommended for affected individuals, as well as for all household and other close contacts. Universal immunization is necessary for disease control. Immunization should begin in infancy and should continue with booster doses through adulthood. Two adolescent and adult formulations of acellular pertussis vaccine are licensed in North America and Europe. Both are combined with an adult formulation of diphtheria and tetanus toxoids. In the US, Adacel (Sanofi Pasteur, Toronto, Ontario, Canada) is licensed for use in individuals aged 11 to 64 y while Boostrix (GlaxoSmithKline Biologicals, Rixensart, Belgium) is licensed for use in individuals aged 10 to 18 y. These vaccines are safe, immunogenic, and well tolerated. Routine vaccination of adolescents and adults is required for optimal control of pertussis.

New combination vaccines still need a boost

Perspective on the paper by Kitchin et al (see page XXX)