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Invasive Haemophilus Influenzae Disease

Invasive H. influenzae disease is a bacterial infection causing serious illness in young children. The bacteria are spread by direct contact, oral contact or contact with contaminated objects. H. influenzae serotype b (Hib) was the most common cause of bacterial meningitis in young children in Canada before the introduction of vaccine in 1985. Between 1988 and 2004, the number of reported cases of Hib in children less than five years of age fell by almost 97%. The National Advisory Committee on Immunization (NACI) recommends immunization against Hib.

About Invasive Haemophilus influenzae Disease

Agent of disease

Invasive H. influenzae disease is caused by the bacterium Haemophilus influenzae. While some forms of the bacteria are encapsulated and cause invasive disease (e.g. types a, b, c, d, e, and f), while other forms of the bacteria are not encapsulated and generally cause milder disease (e.g. non-typeable).

Symptoms

H. influenzae can cause a variety of infections ranging from mild to severe. The most common infections are of the nose and throat and do not cause illness. Surface infections of the respiratory tract can causebut may result in pneumonia and bronchitis as well as ear, eye and sinus infections. Invasive H. influenzae disease is a severe form of infection that occurs when the bacterium gets into parts of the body where bacteria are not usually found, such as the bloodstream. This can result in serious conditions including meningitis, bacteremia, epiglottitis, and joint and bone infections. Symptoms of meningitis usually develop 2 to 4 days after infection and include the sudden onset of fever, changes in behaviour, severe headache, and a stiff neck and back. In infants, the soft part of the head (fontanelle) may bulge. Long-term effects of infections resulting in meningitis include permanent hearing loss, paralysis, seizures, brain damage and death.

Period of communicability

An infected person can transmit the infection as long as the bacteria are present in the body. With effective antibiotic treatment, a person becomes non-infectious within 24 to 48 hours.

How it is transmitted

The infection enters the body through the nose or mouth. Spread between people can occur through direct contact (e.g. coughing and sneezing), oral contact (e.g. kissing and sharing of drinks) and touching contaminated objects (e.g. sharing toys).

Worldwide distribution

H. influenzae type b infections are common throughout the world. In Canada, incidence rates have decreased since the introduction of vaccines in 1998, from 2.6 per 100,000 in 1988 to 0.3 per 100,000 in 2004.

Prevention and control

H. influenzae type b infections can be prevented by immunization. Immunization of all children is recommended by NACI at 2, 4, and 6 months of age, with a fourth dose at 18 months. For further information about the vaccine and its use in adolescents, adults, and special populations, please refer to the most recent version of the Canadian Immunization Guide.

Invasive Haemophilus influenzae Disease Epidemiology in Canada

As seen in Figure 1, since the introduction of Hib vaccines in Canada in 1988, the overall incidence of reported Hib has disease decreased by 94% from an average of 1.51 cases per 100,000 during 1981 to 1985 (average of 385 cases per year) to 0.09 cases per 100,000 from 2006 to 2010 (average of 31 cases per year). Between 2006 and 2010, average Hib incidence was greatest among infants less then one year old (2.07 cases per 100,000), followed by children aged one to four years (0.22 cases per 100,000) and adults 60 years and greater (0.14 cases per 100,000).

Invasive disease due to non-type b H. influenzae became nationally notifiable in 2007 and preliminary data suggest numbers of invasive non-b cases similar to that seen for Hib in the early 1990s. In 2010 and 2011, Hib made up only 12% of nationally reported H. influenzae cases on average. The average incidence of invasive non-b H. influenzae disease from 2010 to 2011 was 0.60 cases per 100,000 population (average 200 cases), with the highest incidence among less than one year olds (3.14) followed by adults 60 years of age and older (1.76) and one to four year olds (1.50).

Figure 1. Reported cases* and incidence rate (per 100,000 population) of invasive disease due to Haemophilus influenza type b, and year of vaccine introduction.

Figure 1. Reported cases* and incidence rate (per 100,000 population) of invasive disease due to Haemophilus influenza type b, and year of vaccine introduction.

*Case data obtained from the Canadian Notifiable Disease Surveillance System. Population data obtained from Statistics Canada July 1st annual estimates. Data for 2009 to 2011 are preliminary. Only Hib meningitis was reportable from 1979 to 1985. After this, all invasive disease caused by Hib became reportable.
‡PRP-D represent Hib conjugate vaccine containing purified polyribosylribitol phosphate capsular polysaccharide of Hib covalently bound to diphtheria protein.

Figure 1 - Text Equivalent

Invasive Haemophilus influenzae Disease Surveillance in Canada

In Canada, surveillance data on invasive disease caused by H. influenzae are collected through three systems at the federal level: the Canadian Notifiable Disease Surveillance System (CNDSS), the International Circumpolar Surveillance (ICS) System, and the Immunization Monitoring Program, ACTive (IMPACT). From 1979 to 1985, national data on all confirmed cases of H. influenzae type b meningitis was nationally reportable. Beginning in 1986, all invasive forms of H. influenzae type b disease were nationally notifiable. In 2010, CNDSS also began collecting national data on confirmed cases of invasive H. influenzae non-type b disease. Enhanced data from participating northern regions has been actively collected through ICS since 2000. Finally, enhanced data on confirmed cases of invasive H. influenzae type b disease was actively collected from participating paediatric tertiary care hospitals through IMPACT from 2000 to 2007. Since 2007, all types of invasive H. influenzae disease have been actively collected through IMPACT.

Invasive Haemophilus influenzae Disease Data

Tables 1 and 2 contain recent data on the number of reported cases and incidence of invasive H. influenzae serotype b disease in Canada from 2005 to 2011. Data for 2009 to 2011 are preliminary. Preliminary national data is currently available for H. influenzae non-type b disease only for 2010 and 2011 (tables 3 and 4). For further surveillance data, please see the Notifiable Diseases On-Line webpage as well as the Publications section below.

Table 1. Reported cases of invasive Haemophilus influenzae serotype b disease in Canada by year and age group, 2005 to 2009.
Year All Ages Less than 1 1 to 4 years 5 to 9 years 10 to 14 years 15 to 19 years 20 to 24 years 25 to 29 years 30 to 39 years 40 to 59 years 60 or Greater Age Unspecified

*Data obtained from the Canadian Notifiable Diseases Surveillance System.
†Based on preliminary data.

2005* 30 6 2 2 1 1 0 1 4 8 5 0
2006* 32 10 3 1 0 0 1 1 7 2 7 0
2007* 27 6 2 0 0 1 1 0 4 5 8 0
2008* 2 1 0 0 0 0 0 0 0 0 1 0
2009 29 10 2 1 2 0 0 0 2 4 7 1
2010 20 1 2 1 0 0 0 0 1 3 12 0
2011 38 6 3 0 0 1 1 1 2 12 12 0
Table 2. Reported incidence per 100,000 population of invasive Haemophilus influenzae serotype b disease in Canada by year and age group, 2005 to 2009
Year All Ages Less than 1 1 to 4 years 5 to 9 years 10 to 14 years 15 to 19 years 20 to 24 years 25 to 29 years 30 to 39 years 40 to 59 years 60 or Greater

*Data obtained from the Canadian Notifiable Diseases Surveillance System.
†Based on preliminary data.

2005* 0.09 1.77 0.15 0.11 0.05 0.05 0.00 0.05 0.09 0.08 0.09
2006* 0.10 2.86 0.22 0.05 0.00 0.00 0.04 0.05 0.16 0.02 0.12
2007* 0.08 1.67 0.14 0.00 0.00 0.04 0.04 0.00 0.09 0.05 0.13
2008* 0.14 2.95 0.49 0.11 0.00 0.00 0.13 0.09 0.04 0.09 0.14
2009 0.09 2.63 0.14 0.06 0.10 0.00 0.00 0.00 0.04 0.04 0.11
2010 0.06 0.26 0.13 0.06 0.00 0.00 0.00 0.00 0.02 0.03 0.18
2011 0.11 1.56 0.20 0.00 0.00 0.05 0.04 0.04 0.04 0.12 0.17
Table 3. Reported cases of invasive Haemophilus influenzae non-serotype b disease in Canada by year and age group, 2005 to 2009.
Year All Ages Less than 1 1 to 4 years 5 to 9 years 10 to 14 years 15 to 19 years 20 to 24 years 25 to 29 years 30 to 39 years 40 to 59 years 60 or Greater Age Unspecified

†Based on preliminary data. National data does not contain data for Ontario and Nova Scotia as it is not currently available.

2010 177 12 24 5 2 1 2 5 9 34 83 0
2011 223 21 12 6 3 1 3 7 17 41 112 0
Table 4. Reported incidence per 100,000 population of invasive Haemophilus influenzae non-serotype b disease in Canada by year and age group, 2005 to 2009.
Year All Ages Less than 1 1 to 4 years 5 to 9 years 10 to 14 years 15 to 19 years 20 to 24 years 25 to 29 years 30 to 39 years 40 to 59 years 60 or Greater

†Based on preliminary data. National data does not contain data for Ontario and Nova Scotia as it is not currently available.

2010 0.60 3.14 1.50 0.25 0.10 0.05 0.10 0.23 0.17 0.47 1.76
2011 0.75 5.54 0.76 0.30 0.15 0.05 0.15 0.33 0.33 0.55 2.34

Invasive Haemophilus influenzae Disease Resources

Case Definitions

Publications

Guidelines and Recommendations