Haemophilus influenzae is a rod shaped, Gram negative bacteria, first described Richard Pfeifer in 1892 as a result of an influenza pandemic. While later discovered to not be the cause of influenza, Haemophilus influenza is still responsible for a number of diseases, including types of pneumonia and meningitis. Interest in this bacterium has led to it being the first organism to have its entire genome mapped.
While most strains of Haemophilus influenza do not cause illness in humans, pathogenic effects become apparent when the immune system of a host becomes weakened due to other factors such as viral infection or chronic illness. Disease caused by this bacterium has been largely eradicated or become easily treatable in developed countries, underdeveloped countries still suffer many cases of lower respiratory infections in infants because the vaccine is not widely available. It can also be the cause of ear infections, sinusitis, eye infections and pneumonia in children.
Diagnosis of disease resulting from the bacteria is most frequently done through a bacterial culture examination. It is important to note however, that instances of the bacteria in a host’s nasal cavity or saliva do not necessarily indicate infection, as disease free individuals carry the bacteria here. A positive sample taken from spinal fluid or blood is required to determine true infection. Very particular conditions are needed to grow Haemophilus influenza in culture, and as such many underdeveloped countries have not been able to isolate the bacteria.
Treatment can be difficult, especially in cases of misdiagnosis. Some strains of Haemophilus influenzae have been able to become penicillin resistant, therefore requiring alternate antibiotics to combat. Since the 1990s however, a vaccine has been available. Presently, the World Health Organization recommends a combination vaccine, including vaccines for tetanus, diphtheria, pertussis, hepatitis B, and Haemophilus influenzae infection. According to some sources, over 90% of individuals in developed countries have received the vaccination for Haemophilus influenzae.
As stated previously, this bacterium was the first organism to have its genome mapped in its entirety. The team chose this organism because of extensively collected information on its DNA previously. The mapping was complete in 1995 and published in several publications at the time. The leader of the team, Hamilton O. Smith, is a leader in the field of genomics, and has since been involved in the mapping of other genomes.