C. pilosellus and C. pipistrella primarily infest bats, while Haematosiphon inodora, a species of North America, primarily infests poultry. Evolution
Cimicidae, the ancestor of modern bed bugs, first emerged approximately 115 million years ago, more than 30 million years before bats—their previously presumed initial host—first appeared. From unknown ancestral hosts, a variety of different lineages evolved which specialized in either bats or birds. The common (C. lectularius) and tropical bed bug (C. hemipterus), split 40 million years before Homo evolution. Humans became hosts to bed bugs through host specialist extension (rather than switching) on three separate occasions. History
Bed bugs were first mentioned in ancient Greece as early as 400 BC, and later by Aristotle. Plinys Natural History, first published circa AD 77 in Rome, claimed bed bugs had medicinal value in treating ailments such as snake bites and ear infections. Belief in the medicinal use of bed bugs persisted until at least the 18th century, when Guettard recommended their use in the treatment of hysteria.Bed bugs were also mentioned in Germany in the 11th century, in France in the 13th century, and in England in 1583, though they remained rare in England until 1670. Some in the 18th century believed bed bugs had been brought to London with supplies of wood to rebuild the city after the Great Fire of London (1666).
An example might be a close contact of a patient known to have a fully sensitive strain of tuberculosis: in this case, it is acceptable to use 2HRZ/4HR (omitting EMB and STM) in the expectation that their strain will be INH susceptible also. Indeed, this was previously the recommended standard regimen in many countries until the early 1990s, when isoniazid-resistance rates increased. TB involving the brain or spinal cord (meningitis, encephalitis, etc.) is currently treated with 2HREZ/10HR (12 months of treatment in total), but there is no evidence to say that this is superior to 2HREZ/4HR. There is no difference in relapse rates amongst those who are treated with 6 months or longer period of time. However, more well-designed studies are needed to answer this question. Regimens omitting isoniazid
Isoniazid resistance accounts 6.9% of isolates in the UK (2010). Worldwide, it is the most common type of resistance encountered, hence the current recommendation of using HREZ at the beginning of treatment until sensitivities are known. It is useful to know of current reported outbreaks (like the current outbreak of INH-resistant TB in London). If patients are discovered to be infected with an isoniazid-resistant strain of TB having completed 2 months of HREZ, then they should be changed to RE for a further 10 months, and the same thing if the patient is intolerant to isoniazid (although 2REZ/7RE may be acceptable if the patient is well supervised). The US recommendation is 6RZE with the option of adding a quinolone such as moxifloxacin.