The course of disease is different depending on the route of exposure. Mortality in untreated (before the antibiotic era) patients has been as high as 50% in the pneumoniac and typhoidal forms of the disease, which however account for less than 10% of cases. Spread
The most common way the disease is spread is via arthropod vectors. Ticks involved include Amblyomma, Dermacentor, Haemaphysalis, and Ixodes. Rodents, rabbits, and hares often serve as reservoir hosts, but waterborne infection accounts for 5 to 10% of all tularemia in the United States. Tularemia can also be transmitted by biting flies, particularly the deer fly Chrysops discalis. Individual flies can remain infectious for 14 days and ticks for over two years. Tularemia may also be spread by direct contact with contaminated animals or material, by ingestion of poorly cooked flesh of infected animals or contaminated water, or by inhalation of contaminated dust. Diagnosis
Pathology
In lymph node biopsies, the typical histopathologic pattern is characterized by geographic areas of necrosis with neutrophils and necrotizing granulomas. The pattern is non specific and similar to other infectious lymphadenopathies.The laboratorial isolation of F. tularensis requires special media such as buffered charcoal yeast extract agar. It cannot be isolated in the routine culture media because of the need for sulfhydryl group donors (such as cysteine). The microbiologist must be informed when tularemia is suspected not only to include the special media for appropriate isolation, but also to ensure that safety precautions are taken to avoid contamination of laboratory personnel.
Azelaic acid (AzA) is an organic compound with the formula HOOC(CH2)7COOH. This saturated dicarboxylic acid exists as a white powder. It is found in wheat, rye, and barley. It is a precursor to diverse industrial products including polymers and plasticizers, as well as being a component of a number of hair and skin conditioners. AzA inhibits tyrosinase. Production
Azelaic acid is industrially produced by the ozonolysis of oleic acid. The side product is nonanoic acid. It is produced naturally by Malassezia furfur (also known as Pityrosporum ovale), a yeast that lives on normal skin. The bacterial degradation of nonanoic acid gives azelaic acid. Biological function
In plants, azelaic acid serves as a "distress flare" involved in defense responses after infection. It serves as a signal that induces the accumulation of salicylic acid, an important component of a plants defensive response. Applications
Polymers and related materials
Esters of this dicarboxylic acid find applications in lubrication and plasticizers. In lubricant industries it is used as a thickening agent in lithium complex grease. With hexamethylenediamine, azelaic acid forms Nylon-6,9, which finds specialized uses as a plastic. Medical
Azelaic acid is used to treat mild to moderate acne, both comedonal acne and inflammatory acne. It belongs to a class of medication called dicarboxylic acids. It works by killing acne bacteria that infect skin pores. It also decreases the production of keratin, which is a natural substance that promotes the growth of acne bacteria. Azelaic acid is also used as a topical gel treatment for rosacea, due to its ability to reduce inflammation.