Melioidosis
Melioidosis is an acute infectious disease, also known as Whitmore’s disease, occurring in the form of sepsis with the formation of multiple abscesses in various organs or as relatively benign pulmonary forms.
Etiology
The cause of the disease is Burkholderia pseudomallei /Whitmore’s bacillus/. It is a gram-negative, bipolar colored bacterium with a length of 2-6 microns and a width of 0.5-1 microns.
The aerobic infectious organism has flagella, is motile and grows readily in a nutrient medium. The causative agent of melioidosis is stored in the external environment for a long time.
In a moist environment it survives up to 30 days, in rotting matter – 24 days, and in water – up to a month or more. It dies when heated and under the action of disinfectants.
There are 2 antigenic types of the causative agent – type 1 /Asian/, widespread everywhere, including Australia, and type 2 /Australian/, predominant in Australia.
The pathogenicity of these types does not differ significantly. Whitmore’s bacillus is sensitive to chloramphenicol, tetracycline, camamycin and to some sulfonamide preparations.
Epidemiology
Whitmore’s disease is endemic to countries in Southeast Asia and northern Australia, where it occurs in humans and animals. It also observes in the neighboring countries of this region.
In European countries and the USA, cases of this infectious disease are rather an exception.
In endemic areas of Whitmore disease, the main reservoir of the bacillus causing the disease is soil and water contaminated with excrement from infected animals.
Pathogenesis
Doors of infection are small lesions of the skin or mucous membranes of the organs of the digestive system or respiratory tract. Whitmore’s lymphogenic bacillus reaches the nearby lymph nodes, where it multiplies, sometimes with the formation of a purulent focus.
In septic patients with Whitmore’s disease, the infectious organism penetrates the blood and hematogenously spreads to various organs and systems, forming numerous secondary foci with caseous decay and abscesses.
Most of the infectious foci develop in the lungs, and single abscesses are also formed in other organs.
In the subacute course of the infectious disease, the lesions in the lungs are characterized by large sizes, and secondary infectious foci are formed in all organs and tissues – skin, subcutaneous tissue, liver, kidneys, in the bones, in the meninges, in the main brain and in the lymph nodes.
Septic course of the infectious disease is observed in immunocompromised people. With good reactivity of the macroorganism, relatively benign lung abscesses occur more often, in which inflammatory changes and abscesses develop only and only in the lungs.
After passing Whitmore’s disease, antibodies are formed in the blood and cases of re-development of the disease have not been described.
Symptoms and course
The incubation period is a total of 2-3 days – according to laboratory data, from infection through damaged skin to the development of the disease. The main clinical forms are:
1. Septic /acute, subacute, chronic/;
2. Pulmonary – infiltrative, abscessing;
3. Recurrent;
4. Latent;
Treatment of melioidosis
The most effective treatment for all forms of melioidosis is the antibiotic chloramphenicol. Treatment is carried out with large doses – 3-4 daily. The duration of the course is several weeks. Lowering the dose and reducing the duration of treatment can lead to the occurrence of relapses.
Prevention
Whitmore’s disease is prevented by carrying out general hygiene measures in the areas where this disease is endemic, the purpose of which is to prevent Whitmore’s bacillus from entering the body – heat treatment of food and water, timely treatment of wounds, prohibition of bathing in reservoirs with stagnant water.
