Relapsing fever aetiology and management

Relapsing fever aetiology and management

Relapsing fever aetiology and management

Relapsing fever is an acute infectious illness caused bySpirochaetes of the genus Borrelia. Borrelia recurrentis isthe cause of louse-borne relapsing fever, and a range ofother species cause the tick-borne variety.

Aetiology and transmission Borrelia are spiral organisms which can be identified inperipheral blood smears using Giemsa and Leishmanstains; they can also be readily identified using dark-groundmicroscopy and cultured on artifical media.Humans are the reservoir of infection of louse-bornerelapsing fever. The human body louse, Pediculushumanus, is the vector. Sudden mass migrations of peoplegrouped together in adverse conditions encourage thespread of lice and louse-borne diseases, relapsing fever andtyphus. Tick-borne relapsing fever is a sporadic zoonosis inhumans in areas where there is a cycle of transmissionbetween ticks and wild rodents. The disease has a worldwidedistribution, except for Australia and the Pacificregion.

Pathogenesis and pathology During the incubation period spirochaetes divide intravenously.Platelets are sequestered, intravascular coagulationoccurs, and a bleeding tendency results. After 4-5 daysof symptoms there is a crisis associated with massivephagocytosis of Borrelia, helped by opsonizing antibody.Following the crisis there is an afebrile period during whichnumbers of organisms expressing different surface antigensbuild up and symptoms recur. This can occur up tofive times.The spleen, liver, heart and brain are the main sites ofpathological lesions, which consist of macrophages surroundingand ingesting large numbers of organisms.

Clinical features After an incubation period that varies from 4 to 18 daysthe illness begins suddenly with rigors and a fever whichrises rapidly to 40C. Headache, joint pains, anorexia,malaise, nausea and vomiting are usual features, withmental confusion frequently present. Hepatosplenomegalyis common, with jaundice present in some patients. Apetechial rash, most prominent on the trunk, is seen.Bleeding from the nose, the respiratory tract or the gutmay occur, as may focal neurological signs.The first febrile period lasts about 5 days before spontaneousdefervescence. This follows a severe febrile paroxysmwith cold extremities, a rising pulse rate and bloodpressure, and tachypnoea. An afebrile period lasting about7 days recurs before the first relapse. Tick-borne disease ismilder than louse-borne disease. In both, death can occurduring the initial rigor or during defervescence.

Diagnosis Organisms can be found in Giemsa-stained peripheralblood smears. Dark-ground microscopy can be used todemonstrate the motile spirochaetes in a fresh blood smear.

Management Antibiotics kill spirochaetes readily. Tetracycline can beused in patients over 8 years old. Erythromycin can be usedin pregnant women and young children. Louse-bornerelapsing fever requires a single dose of 500 mg of eitherdrug. Tick-borne relapsing fever requires treatment for10 days.Supportive care is needed, particularly in patients withlouse-borne disease, as they can develop severe reactions,including Jarisch-Herxheimer, after being treated. Centralvenous pressure monitoring is essential if facilities are available.Hypoxia is corrected by giving oxygen continuously.Vitamin K is given if the prothrombin time is prolonged.

Prevention Delousing by washing with soap and water, followed bydusting with 10% DDT, is effective. Clothes should bewashed with soap in water at 55C to kill lice and nits (liceeggs), which are found in the seams of clothes. Lice cannotsurvive on a person who has two sets of clothes worn onalternate weeks.

POST COMMENT

Actinomyces diagnosis and management Madura foot diagnosis and management Nocardiosis clinical features and management Candida infections diagnosis and management Cryptococcosis clinical features and management Giardiasis etiology and management Cryptosporidiosis clinical features and management Why absence management is important African trypanosomiasis clinical features pathology and management Knowledge and Data Management Services An Asbestos Management Plan Can Save Lives How to Choose a Content Management System? Find Solution of your debt crisis with debt management