Overview
Endemic typhus is an acute infectious disease caused by the transmission of Rickettsia muridii through rat fleas. It is also known as flea-borne typhus or murine typhus. The disease is globally circulating, and its symptoms are mainly fever with headache and rash, and it is a natural epidemic disease.
Causes
The main cause of the disease is the entry of Rickettsia muridarum from rat fleas into the human body through broken skin surfaces, leading to infection with Rickettsia muridarum, which causes endemic typhus in humans.
Symptoms
The incubation period is 6 to 16 days, mostly 12 days. A few patients have 1 to 2 days of prodromal symptoms such as fatigue, poor appetite and headache.
1. Fever
The temperature is about 39℃, which is auditory fever or flaccid fever, and reaches the peak in about 1 week, accompanied by headache, generalized pain and conjunctival congestion, and the fever lasts for 9～14 days, mostly subsides gradually.
2. Rash
Most of the patients have skin rash, mostly on the 4th to 7th day of illness, the rash is first seen on the chest and abdomen, and then spreads to the back, shoulders and limbs within 24 hours. The face, neck, palms and soles of the feet usually have no rash. Rash pattern is mostly congestive maculopapular rash, the size varies, the edge of the uneven, the beginning of the pink maculopapular rash, followed by dark red papules, lasts for 7 to 10 days to fade, generally do not leave traces.
3. Other
Neurological symptoms are mild, mostly dizziness, headache, and rarely consciousness disorder. The heart muscle is rarely involved, and bradycardia may occasionally occur. Cough is seen in half of the cases, occasional rales are heard at the base of the lungs, and some patients complain of sore throat and chest pain. 50% of the patients have splenomegaly.
Examination
1. Serologic examination
(1) OX19 is positive in exo-Fibre reaction. The patient’s serum can agglutinate with OX19 strain of Aspergillus, which is more sensitive, but the specificity is poor, so it can not be used to differentiate from epidemic typhus.
(2) Antibody test: Using Rickettsia morbillii antigen, indirect immunofluorescence test, complement binding test, etc. to detect its antibody, which has high sensitivity and specificity.
2. Pathogen isolation
Early blood inoculation of male guinea pigs in the abdominal cavity, guinea pigs, in addition to fever, scrotum highly edematous, testes obviously swollen, sphincter exudate examination can be seen in the cytoplasm of the swollen cells have a large number of rickettsiae. Rickettsia moresi was isolated from blood specimens during the febrile period, or polymerase chain reaction was used to detect Rickettsia moresi-specific deoxyribonucleic acid (DNA).
Diagnosis.
The diagnosis is not difficult to confirm in conjunction with laboratory tests in anyone who lives in an environment where rats are present or where the disease occurs, and who has a clinical picture of fever, rash, and a normal or mildly decreased total white blood cell count. The isolation of Rickettsia morganii or the detection of its nucleic acid are conclusive diagnosis.
Differential diagnosis
The disease must often be differentiated from epidemic typhus, endemic scrub typhus, typhoid fever, paratyphoid fever, renal syndrome hemorrhagic fever, leptospirosis, certain viral infections, and drug rashes. Pathogen isolation is required to differentiate the two typhus species. Typhoid fever and typhus have similar clinical manifestations, but patients with typhoid fever have an unremarkable headache, a delayed and less numerous rash, a positive Fickian reaction, and cultures of S. typhi. Leptospirosis often has no rash, but gastrocnemius muscle tenderness and lymph node enlargement are obvious, and it is not difficult to differentiate by applying serologic test and examination of leptospirosis. Drug rash has a history of drug use, itchy rash, and negative serologic tests.
Complications
Bronchitis is the most common, bronchopneumonia, thrombosis and embolic phlebitis, renal failure and respiratory failure are less common.
Treatment
1. Nursing care according to the general nursing routine of infectious diseases.
2. Pay attention to replenish water, electrolytes and vitamins.
3. Physical cooling is the mainstay for high fever, and small doses of antipyretic and analgesic drugs can be given if necessary. Adrenocorticotropic hormone can be given to those with severe symptoms of toxemia. When there is a tendency of hypovolemia or shock, it should be treated as infectious shock.
4. Doxycycline, minocycline and chloramphenicol are effective for this disease.