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Typhus: diagnosis
Last reviewed: 23.04.2024
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Diagnosis of epidemic typhus is based on clinical epidemiological data, and the diagnosis is confirmed by laboratory tests. Significant importance is the presence of pediculosis, a characteristic type of patient, an intense headache in combination with insomnia, the appearance of rash on the 5th day of the disease, CNS damage, hepatolyenal syndrome.
Isolation of the pathogen, as a rule, is not carried out because of the complexity of cultivation of rickettsia, which is possible only in specially equipped laboratories with a high degree of protection.
The main diagnostic method (diagnostic standard) is serological: RSK, RIGA, RA, RNIF, ELISA. When carrying out the RSK, a titer of 1: 160 is considered diagnostic. A positive result in RNGA can be obtained from the 3rd-5th day of the disease, the diagnostic titer of this method is 1: 1000. RA in comparison with RNGA is less sensitive and has a diagnostic titer of 1: 160. In the RNIF and ELISA, specific IgM and IgG are determined. Reliability diagnosis of epidemic typhus is possible when several serological tests are used in parallel, usually RSK and RNGA.
PCR can be used to detect Riquettsia antigens.
Differential diagnosis of epidemic typhus
In the initial period, differential diagnosis of epidemic typhus is carried out with influenza, meningococcal infection, pneumonia, hemorrhagic fever, tick-borne encephalitis and other conditions with fever; during the height of the epidemic typhus differentiated from typhoid, measles, pseudotuberculosis, sepsis and other febrile diseases, accompanied by rashes.
The flu is characterized by a more acute onset, a sharp weakness, the presence of a constant sweating (typhoid fever in the vast majority of cases is dry), lack of puffiness of the face and amemia, as well as the symptom of Govorov-Godel. With flu, there is no rash, the spleen and liver are not enlarged. Headache is usually located in the forehead, superciliary arches and in the temporal areas, pain is typical when pressing on the eyeballs and when moving them. Intoxication is most pronounced in the first 3 days of the disease, from the second day the picture of tracheitis dominates.
Differential diagnosis of epidemic typhus and pneumonia is carried out taking into account the characteristics of breathing, physical data, cough, mild sweating, chest pain, lack of rash, Chiari-Avtsyn symptom, CNS lesion, X-ray data and blood picture.
Bacterial meningitis is differentiated from typhus due to the presence of a more pronounced meningeal syndrome (stiff neck muscles, positive symptoms of Kernig and Brudzinsky), as well as higher values of leukocytosis with neutrophilia. When analyzing the cerebrospinal fluid in patients with bacterial meningitis, cytosis and protein are detected, and for typhus - the phenomenon of meningism.
With hemorrhagic fever, especially with kidney syndrome, hyperemia of the face and conjunctiva is more pronounced, the rash has the character of ungainly punctate hemorrhages, which are more often detected on the lateral surfaces of the trunk and in the axillary regions. Typical: vomiting, hiccough, pain in the lower back and abdomen, typical thirst and oliguria. In these diseases, erythrocytosis is observed, normal or increased ESR, increased urea and creatinine in the blood, hematuria, proteinuria, cylindruria. The development of hemorrhagic phenomena occurs against the background of a decrease in temperature.
When typhoid fever is marked with pallor of the face, general adynamy, lethargy. Bradycardia with dicrotic pulse. The tongue is thickened, coated, with prints of teeth to the edges. Characteristic meteorism and rumbling in the right ileal region, as well as an increase in the liver and spleen at a later date. The rash is scanty roseous, appears later (no earlier than the 8th day of the disease) on the chest, abdomen and lateral surfaces of the trunk with subsequent podsypaniyami. In the blood they find leukopenia with eosinopenia, a stab-shift with relative lymphocytosis. Thrombocytopenia.
Differential diagnosis of epidemic typhus with tick-borne typhus occurring in the regions of Siberia and the Far East is based on symptoms characteristic of this disease: the presence of primary affect in the majority of patients at the site of the tick bite and on the development of regional lymphadenitis almost simultaneously with primary affect. The rose-papular rash is bright, spread all over the body. Characteristic of the appearance of rashes on the 2-4th day of the disease.
In ornithosis, it is important to have contact with birds in epidemics. The rash is only rosaolous, and it settles more often nestling on the trunk and extremities. In the blood - leukopenia, eosinopenia, relative lymphocytosis and a sharp increase in ESR. Interstitial pneumonia, confirmed by roentgenology, is typical.
Sepsis is distinguished from typhus due to the presence of septic foci and the entrance gate of the infection. For sepsis, a characteristic temperature is of a hectic nature. Sharp sweating and chills, hemorrhagic rashes on the skin, a significant increase in the spleen, clearly delineated hemorrhages of bright red on the eye mucosa, anemia, leukocytosis with neutrophilia, high ESR.
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