Q fever

Q fever (synonym: Queensland fever, rickettsiosis Q, Central Asian fever, Termez fever) is an acute febrile illness rickettsioses etiology, often occurring with lung or as an asymptomatic infection recognized only serologically.
Etiology. The causative agent of q-fever - rickettsiae of Barneta - morphologically similar to Rickettsia of Prowazeki, differs only highly resistant in an external environment. Remain viable on clothes over 1 month; in the water more than 4 months, salted meat - 5 months, milk, cheese, yogurt, kefir, many days; withstands heat the milk to a temperature 90 degrees, but dies within 1 minutes boiling. In addition to the sick person, the causative agent was detected in many wild (88 species) and domestic animals and birds (72 species), of which a dominant role in the epidemiology has the cattle that produce rickettsiae with milk, urine, faeces, placenta and amniotic fluid.
Epidemiology. The presence of rickettsiae of Barneta in wild animals and birds, have different ticks can transmit the pathogen its offspring, says natural foci of infection. Infected Pets, apparently, occurs in natural foci further spread within the herd. Infected animals may take a chronic course, puffing on for years. Q fever can be a cause of albasti and miscarriages in cows, goats, sheep. Q fever is registered in the Central Asian republics, Kazakhstan and a number of regions of the RSFSR. The disease often occur in spring and summer. Ill Ku fever mainly people working in the meat, milk, wool-processing industry, in agricultural farms and drug infected raw dairy products. Human infection is possible in different ways. Alimentary way of infection associated with eating raw infected products, milk and its products. Aspiration of transmission occurs by inhalation of infected dust or air, often when working with wool, fur, leather infected animals, as well as when infected straw or hay. Contact transmission possible when caring for the sick cattle slaughter of diseased animals, assistance at childbirth, etc., vector-Borne transmission is through the bite of ticks is extremely rare. Contamination by airborne droplets when communicating with a person who has severe pulmonary form that is observed in very rare cases.
Pathogenesis. Infection by Rickettsia of Barneta people are highly sensitive, but clinically evident disease is not always the case. The occurrence of asymptomatic course q-fever depends on a number of factors, but the main role is played by a small dose of the pathogen. The course of disease depends on a condition of an organism and also from the infection mechanism. So, when the suction route of infection is clinically defined forms of the disease occur often, and when alimentary - rare. Asymptomatic forms, evidently due to repeated exposure to small doses of the agent through the use of pasteurized milk, pasteurization can remain active for only a small part of rickettsiae, that is the latent fractional immunization. Clinically evident disease leaves a lasting immunity for several years.
Pathological anatomy of q fever have been little studied. The lungs are determined bronchopneumonias lesions, often drain, surrounded by inflammatory infiltrate. In the spleen are marked acute hyperplasia pulp and hyperemia. In the brain there are perivasculitis and small hemorrhages around vessels, sometimes clots. Proven abundant accumulation of rickettsiae during pregnancy and highlights them in childbirth or abortion with the placenta, amniotic fluid and detachable generic ways.


Temperature curve patient Ku-fever (RSN - reaction of binding complement; OTP - negative)

The clinical picture of q-fever is characterized by a great variety of symptoms and has no unusual features. The incubation period is from 1 to 4 weeks. The illness usually begins suddenly, rarely gradually - with a little chills and fever in the evening. You may receive General malaise, feeling of weakness and headache. In 1-2 days the temperature reaches 39 - 40 and kept 7-14 days, declining political. Temperature curve may be incorrect or remitting type (Fig.).
Sometimes there are short-term recurrences of the disease. The rash is usually absent. There is often atypical pneumonia with infiltrates recognized mainly radiographically. Cardiovascular system suffers a little. From the nervous system marked by severe headaches, occasionally meningeal phenomenon. Spleen and liver are often increased. ROE slightly accelerated.
The disease is severe. The long period of convalescence, performance is recovering very slowly. Mortality in Ku-fever of about 1%.
Clinical diagnosis of q-fever difficult.
Laboratory diagnosis of q-fever is crucial and is ensured by setting the reaction of binding complement and agglutination reaction rickettsiae of Barneta. RAC becomes positive with 5-9-day illness, most expressed in 3-5 weeks and in low titers holds for several years. Titers of 1:10-1:20 regarded as diagnostic, but for the substantiation of the diagnosis requires a re-examination, in order to identify growth titer. The agglutination reaction becomes positive with the end of the first - beginning of the second week of illness, the maximum credits reaches for 3-5 weeks and in low titers maintained for a period of 3-6 months. Is used to diagnose skin allergic test. Allergen from rickettsiae of Barneta enter inside-skin in the area of the forearm in the dose of 0.1 ml of a positive result on the introduction of the allergen appear redness and small infiltration. Accounting lead in 24-48 hours. The reaction is detected on the first week of illness and is marked by several years. In recent years, for the diagnosis of q-fever used method of IgM antibodies that detect rickettsiae in blood of patients already on 4-6th day of illness.
Treatment. Assign biomitsin or terramycin 1-2 g / day fractional doses within 5-7 days, symptomatic and cardio-vascular equipment. To prevent relapse treatment continue at least 5-7 days. Chloramphenicol and tetracycline less effective. Patient q-fever provide bed rest, care and diet, regular for feverish patients. Special isolation of patients is not required.
Prevention. It is necessary to conduct health measures among farm animals - sources of infections and sanitary measures for the protection from diseases of the population and workers of animal husbandry. About each disease inform the epidemiologist and conduct epidemiologic study to identify the source of infection and ways of infection. For specific prophylaxis used live vaccine (see Vaccines).