Scrub typhus

Overview scrub typhus (O. disease), also known as scrub typhus (scru b typhus), by Rickettsia tsutsugamushi caused by natural focal disease. Clinical features include sudden fever, bites Department eschar or ulcers, swollen lymph nodes and skin rash. Early in the year 313, China Men physician Pao described as "pass through bushes, the sand was a small red sand louse bites that occur rash, fever three days later, bites local crusted ulcers, " had a modern scrub typhus. However, it was not until 1948 in Guangzhou only isolated Rickettsia tsutsugamushi. Department of the Japanese Foreign earliest in 1810 first described the disease. 1927 Japanese scholars Ogata regulations - such as injecting blood of patients with testicular rabbits, 5-by-6's, scrotal swelling, lesser smear staining found Rickettsia body named to the East rickkettsiosis (Rickettsia orteintalis). 1931 known as the Rickettsia tsutsugamushi (Rickettsia fold). Pathogenic Rickettsia tsutsugamushi roughly double the ball or short rod, paired with more size and About 0.2 × 0.3 ~ ~ 0.5μm 1.5μm, parasitic in the cytoplasm. With Giemsa staining, cells were purple, blue cytoplasm of desalination, Rickettsia body near the nucleus of purple beside piles arranged. Patients with blood and other samples were cultured in chicken yolk sac, Hela cells can be isolated pathogens. Its very sensitive mice, which are often used for pathogen isolation. The strains of Rickettsia-specific antigen in serum - more, the adoption and the pilot, complement fixation test can be divided into five types : Karp, Gilliam, kato, Fan and Chon. Recently identified three new type of antigen, a total of eight have been found antigen type. Due to different regions and different strains of the antigen and virulence are differences, the mortality of the disease and was quite different. Rickettsia tsutsugamushi another with the Proteus with OXk common antigen components of the heat-resistant polysaccharide antigen, Clinical OXk Proteus used as antigen agglutination test for the diagnosis. But with the OX2, OX19 no aggregation. Heat-resistant pathogens is not cold, hypothermia can keep for long, -20 ° C to survive five weeks. Heating 56 ° C for 10 minutes shall be killed; the general disinfectant is extremely sensitive. Epidemiology of the disease is widely distributed across the Pacific, the Indian Ocean tropical and subtropical regions, but in Southeast Asia, Australia and the Far East Common. China mainly occurred in Zhejiang, Fujian, Taiwan, Guangdong, Yunnan, Sichuan, Guizhou, Jiangxi, Xinjiang, Tibet, and other provinces, autonomous regions, to coastal islands multiple. In recent years, Jiangsu, Shandong, Anhui, and in some areas there is a small pop or dissemination. (1) infection is a major source of rodent-borne source and storage of the host, such as ditch rats, Yellow-breasted rats, Rattus norvegicus, the vole. Hare, rabbits, poultry and certain species of birds can be infected with the disease. Mice infected more subclinical infection, but the preservation of Rickettsia intimate body for a long time, the infectious period of longer. Suffering from the disease, although blood Rickettsia body, but because of chigger bites human gill merely accidental phenomenon, So patients as a source of infection is largely meaningless. (2) transmission of chigger larvae of the disease media. Chigger various types of nearly 3,000, but can spread the disease mainly for Lane chigger, and chigger Red Lake High chigger. Their life cycle, including eggs, larvae, nymphs, pupae and adult. Camp parasitic larvae only need to suck life of the animal body fluids, and the rest were self-development of life. As the larvae life only bites an animal or person, rodents were infected by the Rickettsia The chigger larvae, In contemporary no chance for the spread, nymphs, pupae and adult development for spawning. Rickettsia-egg inspired by the next generation (2G) larvae, the larvae when 3G Biting animal or person, Rickettsia body with the saliva into the new host, it called generation transmission. (See figure). Chigger mite larvae spread scrub typhus crowd Map susceptibility of the disease are susceptible, but most of the patients were young adults. Immunity after infection period lasted only a few months, the longest 10 months. Which can only be given to the strains of pathogens Park immunity, it may again be infected by different strains of morbidity. (4) As the prevalence of rodents and insects Chigger the breeding and breeding climate and geographical factors, The disease prevalence is obviously seasonal and regional nature. North 10, in November high season, the South was 6-August peak of the epidemic, in November decreased, while Taiwan, Hainan, Yunnan by the warm climate, and the annual incidence can be. The disease mostly distributed in local occasionally pop. Chigger more life in the warm, damp, scrub edge, flat areas and wild corners of the strait.