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Rocky Mountain Spotted Fever and Typhus Fever
Published in James H. S. Gear, CRC Handbook of Viral and Rickettsial Hemorrhagic Fevers, 2019
The rickettsial diseases are characterized by fever, headache, malaise, myalgia, and a rash. The time of appearance and nature of the rash may make the diagnosis clear at the bedside. As a general rule, the exanthem is initially pink, macular, and fades on pressure. Within several days, in severe cases, the rash becomes fixed, fails to fade and develops hemorrhagic features, i.e., petechiae. These lesions may coalesce, particularly over pressure areas, such as the elbows, knees, hips, buttocks, etc., to form large ecchymotic bruises. Generally, the rash is first noted on the 4th to 6th days. It may be observed as early as the 1st day and as late as the 7th or 8th days. Also, occasionally, the rash may suddenly appear and progress rapidly from a few pink macules to diffuse petechiae which resemble the purpura of idiopathic thrombocytopenia. Usually, these are the more severely ill patients who may die or recover only after prolonged illness.
Pneumonitis In Rickettsial Infections
Published in Lourdes R. Laraya-Cuasay, Walter T. Hughes, Interstitial Lung Diseases in Children, 2019
Rickettsial infections are caused by fastidious, obligately intracellular bacteria which contain both DNA and RNA, multiply by binary fission, and are inhibited by antibiotics. Rickettsiae are primarily arthropod borne; i.e., they are spread by hematophagous invertebrates such as ticks, mites, lice, and fleas. Members of the Rickettsia genus appear negative on Gram stain and are divided into three serologic groups: spotted fever, typhus, and scrub typhus. The Q fever agent Coxiella burnetii is classified separately from the Rickettsia genus proper on the basis of several differences. These include its smaller size, Gram-positive staining properties, resistance to heat and dessication, probable respiratory mode of transmission, and absence of cross reactivity with Proteus antigens (Weil-Felix serology).
An Overview of Microbes Pathogenic for Humans
Published in Nancy Khardori, Bench to Bedside, 2018
Eric Lehrer, James Radike, Nancy Khardori
Rickettsia species are obligate intracellular pathogens that are transmitted by ticks. Rocky Mountain Spotted Fever (RMSF) is a serious but curable tick-borne illness. It is caused by Rickettsia rickettsii. RMSF has a wide clinical spectrum, from the mild to severe fulminant infections. In the early stages of the illness, most patients present with nonspecific signs and symptoms (fever, headache, malaise, myalgias, nausea), and a rash develops after several days. RMSF cases have been documented throughout North and South America. In the United States, it is most prevalent in the southeastern and south central states. Orientia tsutsugamushi (formerly known as Rickettsia tsutsugamushi) is the organism responsible for scrub typhus, the vector of which is the larval-stage trombiculid mite or chigger. Scrub typhus is endemic in many southeast Asian nations and portions of Australia that border the Indian Ocean. Scrub typhus can present either as a nonspecific febrile illness or with multisystem organ dysfunction. Additionally, given its ability to present as a hemorrhagic fever, scrub typhus should always be considered along with leptospirosis, malaria, and dengue fever in patients presenting with hemorrhagic fever.
Spotted fever diagnosis: Experience from a South Indian center
Published in Pathogens and Global Health, 2021
Elangovan D, Perumalla S, Gunasekaran K, Rose W, Verghese V p, Abhilash K Pp, Prakash Jaj, Dumler Js
Among these 48 spotted fever (SF) cases, 41 (84%) were children. Male (n = 28) to female (n = 21) ratio among these was 4:3. Rash appeared by the fifth day after fever onset in 45 (92%) of the 48 cases. Maculopapular rash was observed in 34 (70.8%) patients; while six (12.5%) had macular rash, purpuric or petechial rash (severe rash) was seen in 8 patients (16.7%). Rash on palms and soles was observed in 35 (71.4%), pedal edema in 19 (39.6%) and hepatomegaly in one (2.1%) case. Among the 48 patients, 43 received doxycycline and 5 received azithromycin, and all demonstrated defervescence of fever within 72 hours of initiation of therapy. Rickettsia-specific therapy (doxycycline or azithromycin) was initiated in 44 (90%) of the 48 patients before samples were sent for spotted fever diagnostic assays. None of our spotted fever cases had eschar and there were no fatalities.
The relevance of studying insect–nematode interactions for human disease
Published in Pathogens and Global Health, 2022
Zorada Swart, Tuan A. Duong, Brenda D. Wingfield, Alisa Postma, Bernard Slippers
The nematode species responsible for the majority of filariasis all rely on an intracellular bacterium for their development and reproduction [5,32]. The bacterial symbiont, Wolbachia, belongs to the order Rickettsiales – the same order containing Rickettsia species associated with tick-bite fever and other spotted fevers. The drugs used to treat rickettsia infections, especially doxycycline, successfully suppress filarial infections [56,57]. Unfortunately, a course of treatment with doxycycline lasts 6–8 weeks and cannot be used in pregnant women or children.
Prevalence of Spotted Fever Group Rickettsia in North-Eastern Poland
Published in Infectious Diseases, 2019
Karol Borawski, Justyna Dunaj, Piotr Czupryna, Sławomir Pancewicz, Renata Świerzbińska, Agnieszka Żebrowska, Anna Moniuszko-Malinowska
Our study confirms that Rickettsia spp. is present in the Central Europe regions, and potentially can be dangerous for humans. It is important to consider Spotted Fever Group Rickettsiosis in the differential diagnosis of fever after a tick bite.