Sub-acute neuropathy in patients with African tick bite fever

Japanese spotted fever complicated by acute sensorineural hearing loss

Japanese spotted fever is an emerging rickettsiosis caused by Rickettsia japonica and is characterized by high fever, rash, and eschar formation. Other symptoms are often vague and nonspecific and include headaches, nausea, vomiting, and myalgia. We present a case of a 46-year-old woman with Japanese spotted fever, complicated by transient bilateral sensorineural hearing loss and presenting cutaneous IgM/IgG immune complex vasculitis. The patient was admitted with a history of several days of high fever, generalized skin erythema, and hearing impairment. Laboratory findings revealed thrombocytopenia and elevated liver enzyme and C-reactive protein levels. Pure-tone audiometry revealed bilateral sensorineural hearing loss, and a skin biopsy revealed leukocytoclastic vasculitis with deposition of C3 and IgM on the vessel walls. Under the tentative diagnosis of rickettsiosis, scrub typhus, or Japanese spotted fever, the patient was treated with minocycline, and her symptoms improved within approximately 10 days. A definitive diagnosis was made on the basis of a serological test showing increased antibody levels against Rickettsia japonica. Japanese spotted fever can cause transient sensorineural hearing loss, a rare complication that presents with cutaneous IgM/IgG immune complex vasculitis.

Clinical, epidemiological, and laboratory features of Rickettsia africae infection, African tick-bite fever: A systematic review

African tick-bite fever (ATBF), caused by Rickettsia africae, is the main tick-borne rickettsiosis and the second most frequent cause of fever after malaria in travelers returning from sub-Saharan Africa. General descriptions on ATBF were made in the first two decades after recognized as a new infectious entity, and since then, many authors have contributed to the knowledge of the disease by reporting clinical cases in scientific literature. We developed a systematic review that evaluated all available evidence in the literature regarding clinical, epidemiological, and laboratory features of confirmed R. africae rickettsiosis cases. We followed the recommendations made by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guide. A total of 48 scientific publications (108 confirmed cases) were analyzed in order to extract data for developing this review. Overall, our results show that R. africae rickettsiosis is more frequent in males in the age group of 18-64 years, more than 80% of the cases occurred in European travelers, South Africa was the country where most infections were acquired, and almost 40% of cases occurred in clusters. Clinically, more than 80% of the cases had fever and eschar (55% developed multiple eschars), rash was present in less than the half of cases, and lymphangitis was not a common sign (11%). Headache, myalgia and regional lymphadenopathy were predominant nonspecific clinical manifestation (mean of 60%, 49% and 51%, respectively). Our results show that at least 70% of R. africae cases had altered laboratory parameters, most often showing an increase in transaminases and C-reactive protein. Tetracycline-class antibiotics, as monotherapy, were used in most (>90%) of the patients. Overall, only 4% of cases had complications, 12% required hospitalization, and there was a 100% rate of clinical recovery.

Rickettsial infections of the central nervous system

As a result of migrations and globalization, people may face a possible increase in the incidence of central nervous system rickettsial infections (CNS R). These diseases, caused by Rickettsia species and transmitted to humans by arthropod bites, are putatively lethal. However, the diagnosis of CNS R is challenging and often delayed due to their nonspecific clinical presentation and the strict intracellular nature of rickettsiae. Furthermore, transfer of rickettsiae to the brain parenchyma is not yet understood. The aim of this review is to analyze and summarize the features and correlated findings of CNS R in order to focus attention on these intriguing but frequently neglected illnesses. We also incorporated data on CNS infections caused by Rickettsia-related microorganisms.

African Tick Bite Fever Treated Successfully With Rifampin in a Patient With Doxycycline Intolerance

African tick bite fever is the most commonly encountered travel-associated rickettsiosis, occurring in as many as 5% of travelers returning from rural subequatorial Africa. This case report illustrates that rifampin represents an effective alternative to doxycycline for treatment of African tick bite fever in some selective situations.

A Tale of Black Eschar in a Returning Traveller

BACKGROUND

African tick-bite fever is an increasingly common cause for fever in the returning traveller. It needs to be considered in the febrile returning traveller with a characteristic rash: a black eschar.

CASE REPORT

We describe a 51-year-old man returning from South Africa who presented to our emergency department with fever, headache, myalgia, and chills. On careful history and skin examination, a black eschar was found on the patient's left lateral shoulder, pointing toward a diagnosis of African tick-bite fever. The patient was treated with doxycycline and rapidly improved. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: In the emergency department, the diagnosis of African tick-bite fever is often overlooked in the pursuit of ruling out other travel-related illnesses, such as malaria. A thorough history, a complete physical examination, and a high level of suspicion are essential to the timely diagnosis and treatment of African tick-bite fever in the returning traveller.

Fever and Multiple Eschars After an African Safari: Report of Three Cases

African tick-bite fever (ATBF), a tickborne disease endemic in rural areas of sub-Saharan Africa and the West Indies caused by Rickettsia africae, has been recognized as an emerging health problem in recent years. ATBF has been reported as the second most commonly documented etiology of fever, after malaria, in travelers who return ill from sub-Saharan Africa. Most cases reported in the literature occurred in middle-aged adults, so the incidence of ATBF in children is unclear. We report a cluster of three cases of ATBF that occurred in children ages 7 to 16 years after returning from a game-hunting safari in South Africa.

High prevalence of Rickettsia africae variants in Amblyomma variegatum ticks from domestic mammals in rural western Kenya: implications for human health

Tick-borne spotted fever group (SFG) rickettsioses are emerging human diseases caused by obligate intracellular Gram-negative bacteria of the genus Rickettsia. Despite being important causes of systemic febrile illnesses in travelers returning from sub-Saharan Africa, little is known about the reservoir hosts of these pathogens. We conducted surveys for rickettsiae in domestic animals and ticks in a rural setting in western Kenya. Of the 100 serum specimens tested from each species of domestic ruminant 43% of goats, 23% of sheep, and 1% of cattle had immunoglobulin G (IgG) antibodies to the SFG rickettsiae. None of these sera were positive for IgG against typhus group rickettsiae. We detected Rickettsia africae-genotype DNA in 92.6% of adult Amblyomma variegatum ticks collected from domestic ruminants, but found no evidence of the pathogen in blood specimens from cattle, goats, or sheep. Sequencing of a subset of 21 rickettsia-positive ticks revealed R. africae variants in 95.2% (20/21) of ticks tested. Our findings show a high prevalence of R. africae variants in A. variegatum ticks in western Kenya, which may represent a low disease risk for humans. This may provide a possible explanation for the lack of African tick-bite fever cases among febrile patients in Kenya.

Rickettsioses and Q fever in travelers (2004-2013)

Rickettsioses (also called typhus) are associated with arthropods, including ticks, mites, fleas, and lice, although Q fever is more frequently acquired through the inhalation of contaminated aerosols or the consumption of milk. These zoonoses first emerged in the field of travel medicine 20 years ago. Here, we review rickettsioses and Q fever in travelers, highlighting cases reported in the past decade. African tick bite fever and Mediterranean spotted fever are the two most frequent spotted fevers. While the presentation of these fevers is typically benign, cardiac and neurological complications due to African tick bite fever have been reported, and Mediterranean spotted fever has been complicated by multi-organ failure and death in a few cases. Murine typhus and Q fever remain difficult to recognize and diagnose because these illnesses often present with only fever. New molecular tools, particularly when deployed with samples obtained from eschar swabs, might be easily implemented in laboratories with PCR facilities. Doxycycline must be introduced upon clinical suspicion of rickettsioses or Q fever and should be considered in cases of fever of unknown origin in travelers who are returning from at-risk geographic areas.

Update on tick-borne rickettsioses around the world: a geographic approach

Tick-borne rickettsioses are caused by obligate intracellular bacteria belonging to the spotted fever group of the genus Rickettsia. These zoonoses are among the oldest known vector-borne diseases. However, in the past 25 years, the scope and importance of the recognized tick-associated rickettsial pathogens have increased dramatically, making this complex of diseases an ideal paradigm for the understanding of emerging and reemerging infections. Several species of tick-borne rickettsiae that were considered nonpathogenic for decades are now associated with human infections, and novel Rickettsia species of undetermined pathogenicity continue to be detected in or isolated from ticks around the world. This remarkable expansion of information has been driven largely by the use of molecular techniques that have facilitated the identification of novel and previously recognized rickettsiae in ticks. New approaches, such as swabbing of eschars to obtain material to be tested by PCR, have emerged in recent years and have played a role in describing emerging tick-borne rickettsioses. Here, we present the current knowledge on tick-borne rickettsiae and rickettsioses using a geographic approach toward the epidemiology of these diseases.

Bell's palsy and sudden deafness associated with Rickettsia spp. infection in Sweden. A retrospective and prospective serological survey including PCR findings

BACKGROUND AND PURPOSE

Sixty patients with facial palsy and 67 with sudden deafness were retrospectively or prospectively examined for serological evidence of rickettsial infection; in six cases where cerebrospinal fluid was available, patients were also examined for presence of rickettsial DNA.

METHODS

Rickettsial antibodies were detected in single or paired serum samples using immunofluorescence with Rickettsia helvetica as the antigen and in four cases also using western blot. Using PCR and subsequent direct cycle sequencing, the nucleotide sequences of the amplicons (17 kDa protein gene) in cerebrospinal fluid were analysed.

RESULTS

Five out of 60 (8.3%) patients with facial palsy and eight of 67 (11.9%) with hearing loss showed confirmative serological evidence of infection with Rickettsia spp. An additional three and four patients in the facial palsy and hearing loss groups, respectively, showed evidence of having a recent or current infection or serological findings suggestive of infection. In four cases, the specificity of the reaction was confirmed by western blot. An additional 70 patients were seroreactive with IgG or IgM antibodies higher than or equal to the cut-off of 1:64, whereas 37 patients were seronegative. Only two of 127 patients had detectable antibodies to Borrelia spp. In three of six patients, rickettsial DNA was detected in the cerebrospinal fluid, where the obtained sequences (17 kDa) shared 100% similarity with the corresponding gene sequence of Rickettsia felis.

CONCLUSIONS

These results highlight the importance of considering Rickettsia spp. as a cause of neuritis, and perhaps as a primary cause of neuritis unrelated to neuroborreliosis.

Tick-borne relapsing fever with cutaneous eschar and radiculopathy, Ethiopia

We report the first confirmed case of tick-borne borreliosis by molecular tools in a French traveler returning from Ethiopia with unusual presentation: the presence of cutaneous eschar after a hard tick-bite suggesting firstly to clinicians a diagnosis of tick-borne rickettsiosis.

Rickettsia felis, an emerging flea-transmitted human pathogen

Rickettsia felis was first recognised two decades ago and has now been described as endemic to all continents except Antarctica. The rickettsiosis caused by R. felis is known as flea-borne spotted fever or cat-flea typhus. The large number of arthropod species found to harbour R. felis and that may act as potential vectors support the view that it is a pan-global microbe. The main arthropod reservoir and vector is the cat flea, Ctenocephalides felis, yet more than 20 other species of fleas, ticks, and mites species have been reported to harbour R. felis. Few bacterial pathogens of humans have been found associated with such a diverse range of invertebrates. With the projected increase in global temperature over the next century, there is concern that changes to the ecology and distribution of R. felis vectors may adversely impact public health.

Scrub typhus and rickettsial diseases in international travelers: a review

Physicians caring for febrile returned travelers face the difficult task of recognizing the typical and atypical features of more than 16 known rickettsial diseases and separating these diseases from potentially serious nonrickettsial diseases. Currently available diagnostic tools are inadequate for timely diagnosis. This review summarizes the English-language literature concerning imported rickettsial diseases in international travelers and describes important clinical principles in diagnosis and treatment of these illnesses. -Travelers with imported rickettsial disease often become sick before or within a few days of return from an endemic region. Illness that begins more than 18 days after return is unlikely to be rickettsial in origin. The absence of a skin rash or exposure to a vector should not dissuade clinicians from considering the possibility of a rickettsial disease in a returned traveler. Finally, if empiric therapy does not result in defervescence within 48 hours, an alternative nonrickettsial illness should be strongly considered.

Reversible hearing impairment: delayed complication of murine typhus or adverse reaction to azithromycin?

Delayed and reversible hearing loss occurred in a 55-year-old male patient with murine typhus infection. The patient had the initial symptoms of headache, fever and chills, followed by the occurrence of bilateral hearing loss on day 9 from fever onset. Murine typhus was diagnosed with a high IgM titre by indirect immunofluorescence assay. After treatment with azithromycin and prednisolone, the fever and other symptoms subsided gradually and bilateral hearing loss improved 3 weeks later. Though an adverse reaction to azithromycin could not be ruled out, delayed onset of hearing loss was more likely a complication of murine typhus, mainly because the hearing loss did not occur during the azithromycin usage period. Although hearing loss due to murine typhus is rare, clinicians should be alert to the existence of such a delayed complication.

African tick-bite fever: a new entity in the differential diagnosis of multiple eschars in travelers. Description of five cases imported from South Africa to Switzerland

African tick-bite fever (ATBF) is a newly described spotted fever rickettsiosis that frequently presents with multiple eschars in travelers returning from sub-Saharan Africa and, to a lesser extent, from the West Indies. It is caused by the bite of an infected Amblyomma tick, whose hunting habits explain the typical presence of multiple inoculation skin lesions and the occurrence of clustered cases. The etiological agent of ATBF is Rickettsia africae, an emerging tick-borne pathogenic bacterium. We describe herein a cluster of five cases of ATBF occurring in Swiss travelers returning from South Africa. The co-incidental infections in these five patients and the presence of multiple inoculation eschars, two features pathognomonic of this rickettsial disease, suggested the diagnosis of ATBF. Indeed, the presence of at least one inoculation eschar is observed in 53-100% of cases and multiple eschars in 21-54%. Two patients presented regional lymphadenitis and one a mild local lymphangitis. Though a cutaneous rash is described in 15-46% of cases, no rash was observed in our series. ATBF was confirmed by serology. Thus, ATBF has recently emerged as one of the most important causes of flu-like illness in travelers returning from Southern Africa. The presence of one or multiple eschars of inoculation is an important clinical clue to the diagnosis. It can be confirmed by serology or by PCR of a biopsy of the eschar. Culture can also be done in reference laboratories. Dermatologists and primary care physicians should know this clinical entity, since an inexpensive and efficient treatment is available.

Multicenter GeoSentinel analysis of rickettsial diseases in international travelers, 1996-2008

Spotted fever group rickettsiosis acquired in sub-Saharan Africa was the most common rickettsial disease observed.

New approaches to detection and identification of Rickettsia africae and Ehrlichia ruminantium in Amblyomma variegatum (Acari: Ixodidae) ticks from the Caribbean

Imported from Africa in the 1700s and despite frequent modern eradication efforts, Amblyomma variegatum (F.) spread through the Caribbean by cattle transport, small ruminants, and migrating birds. A. variegatum is a vector for Rickettsia africae, the causative agent of African tick bite fever, and Ehrlichia ruminantium, the causative agent of heartwater. We examined 95 A. variegatum and six Rhipicephalus (Boophilus) microplus (Canestrini) collected from cattle at an abattoir in Antigua. Engorged tick extracts adsorbed on Nobotu filter paper strips and new nested polymerase chain reaction (PCR) assays for E. ruminantium and Dermatophilus congolensis were used to evaluate these ticks for the presence of these pathogenic bacteria. Amblyomma ticks (62.4%) contained R. africae DNA by PCR/restriction fragment length polymorphism analysis and DNA sequencing of the OmpA and 17-kDa antigen genes. Twenty Amblyomma and two Rh. microplus contained E. ruminantium DNA. No E. chaffeensis, Anaplasma phagocytophilum, Coxiella burnetii, or D. congolensis DNA was detected in these ticks. The continued presence of Am. variegatum in the Caribbean poses a significant risk of infection in cattle with E. ruminantium and in humans by R. africae. Eradication efforts are essential to prevent the further spread of Am. variegatum.

African tick bite fever in elderly patients: 8 cases in French tourists returning from South Africa

BACKGROUND

African tick-bite fever, a tickborne disease caused by Rickettsia africae, is endemic in rural areas of sub-Saharan Africa and in the French West Indies. Most cases reported in the literature occurred in middle-aged, otherwise-healthy persons and corresponded to benign diseases. The course of African tick bite fever in elderly people is less well documented.

METHODS

The medical records of 8 elderly patients infected with R. africae during a trip to South Africa in 2005 are presented to summarize the epidemiologic, clinical, microbiological, treatment, and disease course characteristics.

RESULTS

Eight patients, aged 63-75 years, developed African tick bite fever symptoms after a trip to South Africa. R. africae was grown from cutaneous eschar biopsy specimens obtained from 4 patients, confirming African tick bite fever. We observed unusual findings in this elderly population. Rash was frequent (present in 87.5% of patients), vesicular (in 100% of patients with rash), and often associated with an enanthema (in 50% of patients with rash). Severe clinical manifestations occurred: lymphangitis and myocarditis in 1 patient and suspected brain involvement in 2 patients. We observed severe and long-lasting general symptoms, including fever (in 75% of patients), chills (87.5%), asthenia (50%), anorexia (50%), and weight loss (12.5%). With doxycycline therapy, the outcome was favorable in all cases, but complete recovery was slow.

CONCLUSION

Ecotourism to sub-Saharan Africa is expanding, and people of advanced age, often with underlying chronic diseases, account for an increasing proportion of travelers. African tick bite fever appears to be more symptomatic in this population. Recommendations advising personal prophylactic measures to prevent tick bites in travelers to regions of endemicity may be particularly important for elderly individuals.

African tick bite fever

Physicians may encounter unfamiliar diseases as a result of international travel. Fever with rash is an important sign that usually represents initial manifestation of infectious disorders. A 62-year-old Taiwanese woman presented with multiple eschars, a papulovesicular rash, and fever 5 days after returning from South Africa. A biopsy specimen of an eschar had wedge-shaped tissue necrosis, hemorrhage, necrotizing vasculitis of the small venules and arterioles, and a dense perivascular lymphocytic infiltrate in the dermis. Serologically, there was cross reaction with both Rickettsia conorii and R. rickettsii. DNA sequencing demonstrated R. africae, confirming the diagnosis of African tick bite fever. The patient responded well to minocycline. Recognition of the symptoms and signs, and diagnostic tools for different types of rickettsiosis are essential for correct diagnosis and treatment.