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

Rickettsia africae infections in sub-Saharan Africa: A systematic literature review of epidemiological studies and summary of case reports

Rickettsia africae is a tick-borne bacteria known to cause African tick bite fever (ATBF). While the disease was first described more than 100 years ago, knowledge of transmission risk factors and disease burden remain poorly described. To better understand the burden of R. africae, this article reviewed and summarized the published literature related to ATBF epidemiology and clinical management. Using a systematic approach, consistent with the PRISMA guidelines, we identified more than 100 eligible articles, including 65 epidemiological studies and 41 case reports. Most reports described R. africae in ticks and livestock, while human studies were less common. Human disease case reports were exclusively among returning travellers from non-endemic areas, which limits our disease knowledge among at-risk populations: people living in endemic regions. Substantial efforts to elucidate the ATBF risk factors and clinical manifestations among local populations are needed to develop effective preventative strategies and facilitate appropriate and timely diagnosis.

Molecular detection of Rickettsia africae from Amblyomma hebraeum ticks in Mafikeng city of North West Province, South Africa

Rickettsia africae causes zoonotic African tick bite fever, which is a disease of "One Health" importance. There have been reported cases of tourists from Europe and Asia who have been bitten by ticks whilst visiting South Africa's nature reserves, and on their return to their countries, the display African Tick Bite Fever sickness. Hence, the aim of this study was to determine the occurrence of Rickettsia africae in Amblyomma hebraeum ticks infesting livestock in the North West Province. A total of 358 A. hebraeum ticks were collected from 60 ruminants (cattle, sheep and goats) in Mafikeng City of North West Province, South Africa. Ticks were identified morphologically and further confirmed by sequencing of their ITS2 gene. DNA was extracted from 60 pools of ticks which consisted of 5-6 adult ticks that were from the same ruminant host. Infections with Rickettsia spp. were found in 48%, 40%, and 32% of cattle, sheep, and goats, respectively, in amplification by PCR using the ompA gene. The ompA gene sequences showed that the Rickettsia spp. were identified as R. africae. Although the animals from whom the ticks were collected did not exhibit any clinical symptoms, it is well recognised that R. africae is a disease with significant zoonotic potential. Thus, it is important to use the "One Health" approach to formulate prevention and control measures for this pathogen for animal and human health as well as the tourism sector due to the ecotourism importance of the resultant disease.

Knowledge, Attitudes, and Practices of Pastoralists Towards Tick Bites, and Tick Control in Plateau State, Nigeria

PURPOSE

Pastoralists regularly come in contact with ticks as they herd their animals and are exposed to pathogens that cause zoonotic diseases. No study has been conducted in Nigeria to evaluate the knowledge, attitudes, and practices (KAP) of these Pastoralists towards ticks, tick bite, and tick control, and thus this research.

METHODS

A KAP survey of pastoralists (n = 119) was conducted in Plateau State, Nigeria. Data generated were analysed using Statistical Package for Social Sciences (SPSS).

RESULTS

The majority of the pastoralists (99.2%) had knowledge of ticks, with 79% of them being aware that ticks attach and bite humans, whereas only 30.3% believed that ticks transmit diseases to humans. Eighty-four per cent of the pastoralists do not wear protective clothing while herding their animals and 81.5% indicated to having been bitten by ticks, whereas hospital visit after tick bite was low (7.6%). Statistically significant variables were observed when knowledge of the respondents were compared in relation to the ability of ticks to cause diseases (Χ² = 9.980, P = 0.007); hospital visit after a bite (Χ² = 11.453, P = 0.003); and the use of protective clothing for herding (Χ² = 22.596, P = 0). The main tick control measure was hand picking (58.8%).

CONCLUSIONS

The pastoralists were unaware of the ability of ticks to transmit zoonotic pathogens. Preventive practices were insufficient to reduce tick bites, and thus were constantly exposed to tick-borne diseases. This study hopes to provide important insights for the development of educational awareness programmes for the pastoralists and serve as a guide for the health workers in designing future preventive programmes against tick-borne zoonoses in Nigeria.

Rickettsia-Host-Tick Interactions: Knowledge Advances and Gaps

Ticks are hematophagous ectoparasites capable of transmitting multiple human pathogens. Environmental changes have supported the expansion of ticks into new geographical areas that have become the epicenters of tick-borne diseases (TBDs). The spotted fever group (SFG) of Rickettsia frequently infects ticks and causes tick-transmitted rickettsioses in areas of endemicity where ixodid ticks support host transmission during blood feeding. Ticks also serve as a reservoir for SFG Rickettsia. Among the members of SFG Rickettsia, R. rickettsii causes Rocky Mountain spotted fever (RMSF), the most lethal TBD in the United States. Cases of RMSF have been reported for over a century in association with several species of ticks in the United States. However, the isolation of R. rickettsii from ticks has decreased, and recent serological and epidemiological studies suggest that novel species of SFG Rickettsia are responsible for the increased number of cases of RMSF-like rickettsioses in the United States. Recent analyses of rickettsial genomes and advances in genetic and molecular studies of Rickettsia provided insights into the biology of Rickettsia with the identification of conserved and unique putative virulence genes involved in the rickettsial life cycle. Thus, understanding Rickettsia-host-tick interactions mediating successful disease transmission and pathogenesis for SFG rickettsiae remains an active area of research. This review summarizes recent advances in understanding how SFG Rickettsia species coopt and manipulate ticks and mammalian hosts to cause rickettsioses, with a particular emphasis on newly described or emerging SFG Rickettsia species.

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.

Imported African Tick Bite Fever in Japan: A Literature Review and Report of Three Cases

African tick bite fever (ATBF) is an acute febrile illness caused by Rickettsia africae. ATBF is an important differential diagnosis of acute febrile illness among returned travelers. However, little information is available on ATBF cases imported to Japan, as only seven have been reported to date. To characterize the epidemiological and clinical profiles of patients diagnosed with ATBF in Japan, we reported three new ATBF cases at our hospital between May 2015 and April 2018 and conducted a literature review.

Molecular Evidence for Flea-Borne Rickettsiosis in Febrile Patients from Madagascar

Rickettsiae may cause febrile infections in humans in tropical and subtropical regions. From Madagascar, no molecular data on the role of rickettsioses in febrile patients are available. Blood samples from patients presenting with fever in the area of the capital Antananarivo were screened for the presence of rickettsial DNA. EDTA (ethylenediaminetetraacetic acid) blood from 1020 patients presenting with pyrexia > 38.5 °C was analyzed by gltA-specific qPCR. Positive samples were confirmed by ompB-specific qPCR. From confirmed samples, the gltA amplicons were sequenced and subjected to phylogenetic analysis. From five gltA-reactive samples, two were confirmed by ompB-specific qPCR. The gltA sequence in the sample taken from a 38-year-old female showed 100% homology with R. typhi. The other sample taken from a 1.5-year-old infant was 100% homologous to R. felis. Tick-borne rickettsiae were not identified. The overall rate of febrile patients with molecular evidence for a rickettsial infection from the Madagascan study site was 0.2% (2/1020 patients). Flea-borne rickettsiosis is a rare but neglected cause of infection in Madagascar. Accurate diagnosis may prompt adequate antimicrobial treatment.

Molecular Detection of Coxiella burnetii, Rickettsia africae and Anaplasma Species in Ticks from Domestic Animals in Lesotho

Tick-borne diseases (TBDs) hamper the growth of the livestock sector and impose major constraints for the health and management of domestic animals in the tropic and subtropical regions globally. Currently, there is no scientific report on the presence of zoonotic pathogens transmitted by tick species in Lesotho. This study aimed to identify zoonotic tick-borne pathogens of economic importance from ticks infesting domestic animals in Lesotho using molecular techniques. A total of 322 tick DNA pools were subjected to PCR screening for the presence of zoonotic pathogens and sequenced. The overall prevalence of Anaplasma spp. was 35% (113/322), with a 100% infection rate in Rhipicephalus microplus, followed by R. evertsi evertsi (92%), Hyalomma rufipes and Otobius megnini sharing 50% and the lowest infection rate was observed in R. decoloratus with 40%. The prevalence of Coxiella burnetii, a gram-negative pleomorphic etiological agent of Query fever (Q fever), was 1% (2/322) for all screened samples, with 20% of R. decoloratus and 1% of R. e. evertsi infected. Rickettsia africae was detected from Hyalomma rufipes with a 70% prevalence. This study provides a baseline knowledge of tick-borne pathogens of medical and veterinary importance in Lesotho and raises awareness of the prevalence of such diseases within the tourism sector as they are mostly affected.

Epidemiologic and clinical profiles of bacterial myocarditis. Report of two cases and data from a pooled analysis

We aimed to characterize the epidemiology, diagnostic peculiarities and outcome determinants of bacterial myocarditis.

Two cases from our institution and literature reports were collected ending up with a total of 66 cases. In 37 (56%) patients, the diagnosis was confirmed by magnetic resonance and histopathological criteria. The other patients were classified as having possible myocarditis.

Only occurrence of rhythm disturbances was associated with the specific diagnosis of myocarditis (p = 0.04). Thirty-two (48%) patients presented with severe sepsis that was associated with a worse prognosis. At multivariate analysis, left ventricular ejection fraction (LVEF) at admission and heart rhythm disturbances were associated with incomplete recovery (odds ratio (OR) 1.1, 95% (CI) 1.03–1.2, p = 0.004 and OR 6.6, 95% CI 1.35–32.5, p = 0.02, respectively).

In summary, bacterial myocarditis is uncommon. Most commonly, it is secondary to septic dissemination of bacteria or to transient secondary myocardial toxicity.

Acute Myopericarditis Associated with Tickborne Rickettsia sibirica mongolitimonae

We report an unusual case of myopericarditis caused by Rickettsia sibirica mongolitimonae. Because of increasing reports of Rickettsia spp. as etiologic agents of acute myopericarditis and the ease and success with which it was treated in the patient reported here, rickettsial infection should be included in the differential diagnosis for myopericarditis.

Diagnosis of Spotted Fever Group Rickettsioses in U.S. Travelers Returning from Africa, 2007-2016

Spotted fever group rickettsioses (SFGRs), such as African tick bite fever (ATBF), are among the most commonly diagnosed diseases for ill travelers returning from southern Africa. We summarized demographic, clinical, and diagnostic features of imported SFGR cases in U.S. travelers returning from Africa who had laboratory specimens submitted to the Centers for Disease Control and Prevention. Diagnosis of SFGR was performed by indirect immunofluorescence antibody assay, immunohistochemical staining, polymerase chain reaction (PCR), or culture. Cases were defined as probable SFGR, confirmed SFGR, or confirmed ATBF. Clinical and epidemiological categorical variables were described as counts and proportions; continuous variables were described using geometric mean titers, median, and range. One hundred and twenty-seven patients satisfied laboratory criteria for confirmed or probable SFGR. Fever was the most common symptom (N = 88; 69%), followed by ≥ 1 eschars (N = 70; 55%). Paired serums were submitted for 36 patients (28%); 12 patients (33%) had nonreactive initial serum sample but converted to a titer ≥ 64 with the convalescent sample. Twenty-seven patients (21%) had infection with Rickettsia africae based on PCR analysis of eschar swab (N = 8) or biopsy (N = 23). Fifteen patients had eschar biopsy or swab samples and serum sample(s) submitted together; 9 (60%) had PCR-positive eschar results and nonreactive acute serology. Health-care providers should consider SFGR when evaluating patients for a febrile illness with eschar and compatible foreign travel history. Polymerase chain reaction testing of eschar biopsies or swabs provides a confirmed diagnosis in early stages of disease; eschar swabs or biopsies are an underutilized diagnostic technique.

Rickettsia sibirica mongolitimonae infection in a woman travelling from Cameroon: a case report and review of the literature

Rickettsia sibirica mongolitimonae is now a well-known cause of human rickettsial infection, with 52 reported cases, including 47 in southern Europe and one in South Africa. We report the first case of R. sibirica mongolitimonae in Central Africa, likely a sentinel case for a more common disease than originally suspected.

Rickettsia diversity in southern Africa: A small mammal perspective

Worldwide, including Africa, rickettsioses are recognized as emerging or re-emerging infections. To date, little is known about the diversity of Rickettsia species that are naturally associated with small mammals in southern Africa. The aim of the study was to screen a diversity of small mammals for the presence of rickettsial DNA. Animals were trapped at 38 localities in South Africa and Namibia. In total, 1616 ear-tissue samples from 23 species representing 17 genera were tested using real-time (rt)PCR and multi-locus sequence typing (MLST). Of the 1616 samples 251 (15.5%) were positive in an initial rtPCR. In 16 of the 23 investigated animal species rickettsial DNA was detected with an average prevalence of 15.7%. We herein describe for the first time four Rickettsia (R.) species known to be pathogenic for humans in rodents from South Africa, R. conorii, R. massiliae, R. felis and R. helvetica. In addition, by MLST and subsequent phylogenetic analyses so far undescribed Rickettsia species, Candidatus Rickettsia africaustralis, Candidatus Rickettsia rhabdomydis, and Candidatus Rickettsia muridii were confirmed. Further four new genotypes, genotype Rickettsia hofmannii, genotype Rickettsia stutterheimensis, genotype Rickettsia hogsbackensis and genotype Rickettsia kaalplaasensis, respectively, are described. The data indicate a surprisingly high diversity of Rickettsia in small mammals in South Africa and might indicate their possible role as reservoirs for Rickettsia. Ecological questions concerning their natural hosts such as small mammals, but also the role of livestock or pet animals, require further investigation. Particularly, data on the relevance of these rickettsiae for diseases in humans are of further interest.

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.

Molecular detection of pathogens in ticks infesting cattle in Nampula province, Mozambique

Ticks are ectoparasites that can act as vectors of a large number of pathogens in wild and domestic animals, pets, and occasionally humans. The global threat of emerging or re-emerging tick-borne diseases supports the need for research focused in the zoonotic transmission, especially in countries like Mozambique where rural populations are in close contact with domestic animals. The present study aims to: (1) identify tick species infesting cattle from Monapo and Nacala Porto, districts of Nampula province, Mozambique; and (2) investigate the presence of pathogens in the collected ticks. A total of 646 ticks were collected from cattle and morphologically identified as Amblyomma variegatum, Rhipicephalus microplus, and R. evertsi evertsi. For convenience, 72 A. variegatum and 15 R. microplus from Monapo, and 30 A. variegatum from Nacala Porto were screened for the presence of the selected pathogens: Rickettsia spp. (A. variegatum), and Babesia/Theileria spp. and Anaplasma/Ehrlichia spp. (R. microplus). Rickettsia africae was detected in four of the 72 A. variegatum collected in Monapo (5.6%). Additionally, one R. microplus tick (6.7%) was positive for Theileria velifera, one positive for Colpodella spp., one positive for Candidatus Midichloria mitochondrii, and another one positive for Anaplasma ovis. Using the present approach, no microorganisms were detected in tick samples from Nacala Porto. These findings expand our knowledge about the repertoire of tick-borne microorganisms in ticks in Nampula province, Mozambique.

African tick bite fever in returning Swedish travellers. Report of two cases and aspects of diagnostics

Introduction: African tick-bite fever, caused by Rickettsia africae, is endemic in rural areas of sub-Saharan Africa and a possible cause of fever in returning Swedish travellers. Two patients are presented, and the advantages and disadvantages of different diagnostic methods are discussed. Patients and methods: Two middle-aged men fell ill with fever after returning home from South Africa. Both had single eschars and one also presented with a lymph node swelling. Samples were taken for serology, general bacterial culture from the wound (Patient 1) using a swab and additionally for Patient 2 PCR of a skin biopsy from the eschar. Results and discussion: Both patients seroconverted one month after onset. Real-time PCR of the biopsy was positive, where sequencing of the gltA gene was 99-100% consistent with R. africae. A drop of fluid from the biopsy contained a sufficient number of bacteria to also allow for isolation of rickettsiae in Vero cell culture. Direct molecular detection by PCR from a swab used for bacteria culture from the eschar from Patient 1 also yielded a positive result. In conclusion, the findings highlight the usefulness of swabs for early non-invasive diagnosis of African tick-bite fever in febrile travellers.

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.

Occurrence of <i>Coxiella burnetii</i>, <i>Ehrlichia canis</i>, <i>Rickettsia</i> species and <i>Anaplasma phagocytophilum</i>-like bacterium in ticks collected from dogs and cats in South Africa

Ticks are major vectors of arthropod-borne infections and transmit a wide variety of zoonotic pathogens. This study was conducted mainly to determine the occurrence of canine tick-borne bacterial and rickettsial pathogens especially those with zoonotic potential. We examined 276 Rhipicephalus sanguineus, 38 Haemaphysalis elliptica and 4 Amblyomma hebraeum ticks from 90 dogs and 4 cats from the Free State, KwaZulu-Natal, North West and Mpumalanga provinces. DNA of Coxiella burnetii (41%), Ehrlichia or Anaplasma (18%), Rickettsia spp. (37%), Anaplasma phagocytophilum-like bacterium (18%) and Ehrlichia canis (19%) was detected by polymerase chain reaction (PCR) from a total of 147 pooled DNA samples. All samples were negative for the presence of Borrelia burgdorferi DNA. Ehrlichia canis was detected in samples from all the provinces except the North West; A. phagocytophilum was absent in KwaZulu-Natal samples, whereas Rickettsia species and C. burnetii were detected in all sampled provinces. The PCR-positive samples were confirmed by direct sequencing of the product. Data from this study calls for a joint effort by both veterinary and medical sectors to conduct epidemiological studies of the zoonotic pathogens in both animals and humans.

Molecular surveillance of spotted fever group rickettsioses in wildlife and detection of <i>Rickettsia sibirica</i> in a Topi (<i>Damaliscus lunatus</i> ssp. <i>jimela</i>) in Kenya

Spotted fever group rickettsioses are a group of tick-borne zoonotic diseases caused by intracellular bacteria of the genus Rickettsia. The diseases are widely reported amongst international travellers returning from most sub-Saharan Africa with fever, yet their importance in local populations largely remains unknown. Although this has started to change and recently there have been increasing reports of the diseases in livestock, ticks and humans in Kenya, they have not been investigated in wildlife. We examined the presence, prevalence and species of Rickettsia present in wildlife in two regions of Kenya with a unique human–wildlife–livestock interface. For this purpose, 79 wild animals in Laikipia County and 73 in Maasai Mara National Reserve were sampled. DNA extracted from blood was tested using the polymerase chain reaction (PCR) to amplify the intergenic spacer rpmE-tRNA^fMet and the citrate synthase-encoding gene gltA. Rickettsial DNA was detected in 2 of the 79 (2.5%) animals in Laikipia and 4 of the 73 (5.5%) in Maasai Mara. The PCR-positive amplicons of the gltA gene were sequenced to determine the detected Rickettsia species. This revealed Rickettsia sibirica in a Topi (Damaliscus lunatus ssp. jimela). This is the first report of spotted fever group rickettsioses in wildlife and the first to report R. sibirica in Kenya. The finding demonstrates the potential role of wild animals in the circulation of the diseases.

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.

Knowledge, Attitudes and Practices Towards Spotted Fever Group Rickettsioses and Q Fever in Laikipia and Maasai Mara, Kenya

Many factors contribute to misdiagnosis and underreporting of infectious zoonotic diseases in most sub-Saharan Africa including limited diagnostic capacity and poor knowledge. We assessed the knowledge, practices and attitudes towards spotted fever group rickettsioses (SFGR) and Q fever amongst local residents in Laikipia and Maasai Mara in Kenya. A semi-structured questionnaire was administered to a total of 101 respondents including 51 pastoralists, 17 human health providers, 28 wildlife sector personnel and 5 veterinarians. The pastoralists expressed no knowledge about SFGR and Q fever. About 26.7% of the wildlife sector personnel in Laikipia expressed some knowledge about SFGR and none in Maasai Mara. None of these respondents had knowledge about Q fever. About 45.5 and 33.3% of the health providers in Laikipia and Maasai Mara respectively expressed knowledge about SFGR and 9.1% in Laikipia expressed good knowledge on Q fever and none in Maasai Mara. The diseases are not considered amongst potential causes of febrile illnesses in most medical facilities except in one facility in Laikipia. Majority of pastoralists practiced at least one predisposing activity for transmission of the diseases including consumption of raw milk, attending to parturition and sharing living accommodations with livestock. Education efforts to update knowledge on medical personnel and One-Health collaborations should be undertaken for more effective mitigation of zoonotic disease threats. The local communities should be sensitized through a multidisciplinary approach to avoid practices that can predispose them to the diseases.

Ouderen op reis

Ouderen reizen steeds meer, maar met de leeftijd neemt de kans toe om op reis te overlijden. De oorzaak hiervan is meestal een verergering van vooraf bestaande gezondheidsaandoeningen, eventueel uitgelokt door reisgerelateerde stress en vermoeidheid, infecties en hitte. Ook de hogere leeftijd zelf is echter verantwoordelijk voor een deel van de oversterfte, doordat de afweer afneemt met als gevolg meer kans op ernstige infecties. Daarnaast zijn ouderen gevoeliger voor diepveneuze trombose, dehydratie, temperatuurverschillen en jetlag. Een goede voorbereiding en rekening houden met de specifieke risico’s van een hogere leeftijd, zorgen ervoor dat ook ouderen in het algemeen veilig kunnen reizen.

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.

Queensland tick typhus: three cases with unusual clinical features

Queensland tick typhus (QTT), caused by Rickettsia australis, is usually a relatively mild illness but can occasionally be severe. We describe three cases of probable QTT with unusual clinical features, namely splenic infarction, fulminant myopericarditis and severe leukocytoclastic vasculitis. QTT may present with uncommon clinical features in addition to the more common manifestations. A high index of suspicion enables specific antibiotic therapy that may hasten recovery.

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.

Treatment of Rickettsia spp. infections: a review

Human rickettsioses caused by intracellular bacteria of the genus Rickettsia are distributed worldwide and are transmitted by arthropod vectors such as ticks, fleas, mites and lice. They have a wide range of manifestations from benign to life-threatening diseases. Mortality rates of up to 30% have been reported for some rickettsioses. Here, the authors will review in vitro and human studies of the various compounds that have been used for the treatment of Rickettsia spp. infections. The authors will also provide recommendations for the treatment of spotted fever and typhus group rickettsioses.

Utilization of multiple real-time PCR assays for the diagnosis of Bordetella spp. in clinical specimens

Bordetella pertussis causes an upper respiratory infection in infants, adolescents, and adults. Diagnosis of pertussis, a vaccine-preventable disease, can be difficult, but recent implementation of real-time PCR assays in laboratories has hastened the ability of clinicians to make an accurate diagnosis. In this paper we describe the method of nasopharyngeal specimen collection, extraction of DNA, and real-time PCR assays that will allow the detection and identification of Bordetella spp. in clinical specimens.

Travel-associated illness in older adults (>60 y)

BACKGROUND

Older individuals represent a substantial proportion of international travelers. Because of physiological changes and the increased probability of underlying medical conditions, older travelers might be at higher risk for at least some travel-associated diseases.

METHODS

With the aim of describing the epidemiology of travel-associated diseases in older adults, medical data were prospectively collected on ill international travelers presenting to GeoSentinel sites from 1997 to 2009. Seven thousand thirty-four patients aged 60 years and over were identified as older travelers and were compared to 56,042 patients aged 18-45 years, who were used as the young adult reference population.

RESULTS

The proportionate morbidity of several etiological diagnoses was higher in older ill travelers compared to younger ill, including notably lower respiratory tract infections, high-altitude pulmonary edema, phlebitis and pulmonary embolism, arthropod bites, severe malaria, rickettsiosis, gastritis, peptic ulcers, esophagitis and gastroesophageal reflux disease, trauma and injuries, urinary tract infections, heart disease, and death. In contrast, acute diarrhea, upper respiratory tract infections, flu and flu-like illnesses, malaria, dengue, genital infections, sexually transmitted diseases, and schistosomiasis proportionate morbidities were lower among the older group.

CONCLUSION

Older ill travelers are more likely to suffer from certain life-threatening diseases and would benefit from reinforcement of specific preventive measures including use of anti-thrombosis compression stockings and sufficient hydration and exercises during long-distance flights, hand hygiene, use of disposable handkerchiefs, consideration of face-masks in crowded conditions, influenza and pneumococcal vaccines, progressive acclimatization to altitude, consideration of acetazolamide, and use of repellents and mosquito nets. Antibiotics for the presumptive treatment of respiratory and urinary tract infections may be considered, as well as antacid medications. At-risk patients should be referred to a specialist for medical evaluation before departing, and optimal control of co-morbidities such as cardiovascular and chronic obstructive pulmonary diseases should be achieved, particularly for high-altitude travel.

Molecular diagnostics of Rickettsia africae infection in travelers returning from South Africa to The Netherlands

BACKGROUND

African tick-bite fever (ATBF) is frequently diagnosed in The Netherlands in travelers returning from South Africa. It is caused by Rickettsia africae and diagnosis is based on travel history and clinical presentation and usually confirmed by detecting serum antibodies against rickettsiae of the spotted fever group. However, these typically occur late in the course of the disease, and a mild clinical course or early antibiotic treatment can diminish antibody production.

METHODS AND RESULTS

Four travelers presented with (sub)febrile temperatures and eschar(s), several days after returning from South Africa. R. africae DNA was amplified and sequenced from skin biopsies of the eschars of all patients. Initial immunofluorescence assays yielded no immunoglobulin M (IgM)/IgG antibodies directed against spotted fever group rickettsiae; however, serology in the convalescent phase-several weeks after the patients had fully recovered-was positive.

CONCLUSIONS

ATBF should be considered in travelers returning from South Africa to The Netherlands with febrile illness and (multiple) skin lesions. The diagnosis can be confirmed by (paired) serology; however, polymerase chain reaction and sequencing on skin biopsies could be a (faster and more accurate) confirmatory test. Advantages of molecular methods over serology are species identification and high sensitivity early in the course of the disease.

Host, pathogen and treatment-related prognostic factors in rickettsioses

Diseases caused by rickettsiae, which are vector-borne bacteria, vary widely from mild and self-limiting, to severe and life-threatening. Factors influencing this diversity of outcome are related to the host, to the infectious agent and to the treatment used to treat the infection. A literature search was conducted on PubMed using the phrases "factors-related severity, outcome, host, pathogen, Rickettsia conorii, R. rickettsii, R. africae, R. felis, R. prowazekii, R. typhi, genomics". Among host factors, old age and the male gender have been associated with poor outcome in rickettsioses. Co-morbidities, ethnical factors and the genetic background of the host also seem to influence the outcome of rickettsial diseases. Moreover, although the degree of the host response is beneficial, it could also partly explain the severity observed in some patients. Among pathogen-related factors, traditional concepts of factors of virulence had been challenged and genomic reductive evolution with loss of regulatory genes is the main hypothesis to explain virulence observed in some species, such as Rickettsia prowazekii, the agent of epidemic typhus. R. prowazekii is the more pathogenic rickettsiae and harbours the smaller genome size (1.1 Mb) compared to less or non-virulent species, and is not intracellularly motile, a factor considered as a virulence factor for other intracellular bacteria. The antibiotic regimen used to treat rickettsioses also has an influence on prognosis. Usual concepts of severity and virulence in rickettsioses are challenging and are frequently paradoxical. In this mini-review, we will describe factors currently thought to influence the outcome of the main rickettsioses responsible for illness in humans.

Rickettsia africae in Amblyomma variegatum and domestic ruminants on eight Caribbean islands

We used PCRs with omp A primers to determine if spotted fever group rickettsiae occurred in Amblyomma variegatum from 6 Caribbean islands. Positive amplicons were obtained from ticks from the U.S. Virgin Islands (9/18; 50%), Dominica (39/171; 30%), Montserrat (2/5; 40%), Nevis (17/34; 50%), St. Kitts (46/227; 20%), and St. Lucia (1/14; 7%). Sequences for a convenience sample of reaction products obtained from A. variegatum on St. Kitts (7), American Virgin Islands (4), Montserrat (2), and St. Lucia (1) were 100% homologous with that of Rickettsia africae , the agent of African tick-bite fever. To determine if transmission of R. africae occurred, we used Rickettsia rickettsii antigen in IFA tests and found positive titers (≥ 1/80) with sera from cattle, goats, and sheep from Dominica (24/95 [25%], 2/136 [2%], 0/58 [0%]), Nevis (12/45 [27%], 5/157 [3%], 0/90 [0%]), St. Kitts (2/43 [5%], 1/25 [4%), 1/35 [3%]), and St. Lucia (6/184 [3%] cattle), respectively. No seropositive animals were found in Grenada (0/4, 0/98/, 0/86), Montserrat (0/12, 0/26, 0/52), or Puerto Rico (0/80 cattle). Our study indicates that R. africae and African tick-bite fever are widespread in the Caribbean.

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.

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.