Human granulocytic anaplasmosis acquired in Connecticut, USA, diagnosed in Vienna, Austria, 2015

Human granulocytotropic anaplasmosis-A systematic review and analysis of the literature

Human granulocytotropic anaplasmosis (HGA) is a zoonotic tick-borne bacterial infection caused by Anaplasma phagocytophilum. While most cases are reported from North America, HGA has been recognized as an emerging disease in several regions of the world in recent decades. Most available data comes from case reports, case series and retrospective studies, while prospective studies and clinical trials are largely lacking. To obtain a clearer picture of the currently known epidemiologic distribution, clinical and paraclinical presentation, diagnostic aspects, complications, therapeutic aspects, and outcomes of HGA, we systematically reviewed the literature and analyzed and summarized the data. Cases of HGA are reported from all continents except from Antarctica. HGA primarily presents as an unspecific febrile illness (88.5% of the cases) often accompanied by thrombocytopenia (71.8% of the cases), abnormal liver injury tests (66.7% of the cases), and leukopenia (49.8% of the cases). Although we found complications reported in a total of 40.5% of the reviewed cases and severe and even life-threatening complications are not infrequent (e.g. acute renal failure 9.8%, multi organ failure 7.5%, ARDS 6.3%, a.o.), sequelae are rare (2.1% of the cases) and lethality is low (3.0% of the cases). Treatment with doxycycline shows a rapid response, with the fever subsiding in the majority of patients within one day of starting treatment. Unlike in human monocytotropic ehrlichiosis (HME), reports of opportunistic infections complicating HGA are rare. HGA during pregnancy does not appear to be associated with unfavorable outcomes. In addition, our analysis provides some evidence that HGA may differ in clinical aspects and laboratory characteristics in different regions of the world. Overall, the data analyzed indicates a non-negligible bias in reporting/publication, so a certain degree of caution is required when generalizing the data.

Human Granulocytic Anaplasmosis-A Systematic Review of Published Cases

Anaplasma phagocytophilum is an emerging, Gram-negative, obligate intracellular pathogen that is transmitted by a tick vector. Human infection ranges from asymptomatic to severe disease that can present with pancytopenia, multiorgan failure, and death. The aim of this systematic review is to analyze case reports and case series reported over the last two decades in peer-reviewed journals indexed in the Medline/PubMed database according to the PRISMA guidelines. We found 110 unique patients from 88 case reports and series. The most common mode of transmission was tick bite (60.9%), followed by blood transfusion (8.2%). Infection was acquired by blood transfusion in nearly half (42%) of the immunocompromised patients. Most patients reported fever (90%), followed by constitutional (59%) and gastrointestinal symptoms (56%). Rash was present in 17% of patients, much higher than in previous studies. Thrombocytopenia was the most common laboratory abnormality (76%) followed by elevated aspartate aminotransferase (AST) (46%). The diagnosis was most commonly established using whole-blood polymerase chain reaction (PCR) in 76% of patients. Coinfection rate was 9.1% and Borrelia burgdorferi was most commonly isolated in seven patients (6.4%). Doxycycline was used to treat 70% of patients but was only used as an empiric treatment in one-third of patients (33.6%). The overall mortality rate was 5.7%, and one patient died from trauma unrelated to HGA. The mortality rates among immunocompetent and immunocompromised patients were 4.2% (n = 4/95) and 18.2% (n = 2/11), respectively. Four of the six patients who died (66.6%) received appropriate antibiotic therapy. Among these, doxycycline was delayed by more than 48 h in two patients.

Parasitic and Vector-Borne Infections in HIV-Positive Patients in Slovakia-Evidence of an Unexpectedly High Occurrence of Anaplasma phagocytophilum

In HIV (human immunodeficiency virus) infected people, the immunodeficiency caused by a reduced level of CD4 (cluster of differentiation 4) T-lymphocytes increases the risk of infectious diseases. Additionally, in individuals with immunologically compromising conditions, tick-borne or some parasitic pathogens may cause chronic, debilitating opportunistic infections and even death. The study aimed at determining the IgG seropositivity of HIV-infected patients to Toxoplasma gondii, Toxocara spp., Echinococcus multilocularis, and E. granulosus s.l. and performing the molecular identification of T. gondii and some tick-borne pathogens, namely, Borrelia spp., Babesia spp., Anaplasma phagocytophilum, Rickettsia spp., and Bartonella spp. Out of 89 HIV-positive patients, specific IgG antibodies to T. gondii were detected in 17 (19.1%) and to Borrelia spp. in 12 (13.5%) individuals. Seropositivity to Toxocara spp., E. multilocularis, and E. granulosus s.l. was not recorded. Molecular approaches showed positivity to T. gondii in two (2.2%) patients, and 11 (12.4%) individuals had positive PCR signal for the msp2 gene of A. phagocytophilum. Relatively high prevalence of A. phagocytophilum in HIV-positive patients suggests that these people are more susceptible to some vector-borne pathogens. The presence of opportunistic infections may pose a health risk for patients with weakened immune systems, and should not be neglected during the regular monitoring of the patient’s health status.

Evaluation of Disease Causality of Rare Ixodes ricinus-Borne Infections in Europe

In Europe, Ixodes ricinus ticks transmit pathogens such as Borrelia burgdorferi sensu lato and tick-borne encephalitis virus (TBEV). In addition, there is evidence for transmission to humans from I. ricinus of Anaplasma phagocytophilum, Babesia divergens, Babesia microti, Babesia venatorum, Borrelia miyamotoi, Neoehrlichia mikurensis, Rickettsia helvetica and Rickettsia monacensis. However, whether infection with these potential tick-borne pathogens results in human disease has not been fully demonstrated for all of these tick-borne microorganisms. To evaluate the available evidence for a causative relation between infection and disease, the current study analyses European case reports published from 2008 to 2018, supplemented with information derived from epidemiological and experimental studies. The evidence for human disease causality in Europe found in this review appeared to be strongest for A. phagocytophilum and B. divergens. Nonetheless, some knowledge gaps still exist. Importantly, comprehensive evidence for pathogenicity is lacking for the remaining tick-borne microorganisms. Such evidence could be gathered best through prospective studies, for example, studies enrolling patients with a fever after a tick bite, the development of specific new serological tools, isolation of these microorganisms from ticks and patients and propagation in vitro, and through experimental studies.

Molecular Detection of Anaplasma phagocytophilum in Blood-Sucking Flies (Diptera: Tabanidae) in Poland

Anaplasma phagocytophilum is a pathogen of veterinary and medical importance. It is the causative agent of tick-borne fever (TBF) in ruminants (also known as bovine or ovine granulocytic anaplasmosis), and of human granulocytic anaplasmosis (HGA) in humans. In Europe, A. phagocytophilum is transmitted by Ixodes ricinus (Linnaeus 1758) ticks. The aim of this study was to confirm the presence of A. phagocytophilum DNA in blood-sucking flies belonging to the Tabanidae family using molecular methods. It represents the first detection of this pathogen in Haematopota pluvialis (Linnaeus 1758), Tabanus bromius (Linnaeus 1758), and Tabanus distinguendus (Verrall 1909) in Europe.

Update on Tick-Borne Bacterial Diseases in Travelers

PURPOSE OF REVIEW

Ticks are the second most important vectors of infectious diseases after mosquitoes worldwide. The growth of international tourism including in rural and remote places increasingly exposes travelers to tick bite. Our aim was to review the main tick-borne infectious diseases reported in travelers in the past 5 years.

RECENT FINDINGS

In recent years, tick-borne bacterial diseases have emerged in travelers including spotted fever group (SFG) rickettsioses, borrelioses, and diseases caused by bacteria of the Anaplasmataceae family. African tick-bite fever, due to Rickettsia africae, is the most frequent agent reported in travelers returned from Sub-Saharan areas. Other SFG agents are increasingly reported in travelers, and clinicians should be aware of them. Lyme disease can be misdiagnosed in Southern countries. Organisms causing tick-borne relapsing fever are neglected pathogens worldwide, and reports in travelers have allowed the description of new species. Infections due to Anaplasmataceae bacteria are more rarely described in travelers, but a new species of Neoehrlichia has recently been detected in a traveler. The treatment of these infections relies on doxycycline, and travelers should be informed before the trip about prevention measures against tick bites.

Occurrence and diversity of arthropod-transmitted pathogens in red foxes (Vulpes vulpes) in western Austria, and possible vertical (transplacental) transmission of Hepatozoon canis

Red fox (Vulpes vulpes) is the most abundant wild canid species in Austria, and it is a well-known carrier of many pathogens of medical and veterinary concern. The main aim of the present study was to investigate the occurrence and diversity of protozoan, bacterial and filarial parasites transmitted by blood-feeding arthropods in a red fox population in western Austria. Blood (n = 351) and spleen (n = 506) samples from foxes were examined by PCR and sequencing and the following pathogens were identified: Babesia canis, Babesia cf. microti (syn. Theileria annae), Hepatozoon canis, Anaplasma phagocytophilum, Candidatus Neoehrlichia sp. and Bartonella rochalimae. Blood was shown to be more suitable for detection of Babesia cf. microti, whilst the spleen tissue was better for detection of H. canis than blood. Moreover, extremely low genetic variability of H. canis and its relatively low prevalence rate observed in this study may suggest that the parasite has only recently been introduced in the sampled area. Furthermore, the data presented here demonstrates, for the first time, the possible vertical transmission of H. canis from an infected vixen to the offspring, and this could explain the very high prevalence in areas considered free of its main tick vector(s).

Direct detection of Anaplasma phagocytophilum by polymerase chain reaction followed by electrospray ionization mass spectrometry from human blood

Bacterial pathogens not detectable via commercial blood culture assays represent an important challenge for infectious disease physicians, in particular if clinical symptoms of the illness are non-specific. In this report, Anaplasma phagocytophilum was detected directly in a peripheral blood sample from a febrile patient reporting a tick bite. This was done using a commercial system based on PCR followed by electrospray ionization mass spectrometry (ESI-MS). The diagnosis of a human granulocytic anaplasmosis infection was established using this diagnostic methodology for the first time. Human granulocytic anaplasmosis is a neglected zoonotic disease in Europe. Its seroprevalence is similar in North America and Europe, but in contrast to the USA, it is rarely diagnosed in the old world. PCR followed by ESI-MS is a novel, complex, but highly promising diagnostic methodology for the rapid assessment of rare or exotic pathogens, including intracellular bacteria.