A case of transfusion-transmission Anaplasma phagocytophilum from leukoreduced red blood cells.

BACKGROUND: Anaplasma phagocytophilum is a tick-borne bacterium and the cause of human granulocytic anaplasmosis (HGA). Here, we report a case of transfusion-transmitted (TT)-HGA involving a leukoreduced (LR) red blood cell (RBC) unit. CASE REPORT: A 64-year-old woman with gastric adenocarcinoma and multiple myeloma who received weekly blood transfusions developed persistent fevers, hypotension, and shortness of breath 1 week after receiving an RBC transfusion. Persistent fevers, new thrombocytopenia, and transaminitis suggested a tick-borne infection. RESULTS: The absence of blood parasites on thick and thin blood smears suggested that malaria and Babesia infection were not present, and the recipient tested negative for antibodies to Borrelia burgdorferi. Blood testing by polymerase chain reaction (PCR) for Ehrlichia and Anaplasma species identified A. phagocytophilum. Treatment with doxycycline resolved the infection; however, the recipient expired due to complications of her known malignancies. The recipient lived in a nursing home and did not have pets or spend time outdoors. The donor was a female in her 70s from Maine who was diagnosed with HGA 3 weeks after donating blood and whose LR-RBCs from the donation were transfused to the recipient 9 days following collection. CONCLUSION: This is a confirmed case of TT-HGA. Although rare, TT-HGA has been reported with LR-RBCs and platelets. In endemic areas, testing for tick-borne associated infections should be considered when investigating post-transfusion complications.

Specific and Sensitive Diagnosis of Babesia microti Active Infection Using Monoclonal Antibodies to the Immunodominant Antigen BmGPI12.

The apicomplexan pathogen Babesia microti is responsible for most cases of human babesiosis worldwide. The disease, which presents as a malaria-like illness, is potentially fatal in immunocompromised or elderly patients, making the need for its accurate and early diagnosis an urgent public health concern. B. microti is transmitted primarily by Ixodes ticks but can also be transmitted via blood transfusion. The parasite completes its asexual reproduction in the host red blood cell, where each invading merozoite develops and multiplies to produce four daughter parasites. While various techniques, such as microscopy, PCR, and indirect fluorescence, have been used over the years for babesiosis diagnosis, detection of the secreted B. microti immunodominant antigen BmGPI12 using specific polyclonal antibodies was found to be the most effective method for the diagnosis of active infection and for evaluation of clearance following drug treatment. Here, we report the development of a panel of 16 monoclonal antibodies against BmGPI12. These antibodies detected secreted BmGPI12 in the plasma of infected humans. Antigen capture assays identified a combination of two monoclonal antibodies, 4C8 and 1E11, as a basis for a monoclonal antibody-based BmGPI12 capture assay (mGPAC) to detect active B. microti infection. Using a collection of 105 previously characterized human plasma samples, the mGPAC assay showed 97.1% correlation with RNA-based PCR (transcription-mediated amplification [TMA]) for positive and negative samples. The mGPAC assay also detected BmGPI12 in the plasma of six babesiosis patients at the time of diagnosis but not in three matched posttreatment samples. The mGPAC assay could thus be used alone or in combination with other assays for accurate detection of active B. microti infection.

[Clinicopathological profile of patients with hepatobiliary cancers at two main referral hospitals in Lima, Peru]. / Perfil clínico-patológico de pacientes con cáncer hepatobiliar en dos hospitales de referencia en Lima, Perú.

OBJECTIVE: The aim of the study was to describe the clinicopathological profile of patients diagnosed with liver, bile ducts or gallbladder cancer. MATERIALS AND METHODS: Between 2006 and 2017, 89 patients (57% female; mean age: 62 years-old) with these cancers were diagnosed at two national hospitals in Lima, Peru. RESULTS: Most patients (64%) had advanced stages of disease. Anemia was more frequent in patients with bile duct and liver cancer and in advanced stages. Hypertension (HTN) was frequent among liver cancer patients (32%). The analysis by age showed that HTN was more frequent in patients over 50 years. Likewise, people under 50 years had more frequent history of previous infections (50%), Hepatitis B (HBV) being the most common. CONCLUSIONS: This study describes the baseline clinicopathological characteristics of a malignancy poorly studied in Peru.

High-dose methylprednisolone in nonintubated patients with severe COVID-19 pneumonia.

BACKGROUND: Recent trials with dexamethasone and hydrocortisone have demonstrated benefit in patients with coronavirus disease 2019 (COVID-19). Data on methylprednisolone are limited. METHODS: Retrospective cohort of consecutive adults with severe COVID-19 pneumonia on high-flow oxygen (FiO2  ≥ 50%) admitted to an academic centre in New York, from 1 March to 15 April 2020. We used inverse probability of treatment weights to estimate the effect of methylprednisolone on clinical outcomes and intensive care resource utilization. RESULTS: Of 447 patients, 153 (34.2%) received methylprednisolone and 294 (65.8%) received no corticosteroids. At 28 days, 102 patients (22.8%) had died and 115 (25.7%) received mechanical ventilation. In weighted analyses, risk for death or mechanical ventilation was 37% lower with methylprednisolone (hazard ratio 0.63; 95% CI 0.47-0.86; P = .003), driven by less frequent mechanical ventilation (subhazard ratio 0.56; 95% CI 0.40-0.79; P = .001); mortality did not differ between groups. The methylprednisolone group had 2.8 more ventilator-free days (95% CI 0.5-5.1; P = .017) and 2.6 more intensive care-free days (95% CI 0.2-4.9; P = .033) during the first 28 days. Complication rates were not higher with methylprednisolone. CONCLUSIONS: In nonintubated patients with severe COVID-19 pneumonia, methylprednisolone was associated with reduced need for mechanical ventilation and less-intensive care resource utilization without excess complications.

Presence of Borrelia miyamotoi infection in a highly endemic area of Lyme disease.

A series of cases in the Northeast of the US during 2013-2015 described a new Borrelia species, Borrelia miyamotoi, which is transmitted by the same tick species that transmits Lyme disease and causes a relapsing fever-like illness. The geographic expansion of B. miyamotoi in the US also extends to other Lyme endemic areas such as the Midwestern US. Co-infections with other tick borne diseases (TBD) may contribute to the severity of the disease. On Long Island, NY, 3-5% of ticks are infected by B. miyamotoi, but little is known about the frequency of B. miyamotoi infections in humans in this particular region. The aim of this study was to perform a chart review in all patients diagnosed with B. miyamotoi infection in Stony Brook Medicine (SBM) system to describe the clinical and epidemiological features of B. miyamotoi infection in Suffolk County, NY. In a 5 year time period (2013-2017), a total of 28 cases were positive for either IgG EIA (n = 19) or PCR (n = 9). All 9 PCR-positive cases (median age: 67; range: 22-90 years) had clinical findings suggestive of acute or relapsing infection. All these patients were thought to have a TBD, prompting the healthcare provider to order the TBD panel which includes a B. miyamotoi PCR test. In conclusion, B. miyamotoi infection should be considered in the differential diagnosis for flu-like syndromes during the summer after a deer tick bite and to prevent labeling a case with Lyme disease.

Cutaneous Mycobacterial Infections.

Humans encounter mycobacterial species due to their ubiquity in different environmental niches. In many individuals, pathogenic mycobacterial species may breach our first-line barrier defenses of the innate immune system and modulate the activation of phagocytes to cause disease of the respiratory tract or the skin and soft tissues, sometimes resulting in disseminated infection. Cutaneous mycobacterial infections may cause a wide range of clinical manifestations, which are divided into four main disease categories: (i) cutaneous manifestations of Mycobacterium tuberculosis infection, (ii) Buruli ulcer caused by Mycobacterium ulcerans and other related slowly growing mycobacteria, (iii) leprosy caused by Mycobacterium leprae and Mycobacterium lepromatosis, and (iv) cutaneous infections caused by rapidly growing mycobacteria. Clinically, cutaneous mycobacterial infections present with widely different clinical presentations, including cellulitis, nonhealing ulcers, subacute or chronic nodular lesions, abscesses, superficial lymphadenitis, verrucous lesions, and other types of findings. Mycobacterial infections of the skin and subcutaneous tissue are associated with important stigma, deformity, and disability. Geography-based environmental exposures influence the epidemiology of cutaneous mycobacterial infections. Cutaneous tuberculosis exhibits different clinical phenotypes acquired through different routes, including via extrinsic inoculation of the tuberculous bacilli and dissemination to the skin from other sites, or represents hypersensitivity reactions to M. tuberculosis infection. In many settings, leprosy remains an important cause of neurological impairment, deformity, limb loss, and stigma. Mycobacterium lepromatosis, a mycobacterial species related to M. leprae, is linked to diffuse lepromatous leprosy of Lucio and Latapí. Mycobacterium ulcerans produces a mycolactone toxin that leads to subcutaneous tissue destruction and immunosuppression, resulting in deep ulcerations that often produce substantial disfigurement and disability. Mycobacterium marinum, a close relative of M. ulcerans, is an important cause of cutaneous sporotrichoid nodular lymphangitic lesions. Among patients with advanced immunosuppression, Mycobacterium kansasii, the Mycobacterium avium-intracellulare complex, and Mycobacterium haemophilum may cause cutaneous or disseminated disease. Rapidly growing mycobacteria, including the Mycobacterium abscessus group, Mycobacterium chelonei, and Mycobacterium fortuitum, are increasingly recognized pathogens in cutaneous infections associated particularly with plastic surgery and cosmetic procedures. Skin biopsies of cutaneous lesions to identify acid-fast staining bacilli and cultures represent the cornerstone of diagnosis. Additionally, histopathological evaluation of skin biopsy specimens may be useful in identifying leprosy, Buruli ulcer, and cutaneous tuberculosis. Molecular assays are useful in some cases. The treatment for cutaneous mycobacterial infections depends on the specific pathogen and therefore requires a careful consideration of antimicrobial choices based on official treatment guidelines.

Infection with New York Orthohantavirus and Associated Respiratory Failure and Multiple Cerebral Complications.

We report a case of infection with New York orthohantavirus in a woman who showed renal impairment and hemorrhage, complicated by hydrocephalus, in Long Island, New York, USA. Phylogenetic analysis showed that this virus was genetically similar to a New York orthohantavirus isolated in the same region during 1993.

Screening the Pathogen Box for Identification of New Chemical Agents with Anti-Fasciola hepatica Activity.

Fascioliasis is an infectious parasitic disease distributed globally and caused by the liver fluke Fasciola hepatica or F. gigantica This neglected tropical disease affects both animals and humans, and it represents a latent public health problem due to the significant economic losses related to its effects on animal husbandry. For decades, triclabendazole has been the unique anti-Fasciola drug that can effectively treat this disease. However, triclabendazole resistance in fascioliasis has more recently been reported around the world, and thus, the discovery of novel drugs is an urgent need. The aim of this study was to investigate the fasciocidal properties of 400 compounds contained in the Pathogen Box. The first stage of the screening was carried out by measuring the fasciocidal activity on metacercariae at a concentration of 33 µM each compound (the standard dose). Subsequently, the activities of the most active compounds (n = 33) at their 50% inhibitory concentration (IC50) values against metacercariae were assayed, and the results showed that 13 compounds had IC50s of ≤10 µM. The second stage queried the activities of these compounds at 33 µM against adult flukes, with seven of the compounds producing high mortality rates of >50%. Four hit compounds were selected on the basis of their predicted nontoxic properties, and the IC50 values obtained for adult worms were <10 µM; thus, these compounds represented the best fasciocidal compounds tested here. A cytotoxicity assay on four types of cell lines demonstrated that three compounds were nontoxic at their most active concentration. In conclusion, three hit compounds identified in this proof-of-concept study are potential candidates in the discovery of new fasciocidal drugs. Further studies are warranted.

Mycobacterium orygis Lymphadenitis in New York, USA.

We report a case of lymphadenitis caused by Mycobacterium orygis in an immunocompetent person in Stony Brook, New York, USA. Initial real-time PCR assay failed to provide a final subspecies identification within the M. tuberculosis complex, but whole-genome sequencing characterized the isolate as M. orygis.

A computational assessment of the predicted structures of Human Macrophage Migration Inhibitory Factor 1 orthologs in parasites and its affinity to human CD74 receptor.

The human macrophage migration inhibitory factor 1 (Hu-MIF-1) is a protein involved in the inflammatory and immunology response to parasite infection. In the present study, the existence of Hu-MIF-1 from parasites have been explored by mining WormBase. A total of 35 helminths were found to have Hu-MIF-1 homologs, including some parasites of importance for public health. Physicochemical, structural, and biological properties of Hu-MIF-1 were compared with its orthologs in parasites showing that most of these are secretory proteins, with positive net charge and presence of the Cys-Xaa-Xaa-Cys motif that is critical for its oxidoreductase activity. The inhibitor-binding site present in Hu-MIF-1 is well conserved among parasite MIFs suggesting that Hu-MIF inhibitors may target orthologs in pathogens. The binding of Hu-MIF-1 to its cognate receptor CD74 was predicted by computer-assisted docking, and it resulted to be very similar to the predicted complexes formed by parasite MIFs and human CD74. More than 1 plausible conformation of MIFs in the extracellular loops of CD74 may be possible as demonstrated by the different predicted conformations of MIF orthologs in complex with CD74. Parasite MIFs in complex with CD74 resulted with some charged residues oriented to CD74, which was not observed in the Hu-MIF-1/CD74 complex. Our findings predict the binding mode of Hu-MIF-1 and orthologs with CD74, which can assist in the design of novel MIF inhibitors. Whether the parasite MIFs function specifically subvert host immune responses to suit the parasite is an open question that needs to be further investigated. Future research should lead to a better understanding of parasite MIF action in the parasite biology.

Babesiosis in Long Island: review of 62 cases focusing on treatment with azithromycin and atovaquone.

BACKGROUND: Babesiosis is a potentially life-threatening, tick-borne infection endemic in New York. The purpose of this study was to review recent trends in babesiosis management and outcomes focusing on patients, who were treated with combination of azithromycin and atovaquone. METHODS: A retrospective chart review of patients seen at Stony Brook University Hospital between 2008 and 2014 with peripheral blood smears positive for Babesia was performed. Clinical and epidemiological information was recorded and analyzed. RESULTS: 62 patients had confirmed babesiosis (presence of parasitemia). Forty six patients (74%) were treated exclusively with combination of azithromycin and atovaquone; 40 (87%) of these patients were hospitalized, 11 (28%) were admitted to Intensive Care Unit (ICU), 1 (2%) died. Majority of patients presented febrile with median temperature 38.5 °C. Median peak parasitemia among all patients was 1.3%, and median parasitemia among patients admitted to ICU was 5.0%. Six patients (15%) required exchange transfusion. Majority of patients (98%) improved and were discharged from hospital or clinic. CONCLUSION: Symptomatic babesiosis is still rare even in endemic regions. Recommended treatment regimen is well tolerated and effective. Compared to historical controls we observed a lower overall mortality.

Carcinogenesis associated with parasites other than Schistosoma, Opisthorchis and Clonorchis: A systematic review.

Only three helminths (Schistosoma haematobium, Opisthorchis viverrini and Clonorchis sinensis) are directly associated with carcinogenesis in humans whereas the role of other parasites in cancer remains unclear. This study aimed to perform a systematic review to identify recent insights in the role of other parasite infections in carcinogenesis. We conducted systematic searches of MEDLINE and EMBASE on July 2015. Our primary outcome was the association between parasitic infections and carcinogenesis. Out of 1,266 studies, 19 were selected for detailed evaluation (eight for helminths and 11 for protozoa). The mechanisms of helminth-induced cancer included chronic inflammation, sustained proliferation, modulation of the host immune system, reprogramming of glucose metabolism and redox signaling, induction of genomic instability and destabilization of suppressor tumor proteins, stimulation of angiogenesis, resisting cell death, and activation of invasion and metastasis. In addition to the current knowledge, the following parasites were found in cancers or tumors: Echinococcus, Strongyloides, Fasciola, Heterakis, Platynosomum and Trichuris. Additional parasites were found in this systematic review that could potentially be associated with cancers or tumors but further evidence is needed to elaborate a cause-effect relationship.

Irritable bowel syndrome and intestinal parasites: a view from South America.

Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder of uncertain etiology. Several studies have proposed the possible role of intestinal parasites in the pathogenesis of IBS. We aimed to summarize the epidemiological studies that describe a possible link between intestinal parasites and IBS, with special interest in endemic areas for intestinal parasitism such as South America. A comprehensive review of the literature was conducted by using the keywords: irritable bowel syndrome, intestinal parasites, protozoan infection, soil-transmitted helminths and South America. Giardia lamblia may cause IBS symptoms that can persist several years after effective treatment. Dientamoeba fragilis can cause IBS-like symptoms, but low sensitive parasitological techniques may fail to detect it. Entamoeba histolytica can cause a chronic non-dysenteric colitis, but several studies have failed to find an association with IBS. The role of Blastocystis hominis in IBS remains controversial. In addition, epidemiological studies evaluating the effect of soil-transmitted helminths in IBS are scant. Symptoms elicited by intestinal parasites may resemble to those in IBS, especially in endemic areas such as South America, where both the prevalence of IBS and intestinal parasitism are high. Whether these organisms are the cause or contributing factors in IBS remains a subject of study. Routine parasitologicalexamination of stools in individuals who full-fit the criteria for IBS should be included upon initial assessment in endemic countries.

Zoonotic Leprosy in the Southeastern United States.

Nine-banded armadillos (Dasypus novemcinctus) are naturally infected with Mycobacterium leprae and have been implicated in zoonotic transmission of leprosy. Early studies found this disease mainly in Texas and Louisiana, but armadillos in the southeastern United States appeared to be free of infection. We screened 645 armadillos from 8 locations in the southeastern United States not known to harbor enzootic leprosy for M. leprae DNA and antibodies. We found M. leprae-infected armadillos at each location, and 106 (16.4%) animals had serologic/PCR evidence of infection. Using single-nucleotide polymorphism variable number tandem repeat genotyping/genome sequencing, we detected M. leprae genotype 3I-2-v1 among 35 armadillos. Seven armadillos harbored a newly identified genotype (3I-2-v15). In comparison, 52 human patients from the same region were infected with 31 M. leprae types. However, 42.3% (22/52) of patients were infected with 1 of the 2 M. leprae genotype strains associated with armadillos. The geographic range and complexity of zoonotic leprosy is expanding.

Indigenous Cases of Leprosy (Hansen's Disease) in Southern Mississippi.

Hansen's disease or leprosy is a chronic infection of the skin and peripheral nerves caused by Mycobacterium leprae. In the U.S., leprosy is mainly reported in immigrants, but indigenous leprosy cases have been also reported in this country, especially in semitropical southern states (i.e., Texas, Louisiana). The objective of this series of cases is to describe indigenous leprosy cases reported in southern Mississippi (MS) during the period 2012-2014. Information was collected from medical records at Hattiesburg Clinic and the MS Department of Health. Four cases were reported during the period of study (3 Caucasian males, 1 African-American woman). Non of visited endemic leprosy country. The age ranged from 60 to 83 years (median: 75.5 years). Of the four cases, three presented with a slowly progressive erythematous rash disseminated mainly on the thorax and abdomen, with a lesser degree on the extremities. The time between onset of rash until the diagnosis ranged from 5 to 16 months (median: 7 months). Only one case had direct contact with armadillos (blood exposure). Non of these patients had a history of immunosuppression. The most common symptoms were neuropathic pain (n=2), generalized pruritus (n=2) and loss of sensation in extremities (n=2). One case had severe peripheral neuropathy with muscle weakness, atrophy in left arm, and wasting on left hand. Skin biopsies showed diffuse granulomatous infiltrate with foamy histiocytes along with acid fast bacilli by Fite stain. By Ridley-Jopling classification system, three cases were diagnosis as lepromatous leprosy, and one, borderline lepromatous. Treatment included clofazimine, dapsone and rifampin that was offered free of charge by the National Hansen's Diseases Program, Baton Rouge, L.A. One patient did not tolerate therapy. In conclusion, a slowly progressive disseminated erythematous skin rash on the trunk should raise suspicion for leprosy in the elderly population in south MS.

Clinical Characteristics and Outcomes of Disseminated Strongyloidiasis in the United States-A Multicenter Network Analysis.

Human strongyloidiasis is a potentially life-threatening parasitic disease among immunocompromised hosts. We aim to determine the factors and mortality associated with disseminated strongyloidiasis. We conducted a U.S.-based multicenter retrospective cohort study to determine 90-day clinical outcomes for people diagnosed with Strongyloides infection in the TriNetX patient database. We identified adult patients with the International Classification of Diseases (10th revision, clinical modification) code for Strongyloides infection (B78) or a positive Strongyloides IgG antibody test and captured outcomes at 90 days. We identified 5,434 patients with strongyloidiasis, of whom 48 had disseminated strongyloidiasis for 0.9% prevalence of disseminated disease. Systemic connective tissue disorders, pulmonary eosinophilia, liver cirrhosis, blood disorders (monoclonal gammopathy, aplastic anemia, and lymphoid malignancy), malnutrition, alcohol use disorder, and transplantation status were frequent in patients with disseminated disease. Mortality was significantly higher in people with disseminated disease at 30 days (21%). The 90-day risk of hospitalization, bacteremia, and acute respiratory distress syndrome (ARDS) was higher in those with disseminated infection. People with disseminated strongyloidiasis had a heightened risk of hospitalization, bacteremia, acute respiratory distress syndrome, and mortality. The population at risk for severe strongyloidiasis infection is evolving, reflecting conditions in which glucocorticoids or additional immunosuppressive medications are commonly used for treatment.

Peromyscus leucopus , Mus musculus , and humans have distinct transcriptomic responses to larval Ixodes scapularis bites.

Ixodes scapularis ticks are an important vector for at least six tick-borne human pathogens, including the predominant North American Lyme disease spirochete Borrelia burgdorferi . The ability for these ticks to survive in nature is credited, in part, to their ability to feed on a variety of hosts without excessive activation of the proinflammatory branch of the vertebrate immune system. While the ability for nymphal ticks to feed on a variety of hosts has been well-documented, the host-parasite interactions between larval I. scapularis and different vertebrate hosts is relatively unexplored. Here we report on the changes in the vertebrate transcriptome present at the larval tick bite site using the natural I. scapularis host Peromyscus leucopus deermouse, a non-natural rodent host Mus musculus (BALB/c), and humans. We note substantially less evidence of activation of canonical proinflammatory pathways in P. leucopus compared to BALB/c mice and pronounced evidence of inflammation in humans. Pathway enrichment analyses revealed a particularly strong signature of interferon gamma, tumor necrosis factor, and interleukin 1 signaling at the BALB/c and human tick bite site. We also note that bite sites on BALB/c mice and humans, but not deermice, show activation of wound-healing pathways. These data provide molecular evidence of the coevolution between larval I. scapularis and P. leucopus as well as expand our overall understanding of I. scapularis feeding. Significance: Ixodes scapularis tick bites expose humans to numerous diseases in North America. While larval tick feeding enables pathogens to enter the tick population and eventually spread to humans, how larval ticks interact with mammals has been understudied compared to other tick stages. Here we examined the transcriptomic response of a natural I. scapularis rodent host ( Peromyscus leucopus ), a non-native I. scapularis rodent host ( Mus musculus ), and an incidental host (humans). We find that there are differences in how all three species respond to larval I. scapularis , with the natural host producing the smallest transcriptomic signature of a canonical proinflammatory immune response and the incidental human host producing the most robust signature of inflammation in response to the larval tick. These data expand our understanding of the pressures on ticks in the wild and inform our ability to model these interactions in laboratory settings.

Intestinal protozoan infections in the immunocompromised host.

PURPOSE OF REVIEW: Intestinal protozoa are becoming increasingly recognized as significant pathogens in immunocompromised hosts. However, pathogenesis of infection is still poorly understood, diagnostic tests remain insensitive, and management continues to pose a challenge. RECENT FINDINGS: Invasion by intestinal protozoa can be facilitated by impaired host T-cell immune response, although the exact pathogenesis at the cellular level is unclear. HIV-infected and transplant patients have been reported to have the highest risk for developing severe disease. Cryptosporidium is the most common parasite encountered in the immunocompromised host, followed by Cyclospora and Isospora. In recent years, Microsporidia and Blastocystis have also emerged as important players, due in part to improved molecular diagnostic assays. Effective drugs against these parasites in immunocompromised patients have not been reported in recent years. When possible, reducing the level of immunosuppression seems to be the most effective treatment strategy in combination with adjunctive antiparasitic therapy. SUMMARY: Despite that intestinal protozoan infections cause greater morbidity and mortality in the immunocompromised host, their pathogenesis in the setting of immunosuppression is poorly understood and efforts to develop new therapeutic agents are rather limited. Improving detection and identification of species or subtypes by PCR will result in improved management decisions and a better understanding of the epidemiology of intestinal protozoa. Favorable clinical outcomes can be achieved by early detection and effective treatment of the infection. Further research on key aspects of pathogenesis at the cellular level in humans is needed.

Relapsing Babesiosis With Molecular Evidence of Resistance to Certain Antimicrobials Commonly Used to Treat Babesia microti Infections.

Human babesiosis cases are emerging with an increased incidence and a wider geographic range worldwide. Relapsing babesiosis cases are becoming more frequently encountered in clinical practice associated with the use of immunosuppressive medications. The 2020 Infectious Diseases Society of America babesiosis guideline recommends at least 6 weeks of antimicrobial treatment for highly immunocompromised patients with Babesia microti infection. Nevertheless, cases have relapsed even after 6 weeks of treatment. Genetic mutations regarded as the potential cause of antimicrobial resistance in B microti have been identified in certain relapsing cases. A few alternative antimicrobial regimens have been used successfully to achieve cure for some of these cases, but other cases have had fatal outcomes. In this review, we discuss the molecular evidence of genetic resistance to certain antimicrobials commonly used to treat B microti infections based on an evaluation of 9 patients with relapsing infection.