Successful treatment with doxycycline monotherapy for human infection with Babesia venatorum (Babesiidae, Sporozoa) in China: a case report and proposal for a clinical regimen

Beyond Human Babesiosis: Prevalence and Association of Babesia Coinfection with Mortality in the United States, 2015-2022: A Retrospective Cohort Study

Background

The prevalence of Babesia coinfecting tick-borne zoonoses and mortality outcomes are not fully elucidated. The objective of the present study was to determine babesiosis coinfection prevalence rates and estimate the association with severe disease and mortality.

Methods

We queried the TriNetX database between 2015 and 2022 for patients with babesiosis. The prevalence of Babesia coinfecting tick-borne zoonoses was estimated. The analysis focused on babesiosis coinfection with Borrelia burgdorferi, ehrlichiosis, and anaplasmosis. The exposure was coinfection, and the control group was the Babesia-only group. The primary outcome was 90-day mortality from the diagnosis of Babesia. Secondary outcomes were prevalence of coinfection, association of coinfection with acute respiratory distress syndrome, multiorgan failure, and disseminated intravascular coagulation. A multivariable logistic regression model was employed to estimate the disease severity and mortality risk associated with coinfections.

Results

Of the 3521 patients infected with Babesia, the mean age (SD) was 56 (18) years, 51% were male, and 78% were White. The frequency of overall malignancies, lymphomas, and asplenia was 19%, 2%, and 2%, respectively. Temporal distribution of coinfections followed the overall babesiosis pattern, peaking in the summer months. The prevalence of 1 or more coinfections was 42% (95% CI, 40%-43%). The rate of coinfection with Borrelia burgdorferi was the highest at 41% (95% CI, 39%-42%), followed by ehrlichiosis at 3.7% (95% CI, 3.1%-4.4%) and anaplasmosis at only 0.3% (95% CI, 0.2%-0.6%). Doxycycline was more likely to be prescribed in the coinfection group than the Babesia-only group (25% vs 18%; P < .0001). Overall, 90-day mortality was 1.4% (95% CI, 1.0%-1.8%). After adjusting for potential confounding factors, compared with the babesiosis-only group, the likelihood of 90-day mortality was lower in the coinfection group (adjusted odds ratio, 0.43; 95% CI, 0.20-0.91). Severe disease did not differ significantly between the 2 groups.

Conclusions

In this extensive study of >3000 patients with babesiosis in the United States, 4 in 10 patients had coinfecting tick-borne zoonoses. The prevalence rates of coinfection were highest with Borrelia burgdorferi, followed by ehrlichiosis, and lowest with anaplasmosis. Coinfection with other tick-borne infections was not associated with severe disease. It is plausible that this finding is due to the likelihood of treatment of coinfections with doxycycline. Future studies are needed to investigate the possible therapeutic benefits of doxycycline in babesiosis patients as, to date, no trials with doxycycline have been conducted in human patients with Babesia infections.

Comparative genome-wide identification and characterization of SET domain-containing and JmjC domain-containing proteins in piroplasms

BACKGROUND

SET domain-containing histone lysine methyltransferases (HKMTs) and JmjC domain-containing histone demethylases (JHDMs) are essential for maintaining dynamic changes in histone methylation across parasite development and infection. However, information on the HKMTs and JHDMs in human pathogenic piroplasms, such as Babesia duncani and Babesia microti, and in veterinary important pathogens, including Babesia bigemina, Babesia bovis, Theileria annulata and Theileria parva, is limited.

RESULTS

A total of 38 putative KMTs and eight JHDMs were identified using a comparative genomics approach. Phylogenetic analysis revealed that the putative KMTs can be divided into eight subgroups, while the JHDMs belong to the JARID subfamily, except for BdJmjC1 (BdWA1_000016) and TpJmjC1 (Tp Muguga_02g00471) which cluster with JmjC domain only subfamily members. The motifs of SET and JmjC domains are highly conserved among piroplasm species. Interspecies collinearity analysis provided insight into the evolutionary duplication events of some SET domain and JmjC domain gene families. Moreover, relative gene expression analysis by RT‒qPCR demonstrated that the putative KMT and JHDM gene families were differentially expressed in different intraerythrocytic developmental stages of B. duncani, suggesting their role in Apicomplexa parasite development.

CONCLUSIONS

Our study provides a theoretical foundation and guidance for understanding the basic characteristics of several important piroplasm KMT and JHDM families and their biological roles in parasite differentiation.

New insights in the diagnosis and treatment of equine piroplasmosis: pitfalls, idiosyncrasies, and myths

Equine piroplasmosis (EP) is a global tick-borne disease of equids caused by the intraerythrocytic apicomplexan parasites Theileria equi and Babesia caballi, and the more recently discovered Theileria haneyi. These parasites can be transmitted by several tick species, including Dermacentor, Hyalomma, and Rhipicephalus, but iatrogenic and vertical transmission are also common. Clinical signs of EP include poor performance, fever, icterus, abortions, among others, and peracute or acute forms of infection are associated with high mortality in non-endemic areas. EP is a reportable disease and represents an important barrier for the international trade of horses and other equids, causing disruption of international equine sports. Tick control measures, serological and molecular diagnostic methods, and parasiticidal drugs are currently used against EP, while vaccines remain unavailable. Since most acaricides used in equids are non-environmentally friendly and linked to drug resistances, this is considered as an unsustainable approach. Imidocarb dipropionate (ID) and buparvaquone (BPQ) are currently the main drugs used to control the disease. However, while ID has several side and toxic effects and recurrent failures of treatment have been reported, BPQ is less effective in the clearance of T. equi infection and not available in some countries. Thus, novel alternative and effective therapeutics are needed. While current trade regulations require testing equids for EP before exportation, the lack of standardized PCR tests and limitations of the currently recommended serological assays entail a risk of inaccurate diagnosis. Hereby, we propose a combination of standardized PCR-based techniques and improved serological tests to diminish the risks of exporting EP-infected animals making equid international trade safer. In addition, this review discusses, based on scientific evidence, several idiosyncrasies, pitfalls and myths associated with EP, and identifies weaknesses of current methods of control and gaps of research, as initial steps toward developing novel strategies leading to control this disease.

Human Babesia odocoilei and Bartonella spp. co-infections in the Americas

BACKGROUND

In recent years, Babesia and Bartonella species co-infections in patients with chronic, nonspecific illnesses have continued to challenge and change the collective medical understanding of "individual pathogen" vector-borne infectious disease dynamics, pathogenesis and epidemiology. The objective of this case series is to provide additional molecular documentation of Babesia odocoilei infection in humans in the Americas and to emphasize the potential for co-infection with a Bartonella species.

METHODS

The development of improved and more sensitive molecular diagnostic techniques, as confirmatory methods to assess active infection, has provided increasing clarity to the healthcare community.

RESULTS

Using a combination of different molecular diagnostic approaches, infection with Babesia odocoilei was confirmed in seven people suffering chronic non-specific symptoms, of whom six were co-infected with one or more Bartonella species.

CONCLUSIONS

We conclude that infection with Babesia odocoilei is more frequent than previously documented and can occur in association with co-infection with Bartonella spp.

Repeated imidocarb treatment failure suggesting emerging resistance of Babesia canis in a new endemic area in north-eastern Germany

Canine babesiosis has been increasingly diagnosed in various regions of Germany such as north-eastern Germany in recent years. A dog with several relapses of Babesia canis infection after treatment with imidocarb is described. A 9-year-old male Magyar Viszla with B. canis infection was referred after two treatments with imidocarb (dosage 2.1 mg/kg SC) because of lethargy, fever and pancytopenia (additional treatments with prednisolone and doxycycline). Merozoites were detected in the blood smear and imidocarb treatment was repeated. Clinical signs, pancytopenia and a positive B. canis PCR occurred after the 3rd (6 mg/kg SC), 4th (7.7 mg/kg SC) and 5th (7.5 mg/kg SC and doxycycline for 4 weeks in addition) imidocarb injection and thorough tick prevention with isoxazoline and permethrin products. 12 days after the 5th injection, the PCR was negative for the first time. The dog was again presented with fever 35 days after the 5th injection. The B. canis PCR was positive and laboratory examination revealed pancytopenia. Treatment with atovaquone/azithromycin for 18 days was performed and no further relapse occurred for 32 weeks. In the case of suspected imidocarb resistance in B. canis infection, treatment with atovaquone/azithromycin can be an alternative.