Human Babesiosis Caused by Babesia duncani Has Widespread Distribution across Canada

Abstract

Human babesiosis caused by Babesia duncani is an emerging infectious disease in Canada. This malaria-like illness is brought about by a protozoan parasite infecting red blood cells. Currently, controversy surrounds which tick species are vectors of B. duncani. Since the availability of a serological or molecular test in Canada for B. duncani has been limited, we conducted a seven-year surveillance study (2011–2017) to ascertain the occurrence and geographic distribution of B. duncani infection country-wide. Surveillance case data for human B. duncani infections were collected by contacting physicians and naturopathic physicians in the United States and Canada who specialize in tick-borne diseases. During the seven-year period, 1119 cases were identified. The presence of B. duncani infections was widespread across Canada, with the highest occurrence in the Pacific coast region. Patients with human babesiosis may be asymptomatic, but as this parasitemia progresses, symptoms range from mild to fatal. Donors of blood, plasma, living tissues, and organs may unknowingly be infected with this piroplasm and are contributing to the spread of this zoonosis. Our data show that greater awareness of human babesiosis is needed in Canada, and the imminent threat to the security of the Canadian blood supply warrants further investigation. Based on our epidemiological findings, human babesiosis should be a nationally notifiable disease in Canada. Whenever a patient has a tick bite, health practitioners must watch for B. duncani infections, and include human babesiosis in their differential diagnosis.

Establishment of a continuous in vitro culture of Babesia duncani in human erythrocytes reveals unusually high tolerance to recommended therapies

“…Babesia microti, Babesia duncani, and Babesia divergens are responsible for most cases of babesiosis world-wide (1). Whereas B. microti is endemic in the Northeastern and Midwestern regions of the United States, and has further been reported worldwide, all confirmed cases of B. duncani have been found primarily in the Western United States (2,3). A recent report based on available serological and/or molecular tests has suggested that B. duncani is also widespread in Canada (2,3).…”

“…Whereas B. microti is endemic in the Northeastern and Midwestern regions of the United States, and has further been reported worldwide, all confirmed cases of B. duncani have been found primarily in the Western United States (2,3). A recent report based on available serological and/or molecular tests has suggested that B. duncani is also widespread in Canada (2,3). On the other hand, cases of babesiosis in humans caused by B. divergens have so far been primarily reported in Europe, with some B. divergens-like cases reported in Japan and the United States (4,5).…”

Combined Immunofluorescence (IFA) and Fluorescence In Situ Hybridization (FISH) Assays for Diagnosing Babesiosis in Patients from the USA, Europe and Australia

“…Other recent IFA data also suggest that B. duncani is more widespread in the USA [ 28 , 31 , 34 ] than previously recognized [ 5 , 7 , 22 ]. Human babesiosis caused by B. duncani has also been recently found to be widely distributed in Canada [ 8 ]. While the occurrence of human babesiosis had not been extensively studied in Australia, there is evidence suggesting the indigenous transmission of B. duncani and B. microti in Australia [ 35 ].…”

“…Human to human transmission of Babesia species can occur through blood transfusion, congenital transmission and organ transplantation [ 3 , 4 , 6 ]. Babesia microti , B. duncani and B. divergens are mainly responsible for human babesiosis in the USA [ 2 , 3 , 4 ] with B. microti and B. duncani considered to be, respectively, more prevalent in the East and West coasts of North America [ 5 , 7 , 8 ]. Babesia microti , B. divergens , B. venatorum and B. crassa are responsible for babesiosis in Eurasia [ 2 , 3 ].…”

Fatal Human Babesiosis in a Nine-Year Old Nigerian Girl

“…Babesia microti and B. duncani [8] are the commonly reported species causing human babesiosis and the infection is confirmed by identification of the organism on Giemsa or Wright's stained blood smears, showing intraerythrocytic tetrads of merozoites, arranged in 'maltese cross' pattern. This appearance is pathognomonic of babesial infection.…”