Fatal experimental transplacental Babesia gibsoni infections in dogs

A Babesia gibsoni infected bitch was mated with an uninfected dog in order to determine whether this parasite could be vertically transmitted. The bitch delivered a litter of four live and one stillborn pup. The four pups died from congenital babesiosis between 14 and 39 days post-birth. Babesia gibsoni DNA was detected in tissue from all five pups. These results show that vertical transmission occurred by the uterine route and not via the transmammary route. This is the first confirmed report of transplacental Babesia infection in any animal species.

European strategies against the parasite transfusion risk

Protozoal infections are endemic in mainly tropical low income countries, affecting millions of people. Malaria, American trypanosomiasis (Trypanosoma cruzi/Chagas disease) and protozoal tickborne diseases (e.g. Babesia) can be efficiently transmitted by transfusion of cellular blood components. In non-endemic areas like Europe malaria, Chagas disease and Babesia are imported diseases resulting of travelling to endemic areas and migration of autochthons from these endemic areas. A recent International Forum showed that in Europe, as well as the USA, prevention of transfusion-associated protozoal infections depend mainly on selection of donors using questionnaires. Most countries divide donors at risk for malaria in two groups: individuals who have lived in the first 5 years of their life in malaria endemic areas and those who are borne and residing in non-endemic areas and visited the endemic area(s). The first category of donors is rejected for 3 years after their last visit to the endemic area, and in one country such donors are permanently rejected. In some countries such donors are accepted after 4 months-3 years, provided a test for malaria is non-reactive. Persons from non-endemic areas, who visited the malaria endemic area, are rejected for 4-12 months. Some countries reject these donors for 3 years or permanently when they resided for more than 6 months in the endemic area. The rejection rate of donors for malaria risk in the various countries was 0.003-0.43% of all donations. Over the last decade only a few cases of TT-malaria were reported in the various countries. In several countries donors are questioned for risk of T. cruzi infection. In some countries donors are excluded when they (or their mothers) were born in South or Central America, if they received a blood transfusion in these areas and if they lived in rural areas in these endemic countries for more than 4 weeks. In none of the countries donors are asked if they had Babesia or Leishmania. At present implemented measures to prevent TT-malaria in the European countries are probably highly effective. More research is needed to establish the theoretical risk of TT-T. cruzi and TT-Leishmania infection in Europe, before preventive measures may be considered.

Lyme disease and babesiosis: preliminary findings on the transmission risk in highly frequented areas of the Monti Sibillini National Park (Central Italy)

The Monti Sibillini National Park is a recently borne protected area in the central Apennines that has become an important tourist destination. Mountain grasslands and woods have made it also a suitable habitat for sheep and bovine cattle, as well as for wild animals such as the wild bore and the roe deer. Therefore, a preliminary investigation was conducted to assess the risk of transmission of tick-borne zoonoses, such as Lyme disease and Babesiosis, by actively looking for both the arthropod vector and the causative agent. For two consecutive years, ambushing ticks were collected in four distinct geographical areas, comprehensive of many highly frequented tourist places. The tick fauna, tick habitats and the seasonal distribution of the different tick life stages collected with the method of "flagging and dragging" have been reported. Almost all the collected specimens belonged to the species Haemaphysalis punctata (Canestrini and Fanzago) (Acari: Ixodidae), which was found moderately infected with Babesia spp. Only a few Ixodes ricinus (Linnaeus) ticks, the most competent vector of Lyme disease, were found and on PCR examination all of them resulted negative as far as the infectious agent Borrelia burgdorferi sensu lato (Johnson) is concerned.

[Autochthonous babesiosis in dogs in The Netherlands associated with local Dermacentor reticulatus ticks]

In the spring and autumn of 2004, 20 respectively 3 cases of autochthonous canine babesiosis were diagnosed in the Netherlands, four of which ended fatally. Adult Dermacentor reticulatus ticks were found on four dogs. Case descriptions and diagnostics of this B. canis outbreak are discussed in more detail.

Molecular Characterization of Human Pathogen Babesia EU1 in Ixodes ricinus Ticks From Slovenia

New cases of human babesiosis were recently reported in Europe. The etiological agent was identified as Babesia EU1, a zoonotic pathogen with previously unreported molecular characteristics. On the basis of a comparison of the complete babesial 18S rRNA gene, we have generated strong molecular evidence that Ixodes ricinus ticks from Slovenia are infected with EU1.

Evidence of Bartonella sp. in questing adult and nymphal Ixodes ricinus ticks from France and co-infection with Borrelia burgdorferi sensu lato and Babesia sp

Ticks are known vectors for a wide range of pathogenic microorganisms. Their role in the transmission of some others is so far only suspected. Ticks can transmit multiple pathogens, however, little is known about the co-existence of these pathogens within questing ticks. We looked for the presence of DNA from three micro-organisms, Bartonella sp., Borrelia burgdorferi sensu lato and Babesia sp. which are known or suspected tick-borne pathogens, using a cohort of 92 questing Ixodes ricinus ticks collected from pastures in northern France. DNA was extracted from each individual tick and the presence of the three pathogens was investigated using Polymerase Chain Reaction (PCR) amplification. Nine among 92 samples (9.8%) demonstrated PCR products using Bartonella specific primers, 3 among 92 (3.3%) using Borrelia burgdorferi sensu lato specific primers and 19 among 92 (20.6%) using Babesia specific primers. Seven among 92 samples (7.6%) were PCR positive for at least two of the pathogens and one sample was positive for all three. Adult ticks (12/18; 67%) showed significantly higher infection rates compared to nymphs (11/74; 15%) for all three pathogens (P < 0.001). This study is the demonstration of the simultaneous presence of Bartonella sp., Borrelia burgdorferi sensu lato and Babesia sp. in questing Ixodes ricinus ticks.

Reduced Incidence ofBabesia bigeminaInfection in Cattle Immunized against the Cattle Tick,Boophilus microplus

Boophilus microplus is an important vector of bovine disease agents having a major economic impact on cattle production in many tropical and subtropical countries. Components of tick saliva that enable ticks to feed may also facilitate establishment of tick-borne pathogens in the vertebrate host. It has been suggested that acquired resistance against molecules in tick saliva could inhibit parasite transmission, and there is increasing evidence to support this hypothesis. The effect of immune resistance to B. microplus on the incidence of tick-transmitted pathogens was the focus of this experiment. Groups of four dairy cows were injected with antigen extracts of tick salivary glands, midgut, adjuvant only, or PBS, prior to a grazing period in a pasture in Thailand where ticks are abundant and babesiosis is enzootic. These animals were then observed for evidence of babesiosis throughout the rainy season. A reduction in the incidence of clinical babesiosis was observed among cattle immunized with salivary gland preparations compared to nonimmunized controls (P < 0.05). Immunization with midgut or adjuvant only both resulted in a slight reduction in observed disease compared to the same negative control group. B. bigemina was detected in fewer ticks (24.43%) collected from salivary gland-immunized cattle than those collected from the remaining groups (> or =44.57%). These results indicated that immunization with salivary gland antigens could affect pathogen transmission and appears promising for control of tick-borne diseases of cattle.

Babesia bigemina sexual stages are induced in vitro and are specifically recognized by antibodies in the midgut of infected Boophilus microplus ticks

Babesia bigemina, a causative agent of bovine babesiosis, is transmitted from one bovine to another only by infected ticks. The life cycle of B. bigemina includes a sexual phase in the tick host; however, molecules from sexual stages of any Babesia species have not been characterized. This is the first report of the induction of sexual stages of any Babesia species in vitro, free of tick antigens. Intraerythrocytic parasites were cultured in vitro for 20h using an induction medium. Extraerythrocytic parasites were first seen 3h post induction; elongated stages with long projections appeared at 6h post induction and by 9h they paired and fused to form larger stages. Round zygotes appeared 20h post induction. Moreover, by using Percoll gradients, sexual stages were purified free of contaminating intraerythrocytic stages. Purified parasites were used to generate polyclonal antibodies, which specifically bound to antigens expressed in sexual stages induced in vitro, but not to antigens expressed in intraerythrocytic stages. Importantly, these antibodies specifically identified sexual stages from midguts of female Boophilus microplus ticks fed on infected cattle.

Survey of rodents and ticks in human babesiosis emergence area in Japan: first detection of Babesia microti-like parasites in Ixodes ovatus

Babesia microti-like parasites were detected for the first time in Ixodes ovatus in Hyogo Prefecture, Japan, where two reported types of B. microti-like parasites were recognized in many rodents. Of 80 adult I. ovatus ticks collected, 5 possessed the reported type and 1 possessed a new type of B. microti-like parasite.

Risk and prevention of transfusion-transmitted babesiosis and other tick-borne diseases

PURPOSE OF REVIEW

Tick-borne diseases have increasingly been recognized in the United States as public health problems. The importance of tick-borne diseases has been accelerated by increases in animal populations, as well as increased human recreation in wooded environments that are conducive to tick bites. Babesiosis, usually caused by the intraerythrocytic parasite, Babesia microti and transmitted by the same tick as Lyme disease, has important transfusion implications. Although Lyme disease has not been reported from blood transfusion, newly identified tick-borne diseases such as ehrlichiosis raise additional questions about the role of the tick in transfusion-transmitted diseases.

RECENT FINDINGS

The risk of transfusion-transmitted babesiosis is higher than usually appreciated and in endemic areas represents a major threat to the blood supply. Furthermore, the geographic range of B. microti is expanding, other Babesia spp. have been implicated in transfusion transmission in the western United States, and the movement of blood donors and donated blood components may result in the appearance of transfusion babesiosis in areas less familiar with these parasites. Consequently, a higher degree of clinical suspicion will allow early recognition and treatment of this important transfusion complication.

SUMMARY

In endemic areas transfusion-transmitted babesiosis is more prevalent than usually believed. The extension of the geographic range of various Babesia spp. and the movement of donors and blood products around the United States has resulted in the risk extending to non-endemic areas. Clinicians should maintain a high degree of clinical suspicion for transfusion-transmitted babesiosis.

[Tick borne zoonosis: selected clinical and diagnostic aspects]

Tick-borne zoonotic infections are among the most diffuse vector borne diseases: these large group of infections is caused by different microorganisms: Babesia spp., Borrelia spp., Rickettsia spp., Ehrlichia spp., Francisella tularensis, Coxiella burnetii) and tick-borne encephalitis virus. Babesiosis is caused by the protozoa (sporozoa) Babesia microti and it is quite rare in humans in Europe. The ixodids ticks are the competent vectors. A few symptomatic cases have been reported, mainly in splenectomized patients. The laboratory diagnosis is made by the microscopic identification of the parasites within the red blood cells in blood smears. The serologic diagnosis, based mainly upon IFA and WB techniques has only an epidemiological interest. Lyme borreliosis (Lyme disease) has been recognized as the most frequent vector borne disease in mild climate areas. The etiologic agent is a spirochete, belonging to the Borrelia burgdorferi sensu lato complex: B. burgdorferi sensu stricto, B. garinii and B. afzelii. Several additional species of this geno-complex have been identified but their pathogenic capability for humans still needs to be elucidated. Lyme borreliosis is clinically divided into three different clinical stages: the early disease, the disseminated infection and the persistent infection. Individual stages are caused by the diffusion of the spirochetes to different anatomic districts of the body. The main clinical symptoms are, for each stage: the erythema chronicum migrans in the early infection, the peripheral nerves and joint involvement in disseminated diseases and the acrodermatitis chronica atrophica (ACA) with central nervous system involvement in the late disseminated infection. The microbiological diagnosis is achieved by serologic techniques (IFA, EIA, WB) and by isolation of the spirochetes (in vitro culture and DNA amplification methods). Tick-borne relapsing fever (TBRF) is occasionally transmitted to humans by the soft ticks Ornithodorus and is caused by Borrelia spp. Different borreliae are responsible for TBRF in various geographic areas. The laboratory diagnosis is based upon the identification of spirochetes in peripheral blood by microscopic observation of Giemsa stained smears. Rickettsiosis diseases are caused worldwide by the obligate intracellular bacteria belonging to the genus Rickettsia. In the Mediterranean area the most frequently identified rickettsia is R. conorii, that causes the so called Mediterranean spotted fever. The serologic detection of a specific antibody response by IFA techniques is the most prominent tool for the diagnosis. In addition, the PCR method can be applied. Bacteria of the genus Ehrlichia are well known pathogens in veterinary medicine. Since the last decade their zoonotic capability has emerged and E. chafeensis, E. canis and the so called human granulocytic agent (HGE) have been identified in human diseases following a tick bite. The ehrlichiosis is characterized, in human, by a mild fever associated with lymphoadenopathy. The diagnosis is made on the identification of morulae (the intracytoplasmatic inclusion of the growing rickettsiae) in the white cells of peripheral blood. In addition the molecular diagnosis is also possible by PCR. Tick-borne encephalitis (TBE) is the only viral arthropod-borne encephalitis in Europe: it is caused by a flavivirus and it can also be transmitted by the ingestion of goat raw milk. The more relevant epidemiological figure is limited to the Alps, in particular to the Northern side (Austria). Isolated cases have been reported also in Italy. TBE is a benign self-limiting illness that usually recovers without any reliquate. The laboratory diagnosis is obtained by isolating the virus in cell cultures from the CSF or blood of acute phase patients. Serology is anyway the main laboratory tool to perform this diagnosis. Complement fixation and EIA IgM are the most used methods: the latter technique is particularly sensitive in early infection.

Infection and blood transfusion: a guide to donor screening

In recent years, blood-component therapy has become more accessible in veterinary practice. As with human medicine, care must be taken to minimize the risk of disease transmission from donor to recipient. Determining the appropriate diseases to screen for is complicated by regional variations in disease incidence, the existence of chronic carrier states for some diseases, the difficulty in screening-test selection, and testing cost. The feline diseases considered include retroviral infections, feline coronaviruses, ehrlichiosis (Ehrlichia canis-like), anaplasmosis (Anaplasma phagocytophilum), neorickettsiosis (Neorickettsia risticii), hemoplasmosis (Mycoplasma hemofelis and M. hemominutum, previously feline hemobartonellosis), and cytauxzoonosis (Cytauxzoon felis). The canine diseases considered in this paper include babesiosis (Babesia canis and B. gibsonii,) ehrlichiosis (E. canis and E. ewingii), anaplasmosis (A. phagocytophilum), neorickettsiosis (N. risticii var. atypicalis), leishmaniasis (Leishmania donovani complex), brucellosis (Brucella canis), hemoplasmosis (M. hemocanis, previously canine hemobartonellosis), and bartonellosis (Bartonella vinsonii).

Experimental transmission of an unnamed bovine Babesia by Hyalomma spp., Haemaphysalis longicornis and Boophilus microplus

Experiments were undertaken to determine the mode of transmission to cattle of an unnamed Babesia sp. by Hyalomma anatolicum anatolicum, Hyalomma detritum, Hy. rufipes koch, Haemaphysalis longicornis and Boophilus microplus. The unnamed Babesia species designated Babesia U sp. was isolated by infesting cattle with nymphs from female Hy. a. anatolicum ticks collected from Xinjiang province. Adults of laboratory reared Hy. a. anatolicum, Hy. detritum and Hy. rufipes koch were infected with Babesia U sp. by feeding on infected cattle, isolated with nymphal ticks of Hy. a. anatolicum derived from females collected from field. The experiments revealed that Hy. a. anatolicum was capable of transmitting Babesia U sp. transovarially in larval (2 of 4 calves), nymphal (6 of 6 calves) and adult (3 of 8 calves) stages, with prepatent periods of 16, 12, and 8 days, respectively, and that this Babesia was also transovarially transmitted by both the nymphal and adult stages of Hy. detritum and Hy. rufipes. Attempts to transmit this Babesia U sp. transovarially with Hae. longicornis and B. microplus, and transstadially with Hyalomma spp., were carried out, and the results proved to be negative.

Ribosomal RNA analysis of Babesia odocoilei isolates from farmed reindeer ( Rangifer tarandus tarandus ) and elk ( Cervus elaphus canadensis ) in Wisconsin

Piroplasms isolated from a farmed reindeer and elk in Wisconsin were determined to be Babesia odocoilei, based on morphology and ribosomal RNA (rRNA) analysis. Different clinical manifestations were observed in the two host species. The reindeer was parasitemic and exhibited acute babesiosis resulting in death, while the elk showed no parasites in blood smears and no overt clinical signs of babesiosis. B. odocoilei was, however, readily cultured from elk erythrocytes. Small subunit rRNA gene sequences from the two isolates were identical to that previously reported for B. odocoilei. Internal transcribed spacers 1 and 2 and 5.8S rRNA sequence analysis showed an overall identity range of 94.3-98.1% to corresponding sequences from three previously reported B. odocoilei isolates, but the Wisconsin reindeer B. odocoilei shared only 87.3% identity with a previously reported Babesia sp. isolated from a reindeer in California (RD61).

Vector-borne illnesses and the safety of the blood supply

The protection of patients from diseases carried in blood transfusions is an ongoing effort. The viruses that cause long-term human infection and death have received much of the attention in the United States and testing has significantly diminished the risk of infection from a transfusion. As the risk of these diseases has decreased, other transfusion-transmitted organisms with a lower incidence in the community or newer diseases with rapidly expanding endemic areas are receiving additional attention. One group of these infections are infections in which the normal route of human infection is a vector.

Enzootic transmission of Babesia divergens among cottontail rabbits on Nantucket Island, Massachusetts

Specific ticks seem to locally serve as vector for characteristic microbial assemblages (guilds) comprising spirochetes, piroplasms, ehrlichiae, and arboviruses. Borrelia andersoni and Anaplasma phagocytophilum are intensely transmitted between cottontail rabbits. To test the hypothesis that a piroplasm may also be maintained in rabbits, we sampled these hosts from Nantucket Island, Massachusetts and tested their blood and tissues by a polymerase chain reaction for evidence of infection. Surprisingly, the agent of bovine redwater and of European human babesiosis, Babesia divergens, was detected in 16% of the rabbits sampled during 1998-2002 (> 99% sequence similarity in the 18S ribosomal DNA). The vector of B. divergens on Nantucket appears to be Ixodes dentatus, a rabbit- and bird-feeding tick that may feed on humans. Although the risk of human infection appears to be minimal, an autochthonously acquired Kentucky case due to this rabbit agent was recently reported. Physicians should entertain the diagnosis of babesiosis due to B. divergens for severe hemolytic febrile syndromes in American patients exposed to sites where rabbits are common.

PCR-based detection of the transovarial transmission of Uruguayan Babesia bovis and Babesia bigemina vaccine strains

Bovine babesiosis is responsible for serious economic losses in Uruguay. Haemovaccines play an important role in disease prevention, but concern has been raised about their use. It is feared that the attenuated Babesia bovis and Babesia bigemina vaccine strains may be transmitted by the local tick vector Boophilus microplus, and that reversion to virulence could occur. We therefore investigated the possibility that these strains could be transmitted via the transovarial route in ticks using a Babesia species-specific polymerase chain reaction (PCR) assay. DNA was extracted from the developmental stages of the tick vector that had fed on calves immunized with the haemovaccine. It was possible to detect Babesia DNA not only in adult ticks, but also in their eggs and larvae. In addition, it was shown that calves infested with larvae derived from eggs laid by ticks fed on acutely infected calves, were positive for Babesia using PCR. Caution should therefore be shown with the distribution of the haemovaccine in marginal areas. It is still advisable that suitable tick control measures be used to prevent transovarial transmission and the potential risk of attenuated Babesia reverting to virulence.

The innate immune response in calves to Boophilus microplus tick transmitted Babesia bovis involves type-1 cytokine induction and NK-like cells in the spleen

The innate immune response to Babesia bovis infection in cattle is age-related, spleen-dependent and, in stabilate inoculated calves, has type-1 characteristics, including the early induction of IL-12 and IFN-gamma. In this study with three calves, parameters of innate immunity were followed for 2 weeks after tick transmission of B. bovis. Each calf survived the acute disease episode without drug intervention, and responded with increased levels of plasma interferon-gamma and type-1 cytokine expression, monocyte/macrophage activation, and CD8+ cellular proliferation in the spleen. The proliferating CD8+ population consisted primarily of NK-like cells, and the expansion occurred in parallel with an increase in IL-15 mRNA expression in the spleen.