this case represents the first report of a novel hemoplasma species in a human in association with doxycycline - responsive pyrexia , hemolytic anemia , and a history of chronic moderate neutropenia . candidatus mycoplasma haemohominis  is proposed for this novel organism should further characterization be possible . this case is unique in several ways : first in describing human infection with a novel hemoplasma species that is distinct from described veterinary hemoplasma species , second in associating human hemoplasma infection with clinically significant hemolysis , and third in the use of qpcr to quantify hemoplasma dna in human diagnostic samples and thus monitor response to treatment . diagnosis of hemoplasma infection in this patient was based on pcr analysis of bone marrow  derived dna , but peripheral blood samples could have been an alternative source of dna for diagnosis , as performed in veterinary practice . human hemoplasma - like infections have been reported occasionally in immunocompromised patients by means of cytological diagnosis , which is known to be very unreliable [ 1 , 3 ] . although human hemoplasma infections have been reported in china [ 5 , 6 ] , these descriptions have not described clinical disease , pcr methodology , or infecting species , making interpretation difficult . other studies have described the presence of existing veterinary hemoplasma species dna in humans : mycoplasma suis [ 7 , 8 ] , mycoplasma haemofelis and/or mycoplasma haemocanis [ 9 , 10 ] , and mycoplasma ovis . however , any association between hemoplasma infection and clinical signs in these reports is difficult to ascertain due to either lack of clinical information provided [ 7 , 8 , 10 ] or concurrent b. henselae infection [ 9 , 11 ] . it is unlikely that co - infection with bartonella spp was present in this case due to the negative serological and pcr results for bartonella spp obtained and the fact that only hemoplasma dna was detected by 16s rdna pcr . it is possible that the patient s neutropenia played a role in the initial development of clinical hemoplasmosis through immunocompromise . it is less likely that a chronic hemoplasma infection played a role in causing neutropenia , as evidenced by the long history of neutropenia prior to any illness and return to low wbc counts with effective treatment and clearance of infection on specific qpcr , but this remains a possibility . it is possible that it represents a zoonotic infection acquired , for example , from blood - sucking arthropods such as ticks , fleas , and lice   or by direct transmission from another mammalian host through parenteral or oral inoculation of blood , but no such transmission events were recalled by the patient before onset of disease . it is possible that this novel hemoplasma represents a species of which the primary host is humans . hemoplasma infections exist in veterinary species in both the united kingdom and australia so transmission could have occurred before , during , or after the patient s vacation . besides the patient s husband and pet dog ( both of which were tested for hemoplasma dna ) there was no other significant animal or mammal contact reported . as described elsewhere for veterinary hemoplasma infections , the patient described here showed a remarkable clinical response to doxycycline . subsequently , a 6-month course of doxycycline and moxifloxacin was associated with negative qpcr results for hemoplasma dna , and the patient then remained qpcr negative following cessation of treatment . the low levels of hemoplasma dna detected by qpcr at some time points during doxycycline and moxifloxacin treatment could reflect amplification of nonviable hemoplasma dna that had not been cleared from the circulation , although in animal studies rapid clearance of hemoplasma dna from the circulation is usually reported following effective antibiotic treatment . in conclusion , hemoplasmosis should be considered as a differential diagnosis in patients with hemolytic anemia and pyrexia . pcr testing for hemoplasma dna should be included in the investigation of such patients to enable the rapid detection of this infection , which may be more common than previously realized . this case represents the first report of a novel hemoplasma species in a human in association with doxycycline - responsive pyrexia , hemolytic anemia , and a history of chronic moderate neutropenia . candidatus mycoplasma haemohominis  is proposed for this novel organism should further characterization be possible . this case is unique in several ways : first in describing human infection with a novel hemoplasma species that is distinct from described veterinary hemoplasma species , second in associating human hemoplasma infection with clinically significant hemolysis , and third in the use of qpcr to quantify hemoplasma dna in human diagnostic samples and thus monitor response to treatment . diagnosis of hemoplasma infection in this patient was based on pcr analysis of bone marrow  derived dna , but peripheral blood samples could have been an alternative source of dna for diagnosis , as performed in veterinary practice . human hemoplasma - like infections have been reported occasionally in immunocompromised patients by means of cytological diagnosis , which is known to be very unreliable [ 1 , 3 ] . although human hemoplasma infections have been reported in china [ 5 , 6 ] , these descriptions have not described clinical disease , pcr methodology , or infecting species , making interpretation difficult . other studies have described the presence of existing veterinary hemoplasma species dna in humans : mycoplasma suis [ 7 , 8 ] , mycoplasma haemofelis and/or mycoplasma haemocanis [ 9 , 10 ] , and mycoplasma ovis . however , any association between hemoplasma infection and clinical signs in these reports is difficult to ascertain due to either lack of clinical information provided [ 7 , 8 , 10 ] or concurrent b. henselae infection [ 9 , 11 ] . it is unlikely that co - infection with bartonella spp was present in this case due to the negative serological and pcr results for bartonella spp obtained and the fact that only hemoplasma dna was detected by 16s rdna pcr . it is possible that the patient s neutropenia played a role in the initial development of clinical hemoplasmosis through immunocompromise . it is less likely that a chronic hemoplasma infection played a role in causing neutropenia , as evidenced by the long history of neutropenia prior to any illness and return to low wbc counts with effective treatment and clearance of infection on specific qpcr , but this remains a possibility . it is possible that it represents a zoonotic infection acquired , for example , from blood - sucking arthropods such as ticks , fleas , and lice   or by direct transmission from another mammalian host through parenteral or oral inoculation of blood , but no such transmission events were recalled by the patient before onset of disease . it is possible that this novel hemoplasma represents a species of which the primary host is humans . hemoplasma infections exist in veterinary species in both the united kingdom and australia so transmission could have occurred before , during , or after the patient s vacation . besides the patient s husband and pet dog ( both of which were tested for hemoplasma dna ) there was no other significant animal or mammal contact reported . as described elsewhere for veterinary hemoplasma infections , the patient described here showed a remarkable clinical response to doxycycline . subsequently , a 6-month course of doxycycline and moxifloxacin was associated with negative qpcr results for hemoplasma dna , and the patient then remained qpcr negative following cessation of treatment . the low levels of hemoplasma dna detected by qpcr at some time points during doxycycline and moxifloxacin treatment could reflect amplification of nonviable hemoplasma dna that had not been cleared from the circulation , although in animal studies rapid clearance of hemoplasma dna from the circulation is usually reported following effective antibiotic treatment . in conclusion , hemoplasmosis should be considered as a differential diagnosis in patients with hemolytic anemia and pyrexia . pcr testing for hemoplasma dna should be included in the investigation of such patients to enable the rapid detection of this infection , which may be more common than previously realized . ethics approval from the university of bristol was obtained for analysis of the human samples . we thank hal neimark and chris helps for helpful discussions during the preparation of this manuscript , and sarinder day , daniel thomas , and andre buckeridge for technical support . this work was supported by the wellcome trust ( grant 077718 ) ; the university of bristol ( postgraduate research scholarship to e. n. b. ) ; and pfizer animal health ( support for e. n. b. ) . conflicts that the editors consider relevant to the content of the manuscript have been disclosed .