First detection of “Candidatus Mycoplasma haemolamae” in alpaca (Vicugna pacos) in Italy

Objective: Candidatus Mycoplasma haemolamae is a wall-less hemotropic prokaryote that infects camelids. To the author's knowledge, there have been no published reports of Candidatus M. haemolamae infection in alpacas in Italy. This study describes a clinical case of Candidatus M. haemolamae infection in an alpaca cria from northern Italy and the prevalence in its herd. Materials and methods: A 2 month-old alpaca cria was referred to the Clinic for Ruminants of the Veterinary Teaching Hospital of the University of Milan for weakness and lethargy. At birth, the alpaca cria was immediately rejected by their dam and fed with artificial bovine colostrum (Locatim®, Boehringer Ingelheim, Germany) and pasteurized whole cow's milk. At admission, the cria presented pale mucosae, tachycardia, and moderate dehydration. The hemogasanalysis underlined severe hypoglycaemia (1.1 mmol/L) and anaemia (haematocrit 17%, haemoglobin 5.6 g/dl). The complete blood count (CBC) confirmed mild, regenerative anaemia. The blood smear revealed numerous small basophilic coccoid structures attached to the surface of erythrocytes compatible with Candidatus M. haemolamae infection. In addition, parasitology examination of the faeces revealed severe coccidian infestation. To confirm the presence of Candidatus M. haemolamae, a portion of the 16S rRNA gene was amplified using a species-specific real-time PCR on blood samples collected at day of admission and at day of discharge. Threshold cycle (Ct) number was used as the measure of bacterial load (the lower the Ct level the greater the amount of target nucleic acid is present in the sample). Subsequently, the other animals of the entire herd from which the primary case was detected were tested by real-time PCR and by blood smear examination to investigate the presence of Candidatus M. haemolamae (n=20). Results: In the blood sample collected at admission, real-time PCR revealed a high level of Candidatus M. haemolamae DNA (Ct 11.7). The cria was stabilized by administration of a 10% glucose solution, iron dextran (5 mg/kg, subcutaneously once), B vitamins (10 mg/kg, subcutaneously once), E vitamins, and selenium (0.05 mg/kg, subcutaneously once). Furthermore, the animal was treated with long acting oxytetracycline (20 mg/kg, subcutaneously, q72h for 3 treatments) for the Candidatus M. haemolamae infection. By the third day of hospitalization, the animal's clinical condition had improved. Eight days after hospitalization, the haematocrit (30.1%) and haemoglobin (11.7 g/dl) were also within the reference ranges, and the alpaca was discharged. The blood smear, performed on the day of discharge, did not show the presence of Candidatus M. haemolamae whereas real-time PCR was still positive, showing lower DNA levels (Ct 24.7) compared to the first blood sample. Anticoccidial therapy was set at discharge with sulfadimethoxine (110 mg/kg, orally, q 24 h for 10 days). A 65% (13/20) Candidatus M. haemolamae real-time PCR positivity was reported in the other animals of the herd, with Ct values ranging from 16.4 to 32. A poor agreement between PCR result and smear examination was observed. The dam of the cria showed positive molecular results. An overall 66.7% (14/21) prevalence was observed in the herd, including the alpaca cria. No animal other than the cria had clinical manifestations correlated to the infection. Conclusion: This study reports the first identification of Candidatus M. haemolamae in Italy. As shown in other studies, clinical infection was observed in a young animal, and further parasitic infestations (such as coccidiosis) were associated with Candidatus M. hemolamae infection. Treatment with oxytetracycline during Candidatus M. hemolamae infection was valid only for symptom remission, but the alpaca cria continued to be PCR positive after treatment, in accordance with previous observations on treatment in positive alpaca. Despite the very high prevalence of Candidatus M. haemolamae, most infected alpacas did not show clinical abnormalities. The absence of maternal colostrum intake suggests that the cria was not infected by colostrum. Further investigations are needed to assess the transmission dynamics of Candidatus M. haemolamae in Italian alpaca herds.