Camelidae and Cervidae Mycoplasma haemolamae – NAVLE Study Guide

Overview and Clinical Importance

Candidatus Mycoplasma haemolamae (CMh), formerly known as Eperythrozoon species or "EPE," is a hemotropic mycoplasma (hemoplasma) that infects erythrocytes of South American camelids (llamas, alpacas, guanacos, and vicunas). This wall-less, Gram-negative bacterium attaches to red blood cell membranes and can cause infectious anemia ranging from subclinical to life-threatening. Understanding this pathogen is critical for NAVLE/BCSE success as it represents a unique hemoparasite with specific diagnostic and treatment considerations in camelid medicine.

In cervids (deer species), related hemoplasmas including Mycoplasma ovis-like organisms and novel species such as Candidatus Mycoplasma haemocervae and Candidatus Mycoplasma erythrocervae have been identified, causing similar clinical presentations of anemia and lethargy, particularly in captive or farm-raised deer populations.

Etiology and Taxonomy

Classification

Candidatus Mycoplasma haemolamae belongs to the class Mollicutes, order Mycoplasmatales, family Mycoplasmataceae. The "Candidatus" designation indicates that this organism has not been fully cultured in vitro, preventing official species designation. Based on 16S rRNA gene sequencing, CMh is phylogenetically most closely related to Mycoplasma wenyonii (cattle) and Mycoplasma suis (swine).

Hemoplasma Species by Host

Organism Morphology

Hemotropic mycoplasmas are small (0.3-0.8 micrometers), wall-less bacteria that are pleomorphic in appearance. CMh organisms may appear as coccoid, bacillary, ring-shaped, or linear structures on Wright-Giemsa stained blood smears. They attach to erythrocyte membranes via thin fibrils and become partially embedded. On blood smear examination, organisms appear as small, basophilic dots on the edges or faces of red blood cells. In severe infections, organisms may also be seen free in the plasma space between cells.

Epidemiology

Prevalence

CMh has a worldwide distribution and is prevalent in both South American native populations and camelids kept in North America, Europe, and other regions. Prevalence studies have documented the following rates:

Transmission Routes

Primary transmission occurs through transfer of infected blood between animals. Documented and suspected routes include:

• Iatrogenic transmission: contaminated needles, syringes, surgical instruments during vaccination, shearing, tattooing, or castration
• Arthropod vectors: likely ticks, fleas, mosquitoes, and lice (not definitively confirmed experimentally for CMh)
• Blood transfusions: from carrier animals
• Vertical transmission: in utero (transplacental) transmission has been documented; colostrum transmission appears unlikely

Pathogenesis

Mechanism of Disease

CMh organisms attach to erythrocyte membranes via thin fibrils and become partially embedded. This attachment leads to: (1) increased erythrocyte fragility and osmotic sensitivity, (2) immune-mediated targeting and destruction of infected cells (erythrophagocytosis primarily in the spleen), and (3) glucose utilization by organisms that can exceed gluconeogenesis, leading to hypoglycemia in severe cases.

Disease Progression

Incubation period: PCR-positive results occur 4-6 days post-infection experimentally. Blood smear detection occurs 2-6 days after PCR becomes positive.

Acute phase: Characterized by bacteremia, which may be cyclic. In severely affected animals, up to 90-100% of erythrocytes may be parasitized. Organisms may be visible on blood smears during this phase.

Chronic carrier state: Most infected camelids become asymptomatic carriers. Organisms persist despite antibiotic treatment and/or immune response. The carrier state can be lifelong.

Factors Triggering Clinical Disease

Clinical signs typically manifest when the immune system cannot adequately control infection. Risk factors include:

• Immunosuppression (concurrent illness, corticosteroid administration)
• Stress (transport, parturition, gestation, poor nutrition)
• Concurrent infections (especially Haemonchus contortus)
• Neonates and crias (immature immune system)
• Splenectomy (removes primary site of erythrophagocytosis and bacterial clearance)

Clinical Signs

Clinical Presentation Spectrum

Clinical manifestations range from completely subclinical (most common) to severe life-threatening anemia. Signs are generally non-specific and often attributed to comorbidities rather than CMh infection alone.

Important: Icterus is NOT typically observed in CMh infections, unlike hemoplasma infections in other species (cats, swine). This is an important distinguishing feature.

Hemoplasma Infections in Cervids

In deer species (cervids), hemoplasma infections have been documented in white-tailed deer, reindeer, sika deer, pudu, marsh deer, and other species. The most commonly identified organisms are Mycoplasma ovis-like species. Clinical presentations in cervids include:

• Wild populations: Generally subclinical; no documented pathology or negative impacts
• Captive/farm-raised deer: Lethargy and anemia of varying severity, particularly in young animals
• Reindeer: Documented cases with clinical disease associated with M. ovis-like organisms
• White-tailed deer: High occurrence of subclinical infections (up to 87% in some herds); deer may serve as wildlife reservoirs

Diagnosis

Diagnostic Approach

Diagnosis of CMh infection relies on a combination of clinical history, hematologic examination, blood smear evaluation, and molecular testing. PCR is the gold standard diagnostic test and is significantly more sensitive than blood smear examination.

Diagnostic Methods Comparison

Blood Smear Evaluation

Sample requirements: EDTA-anticoagulated whole blood. Make smears IMMEDIATELY after collection - organisms detach from erythrocytes and die in aged samples (greater than 24 hours), leading to false-negative results and misidentification as stain precipitate.

Blood Smear Findings

Organism appearance:

• Small basophilic dots (coccoid, ring-shaped, or rod-like) on erythrocyte edges or faces
• May be seen free in plasma space in heavy infections
• Multiple organisms per RBC in severe parasitemia (up to 20+ per cell)

Differential diagnosis on blood smear:

• Stain precipitate: Found between cells, not on them; use fresh stain
• Howell-Jolly bodies: Nuclear remnants; found only intracellularly; usually single, round
• Basophilic stippling: Ribosome aggregates; found only intracellularly; diffuse punctate pattern

Hematologic Findings

Normal Camelid Erythrocyte Parameters

Camelid erythrocytes are unique among mammals - they are elliptical (oval) rather than biconcave discs. This affects interpretation of automated analyzers.

Anemia classification:

• Mild: PCV 0.20-0.22 L/L
• Moderate: PCV 0.15-0.20 L/L
• Severe: PCV 0.10-0.15 L/L
• Life-threatening: PCV less than 0.10 L/L

Treatment

Antimicrobial Therapy

Oxytetracycline is the mainstay of treatment for hemoplasma infections. However, it is critical to understand that treatment does NOT consistently eliminate the carrier state. Treated animals may remain chronic carriers despite clinical improvement.

Supportive Care

For clinically affected animals with severe anemia:

• Blood transfusion: For PCV less than 0.10-0.12 L/L; crossmatch recommended but not always performed; camelid-to-camelid transfusion is acceptable
• IV fluid therapy: Correct dehydration; may use 5% dextrose if hypoglycemic
• Dextrose supplementation: For hypoglycemia, especially in neonates
• Glucocorticoids: May decrease erythrophagocytosis in cases of severe immune-mediated hemolysis (use with caution; can worsen immunosuppression)
• Treat concurrent conditions: Especially Haemonchus contortus - anthelmintic treatment is often more critical than CMh treatment

Memory Aid - CMh Treatment: "OXY-5-ETD" OXY = Oxytetracycline is first-line 5 = Minimum 5 treatments ETD = Every Third Day dosing for LA formulation

Differential Diagnosis of Anemia in Camelids

When presented with an anemic camelid, consider the following differential diagnoses. Haemonchus contortus (barber pole worm) is the most common and clinically significant cause of anemia in camelids - more so than CMh.

Prognosis and Prevention

Prognosis

Prognosis for CMh infection is generally good to excellent for most animals. The majority of infected camelids remain as asymptomatic carriers with no impact on health or productivity. Even clinically affected animals typically respond well to supportive care and oxytetracycline treatment. Deaths are associated with heavy bacteremia in severely stressed or immunocompromised animals, particularly neonates.

Prevention

• Use sterile needles and equipment: Never reuse needles between animals; clean and disinfect surgical instruments
• Screen blood donors: Use PCR to test potential donors before transfusion
• Vector control: Control ticks, lice, flies where possible
• Minimize stress: Proper nutrition, avoid overcrowding, minimize transport stress
• Quarantine new animals: Test incoming animals, especially from high-prevalence regions