Between October 1, 2002, and January 1, 2006, 15 llamas and 34 alpacas that were admitted to the Oregon State University Veterinary Teaching Hospital or submitted in whole or in part to the Oregon State University Veterinary Diagnostic Laboratory were found to have fecal oocysts or intestinal coccidial stages morphologically consistent with Eimeria macusaniensis. Of the 44 camelids for which age was recorded, 13 were between 3 weeks and 7 months old, 9 were between 1 and 3 years old, 5 were between 3 and 5 years old, and 17 were between 6 and 18 years old. Thirty-three were female, and 14 were male. These camelids represented 5.5% of all camelids admitted to the Veterinary Teaching Hospital, 8.6% of all camelid carcasses submitted to the Veterinary Diagnostic Laboratory for necropsy, and 0.4% of all camelid tissue samples submitted for histologic evaluation during this 39-month period. Sex and age distributions for these 49 camelids were not significantly (χ2 test; P = 0.108 and 0.254, respectively) different from distributions for the general hospital population during this period. Infected camelids came from 29 herds.
Ten llamas and 9 alpacas were submitted in whole or in part to the Veterinary Diagnostic Laboratory for postmortem examination. Of these, 7 were reported to have been found dead. The most common owner complaints for the remaining 12 were weight loss (n = 5), increased recumbency (5), decreased appetite (5), diarrhea (4), a recent history of transport (3), and lethargy (3). Other complaints included suspected transient choke (n = 1) and drooling of clear saliva (1). Three of the 4 camelids with diarrhea were the youngest of these 19 camelids; all 3 were < 1 year old.
Five llamas and 25 alpacas were admitted to the Veterinary Teaching Hospital. Common owner complaints and physical examination findings were lethargy (n = 15), weight loss (14), diarrhea (14), decreased appetite (13), a recent history of transport (11), increased recumbency (8), seizures or other neurologic signs (5), colic (4), and dyspnea (4). Also identified were abdominal distention (n = 3), salivary loss (2), dysphagia (1), a putrid oral odor (1), a heart murmur (1), and a stiff gait (1). Lethargy, decreased appetite, or weakness were the major complaints in 20 of the 30 camelids admitted to the Veterinary Teaching Hospital, diarrhea was the major complaint in 6, and colic was the major complaint in 1. The remaining 3 camelids were examined because of a fracture, dysphagia, and E macusaniensis infection identified by the referring veterinarian. Five of the 14 camelids with diarrhea were < 18 months old, and 7 of the 14 came from a single herd. Reported duration of clinical signs ranged from < 1 day to 1 month, but generally, camelids were reported to have been doing well until 1 to 3 days prior to admission. Once signs were noticed, rapid progression was common, except that diarrhea often resolved despite worsening of other signs. In 4 camelids, clinical signs were generally mild from the start and never worsened.
Heart rate was > 72 beats/min on initial examination in 14 of the 30 camelids admitted to the Veterinary Teaching Hospital, 10 of which subsequently died. Rectal temperature was < 37.5°C (99.5°F) in 14 camelids, 11 of which subsequently died, and > 39.2°C (102.5°F) in 1. Respiratory rate was > 30 breaths/min in 6 camelids, 5 of which subsequently died. Fifteen of the 30 camelids admitted to the Veterinary Teaching Hospital survived to discharge.
Blood analyses were performed at the time of admission in 29 of the 30 hospitalized camelids (Tables 1 and 2). The most common biochemical abnormalities were high nonesterified fatty acid concentrations (13/16), hypoalbuminemia (20/25), hypoproteinemia (21/29), high aspartate aminotransferase activity (16/23), hypokalemia (17/27), hyperglycemia (17/28), hyperketonemia (9/16), hyponatremia (14/28), and hyperlactemia (10/21). Common hematologic abnormalities were leukocytosis (7/22), neutrophilia (7/18), high band neutrophil count (14/19), monocytosis (6/19), and eosinopenia (15/19). The RBC count was within reference limits in 15 of 18 camelids, but 5 of 18 camelids had low hemoglobin concentration, and 9 of 29 had low PCV.
Results of biochemical analyses performed in llamas and infected with Eimeria macusaniensis.
|Variable||No. of camelids (No. that did not survive)|
|No. with value < lower reference limit||No. with value within reference limit||No. with value > upper reference limit|
|pH||5 (5)||14 (8)||2 (1)|
|Total CO2||11 (7)||7 (3)||9 (4)|
|Sodium||14 (7)||14 (7)||0 (0)|
|Potassium||17 (7)||10 (6)||0 (0)|
|Chloride||11 (7)||15 (6)||1 (1)|
|Ionized calcium||10 (7)||10 (7)||0 (0)|
|Total calcium||9 (2)||9 (6)||2 (1)|
|Anion gap||10 (2)||11 (5)||7 (7)|
|Glucose||5 (5)||6 (2)||17 (7)|
|Lactate||0 (0)||11 (5)||10 (8)|
|Urea nitrogen||4 (1)||13 (6)||8 (6)|
|Creatinine||2 (1)||13 (3)||10 (9)|
|Plasma protein||21 (11)||6 (2)||2 (2)|
|Serum protein||15 (6)||4 (2)||0 (0)|
|Albumin||20 (10)||5 (3)||0 (0)|
|Cholesterol||6 (3)||6 (2)||4 (3)|
|Triglyceride||0 (0)||12 (5)||4 (3)|
|BOHB||0 (0)||7 (4)||9 (3)|
|NEFA||0 (0)||3 (3)||13 (4)|
|Creatine kinase||0 (0)||19 (8)||4 (3)|
|GGT||1 (0)||12 (5)||11 (7)|
|AST||1 (0)||6 (1)||16 (10)|
|SDH||0 (0)||14 (5)||3 (2)|
|Phosphorus||4 (1)||10 (3)||4 (4)|
|Magnesium||1 (0)||14 (6)||2 (2)|
BOHB = β-Hydroxybutyrate. NEFA = Nonesterified fatty acids. GGT = γ-Glutamyl transferase. AST = Aspartate aminotransferase. SDH = Sorbitol dehydrogenase.
Results of hematologic analyses performed in llamas and alpacas infected with E macusaniensis.
|Variable||No. of camelids (No. that did not survive)|
|No. with value < lower reference limit||No. with value within reference limit||No. with value > upper reference limit|
|WBC count||1 (1)||14 (8)||7 (4)|
|Neutrophil count||3 (1)||8 (4)||7 (4)|
|Band neutrophil count||0 (0)||5 (2)||14 (7)|
|Lymphocyte count||0 (0)||16 (7)||3 (2)|
|Monocyte count||0 (0)||13 (6)||6 (3)|
|Eosinophil count||15 (8)||4 (1)||0 (0)|
|RBC count||0 (0)||15 (5)||3 (3)|
|Hemoglobin||5 (2)||13 (6)||0 (0)|
|PCV||9 (4)||20 (11)||0 (0)|
|MCH||9 (4)||9 (4)||0 (0)|
|Fibrinogen||0 (0)||20 (10)||1 (0)|
MCH = Mean corpuscular hemoglobin.
The Mann-Whitney rank sum test was used to compare physical examination, hematologic, and biochemical findings between camelids that survived and those that died or were euthanized (Table 3). Surviving camelids were found to have significantly lower heart rates; anion gap; PCV; serum hemoglobin, urea nitrogen, creatinine, and total bilirubin concentrations; and serum creatine kinase and G-glutamyl transferase activities and significantly higher rectal temperatures than nonsurviving camelids. Other physical examination, hematologic, and biochemical findings were not significantly different between surviving and nonsurviving camelids.
Comparison of selected physical, biochemical, and hematologic findings in llamas and alpacas with E macusaniensis infection that did or did not survive.
|Variable||Survivors||Nonsurvivors||P value*||Reference range|
|Heart rate (beats/min)||66 (60–80) n = 13||96 (71–119) n = 15||0.009||48–80|
|Rectal temperature (°C)||38.3 (37.6–38.90) n = 14||37.1 (34.6–37.8) n = 15||0.002||NA|
|Anion gap (mEq/L)||12.7 (11.3–15.2) n = 14||22.0 (12.3–28.7) n = 14||0.014||15–27|
|BUN (mg/dL)||18.0 (12.8–23.0) n = 13||27.6 (20.4–48.0) n = 13||0.021||13–28|
|Creatinine (mg/dL)||1.2 (1.0–1.4) n = 13||2.3 (1.3–3.8) n = 13||0.013||0.9–1.7|
|Bilirubin (mg/dL)||0.10 (0.10–0.20) n = 13||0.25 (0.15–0.40) n = 8||0.027||< 0.4|
|Creatine kinase (U/L)||128 (75–205) n = 13||265 (206–1,468) n = 10||0.014||43–750|
|GGT (U/L)||15 (11–43) n = 13||52 (15–78) n = 12||0.050||10–37|
|PCV (%)||28 (24–30) n = 14||32 (27–35) n = 15||0.022||27–45|
|Hemoglobin (g/dL)||12.6 (10.9–14.0) n = 11||15.9 (12.5–16.1) n = 7||0.046||11.9–19.4|
Data are given as median (interquartile [25th to 75th percentile] range).
Mann-Whitney rank sum test.
NA = Not applicable. To convert degrees Celsius to Fahrenheit, multiply by 9/5 and add 32.
See Table 1 for remainder of key.
Feces (n = 7), blood (5), liver biopsy specimens (3), and peritoneal fluid (2) collected prior to death from select camelids were submitted for bacterial culture. General bacterial culture techniques were used for all samples, except that culture techniques specific for identification of salmonellae and clostridia were used on fecal samples. Bacterial culture of one of the blood samples yielded Escherichia coli, and culture of another blood sample yielded Corynebacterium spp. Bacterial culture of one of the liver biopsy specimens yielded Acinetobacter spp, and culture of one of the fecal samples yielded a heavy growth of Clostridium perfringens.
Postmortem specimens submitted for bacterial culture included intestinal tissue or contents (n = 12), mesenteric lymph nodes (10), liver (8), lung (4), feces (2), and peritoneal fluid (1). General bacterial culture techniques were used for liver, lung, and peritoneal fluid specimens, whereas culture techniques specific for identification of salmonellae and clostridia were used on intestinal, mesenteric lymph node, and fecal specimens. Liver specimens from 2 llamas yielded E coli, a liver specimen from 1 camelid and a lung specimen from another camelid yielded β-hemolytic Streptococcus spp, a lung specimen yielded a mixed population of gram-negative bacteria, an intestinal specimen yielded Clostridium spp, and a mesenteric lymph node specimen yielded group B Salmonella spp.
Feces or intestinal contents were collected within 24 hours of admission or necropsy from 42 of the camelids. No E macusaniensis oocysts were seen in samples from 17 camelids, 1 to 100 oocysts/g were seen in samples from 11 camelids, 101 to 250 oocysts/g were seen in samples from 7 camelids, 251 to 500 oocysts/g were seen in samples from 3 camelids, and > 500 oocysts/g were seen in samples from 4 camelids. The examination technique involved mixing 4 g of solid feces or intestinal contents or 4 mL of liquid feces or intestinal contents with 26 mL of a saturated saline solution (specific gravity, 1.202), straining the mixture through gauze, and loading the strained mixture onto a McMaster counting chamber. Because previous experiences with this parasite had revealed poor flotation in saturated saline solutions, the sample was allowed to sit in the chamber for 15 minutes before counting and the microscope was focused on both the surface and floor of the counting chamber. Additionally, direct smears of feces were examined, and oocysts were seen in samples from 1 additional alpaca for which results of the modified McMaster test had been negative. Examination of follow-up fecal samples collected from 2 alpacas that initially had negative McMaster test results revealed oocysts, with oocyst count peaking at 7,500 oocyst/g 1 week after admission in 1 of the 2 alpacas. For the other alpaca, results were not positive until the fourth sample, which was collected 10 days after admission, was examined. In all cases, the size and shape of the oocysts were considered diagnostic for E macusaniensis1 (Figure 1).
Other potential pathogens isolated from the feces of infected camelids included small coccidia (Eimeria lamae, Eimeria alpacae, or Eimeria punoensis; all < 45 μm in maximum length; n = 17); strongyle ova (13); coronavirus (3); Cryptosporidium spp, Trichuris spp, Capillaria spp, and Giardia spp (2 each); and Nematodirus spp (1). In only 10 of the 42 samples were > 400 nematode ova or small coccidia oocysts found, and in 15 of the 42 samples, no potential pathogens beside E macusaniensis were found.
In camelids in which results of fecal examinations for E macusaniensis were negative, infection was confirmed by means of histologic examination of intestinal tissue. In all but 1 case, intestinal specimens were collected postmortem. In 1 alpaca, jejunal biopsy specimens were obtained during abdominal exploratory surgery performed because of signs of colic, and organisms were identified during cytologic examination of impression smears (Figure 2) as well as during histologic examination of frozen tissue sections. Results of modified McMaster tests performed on fecal samples from this alpaca subsequently became positive.
In total, intestinal specimens from 34 camelids were examined. Multiple sections of small intestine were available from all but 5 of the 34. Eimeria macusaniensis was identified on the basis of its characteristic size and appearance, including meronts > 100 μm long; macrogamonts with prominent wall-forming bodies; and maturing oocysts with the characteristic size, shape, and appearance.2 Larger parasitophorus vacuoles; the absence of maturing macrogamonts; and grossly disproportionate numbers of meronts, compared with macrogamonts, aided in the differentiation of meronts from microgamonts in some camelids. When few to moderate numbers of parasites were identified, they were localized near the base of the villi, but in heavily parasitized camelids, the entire villus was affected. Occasional forms appeared to be in the lamina propria. Lesions were most severe in specimens from the ileum and distal portion of the jejunum. Lesions were rarely seen in colonic specimens. When multiple sections of jejunum were available, it was common for some to contain no or few parasites and others to have complete obliteration of the mucosa. Rarely, gross thickening or serosal cobblestoning of the intestine or punctate, white, plaque like mucosal lesions were seen. Examination of impression smears of intestinal mucosa from 1 alpaca revealed high numbers of organisms (several hundred per slide) in the region of plaques and far fewer (3 to 4/slide) in grossly normal adjacent regions of the jejunum and ileum. In some camelids, multiple stages, including mature oocysts, were found, suggesting ongoing exposure for at least 30 days (Figure 3).
Examination of tissue specimens from 10 camelids for which results of fecal examinations were positive revealed early gametocytes in 6, gametocytes with distinct wall-forming bodies in 5, mature gametocytes in 4, and oocysts in 4. Examination of tissue sections from 13 camelids for which results of fecal examination were negative for E macusaniensis revealed early gametocytes in 9, gametocytes with distinct wall-forming bodies in 6, mature gametocytes in none, and oocysts in 1 (Figure 4). In 3 of these 13 camelids, only a uniform, mucosa-obliterating population of meronts or early macrogamonts was seen, suggesting recent exposure.
Other lesions identified or confirmed during postmortem examination included hepatic lipidosis (n = 10), pulmonary edema (4), evidence of sepsis (4), gastric ulceration (2), forestomach acidosis (1), colonic feed impaction (1), biliary carcinoma (1), perforation of the colon (1), polioencephalomalacia (1), and glossitis (1). The camelid with polioencephalomalacia had not been treated prior to admission and died within 90 minutes of admission. Severe parasitism by small coccidia was identified in only 2 camelids. Altogether, lesions caused by E macusaniensis appeared to be the primary or most important lesion in at least 11 of the 19 camelids submitted to the Veterinary Diagnostic Laboratory and in 25 of the 30 camelids admitted to the Veterinary Teaching Hospital.
Fifteen camelids were involved in outbreaks of eimeriosis on 4 farms. These farms reported 5 to 20 deaths over periods ranging from 1 week to 3 months, usually in association with a variety of postmortem diagnoses, including hepatic lipidosis, gastric ulceration, and other forms of endoparasitism. For all but 1 farm, multiple cases of E macusaniensis infection were confirmed. In the most severe outbreak, a group of 30 alpacas was transported in late summer to a new farm and placed on a pasture that had been vacant for 6 months. The first death occurred 20 days after the move, and severe prepatent E macusaniensis meront infection was confirmed histologically. Despite treatment of the entire herd with amprolium hydrochloride, an additional 6 alpacas became ill within 13 days, 4 of which died or were euthanized. Two of the 4 that died were determined by means of histologic examination to have had prepatent infections. The two survivors eventually had positive fecal test results. Results of modified McMaster tests performed at Oregon State University on 6 fecal samples obtained from 3 alpacas in this herd within 33 days of the move were all negative for E macusaniensis. Five other alpacas developed lethargy, diarrhea, and inappetance and were found to have patent infections approximately 37 days after the move. Results of modified McMaster tests performed at Oregon State University on fecal samples obtained from 6 alpacas in this herd 37 or more days after the move were all positive, but oocyst count was never > 375/g. No other cause of illness was identified in the alpacas that sickened or died in this herd. Resident alpacas moved to the same pasture at the same time appeared healthy and were not tested at the Veterinary Teaching Hospital.
Treatment of affected camelids varied with the type and severity of clinical signs and laboratory abnormalities. The few with mild or no compatible clinical signs or laboratory abnormalities were mainly observed for evidence of worsening of their condition. Many camelids were transfused with 2 to 6 units (600 to 1,800 mL) of plasma in an attempt to maintain serum albumin concentration > 2 g/L and total plasma protein concentration > 4 g/L. One severely affected alpaca received 22 units (6.6 L) of llama plasma over an 18-day period. Other supportive treatments included IV administration of fluids to restore or maintain hydration; partial parenteral nutrition to decrease protein catabolism; antimicrobials to treat or prevent secondary bacterial infections; and flunixin meglumine for its antipyretic, anti-inflammatory, and antiendotoxic effects. Intravenous fluid administration was usually initiated after any initial plasma transfusions were given; fluid administration rate was no greater than 50 mL/kg/d (23 mL/lb/d) to avoid complications associated with overhydration in animals with hypoproteinemia. The constitution of the fluids varied with the abnormalities present each day for each case but generally consisted of a polyionic crystalloid solution with or without additives, such as potassium chloride or sodium bicarbonate, or consisted of a partial parenteral nutrition solution if fat mobilization or hepatic lipidosis was suspected.
Three camelids underwent surgical exploration because of persistent signs of colic and ultrasonographic findings of fluid-filled, atonic small intestine. No other cause for the clinical signs was identified. In only one of these patients was gross intestinal thickening (cobblestoning) identified. The llama with the gastric adenocarcinoma also underwent surgical exploration to investigate persistent weight loss and marked thickening of the wall of the third gastric compartment identified during ultrasonographic examination.
Specific treatment for E macusaniensis infection included oral administration of amprolium hydrochloride (10 mg/kg [4.5 mg/lb] in a 1.5% solution, PO, q 24 h for up to 15 days) or sulfadimethoxine (110 mg/kg [50 mg/lb], PO, q 24 h for up to 10 days). In a few cases, these agents were used in combination. Camelids treated with amprolium for > 5 days were also usually given thiamine hydrochloride (10 mg/kg, SC, q 24 h) after the fifth day. High dosages and extended periods of administration were used because of a perceived lack of efficacy in some of the first cases to be treated. In retrospect, these agents appear to have been most efficacious against earlier stages of the organism, and the increase in fecal oocyst counts and in the number of organisms found at necropsy in these first cases likely reflected maturation of later, more resistant stages of the organism. It is unknown whether treatment prior to admission of some camelids reduced overall shedding.
Seven of the 15 nonsurviving camelids died or were euthanized within 12 hours after admission to the Veterinary Teaching Hospital. The remainder, including 2 alpacas with hepatic lipidosis, 1 with colonic rupture, 1 with persistent azotemia, and the llama with carcinoma, survived between 2 and 8 days. For the 49 camelids as a group, mortality rate was 8/13 among individuals < 1 year old, 6/9 among individuals between 1 and 3 years old, 3/5 among individuals between 3 and 5 years old, and 12/17 among individuals ≥ 6 years old. We did not detect a significant association between age group and outcome (survived vs did not survive; χ2 test; P = 0.949).
The 15 surviving camelids generally were reported to progress well for at least 3 months after discharge. None was readmitted or reported to have further signs consistent with eimeriosis. Although infected camelids often lost weight prior to and during the hospitalization period, body weight often remained stable for up to 2 weeks after discharge before weight gain was noticed.
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