Friday, May 28, 2010
eimeria macusaniensis- EMAC in Alpacas PT 2
(taken from the same Survellience notes, (MAF NZ 2006), as in previous post- i hope this is of some help.
Eimeria macusaniensis in
camelids – a brief review
Of the four or five coccidial parasites known to infect llamas and
alpacas, namely Eimeria lamae, E alpacae, E punonensis, E ivitaensis
and E macusaniensis(1)(2)(3), only the first three have previously been
recorded in New Zealand(4). However, in July 2005 oocysts of
E macusaniensis were detected in the faeces of a ten-year-old female
alpaca on a property in Otago, approximately eight weeks after its
importation from Australia. Because of the supposed pathogenicity
of this protozoan, a limited survey was undertaken to determine its
presence elsewhere in New Zealand(5). Its general biology is briefly
All mammalian coccidia are considered to be quite host specific.
Thus coccidia of camelids are not infective to other domestic or wild
ruminants and those of the latter hosts will not infect camelids(6)(7).
Because of their genetic relatedness, it is generally accepted that all
camelids share the same species of coccidia. Thus E macusaniensis
infections have been recorded in alpacas (Vicugna pacos), llamas
(Lama glama), guanacos (Lama guanicoe)(8)(9) and vicunas (Vicugna
vicugna)(10). It has also been observed that both the oocyst and
the endogenous stages of E macusaniensis are almost identical to
those of E cameli of the dromedary (Camelus dromedarius) and
the bactrian camel (Camelus bactrianus)(11). This has prompted
speculation that these two coccidians might eventually be revealed
to be the same species (Duszynski et al. The coccidia of the World.
Distribution and prevalence
Infections of E macusaniensis have been reported in camelids in
Australia(12), North America(8)(11)(13), South America(2)(14), the United
Kingdom(15) and Germany(16). While most of these reports have
involved llamas, in some instances they include alpacas and guanacos
as well. In the United States, infections of E macusaniensis were found
in two of 144 (1.4%) llamas from Colorado and Wyoming(11) and in
two of 189 (1.0%) adult llamas in Oregon(13). A prevalence of 12%
was also recorded in 301 llamas from the midwestern United States(8).
There have been fewer investigations of the frequency of occurrence
of E macusaniensis infection in the other hosts but prevalences
of about 7% were found in 115 alpacas and 27 guanacos in the
midwestern United States(8). In other surveys, oocysts of
E macusaniensis were found in the faeces of 24% of 160 alpacas in
Peru(15) and in nine of 12 guanacos examined in Patagonia(17).
Although infections with E macusaniensis may be found in
both adult and younger hosts, the latter group tends to be more
frequently involved. Thus the highest prevalence of infection (67-
71%) was found in llamas of two and three months of age on a farm
in Germany, with somewhat lower levels of infection (16% and 26%,
respectively) recorded in mature dams and yearling males(16). Others
have reported similar results with prevalences significantly greater in
animals less than one year of age than in older animals, both in the
midwestern United States(8) and in Peru(17).
So far, E macusaniensis has been recorded on only a limited number
of properties in New Zealand and these have largely involved
infections in alpacas recently imported from Australia(5). However,
infections with other coccidial species have been detected in
previous importations(4) and it is difficult to believe that
E macusaniensis would somehow be selectively excluded from
these. Indeed, a far more likely scenario is simply that its presence
remained undetected either because fewer oocysts were present and/
or because of the low sensitivity of the examination procedure used
to detect them (see below). If this is correct, then it is possible that
the parasite has been present here for a number of years.
Life cycle and development
The life cycle of E macusaniensis is that of a typical coccidian
with infection initiated by the ingestion of sporulated oocysts
and endogenous development taking place in the small intestine
of infected hosts. Here there is a period of asexual reproduction
(schizogony or merogony) within epithelial cells, followed by sexual
differentiation (gametogony) into male microgametes and female
macrogametes that give rise to unsporulated oocysts, which are
shed in the faeces. By a process of sporogony or sporulation, four
sporocysts each containing two sporozoites are formed within the
oocyst, which then typically serves as the only source of infection for
all potential hosts.
Asexual and sexual reproduction do not continue indefinitely within
the host and, in the absence of reinfection, coccidial infections are
self-limiting in duration. Reinfection may take place but usually the
host develops a degree of immunity following primary infection.
In experimentally infected llamas, the interval between the ingestion
of sporulated oocysts of E macusaniensis and the subsequent first
appearance of unsporulated oocysts in their faeces (the pre-patent
period) was found to be 32-36 days. Oocyst shedding continued for
39-43 days with a mean total output during this patent period of 3-10
million oocysts. Reinfection two or three weeks after the end of the
first patency resulted in a prolonged pre-patent period of 37-40 days, a
shortened patent period of 20-23 days and a reduced oocyst output(16).
The time taken for oocysts excreted in the faeces to undergo and
complete sporulation, and thus become infective for other hosts, is
largely temperature and oxygen dependent and for most coccidial
In 2005, oocysts of Eimeria macusaniensis were
detected in the faeces of an alpaca in Otago. This
article briefly reviews the organism, its distribution, life
cycle and pathogenicity, and methods for its detection,
management and control.
species occurs within the range of 10-30oC. In the case of
E macusaniensis, sporulation has been found to take 12-15 days at
23oC(13). Others(16) report that the maximum number of sporulated
oocysts (85%) was obtained after 15 days at 30oC and after 25 days at
Diagnosis and detection
The diagnosis of E macusaniensis infection is largely based on
the detection of oocysts in host faeces. These may be readily
differentiated from the oocysts of the other coccidial species that
may be found in the faeces of llamas and alpacas by their greater size
(three to four times larger), brown colour, and prominent micropyle.
Detailed descriptions of the oocysts of all these species are provided
elsewhere(1)(2) but, briefly, those of E macusaniensis are pyriform in
shape and measure 80-110 μm long by 60-80 μm wide. They also
have very thick oocyst walls approximately 8-12 μm thick(11).
Like other coccidia, E macusaniensis oocysts may be detected by
standard flotation techniques. However, because of their large
size, flotation solutions with specific gravities of ≤ 1.2 may fail to
detect E macusaniensis infections and those with specific gravities
of 1.28-1.3 are required(8). Such oocysts may also be detected by
a sedimentation technique. Indeed, the latter technique, which is
likely to provide a more sensitive faecal examination procedure(2)(8),
represents the method of choice.
It is also important to note for diagnostic purposes that oocysts of
E macusaniensis are unlikely to be present in the faeces of animals less
than one month of age since the prepatent period is greater than 30
days. An epidemiological study in Germany, for example, found that
oocyst shedding was first detected when animals were two months
old(16). In addition, because of the long pre-patent period, it is possible
that acutely infected animals could die before oocysts are present in
their faeces. Although infection may sometimes be accompanied by
enteritis and diarrhoea(7), commonly few clinical signs are apparent(8).
In such cases, diagnosis depends on the histopathological examination
of the small intestine and the demonstration of schizonts, gametocytes
and oocysts in epithelial cells(12)(14).
Most coccidial infections in llamas and alpacas are described as
asymptomatic and self-limiting(6)(7). However, young animals may
show signs of clinical coccidiosis when faced with heavy infections
and at times of stress, and two of the coccidial species most frequently
associated with such outbreaks are E lamae and E macusaniensis(10). In
addition, co-infections of E ivitaensis and E macusaniensis have also
recently been implicated in fatal cases of diarrhoea in young alpacas
in Peru(18). Despite this, information relating to the pathogenicity
of E macusaniensis remains somewhat contradictory and confusing.
Thus in the paper of Rosadio and Ameghino(14), Guerrero et al(19) and
Guerrero and Leguia(20) are cited as suggesting that E macusaniensis is
minimally pathogenic. However, in the same paper J Alva is reported,
in a personal communication, as has having identified ‘clinical cases
caused by this organism in association with natural outbreaks of
diarrhoea in southern Peru’.
Other authors(17)(21) cited in the papers of Rickard and Bishop(13)
and Foreyt and Lagerquist(22) also consider that E macusaniensis is
pathogenic for alpacas, a conclusion supported by the reports of
Rosadio and Ameghino(14) and Lenghaus et al(12). The latter authors
certainly believed their report confirmed that E macusaniensis was
highly pathogenic in alpacas and that coccidiosis resulting in severe
damage to intestinal epithelia predisposes to necrotising enteritis
and death. Somewhat similar views were expressed by Leguia(10)
who considered that coccidiosis was mainly a problem of alpacas
reared in confinement but that frequent outbreaks of subacute
or acute infections occurred in animals born late in the breeding
season in Peru. He stated that such outbreaks seemed to be mainly
caused by infections of E lamae associated with E macusaniensis.
Such co-infections he considered to be highly pathogenic since
the first species destroyed the intestinal epithelium while the
second damaged the crypt glands and inhibited regeneration of the
epithelium. This resulted in complete stripping of the intestinal
mucosa and its total loss of function, leaving the intestinal wall
exposed to secondary viral or bacterial invasion. He(10) believed,
therefore, that there was a strong correlation between coccidiosis and
bacillary enterotoxaemia, which resulted in up to 50% mortality in
newborn animals in that country.
While enteritis has also been associated with E macusaniensis
infections in a three-month-old guanaco and an adult alpaca,
these infections were considered incidental findings at necropsy(7).
Jarvinen(8) also points out that the contribution of other pathogens
was not considered in the Rosadio and Ameghino(14) case. The same
author(8) further stated that the pathogenicity of E macusaniensis
had not been evaluated in controlled studies using experimentally
induced infections. Certainly, no clinical signs were associated with
infections in llamas in Jarvinen’s survey(8). However, others(16) have
since carried out experimental infections in llamas. In this latter
study, five one-month-old llamas, reared parasite-free, were orally
infected with 20,000 E macusaniensis oocysts while another twomonth-
old animal received 100,000. Although, the primary purpose
was to study the parasite’s pre-patent and patent periods, one would
have expected that any associated health issues would also have been
reported. The fact they were not, suggests that none were observed.
In summary, it would appear that while E macusaniensis may have
the potential to cause death and disease in both young and adult
camelids, the frequency with which it is likely to do so may have
been somewhat overstated.
Management and control
There is no published information relating specifically to the
longevity and survival of E macusaniensis oocysts. However,
coccidial oocysts are generally considered hardy long-lived resting
stages capable of withstanding the action of many chemical andphysical agents and it is likely the thick walls of those of
E macusaniensis make them particularly resistant to such challenges.
Once oocysts of this species are present in the environment,
decontamination of affected properties is, therefore, likely to be
difficult. Possibly some measure of control could be achieved by
a combination of faecal removal and animal treatment but total
eradication of infection from affected farms would appear to be an
In addition to exposure to the organism, clinical coccidiosis in
camelids is generally linked to a combination of stress factors
including weaning, overcrowding, cold, travel and poor nutrition(7).
Good management is, therefore, likely to be the key to preventing
infection with E macusaniensis becoming too much of a problem
on individual properties. Obviously the treatment of infections may
play a part as well but since no anticoccidials are registered for use
in camelids in New Zealand, this may be somewhat problematic.
Nevertheless, toltrazuril (Baycox, Bayer New Zealand Ltd), which is
registered for use in poultry and piglets here, is likely to represent
the best candidate. Previous studies have shown that this drug,
usually administered at a dose rate of 20 mg/kg, is effective against
all intracellular life cycle stages of a variety of other coccidial species
in a number of mammalian hosts(23).
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Journal of Protozoology 14, 613-6, 1967.
(2) Guerrero CA, Hernandez J, Bazalar H, Alva J. Eimeria macusaniensis n.sp.
(Protozoa: Eimeriidae) of the alpaca Lama pacos. Journal of Protozoology 18,
(3) Leguia G, Casas E. Eimeria ivitaensis (Protozoa: Eimeridae) en alpacas (Lama
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(19) Guerrero CA, Hernandez J, Alva J. Coccidiosis en alpacas. Revista Facultad
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Investigaciones Tropicales y de Altura 4, 79-83, 1970.
(22) Foreyt WJ, Lagerquist J. Experimental infections of Eimeria alpacae and
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