Case report details systemic toxoplasmosis in an adult alpaca

CURRENT FULL VERSION: A newly reported necropsy case is putting a rare camelid diagnosis back on the radar: systemic toxoplasmosis in an adult alpaca. In the Journal of Veterinary Diagnostic Investigation, investigators describe an 11-year-old female alpaca with three days of sternal recumbency before death and conclude that this is, to their knowledge, the first fatal toxoplasmosis case reported in an adult alpaca. The diagnosis was supported by gross pathology, histopathology, liver qPCR positive for Toxoplasma gondii, and immunohistochemical confirmation of both tachyzoites and bradyzoites in inflamed and necrotic tissues. (acvp.org)

What makes the case notable is how unusual clinical toxoplasmosis appears to be in adult South American camelids. General veterinary references describe toxoplasmosis as commonly subclinical in immunocompetent adults, with generalized fatal disease more often seen in young or immunocompromised animals. The conference abstract tied to this report explicitly notes that no predisposing cause was identified in this alpaca. That stands out because the pathology was widespread, involving liver, adipose tissue, pleura, lungs, and the first gastric compartment. (msdvetmanual.com)

The lesion profile was severe and multisystemic. Grossly, the alpaca had hydrothorax, ascites, hepatomegaly, fibrinous pleuritis, cranioventral bronchopneumonia, and pulmonary atelectasis. Microscopically, the case included chronic histiocytic, lymphocytic, and necrotizing hepatitis with portal bridging fibrosis, thrombosis in thoracic and abdominal adipose tissue, fibrinosuppurative pleuritis, pyogranulomatous pneumonia, and ulcerative gastritis in C1. The authors also highlighted chronic hepatitis as an especially unusual feature, noting that a similar lesion pattern had been described in what they identified as the only other systemic toxoplasmosis report in a South American camelid. (acvp.org)

That earlier comparator is a 2014 Journal of Parasitology case report of acute fatal systemic toxoplasmosis in a llama. In that report, the affected llama was 13 months old, and lesions involved multiple visceral organs including the heart, thyroid gland, stomach, intestine, diaphragm, kidneys, adrenal glands, and liver. The publication described clinical toxoplasmosis as rare in camelids, reinforcing how limited the evidence base remains when practitioners are faced with a sick alpaca or llama showing nonspecific systemic decline. (pubmed.ncbi.nlm.nih.gov)

The broader epidemiology adds another layer. Serologic studies suggest exposure is not rare, even if overt disease is. A Swiss study of 571 South American camelids found measurable T. gondii seroprevalence and reviewed prior alpaca seroprevalence reports from Chile, the US, Germany, and the Czech Republic. Older work from Chile reported corrected alpaca seroprevalence of 16.3%, and a Peruvian study documented T. gondii infection in adult llamas and vicuñas. At the same time, reproductive disease data in camelids have been mixed: a 2007 Peruvian fetal study did not detect T. gondii DNA in aborted alpaca and llama fetuses, whereas a later report identified toxoplasmosis-associated abortion in an alpaca fetus. Together, those findings suggest exposure is established, but clinically recognized disease may be underdetected, underreported, or dependent on host and management factors that remain poorly defined. (pmc.ncbi.nlm.nih.gov)

There does not appear to be much published expert reaction yet specific to this new adult alpaca report, but the existing literature points in a consistent direction: camelids are exposed to T. gondii, while overt clinical toxoplasmosis remains uncommon enough that it may be overlooked. Standard references emphasize that felids are the definitive host and shed environmentally resistant oocysts, and that infection in intermediate hosts follows ingestion of contaminated feed, water, or other materials. For herd veterinarians and diagnosticians, that makes environmental management and exposure history relevant even when a case initially looks more like respiratory, hepatic, or septic disease than protozoal infection. (msdvetmanual.com)

One reason that matters in alpacas specifically is that species-focused baseline anatomy is still being filled in. A recent prospective cadaveric imaging study using CT, MRI, frozen cross-sections, and 3D reconstructions in seven alpacas found that all examined heads had dorsal and middle conchal, maxillary, frontal, and ethmoidal sinuses; most had a sphenoidal sinus; and bilateral lacrimal sinuses were present in five of seven specimens. Notably, the ventral conchal and palatine sinuses were absent in all specimens. The frontal sinus was consistently partitioned into a smaller medial compartment and a larger, variably concamerated lateral compartment in all but one head, and the ethmoidal air cells were organized into medial and lateral groups with different rostrocaudal extent and sinus connections. That work is not about toxoplasmosis directly, but it underscores a practical point: when alpacas present with respiratory signs, imaging abnormalities, or head-related disease, clinicians are often interpreting findings against a relatively sparse species-specific anatomic reference base. (onlinelibrary.wiley.com)

Why it matters: The practical takeaway for veterinary teams is diagnostic, not just academic. An adult alpaca with recumbency, hepatic lesions, pneumonia, pleuritis, or unexplained systemic inflammation would not typically put toxoplasmosis at the top of the list. But this case argues that it belongs on the differential list when pathology is multisystemic and especially when histologic protozoal forms are suspected. It also underscores the value of layered confirmation, including histopathology, PCR, and immunohistochemistry, because T. gondii can overlap morphologically with other apicomplexan organisms in routine sections. More broadly, as alpaca imaging and cross-sectional anatomy references improve, clinicians may be better positioned to separate primary sinonasal or upper-airway disease from systemic infectious processes presenting with respiratory involvement. (acvp.org; onlinelibrary.wiley.com)

What to watch: Next, watch for the full JVDI paper to add more detail on diagnostics, herd context, and any suspected exposure pathway, and for future case reports or retrospective studies to clarify whether adult camelid toxoplasmosis is truly rare, or simply rarely confirmed. It will also be worth watching whether expanding species-specific CT/MRI anatomy resources changes how often respiratory and sinus disease in alpacas is recognized early and distinguished from broader systemic illness. (acvp.org; onlinelibrary.wiley.com)