Human and animal sarcocystosis in Malaysia: A review

SARCOCYSTOSIS IN A CAPTIVE FLOCK OF THICK-BILLED PARROTS (RHYNCHOPSITTA PACHYRHYNCHA) FROM 2005 TO 2016: MORBIDITY, MORTALITY, DIAGNOSTICS, AND MANAGEMENT STRATEGIES

Sarcocystosis was diagnosed in a captive flock of thick-billed parrots (Rhynchopsitta pachyrhyncha) at the Wildlife Conservation Society's Queens Zoo. Since the index case in 2005, 45% of mortalities in birds over 30 days of age were due to sarcocystosis. Sarcocystis falcatula was repeatedly identified as the causative agent. The disease predominantly affected younger adult parrots. Administration of antiparasitic medications prior to development of respiratory signs prolonged life in infected birds, but disease was fatal until utilization of a three-drug combination (pyrimethamine, trimethoprim-sulfamethoxazole, and ponazuril). This protocol may require in excess of 6 mo of therapy to achieve clinical resolution of active disease. Plasma creatine kinase activity was found to be the most useful test in diagnosing infection and monitoring response to therapy. Polymerase chain reaction (PCR) for apicomplexan organisms on antemortem whole blood, blood smears, or dried blood spots helped confirm suspected cases, but due to the poor sensitivity was sometimes misleading when assessing response to therapy or resolution of clinical disease. Preventive measures, focusing on exclusion and removal of Virginia opossums (Didelphis virginiana) from zoo grounds failed to curtail the occurrence of sarcocystosis in the flock. Other preventative steps, such as modification of feeding stations to exclude potential arthropod paratenic hosts and prophylaxis trials with diclazuril, appeared to successfully mitigate new infections. Given the diagnostic and therapeutic challenges, prevention of exposure to S. falcatula is essential to ex-situ conservation efforts for thick-billed parrots.

Infection survey and morphological characteristics of Sarcocystis spp. in naturally infected Tibetan sheep from Qinghai in northwestern China

Sarcocystosis is a parasitic disease caused by intracellular coccidian protozoans that belong to the genus Sarcocystis. These parasites can cause diseases of the nervous system, abortion and economically significant losses in host animals. Previous studies have reported that Sarcocystis is found in mammals, birds and reptiles, while molecular and morphological studies of infected Tibetan sheep have not been performed in the Qinghai region. The aim of this study was to determine the prevalence of Sarcocystis spp. in Tibetan sheep in Qinghai, northwestern China. The results showed that in 1155 samples, sarcocysts from unspecified species were found in 50% (577/1155) of the sheep tissues by microscopy detection. The positive rates of sarcocysts in the diaphragmatic, esophageal and cardiac muscles were 78.4% (175/223), 29.1% (207/711), and 88.2% (195/221), respectively. Ultrastructural features were exclusively observed in Sarcocystis gigantea in the esophageal tissues. The specific architecture was characterized as a space between the two layers of the original capsule wall, which was filled with fiber bundles and tissue fluid. Cauliflower-like protrusions of the original capsule wall were observed toward the outer surface of the capsule. Prominent protrusions contained fibers and matrix. In addition, the Sarcocystis 18S rRNA genes from 6 esophageal tissue samples were cloned, sequenced, and aligned to related sequences from GenBank. All 5 S. gigantea sequences examined in this study were grouped into the same cluster and belonged to the same genotype. The other 5 Sarcocystis tenella sequences were obtained from cardiac muscle and diaphragm muscle and belonged to the same clade. Overall, this study revealed a high infection rate of Sarcocystis in Tibetan sheep in the region. The results of this study may provide a reference for further research investigating the sarcocystosis epidemic in Qinghai, China.

Sarcosporidiosis: An Emerging Disease in Yaks (Bos grunniens) on the Qinghai Tibetan Plateau (QTP), China

BACKGROUND

Sarcocystosis is a worldwide distributed parasitic zoonosis. However, scarce knowledge is available about the infection of sarcocystosis in yaks.

RESULTS

Herein, we conducted this study to survey the seroprevalence of sarcocystosis in yaks on the Qinghai Tibetan plateau. A total of 2549 serum samples were obtained during 2011-2017, which were assayed using commercial ELISA kits. The results revealed that the overall seroprevalence of sarcosporidiosis in QTP yaks was 0.90% (95 CI 0.6-1.4). The seroprevalence ranged from 0.20% (95 CI 0-1.1) to 1.67% (95 CI 0.8-3.0) in yaks in different areas. The seroprevalence was 0.73% (95 CI 0.3-1.4) in male yaks and 0.06% (95 CI 0.6-1.8) in female yaks. In different ages, the seroprevalence ranged from 0 (95 CI 0-1.4) to 1.47% (95 CI 0.6-3.0). In different years, the seroprevalence ranged from 0 (95 CI 0-1.4) to 1.86% (95 CI 0.7-4.0). In the current study herein, region and age were revealed to be the obvious influencing risk factors by conditional stepwise logistic regression.

DISCUSSION

The current study herein first found the emerging infection of sarcosporidiosis in yaks from high plateaus, which contributes to outline the epidemiological scenario of sarcosporidiosis in yaks in China. Moreover, our findings highlight the urgent need of studies in yaks on the QTP at further and more comprehensive level.