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Misdiagnosed infected aneurysm presenting as pyrexia of unknown origin (PUO)

Abdikarim M, Shahari S, Idris MA, Hanafiah H, Kosai NR, Das S

Clin Ter, 2014;165(4):199-201.
PMID: 25203333 DOI: 10.7417/CT.2014.1733

Infected aneurysm is a life threatening clinical condition that is associated with significant morbidity and mortality. Early detection is essential for a rapid and efficacious initial treatment for better prognosis. Since the introduction of antibiotic therapy and concomitant decline of endocarditis, true mycotic aneurysms are rarely seen. The usual treatment consists of antibiotics along with aggressive surgical debridement of the infected tissue and vascular reconstruction, if needed. We here describe an infected aneurysm presenting as pyrexia of unknown origin and discuss the clinical features and challenges encountered in the treatment.
Molecular evidence of Sarcocystis nesbitti in water samples of Tioman Island, Malaysia

Shahari S, Tengku-Idris TI, Fong MY, Lau YL

Parasit Vectors, 2016 11 23;9(1):598.
PMID: 27881179

BACKGROUND: Sarcocystis are intracellular protozoan parasites that are characterised by their ability to invade muscle tissue and form intramuscular sarcocysts. A muscular sarcocystosis outbreak was reported by travellers returning from Tioman Island in 2011 and 2012 where Sarcocystis nesbitti was identified as the main cause. The source of the S. nesbitti that was involved has remained elusive, although water is hypothesised to be the main cause of transmission. A surveillance study was therefore undertaken in the northern regions of Tioman Island to identify the source of S. nesbitti by screening rivers, water tanks, wells and seawater.
METHODS: Water samples were collected from rivers, water tanks, wells and seawater on Tioman Island over the course of April to October 2015. Water samples were indirectly screened for Sarcocystis species by obtaining sediment from respective water sources. PCR amplification of the 18S rRNA gene region was conducted to identify positive samples. Microscopy was used in an attempt to reappraise PCR results, but no sporocysts were detected in any of the samples.
RESULTS: A total of 157 water samples were obtained and 19 were positive for various Sarcocystis species. Through BLASTn and phylogenetic analysis, these species were found to be S. singaporensis, S. nesbitti, Sarcocystis sp. YLL-2013 and one unidentified Sarcocystis species.
CONCLUSIONS: This is the first positive finding of S. nesbitti in water samples on Tioman Island, which was found in a water tank and in river water samples. This finding supports the hypothesis that water was a potential medium for the transmission of S. nesbitti during the outbreak. This will potentially identify areas in which preventive measures can be taken to prevent future outbreaks.
Molecular Evidence of Sarcocystis Species Infecting Reptiles in Peninsular Malaysia

Mohd Fadil NF, Tengku-Idris TIN, Shahari S, Fong MY, Lau YL

Iran J Parasitol, 2020 2 27;14(4):623-630.
PMID: 32099565

Background: The genus Sarcocystis consists of intracellular coccidian protozoan parasites with the ability to invade muscle tissue and mature into sarcocysts, causing the zoonotic disease sarcocystosis. These parasites have an obligatory two-host life cycle, which correlates with prey-predator relationship. The distribution and prevalence of Sarcocystis in reptiles remains unclear, despite several previous reports. The aim of this study was to identify the genetic assemblage of the species of Sarcocystis infecting Malaysian snakes and lizards by screening stool samples.
Methods: Overall, 54 fecal samples of various snake species and four fecal samples of several lizard species in Malaysia were taken within the course of August 2015 to January 2016 from Seremban, Melaka, Tioman Island, Pahang, Klang and Langkawi Wildlife Park located in Malaysia. The samples were examined for Sarcocystis through PCR amplification of the 18S rDNA sequence at the Department of Parasitology, University of Malaya.
Results: Fourteen snake fecal samples were positive via PCR; however, only eight samples (14%) were found positive for Sarcocystis species, whereas four were positive for other genera and the identity of another three samples was unable to be determined. Further phylogenetic analysis of the 18S rDNA sequences revealed that the snakes were infected with either S. singaporensis, S. lacertae, or undefined Sarcocystis species closely related to either S. singaporensis or S. zuoi. Sarcocystis nesbitti infection was not identified in any of the infected snakes.
Conclusion: This is the first report of identification of S. lacertae in the black-headed cat snake.
Short communication: Genetic variants of Sarcocystis cruzi in infected Malaysian cattle based on 18S rDNA

Ng YH, Fong MY, Subramaniam V, Shahari S, Lau YL

Res Vet Sci, 2015 Dec;103:201-4.
PMID: 26679818 DOI: 10.1016/j.rvsc.2015.10.009

Sarcocystis species are pathogenic parasites that infect a wide range of animals, including cattle. A high prevalence of cattle sarcocystosis has been reported worldwide, but its status is unknown in Malaysia. This study focused on utilizing 18S rDNA to identify Sarcocystis species in Malaysian cattle and to determine their genetic variants. In this study, only Sarcocystis cruzi was detected in Malaysian cattle. The intra-species S. cruzi phylogenetic tree analysis and principal coordinate analysis (PCoA), respectively displayed two minor groups among the parasite isolates. This finding was supported by high Wright FST value (FST=0.647). The definitive hosts (dogs) may play a fundamental role in the development of S. cruzi genetic variants. Additionally, the existence of microheterogeneity within the S. cruzi merozoites and/or distinct genetic variants arisen from independent merozoites in mature sarcocysts, possibly contributed to the existence of intra-species variations within the population.
Fulltext Cytoadherence Properties of Plasmodium knowlesi-Infected Erythrocytes

Lee WC, Shahari S, Nguee SYT, Lau YL, Rénia L

Front Microbiol, 2021;12:804417.
PMID: 35069511 DOI: 10.3389/fmicb.2021.804417

Plasmodium knowlesi is responsible for zoonotic malaria infections that are potentially fatal. While the severe pathology of falciparum malaria is associated with cytoadherence phenomena by Plasmodium falciparum-infected erythrocytes (IRBC), information regarding cytoadherence properties of P. knowlesi-IRBC remained scarce. Here, we characterized the cytoadherence properties of RBC infected with the laboratory-adapted P. knowlesi A1-H.1 strain. We found that late-stage IRBC formed rosettes in a human serum-dependent manner, and rosettes hampered IRBC phagocytosis. IRBC did not adhere much to unexposed (unstimulated) human endothelial cell lines derived from the brain (hCMEC/D3), lungs (HPMEC), and kidneys (HRGEC). However, after being "primed" with P. knowlesi culture supernatant, the IRBC-endothelial cytoadherence rate increased in HPMEC and HRGEC, but not in hCMEC/D3 cells. Both endothelial cytoadherence and rosetting phenomena were abrogated by treatment of P. knowlesi-IRBC with trypsin. We also found that different receptors were involved in IRBC cytoadherence to different types of endothelial cells. Although some of the host receptors were shared by both P. falciparum- and P. knowlesi-IRBC, the availability of glycoconjugates on the receptors might influence the capacity of P. knowlesi-IRBC to cytoadhere to these receptors.
Correction: Plasmodium knowlesi: the game changer for malaria eradication

Lee WC, Cheong FW, Amir A, Lai MY, Tan JH, Phang WK, et al.

Malar J, 2023 Oct 19;22(1):316.
PMID: 37858164 DOI: 10.1186/s12936-023-04732-x
Genetic polymorphism and clustering of the Plasmodium cynomolgi Duffy binding protein 1 region II of recent macaque isolates from Peninsular Malaysia

Latif ENM, Noordin NR, Shahari S, Amir A, Lau YL, Cheong FW, et al.

Parasitol Res, 2024 Jan 19;123(1):105.
PMID: 38240877 DOI: 10.1007/s00436-024-08125-0

Plasmodium cynomolgi is a simian malaria parasite that has been increasingly infecting humans. It is naturally present in the long-tailed and pig-tailed macaques in Southeast Asia. The P. cynomolgi Duffy binding protein 1 region II [PcDBP1(II)] plays an essential role in the invasion of the parasite into host erythrocytes. This study investigated the genetic polymorphism, natural selection and haplotype clustering of PcDBP1(II) from wild macaque isolates in Peninsular Malaysia. The genomic DNA of 50 P. cynomolgi isolates was extracted from the macaque blood samples. Their PcDBP1(II) gene was amplified using a semi-nested PCR, cloned into a plasmid vector and subsequently sequenced. The polymorphism, natural selection and haplotypes of PcDBP1(II) were analysed using MEGA X and DnaSP ver.6.12.03 programmes. The analyses revealed high genetic polymorphism of PcDBP1(II) (π = 0.026 ± 0.004; Hd = 0.996 ± 0.001), and it was under purifying (negative) selection. A total of 106 haplotypes of PcDBP1(II) were identified. Phylogenetic and haplotype analyses revealed two groups of PcDBP1(II). Amino acid length polymorphism was observed between the groups, which may lead to possible phenotypic difference between them.
Fulltext The prevalence of simian malaria in wild long-tailed macaques throughout Peninsular Malaysia

Shahari S, Bin Abdullah ML, Binti Isman Rohimly AA, Binti Ashrat N, Amir A, Atroosh WMM, et al.

Sci Rep, 2024 Mar 12;14(1):6023.
PMID: 38472278 DOI: 10.1038/s41598-024-54981-2

The parasite Plasmodium knowlesi has been the sole cause of malaria in Malaysia from 2018 to 2022. The persistence of this zoonotic species has hampered Malaysia's progress towards achieving the malaria-free status awarded by the World Health Organisation (WHO). Due to the zoonotic nature of P. knowlesi infections, it is important to study the prevalence of the parasite in the macaque host, the long-tailed macaque (Macaca fascicularis). Apart from P. knowlesi, the long-tailed macaque is also able to harbour Plasmodium cynomolgi, Plasmodium inui, Plasmodium caotneyi and Plasmodium fieldi. Here we report the prevalence of the 5 simian malaria parasites in the wild long-tailed macaque population in 12 out of the 13 states in Peninsular Malaysia using a nested PCR approach targeting the 18s ribosomal RNA (18s rRNA) gene. It was found that all five Plasmodium species were widely distributed throughout Peninsular Malaysia except for states with major cities such as Kuala Lumpur and Putrajaya. Of note, Pahang reported a malaria prevalence of 100% in the long-tailed macaque population, identifying it as a potential hotspot for zoonotic transmission. Overall, this study shows the distribution of the 5 simian malaria parasite species throughout Peninsular Malaysia, the data of which could be used to guide future malaria control interventions to target zoonotic malaria.
Natural Plasmodium infection in wild macaques of three states in peninsular Malaysia

Amir A, Shahari S, Liew JWK, de Silva JR, Khan MB, Lai MY, et al.

Acta Trop, 2020 Nov;211:105596.
PMID: 32589995 DOI: 10.1016/j.actatropica.2020.105596

Zoonotic cases of Plasmodium knowlesi account for most malaria cases in Malaysia, and humans infected with P. cynomolgi, another parasite of macaques have recently been reported in Sarawak. To date the epidemiology of malaria in its natural Macaca reservoir hosts remains little investigated. In this study we surveyed the prevalence of simian malaria in wild macaques of three states in Peninsular Malaysia, namely Pahang, Perak and Johor using blood samples from 103 wild macaques (collected by the Department of Wildlife and National Parks Peninsular Malaysia) subjected to microscopic examination and nested PCR targeting the Plasmodium small subunit ribosomal RNA gene. As expected, PCR analysis yielded significantly higher prevalence (64/103) as compared to microscopic examination (27/103). No relationship between the age and/or sex of the macaques with the parasitaemia and the Plasmodium species infecting the macaques could be identified. Wild macaques in Pahang had the highest prevalence of Plasmodium parasites (89.7%), followed by those of Perak (69.2%) and Johor (28.9%). Plasmodium inui and P. cynomolgi were the two most prevalent species infecting the macaques from all three states. Half of the macaques (33/64) harboured two or more Plasmodium species. These data provide a baseline survey, which should be extended by further longitudinal investigations that should be associated with studies on the bionomics of the anopheline vectors. This information will allow an accurate evaluation of the risk of zoonotic transmission to humans, and to elaborate effective strategies to control simian malaria.