Displaying publications 1 - 20 of 108 in total

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  1. Simau FA, Ahmed U, Khan KM, Khan NA, Siddiqui R, Alharbi AM, et al.
    Parasitol Res, 2024 Jan 31;123(2):117.
    PMID: 38294565 DOI: 10.1007/s00436-024-08131-2
    The free living Acanthamoeba spp. are ubiquitous amoebae associated with potentially blinding disease known as Acanthamoeba keratitis (AK) and a fatal central nervous system infection granulomatous amoebic encephalitis (GAE). With the inherent ability of cellular differentiation, it can phenotypically transform to a dormant cyst form from an active trophozoite form. Acanthamoeba cysts are highly resistant to therapeutic agents as well as contact lens cleaning solutions. One way to tackle drug resistance against Acanthamoeba is by inhibiting the formation of cysts from trophozoites. The biochemical analysis showed that the major component of Acanthamoeba cyst wall is composed of carbohydrate moieties such as galactose and glucose. The disaccharide of galactose and glucose is lactose. In this study, we analyzed the potential of lactase enzyme to target carbohydrate moieties of cyst walls. Amoebicidal assessment showed that lactase was ineffective against trophozoite of A. castellanii but enhanced amoebicidal effects of chlorhexidine. The lactase enzyme did not show any toxicity against normal human keratinocyte cells (HaCaT) at the tested range. Hence, lactase can be used for further assessment for development of potential therapeutic agents in the management of Acanthamoeba infection as well as formulation of effective contact lens disinfectants.
  2. 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.
  3. Alimin AWF, Yusoff NAH, Kadriah IAK, Anshary H, Abdullah F, Jabir N, et al.
    Parasitol Res, 2023 Dec 14;123(1):49.
    PMID: 38095702 DOI: 10.1007/s00436-023-08067-z
    Parasitic dinoflagellates of the genus Hematodinium are known to infect various marine crustaceans worldwide, especially crabs and several species of shrimp and lobster. Some of these species are new host species and components of commercial fishery products. These parasitic species are predominantly found in the hemolymph of the host and cause pathological changes and functional damage to organs and tissues, leading to death. In recent years, these parasites have infected important commercially valuable species, particularly in European waters, US waters, Australian waters, and recently in Shandong Peninsula in China. These Hematodinium pathogens were also reported to affect wild shrimp in Chinese waters and in the English North Sea. These rapid spreads affect crustacean aquaculture industries, where they are indeed a significant threat to the sustainability of the aquaculture of important crustaceans. The fishery products industries are also under pressure from the invasion of this pathogen, as the crab meat produced has a bitter taste, which may reduce its marketability. In response to these threats, this review was aimed at providing a broader understanding of the development of parasite distribution and ecological aspects of Hematodinium. In addition, the interaction of these pathogens with their hosts, the environmental drivers of Hematodinium disease, and future research perspectives were discussed.
  4. Suphakhonchuwong N, Rungsihirunrat K, Kuesap J
    Parasitol Res, 2023 Dec;122(12):2871-2883.
    PMID: 37725258 DOI: 10.1007/s00436-023-07977-2
    Resistance to antimalarial drugs is a serious issue around the world. Widespread Plasmodium vivax and P. falciparum coinfections are commonly found in Thailand. Dihydroartemisinin and piperaquine (DHA-PPQ) have been used as first-line treatments for P. falciparum since 2015, and chloroquine (CQ) and primaquine (PQ) have remained first-line drugs for P. vivax for more than 60 years. Coinfections may lead parasites to evolve with regard to genetics under selective drug pressure. This study is aimed at investigating genes linked to antimalarial resistance in P. vivax before and after introduction of DHA-PPQ as a new drug regimen in Thailand. A total of 400 P. vivax isolates were collected from samples along the Thai-Myanmar and Thai-Malaysian borders before (2009-2015) and after (2016-2019) introduction of DHA-PPQ. Genomic DNA of P. vivax was obtained and subjected to analysis of five drug resistance-associated genes (Pvdhfr, Pvdhps, Pvmdr1, Pvcrt-o, and PvK12) by nested polymerase chain reaction (PCR), restriction fragment length polymorphism (RFLP), and nucleotide sequencing. A high prevalence of Pvdhfr was found in both endemic areas over the period. The quadruple (57I/58R/61M/117T) Pvdhfr haplotype was predominant in both periods in both endemic areas. Although the wild-type haplotype of Pvdhps was predominant in Thai-Malaysian isolates in both periods, a single mutant haplotype (383G) was dominant in Thai-Myanmar isolates during both periods. A low prevalence of the Pvmdr1 976F mutation was found in both periods among Thai-Myanmar isolates. A significant decrease in Pvmdr1 976F was identified in Thai-Malaysian isolates from the second period (p < 0.01). Only one nonsynonymous mutation of Pvcrt-o (193E) and one synonymous mutation of PvK12 (R584) were detected in four isolates (4.7%) and one isolate (0.5%) in the first period among Thai-Myanmar isolates, respectively. Thus, with limited clinical efficacy data, the low prevalence of drug-resistance markers may suggest that there is a low prevalence of P. vivax-resistant strains and that the current drug regimen for P. vivax is still effective for treating this P. vivax parasite population. Continued surveillance of antimalarial drug resistance markers and monitoring of clinical drug efficacy should be conducted for epidemiological and policy implications.
  5. Rauff-Adedotun AA, Lee IL, Abd Talib N, Shaari N, Yahaya ZS, Meor Termizi FH
    Parasitol Res, 2023 Sep;122(9):2193-2205.
    PMID: 37462745 DOI: 10.1007/s00436-023-07920-5
    Blastocystis is a unicellular, anaerobic protist inhabiting the intestinal tract of diverse animal hosts, including human. Information regarding Blastocystis in small ruminants, namely goats and sheep, is limited globally; thus, this study was carried out to investigate the distribution and determinants of Blastocystis in ruminant livestock animals from Penang, Malaysia. Fecal samples from 127 cattle, 149 goats, and 100 sheep were examined for Blastocystis by in vitro cultivation using modified Jones' medium, while DNA barcoding was used for subtyping. Overall, 23.1% (87/376) of animals screened were positive for Blastocystis sp. The prevalence of infection was significantly higher in goats than in cattle and sheep, while the female gender, semi-intensive farming system, and the Northeast Penang Island district were identified as potential risk factors for Blastocystis infection. Blastocystis sp. ST5, ST14, and ST25 were identified in cattle; ST5, ST10, ST13, and ST14 in goats; and ST4, ST5, ST14, and ST15 in sheep. ST5 and ST14 were found to be the most abundant and widespread subtypes in the study area. To the best of our knowledge, this is the first report of ST4 from sheep and ST13 from goats, thus serving as an update to the host range of Blastocystis sp. ST4 and ST13. The isolation of ST4 and ST5 in this study suggests that ruminant livestock animals could serve as reservoirs of human infection.
  6. Javanshir A, Tavassoli M, Esmaeilnejad B
    Parasitol Res, 2023 Aug;122(8):1873-1881.
    PMID: 37272975 DOI: 10.1007/s00436-023-07888-2
    Trypanosoma evansi, the causative agent of "surra" is enzootic in Iran. The current study aimed to detect T. evansi in horses from different regions of Iran using morphological, serological, and molecular methods. In 2021, 400 blood samples were collected from horses in eight regions. Eighty horses showed clinical signs such as cachexia (n = 64), fever (n = 36), foot edema (n = 40), and abdominal edema (n = 32), and 320 horses appeared healthy. All samples from the studied regions were evaluated for the presence of trypanosomes using direct analysis of blood smears, mercuric chloride, and PCR-based tests. In total, 12% (95% CI: ± 3.1%), 21% (95% CI: ± 3.9%), and 21% (84) of animals were positive for Trypanosoma in microscopic, serologic, and molecular analyses, respectively. All animals positive for SSU rDNA PCR were from Qom, Semnan, and Golestan regions. Further molecular analyses on 84 PCR-positive horses revealed that 29 horses scored positive in PCR using primers of trypanozoon species and 5 scored positive in PCR using primers of Trypanosoma evansi type A. All samples (n = 5) were from Qom region. The 205-bp fragments of T. evansi RoTat 1.2VSG (accession numbers: ON017789-93) analyzed and compared to other isolates sequence from GenBank BLAST search. It has close similarities with isolates from Pakistan, Egypt, Malaysia, Kenya, and India. Data herein demonstrated that horses from Iran were at high risk of T. evansi infection. Comprehensive control programs, such as those based on the application of repellants and traps, and also, compliance with quarantine standards are recommended for minimizing the risk of the infection.
  7. Chang CH, Few LL, Lim BH, Yvonne-Tee GB, Chew AL, See Too WC
    Parasitol Res, 2023 Jul;122(7):1651-1661.
    PMID: 37202563 DOI: 10.1007/s00436-023-07869-5
    The de novo biosynthesis of phosphatidylcholine and phosphatidylethanolamine in Entamoeba histolytica is largely dependent on the CDP-choline and CDP-ethanolamine pathways. Although the first enzymes of these pathways, EhCK1 and EhCK2, have been previously characterized, their enzymatic activity was found to be low and undetectable, respectively. This study aimed to identify the unusual characteristics of these enzymes in this deadly parasite. The discovery that EhCKs prefer Mn2+ over the typical Mg2+ as a metal ion cofactor is intriguing for CK/EK family of enzymes. In the presence of Mn2+, the activity of EhCK1 increased by approximately 108-fold compared to that in Mg2+. Specifically, in Mg2+, EhCK1 exhibited a Vmax and K0.5 of 3.5 ± 0.1 U/mg and 13.9 ± 0.2 mM, respectively. However, in Mn2+, it displayed a Vmax of 149.1 ± 2.5 U/mg and a K0.5 of 9.5 ± 0.1 mM. Moreover, when Mg2+ was present at a constant concentration of 12 mM, the K0.5 value for Mn2+ was ~ 2.4-fold lower than that in Mn2+ alone, without affecting its Vmax. Although the enzyme efficiency of EhCK1 was significantly improved by about 25-fold in Mn2+, it is worth noting that its Km for choline and ATP were higher than in equimolar of Mg2+ in a previous study. In contrast, EhCK2 showed specific activity towards ethanolamine in Mn2+, exhibiting Michaelis-Menten kinetic with ethanolamine (Km = 312 ± 27 µM) and cooperativity with ATP (K0.5 = 2.1 ± 0.2 mM). Additionally, we investigated the effect of metal ions on the substrate recognition of human choline and ethanolamine kinase isoforms. Human choline kinase α2 was found to absolutely require Mg2+, while choline kinase β differentially recognized choline and ethanolamine in Mg2+ and Mn2+, respectively. Finally, mutagenesis studies revealed that EhCK1 Tyr129 was critical for Mn2+ binding, while Lys233 was essential for substrate catalysis but not metal ion binding. Overall, these findings provide insight into the unique characteristics of the EhCKs and highlight the potential for new approaches to treating amoebiasis. Amoebiasis is a challenging disease for clinicians to diagnose and treat, as many patients are asymptomatic. However, by studying the enzymes involved in the CDP-choline and CDP-ethanolamine pathways, which are crucial for de novo biosynthesis of phosphatidylcholine and phosphatidylethanolamine in Entamoeba histolytica, there is great potential to discover new therapeutic approaches to combat this disease.
  8. Tookhy NA, Isa NMM, Mansor R, Rahaman YA, Ahmad NI, Bui DT, et al.
    Parasitol Res, 2023 Jul;122(7):1475-1488.
    PMID: 37145225 DOI: 10.1007/s00436-023-07845-z
    Lymnaeid snails play a crucial role in the transmission of trematode cercariae as an intermediate host that can infect humans, ruminants like buffalo, and other animals, resulting in serious economic losses. The purpose of the study was to identify the morphological and molecular characteristics of snails and cercariae collected from water bodies near buffalo farms that were integrated with palm oil in Perak, Malaysia. The presence or absence of snails in 35 water bodies was examined via cross-sectional study. From three marsh wetlands, 836 lymnaeid snails were gathered in total. Each snail's shell was morphologically identified to determine its family and species. The cercarial stage inside each snail's body was observed using the crushing method and trematode cercariae types were determined. In addition, the target gene Cytochrome c oxidase subunit 1 (Cox1) and the ribosomal internal transcribed spacer 2 (ITS2) region were used to identify the snail species and cercarial types according to the species level. The findings indicated that the collected snails belong to the family lymnaeidae and Radix rubiginosa species. In snails, the cercarial emergence infection rate was 8.7%. Echinostome, xiphidiocercariae, gymnocephalous, brevifurcate-apharyngeate distome cercariae (BADC), and longifurcate-pharyngeal monostome cercariae (LPMC) are the five morphological cercarial types that were observed. The cercariae were identified using morphological and molecular techniques, and they are members of the four families which are Echinostomatidae, Plagiorchiidae, Fasciolidae, and Schistosomatidae. Interestingly, this is the first study on R. rubiginosa and several trematode cercariae in Perak water bodies near buffalo farms that are integrated with palm oil. In conclusion, our research shown that a variety of parasitic trematodes in Perak use R. rubiginosa as an intermediate host.
  9. Kaur CP, Yong CC, Rajamanikam A, Samudi C, Kumar S, Bhassu S, et al.
    Parasitol Res, 2023 Jul;122(7):1463-1474.
    PMID: 37162590 DOI: 10.1007/s00436-023-07842-2
    Blastocystis sp. is an enteric protistan parasite that affects individuals worldwide with gastrointestinal symptoms such as abdominal discomfort, diarrhea, and flatulence. However, its pathogenicity is controversial due to its presence among asymptomatic individuals. Blastocystis sp. subtype 3 (ST3) is the most prevalent subtype among humans that have been associated with irritable bowel syndrome (IBS), Crohn's disease, ulcerative colitis, and colorectal cancer. Axenization of the parasite has been shown to impede its growth thus revealing the importance of accompanying bacteria in ensuring Blastocystis sp. survival. This study aims to identify the influence of accompanying bacteria on the growth of Blastocystis sp. ST3. Blastocystis sp. cultures were treated with Meropenem, Vancomycin, and Amoxicillin-Clavulanic acid (Augmentin). Bacteria-containing supernatant of antibiotic-treated and control cultures were isolated and identified through 16 s rRNA sequencing. Morphological changes of antibiotic-treated Blastocystis sp. ST3 were also observed. The cultures treated with meropenem and augmentin exhibited opposing effects with reduced growth of isolates from symptomatic patients and a significant increase in asymptomatic isolates. Whereas, vancomycin-treated cultures had no difference in the growth of Blastocystis sp. ST3 isolates from symptomatic and asymptomatic patients. Isolates from symptomatic and asymtomatic patients had 6 and 2 distinct bacterial species identified with Proteus mirabilis as the common bacteria among both types of isolates. Morphologically, Blastocystis sp. ST3 cultures exposed to meropenem and augmentin demonstrated an increase in pre-cystic forms. These findings demonstrate the effects of accompanying bacteria on the growth of Blastocystis sp. ST3 that could translate into clinical manifestations observed among Blastocystis sp.-infected patients.
  10. Jajere SM, Lawal JR, Shittu A, Waziri I, Goni MD, Fasina FO
    Parasitol Res, 2023 Feb;122(2):675-684.
    PMID: 36504395 DOI: 10.1007/s00436-022-07748-5
    Ectoparasites of dogs represent an important group of parasites. They often suck blood, cause pruritis, and could serve as vectors of many pathogens of veterinary and public health importance. In northeastern Nigeria, there is a lack of data regarding ectoparasites of dogs. Therefore, this study was undertaken to explore the external parasites of dogs and the associated epidemiological risk factors. A total of 1041 dogs (mean age = 8.5 ± 2.1 months) from residential house visit (54.9%) and those attending veterinary clinic (45.1%) were sampled in northeastern Nigeria. Multivariate logistic regression analysis assessed epidemiological risk factors associated with canine ectoparasitic infections. Of the 1041 dogs screened, 92.5% (963/1047) harbored one or more ectoparasites. Rhipicephalus sanguineus (52.4%), Linognathus setosus (7.8%), Ctenocephalides canis (2.3%), and Otodectes cynotis canis (1.4%) were the significantly encountered tick, lice, fleas, and mite species, respectively. Being female dog (OR = 1.8; p = 0.01), cross (OR = 2.2; p = 0.029), and exotic breeds (OR = 2.4; p = 0.02),  12 months (OR = 2.5; p = 0.03), and dogs used for hunting (OR = 3.2; p = 0.01) and as security guards (OR = 3.8; p = 0.01) were strongly associated with lice infestation. Results from this study revealed a high prevalence of external parasites parasitizing majority of the sampled dogs. Some of these parasites may serve as vectors of zoonotic pathogens posing public health risks.
  11. Attah AO, Sanggari A, Li LI, Nik Him NAII, Ismail AH, Meor Termizi FH
    Parasitol Res, 2023 Jan;122(1):1-10.
    PMID: 36434314 DOI: 10.1007/s00436-022-07731-0
    There has been increasing interest in the study of Blastocystis in the last two decades. Many studies have been carried out in human and animal hosts including environmental sources, but there is little or no information on the occurrence of Blastocystis in water sources worldwide. Therefore, this study aimed at assessing the occurrence of Blastocystis in water sources across the world from 2005 to 2022, noting the method of detection and the distribution of the subtypes from various water sources. A literature search was performed on internet-based databases including Google search, PubMed, Scopus, and Web of Science. Upon application of the criteria for inclusion, 25 articles revealing the occurrence of Blastocystis in water sources in 15 countries were included in the review. Blastocystis occurrence varies across water sources ranging from 0% in a drinking water source in Venezuela to 100% in rivers; well water, stored water, and fishpond in Nepal and Malaysia; and fountain water, irrigation water, and rainwater in Italy, Spain, and Thailand. The occurrence of the parasite was significantly associated with the coliform count, temperature, conductivity, dissolved oxygen, turbidity, total dissolved solids, and chemical oxygen demand. A total of 11 Blastocystis subtypes were identified in water sources worldwide, namely, ST1-ST8, ST10, ST23, and ST26 in which ST1 and ST3 were the most prevalent subtypes. Considering the importance of Blastocystis as a waterborne parasite, the subtype distribution and morphological distinction in water sources need to be carried out using molecular and electron microscopic techniques. Existing studies have covered only about 10% of the world's countries.
  12. Ng YL, Lau YL, Hamid MHA, Jelip J, Ooi CH, Mudin RN, et al.
    Parasitol Res, 2023 Jan;122(1):195-200.
    PMID: 36378331 DOI: 10.1007/s00436-022-07716-z
    Plasmodium knowlesi is a simian malaria parasite that causes significant zoonotic infections in Southeast Asia, particularly in Malaysia. The Plasmodium thrombospondin-related apical merozoite protein (TRAMP) plays an essential role in the invasion of the parasite into its host erythrocyte. The present study investigated the genetic polymorphism and natural selection of the full length PkTRAMP from P. knowlesi clinical isolates from Malaysia. Blood samples (n = 40) were collected from P. knowlesi malaria patients from Peninsular Malaysia and Malaysian Borneo. The PkTRAMP gene was amplified using PCR, followed by cloning into a plasmid vector and sequenced. Results showed that the nucleotide diversity of PkTRAMP was low (π: 0.009). Z-test results indicated negative (purifying) selection of PkTRAMP. The alignment of the deduced amino acid sequences of PkTRAMP of Peninsular Malaysia and Malaysian Borneo revealed 38 dimorphic sites. A total of 27 haplotypes were identified from the amino acid sequence alignment. Haplotype analysis revealed that there was no clustering of PkTRAMP from Peninsular Malaysia and Malaysian Borneo.
  13. Azlan UK, Cheong FW, Lau YL, Fong MY
    Parasitol Res, 2022 Dec;121(12):3443-3454.
    PMID: 36152079 DOI: 10.1007/s00436-022-07665-7
    Plasmodium knowlesi utilizes the Duffy binding protein alpha (PkDBPα) to facilitate its invasion into human erythrocytes. PkDBPα region II (PkDBPαII) from Peninsular Malaysia and Malaysian Borneo has been shown to occur as distinct haplotypes, and the predominant haplotypes from these geographical areas demonstrated differences in binding activity to human erythrocytes in erythrocyte binding assays. This study aimed to determine the effects of genetic polymorphisms in PkDBPαII to immune responses in animal models. The recombinant PkDBPαII (~ 45 kDa) of Peninsular Malaysia (PkDBPαII-H) and Malaysian Borneo (PkDBPαII-S) were expressed in a bacterial expression system, purified, and used in mice and rabbit immunization. The profile of cytokines IL-1ra, IL-2, IL-6, IL-10, TNF-α, and IFN-γ in immunized mice spleen was determined via ELISA. The titer and IgG subtype distribution of raised antibodies was characterized. Immunized rabbit sera were purified and used to perform an in vitro merozoite invasion inhibition assay. The PkDBPαII-immunized mice sera of both groups showed high antibody titer and a similar IgG subtype distribution pattern: IgG2b > IgG1 > IgG2a > IgG3. The PkDBPαII-H group was shown to have higher IL-1ra (P = 0.141) and IL-6 (P = 0.049) concentrations, with IL-6 levels significantly higher than that of the PkDBPαII-S group (P ≤ 0.05). Merozoite invasion inhibition assay using purified anti-PkDBPαII antibodies showed a significantly higher inhibition rate in the PkDBPαII-H group than the PkDBPαII-S group (P ≤ 0.05). Besides, anti-PkDBPαII-H antibodies were able to exhibit inhibition activity at a lower concentration than anti-PkDBPαII-S antibodies. PkDBPαII was shown to be immunogenic, and the PkDBPαII haplotype from Peninsular Malaysia exhibited higher responses in cytokines IL-1ra and IL-6, antibody IgM level, and merozoite invasion inhibition assay than the Malaysian Borneo haplotype. This suggests that polymorphisms in the PkDBPαII affect the level of immune responses in the host.
  14. Madkhali AM, Abdulhaq AA, Atroosh WM, Ghzwani AH, Zain KA, Ghailan KY, et al.
    Parasitol Res, 2021 Nov;120(11):3771-3781.
    PMID: 34561749 DOI: 10.1007/s00436-021-07323-4
    This study investigated the polymorphism in the P. falciparum chloroquine resistance transporter (pfcrt) gene 11 years after chloroquine (CQ) cessation in Jazan region, southwestern Saudi Arabia. Two hundred and thirty-five P. falciparum isolates were amplified to detect mutations in the pfcrt gene. The pfcrt 76 T molecular marker for CQ resistance was detected in 66.4% (156/235) of the isolates, while the K76 CQ-sensitive wild type was detected in 33.6%. The pfcrt 74I and pfcrt 75E point mutations were each found to be present in 56.2% of isolates, while only four isolates (1.7%) were found to carry the pfcrt 72S mutation. Moreover, four pfcrt haplotypes were identified as follows: the CVIET triple-allele (56.2%), SVMET double-allele (1.7%) and CVMNT single-allele (8.5%) mutant haplotypes and the CVMNK wild haplotype (33.6%). The analysis also revealed significant associations between the prevalence of mutant pfcrt alleles and haplotypes and the age group, governorate and nationality of the patients as well as the parasitaemia level (p 
  15. Ya'cob Z, Low VL, Tan TK, Noor-Izwan A, Lourdes EY, Ramli R, et al.
    Parasitol Res, 2021 May;120(5):1555-1561.
    PMID: 33655351 DOI: 10.1007/s00436-021-07087-x
    Sexually anomalous individuals, typically intersexes or gynandromorphs, bear a mixture of male and female traits. Twelve sexually anomalous individuals of the black fly Simulium (Gomphostilbia) trangense Jitklang, Kuvangkadilok, Baimai, Takaoka & Adler were discovered among 49 adults reared from pupae. All 12 sexually anomalous adults were parasitized by mermithid nematodes, although five additional parasitized adults had no overt external anomalies. Sequence analysis of the 18S rRNA gene revealed that the mermithids, possibly representing a new species, are related to Mesomermis spp., with genetic distances of 5.09-6.87%. All 12 anomalous individuals had female phenotypical traits on the head, thorax, forelegs, midlegs, and claws, but male features on the left and right hind basitarsi. One individual had mixed male and female genitalia. The findings are in accord with the trend that mermithid infections are associated with sexually anomalous adult black flies.
  16. Sankari T, Subramanian S, Hoti SL, Pani SP, Jambulingam P, Das PK
    Parasitol Res, 2021 Jan;120(1):311-319.
    PMID: 33146778 DOI: 10.1007/s00436-020-06950-7
    DEC or ivermectin (IVM) in combination with albendazole (ALB) has been the recommended strategy of the Global Programme to Eliminate Lymphatic Filariasis (GPELF) since 2000. Despite effective population coverage (> 65%) with several rounds of MDA with DEC or combination of DEC plus ALB, microfilariae persist in few individuals and they continue to be the source of infection for transmitting LF. We report an individual's variability in response to DEC by defining the response as complete absence of microfilaria (mf) (post-treatment mf count = 0) and non-response as presence of mf (post-treatment mf count ≥ 1). We analyzed follow-up data on individual's response to treatment from two randomized clinical trials in which 46 microfilaremic individuals were treated with single-dose DEC (6 mg/kg body weight). They were classified into low, medium, and high mf density categories based on their pre-treatment mf counts. Of the 46 individuals, 65.2% have not responded throughout the 12-month post-treatment period. Application of a logistic regression model with fixed (age, gender, mf density, post-treatment time, and their interactions) and random (individual's response over time) effects indicated that treatment response is independent of age, gender, and time. The overall treatment response increases in low and decreases in high mf density categories. Furthermore, the estimates for the random coefficients model showed that there is a greater variability in response between individuals over post-treatment time. The results substantiate that individual variation in response to DEC exists which indicate the importance of studying the parasite as well as host genetic factors associated with DEC action.
  17. Rauff-Adedotun AA, Mohd Zain SN, Farah Haziqah MT
    Parasitol Res, 2020 Nov;119(11):3559-3570.
    PMID: 32951145 DOI: 10.1007/s00436-020-06828-8
    Blastocystis is the most frequently observed eukaryotic gastrointestinal symbiont in humans and animals. Its low host specificity and zoonotic potential suggest that animals might serve as possible reservoirs for transmission. The prevalence and subtype distributions of Blastocystis sp. in animal populations in Southeast Asia, a hotspot for zoonotic diseases, are reviewed. Recommendations for future research aimed at understanding the zoonotic role of Blastocystis are also included. Seven countries have, so far, reported Blastocystis infection in various animals, such as livestock, poultry, companion animals, and non-human primates. Pigs were the most studied animals, and there were records of 100% prevalence in pigs, cattle, and ostriches. Using polymerase chain reaction (PCR)-based approaches, twelve Blastocystis sp. subtypes (STs), namely ST1, ST2, ST3, ST4, ST5, ST6, ST7, ST8, ST9, ST10, ST12, and ST14 have been recognised infecting animals of Southeast Asia. ST1 and ST5 were the most frequently identified, and Malaysia observed the most diverse distribution of subtypes. Further investigations on Blastocystis sp. in various animal hosts, using adequate sample sizes and uniform detection methods, are essential for a better understanding of the distribution of this organism. Detailed genome studies, especially on STs shared by humans and animals, are also recommended.
  18. Sahimin N, Meor Termizi FH, Rajamanikam A, Mohd Nazri NA, Govind SK, Mohd Zain SN
    Parasitol Res, 2020 Oct;119(10):3555-3558.
    PMID: 32875397 DOI: 10.1007/s00436-020-06865-3
    Blastocystis sp. is a common enteric parasite of humans and animals associated with inadequate sanitation and poor personal hygiene. Over the years, the Malaysian thriving economy has been facilitated largely by migrant workers from developing countries, and there is concern that diseases endemic to their countries may be imported. Therefore, this study aimed to determine the current status of Blastocystis infection as well as subtypes (STs) from fecal samples among migrant workers in Selangor and Kuala Lumpur, Malaysia. Overall, almost a third of the study cohort (30.9%; n = 68/220) screened were infected with Blastocystis sp. predominantly with ST3 (54.5%; n = 12), followed by ST1 (36.4%; n = 8) and ST2 (9.1%; n = 2). Infection levels was almost similar among the different sectors; manufacturing (32.8%), domestic service (32.3%), and food service (27.3%) with common symptoms for infection included stomach and abdominal pain or discomfort and diarrhea (48.5%; n = 33). None of the socio-demographic risk factors evaluated were significant. Therefore, this study warrants continuous monitoring as well as understanding the impact of transmission among the migrant community with the local population especially those involved in food service sector.
  19. Tan TK, Lim YAL, Chua KH, Chai HC, Low VL, Bathmanaban P, et al.
    Parasitol Res, 2020 Sep;119(9):2851-2862.
    PMID: 32651637 DOI: 10.1007/s00436-020-06790-5
    The field strain of Haemonchus contortus has a long history of anthelmintic resistance. To understand this phenomenon, the benzimidazole resistance profile was characterized from the Malaysian field-resistant strain by integrating phenotypic, genotypic and proteomic approaches. The faecal egg count reduction test (FECRT) demonstrated that benzimidazole resistance was at a critical level in the studied strain. The primary resistance mechanism was attributed to F200Y mutation in the isotype 1 β-tubulin gene as revealed by AS-PCR and direct sequencing. Furthermore, the protein response of the resistant strain towards benzimidazole (i.e., albendazole) treatment was investigated via two-dimensional difference gel electrophoresis (2D-DIGE) and tandem liquid chromatography-mass spectrometry (LC-MS/MS). These investigations illustrated an up-regulation of antioxidant (i.e., ATP-binding region and heat-shock protein 90, superoxide dismutase) and metabolic (i.e., glutamate dehydrogenase) enzymes and down-regulation of glutathione S-transferase, malate dehydrogenase, and other structural and cytoskeletal proteins (i.e., actin, troponin T). Findings from this study are pivotal in updating the current knowledge on anthelmintic resistance and providing new insights into the defence mechanisms of resistant nematodes towards drug treatment.
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