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Patterns and Risk Factors of Soil-Transmitted Helminthiasis Among Orang Asli Subgroups in Peninsular Malaysia

Ngui R, Aziz S, Chua KH, Aidil RM, Lee SC, Tan TK, et al.

Am J Trop Med Hyg, 2015 Aug;93(2):361-70.
PMID: 26055746 DOI: 10.4269/ajtmh.13-0677

A cross-sectional study was conducted to provide comprehensive data on the patterns and associated risk factors of soil-transmitted helminth (STH) infections among five Orang Asli subgroups in Peninsular Malaysia. The overall prevalence of STH infections was 59.9% (95% confidence interval [CI] = 56.1-63.7%). Trichuris trichiura (54.3%; 95% CI = 50.4-58.2%) was the predominant species followed by Ascaris lumbricoides (26.7%; 95% CI = 23.3-30.1%) and hookworm (9.1%; 95% CI = 6.9-11.3%). This study showed diversity for STH infections by subgroup with poverty and personal sanitary behavior as important risk factors for infection. Risk profile analyses indicating that Orang Kuala subgroup who has a generally well-developed infrastructure and better quality of life had a low rate of infection. There is a need for poverty reduction and promotion of deworming programs along with mass scale campaigns to create awareness about health and hygiene to reduce STH infections.

Matched MeSH terms: Soil/parasitology*
Fulltext Evidence for a specific host-endosymbiont relationship between 'Rickettsia sp. genotype RF2125' and Ctenocephalides felis orientis infesting dogs in India

Hii SF, Lawrence AL, Cuttell L, Tynas R, Abd Rani PA, Šlapeta J, et al.

Parasit Vectors, 2015;8:169.
PMID: 25884425 DOI: 10.1186/s13071-015-0781-x

Fleas of the genus Ctenocephalides serve as vectors for a number of rickettsial zoonoses, including Rickettsia felis. There are currently no published reports of the presence and distribution of R. felis in India, however, the ubiquitous distribution of its vector Ctenocephalides felis, makes it possible that the pathogen is endemic to the region. This study investigates the occurrence of Rickettsia spp. infection in various subspecies of C. felis infesting dogs from urban areas of Mumbai, Delhi and Rajasthan in India.

Matched MeSH terms: Dog Diseases/parasitology
Research note: HLA degenerate T-cell epitopes from Plasmodium falciparum liver stage-specific antigen 1 (LSA-1) are highly conserved in isolates from geographically distinct areas

Ravichandran M, Doolan DL, Cox-Singh J, Hoffman SL, Singh B

Parasite Immunol., 2000 Sep;22(9):469-73.
PMID: 10972854

Considerable effort is directed at the development of a malaria vaccine that elicits antigen-specific T-cell responses against pre-erythrocytic antigens of Plasmodium falciparum. Genetic restriction of host T-cell responses and polymorphism of target epitopes on parasite antigens pose obstacles to the development of such a vaccine. Liver stage-specific antigen-1 (LSA-1) is a prime candidate vaccine antigen and five T-cell epitopes that are degenerately restricted by HLA molecules common in most populations have been identified on LSA-1. To define the extent of polymorphism within these T-cell epitopes, the N-terminal non-repetitive region of the LSA-1 gene from Malaysian P. falciparum field isolates was sequenced and compared with data of isolates from Brazil, Kenya and Papua New Guinea. Three of the T-cell epitopes were completely conserved while the remaining two were highly conserved in the isolates examined. Our findings underscore the potential of including these HLA-degenerate T-cell epitopes of LSA-1 in a subunit vaccine.

Matched MeSH terms: Malaria, Falciparum/parasitology
Fulltext The occurence of point mutations in the dihydrofolate reductase-thymidylate synthase (DHFR) gene in Thai isolates of Plasmodium falciparum

Lim PK, Looareesuwan S, Chindanond D, Saleh AM, Tan SK

Southeast Asian J. Trop. Med. Public Health, 1998 Sep;29(3):525-8.
PMID: 10437950
Matched MeSH terms: Malaria, Falciparum/parasitology*
Epidemiology of gastro-intestinal nematodes of sheep in wet tropical conditions in Malaysia

Cheah TS, Rajamanickam C

Trop Anim Health Prod, 1997 Aug;29(3):165-73.
PMID: 9316233

A study on the seasonal variations in the population structure of Haemonchus contortus and Trichostronglyus colubriformis was conducted for a period of 12 months in a typical large scale sheep farm on improved pasture in Peninsular Malaysia which has a wet tropical climate. Successive groups of helminth-free tracer lambs were grazed for 4 weeks together with naturally infected sheep and were necropised for worm counts 2 weeks after their removal from the pasture. The monthly populations of H. contortus fluctuated slightly except in May and August during which more worms were found in the tracer animals. The numbers of T. colubriformis were comparatively high from October to December 1992 and again in March 1993, low during April and June 1992. Small numbers of hypobiotic larvae of H. contortus were detected in the tracer animals. Development and survival of infective larvae of H. contortus and T. colubriformis on pasture were investigated by spreading faeces containing eggs on grass plots in October 1993, February and May 1994. Development of the eggs to the infective larvae occurred within one week and their survival times were 7 weeks in the 3 experiments. The potential for control by rotational grazing is discussed.

Matched MeSH terms: Feces/parasitology
Strongyle infections in sheep and goats under the traditional husbandry system in peninsular Malaysia

Dorny P, Symoens C, Jalila A, Vercruysse J, Sani R

Vet Parasitol, 1995 Jan;56(1-3):121-36.
PMID: 7732637

Faecal egg counts were used to study patterns of trichostrongyle infections in sheep and goats according to season, age, pregnancy and lactation on traditional farms in west Malaysia. Haemonchus contortus and Trichostrongylus spp. were the most important strongyles in sheep and in goats, H. contortus, Trichostrongylus spp. and Oesophagostomum spp. were most prevalent. The faecal egg counts of sheep and goats were apparently not influenced by the small seasonal climatic variations. Strongyle infections were acquired at an earlier age in sheep than in goats. Mean faecal egg counts decreased from the age of 8 months onwards in sheep while in goats this occurred from 12-18 months onwards. A periparturient rise in strongyle egg counts was observed in both animal species. Haemonchus contortus was mainly responsible for this rise in faecal egg counts. The results are discussed with reference to control of gastrointestinal strongyle infections in sheep and goats.

Matched MeSH terms: Pregnancy Complications, Infectious/parasitology
Fulltext Seroprevalence of Sarcoptes scabiei var canis antibodies among aborigines in peninsular Malaysia

Normaznah Y, Saniah K, Nazma M, Mak JW, Krishnasamy M, Hakim SL

Southeast Asian J. Trop. Med. Public Health, 1996 Mar;27(1):53-6.
PMID: 9031401

The Aborigines or Orang Asli in Peninsular Malaysia who are still seminomadic are known to have a close association with dogs. In this study, enzyme-linked immunosorbent assay (ELISA) was used to detect anti-Sarcoptes scabiei var canis antibodies in this community as a measure of exposure to the mite. Out of 312 Orang Asli tested, 24.7% were positive for polyvalent anti-Sarcoptes antibodies. No significant difference was found between the positive rates in males (26.1%) and females (23.6%). Only 1.9% were positive for IgA and none was positive for IgE anti-Sarcoptes antibodies. Since there were very few patients with clinical manifestation of scabies, there is a possibility that continuous exposure to the dogs mite confers cross-protective immunity in the community against human scabies.

Matched MeSH terms: Dogs/parasitology
Recombinant expression of the larval excretory-secretory antigen TES-120 of Toxocara canis in the methylotrophic yeast Pichia pastoris

Fong MY, Lau YL

Parasitol Res, 2004 Jan;92(2):173-6.
PMID: 14655048

A gene encoding the larval excretory-secretory antigen TES-120 of the dog ascarid worm Toxocara canis was cloned into the methylotrophic yeast Pichia pastoris. Specificity of the recombinant TES-120 antigen produced by the yeast was investigated. Forty-five human serum samples from patients infected with different()parasitic organisms, including 8 cases of toxocariasis, were tested against the recombinant antigen in immunoblot assays. Results from the assays showed that the recombinant TES-120 antigen reacted with sera from toxocariasis patients only. This highly specific recombinant TES-120 antigen can potentially be used for the development of an inexpensive serodiagnostic assay for human toxocariasis.

Matched MeSH terms: Toxocariasis/parasitology
Fulltext Malaria resurgence after significant reduction by mass drug administration on Ngodhe Island, Kenya

Kagaya W, Gitaka J, Chan CW, Kongere J, Md Idris Z, Deng C, et al.

Sci Rep, 2019 12 13;9(1):19060.
PMID: 31836757 DOI: 10.1038/s41598-019-55437-8

Although WHO recommends mass drug administration (MDA) for malaria elimination, further evidence is required for understanding the obstacles for the optimum implementation of MDA. Just before the long rain in 2016, two rounds of MDA with artemisinin/piperaquine (Artequick) and low-dose primaquine were conducted with a 35-day interval for the entire population of Ngodhe Island (~500 inhabitants) in Lake Victoria, Kenya, which is surrounded by areas with moderate and high transmission. With approximately 90% compliance, Plasmodium prevalence decreased from 3% to 0% by microscopy and from 10% to 2% by PCR. However, prevalence rebounded to 9% by PCR two months after conclusion of MDA. Besides the remained local transmission, parasite importation caused by human movement likely contributed to the resurgence. Analyses of 419 arrivals to Ngodhe between July 2016 and September 2017 revealed Plasmodium prevalence of 4.6% and 16.0% by microscopy and PCR, respectively. Risk factors for infection among arrivals included age (0 to 5 and 11 to 15 years), and travelers from Siaya County, located to the north of Ngodhe Island. Parasite importation caused by human movement is one of major obstacles to sustain malaria elimination, suggesting the importance of cross-regional initiatives together with local vector control.

Matched MeSH terms: Malaria/parasitology
Bacterial communities in Haemaphysalis, Dermacentor and Amblyomma ticks collected from wild boar of an Orang Asli Community in Malaysia

Lim FS, Khoo JJ, Tan KK, Zainal N, Loong SK, Khor CS, et al.

Ticks Tick Borne Dis, 2020 03;11(2):101352.
PMID: 31866439 DOI: 10.1016/j.ttbdis.2019.101352

Ticks are hematophagous vectors of arthropod-borne disease agents globally. In Malaysia, despite seroprevalence studies indicating the presence of tick-borne diseases among the indigenous people, the etiological agents of these diseases are still unclear. These indigenous people, also known as the Orang Asli, still live in forested areas with frequent contact with wildlife. Wild boar are ubiquitously found in the forested areas where the Orang Asli communities are located and are commonly hunted as a food supplement. In this study, we aim to determine the tick species parasitizing wild boar from an Orang Asli community, and explore the tick-associated bacterial communities using 16 s rRNA amplicon sequencing on the Ion Torrent PGM™ platform. A total of 72 ticks were collected from three wild boar and were morphologically identified as Haemaphysalis hystricis (n = 32), Dermacentor compactus (n = 15), Amblyomma testudinarium (n = 13), Dermacentor steini (n = 10) and Dermacentor atrosignatus (n = 2). Across all tick samples, 910 bacterial taxa were identified. Although the bacterial communities were not significantly distinct between tick species in beta-diversity analyses, Coxiella, Rickettsia and Francisella were detected at high relative abundance in H. hystricis, D. compactus and D. steini respectively. Many other bacterial genera, including those that have been described in many different tick species, were also identified, including Pseudomonas, Acinetobacter, Staphylococcus and Corynebacterium. Beta-diversity analyses also showed that the bacterial communities were separated based on the animal host from which the ticks were collected from, suggesting that the bacterial communities here may be influenced by the animal skin microflora, host blood or the environment. PCR screening confirmed the presence of Rickettsia sp. related to spotted fever group Rickettsia in some of the ticks. This study provides baseline knowledge of the microbiome of H. hystricis, D. atrosignatus, D. compactus, D. steini and A. testudinarium parasitizing wild boar in this region. The information gained in this study provides the basis to target our efforts in H. hystricis, D. compactus and D. steini for the future investigation of vector competence and the zoonotic potential for the Coxiella, Rickettsia and Francisella detected here, as well as their implications for the risks of tick-borne diseases among the Orang Asli communities.

Matched MeSH terms: Swine Diseases/parasitology
Increased sensitivity of malaria detection by nested polymerase chain reaction using simple sampling and DNA extraction

Cox-Singh J, Mahayet S, Abdullah MS, Singh B

Int J Parasitol, 1997 Dec;27(12):1575-7.
PMID: 9467744

Malaria remains a disease of underdeveloped and remote regions of the world. The application of polymerase chain reaction (PCR) technology to malaria epidemiology has the potential for increasing our knowledge and understanding of this disease. In order to study malaria in all geographical locations it is important that specimen collection and DNA extraction for PCR be kept simple. Here we report a method for extracting DNA from dried blood spots on filter paper which is capable of detecting one Plasmodium falciparum and two Plasmodium vivax parasites/microliter of whole blood by nested PCR without compromising the simplicity of specimen collection or DNA extraction.

Matched MeSH terms: Blood/parasitology
Fulltext AIDS-related opportunistic infections in Hospital Kuala Lumpur

Nissapatorn V, Lee C, Quek KF, Abdullah KA

Jpn J Infect Dis, 2003 Oct-Dec;56(5-6):187-92.
PMID: 14695428

We retrospectively reviewed 419 HIV/AIDS patients in Hospital Kuala Lumpur from 1994 to 2001. In the male group, the age range was 20-74, with a mean age 37 years, while in the female group it was 17-63, with a mean age of 33 years. With regard to age group, it was found that the preponderant age group was 25-34 years. The majority of male subjects were Chinese (52.5%), single (56.3%), and unemployed (55.1%), whereas the females were Malay (42.3%), married (79.5%), and non-laborer (64.1%). Also, both groups resided in Kuala Lumpur and had heterosexual contact as the leading cause of HIV transmission. More than half of the patients had CD4 cell counts of <200 cells/cumm. We found that the acquisition of HIV infection via intravenous drug use (IDU) was directly related to the incidence of tuberculosis infection (P < 0.05). Further analysis showed HIV-related tuberculosis with IDU was also dependently correlated with occupational status (unemployed) (P < 0.05). The four main AIDS-defining diseases include tuberculosis (48%), Pneumocystis carinii pneumonia (13%), toxoplasmic encephalitis (11%), and cryptococcal meningitis (7%); in addition, 53% of these patients were found to have CD4 cell counts of less than 200 cells/cumm at the time of diagnosis.

Matched MeSH terms: Encephalitis/parasitology
Fulltext A P. falciparum NF54 Reporter Line Expressing mCherry-Luciferase in Gametocytes, Sporozoites, and Liver-Stages

Marin-Mogollon C, Salman AM, Koolen KMJ, Bolscher JM, van Pul FJA, Miyazaki S, et al.

Front Cell Infect Microbiol, 2019;9:96.
PMID: 31058097 DOI: 10.3389/fcimb.2019.00096

Transgenic malaria parasites expressing fluorescent and bioluminescent proteins are valuable tools to interrogate malaria-parasite biology and to evaluate drugs and vaccines. Using CRISPR/Cas9 methodology a transgenic Plasmodium falciparum (Pf) NF54 line was generated that expresses a fusion of mCherry and luciferase genes under the control of the Pf etramp10.3 gene promoter (line mCherry-luc@etramp10.3). Pf etramp10.3 is related to rodent Plasmodium uis4 and the uis4 promoter has been used to drive high transgene expression in rodent parasite sporozoites and liver-stages. We examined transgene expression throughout the complete life cycle and compared this expression to transgenic lines expressing mCherry-luciferase and GFP-luciferase under control of the constitutive gapdh and eef1a promoters. The mCherry-luc@etramp10.3 parasites express mCherry in gametocytes, sporozoites, and liver-stages. While no mCherry signal was detected in asexual blood-stage parasites above background levels, luciferase expression was detected in asexual blood-stages, as well as in gametocytes, sporozoites and liver-stages, with the highest levels of reporter expression detected in stage III-V gametocytes and in sporozoites. The expression of mCherry and luciferase in gametocytes and sporozoites makes this transgenic parasite line suitable to use in in vitro assays that examine the effect of transmission blocking inhibitors and to analyse gametocyte and sporozoite biology.

Matched MeSH terms: Liver/parasitology
Delineation of BmSXP antibody V-gene usage from a lymphatic filariasis based immune scFv antibody library

Rahumatullah A, Ahmad A, Noordin R, Lim TS

Mol Immunol, 2015 Oct;67(2 Pt B):512-23.
PMID: 26277276 DOI: 10.1016/j.molimm.2015.07.040

Phage display technology is an important tool for antibody generation or selection. This study describes the development of a scFv library and the subsequent analysis of identified monoclonal antibodies against BmSXP, a recombinant antigen for lymphatic filariasis. The immune library was generated from blood of lymphatic filariasis infected individuals. A TA based intermediary cloning approach was used to increase cloning efficiency for the library construction process. A diverse immune scFv library of 10(8) was generated. Six unique monoclonal antibodies were identified from the 50 isolated clones against BmSXP. Analysis of the clones showed a bias for the IgHV3 and Vκ1 (45.5%) and IgHV2 and Vκ3 (27.3%) gene family. The most favored J segment for light chain is IgKJ1 (45.5%). The most favored D and J segment for heavy chain are IgHD6-13 (75%) and IgHJ3 (47.7%). The information may suggest a predisposition of certain V genes in antibody responses against lymphatic filariasis.

Matched MeSH terms: Elephantiasis, Filarial/parasitology*
Fulltext Arthropod Ectoparasites Have Potential to Bind SARS-CoV-2 via ACE

Lam SD, Ashford P, Díaz-Sánchez S, Villar M, Gortázar C, de la Fuente J, et al.

Viruses, 2021 04 19;13(4).
PMID: 33921873 DOI: 10.3390/v13040708

Coronavirus-like organisms have been previously identified in Arthropod ectoparasites (such as ticks and unfed cat flea). Yet, the question regarding the possible role of these arthropods as SARS-CoV-2 passive/biological transmission vectors is still poorly explored. In this study, we performed in silico structural and binding energy calculations to assess the risks associated with possible ectoparasite transmission. We found sufficient similarity between ectoparasite ACE and human ACE2 protein sequences to build good quality 3D-models of the SARS-CoV-2 Spike:ACE complex to assess the impacts of ectoparasite mutations on complex stability. For several species (e.g., water flea, deer tick, body louse), our analyses showed no significant destabilisation of the SARS-CoV-2 Spike:ACE complex, suggesting these species would bind the viral Spike protein. Our structural analyses also provide structural rationale for interactions between the viral Spike and the ectoparasite ACE proteins. Although we do not have experimental evidence of infection in these ectoparasites, the predicted stability of the complex suggests this is possible, raising concerns of a possible role in passive transmission of the virus to their human hosts.

Matched MeSH terms: Ectoparasitic Infestations/parasitology
Molecular detection of tick-borne haemopathogens in shelter dogs and Rhipicephalus sanguineus (sensu lato) ticks from Peninsular Malaysia

Sipin Q, Mustaffa Kamal F, Watanabe M, Megat Abdul Rani PA, Low VL, Abdul Aziz NA

Comp Immunol Microbiol Infect Dis, 2020 Dec;73:101563.
PMID: 33120297 DOI: 10.1016/j.cimid.2020.101563

Ticks are important vectors in transmitting various pathogens and they could jeopardize the health and welfare of humans and animals worldwide. The present study aimed to investigate the presence of important tick-borne haemopathogens (TBH) in dogs and ticks via polymerase chain reaction (PCR) assays. A total of 220 blood samples and 140 ticks were collected from 10 animal shelters in Peninsular Malaysia. Of 220 blood samples, 77 (35 %) were positive to TBH, of which 20 % were E. canis, 12 % were A. platys, 7 % were B. gibsoni and 7 % were B. vogeli. All ticks were identified as Rhipicephalus sanguineus with five samples (3.57 %) positive with TBH. Co-infections of TBH (0.45-9.55 %) in dogs were also observed in this study.

Matched MeSH terms: Dog Diseases/parasitology
Mitochondrial gene content, arrangement and composition compared in African and Asian schistosomes

Le TH, Humair PF, Blair D, Agatsuma T, Littlewood DT, McManus DP

Mol Biochem Parasitol, 2001 Sep 28;117(1):61-71.
PMID: 11551632

Complete sequences were obtained for the coding portions of the mitochondrial (mt) genomes of Schistosoma mansoni (NMRI strain, Puerto Rico; 14 415 bp), S. japonicum (Anhui strain, China; 14 085 bp) and S. mekongi (Khong Island, Laos; 14 072 bp). Each comprises 36 genes: 12 protein-encoding genes (cox1-3, nad1-6, nad4L, atp6 and cob); two ribosomal RNAs, rrnL (large subunit rRNA or 16S) and rrnS (small subunit rRNA or 12S); as well as 22 transfer RNA (tRNA) genes. The atp8 gene is absent. A large segment (9.6 kb) of the coding region (comprising 14 tRNAs, eight complete and two incomplete protein-encoding genes) for S. malayensis (Baling, Malaysian Peninsula) was also obtained. Each genome also possesses a long non-coding region that is divided into two parts (a small and a large non-coding region, the latter not fully sequenced in any species) by one or more tRNAs. The protein-encoding genes are similar in size, composition and codon usage in all species except for cox1 in S. mansoni (609 aa) and cox2 in S. mekongi (219 aa), both of which are longer than homologues in other species. An unexpected finding in all the Schistosoma species was the presence of a leucine zipper motif in the nad4L gene. The gene order in S. mansoni is strikingly different from that seen in the S. japonicum group and other flatworms. There is a high level of identity (87-94% at both the nucleotide and amino acid levels) for all protein-encoding genes of S. mekongi and S. malayensis. The identity between genes of these two species and those of S. japonicum is less (56-83% for amino acids and 73-79% for nucleotides). The identity between the genes of S. mansoni and the Asian schistosomes is far less (33-66% for amino acids and 54-68% for nucleotides), an observation consistent with the known phylogenetic distance between S. mansoni and the other species.

Matched MeSH terms: Schistosomiasis/parasitology
Fulltext Nutritional status, hemoglobin level and their associations with soil-transmitted helminth infections between Negritos (indigenous) from the inland jungle village and resettlement at town peripheries

Muslim A, Lim YA, Mohd Sofian S, Shaari SA, Mohd Zain Z

PLoS One, 2021;16(1):e0245377.
PMID: 33439889 DOI: 10.1371/journal.pone.0245377

This study compared the current nutritional status, hemoglobin levels and their associations with soil-transmitted helminth (STH) infections between two categories of Negritos (indigenous): (i) Inland Jungle Villages (IJV) (ii) and Resettlement Plan Scheme (RPS) near town peripheries, decades after redevelopment and demarginalization. A total of 416 Negritos (IJV: 149; RPS: 267) was included for nutritional profiling based on anthropometric analysis. However, only 196 (IJV: 64; RPS: 132) individuals consented to blood taking for the hemoglobin (Hb) measurements. Subsequently, the association of undernutrition and anemia with STH infections were determined based on univariate and multivariate logistic regression analyses. The overall prevalence of stunting, wasting, and underweight amongst children and adolescents (n = 343) were 45.8%, 42.3% and 59.1%, respectively. In adults (n = 73), the prevalence of underweight was low (6.8%) but overweight and obese was prominent (26.0%). For anemia (n = 196), an overall prevalence rate of 68.4% were observed with 80% and 70.4% of children aged 2-6 y/o and aged 7-12 y/o, respectively being anemic. Comparatively, the prevalence of underweight (WAZ) was significantly higher in the RPS versus the IJV (P = 0.03) In the IJV, children aged ≤ 6 y/o and having STH poly-parasitism were associated with underweight (P = 0.01) and moderate-severe T. trichiura infection was associated with anemia. Whilst in the RPS, underweight was highly associated with only T. trichiura infection (P = 0.04). Wasting was significantly associated with young children aged ≤10 in both IJV (P = 0.004) and RPS (P = 0.02). Despite efforts in improving provision of facilities and amenities among the indigenous, this study highlighted a high magnitude of nutritional issues among the Negritos especially those in the RPS and their likely association with STH infections and decades of demarginalization. Joint nutritional intervention strategies with mass anti-helminthic treatment are imperative and urgently needed to reduce the undernutrition problems especially among indigenous children.

Matched MeSH terms: Soil/parasitology*
Fulltext Detection of Plasmodium knowlesi, Plasmodium falciparum and Plasmodium vivax using loop-mediated isothermal amplification (LAMP) in a co-endemic area in Malaysia

Piera KA, Aziz A, William T, Bell D, González IJ, Barber BE, et al.

Malar J, 2017 01 13;16(1):29.
PMID: 28086789 DOI: 10.1186/s12936-016-1676-9

BACKGROUND: Plasmodium knowlesi is the most common cause of malaria in Malaysia. However, microscopic diagnosis is inaccurate and rapid diagnostic tests (RDTs) are insufficiently sensitive. PCR is sensitive and specific but not feasible at a district level. Loop-mediated isothermal amplification (LAMP) shows potential with only basic requirements. A commercially available LAMP assay, the Eiken Loopamp™ MALARIA Pan Detection kit, is sensitive for Plasmodium falciparum and Plasmodium vivax, but has not previously been evaluated for P. knowlesi. This study aims to determine the sensitivity of this LAMP assay for detecting P. knowlesi infection.
METHODS: Study participants included 73 uncomplicated malaria patients with PCR species confirmation: 50 P. knowlesi, 20 P. falciparum and 3 P. vivax. Nineteen malaria-negative, non-endemic area controls were also included. The sensitivity of the Eiken Loopamp™ MALARIA Pan Detection kit (Pan LAMP) for detecting each Plasmodium species was evaluated. Sensitivity and specificity of the Eiken Loopamp™ MALARIA Pf Detection kit (Pf LAMP) for P. falciparum were also determined. The limit of detection for each LAMP assay was evaluated, with results compared to PCR. All P. knowlesi patients were also tested by CareStart™ (Pf/VOM) and OptiMAL-IT™ (Pan/Pf) RDTs.
RESULTS: The sensitivity of the Pan LAMP assay was 100% for P. knowlesi (95% CI 92.9-100), P. falciparum (95% CI 83.2-100), and P. vivax (95% CI 29.2-100). The Pf LAMP was 100% sensitive and specific for P. falciparum detection, with all P. knowlesi samples having a negative reaction. LAMP sensitivity was superior to both RDTs, with only 10 and 28% of P. knowlesi samples testing positive to CareStart™ and OptiMAL-IT™, respectively. Limit of detection using the Pan LAMP for both P. knowlesi and P. vivax was 2 parasites/μL, comparable to PCR. For P. falciparum both the Pan LAMP and Pf LAMP demonstrated a limit of detection of 20 parasites/μL.
CONCLUSIONS: The Eiken Loopamp™ MALARIA Pan Detection kit is sensitive for detection of P. knowlesi in low parasitaemia clinical infections, as well as P. falciparum and P. vivax. However, a P. knowlesi-specific field assay in a simpler format would assist correct species identification and initiation of optimal treatment for all malaria patients.

Matched MeSH terms: Malaria/parasitology
Fulltext Development of triplex real-time PCR and detection of Toxoplasma gondii DNA in infected mice tissues and spiked human samples

Rahumatullah A, Khoo BY, Noordin R

Trop Biomed, 2015 Jun;32(2):376-85.
PMID: 26691266 MyJurnal

Toxoplasma gondii is an important pathogen in veterinary and human medicine. In this study, a new multiplex TaqMan real-time PCR for detection of T. gondii DNA was developed. This assay consisted of new sets of primers and probes which targeted B1 gene and ITS-1 region of T. gondii, with Vibrio cholera gene as internal control. The B1 gene primers were designed to detect T. gondii RH strain, while the ITS-1 region primers detected most T. gondii strains. Specificity test using common protozoal and bacterial DNA revealed that the assay was very specific to T. gondii. Standard curves constructed using human body fluids spiked with T. gondii (RH and ME49 strains) showed that the sensitivity of the assay was one parasite, with R² value of 0.975 to 0.999 and efficiency of 97% to 99% for all types of samples. The assay performed on DNA extracted from tissues of mice infected with T. gondii showed that liver contained the highest parasite load for both strains of T. gondii. The multiplex real-time PCR developed in this study would be potentially useful for detection of T. gondii in human and animal samples.

Matched MeSH terms: Toxoplasmosis/parasitology

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