129 research outputs found
Flea-borne pathogens in the cat flea Ctenocephalides felis and their association with the mtDNA diversity of the flea hosts
Flea-borne pathogens were screened from 100 individual cat fleas using a PCR approach, of which 38 % were infected with at least one bacterium. Overall, 28 % of the flea samples were positive for Bartonella as inferred from ITS DNA region. Of these, 25 % (7/28) were identified as Bartonella clarridgeiae, 42.9 % (12/28) as Bartonella henselae consisted of two different strains, and 32.1 % (9/28) as Bartonella koehlerae, which was detected for the first time in Malaysia. Sequencing of gltA amplicons detected Rickettsia DNA in 14 % of cat flea samples, all of them identified as Rickettsia asembonensis (100 %). None of the flea samples were positive for Mycoplasma DNA in 16S rRNA gene detection. Four fleas were co-infected with Bartonella and Rickettsia DNAs. Statistical analyses reveal no significant association between bacterial infection and mtDNA diversity of the cat flea. Nevertheless, in all types of pathogen infections, infected populations demonstrated lower nucleotide and haplotype diversities compared to uninfected populations. Moreover, lower haplotype numbers were observed in infected populations
Co-infection of Haemonchus contortus and Trichostrongylus spp. among livestock in Malaysia as revealed by amplification and sequencing of the internal transcribed spacer II DNA region
Background: Haemonchus contortus and Trichostrongylus spp. are reported to be the most prevalent and highly pathogenic parasites in livestock, particularly in small ruminants. However, the routine conventional tool used in Malaysia could not differentiate the species accurately and therefore limiting the understanding of the co-infections between these two genera among livestock in Malaysia. This study is the first attempt to identify the strongylids of veterinary importance in Malaysia (i.e., H. contortus and Trichostrongylus spp.) by amplification and sequencing of the Internal Transcribed Spacer II DNA region. Results: Overall, 118 (cattle: 11 of 98 or 11.2%; deer: 4 of 70 or 5.7%; goats: 99 of 157 or 63.1%; swine: 4 of 91 or 4.4%) out of the 416 collected fecal samples were microscopy positive with strongylid infection. The PCR and sequencing results demonstrated that 93 samples (1 or 25.0% of deer; 92 or 92.9% of goats) contained H. contortus. In addition, Trichostrongylus colubriformis was observed in 75 (75.8% of 99) of strongylid infected goats and Trichostrongylus axei in 4 (4.0%) of 99 goats and 2 (50.0%) of 4 deer. Based on the molecular results, co-infection of H. contortus and Trichostrongylus spp. (H. contortus + T. colubriformis denoted as HTC; H. contortus + T. axei denoted as HTA) were only found in goats. Specifically, HTC co-infections have higher rate (71 or 45.2% of 157) compared to HTA co-infections (3 or 1.9% of 157). Conclusions: The present study is the first molecular identification of strongylid species among livestock in Malaysia which is essential towards a better knowledge of the epidemiology of gastro-intestinal parasitic infection among livestock in the country. Furthermore, a more comprehensive or nationwide molecular-based study on gastro-intestinal parasites in livestock should be carried out in the future, given that molecular tools could assist in improving diagnosis of veterinary parasitology in Malaysia due to its high sensitivity and accuracy
Spatial analyses of Plasmodium knowlesi vectors with reference to control interventions in Malaysia
Background Malaria parasites such as Plasmodium knowlesi, P. inui, and P. cynomolgi are spread from macaques
to humans through the Leucosphyrus Group of Anopheles mosquitoes. It is crucial to know the distribution
of these vectors to implement efective control measures for malaria elimination. Plasmodium knowlesi is the most
predominant zoonotic malaria parasite infecting humans in Malaysia.
Methods Vector data from various sources were used to create distribution maps from 1957 to 2021. A predictive
statistical model utilizing logistic regression was developed using signifcant environmental factors. Interpolation maps were created using the inverse distance weighted (IDW) method and overlaid with the corresponding
environmental variables.
Results Based on the IDW analysis, high vector abundances were found in the southwestern part of Sarawak, the northern region of Pahang and the northwestern part of Sabah. However, most parts of Johor, Sabah, Perlis, Penang, Kelantan and Terengganu had low vector abundance. The accuracy test indicated that the model predicted
sampling and non-sampling areas with 75.3% overall accuracy. The selected environmental variables were entered into the regression model based on their signifcant values. In addition to the presence of water bodies, elevation,
temperature, forest loss and forest cover were included in the fnal model since these were signifcantly correlated.
Anopheles mosquitoes were mainly distributed in Peninsular Malaysia (Titiwangsa range, central and northern parts), Sabah (Kudat, West Coast, Interior and Tawau division) and Sarawak (Kapit, Miri, and Limbang). The predicted Anopheles mosquito density was lower in the southern part of Peninsular Malaysia, the Sandakan Division of Sabah and the western region of Sarawak.
Conclusion The study ofers insight into the distribution of the Leucosphyrus Group of Anopheles mosquitoes in Malaysia. Additionally, the accompanying predictive vector map correlates well with cases of P. knowlesi malaria. This
research is crucial in informing and supporting future eforts by healthcare professionals to develop efective malaria control interventions
Correction : Pramasivan et al. Multiplex PCR Assay for the Identification of Four Species of the Anopheles Leucosphyrus Sub-Group in Malaysia. Insects 2022, 13, 195
Cryptic Diversity and Demographic Expansion of Plasmodium knowlesi Malaria Vectors in Malaysia
Although Malaysia is considered free of human malaria, there has been a growing number
of Plasmodium knowlesi cases. This alarming trend highlighted the need for our understanding of
this parasite and its associated vectors, especially considering the role of genetic diversity in the
adaptation and evolution among vectors in endemic areas, which is currently a significant knowledge
gap in their fundamental biology. Thus, this study aimed to investigate the genetic diversity of
Anopheles balabacensis, Anopheles cracens, Anopheles introlatus, and Anopheles latens—the vectors for
P. knowlesi malaria in Malaysia. Based on cytochrome c oxidase 1 (CO1) and internal transcribed
spacer 2 (ITS2) markers, the genealogic networks of An. latens showed a separation of the haplotypes
between Peninsular Malaysia and Malaysia Borneo, forming two distinct clusters. Additionally,
the genetic distances between these clusters were high (2.3–5.2% for CO1) and (2.3–4.7% for ITS2),
indicating the likely presence of two distinct species or cryptic species within An. latens. In contrast,
no distinct clusters were observed in An. cracens, An. balabacensis, or An. introlatus, implying a lack
of pronounced genetic differentiation among their populations. It is worth noting that there were
varying levels of polymorphism observed across the different subpopulations, highlighting some
levels of genetic variation within these mosquito species. Nevertheless, further analyses revealed
that all four species have undergone demographic expansion, suggesting population growth and
potential range expansion for these vectors in this regio
Co-infection of Haemonchus contortus and Trichostrongylus spp. among livestock in Malaysia as revealed by amplification and sequencing of the internal transcribed spacer II DNA region
Background: Haemonchus contortus and Trichostrongylus spp. are reported to be the most prevalent and highly
pathogenic parasites in livestock, particularly in small ruminants. However, the routine conventional tool used in
Malaysia could not differentiate the species accurately and therefore limiting the understanding of the co-infections
between these two genera among livestock in Malaysia. This study is the first attempt to identify the strongylids of
veterinary importance in Malaysia (i.e., H. contortus and Trichostrongylus spp.) by amplification and sequencing of
the Internal Transcribed Spacer II DNA region.
Results: Overall, 118 (cattle: 11 of 98 or 11.2%; deer: 4 of 70 or 5.7%; goats: 99 of 157 or 63.1%; swine: 4 of 91 or
4.4%) out of the 416 collected fecal samples were microscopy positive with strongylid infection. The PCR and
sequencing results demonstrated that 93 samples (1 or 25.0% of deer; 92 or 92.9% of goats) contained H. contortus.
In addition, Trichostrongylus colubriformis was observed in 75 (75.8% of 99) of strongylid infected goats and
Trichostrongylus axei in 4 (4.0%) of 99 goats and 2 (50.0%) of 4 deer. Based on the molecular results, co-infection of
H. contortus and Trichostrongylus spp. (H. contortus + T. colubriformis denoted as HTC; H. contortus + T. axei denoted
as HTA) were only found in goats. Specifically, HTC co-infections have higher rate (71 or 45.2% of 157) compared to
HTA co-infections (3 or 1.9% of 157).
Conclusions: The present study is the first molecular identification of strongylid species among livestock in
Malaysia which is essential towards a better knowledge of the epidemiology of gastro-intestinal parasitic infection
among livestock in the country. Furthermore, a more comprehensive or nationwide molecular-based study on
gastro-intestinal parasites in livestock should be carried out in the future, given that molecular tools could assist in improving diagnosis of veterinary parasitology in Malaysia due to its high sensitivity and accurac
Dimorphic male scutal patterns and uppereye facets of Simulium mirum n. sp. (Diptera: Simuliidae) from Malaysia
Background: A species of Simulium in the Simulium melanopus species-group of the subgenus Simulium (formerly misidentified as S. laterale Edwards from Sabah and Sarawak, Malaysia) is suspected to have dimorphic male scutal color patterns linked with different numbers of upper-eye facets. This study aimed to confirm whether or not these two forms of adult males represent a single species. Methods: DNA sequences generated from four genetic loci, the mitochondrial-encoded COI, COII, 12S rRNA and 16S rRNA genes, of both forms of Simulium sp. males were compared with each other and also with those of the females and larvae of the same species. Four other related Simulium spp. were also used for comparison. Results: Both the concatenated dataset and single-locus phylogenetic analyses indicate that the two distinct morphological males of Simulium sp. are indeed conspecific, and represent, together with their associated females and larvae, a distinct species. Conclusions: Based on DNA analyses, Simulium sp. is proven to show dimorphism in males and is herein described as a new species, Simulium mirum Takaoka, Sofian-Azirun & Low. This is the first report of such a novel species among the family Simuliidae
DNA barcodes and species boundaries of black flies (Diptera: Simuliidae) in Malaysia
Black flies play a prominent role in public health and the epidemiology of parasitic diseases of humans, domesticated and wild animals. Correct identification and a comprehensive survey are required to identify vector and pest species and thus understand their biological attributes which play a vital role in the monitoring program. DNA barcoding is an established molecular tool that provides rapid and accurate species identification. Our study strengthens the molecular database for black flies in Malaysia by adding 59 cytochrome c oxidase I sequences for 22 species, of which 14 are included for the first time. These sequences, combined with those in public databases, represent a total of 338 sequences for 52 Malaysian species, nearly 50% of which were collected from type localities. At the subgeneric level, barcode gap analysis most accurately identified species in the subgenus Nevermannia (92%), followed by Simulium s. l. (91%), and Gomphostilbia (81%). The remaining sequences were ambiguous and could not be distinguished from those of nearest neighbour species due to an overlap in genetic divergence and low genetic diversity, especially between insular species. Tree analyses indicate that certain species had incomplete lineage sorting and low mitochondrial signals. Possible cryptic species were indicated in the Simulium (Gomphostilbia) batoense and S. (G.) epistum species groups. Species delimitations were consistent with morphological identifications except in large species groups such as the S. (G.) asakoae, S. (G.) batoense, S. (G.) epistum, and S. (Simulium) melanopus groups. The use of type specimens or specimens collected from type localities (topotypes) in barcoding is strongly recommended for reference sequences to increase the reliability of the molecular database
Organophosphate and organochlorine resistance in larval stage of aedes albopictus (Diptera: Culicidae) in Sabah, Malaysia
The present study aims to investigate the susceptibility status of Aedes albopictus (Skuse) collected from residential areas in Sabah, Malaysia towards eight WHO-recommended dosages of larvicides representing the classes of organophosphates and organochlorines. Field and reference strains of Ae. albopictus larvae were bioassayed in accordance to WHO standard methods using diagnostic dosages of bromophos, malathion, fenthion, fenitrothion, temephos, chlorpyrifos, dichlorodiphenyltrichloroethane (DDT), and dieldrin. The results revealed that Ae. albopictus was resistant (mortality < 90%) towards malathion, temephos, and DDT. In addition, most of the Ae. albopictus strains exhibited a wide range of susceptibilities against bromophos, with mortality ranged from 49.33 to 93.33%. On the contrary, only dieldrin was able to induce 100% mortality against all strains of Ae. albopictus. Tolerance to fenitrothion, fenthion, and chlorpyrifos, with mortality ranging from 81.33 to 97.33%, was also observed in this study
Three Taxa in One: Cryptic Diversity in the Black Fly Simulium nobile (Diptera: Simuliidae) in Southeast Asia
We access the molecular diversity of the black fly Simulium nobile De Mejiere, using the universal cytochrome c oxidase subunit I (COI) barcoding gene, across its distributional range in Southeast Asia. Our phylogenetic analyses recovered three well-supported mitochondrial lineages of S. nobile , suggesting the presence of cryptic species. Lineage A is composed of a population from Sabah, East Malaysia (Borneo); lineage B represents the type population from Java, Indonesia; and lineage C includes populations from the mainland of Southeast Asia (Peninsular Malaysia and Thailand). The genetic variation of lineage C on the mainland is greater than that of lineages A and B on the islands of Borneo and Java. Our study highlights the value of a molecular approach in assessing species status of simuliids in geographically distinct regions
- …