scholarly journals Plasmodium knowlesi invasion following spread by infected mosquitoes, macaques and humans

Parasitology ◽  
2017 ◽  
Vol 145 (1) ◽  
pp. 101-110 ◽  
Author(s):  
LAITH YAKOB ◽  
ALUN L. LLOYD ◽  
ROWLAND R. KAO ◽  
HEATHER M. FERGUSON ◽  
PATRICK M. BROCK ◽  
...  
Keyword(s):  
Host Species ◽  
Plasmodium Knowlesi ◽  
Behavioural Plasticity ◽  
Biological Processes ◽  
Local Conditions ◽  
Transmission Potential ◽  
Imported Infection ◽  
Natural Hosts ◽  
Invasion Analysis ◽  
Local Vectors

SUMMARYPlasmodium knowlesi is increasingly recognized as a major cause of malaria in Southeast Asia. Anopheles leucosphyrous group mosquitoes transmit the parasite and natural hosts include long-tailed and pig-tailed macaques. Despite early laboratory experiments demonstrating successful passage of infection between humans, the true role that humans play in P. knowlesi epidemiology remains unclear. The threat posed by its introduction into immunologically naïve populations is unknown despite being a public health priority for this region. A two-host species mathematical model was constructed to analyse this threat. Global sensitivity analysis using Monte Carlo methods highlighted the biological processes of greatest influence to transmission. These included parameters known to be influential in classic mosquito-borne disease models (e.g. vector longevity); however, interesting ecological components that are specific to this system were also highlighted: while local vectors likely have intrinsic preferences for certain host species, how plastic these preferences are, and how this is shaped by local conditions, are key determinants of parasite transmission potential. Invasion analysis demonstrates that this behavioural plasticity can qualitatively impact the probability of an epidemic sparked by imported infection. Identifying key vector sub/species and studying their biting behaviours constitute important next steps before models can better assist in strategizing disease control.

scholarly journals Bioactivity—Symphony or Cacophony? A Personal View of a Tangled Field

Prosthesis ◽  
2021 ◽  
Vol 3 (1) ◽  
pp. 75-84
Author(s):  
Brian W Darvell
Keyword(s):  
Active Material ◽  
Biological Processes ◽  
Personal View ◽  
Local Conditions ◽  
Real Progress ◽  
Scientific Sense

In the pursuit of better treatments, the concept of a chemically-active material, responding to local conditions by causing reactions, or reacting to produce substances that are deemed beneficial, seems laudable. Ultimately, the goal appears to be to recruit natural biological processes such that a natural ‘repair’ is effected. This goal seems to be the reason for prefixing “bio-” to many terms with a view to advertising the desire, yet without presenting evidence that it has occurred, or indeed that it is capable of occurring, relying instead on non-biological processes to justify the claims. The dogma is such that all work where local ‘responsive’ chemistry is involved must receive the label “bioactive” to legitimize and promote. Nevertheless, the primary evidence adduced is flawed, and the claim must fail. A rethink to restore scientific sense and confidence in the endeavour is essential if real progress is to be made.

Further studies on Carrot virus Y: hosts, symptomatology, search for resistance, and tests for seed transmissibility

2005 ◽  
Vol 56 (8) ◽  
pp. 859 ◽  
Author(s):  
R. A. C. Jones ◽  
L. J. Smith ◽  
B. E. Gajda ◽  
T. N. Smith ◽  
L. J. Latham
Keyword(s):  
Host Species ◽  
Field Survey ◽  
Systemic Infection ◽  
Seed Transmission ◽  
Anethum Graveolens ◽  
Additional Species ◽  
Wild Carrot ◽  
Natural Hosts ◽  
New Locations ◽  
Seed Transmissibility

Carrot virus Y (CarVY) was studied to provide information on its host range and symptoms, identify any alternative natural hosts and sources of host resistance in carrot germplasm, and determine whether it is seed-borne. Twenty-two species belonging to the Apiaceae were inoculated with CarVY by viruliferous aphids in the glasshouse. Systemic infection with CarVY developed in carrot itself, 4 other Daucus species, 5 herbs, 1 naturalised weed, and 2 Australian native plants. When 7 of these host species were exposed to infection in the field, all became infected systemically. In both glasshouse and field, the types of symptoms that developed in infected plants and their severity varied widely from host to host. Following inoculation with infective sap, the virus was detected in inoculated leaves of 1 additional species in the Apiacaeae, and 2 species of Chenopodiaceae. A field survey did not reveal any alternative hosts likely to be important as CarVY infection reservoirs. When 34 accessions of wild carrot germplasm and 16 of other Daucus spp. were inoculated with infective aphids, symptom severity varied widely among accessions but no source of extreme resistance to CarVY was found. Tests on seedlings grown from seed collected from individual infected plants or field plantings (most with CarVY incidences of >92%) of cultivated carrot (34 135 seeds), wild carrot (20 978 seeds), Anethum graveolens (22 921 seeds), and 3 other host species (3304 seeds) did not detect any seed transmission of CarVY. The implications of these results for control of the virus in carrot crops, minimising the losses it causes, and avoiding its introduction to new locations are discussed.

scholarly journals Malaria Parasites in Macaques in Thailand: Stump-Tailed Macaques (Macaca Arctoides) are New Natural Hosts for Plasmodium Knowlesi, P. Inui, P. Coatneyi and P. Fieldi.

2020 ◽  
Author(s):  
Wirasak Fungfuang ◽  
Chanya Udom ◽  
Daraka Tongthainan ◽  
Khamisah Abdul Kadir ◽  
Balbir Singh
Keyword(s):  
Nested Pcr ◽  
Plasmodium Knowlesi ◽  
Sampling Site ◽  
Macaca Arctoides ◽  
Malaria Parasites ◽  
Zoonotic Malaria ◽  
Natural Hosts ◽  
New Locations ◽  
Pcr Assays ◽  
Nested Pcr Assays

Abstract Background:Certain species of macaques are natural hosts ofPlasmodium knowlesi and P. cynomolgi, which can both cause malaria in humans, and P. inui, which can be experimentally transmitted to humans. A significant number of zoonotic malaria cases have been reported in humans throughout Southeast Asia, including Thailand. There have been only two studies undertaken in Thailand to identify malaria parasites in non-human primates in 6 provinces. The objective of this study was to determine the prevalence of P. knowlesi, P. coatneyi, P. cynomolgi, P. inui and P. fieldiin non-human primates from 4 new locations in Thailand. Methods:A total of 93 blood samples from Macaca fascicularis, M. leonina and M. arctoides were collected from four locations in Thailand: 32 were captive M. fascicularisfrom Chachoengsao Province (CHA), 4 were wild M. fascicularis from Ranong Province (RAN), 32 were wildM. arctoidesfromPrachuap Kiri Khan Province (PRA), and 25 were wild M. leoninafrom Nakornratchasima Province (NAK). DNA was extracted from these samples and analysed by nested PCR assays to detect Plasmodium, and subsequently to detectP. knowlesi, P. coatneyi, P. cynomolgi, P. inui and P. fieldi.Results:Twenty-seven of the 93 (29%) samples were Plasmodium-positive by nested PCR assays. Among wild macaques, all 4 M. fascicularis at RAN were infected with malaria parasites followed by 50% of 32 M. arctoides at PRA and 20% of 25 M. leonina at NAK. Only 2 (6.3%) of the 32 captive M. fascicularisat CHA were malaria-positive. All 5 species of Plasmodium were detected and 16 (59.3%) of the 27 macaques had single infections, 9had double and 2 had triple infections.The composition of Plasmodium species in macaques at each sampling site was different. Macaca arctoides from PRA were infected with P. knowlesi, P. coatneyi, P. cynomolgi, P. inui and P. fieldi. Conclusions:The prevalence and species of Plasmodiumvaried among the wild and captive macaques, and betweenmacaques at 4 sampling sites in Thailand. Macaca arctoidesis a new natural host for P. knowlesi, P. inui,P. coatneyi and P. fieldi.

scholarly journals Bioactivity – Symphony or Cacophony?

2021 ◽  
Author(s):  
Brian W Darvell
Keyword(s):  
Active Material ◽  
Biological Processes ◽  
Local Conditions ◽  
Real Progress ◽  
Scientific Sense

In the pursuit of better treatments, the concept of a chemically-active material, responding to local conditions by causing reactions, or reacting to produce substances that are deemed beneficial, seems laudable. Ultimately, the goal appears to be to recruit natural biological processes such that a natural ‘repair’ is effected. This goal seems to be the reason for prefixing “bio-“ to many terms with a view to advertising the desire, yet without presenting evidence that it has occurred, or indeed that it is capable of occurring, relying instead on non-biological processes to justify the claims. The dogma is such that all work where local ‘responsive’ chemistry is involved must receive the label “bioactive” to legitimize and promote. Nevertheless, the primary evidence adduced is flawed, and the claim must fail. A rethink to restore scientific sense and confidence in the endeavour is essential if real progress is to be made.

scholarly journals Admixture in Humans of Two Divergent Plasmodium knowlesi Populations Associated with Different Macaque Host Species

2015 ◽  
Vol 11 (5) ◽  
pp. e1004888 ◽  
Author(s):  
Paul C. S. Divis ◽  
Balbir Singh ◽  
Fread Anderios ◽  
Shamilah Hisam ◽  
Asmad Matusop ◽  
...  
Keyword(s):  
Host Species ◽  
Plasmodium Knowlesi

scholarly journals Malaria parasites in macaques in Thailand: stump-tailed macaques (Macaca arctoides) are new natural hosts for Plasmodium knowlesi, Plasmodium inui, Plasmodium coatneyi and Plasmodium fieldi

2020 ◽  
Author(s):  
Wirasak Fungfuang ◽  
Chanya Udom ◽  
Daraka Tongthainan ◽  
Khamisah Abdul Kadir ◽  
Balbir Singh
Keyword(s):  
Nested Pcr ◽  
Plasmodium Knowlesi ◽  
Sampling Site ◽  
Macaca Arctoides ◽  
Malaria Parasites ◽  
Natural Hosts ◽  
Pcr Assays ◽  
Nested Pcr Assays ◽  
Plasmodium Coatneyi ◽  
Plasmodium Inui

Abstract Background: Certain species of macaques are natural hosts of Plasmodium knowlesi and Plasmodium cynomolgi, which can both cause malaria in humans, and Plasmodium inui, which can be experimentally transmitted to humans. A significant number of zoonotic malaria cases have been reported in humans throughout Southeast Asia, including Thailand. There have been only two studies undertaken in Thailand to identify malaria parasites in non-human primates in 6 provinces. The objective of this study was to determine the prevalence of P. knowlesi, P. cynomolgi, P. inui, Plasmodium coatneyi and Plasmodium fieldi in non-human primates from 4 new locations in Thailand.Methods: A total of 93 blood samples from Macaca fascicularis, Macaca leonina and Macaca arctoides were collected from four locations in Thailand: 32 were captive M. fascicularis from Chachoengsao Province (CHA), 4 were wild M. fascicularis from Ranong Province (RAN), 32 were wild M. arctoides from Prachuap Kiri Khan Province (PRA), and 25 were wild M. leonina from Nakornratchasima Province (NAK). DNA was extracted from these samples and analysed by nested PCR assays to detect Plasmodium, and subsequently to detect P. knowlesi, P. coatneyi, P. cynomolgi, P. inui and P. fieldi.Results: Twenty-seven of the 93 (29%) samples were Plasmodium-positive by nested PCR assays. Among wild macaques, all 4 M. fascicularis at RAN were infected with malaria parasites followed by 50% of 32 M. arctoides at PRA and 20% of 25 M. leonina at NAK. Only 2 (6.3%) of the 32 captive M. fascicularis at CHA were malaria-positive. All 5 species of Plasmodium were detected and 16 (59.3%) of the 27 macaques had single infections, 9 had double and 2 had triple infections. The composition of Plasmodium species in macaques at each sampling site was different. Macaca arctoides from PRA were infected with P. knowlesi, P. coatneyi, P. cynomolgi, P. inui and P. fieldi.Conclusions: The prevalence and species of Plasmodium varied among the wild and captive macaques, and between macaques at 4 sampling sites in Thailand. Macaca arctoides is a new natural host for P. knowlesi, P. inui, P. coatneyi and P. fieldi.

scholarly journals Prevalence of simian malaria parasites in macaques of Singapore

2021 ◽  
Vol 15 (1) ◽  
pp. e0009110
Author(s):  
Meizhi Irene Li ◽  
Diyar Mailepessov ◽  
Indra Vythilingam ◽  
Vernon Lee ◽  
Patrick Lam ◽  
...  
Keyword(s):  
Human Population ◽  
Malaria Parasite ◽  
Parasite Species ◽  
Plasmodium Knowlesi ◽  
Malaria Parasites ◽  
Simian Malaria ◽  
Specific Pcr ◽  
Natural Hosts ◽  
Multiple Species ◽  
Species Specific

Plasmodium knowlesi is a simian malaria parasite currently recognized as the fifth causative agent of human malaria. Recently, naturally acquired P. cynomolgi infection in humans was also detected in Southeast Asia. The main reservoir of both parasites is the long-tailed and pig-tailed macaques, which are indigenous in this region. Due to increased urbanization and changes in land use, there has been greater proximity and interaction between the long-tailed macaques and the general population in Singapore. As such, this study aims to determine the prevalence of simian malaria parasites in local macaques to assess the risk of zoonosis to the general human population. Screening for the presence of malaria parasites was conducted on blood samples from 660 peridomestic macaques collected between Jan 2008 and Mar 2017, and 379 wild macaques collected between Mar 2009 and Mar 2017, using a Pan-Plasmodium-genus specific PCR. Positive samples were then screened using a simian Plasmodium species-specific nested PCR assay to identify the species of parasites (P. knowlesi, P. coatneyi, P. fieldi, P. cynomolgi, and P. inui) present. All the peridomestic macaques sampled were tested negative for malaria, while 80.5% of the 379 wild macaques were infected. All five simian Plasmodium species were detected; P. cynomolgi being the most prevalent (71.5%), followed by P. knowlesi (47.5%), P. inui (42.0%), P. fieldi (32.5%), and P. coatneyi (28.5%). Co-infection with multiple species of Plasmodium parasites was also observed. The study revealed that Singapore’s wild long-tailed macaques are natural hosts of the five simian malaria parasite species, while no malaria was detected in all peridomestic macaques tested. Therefore, the risk of simian malaria transmission to the general human population is concluded to be low. However, this can be better demonstrated with the incrimination of the vectors of simian malaria parasites in Singapore.

scholarly journals Malaria parasites in macaques in Thailand: Stump-tailed macaques (Macaca arctoides) are new natural hosts for Plasmodium knowlesi, P. inui, P. coatneyi and P. fieldi.

2020 ◽  
Author(s):  
Wirasak Fungfuang ◽  
Chanya Udom ◽  
Daraka Tongthainan ◽  
Khamisah Abdul Kadir ◽  
Balbir Singh
Keyword(s):  
Nested Pcr ◽  
Plasmodium Knowlesi ◽  
Sampling Site ◽  
Macaca Arctoides ◽  
Malaria Parasites ◽  
Zoonotic Malaria ◽  
Natural Hosts ◽  
New Locations ◽  
Pcr Assays ◽  
Nested Pcr Assays

Abstract Background: Certain species of macaques are natural hosts of Plasmodium knowlesi and P. cynomolgi, which can both cause malaria in humans, and P. inui, which can be experimentally transmitted to humans. A significant number of zoonotic malaria cases have been reported in humans throughout Southeast Asia, including Thailand. There have been only two studies undertaken in Thailand to identify malaria parasites in non-human primates in 6 provinces. The objective of this study was to determine the prevalence of P. knowlesi, P. coatneyi, P. cynomolgi, P. inui and P. fieldi in non-human primates from 4 new locations in Thailand. Methods: A total of 93 blood samples from Macaca fascicularis, M. leonina and M. arctoides were collected from four locations in Thailand: 32 were captive M. fascicularis from Chachoengsao Province (CHA), 4 were wild M. fascicularis from Ranong Province (RAN), 32 were wild M. arctoides from Prachuap Kiri Khan Province (PRA), and 25 were wild M. leonina from Nakornratchasima Province (NAK). DNA was extracted from these samples and analysed by nested PCR assays to detect Plasmodium, and subsequently to detect P. knowlesi, P. coatneyi, P. cynomolgi, P. inui and P. fieldi.Results: Twenty-seven of the 93 (29%) samples were Plasmodium-positive by nested PCR assays. Among wild macaques, all 4 M. fascicularis at RAN were infected with malaria parasites followed by 50% of 32 M. arctoides at PRA and 20% of 25 M. leonina at NAK. Only 2 (6.3%) of the 32 captive M. fascicularis at CHA were malaria-positive. All 5 species of Plasmodium were detected and 16 (59.3%) of the 27 macaques had single infections, 9 had double and 2 had triple infections. The composition of Plasmodium species in macaques at each sampling site was different. Macaca arctoides from PRA were infected with P. knowlesi, P. coatneyi, P. cynomolgi, P. inui and P. fieldi. Conclusions: The prevalence and species of Plasmodium varied among the wild and captive macaques, and between macaques at 4 sampling sites in Thailand. Macaca arctoides is a new natural host for P. knowlesi, P. inui, P. coatneyi and P. fieldi.

scholarly journals Inter-species transmission of viral hemorrhagic septicemia virus (VHSV) from turbot (Scophthalmus maximus) to rainbow trout (Onchorhynchus mykiss)

2013 ◽  
Vol 94 (4) ◽  
pp. 869-875 ◽  
Author(s):  
Anna A. Schönherz ◽  
Niels Lorenzen ◽  
Katja Einer-Jensen
Keyword(s):  
Rainbow Trout ◽  
Potential Risk ◽  
Host Species ◽  
Fatal Outcome ◽  
Scophthalmus Maximus ◽  
Viral Hemorrhagic Septicemia Virus ◽  
Species Barrier ◽  
Transmission Potential ◽  
Viral Hemorrhagic Septicemia ◽  
Turbot Scophthalmus Maximus

Successful viral infection is a complex mechanism, involving many host–pathogen interactions that developed during coevolution of host and pathogen, and often result in host-species specificity. Nevertheless, many viruses are able to infect several host species and sporadically cross species barriers. The viral hemorrhagic septicemia virus (VHSV), a rhabdovirus with high economic impact on the aquaculture industry, has developed an exceptionally wide host range across marine and freshwater environments. Transmission of VHSV between host species therefore represents a potential risk for aquaculture, which currently is not addressed in biosecurity managements. The objective of this study was to investigate the inter-species transmission potential of VHSV and evaluate whether infected marine wild fish pose a potential risk on marine cultured rainbow trout. A cohabitation infection trial with turbot as donor and rainbow trout as recipient host species was conducted. Turbot were intraperitoneally injected with either a marine-adapted (MA) or a trout-adapted (TA) VHSV isolate and subsequently grouped with naïve rainbow trout. Both VHSV isolates were able to replicate and cause mortality in turbot, while only the TA isolate was able to cross the species barrier and infect rainbow trout with fatal outcome. The results demonstrate that a marine fish species can function as reservoir and transmitter of TA VHSV isolates.

scholarly journals Malaria parasites in macaques in Thailand: stump-tailed macaques (Macaca arctoides) are new natural hosts for Plasmodium knowlesi, Plasmodium inui, Plasmodium coatneyi and Plasmodium fieldi

2020 ◽  
Vol 19 (1) ◽  
Author(s):  
Wirasak Fungfuang ◽  
Chanya Udom ◽  
Daraka Tongthainan ◽  
Khamisah Abdul Kadir ◽  
Balbir Singh
Keyword(s):  
Nested Pcr ◽  
Plasmodium Knowlesi ◽  
Sampling Site ◽  
Macaca Arctoides ◽  
Malaria Parasites ◽  
Natural Hosts ◽  
Pcr Assays ◽  
Nested Pcr Assays ◽  
Plasmodium Coatneyi ◽  
Plasmodium Inui

Abstract Background Certain species of macaques are natural hosts of Plasmodium knowlesi and Plasmodium cynomolgi, which can both cause malaria in humans, and Plasmodium inui, which can be experimentally transmitted to humans. A significant number of zoonotic malaria cases have been reported in humans throughout Southeast Asia, including Thailand. There have been only two studies undertaken in Thailand to identify malaria parasites in non-human primates in 6 provinces. The objective of this study was to determine the prevalence of P. knowlesi, P. cynomolgi, P. inui, Plasmodium coatneyi and Plasmodium fieldi in non-human primates from 4 new locations in Thailand. Methods A total of 93 blood samples from Macaca fascicularis, Macaca leonina and Macaca arctoides were collected from four locations in Thailand: 32 were captive M. fascicularis from Chachoengsao Province (CHA), 4 were wild M. fascicularis from Ranong Province (RAN), 32 were wild M. arctoides from Prachuap Kiri Khan Province (PRA), and 25 were wild M. leonina from Nakornratchasima Province (NAK). DNA was extracted from these samples and analysed by nested PCR assays to detect Plasmodium, and subsequently to detect P. knowlesi, P. coatneyi, P. cynomolgi, P. inui and P. fieldi. Results Twenty-seven of the 93 (29%) samples were Plasmodium-positive by nested PCR assays. Among wild macaques, all 4 M. fascicularis at RAN were infected with malaria parasites followed by 50% of 32 M. arctoides at PRA and 20% of 25 M. leonina at NAK. Only 2 (6.3%) of the 32 captive M. fascicularis at CHA were malaria-positive. All 5 species of Plasmodium were detected and 16 (59.3%) of the 27 macaques had single infections, 9 had double and 2 had triple infections. The composition of Plasmodium species in macaques at each sampling site was different. Macaca arctoides from PRA were infected with P. knowlesi, P. coatneyi, P. cynomolgi, P. inui and P. fieldi. Conclusions The prevalence and species of Plasmodium varied among the wild and captive macaques, and between macaques at 4 sampling sites in Thailand. Macaca arctoides is a new natural host for P. knowlesi, P. inui, P. coatneyi and P. fieldi.

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