Vector compositions change across forested to deforested ecotones in emerging areas of zoonotic malaria transmission in Malaysia

Hawkes, Frances M.; Manin, Benny Obrain; Cooper, Amanda; Daim, Sylvia; Rahman, Homathevi; Jelip, Jenarun; Husin, Tanrang; Chua, Tock Hing

doi:10.1038/s41598-019-49842-2

Cited by 51 publications

(64 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…donaldi have been implicated in P . knowlesi transmission in other parts of Malaysia [ 2 , 3 , 9 – 14 ]. Evidence suggests that there is substantial heterogeneity in vector diversity and density even between villages only two kilometres apart due to environmental factors such as land-cover, type of agriculture, availability of mosquito breeding sites, temperature, topography and elevation [ 15 – 17 ].…”

Section: Introductionmentioning

confidence: 99%

Human exposure to zoonotic malaria vectors in village, farm and forest habitats in Sabah, Malaysian Borneo

et al. 2020

Self Cite

View full text Add to dashboard Cite

The zoonotic malaria parasite, Plasmodium knowlesi , is now a substantial public health problem in Malaysian Borneo. Current understanding of P . knowlesi vector bionomics and ecology in Sabah comes from a few studies near the epicentre of human cases in one district, Kudat. These have incriminated Anopheles balabacensis as the primary vector, and suggest that human exposure to vector biting is peri-domestic as well as in forest environments. To address the limited understanding of vector ecology and human exposure risk outside of Kudat, we performed wider scale surveillance across four districts in Sabah with confirmed transmission to investigate spatial heterogeneity in vector abundance, diversity and infection rate. Entomological surveillance was carried out six months after a cross-sectional survey of P . knowlesi prevalence in humans throughout the study area; providing an opportunity to investigate associations between entomological indicators and infection. Human-landing catches were performed in peri-domestic, farm and forest sites in 11 villages (3–4 per district) and paired with estimates of human P . knowlesi exposure based on sero-prevalence. Anopheles balabacensis was present in all districts but only 6/11 villages. The mean density of An . balabacensis was relatively low, but significantly higher in farm (0.094/night) and forest (0.082/night) than peri-domestic areas (0.007/night). Only one An . balabacensis (n = 32) was infected with P . knowlesi . Plasmodium knowlesi sero-positivity in people was not associated with An . balabacensis density at the village-level however post hoc analyses indicated the study had limited power to detect a statistical association due low vector density. Wider scale sampling revealed substantial heterogeneity in vector density and distribution between villages and districts. Vector-habitat associations predicted from this larger-scale surveillance differed from those inferred from smaller-scale studies in Kudat; highlighting the importance of local ecological context. Findings highlight potential trade-offs between maximizing temporal versus spatial breadth when designing entomological surveillance; and provide baseline entomological and epidemiological data to inform future studies of entomological risk factors for human P . knowlesi infection.

show abstract

Section: Introductionmentioning

confidence: 99%

Human exposure to zoonotic malaria vectors in village, farm and forest habitats in Sabah, Malaysian Borneo

et al. 2020

Self Cite

View full text Add to dashboard Cite

show abstract

“…donaldi and An. sundaicus collected from Sabah (Malaysia) and the Nicobar and Andaman Islands (India), respectively [63,80]. Apart from these two, our study now reports An.…”

Section: Molecular Characterisation Of Vectorsmentioning

confidence: 56%

“…The high infection rates could also be due to the way sampling was conducted compared to other reported studies [4,[30][31][32]62,63]. Firstly, the current method recovers both sides of the salivary glands without rupturing any to check for sporozoites, increasing the yield of extracted Plasmodium 13 DNA.…”

Section: Identification Of Plasmodiummentioning

confidence: 99%

“…As the PCR amplification prior to cloning amplifies the SSUrRNA genes of all Plasmodium species indiscriminately, the scarcity of any species of Plasmodium DNA in the sample reduces the chance of its amplicon being produced during PCR amplification. The difficulty in obtaining sequencing data of genes of Plasmodium derived from vectors is probably the main reason why previous studies on vectors of knowlesi malaria have only used nested PCR assays [15,30,32,33,63] and for the lack of studies describing the diversity and density of Plasmodium infection in vectors. With an increasing number of zoonotic malaria infections in the world [67][68][69], epidemiological studies of these inadequately studied species within human populations that come into close contact with macaques during activities in the forest and forest-fringe will also be required to monitor potential host-switch events.…”

Section: Accurate Identification Of Plasmodium By Pcr Might Also Be Imentioning

confidence: 99%

See 1 more Smart Citation

New vectors in northern Sarawak, Malaysian Borneo, for the zoonotic malaria parasite, Plasmodium knowlesi

Ang

Kadir

Mohamad

et al. 2020

Preprint

View full text Add to dashboard Cite

Background: The vectors for Plasmodium knowlesi, a significant cause of human malaria in Southeast Asia, identified previously in nature all belong to the Anopheles Leucosphyrus Group. Only one study has been previously undertaken in Sarawak, Malaysian Borneo, to identify vectors of P. knowlesi , where Anopheles latens was incriminated as the vector in Kapit, central Sarawak. A study was therefore undertaken to identify malaria vectors in a different location in Sarawak. Methods: Mosquitoes found landing on humans and resting on leaves over a 5-day period at two sites in the Lawas District of northern Sarawak were collected and identified. DNA samples extracted from salivary glands of Anopheles mosquitoes were subjected to nested PCR malaria-detection assays. The small sub-unit ribosomal RNA (SSUrRNA) genes of Plasmodium , and the internal transcribed spacer 2 (ITSII) and mitochondrial cytochrome c oxidase subunit 1 (COI) sequences of the mosquitoes were derived from the Plasmodium -positive samples for phylogenetic analyses. Results: A total of 65 anophelines and 127 culicines were collected. By PCR, six An. balabacensis and five An. barbirostris Clade VI were found to have single P. knowlesi infecions while three other An. balabacensis had either single, double or triple infections with P. inui, P. fieldi, P. cynomolgi and P. knowlesi . Phylogenetic analyses of the Plasmodium SSUrRNA genes confirmed 3 An. barbirostris Clade VI and 3 An. balabacensis with single P. knowlesi infections, while 3 other An. balabacensis had two or more Plasmodium species of P. inui, P. knowlesi, P. cynomolgi and possibly novel species of Plasmodium . Phylogenies inferred from the ITSII and COI sequences of An. balabacensis and An. barbirostris Clade VI indicate that the former is genetically indistinguishable from An. balabacensis in Borneo while the latter is a novel sibling species belonging to the Anopheles Barbirostris Subgroup. Conclusions: New vectors for P. knowlesi in Sarawak were identified, including An. barbirostris Clade VI , which is a species that does not belong to the Anopheles Leucosphyrus Group.

show abstract

“…As the PCR ampli cation prior to cloning ampli es the SSU rRNA genes of all Plasmodium species indiscriminately, the scarcity of any species of Plasmodium DNA in the sample reduces the chance of its amplicon being produced during PCR ampli cation. The di culty in obtaining sequencing data of genes of Plasmodium derived from vectors is probably the main reason why previous studies on vectors of knowlesi malaria have only used nested PCR assays [15,30,32,33,61] and for the paucity of studies describing the diversity and density of Plasmodium infection in vectors [31,60]. With an increasing number of zoonotic malaria infections worldwide [65][66][67], epidemiological studies of these inadequately studied species within human populations that come into close contact with macaques during activities in the forest and forest-fringe will also be required to monitor potential host-switch events.…”

Section: Diversity and Density Of Plasmodium Infection In Vectorsmentioning

confidence: 99%

New vectors in northern Sarawak, Malaysian Borneo, for the zoonotic malaria parasite, Plasmodium knowlesi

Ang

Kadir

Mohamad

et al. 2020

Preprint

View full text Add to dashboard Cite

Background: Plasmodium knowlesi is a significant cause of human malaria in Sarawak, Malaysian Borneo. Only one study has been previously undertaken in Sarawak to identify vectors of P. knowlesi, where Anopheles latens was incriminated as the vector in Kapit, central Sarawak. A study was therefore undertaken to identify malaria vectors in a different location in Sarawak.Methods: Mosquitoes found landing on humans and resting on leaves over a 5-day period at two sites in the Lawas District of northern Sarawak were collected and identified. DNA samples extracted from salivary glands of Anopheles mosquitoes were subjected to nested PCR malaria-detection assays. The small subunit ribosomal RNA (SSU rRNA) gene of Plasmodium was sequenced, and the internal transcribed spacer 2 (ITS2) and mitochondrial cytochrome c oxidase subunit 1 (cox1) gene of the mosquitoes were sequenced from the Plasmodium-positive samples for phylogenetic analysis.Results: Totals of 65 anophelines and 127 culicines were collected. By PCR, 6 An. balabacensis and 5 An. donaldi were found to have single P. knowlesi infections while 3 other An. balabacensis had either single, double or triple infections with P. inui, P. fieldi, P. cynomolgi and P. knowlesi. Phylogenetic analysis of the Plasmodium SSU rRNA gene confirmed 3 An. donaldi and 3 An. balabacensis with single P. knowlesi infections, while 3 other An. balabacensis had two or more Plasmodium species of P. inui, P. knowlesi, P. cynomolgi and some species of Plasmodium that could not be conclusively identified. Phylogenies inferred from the ITS2 and/or cox1 sequences of An. balabacensis and An. donaldi indicate that they are genetically indistinguishable from An. balabacensis and An. donaldi, respectively, found in Sabah, Malaysian Borneo. Conclusions: Previously An. latens was identified as the vector for P. knowlesi in Kapit, central Sarawak, Malaysian Borneo, and now An. balabacensis and An. donaldi have been incriminated as vectors for zoonotic malaria in Lawas, northern Sarawak.

show abstract

Vector compositions change across forested to deforested ecotones in emerging areas of zoonotic malaria transmission in Malaysia

Cited by 51 publications

References 33 publications

Human exposure to zoonotic malaria vectors in village, farm and forest habitats in Sabah, Malaysian Borneo

Human exposure to zoonotic malaria vectors in village, farm and forest habitats in Sabah, Malaysian Borneo

New vectors in northern Sarawak, Malaysian Borneo, for the zoonotic malaria parasite, Plasmodium knowlesi

New vectors in northern Sarawak, Malaysian Borneo, for the zoonotic malaria parasite, Plasmodium knowlesi

Contact Info

Product

Resources

About