Plasmodium knowlesi Gametocyte Carriage among Malaria Patients in Kapit
| dc.contributor.author | Darvindran A/L Theivindran | |
| dc.date.accessioned | 2026-07-21T01:56:09Z | |
| dc.date.issued | 2022 | |
| dc.description | Plasmodium knowlesi¸ a malaria parasite typically found in long-tailed and pig-tailed macaques, is the main cause of malaria in humans in Sarawak, Malaysian Borneo. The reasons for the recent increase in knowlesi malaria in Malaysia in multifactorial and could include human-to-human transmission through mosquito bites. Such transmission would require viable gametocytes circulating in the blood of infected individuals as this is the only blood stage transmissible to mosquitoes. The objectives of this study were to determine the proportion of knowlesi malaria patients with viable gametocytes and to determine the association between gametocyte carriage and duration of illness prior to hospital admission. Between 2016 and 2018, venous blood samples were collected from 295 adult patients at Kapit Hospital and stored frozen in RNAprotect®. Parasitaemia was determined via microscopy with the use of thick blood films. Upon RNA extraction from blood samples and cDNA generation, samples were subjected to PCR targeting a housekeeping gene (pk serine tRNA ligase) to assess successful cDNA synthesis. Messenger RNA (mRNA) transcripts of pks25, a gene expressed in mature P. knowlesi gametocytes, were then measured by a real-time PCR assay. A standard dilution series of a plasmid harbouring the pks25 sequence were included in each assay run to ascertain gametocyte density. Negative samples were validated by re-extracting and re-screening samples. Sensitivity and efficiency of assay were reported to be 1 transcript copy/μL and 92%, respectively. Datasets were non-normally distributed, hence tested using non-parametric tests. Viable gametocytes were prevalent in 67.5% (199/295) of the patients and appeared in the blood of 43.7% (87/199) of gametocyte-positive patients who had been ill between 2-3 days before hospital admission. A positive correlation was observed between gametocyte carriage and parasitaemia (ρ=0.31, p<0.05); via Spearman’s correlation test. A positive correlation was also seen between gametocyte iv carriage and duration of illness (ρ=0.28, p<0.05). Taken together with studies in the 1960s that show knowlesi malaria can be transmitted experimentally through mosquitoes from on infected person to 7 others, our findings that viable gametocytes are present and occur fairly early in the infection indicated that human-to-human transmission by mosquitoes is possible and could be occurring. | |
| dc.identifier.uri | https://scholarhub.unimas.my/handle/123456789/1224 | |
| dc.language.iso | English | |
| dc.publisher | UNIVERSITI MALAYSIA SARAWAK | |
| dc.relation.ispartofseries | Faculty of Medicine and Health Sciences | |
| dc.subject | Malaria, Plasmodium knowlesi, gametocytes, duration of illness | |
| dc.title | Plasmodium knowlesi Gametocyte Carriage among Malaria Patients in Kapit | |
| dc.type | Masters |