Entomologic investigation of Plasmodium knowlesi vectors in Kuala Lipis, Pahang, Malaysia (original) (raw)
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Malaria Journal, 2008
Background A large focus of human infections with Plasmodium knowlesi, a simian parasite naturally found in long-tailed and pig-tailed macaques was discovered in the Kapit Division of Sarawak, Malaysian Borneo. A study was initiated to identify the vectors of malaria, to elucidate where transmission is taking place and to understand the bionomics of the vectors in Kapit. Methods Three different ecological sites in the forest, farm and longhouse in the Kapit district were selected for the study. Mosquitoes were collected by human landing collection at all sites and at the forest also by monkey-baited-traps situated on three different levels. All mosquitoes were identified and salivary glands and midguts of anopheline mosquitoes were dissected to determine the presence of malaria parasites. Results and Discussions Over an 11-month period, a total of 2,504 Anopheles mosquitoes comprising 12 species were caught; 1,035 at the farm, 774 at the forest and 425 at the longhouse. Anopheles latens (62.3%) and Anopheles watsonii (30.6%) were the predominant species caught in the forested ecotypes, while in the farm Anopheles donaldi (49.9%) and An. latens (35.6%) predominated. In the long house, An. latens (29.6%) and An. donaldi (22.8%) were the major Anopheline species. However, An. latens was the only mosquito positive for sporozoites and it was found to be attracted to both human and monkey hosts. In monkey-baited net traps, it preferred to bite monkeys at the canopy level than at ground level. An. latens was found biting early as 18.00 hours. Conclusion Anopheles latens is the main vector for P. knowlesi malaria parasites in the Kapit District of Sarawak, Malaysian Borneo. The study underscores the relationship between ecology, abundance and bionomics of anopheline fauna. The simio-anthropophagic and acrodendrophilic behaviour of An. latens makes it an efficient vector for the transmission of P. knowlesi parasites to both human and monkey hosts. Go to: Background Malaria parasites in Peninsular Malaysian monkeys were first reported in 1908 [1], but only gained prominence in the 1960's after the accidental discovery [2] that Plasmodium cynomolgi could be transmitted to humans via mosquito bites in the laboratory. This stimulated interest at a time when the Malaria Eradication Programme was initiated by the World Health Organization [3] and it was important to determine if malaria was a zoonosis. Therefore, extensive studies were carried out in Peninsular Malaysia to determine the distribution, prevalence and species of malaria parasites in monkeys and apes and the natural vectors of monkey malaria parasites [4-7]. Instead of uncovering human cynomolgi malaria infections, Plasmodium knowlesi was the first simian malaria parasite found to be infecting humans in nature. The first case was reported in 1965 from the state of Pahang [8], Peninsular Malaysia, followed by a second case five years later acquired from Johore, Peninsular Malaysia [9]. It was postulated that P. knowlesi could be transmitted from monkeys to man and laboratory studies proved that it was possible [10]. However, a large scale study that was initiated in Pahang to investigate whether malaria was a zoonosis, by a group of American and local researchers based at the Institute for Medical Research in Kuala Lumpur, Peninsular Malaysia, concluded that simian malaria in humans was an extremely rare event [11,12]. This was based on their studies in which they collected blood samples from more than 1,100 local residents, pooled the samples and injected them into rhesus monkeys and none of the monkeys contracted malaria. However, in 2004 a large focus of human P. knowlesi infection was reported in the Kapit Division of Sarawak [13]. In that study 71.6% (101/141) of human malaria cases at Kapit Hospital which had been identified by microscopy as single Plasmodium malariae infections were actually P. knowlesi and other non-P. malariae species by nested polymerase chain reaction (PCR) assays. Plasmodium knowlesi is naturally found in long-tailed macaques (Macaca fascicularis), pig-tailed macaques (Macaca nemestrina) [14] and banded leaf monkeys (Presbytis malalophos) [15,16]. Since transmission of this zoonotic parasite to humans is occurring in the Kapit Division of Sarawak, Malaysian Borneo, it is important to identify the vectors so that appropriate measures can be planned and initiated to control the spread of simian malaria in humans. Numerous studies on vectors of human malaria have been carried out in Sarawak [17-20] but none of these have been undertaken in the Kapit District of Sarawak. Several anopheline species incriminated or suspected to transmit monkey malaria parasites in Peninsular Malaysia, such as Anopheles latens, Anopheles balabacensis are also present in Sarawak [21]. Hence, the vectorial status of the anopheline species present in the Kapit Division needs to be ascertained in order to determine if they are competent vectors of simian malaria parasites. Furthermore, the epidemiological data of P. knowlesi infection in humans revealed that infections occur primarily in adults and no clustering of cases occurred within communities that live in communal longhouses, which suggests transmission of P. knowlesi to humans occurred away from the vicinity of the longhouses [13]. Thus the objectives of this study were to determine the vectors of P. knowlesi and other simian malaria parasites in the Kapit Division of Sarawak; and to study the dynamics of these vectors in different ecological sites in order to elucidate the most likely place where transmission was taking place. Preliminary results of this study were reported where An. latens was incriminated as the vector for P. knowlesi [22]. Here detailed results of this eleven-month study on vectors of malaria and their bionomics in the Kapit district of Sarawak, Malaysian Borneo is presented.
Malaria Journal, 2023
Background The recent deforestation for agricultural, mining, and human resettlement has significantly reduced the habitat of many non-human primates (NHPs) in Indonesia and intensifies interaction between the NHPs and humans and thus opening the possibility of pathogen spill-over. The emergence of zoonotic malaria, such as Plasmodium knowlesi, poses an immense threat to the current malaria control and elimination that aims for the global elimination of malaria by 2030. As malaria in humans and NHPs is transmitted by the female Anopheles mosquito, malaria vector control is very important to mitigate the spill-over of the malaria parasite to humans. The present study aims to explore the Anopheles species diversity in human settlements adjacent to the wildlife sanctuary forest in Buton Utara Regency, Southeast Sulawesi, Indonesia, and identify the species that potentially transmit the pathogen from monkey to human in the area. Methods Mosquito surveillance was conducted using larval and adult collection, and the collected mosquitoes were identified morphologically and molecularly using the barcoding markers, cytochrome oxidase subunit I (COI), and internal transcribed species 2 (ITS2) genes. Plasmodium sporozoite carriage was conducted on mosquitoes collected through human landing catch (HLC) and human-baited double net trap (HDNT). Results The results revealed several Anopheles species, such as Anopheles flavirostris (16.6%), Anopheles sulawesi (3.3%), Anopheles maculatus (3.3%), Anopheles koliensis (1.2%), and Anopheles vagus (0.4%). Molecular analysis of the sporozoite carriage using the primate-specific malaria primers identified An. sulawesi, a member of the Leucosphyrus group, carrying Plasmodium inui sporozoite. Conclusions This study indicates that the transmission of zoonotic malaria in the area is possible and alerts to the need for mitigation efforts through a locally-tailored vector control intervention and NHPs habitat conservation.
E3S Web of Conferences
This study was conducted to confirm the Anopheles spp as malaria vector inhabits forested areas in Western Lampung Regency, Sumatra Island, Indonesia. Anopheles spp. were sampled using the human landing catch method at a remote forest habitat. Each caput and thorax of Anopheles balabacensis specimen was placed separately inside a sterilized mortar and the tissue homogenized using a sterile pestle. The total DNA was extracted from the tissues according to QIAamp DNA Mini Kit protocol. The presence of malaria parasites in the mosquitoes was detected using nested PCR by targeting the small subunit ribosomal RNA (SSU rRNA) gene of Plasmodium. A PCR primer pair, rPLU1, and rPLU5, was used in the first PCR reaction, while another pair (Pkr and Pkf) was used in the second PCR reaction for detecting Plasmodium knowlesi. There was only 1 Anopheles balabacensis mosquito caught in a remote forest habitat during this study. The results of the molecular analysis showed a positive result for Plas...
Parasites & vectors, 2015
Recent studies have described natural human infections of the non-human primate parasites Plasmodium knowlesi and Plasmodium cynomolgi. In Southeast Asia, mosquitoes of the Anopheles leucosphyrus group bite both humans and monkeys in the forest and thus offer a possible route for Plasmodium species to bridge the species barrier. In this study we analysed the species composition of malarial sporozoites infecting the salivary glands of Anopheles dirus in order to determine their potential role as bridge vectors of Plasmodium parasites from monkeys to humans. Mosquitoes were collected in the forest and forest fringe area of Khanh Phu commune by human-baited landing collection. Anopheles species were determined on the basis of morphologic features. Sporozoite-infected salivary glands were applied to filter paper and dried in an ambient atmosphere, before storage in closed vials at 4-6 °C. Detection and identification of Plasmodium species in salivary glands were carried out by nested-PC...
Natural human Plasmodium infections in major Anopheles mosquitoes in western Thailand
Parasites & Vectors, 2016
Background: The Thai-Myanmar border is a remaining hotspot for malaria transmission. Malaria transmission in this region continues year-round, with a major peak season in July-August, and a minor peak in October-November. Malaria elimination requires better knowledge of the mosquito community structure, dynamics and vectorial status to support effective vector control. Methods: Adult Anopheles mosquitoes were collected using CDC light traps and cow bait in 7 villages along the Thai-Myanmar border in January 2011-March 2013. Mosquitoes were determined to species by morphological characters. Plasmodium-positivity was determined by circumsporozoite protein ELISA. Results: The 2986 Anopheles mosquitoes collected were assigned to 26 species, with Anopheles minimus sensu lato (s.l.) (40.32 %), An. maculatus s.l. (21.43 %), An. annularis s.l. (14.43 %), An. kochi (5.39 %), An. tessellatus (5.26 %), and An. barbirostris s.l. (3.52 %) being the top six most abundant species. Plasmodium-infected mosquitoes were found in 22 positive samples from 2906 pooled samples of abdomens and heads/thoraxes. Four mosquito species were found infected with Plasmodium: An. minimus s.l., An. maculatus s.l., An. annularis s.l. and An. barbirostris s.l. The infectivity rates of these mosquitoes were 0.76, 0.37, 0.72, and 1.74 %, respectively. Consistent with a change in malaria epidemiology to the predominance of P. vivax in this area, 20 of the 22 infected mosquito samples were P. vivax-positive. The four potential vector species all displayed apparent seasonality in relative abundance. While An. minimus s.l. was collected through the entire year, its abundance peaked in the season immediately after the wet season. In comparison, An. maculatus s.l. numbers showed a major peak during the wet season. The two potential vector species, An. annularis s.l. and An. barbirostris s.l., both showed peak abundance during the transition from wet to dry season. Moreover, An. minimus s.l. was more abundant in indoor collections, whereas An. annularis s.l. and An. barbirostris s.l. were more abundant in outdoor collections, suggesting their potential role in outdoor malaria transmission. Conclusions: This survey confirmed the major vector status of An. minimus s.l. and An. maculatus s.l. and identified An. annularis s.l. and An. barbirostris s.l. as additional vectors with potential importance in malaria transmission after the wet season.
Plasmodium knowlesi in humans, macaques and mosquitoes in peninsular Malaysia
Parasit Vectors, 2008
Background Since a large focus of human infection with Plasmodium knowlesi , a simian malaria parasite naturally found in long-tailed and pig tailed macaques, was reported in Sarawak, Malaysian Borneo, it was pertinent to study the situation in peninsular Malaysia. A study was thus initiated to screen human cases of Plasmodium malariae using molecular techniques, to determine the presence of P. knowlesi in non- human primates and to elucidate its vectors. Methods Nested polymerase chain reaction (PCR) was used to identify all Plasmodium species present in the human blood samples sent to the Parasitology laboratory of Institute for Medical Research. At the same time, non-human primates were also screened for malaria parasites and nested PCR was carried out to determine the presence of P. knowlesi . Mosquitoes were collected from Pahang by human landing collection and monkey-baited-traps situated on three different levels. All mosquitoes were identified and salivary glands and midguts of anopheline mosquitoes were dissected to determine the presence of malaria parasites and nested PCR was carried out on positive glands. Sequencing of the csp genes were carried on P. knowlesi samples from humans, monkeys and mosquitoes, positive by PCR. Results and Discussion Plasmodium knowlesi was detected in 77 (69.37%) of the 111 human samples, 10 (6.90%) of the 145 monkey blood and in 2 (1.7%) Anopheles cracens . Sequence of the csp gene clustered with other P. knowlesi isolates. Conclusion Human infection with Plasmodium knowlesi is occurring in most states of peninsular Malaysia. An. cracens is the main vector. Economic exploitation of the forest is perhaps bringing monkeys, mosquitoes and humans into increased contact. A single bite from a mosquito infected with P. knowlesi is sufficient to introduce the parasite to humans. Thus, this zoonotic transmission has to be considered in the future planning of malaria control
Anopheles dirus co-infection with human and monkey malaria parasites in Vietnam
International Journal for Parasitology, 2009
The feasibility of identifying parasite DNA and specific mRNAs from wild caught Anopheles dirus mosquitoes was assessed using dried mosquito salivary glands preserved on filter paper. We were able to detect Plasmodium falciparum, Plasmodium vivax, Plasmodium malariae and Plasmodium knowlesi DNA by conventional PCR and, furthermore, detected P. falciparum gametocyte-specific genes, pfg377 and pfs16 mRNA, P. knowlesi circumsporozoite protein (CSP) and sporozoite surface protein 2 (SSP2) mRNA by reverse transcription-PCR. Using this technique, we were able to confirm the presence of P. vivax, P. falciparum and P. knowlesi in one particular wild-caught mosquito. These results indicate that P. knowlesi may be transmitted by the primary human malaria vector in forested areas in Vietnam.
Malaria Journal, 2016
Background: Members of the Anopheles punctulatus group dominate Papua, Indonesia and Papua New Guinea (PNG), with a geographic range that extends south through Vanuatu. An. farauti and An. punctulatus are the presumed major vectors in this region. Although this group of species has been extensively studied in PNG and the southern archipelagoes within their range, their distribution, ecology and vector behaviours have not been well characterized in eastern Indonesia. Methods: Mosquitoes were collected in five villages in Jayapura province, Papua, Indonesia using human-landing collections, animal-baited tents and backpack aspirators. Mosquitoes were morphologically typed and then molecularly distinguished based on ribosomal ITS2 sequences and tested for Plasmodium falciparum and P. vivax infection using circumsporozoite ELISA and PCR. Results: The presence and vector status of An. farauti 4 in Papua, Indonesia is confirmed here for the first time. The data indicate that this species is entering houses at a rate that increases its potential to come into contact with humans and act as a major malaria vector. An. farauti 4 was also abundant outdoors and biting humans during early evening hours. Other species collected in this area include An. farauti 1, An. hinesorum, An. koliensis, An. punctulatus, and An. tessellatus. Proboscis morphology was highly variable within each species, lending support to the notion that this characteristic is not a reliable indicator to distinguish species within the An. punctulatus group. Conclusions: The vector composition in Papua, Indonesia is consistent with certain northern areas of PNG, but the behaviours of anophelines sampled in this region, such as early and indoor human biting of An. farauti 4, may enable them to act as major vectors of malaria. Presumed major vectors An. farauti and An. punctulatus were not abundant among these samples. Morphological identification of anophelines in this sample was often inaccurate, highlighting the importance of using molecular analysis in conjunction with morphological investigations to update keys and training tools.
The Southeast Asian journal of tropical medicine and public health, 1987
Human bait collections of biting anopheline mosquitoes were made on five consecutive nights during September 1986 in a remote village located in a heavily forested area of South Kalimantan, Indonesia. Anopheles leucosphyrus and An. balabacensis comprised 97.7% of the total number of specimens collected outside houses in the village. Anopheles balabacensis were slightly fewer in total numbers than leucosphyrus. Mosquitoes were collected simultaneously in the village and the forest on two nights. The numbers of leucosphyrus and balabacensis biting in the forest were small in comparison with the populations encountered in the village. Approximately 75% of the specimens were checked individually for sporozoite infections using ELISA for P. falciparum and P. vivax. Sporozoites of P. falciparum were detected in one specimen of leucosphyrus and one of balabacensis. The sporozoite infection rate was 1.0% for leucosphyrus and 1.3% for balabacensis.
Distribution and behavior of Anopheles maculatus and its potential as a Malaria vector in Indonesia
Epidemiology and Society Health Review (ESHR)
Background: Anopheles maculatus is one of the mosquito species that has been confirmed as a malaria vector in Indonesia. The potential of a mosquito as a vector is influenced by its behavior. Information on the distribution and behavior of An. maculatus needs to be carried out to determine the potential for malaria transmission transmitted by the species in an area. The study aimed to obtain information on the distribution, behavior, and potential of maculatus as a malaria vector in several provinces in Indonesia. Method: Mosquito collection was carried out using human-landing collection, animal-baited trap, cattle-bait, light-trap, and resting morning. A survey of mosquitoes was carried out in 29 provinces in Indonesia. Mosquitoes were identified for the species and detected the blood-sucking behavior with an Enzyme-linked immunosorbent assay and the presence of Plasmodium using a Polymerase Chain Reaction. Results: The results showed that An. maculatus was found in the Riau Island...