MyMedR

Displaying publications 41 - 54 of 54 in total

Abstract:

Sort:

Fulltext Plasmodium knowlesi malaria an emerging public health problem in Hulu Selangor, Selangor, Malaysia (2009-2013): epidemiologic and entomologic analysis

Vythilingam I, Lim YA, Venugopalan B, Ngui R, Leong CS, Wong ML, et al.

Parasit Vectors, 2014;7:436.
PMID: 25223878 DOI: 10.1186/1756-3305-7-436

While transmission of the human Plasmodium species has declined, a significant increase in Plasmodium knowlesi/Plasmodium malariae cases was reported in Hulu Selangor, Selangor, Malaysia. Thus, a study was undertaken to determine the epidemiology and the vectors involved in the transmission of knowlesi malaria.

Matched MeSH terms: Anopheles/parasitology*
Natural transmission of Plasmodium knowlesi to humans by Anopheles latens in Sarawak, Malaysia

Vythilingam I, Tan CH, Asmad M, Chan ST, Lee KS, Singh B

Trans R Soc Trop Med Hyg, 2006 Nov;100(11):1087-8.
PMID: 16725166

Four species of malaria parasites are known to infect humans. A fifth species, Plasmodium knowlesi, has been reported to infect humans in Malaysian Borneo. Here we report for the first time the incrimination of Anopheles latens as the vector of P. knowlesi among humans and monkeys in Sarawak, Malaysia.

Matched MeSH terms: Anopheles/parasitology*
Epidemiology of malaria in Attapeu Province, Lao PDR in relation to entomological parameters

Vythilingam I, Sidavong B, Chan ST, Phonemixay T, Vanisaveth V, Sisoulad P, et al.

Trans R Soc Trop Med Hyg, 2005 Nov;99(11):833-9.
PMID: 16112154

Surveys were conducted in malaria-endemic villages in the southern province of Attapeu, Lao PDR during various seasons over a 3-year period. All-night mosquito landing collections, blood surveys and a case-control study were conducted. Plasmodium falciparum was the predominant species, and slide positivity rates were higher during the transition/dry season compared with the wet season. Anopheles dirus A was found to be the primary vector, and sporozoite rates were highest during the transition/dry season. Anopheles dirus was found to be endophagic and endophilic. Not using insecticide-treated bed nets, houses close to breeding sites and sleeping away from home were risk factors associated with malaria.

Matched MeSH terms: Anopheles/parasitology
The impact of development and malaria control activities on its vectors in the Kinabatangan area of Sabah, East Malaysia

Vythilingam I, Chan ST, Shanmugratnam C, Tanrang H, Chooi KH

Acta Trop, 2005 Oct;96(1):24-30.
PMID: 16076459

A study was carried out from July 2001 until January 2003 in the Kinabatangan area of Sabah, part of Borneo island, where malaria used to be mesoendemic. Vector surveys determined that Plasmodium falciparum was the predominant species and Anopheles balabacensis the primary vector. Malaria cases have dropped drastically over the years but P. falciparum is still predominant. In the present study, Anopheles donaldi was the predominant species and was positive for sporozoites. Although An. balabacensis was present, none were infective. An. donaldi bite more outdoors than indoors and have a peak biting time from 18:00 to 19:00 h when most people are still out of their homes. An integrated malaria control programme along with area development has helped in the control of malaria and its vector.

Matched MeSH terms: Anopheles/parasitology*
Current status of Plasmodium knowlesi vectors: a public health concern?

Vythilingam I, Wong ML, Wan-Yussof WS

Parasitology, 2018 01;145(1):32-40.
PMID: 27222102 DOI: 10.1017/S0031182016000901

Plasmodium knowlesi a simian malaria parasite is currently affecting humans in Southeast Asia. Malaysia has reported the most number of cases and P. knowlesi is the predominant species occurring in humans. The vectors of P. knowlesi belong to the Leucosphyrus group of Anopheles mosquitoes. These are generally described as forest-dwelling mosquitoes. With deforestation and changes in land-use, some species have become predominant in farms and villages. However, knowledge on the distribution of these vectors in the country is sparse. From a public health point of view it is important to know the vectors, so that risk factors towards knowlesi malaria can be identified and control measures instituted where possible. Here, we review what is known about the knowlesi malaria vectors and ascertain the gaps in knowledge, so that future studies could concentrate on this paucity of data in-order to address this zoonotic problem.

Matched MeSH terms: Anopheles/parasitology
Fulltext A highly sensitive, nested polymerase chain reaction based method using simple dna extraction to detect malaria sporozoites in mosquitos

Vythilingam I, Nitiavathy K, Yi P, Bakotee B, Hugo B, Singh B, et al.

Southeast Asian J. Trop. Med. Public Health, 1999 Dec;30(4):631-5.
PMID: 10928352

Dried Anopheles farauti mosquitos caught in Solomon Islands in 1990 were examined for malaria sporozoites by ELISA and nested polymerase chain reaction (PCR). Only heads and thoraces were used. Plasmodium genus-specific nested PCR amplifications were carried out on all samples. Of the 402 pools of mosquitos that were processed, 30 were positive for malaria. Nest 1 products of positive samples were subjected to further PCR amplifications with species-specific primers for P. falciparum and P. vivax. Twenty pools were positive for P. vivax by PCR while only 7 were positive by ELISA. For P. falciparum 2 pools were positive by both ELISA and PCR, and one of these was a pool which was positive for P. vivax by PCR and ELISA. Thus the sensitivity of PCR for P. vivax was 100% while the specificity was 96.7%. For P. falciparum the sensitivity and specificity were 100%. The PCR technique is highly sensitive and can be used on dried mosquitos which makes it a valuable tool for determining sporozoite rates of mosquitos, even in remote areas.

Matched MeSH terms: Anopheles/parasitology*
The prevalence of Anopheles (Diptera: Culicidae) mosquitoes in Sekong Province, Lao PDR in relation to malaria transmission

Vythilingam I, Phetsouvanh R, Keokenchanh K, Yengmala V, Vanisaveth V, Phompida S, et al.

Trop Med Int Health, 2003 Jun;8(6):525-35.
PMID: 12791058

A longitudinal study was conducted on the prevalence of Anopheles in three malaria endemic villages in Sekong province, in the southern region of Lao PDR, from August 2000 to October 2001. All night, human landing collections took place in August and October 2000 and April and October 2001, and blood smears were taken for malaria parasites during the same period. Mosquitoes were tested for sporozoite antigen using enzyme-linked immunosorbent assay. In August 2000 (wet season) and April 2001 (dry season) the ovaries of the mosquitoes were examined for parity. A total of 16 species of Anopheles were caught in the study sites of which An. dirus A, An. maculatus sl and An. jeyporiensis were positive for sporozoites. The entomological inoculation rate (EIR) ranged from 0.06 to 0.25. There was a good correlation between EIR and vectorial capacity in the wet season, especially in Pai Mai where the prevalence of malaria was also high during the wet seasons (11.8 and 10.53). An. dirus A showed ambivalence in their choice of feeding as approximately 50% attacked man indoors and an equal proportion outdoors. An dirus A was the main vector in Pai Mai. The parous rate did not significantly differ between the wet and dry season, although it was higher in the dry season. In Takaio the parasite prevalence ranged from 8.7% (dry season) to 37.1% (wet season) and An. jeyporiensis was the vector, and the risk of infection was 0.85 in the dry season while 0.99 in the wet season. In Toumgno An. maculatus sl was the vector and infection was found only in August and October 2000. However, malaria prevalence ranged from 9.69 to 20.4% and was equally high in the dry season. Cattle were also present close to the houses in all the villages and this might be a contributory factor in the prevalence of malaria.

Matched MeSH terms: Anopheles/parasitology*
Fulltext Plasmodium knowlesi in humans: a review on the role of its vectors in Malaysia

Vythilingam I

Trop Biomed, 2010 Apr;27(1):1-12.
PMID: 20562807 MyJurnal

Plasmodium knowlesi in humans is life threatening, is on the increase and has been reported from most states in Malaysia. Anopheles latens and Anopheles cracens have been incriminated as vectors. Malaria is now a zoonoses and is occurring in malaria free areas of Malaysia. It is also a threat to eco-tourism. The importance of the vectors and possible control measures is reviewed here.

Matched MeSH terms: Anopheles/parasitology*
Fulltext Plasmodium knowlesi: the fifth human malaria parasite

White NJ

Clin Infect Dis, 2008 Jan 15;46(2):172-3.
PMID: 18171246 DOI: 10.1086/524889
Matched MeSH terms: Anopheles/parasitology
Fulltext Seasonal and Spatial Dynamics of the Primary Vector of Plasmodium knowlesi within a Major Transmission Focus in Sabah, Malaysia

Wong ML, Chua TH, Leong CS, Khaw LT, Fornace K, Wan-Sulaiman WY, et al.

PLoS Negl Trop Dis, 2015;9(10):e0004135.
PMID: 26448052 DOI: 10.1371/journal.pntd.0004135

BACKGROUND: The simian malaria parasite Plasmodium knowlesi is emerging as a public health problem in Southeast Asia, particularly in Malaysian Borneo where it now accounts for the greatest burden of malaria cases and deaths. Control is hindered by limited understanding of the ecology of potential vector species.
METHODOLOGY/PRINCIPAL FINDINGS: We conducted a one year longitudinal study of P. knowlesi vectors in three sites within an endemic area of Sabah, Malaysia. All mosquitoes were captured using human landing catch. Anopheles mosquitoes were dissected to determine, oocyst, sporozoites and parous rate. Anopheles balabacensis is confirmed as the primary vector of. P. knowlesi (using nested PCR) in Sabah for the first time. Vector densities were significantly higher and more seasonally variable in the village than forest or small scale farming site. However An. balabacensis survival and P. knowlesi infection rates were highest in forest and small scale farm sites. Anopheles balabacensis mostly bites humans outdoors in the early evening between 1800 to 2000 hrs.
CONCLUSIONS/SIGNIFICANCE: This study indicates transmission is unlikely to be prevented by bednets. This combined with its high vectorial capacity poses a threat to malaria elimination programmes within the region.

Matched MeSH terms: Anopheles/parasitology
Efficacy of Clostridium bifermentans serovar Malaysia on target and nontarget organisms

Yiallouros M, Storch V, Thiery I, Becker N

J Am Mosq Control Assoc, 1994 Mar;10(1):51-5.
PMID: 7912261

Clostridium bifermentans serovar malaysia (C.b.m.) is highly toxic to mosquito larvae. In this study, the following aquatic nontarget invertebrates were treated with high C.b.m. concentrations (up to 1,600-fold the toxic concentration for Anopheles stephensi) to study their susceptibility towards the bacterial toxin: Planorbis planorbis (Pulmonata); Asellus aquaticus (Isopoda); Daphnia pulex (Cladocera); Cloeon dipterum (Ephemeroptera); Plea leachi (Heteroptera); and Eristalis sp., Chaoborus crystallinus, Chironomus thummi, and Psychoda alternata (Diptera). In addition, bioassays were performed with mosquito larvae (Aedes aegypti, Anopheles stephensi, and Culex pipiens). Psychoda alternata larvae were very susceptible, with LC50/LC90 values comparable to those of mosquito larvae (about 10(3)-10(5) spores/ml). The tests with Chaoborus crystallinus larvae showed significant mortality rates at high concentrations, but generally not before 4 or 5 days after treatment. The remaining nontarget organisms did not show any susceptibility. The investigation confirms the specificity of C.b.m. to nematocerous Diptera.

Matched MeSH terms: Anopheles/parasitology
Filaria vector competence of some Anopheles species

Zahedi M, White GB

Trop. Med. Parasitol., 1994 Mar;45(1):27-32.
PMID: 8066378

The filaria vector competence of Anopheles stephensi was compared with Brugia-susceptible Aedes aegypti Liverpool strain, An. gambiae Badagry Lagos strain and An. dirus Perlis Malaysia strain. An. stephensi ingested more Brugia pahangi microfilariae, had the highest infectivity rate and yielded more infective mosquitoes than the other two anopheline species. The overall vector competence of An. stephensi was 0.13 times that of Ae. aegypti, 0.62 times that of An. gambiae and 2.17 times that of An. dirus. However, heavy mortality among infected An. stephensi in the present investigation indicates that the filaria vectorial capacity of the mosquito might be limited epidemiologically. The relationship between filaria vector competence and mosquito foregut armature is discussed. It was observed that the relative vector competence of the three anopheline species tested was in the same order as their relative degrees of armature elaboration. The converse would be expected if foregut armatures really give partial protection to the mosquitoes against filarial infection. It is suggested that high host microfilariae density favours larval survival proportional to the degree of armature development in Anopheles (Cellia) species.

Matched MeSH terms: Anopheles/parasitology*
Quantitative trait loci in Anopheles gambiae controlling the encapsulation response against Plasmodium cynomolgi Ceylon

Zheng L, Wang S, Romans P, Zhao H, Luna C, Benedict MQ

BMC Genet, 2003 Oct 24;4:16.
PMID: 14577840

Anopheles gambiae females are the world's most successful vectors of human malaria. However, a fraction of these mosquitoes is refractory to Plasmodium development. L3-5, a laboratory selected refractory strain, encapsulates transforming ookinetes/early oocysts of a wide variety of Plasmodium species. Previous studies on these mosquitoes showed that one major (Pen1) and two minor (Pen2, Pen3) autosomal dominant quantitative trait loci (QTLs) control the melanotic encapsulation response against P. cynomolgi B, a simian malaria originating in Malaysia.

Matched MeSH terms: Anopheles/parasitology
[The first monkey malaria in Turkey: a case of Plasmodium knowlesi]

Özbilgin A, Çavuş İ, Yıldırım A, Gündüz C

Mikrobiyol Bul, 2016 Jul;50(3):484-90.
PMID: 27525405

Plasmodium knowlesi is now added to the known four Plasmodium species (P.vivax, P.falciparum, P.malariae, P.ovale) as a cause of malaria in humans because of the recent increasing rate of cases reported from countries of southeastern Asia. P.knowlesi which infects macaque monkeys (Macaca fascicularis and M.nemestrina) is transmitted to humans especially by Anopheles leucosphyrus and An.hackeri mosquitos. First human cases of P.knowlesi malaria have been detected in Malaysia which have reached high numbers in recent years and also have been reported from countries of Southeast Asia such as Thailand, Philippines, Myanmar, Singapore and Vietnam. However the number of cases reported from western countries are rare and limited only within voyagers. This report is the first presentation of an imported case of P.knowlesi malaria in Turkey and aims to draw attention to the point that it could also be detected in future. A 33-year-old male patient from Myanmar who has migrated to Turkey as a refugee, was admitted to a health center with the complaints of fever with a periodicity of 24 hours, headache, fatigue, cough, sore throat, anorexia, myalgia and arthralgia. He was prediagnosed as upper respiratory tract infection, however because of his periodical fever and background in Myanmar, thick and thin blood films were prepared and sent to our laboratory for further examinations. Microscopic examination of the thin blood films revealed erythrocytic stages compatible with P.knowlesi (three large early trophozoites in an erythrocyte, three late trophozoites with compact view, and three late band-form trophozoites). Upon this, both real-time polymerase chain reaction (Rt-PCR) targeting the small subunit ribosomal RNA (SSU-rRNA) genes of Plasmodium genus and DNA sequence analysis targeting P.knowlesi rRNA gene were performed. As a result, the suspected identification of P.knowlesi by microscopy was confirmed by Rt-PCR and DNA sequencing. The patient was treated with chloroquine and primaquine combination and in the follow-up on the seventh day after the treatment, his parasitemia and symptoms had ceased. Although there were some previous reports concerning about imported patients infected with different Plasmodium species in our country, no cases of P.knowlesi have been reported. This first case presented here emphasizes the occurence of P.knowlesi malaria in Turkey hereinafter due to the increasing number of refugees.

Matched MeSH terms: Anopheles/parasitology