BRIEF INFORMATION ON ON-GOING STUDIES
Molecular approaches for blood meal identification
The objective of this study is to establish a Polymerase Chain Reaction (PCR) technique based on cytochrome b (cytb) gene of mitochondria DNA (mtDNA) for blood meal identification. The PCR technique was established and validated using blood samples of wild and laboratory animals. The primers used are complementary to the conserved region of the cytb gene of vertebrate mtDNA. Blood samples were analyzed and the PCR products were sequenced. The obtained sequences were compared with those in GenBank database using BLAST program to identify the vertebrate animal species. This use of this molecular technique for identification of blood meals in haematophagous arthropods especially in ticks will be investigated.
Repellency of crude plant extacts against chiggers
This study is undertaken to examine the repellency of crude plant extracts of onion (Allium cepa var. aggregatum), garlic (Allium sativum), clove (Syzygium aromaticum), Cinnamon (Cinnamomum zeylanicum), ginger (Zingiber officinale) and pandanus (Pandanus amaryllifolious) against larval Leptotrombidium deliense, a vector of scrub typhus. Larvae used in the study are obtained from laboratory colonies maintained at Acarology Unit, Institute for Medical Research. Commercial cotton buds with plastic shafts are used to hold the test repellent. Extracts of different concentrations (10%, 5%, 2.5%, 1%, 0.1%, and 0.01%) are evaluated. Test repellent is dropped on each cotton bud. A chigger is next placed at the bottom of the treated cotton bud. Chiggers that climbed up to the top of treated cotton buds are considered as not repelled by the test repellent and those that did not are considered repelled.
Detection and identification of acari found on animal carcasses
The purpose of this study is to detect and identify acari associated with carcasses, the surrounding soil and on insects. Three different sizes of animal carcasses are used (rats, rabbits and monkeys). Screening and collecting for acari are done daily for 35 days. All acari excluding ticks, are collected, kept in a preservative and identified.
Detection and identification of pathogens in ticks
This is a 2-year project funded by a MOH Grant that started in August 2011 and shall end in July 2013. DNA of identified live ticks with known animal host and location of collection (forests, coastal areas, commercial cattle farm, animal resource centre & Point of Entry) in Selangor are screened using Polymerase Chain Reaction (PCR) and a commercial assay for the presence of Rickettsia and Borrelia. All positive results are sequenced to verify the obtained results and to classify the detected Rickettsia or Borrelia species. In another experiment, two different regions of mtDNA cyt b gene are amplified for host blood meal identification of the engorged ticks. PCR products of the positive results are sequenced to obtain species-specific restriction sites for the diagnosis of the host (human / animal) blood meals. A list of potential species of ticks as vectors of Rickettsia and Borrelia, the origin location and their host/s shall be compiled.
Detection of rickettsioses of public health importance in ticks using polymerase chain reaction (PCR) assays.
This is a 3-year project funded by a MOH Grant that started in August 2008 and ended in July 2011. DNA of ticks of various hosts is screened using Polymerase Chain Reaction (PCR) for the presence of rickettsial agents. These ticks were collected from previous fieldworks conducted (2003-2007) in 24 locations of different ecology in Peninsular Malaysia. Seven extensive follow-up fieldworks were then carried out to collect fresh ticks from areas with high infectivity of rickettsial diseases determined from previous studies. Trapping of host and examination of vegetation were conducted in different ecological areas within the study sites. Host was identified and anaesthetized for extraction of ticks. Where allowed, hosts were sacrificed for their blood and tissues (spleen and liver). Ticks were identified to document the species prior to extraction of their DNA. A total of 770 DNA of fresh ticks, 78 blood samples and 127 tissues of animals were then examined for the presence of rickettsial agents using PCR.
Establishment of pure line of Suidasia pontifica colony in laboratory (2010 – 2012)
This study is to establish a pure line of Suidasia pontifica colony in laboratory. Adult female mites are kept individually in separate glass vials. A sheet of cigarette paper is secured in place with parafilm over the mouth of each vial. Approximately 1 mg of food is introduced into each vial. All the vials are kept in a storage box containing a saturated sodium chloride solution. The storage box is kept in an air-conditioned room at 25°C. The mites are observed twice daily until they died. Dead mites are then mounted and their identity confirmed. Eggs which are oviposited are monitored and maintained until adulthood. Those adult mites are then pooled together to form a colony.
Horizontal spatial distribution of dust mites in mattresses (2011 – 2013)
This study is conducted to evaluate and compare the distribution of house dust mites on four quadrates of mattresses. Each mattress is divided lengthwise into 4 horizontal equal parts. Each part is vacuumed separately for 1 minutes by vacuum cleaner and dust is collected over a Whatman no. 1 filter paper. The day temperature, relative humidity (RH) and information of selected mattresses in each room are recorded simultaneously. The dust is weighed and processed in a sieve shaker. The processed fine dust is suspended in 90% lactic acid and is examined under 20x magnification. Whole mites and mite fragments are picked and mounted in Hoyer's medium. Mounted slides are dried in an oven before the mites are identified and counted.
LIST OF STUDIES CONDUCTED IN THE LAST 5 YEARS (year start – year complete)
- Detection and identification of acari found on animal carcasses (2011-2013)
- Detection and identification of pathogens in ticks (2011-2013)
- Acarine ectoparasites of pet Burmese python, Python molurus bivittatus in Malaysia (2010-2010)
- Repellency of crude plant extracts against chiggers (2009-2011)
- Molecular approaches for blood meal identification (2009-2013)
- Movements and home range of tree-shrews, Tupaia glis surrounding houses of otoacariasis cases in Kuantan, Pahang (2009-2010).
- Detection of rickettsioses of public health importance in ticks using polymerase chain reaction (PCR) assay (2009-continuing).
- Rapid detection of Orientia tsutsugamushi in chiggers using polymerase chain reaction assay (2009-2010).
- A preliminary checklist of acarine ectoparasites in Bukit Panchor and Pulau Jerejak, Penang (2008-2008).
- A preliminary checklist of acarine ectoparasites in Pangkor Island (2008-2008).
- Scanning electron micrographs of house dust mites, Austroglycyphagus malaysiensis and Suidasia pontifica (2008-2008).
- A preliminary checklist of acarine ectoparasites in Cameron Highlands (2007-2007)
- Scanning electron micrographs of Tyrophagus putrescentiae, a common dust mite in Malaysia (2007-2007)
- Effects of microwave radiation on house dust mites (Dermatophagoides pteronyssinus and Dermatophagoides farinae) (2007-2009)
- Laboratory bioassay of 4 commercial repellents against Leptotrombidium deliense (2007-2008)
- Ecology of human otoacariasis in the state of Pahang (2006-2008)
- Species distribution of ticks on small animals in human settlements in urban and rural areas of Peninsular Malaysia (2006-2009)
- Toxicities of lemon grass (Cymbopogan nardus) and Neem (Azadirachta indica) to dust mites (2006-2007)
- Establishment of new chigger colonies in the laboratory (2006-2008)
- Residual activity of crude plant extracts on house dust mites (2006-2007)
- Evaluation of effectiveness of two commercial disinfectants and vaporizing mosquito mats against house dust mites (2006-2010)
- Effects of a commercial ionizer on house dust mites Dermatophagoides pteronyssinus and Dermatophagoides farinae (2006-2009)
- Residual activity of benzyl benzoate against Dermatophagoides pteronyssinus (Acari: Pyroglyphidae) (2006-2008)
Diploma of Applied Parasitology & Entomology (DAP&E) Course – Acarology Module
The DAP&E course is a 5-months course held in the Institute for Medical Research. The Acarology module is conducted in about 2 weeks and includes lectures, practicals and field trips. The lectures cover basic taxonomy, biology, ecology, distribution of acari of public health importance. In the practical sessions, participants are taught to identify common Malaysian acari of public health importance, and on basic laboratory and field techniques. In the field trips, participants are able to practice various techniques of collecting acari from the environment and from hosts. The programme for the module is listed below. Interest individuals can apply to attend only the Acarology. module.
- Introduction to Acarology (Lecture, 1 hr)
- Field techniques in Acarology (Lecture, 1 hr)
- Laboratory techniques in Acarology (Lecture , 1 hr)
- Rearing techniques in Acarology (Lecture, 1 hr)
- Metastigmata: General (Lecture, 1 hr)
- Mesostigmata: General (Lecture, 1 hr)
- Prostigmata: General (Lecture, 1 hr)
- Astigmata: General (Lecture, 1 hr)
- Vectors of Scrub Typhus (Lecture, 1 hr)
- House dust mites (Lecture, 1 hr)
- Scabies (Lecture, 1 hr)
- Identification: Metastigmata (Practical, 2 hr)
- Identification: Mesostigmata (Practical, 2 hr)
- Identification of chiggers (Practical, 2 hr)
- Identification of house dust mites (Practical, 2 hr)
- Mounting: Mesostigmata (Practical, 2 hr)
- Mounting of chiggers (Pratical, 2 hr)
- Mounting of house dust mites (Practical, 2 hr)
- Field trip (10 hr)
- Processing animals for ectoparasites (Practical, 2 hr)
Ad hoc training
The Unit regularly conducts ad hoc short term training in various aspects of Acarology as requested by external individuals and institutions. The duration of this type of training depends on the subject matter and needs of the clients. Such training does not usually exceed more than a month. The training programme may be tailor-made to suit the needs of the client. Clients can opt to enroll in the Acarology module of the Diploma of Applied Parasitology and Entomology course mentioned above. Clients may be charged a fee to cover traiing costs. Please contact the Head of Acarology Unit for more information.
Many undergraduates from local universities have undergone their industrial training with the Unit. Duration of such training is usually between 1-3 months and varies according to needs of the Universities and the agreement of our Unit. Trainees on short attachments will be introduced to and will have a hands-on experience in the various activities undertaken by the Unit. Trainees on long attachments may be assigned a short research project to undertake on their own under the supervision of officers of the Unit. Request for industrial training should be addressed to the Director of the Institute for Medical Research. Please contact the Head of Acarology Unit for more information.
Undergraduate and Postgraduate Supervision or Consultancy
Senior researchers in the Unit regularly serve as external supervisors or consultants in undergraduate and postgraduate research projects that involves various aspects of Acarology. We provide training in laboratory and field techniques, advice on study design, mentoring, research guidance, data analysis, thesis writing and publication of findings. Please contact the Head of Acarology Unit or our research officers for further discussions.