1. General Procedure For Submission Of Specimen

Acarines (ticks and mites) which are suspected to be causative agents or vectors of human diseases, may be submitted to the Acarology Unit of IDRC, for identification. Every specimen must be labelled clearly and accompanied by a pathological examination request form. The form must be completed with the following information: brief case history of patient (for clinical specimens), description or identification of non-host(if any), description of habitat, locality where specimen is collected, date and time of collection, name and address of collector, and date specimen sent to the IMR.

The success of identification depends on the condition of the specimen sent. To ensure success and also to reduce exposure to hazards for the staff performing the identification, all specimens must be prepared carefully following the instructions below before despatching to the IMR.

Generally all mites and ticks can be sent live or preserved in 70% alcohol. It is preferred that specimens be sent in 70% alcohol. If live specimens are sent, the container must be clearly labelled “HAZARDOUS – LIVE SPECIMENS”. When live ticks, place the ticks inside a sealed container with a piece of damp filter paper inside to increase the humidity and prevent the specimen from dehydrating.

It is not advisable to send mounted mites. Mounting of mites is a precise process and experience is required. If not done properly, it may damage the specimen making identification difficult or impossible. Although it is possible to remount specimens, some damage may occur too during remounting. The IMR will undertake the mounting of the specimens.

2. Specimen Collection And Preparation

2.1. Acarines specimens from humans

i. Sarcoptes scabiei (Scabies mite)

The mite can usually be found in the stratum corneum of the following areas: the clefts between the fingers and toes, flexor surface of the wrist, extensor surface of the elbow, the axilla, penis, scrotum, and under the breast.

Skin scrapping is generally not suitable for the collection of scabies mites. The mites can be damaged by the procedure and the relatively large mass of skin cell debris makes it difficult to find the mites. Besides that, intact mites are required for accurate identification. If skin scrapings are submitted, the specimens must be sent in 70% alcohol. DO NOT SUBMIT THE SKIN SCRAPPINGS IN ITS ORIGINAL FORM as it may be hazardous to the person processing the specimen.

The recommended technique to collect scabies mites is first to locate the burrows made by the mites in the skin of the clefts between the fingers and the wrists of patients. Once located, a sharp sterile needle or lancet is used to slowly tease open the burrow until a small white object, which is the scabies mite, is observed. The mites can be picked up using the moistened sharpened end of an application stick and sent in 70% alcohol.

ii. Ticks in the ear canal

Ticks have been observed in the ear canal of patients. The ticks may cause facial paralysis unless removed. Ticks attached inside the ear canal can be removed by instilling warm water, mineral oil or 4% lignocaine. The solutions shall induce the ticks to detach; these ticks can then be removed using forceps, placed in 70% alcohol and sent to the IMR.

iii. Other ectoparasitic acarines

This will require detailed examination of the whole body of the patient. A hand lens will assist in locating these acarines. Use fine forceps to grip larger mites as near to the skin as possible and pull gently away. Smaller mites should be teased from the skin using a sharp sterile needle or lancet.

Ectoparasitic ticks on humans are also removed by using sharp pointed forceps. Grip the tick on the gnathosome (head) as close as possible to the skin of the patient. Pull away gently from the skin. Care must be taken not to separate the head of the tick from the rest of the body. The tick must be intact for accurate identification.

iv. Other endoparasitic acarines

These are usually found in dissected or autopsy tissues. The tissues are examined under a dissecting microscope and the mites removed using needles and scissors. Specimens are put in 70% alcohol and send to the IMR. If facilities and experience is not available for the removal of endoparasitic mites, then the tissues may be put in 70% alcohol and send to the IMR.

2.2. Acarine specimens from animals

i. Ectoparasitic acarines

Live animal hosts must be anaesthetised before extraction of ectoparasites. The following process is to be used for small animals such as rodents. Place each small animal in a cloth bag. Put the animal and cloth bag in a glass jar with a cotton wad soaked with chloroform. After 5 minutes, or longer for larger mammals, the cloth bag containing the animal is taken out off the glass jar. The animal is next removed from the cloth bag. The cloth bag is turned inside out and shaken over a white enamel tray. The bag and tray is carefully examined for detached ectoparasitic acarines. These acarines can be picked up using the moistened sharpened end of an applicator stick. The acarines are put in 70% alcohol and send to the IMR.

The animal is then placed on a white enamel tray and brushed with a fine-tooth comb. This will dislodge most mites and ticks. Check for these acarines in the enamel tray. The acarines can be picked up with the moistened sharpened end of an applicator stick. The acarines are put in 70% alcohol and send to the IMR.

Animals should be examined too for acarines which are not dislodged by combing. Where possible, examine the animal under a dissecting microscope. Use a pointed forceps to grip the gnathosome (head) of any tick present, as close as possible to the skin of the host. Pull away gently from the skin. A sharp needle may be used to tease the skin around the attached ticks to assist in its removal. Care must be taken not to separate the head of the tick from the rest of the body. The tick must be intact for accurate identification. Place the acarines in 70% alcohol and sent to the IMR.

ii. Endoparasitic acarines

Internal organs and tissue of animals suspected to contain endoparasitic acarines should be removed and placed in 70% alcohol and sent to the IMR.

2.3 Specimens from the environment

i. Ectoparasitic acarines on vegetation

Many unfed ectoparasitic acarines, especially ticks, climb onto surrounding vegetation such as tall grasses, leaves of small plants, shrubs, etc., to wait for a host to pass by. The vegetation and underside of leaves can be examined. Moisten the sharpened end of an applicator stick or a fine brush, to pick up any acarines found. Send the acarines in 70% alcohol to the IMR.

A procedure known as ‘flagging’ is an effective way to collect acarines especially ticks from vegetation. A white flannel cloth is tied to a stout stick and used to brush/sweep the vegetation. Ectoparasitic acarines detach from the vegetation and attach to the moving cloth. The cloth is examined and any acarines found can be removed using the above stated procedure.

Black formica or plastic rectangular plates (usually 10 x 13 cm) can be placed beneath vegetation or inside ground burrows or holes to collect chiggers. After about 5 minutes, the plates are examined and any acarines found can be removed using the above stated procedure.

Leaf litter, animal nests or soil suspected to harbour acarines can be collected into plastic bags. A few pieces of damp filter paper or tissue paper are put in the bags to keep the contents moist. The bags are heat sealed and sent as soon as possible to the IMR.

ii. Acarines in houses

Occasionally acarines can be seen inside houses. Moisten the sharpened end of an applicator stick or a fine brush, to pick up any acarines found. Put the acarines in 70% alcohol and send to the IMR.

Rodent and bird nests in houses (usually in the attic or roof) may harbour mites that can bite man. These nests can be collected into plastic bags. A few pieces of damp filter paper or tissue paper are put in the bags to keep the contents moist. The bags are heat sealed and sent as soon as possible to the IMR.

Dust that suspected to contain acarines is collected using a vacuum cleaner. Use a new vacuum bag for each sample. Place each vacuum bag in a plastic bag. Heat seal the plastic bag and send immediately to the IMR. Store the plastic bags in the lower compartment of a refrigerator if the bags could not be send to the IMR on the day the specimen is collected.