Infectious Disease Index

Onchocerca volvulus

MATERIAL SAFETY DATA SHEET - INFECTIOUS SUBSTANCES

SECTION I - INFECTIOUS AGENT

NAME: Onchocerca volvulus

SYNONYM OR CROSS REFERENCE: Onchocerciasis, river blindness, blinding filarial disease, enfermedad de roblex, erisipela de la coste, mal morado, craw-craw, gale filarienne, ceguera de la rios

CHARACTERISTICS: Filarial nematode, helminth, female worms are 23-50 cm long and 250-450 µm wide, male worms are 16-42 cm long and 150-200 µm wide; microfilariae vary from 220-360 µm, unsheathed and contains a cephalic space; long-lived (8-15 years);

SECTION II - HEALTH HAZARD

PATHOGENICITY: Heavy infection can lead to 3 main clinical manifestations including dermatitis, eye lesions, and subcutaneous nodules; initially, changes in skin pigmentation are observed, followed by loss of skin elasticity; subcutaneous nodules contains adult worms and are usually firm, varies in size and location; complications are corneal opacities and blindness; chronic and nonfatal; embryonic stage of the organism causes most of the pathology; female worm discharges microfilariae that migrate through the skin; microfilariae can be found in tissues other than the skin and eye; refinfection may occur, severity is dependent on the cumulative effects of repeated infections

EPIDEMIOLOGY: Universal susceptibility, endemic in 37 countries; prevalent in West Africa, widespread Guatemala and Mexico; foci in South and Central America including Venezuela, Colombia, Surinam, Brazil and Ecuador

HOST RANGE: Humans; experimental transmission to chimpanzees, gorillas; other Onchocerca species found in animals cannot infect humans but may occur together with O. volvulus in the insect vector

INFECTIOUS DOSE: Not known

MODE OF TRANSMISSION: By the bite of an infected female blackfly (Simulium spp.)

INCUBATION PERIOD: Variable; microfilariae found in the skin 1 year or more after infective bite; in Guatemala, found in children by 6 months of age; in Africa, vector can be infectious 7 days after a blood meal

SECTION III - DISSEMINATION

RESERVOIR: Humans

ZOONOSIS: None, but blackfly is crucial biological reservoir as well as vector

VECTORS: Blackfly (Simulium spp.) which breed rapidly in flowing rivers and streams

SECTION IV - VIABILITY

DRUG SUSCEPTIBILITY: Sensitive to diethylcarbamazine citrate, suramin, ivermectin; ivermectin not effective in killing adult worms (macrofilariae)

SUSCEPTIBILITY TO DISINFECTANTS: Infective stages sensitive to 1% sodium hypochlorite

PHYSICAL INACTIVATION: Infective stages sensitive to heating at 56° C for 30 minutes

SURVIVAL OUTSIDE HOST: Infective stages sensitive to freezing

SECTION V - MEDICAL

SURVEILLANCE: Monitor for symptoms; confirm by microscopic demonstration of microfilariae in tissue biopsy; evidence of microfilariae in urine or by excising nodules and confirming presence of adult worms

FIRST AID/TREATMENT: Administer appropriate drug therapy

IMMUNIZATION: None available

PROPHYLAXIS: None available

SECTION VI - LABORATORY HAZARDS

LABORATORY-ACQUIRED INFECTIONS: None reported to date

SOURCES/SPECIMENS: Skin biopsy specimens, nodules, blood, tears, sputum and urine

PRIMARY HAZARDS: Accidental parenteral inoculation; droplet exposure of the mucous membranes

SPECIAL HAZARDS: None

SECTION VII - RECOMMENDED PRECAUTIONS

CONTAINMENT REQUIREMENTS: Biosafety level 2 practices and containment equipment for all activities involving infective stages of the parasite and potentially infectious body fluids or tissues

PROTECTIVE CLOTHING: Laboratory coat; gloves when skin contact with infectious materials is unavoidable

OTHER PRECAUTIONS: None

SECTION VIII - HANDLING INFORMATION

SPILLS: Allow aerosols to settle; wearing protective clothing, gently cover the spill with absorbent paper towel and apply 1% sodium hypochlorite, starting at the perimeter and working towards the center; allow sufficient contact time (30 mins) before clean up

DISPOSAL: Decontaminate all wastes before disposal; steam sterilization, chemical disinfection, incineration

STORAGE: In sealed containers that are appropriately labelled

SECTION IX - MISCELLANEOUS INFORMATION

Date prepared: March, 2001

Prepared by: Office of Laboratory Security, PHAC

Although the information, opinions and recommendations contained in this Material Safety Data Sheet are compiled from sources believed to be reliable, we accept no responsibility for the accuracy, sufficiency, or reliability or for any loss or injury resulting from the use of the information. Newly discovered hazards are frequent and this information may not be completely up to date.

Copyright © Health Canada, 2001