Microsoft word - material safety data sheet for necator americanus.doc

MSDS Necator americanus

NAME: Necator americanus infective larvae
SYNONYM: Human hookworm, necatoriasis
CHARACTERISTICS: Family Ancylostomatidae, subfamily Necatorinae; intestinal
nematode parasite, adult male measures 5-9 X 0.30 mm, female 9-11 X 0.35 mm; eggs
are 64-76 X 35-40 µm, infective larvae 630-670 X 20-30 µm.
PATHOGENICITY: Adults, eggs and rhabditiform larvae of N. americanus are not
infectious. Only third stage larvae (iL3) are infectious. Infective larvae can penetrate
intact skin and mucous membranes and can swim in water including a water film. They
will actively seek out a mammalian host, moving up a heat gradient. Once iL3 make
contact with the skin, they invade using mechanical and enzymatic mechanisms. iL3
penetrate initially under skin scales and down hair follicles. When iL3 penetrate, a pin-
point itching sensation is felt. The penetration site is marked by a small red spot within
several hours that progresses to a red papule and fades within a week.
Infective larvae penetrate the skin, enter into capillaries and undergo a blood-lung
migration that involves travel through the right side of the heart to the pulmonary
capillaries, escape into the alveoli, passage up the airways, travel down the oesophagus,
through the stomach to establish in the small intestine where maturity occurs. If both
sexes are present, mating occurs and eggs are produced in faeces usually within 8 weeks.
Hookworms suck blood and initiate an allergic response in the small intestine which
commences 3 weeks after penetration. Clinical signs occur at the penetration site (red
itchy papules) and during the intestinal establishment phase at 3-8 weeks (abdominal pain
and episodic diarrhoea). Passage through the lungs is usually asymptomatic and sub-
clinical. Heavy infections may cause anaemia in a person with iron deficiency, but
usually infections in people without iron deficiency are sub-clinical.
HOST RANGE: Humans. However, a strain of Necator americanus has been adapted to
hamsters in the laboratory.
INFECTIOUS DOSE: One iL3 is capable of penetrating intact skin, but at least one male
and one female are required for mating and to produce eggs in faeces.
MODE OF TRANSMISSION: Transmission is by penetration of iL3, typically through
intact skin, but also through mucous membranes.
COMMUNICABILITY: Not directly transmitted from person-to-person
MSDS Necator americanus
RESERVOIR: Humans, faeces, with 7 day old faecal cultures being highest risk. ZOONOSIS: None in nature although a laboratory strain of Necator americanus has been adapted to hamsters. VECTORS: None SECTION IV - VIABILITY DRUG SUSCEPTIBILITY: Adult hookworms can be treated with pyrantel, mebendazole, albendazole, levamisole, or nitazoxanide. Albendazole 400 mg orally can kill migrating juveniles of N. americanus and could be used in laboratory accidents. DRUG RESISTANCE: Strains with some resistance to mebendazole and pyrantel have been reported. SUSCEPTIBILITY OF iL3 TO DISINFECTANTS: Infective larvae can be killed within 10 minutes by 70% ethanol and within 15 minutes by 0.5% Dettol. PHYSICAL INACTIVATION: Infective larvae can be killed immediately by addition of hot water at near boiling point. Infective larvae also die when the water film they are in disappears due to evaporation. SURVIVAL OUTSIDE HOST: Infective larvae can survive up to 6 weeks in moist materials at ambient temperatures of 24-30°C. SECTION V - MEDICAL SURVEILLANCE: Occurrence of typical papules at penetration site is good evidence of penetration. Monitor for gut symptoms, particularly abdominal pain commencing 3 weeks after infection. If worms of both sexes are present, diagnosis can be confirmed by detection of eggs in faeces 8 weeks after infection. FIRST AID/TREATMENT: Wash site of contact with 70% ethanol or Dettol. If these chemicals are not quickly available, wash the site immediately with running water and dry the skin to remove all water film. If lesions typical of penetration develop at site within 24 hours, consider treatment with albendazole to kill migrating larvae. Adult and juvenile hookworms in the intestine can be treated with anthelmintic drugs listed above. IMMUNIZATION: None available CHEMOPROPHYLAXIS: None available SECTION VI - LABORATORY HAZARDS MSDS Necator americanus
LABORATORY-ACQUIRED INFECTIONS: None reported to date. SOURCES/SPECIMENS: High risk specimens are faecal cultures aged 7 days which contain iL3. This would rarely occur in routine aerobic faecal bacterial plates since they are usually disposed of prior to 7 days. High risk with hookworm or Strongyloides cultures, particularly agar plate and Harada-Mori cultures. PRIMARY HAZARDS: Water drops or films containing iL3 coming into contact with skin or mucous membranes. SPECIAL HAZARDS: None SECTION VII - RECOMMENDED PRECAUTIONS CONTAINMENT REQUIREMENTS: Biosafety level 2 practices and containment equipment for all activities involving iL3. PROTECTIVE CLOTHING: Laboratory coat; gloves should be worm at all times when working with live iL3. OTHER PRECAUTIONS: Cultures of iL3 should be covered whenever they are not being accessed by researchers and should be labeled as infectious. SECTION VIII - HANDLING INFORMATION SPILLS: Allow aerosols to settle. Avoid any contact between liquid and skin or clothing. Wear gloves, carefully apply five times the volume of 70% ethanol. Allow sufficient contact time (20 mins) before clean up. On heat resistant surfaces, another option is to flood with water at near boiling point, leave 5 mins and clean up. Dispose into a sealed container. DISPOSAL: When working with iL3, protect others against downstream risk. All iL3 should be killed prior to placing in general infectious waste. Infective larvae and material used (microscope slides, pipettes, test tubes, culture vessels) can be made risk free by placing in a larger container and flooding with 70% ethanol or 0.5% Dettol for 15 mins or water at near boiling point. Solid waste should be placed and sealed in airtight containers, and placed in infectious waste container. Disposal after this can be routine. STORAGE: In sealed containers that have an infection hazard label and specifically labeled as infective larvae of human hookworm. SECTION IX - MISCELLANEOUS INFORMATION Date prepared: June, 2007 MSDS Necator americanus
Prepared by: Rick Speare, Wayne Melrose, School of Public Health, Tropical Medicine and Rehabilitation Sciences, James Cook University, Townsville 4811 and John Croese and Sharon Cooke of Gastroenterology Department, The Townsville General Hospital, Douglas, Townsville 4814, Australia. Based on an MSDS from Health Canada (2001).


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