At what temperature does Diphylobotrium latum die?

Diphyllobothrium latum Dies at Temperatures Above 56°C (133°F)

Diphyllobothrium latum (fish tapeworm) is effectively killed when heated to temperatures of at least 56°C (133°F) for a minimum of 5 minutes, or when frozen at -20°C (-4°F) or below for at least 48 hours. 1

Temperature Requirements for Inactivation

• Cooking fish to an internal temperature of at least 56°C (133°F) for 5 minutes will kill D. latum plerocercoids (infective larvae) 2, 3
• Freezing fish at -20°C (-4°F) or below for at least 48 hours is also effective in killing the parasite 1, 4
• Microwave cooking is not reliable for killing D. latum as it may not generate uniform temperatures throughout the fish 1

Transmission and Risk Factors

• D. latum infection (diphyllobothriasis) occurs primarily through consumption of raw or undercooked freshwater or anadromous fish containing plerocercoids 5, 6
• Common fish sources include:
  • Salmon 2
  • Perch 3
  • Trout 2
  • Mullet 2

Life Cycle Considerations

• D. latum requires two intermediate hosts (copepods and fish) before infecting humans 5
• The plerocercoids in fish muscle tissue are the infective stage for humans 5
• Plerocercoids must reach a certain maturity level in fish to be capable of infecting humans 5
• The parasite typically inhabits temperate and subarctic regions of the Eurasian continent but has been reported globally 5, 6

Prevention Strategies

• Cook all freshwater and anadromous fish thoroughly to at least 56°C (133°F) internal temperature 1, 4
• Alternatively, freeze fish at -20°C (-4°F) or below for at least 48 hours before consumption 1
• Avoid eating raw or undercooked fish, particularly in endemic areas 2, 6
• Be cautious with traditional dishes containing raw fish (sushi, ceviche, etc.) 4

Clinical Considerations

• Most infections present with mild gastrointestinal symptoms or are asymptomatic 2, 3
• Common symptoms include:
  • Abdominal pain 3, 6
  • Diarrhea 3
  • Spontaneous passage of proglottids (tapeworm segments) 2, 4
• Treatment typically involves a single dose of praziquantel (15 mg/kg) 2, 3

Important Caveats

• Chilling fish at 5°C for 5 days is NOT sufficient to kill D. latum plerocercoids 1
• Inadequate cooking methods (particularly microwave) may not achieve uniform temperatures needed to kill the parasite 1
• Traditional fish preparation methods like salting, smoking, or pickling may not reliably kill the parasite unless specific temperature thresholds are reached 4