Mansonella

• Mansonella spp.


  Species of parasitic nematode worms

  
• Mansonella species

  • Mansonella ozzardi
  • Mansonella perstans
  • Mansonella streptocerca
• Vectors

  • Culicoides midge
  • Simulium blackfly
• Vectors and Mansonella species

  Culicoides midge transmits M. ozzardi, M. perstans, M. streptocerca

  Simulium blackfly transmits M. ozzardi

  
• Epidemiology of Mansonella species

  • Mansonella perstans endemic in west, east, and central Africa, and Central and South America

  Mansonella streptocerca old world species in west and central Africa

  Mansonella ozzardi new world species in central and south America, Caribbean Islands

  
• Adult M. perstans

  Male: 45 mm by 60 um

  Female: 70 - 80 mm by 120 um
• Microfilaria of M. perstans

  Unsheathed

  Nuclei extending to the tip of the tail
• Adult M. ozzardi

  Male: 26 mm by 70 um

  Female: 49 mm by 150 um
• Microfilaria of M. ozzardi

  Unsheathed

  No nuclei at the tip of the tail

  
• Adult M. streptocerca

  Male: 50 um

  Female: 27 mm by 50 um
• Microfilaria of M. streptocerca

  Unsheathed

  Nuclei extend to the tip of the hooked tail
• Life cycle of M. perstans

  Infective stage for humans is L3

  Vector bites human host, larvae migrate cavities and mature into adults

  Adults copulate and female produces microfilariae

  Microfilariae infect Culicoides midge, develop to L3, which infect human host

  
• Life cycle of M. ozzardi

  L3 introduced to human host, mature in subcutaneous tissue

  Adults copulate and produce microfilariae in bloodstream

  Microfilariae infect vector (Culicoides midge or Simulium blackfly), develop to L3, which infect human host

  
• Life cycle of M. streptocerca

  Vector bites human, L3 matures in dermis

  Adults copulate and produce microfilariae in blood

  Microfilariae infect vector, develop to L3, which infect human host

  
• Pathogenesis and Clinical Manifestations

  • Generally mild presentation

  Many asymptomatic, especially in endemic regions

  Possible co-infections with other filarial diseases
• Symptoms of M. perstans infection

  Commonly asymptomatic

  If symptomatic, related to migrating adult worms: pericarditis, pleuritis, angioedema, pruritus, fever, headache, arthralgia, fatigue, neuropsychiatric manifestations

  
• Symptoms of M. ozzardi infection

  Majority asymptomatic

  If symptomatic: fever, pruritus, arthralgia, headache, rashes, lymphadenopathy, edema, pulmonary symptoms, eosinophilia, corneal lesions (keratitis)
• Symptoms of M. streptocerca infection

  Most asymptomatic

  If symptomatic: pruritus, dermatitis, hyperpigmented lesions, papular eruptions, eosinophilia
• Diagnostic methods

  • Microfilaria in bloodstream (M. ozzardi, M. perstans)

  Microfilaria in skin snips (M. streptocerca)

  Adult worms in their habitat

  Molecular detection (RT-PCR, LAMP)

  Serologic testing (limited due to cross-reactions)

  
• Habitat of adult worms

  M. perstans: peritoneal, pleural, pericardial cavities

  M. ozzardi: subcutaneous tissue

  M. streptocerca: dermis less than 1 mm from skin

  
• Treatment

  No optimal treatment

  Ivermectin

  Diethylcarbamazine plus mebendazole
• Prevention and Control

  • Insect repellant

  Wearing clothes that cover most of the skin