Effect on the host

BLACK FLIES - EFFECT ON THE HOST

Direct Effect

  • Annoyance, painful bites resulting in severe reactions which may lead to death of an individual
  • Petechial haemorrhages especially on areas of fine skin, oedema of throat and abdomen is common
  • Flies enter the natural orifices especially the nose, eyes, ears and mouth of individuals
  • The flies attack in swarms and gadding is seen in animals
  • Milch cows are badly bitten and the teats are bloody and blocked or so sore that they do not tolerate milking, calves can not suckle
  • Repeated biting in man results in a syndrome called the black fly fever. This is characterised by headache, fever, sweating, shivering, nausea, swelling and tenderness of the lymphnodes, aching  joints, lassitude and psychological depression
  • Causative agents : S. venustum, S. erythrocephalum, S. posticalum.

Indirect Effect (vector potentiality)

  • Transmits Leucocytozoon smithi in turkeys and L. simondi in ducks
  • Intermediate host for Onchocerca gutturosa in cattle and O. volvulus of man which is very important since the filarid is the cause of river blindness in man
  • Mansonella ozzardi?
  • It also transmits eastern equine encephalitis virus and vesicular stomatitis virus in cattle
Last modified: Thursday, 24 June 2010, 5:20 AM