RIVER BLINDNESS (An Overview)

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RIVER BLINDNESS(An Overview)

• CHINEDU UMEADI (Ph.D. Student)
• Walden University
• PUBH-8165-1
• Instructor Dr Stephen Arnold
• Spring Quarter, 2011
• --------------------------------------------------
  ----------------
• Adult black fly feeding on skin. Retrieved from,
  http//www.canadatrip.co.uk
• Adult man suffering with river blindness.
  Retrieved from, http//www.goldbamboo.com/pictures
  -t2344.html

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Presentation Contents

• Introduction
• Black fly (Similium species)
• Life cycle of Onchocerca volvulus
• Eye lesion
• Spread of river blindness
• People at risk for river blindness
• Epidemiology
• Public health burden
• Diagnosis
• Prevention Treatment
• Questions and Discussions

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Expected Learning Outcomes

• Meaning of river blindness
• Cause and pattern of spread of river blindness
• Extent of the problem
• Prevention and management of river blindness

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Introduction

• A parasitic disease
• Caused by Onchocerca volvulus
• Characterized by skin changes, subcutaneous
  nodules, ocular lesions, lymphatic pathology and
  some systemic effects
• Transmitted by blackflies of the Similium species
• Almost exclusively a parasite that infects man
• Picture of Onchocerca volvulus. Retrieved from,
  http//bio390parasitology.blogspot.com/2011/02/onc
  hocerca-volvulus-another-price-of.html
• World Health Organization. (2011). Prevention of
  blindness and visual impairment. Priority eye
  disease Onchocerciasis (river blindness).
  Retrieved July 19, 2011, from http//www.who.int/b
  lindness/causes/priority/en/index3.htmt.

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Black Fly (Similium species)

• Different species of Similium
• Similium damnosum
• Similium neavei
• Similium ochraceum
• Similium metallicum
• Similium callidium
• Similium species breed in fast-flowing streams
  and rivers
• They only feed in the day and this corresponds to
  the time that the microfilaria migrate to the
  skin
• Adult black fly feeding on skin. Retrieved from,
  http//www.canadatrip.co.uk
• Young girl playing near a fast flowing water.
  Retrieved from, http//img.ehowcdn.co.uk/article-p
  age-main/ehow/images/a07/sa/tv/rid-biting-black-fl
  ies-800x800.jpgimgrefurl

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Lifecycle of Onchocerca volvulus

• Similium fly ingest microfilariae during feeds
• Microfilariae undergoes development in the fly
• Development in the fly takes about 15 days
• Larval forms are transmitted to humans during
  feeds
• Lucas, A., Gills, H. (1990). A new short
  textbook of preventive medicine for the tropics.
  (3rd ed.). Kent, UK Edward Arnold.

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Lifecycle of Onchocerca volvulus Contd...

• The larva migrates to the subcutaneous tissue of
  the new host
• They mature into adult worms over six to twelve
  months
• Mature adult worms mate in the subcutaneous
  tissue producing microfilaria
• Microfilaria migrate to the skin where they are
  fed on by the Similium flies
• The cycle then starts again
• Lucas, A., Gills, H. (1990). A new short
  textbook of preventive medicine for the tropics.
  (3rd ed.). Kent, UK Edward Arnold.

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Lifecycle of Onchocerca volvulus Contd...

• Life Cycle of Onchocerca volvulus. Retrieved
  from, http//www.cdc.gov/parasites/onchocerciasis/
  biology.html

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Eye lesions

• Caused in humans by microfilariae which can be
  found in all internal tissues of the eye except
  the lens
• They cause the following types of lesions
• Fluffy corneal opacities
• Sclerosing keratitis
• Anterior uveitis with or without secondary
  glaucoma
• Choroidoido-retinitis
• Optic neuritis and postneuritic optic atrophy
• Endosybiont called Wolbachi pipientis are
  released when the worms die
• This triggers some immune response which can lead
  to blindness
• Elderly man blinded by onchocerciasis. Retrieved
  from, http//apps.who.int/tdr/svc/diseases/onchoce
  rciasis
• Retina in Onchocerciasis. Retrieved from,
  http//www.sciencephoto.com/media/260256/enlarge

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Spread of river blindness

• Spreads from person to person by bite of
  blackfly
• Exposing the body increases the chance of
  infection
• The more the bites, the more the infection
• Blindness occurs with longstanding and intense
  infection
• African fisherman. Retrieved from,
  http//www.un.org/ecosocdev/geninfo/afrec/vol20no1
  /201-fishing-revolution.html
• African men near a river. Retrieved from,
  http//www.superstock.co.uk/stock-photos-images/40
  22-20850
• Holiday makers. Retrieved from,
  http//www.crete-connections.com/Crete-Accommodati
  on.htm
• Centers for Disease Control and Prevention.
  (2011). Fact sheet for general public health
  River blindness (Onchocerciasis). Retrieved July
  19, 2011, from http//www.wellnessproposals.com/he
  alth-care/handouts/parasitic-zoonotic-diseases/onc
  hocerciasis-factsheet.pdf

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People at risk for river blindness

• People living around fast flowing streams
• Adventure travellers
• Missionaries
• Peace Corp Volunteers
• People exposed to blackfly bites for long periods
• Adventure traveller. Retrieved from,
  http//ericasavage.blogspot.com/2010_06_01_archive
  .html
• People living near water fast flowing stream.
  Retrieved from http//goafrica.about.com/od/africa
  traveltips/tp/bestwestafrica.htm
• Volunteers teaching. Retrieved from,
  http//www.advance-africa.com/
• Centers for Disease Control and Prevention.
  (2011). Fact sheet for general public health
  River blindness (Onchocerciasis). Retrieved July
  19, 2011, from http//www.wellnessproposals.com/he
  alth-care/handouts/parasitic-zoonotic-diseases/onc
  hocerciasis-factsheet.pdf

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Epidemiology

• Some 37 million people are infected worldwide
• Some 90 million people are at risk of infection
  based on their areas of residence
• About 270,000 people are blind as a result of the
  infection
• About 500,000 people have visual impairment as a
  result of the infection
• Nearly 99 of infected people live in Africa
• Second leading infectious cause of blindness in
  the world
• The remainder live in Yemen, and six countries in
  the Americas
• Centers for Disease Control and Prevention.
  (2011). Fact sheet for general public health
  River blindness (Onchocerciasis). Retrieved July
  19, 2011, from http//www.wellnessproposals.com/he
  alth-care/handouts/parasitic-zoonotic-diseases/onc
  hocerciasis-factsheet.pdf

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Public health burden of river blindness

• Global burden of 987, 000 DALYS
• Severe pruritis is responsible for 60 of the
  DALYS
• About half of middle aged men in West Africa have
  been blinded by the illness
• Brings about economic loss
• Annual economic losses were estimated in 1970s to
  be US 30, 000,000
• World Health Organization. (2011). Prevention of
  blindness and visual impairment. Retrieved from,
  http//www.who.int/blindness/partnerships/onchocer
  ciasis_disease_information/en/index.html

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Diagnosis

• Skin snip
• Surgical removal and examination of nodules
• Slit-lamp examination of the anterior part of the
  eye
• Antibody tests
• Demonstration of skin snip. Retrieved from
  http//www.stanford.edu/class/humbio103/ParaSites2
  006/Onchocerciasis/Diagnosis.html
• Laboratory scientist at work. Retrieved from,
  http//www.fmcowerri.com/departments-and-units/mic
  robiology/
• Centers for Disease Control and Prevention.
  (2011). Parasites Onchocerciasis Diagnosis.
  Retrieved August 8, 2011, from http//www.cdc.gov/
  parasites/onchocerciasis/diagnosis.html

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Prevention and treatment

• No vaccines available
• Personal protection measures against biting
  insects
• Ivermectin is used to kill the larvae in the body
  (CDC, 2011)
• Promising treatments such as doxycycline which
  will kill the adult worms are being studied (CDC,
  2011)
• Mass distribution of Ivermectin to everyone
  living in areas where Onchocerca volvulus is
  found has been shown to be effective (WHO, 2011)
• World Health Organization. (2011). Onchocerciasis
  disease information Prevention of Blindness and
  visual impairment. Retrieved July 18, 2011
  fromhttp//www.who.int/blindness/partnerships/onch
  ocerciasis_disease_information/en/index.html
• Centers for Disease Control and Prevention.
  (2011). Onchocerciasis Prevention and Control.
  Retrieved July 19, 2011, from http//www.cdc.gov/p
  arasites/onchocerciasis/prevention.html

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Treatment and Prevention Contd..
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River blindness control programs

• Onchocerciasis Control Program (OCP) 1974
  (Levine, 2007)
• Onchocerciasis Elimination Program for the
  Americas (OEPA) 1992 (WHO, 2011)
• African Program for Onchocerciasis Control (APOC)
  1995 (Levine, 2007).
• Levine, R. (2007). Controlling Onchocerciasis
  (River Blindness) in Sub-Saharan Africa. In
  Series Editor Richard Riegelman. Case Studies in
  Global Health Millions saved, 49-56. Sudbury,
  Massachusetts Jones and Bartlett.
•  
• World Health Organization. (2011). Prevention of
  blindness and visual impairment Onchocerciasis
  elimination program for the Americas (OEPA).
  Retrieved August 8, 2011, from http//www.who.int/
  blindness/partnerships/onchocerciasis_oepa/en/inde
  x.html

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Key Learning goals

• Understanding the cause and pattern of spread of
  river blindness
• Understanding the environmental components of
  river blindness
• Understanding the extent of the problem, and its
  prevention and management
• Understanding how prevention of spread of river
  blindness can result in social change considering
  the achievements of OCP, OEPA, and APOC

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QUESTIONS   DISCUSSIONS
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References

• Centers for Disease Control and Prevention.
  (2011). Fact sheet for general public health
  River blindness (Onchocerciasis). Retrieved July
  19, 2011, from http//www.wellnessproposals.com/he
  alth-care/handouts/parasitic-zoonotic-diseases/onc
  hocerciasis-factsheet.pdf
• Centers for Disease Control and Prevention.
  (2011). Onchocerciasis Prevention and Control.
  Retrieved July 19, 2011, from http//www.cdc.gov/p
  arasites/onchocerciasis/prevention.html
• Levine, R. (2007). Controlling Onchocerciasis
  (River Blindness) in Sub-Saharan Africa. In
  Series Editor Richard Riegelman. Case Studies in
  Global Health Millions saved, 49-56. Sudbury,
  Massachusetts Jones and Bartlett.
• Lucas, A., Gills, H. (1990). A new short
  textbook of preventive medicine for the tropics.
  (3rd ed.). Kent, UK Edward Arnold
• World Health Organization. (2011). Onchocerciasis
  disease information Prevention of Blindness and
  visual impairment. Retrieved July 18, 2011
  fromhttp//www.who.int/blindness/partnerships/onch
  ocerciasis_disease_information/en/index.html
• World Health Organization. (2011). Prevention of
  blindness and visual impairment. Priority eye
  disease Onchocerciasis (river blindness).
  Retrieved July 19, 2011, from http//www.who.int/b
  lindness/causes/priority/en/index3.htmt
• World Health Organization. (2011). Prevention of
  blindness and visual impairment Onchocerciasis
  elimination program for the Americas (OEPA).
  Retrieved August 8, 2011, from http//www.who.int/
  blindness/partnerships/onchocerciasis_oepa/en/inde
  x.html

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Further reading

• Global network. Neglected tropical diseases.
  Onchocerciasis. http//globalnetwork.org/about-ntd
  s/factsheets/onchocerciasis
• Helen Keller International. Onchocerciasis
  control. http//www.hki.org/preventing-blindness/o
  nchocerciasis-control/
• TDR For research on disease of poverty.
  Onchocerciasis. http//apps.who.int/tdr/svc/diseas
  es/onchocerciasis
• The Carter Center. Onchocerciasis elimination
  program of the Americas. http//www.cartercenter.o
  rg/health/river_blindness/oepa.html
• TropIKA.net. Tropical disease research to foster
  innovation and knowledge application.
  Onchocerciasis. http//www.tropika.net/svc/home/on
  chocerciasis

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