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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

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river blindness an overview

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

presentation contents
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
expected learning outcomes
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
introduction
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/onchocerca-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/blindness/causes/priority/en/index3.htmt.

black fly similium species
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-page-main/ehow/images/a07/sa/tv/rid-biting-black-flies-800x800.jpg&imgrefurl

Lucas, A., & Gills, H. (1990). A new short textbook of preventive medicine for the tropics. (3rd ed.). Kent, UK: Edward Arnold.

lifecycle of onchocerca volvulus
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.

lifecycle of onchocerca volvulus contd
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.

lifecycle of onchocerca volvulus contd1
Lifecycle of Onchocerca volvulus Contd...

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

eye lesions
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/onchocerciasis

Retina in Onchocerciasis. Retrieved from, http://www.sciencephoto.com/media/260256/enlarge

Lucas, A., & Gills, H. (1990). A new short textbook of preventive medicine for the tropics. (3rd

ed.). Kent, UK: Edward Arnold.

spread of river blindness
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/4022-20850

Holiday makers. Retrieved from, http://www.crete-connections.com/Crete-Accommodation.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/health-care/handouts/parasitic-zoonotic-diseases/onchocerciasis-factsheet.pdf

people at risk for river blindness
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/africatraveltips/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/health-care/handouts/parasitic-zoonotic-diseases/onchocerciasis-factsheet.pdf

epidemiology
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/health-care/handouts/parasitic-zoonotic-diseases/onchocerciasis-factsheet.pdf

public health burden of river blindness
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/onchocerciasis_disease_information/en/index.html

diagnosis
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/ParaSites2006/Onchocerciasis/Diagnosis.html

Laboratory scientist at work. Retrieved from, http://www.fmcowerri.com/departments-and-units/microbiology/

Centers for Disease Control and Prevention. (2011). Parasites – Onchocerciasis: Diagnosis. Retrieved August 8, 2011, from http://www.cdc.gov/parasites/onchocerciasis/diagnosis.html

prevention and treatment
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/onchocerciasis_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/parasites/onchocerciasis/prevention.html

treatment and prevention contd
Treatment and Prevention Contd..

Covered up missionaries. Retrieved from, http://www.mafrome.org/ireland124.htm

Covered up peace volunteers. Retrieved from, http://ilint.illinois.edu/iir/online/illinois_in_the_world/

Ivermectin. Retrieved from, http://image.made-in-china.com/2f0j00fekTaSUcuozt/Ivermectin-Injection-1-50ml-100ml-Ivermectin-Drench-YN-002-.jpg

Patient attending her doctor. Retrieved from http://www.wellsphere.com/skin-health-article/will-the-last-medical-dermatologist-please-turn-off-the-lights-access-issues-for-dermatology-patients/724742

river blindness control programs
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/index.html

key learning goals
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
slide19

QUESTIONS

DISCUSSIONS

references
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/health-care/handouts/parasitic-zoonotic-diseases/onchocerciasis-factsheet.pdf

Centers for Disease Control and Prevention. (2011). Onchocerciasis: Prevention and Control. Retrieved July 19, 2011, from http://www.cdc.gov/parasites/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/onchocerciasis_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/blindness/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/index.html

further reading
Further reading

Global network. Neglected tropical diseases. Onchocerciasis. http://globalnetwork.org/about-ntds/factsheets/onchocerciasis

Helen Keller International. Onchocerciasis control. http://www.hki.org/preventing-blindness/onchocerciasis-control/

TDR For research on disease of poverty. Onchocerciasis. http://apps.who.int/tdr/svc/diseases/onchocerciasis

The Carter Center. Onchocerciasis elimination program of the Americas. http://www.cartercenter.org/health/river_blindness/oepa.html

TropIKA.net. Tropical disease research to foster innovation and knowledge application. Onchocerciasis. http://www.tropika.net/svc/home/onchocerciasis