RIVER BLINDNESS (An Overview) CHINEDU UMEADI (Ph.D. Student) Walden University PUBH-8165-1 Instructor: Dr Stephen Arnold Spring Quarter, 2011 ------------------------------------------------------------------

RIVER BLINDNESS(An Overview)

CHINEDU UMEADI (Ph.D. Student)Walden University

PUBH-8165-1Instructor: Dr Stephen Arnold

Spring Quarter, 2011------------------------------------------------------------------

Adult black fly feeding on skin. Retrieved from, http://www.canadatrip.co.ukAdult man suffering with river blindness. Retrieved from, http://www.goldbamboo.com/pictures-t2344.html

Presentation ContentsIntroductionBlack fly (Similium species)Life cycle of Onchocerca volvulusEye lesionSpread of river blindnessPeople at risk for river blindnessEpidemiologyPublic health burdenDiagnosisPrevention & TreatmentQuestions and Discussions

Expected Learning OutcomesMeaning of river blindness

Cause and pattern of spread of river blindness

Extent of the problem

Prevention and management of river blindness

IntroductionA 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)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. (3 rd ed.). Kent, UK: Edward Arnold.

Lifecycle of Onchocerca volvulusSimilium 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


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 Contd...

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

Eye lesionsCaused 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


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 blindnessPeople 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/


EpidemiologySome 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


Public health burden of river blindnessGlobal 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

DiagnosisSkin 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 treatmentNo 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..

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 programsOnchocerciasis 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 goalsUnderstanding 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

QUESTIONS

DISCUSSIONS

References


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 readingGlobal 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

Documents

RIVER BLINDNESS (An Overview) CHINEDU UMEADI (Ph.D. Student) Walden University PUBH-8165-1 Instructor: Dr Stephen Arnold Spring Quarter, 2011 ------------------------------------------------------------------