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EPIDEMIOLOGY AND CONTROL OF HELMINTHIC INFESTATION (contd.). Dr. Igbinedion MBBS, MPH, FRSPH, ACIEH. Schistosomiasis. AKA Bilharziasis Caused by Schistosoma spp.- mansoni , haematobium , japonicum , intercalatum and mekongi - which affect humans It is a parasitic infection - PowerPoint PPT Presentation
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Dr. Igbinedion
MBBS, MPH, FRSPH, ACIEH
EPIDEMIOLOGY AND CONTROL OF HELMINTHIC
INFESTATION (contd.)
AKA BilharziasisCaused by Schistosoma spp.- mansoni,
haematobium, japonicum, intercalatum and mekongi- which affect humans
It is a parasitic infectionSnails are the intermediary agents between
hostsInfection is by consuming water contaminated
by infected snailsCommonly found in Asia, Africa and South
America
Schistosomiasis
Affects children more than adultsSecond most devastating parasitic disease
socioeconomically, after malariaInfection is gotten when individuals-
particularly children- come in contact with contaminated water, either by playing or swimming
The parasitic larva then penetrate the skin and mature within the organs
Schistosomiasis (contd.)
Life cycle- Snail and Man
Schistosomiasis (contd.)
Signs and Symptoms- acute or chronic (acute- occurs within a few weeks of infection)
abdominal paindiarrheaeosinophilia hepatosplenomegalyesophageal varicesskin symptoms- itching and dermatitisCNS involvementBladder cancer
Schistosomiasis (contd.)
DiagnosisDetection using ELISA- highly effectiveStool and urine microscopy
PreventionEliminate snails that dwell in the water
using acrolein, copper sulfate or niclosamideAvoiding the snails
TreatmentPraziquantel
Schistosomiasis (contd.)
Caused by Strongyloides stercoralis, a roundworm
More common in tropics and warm temperate regions
Infection is through contact with soil contaminated by Strongyloides larvae
Low socioeconomic factors and institutionalized populations are risk factors
Strongyloidiasis
Strongyloidiasis (contd.)
Clinical FeaturesMostly asymptomaticAbdominal painBloating, heartburnDiarrhea, constipationNauseaLoss of appetiteCoughItchy, red rash
Strongyloidiasis (contd.)
DiagnosisStool microscopy
TreatmentIvermectin- drug of choiceThiabendazoleAlbendazole
Strongyloidiasis (contd.)
Prevention and controlWear shoesGood hygieneProper sewage disposal
Strongyloidiasis (contd.)
Causes lymphatic filariasisCaused by Wuchereria bancrofti- most common
worldwide; In Asia- Brugia malayi and Brugia timori
Nematode (roundworm)More common in tropical and sub tropical areasInfection is spread through mosquito bites from
person to personMosquitoes involved- in Africa, Anopheles
mosquitoes; in the Americas, Culex quinquefasciatus; in the Pacific and Asia, Aedes and Mansonia
Filariasis
LIFECYCLE OF Wuchereria bancrofti
Lifecycle of Brugia malayi
Clinical FeaturesUsually asymptomaticLymphedema in a small percentage of
patients- legs, arms, breast, genitaliaElephantiasis- hardened and thick- ened skin from bacterial infectionHydrocele or scrotal swelling- W. bancrofti
Filariasis (contd.)
Diagnosis Identifying microfilaria in the blood using
microscopy. Blood sample should be taken at night because that is when the microfilaria circulate
Serology
TreatmentDiethylcarbamazine (DEC)For lymphedema, there is no active filarial infection
so DEC is not indicated- Refer to lymphedema therapist for education on hygiene and exercise
Surgery for hydrocele
Filariasis (contd.)
Prevention and control
Avoid mosquito bites- within dusk and dawn, when they bite
Protective clothingMosquito repellantMosquito nets
Filariasis (contd.)
Caused by Loa loaNematode (roundworm) in the Lymphatics
and subcutaneous tissuesAKA African eye wormTransmitted through repeated bites of
deerflies which breed in muddy, shaded areas along rivers
Found in West and Central AfricaThe deerflies bite during the day and are
attracted by movement and smokeMore common in rainy season
Loaisis
Lifecycle Loa loa
Clinical FeaturesAsymptomaticCalabar swellings- local angioedema (non
tender found on limbs and near joints); associated with itching
Eye worm- itching, pain photophobia. Usually lasts hours and does not damage the eye
Generalized itchingMuscle and joint painFatigue
Loiasis (contd.)
Diagnosis Identifying the adult worm in the eye Identifying larvae in the blood taken between
10am and 2pm Identifying the worm after removal from the body
TreatmentSurgical removal of migrating adult worm from
skin or eyeDEC- kills larvae and adult wormAlbendazole- kills adult worm
Loiasis (contd.)
Prevention and controlDEC weeklyAvoiding breeding sites and smokePersonal protection- protective clothing,
repellants
Loiasis (contd.)
AKA River BlindnessCaused by Onchocerca volvulusNematodes in the subcutaneous tissuesTransmission is through repeated bites of
Simulium blackflies which breeds near fast flowing rivers and streams and bite during the day
Found in the tropics especially sub Saharan Africa
Onchocerciasis
Onchocerca volvulus Lifecycle
Clinical featuresSoma are asymptomaticSkin rashes, itchySubcutaneous nodulesVisual changesLeopard skin appearance from long term
inflamed and itchy skinHanging groin- loss of skin elasticityBlindness- from inflammatory reaction of
dead larva in the eye
Onchocerciasis (contd.)
DiagnosisSkin snip from different parts of the bodyExamination of a surgically removed noduleEye examination
TreatmentIvermectinBefore administering medication, ensure there
is no Loa loa infection because it can cause severe side effects to medications for Onchocerciasis.
Onchocerciasis (contd.)
Prevention and control
Personal protective measures are the most important
Mass treatment with ivermectin
Onchocerciasis (contd.)
http://www.cdc.gov/parasites/schistosomiasis/http://www.cdc.gov/parasites/strongyloides/http://www.cdc.gov/parasites/lymphaticfilaria
sis/
http://www.cdc.gov/parasites/loiasis/http://www.cdc.gov/parasites/onchocerciasis/
index.html
References