EPIDEMIOLOGY AND CONTROL OF HELMINTHIC INFESTATION (contd.)

1. EPIDEMIOLOGY AND CONTROL OF HELMINTHIC INFESTATION (contd.) Dr. Igbinedion MBBS, MPH, FRSPH, ACIEH

2. Schistosomiasis • AKA Bilharziasis • Caused by Schistosoma spp.- mansoni, haematobium, japonicum, intercalatum and mekongi- which affect humans • It is a parasitic infection • Snails are the intermediary agents between hosts • Infection is by consuming water contaminated by infected snails • Commonly found in Asia, Africa and South America

3. Schistosomiasis (contd.) • Affects children more than adults • Second most devastating parasitic disease socioeconomically, after malaria • Infection 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

4. Schistosomiasis (contd.) • Life cycle- Snail and Man

5. Schistosomiasis (contd.) • Signs and Symptoms- acute or chronic (acute- occurs within a few weeks of infection) • abdominal pain • diarrhea • eosinophilia • hepatosplenomegaly • esophageal varices • skin symptoms- itchingand dermatitis • CNS involvement • Bladder cancer

6. Schistosomiasis (contd.) • Diagnosis • Detection using ELISA- highly effective • Stool and urine microscopy • Prevention • Eliminate snails that dwell in the water using acrolein, copper sulfate or niclosamide • Avoiding the snails • Treatment • Praziquantel

7. Strongyloidiasis • Caused by Strongyloidesstercoralis, 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

8. Strongyloidiasis (contd.)

9. Strongyloidiasis (contd.) • Clinical Features • Mostly asymptomatic • Abdominal pain • Bloating, heartburn • Diarrhea, constipation • Nausea • Loss of appetite • Cough • Itchy, red rash

10. Strongyloidiasis (contd.) • Diagnosis • Stool microscopy • Treatment • Ivermectin- drug of choice • Thiabendazole • Albendazole

11. Strongyloidiasis (contd.) • Prevention and control • Wear shoes • Good hygiene • Proper sewage disposal

12. Filariasis • Causes lymphatic filariasis • Caused by Wuchereriabancrofti- most common worldwide; In Asia- Brugiamalayi and Brugiatimori • Nematode (roundworm) • More common in tropical and sub tropical areas • Infection is spread through mosquito bites from person to person • Mosquitoes involved- in Africa, Anopheles mosquitoes; in the Americas, Culexquinquefasciatus; in the Pacific and Asia, Aedes and Mansonia

13. LIFECYCLE OF Wuchereriabancrofti

14. Lifecycle of Brugiamalayi

15. Filariasis (contd.) • Clinical Features • Usually asymptomatic • Lymphedema in a small percentage of patients- legs, arms, breast, genitalia • Elephantiasis- hardened and thick- ened skin from bacterial infection • Hydrocele or scrotal swelling- W. bancrofti

16. 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 • Treatment • Diethylcarbamazine (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

17. Filariasis (contd.) • Prevention and control • Avoid mosquito bites- within dusk and dawn, when they bite • Protective clothing • Mosquito repellant • Mosquito nets

18. Loaisis • Caused by Loa loa • Nematode (roundworm) in the Lymphatics and subcutaneous tissues • AKA African eye worm • Transmitted through repeated bites of deerflies which breed in muddy, shaded areas along rivers • Found in West and Central Africa • The deerflies bite during the day and are attracted by movement and smoke • More common in rainy season

19. Lifecycle Loa loa

20. Loiasis (contd.) • Clinical Features • Asymptomatic • Calabar 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 itching • Muscle and joint pain • Fatigue

21. 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 • Treatment • Surgical removal of migrating adult worm from skin or eye • DEC- kills larvae and adult worm • Albendazole- kills adult worm

22. Loiasis(contd.) • Prevention and control • DEC weekly • Avoiding breeding sites and smoke • Personal protection- protective clothing, repellants

23. Onchocerciasis • AKA River Blindness • Caused by Onchocerca volvulus • Nematodes in the subcutaneous tissues • Transmission 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

24. Onchocerca volvulus Lifecycle

25. Onchocerciasis (contd.) • Clinical features • Soma are asymptomatic • Skin rashes, itchy • Subcutaneous nodules • Visual changes • Leopard skin appearance from long term inflamed and itchy skin • Hanging groin- loss of skin elasticity • Blindness- from inflammatory reaction of dead larva in the eye

26. Onchocerciasis (contd.) • Diagnosis • Skin snip from different parts of the body • Examination of a surgically removed nodule • Eye examination • Treatment • Ivermectin • Before administering medication, ensure there is no Loa loa infection because it can cause severe side effects to medications for Onchocerciasis.

27. Onchocerciasis (contd.) • Prevention and control • Personal protective measures are the most important • Mass treatment with ivermectin

28. References • http://www.cdc.gov/parasites/schistosomiasis/ • http://www.cdc.gov/parasites/strongyloides/ • http://www.cdc.gov/parasites/lymphaticfilariasis/ • http://www.cdc.gov/parasites/loiasis/ • http://www.cdc.gov/parasites/onchocerciasis/index.html