TISSUE NEMATODES COMMON TISSUE NEMATODE INFECTIONS Trichinella spiralis

COMMON TISSUE NEMATODE INFECTIONS • Trichinella spiralis adults in small intestine larvae in tissues

Trichinosis Pathology: Adults cause mild gastroenteritis. Larvae cause fever, myositis and multi-system involvement which

Most prevalent in areas where domestic pigs are allowed to roam freely.

Visceral larva migrans: • Mainly affects children who eat soil contaminated with emberyonated (infective)

• Pathology: Eosinophilia, hepatomegaly, retinitis. • Diagnosis: serology, biopsy. • Treatment: Albendazole

Draunculiasis Caused by Dracunculus medinensis Adult female lives in subcutaneous tissues, causing a skin

FILARIAL WORMS: (Adult worms + microfilariae) 1. Onchocerca volvulus: Adults in subcutaneous swellings Microfilariae

Onchocerciasis (river blindness) Pathology: Adults worms live in subcutaneous nodules. Main pathology caused by

LYMPHATIC FILARIASIS Mainly caused by Wuchereria bancrofti and Brugia malayi Pathology: Due to adult

LYMPHATIC FILARIASIS Diagnosis: detection of microfilariae in blood in early stages of the disease:

Loiasis • Pathology: Adult worm continously migration in subcutaneous and subconjuntival tissues, causing Calabar

Loiasis • Diagnosis: detection of microfilariae in blood film. • Treatment: diethylcarbamazine (DEC) or

NON-FILARIAL TISSUE NEMATODE INFECTIONS Nematode species Disease Mode of transmission Location in human Diagnosis

MAJOR FILARIAL INFECTIONS OF HUMANS species Disease Geographic distribution Location of adult in humans

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TISSUE NEMATODES

COMMON TISSUE NEMATODE INFECTIONS • Trichinella spiralis adults in small intestine larvae in tissues (mainly in muscles). • Toxocara canis (dog roundworm) larvae in organs (liver brain eyes), causing visceral larva migrans • Dracunculus medinensis (guinea worm) adult female in subcutaneous tissues • Filarial worms

Trichinella spiralis

Trichinosis

Trichinosis Pathology: Adults cause mild gastroenteritis. Larvae cause fever, myositis and multi-system involvement which may lead to death. Diagnosis: serology, muscle biopsy. Treatment: Albendazole or Mebendazole + corticosteroids

Trichinosis

Most prevalent in areas where domestic pigs are allowed to roam freely.

Visceral larva migrans: • Mainly affects children who eat soil contaminated with emberyonated (infective) eggs of Toxocara canis. • Larvae do not develop in humans but migrate continuously in viscera and encapsulate, causing tissue damage.

Toxocara canis

• Pathology: Eosinophilia, hepatomegaly, retinitis. • Diagnosis: serology, biopsy. • Treatment: Albendazole

Dracunculus medinensis

Draunculiasis Caused by Dracunculus medinensis Adult female lives in subcutaneous tissues, causing a skin ulcer through which it protrudes its anterior end. Main pathology due to secondary bacterial infection and allergic reactions. Diagnosis: clinical picture. Treatment: surgical removal.

FILARIAL WORMS: (Adult worms + microfilariae) 1. Onchocerca volvulus: Adults in subcutaneous swellings Microfilariae : mainly in skin, eyes causing River blindness 2. Wuchereria bancrofti, Brugia malayi & B. timori: Lymphatic filariasis (adults in lymphatics, microfilariae in blood) 3. Loa loa: Adults in subcutaneous and subconjunctival tissues, causing Calabar swellings. Microfilariae in blood

FILARIALIASIS )

Loiasis

Onchocerciasis (river blindness) Pathology: Adults worms live in subcutaneous nodules. Main pathology caused by microfilariae in: • Skin: dermatitis • Lymph nodes: lymphadenopathy • Eyes: blindness Diagnosis: skin snip to identify microfilariae. Treatment: Ivermectin

LYMPHATIC FILARIASIS

Lymphatic Filariasis

LYMPHATIC FILARIASIS Mainly caused by Wuchereria bancrofti and Brugia malayi Pathology: Due to adult worm obstructing lymphatics. • Acute: lymphadenitis lymphatic varices • Chronic: lymphedema, hydrocele, chyluria.

LYMPHATIC FILARIASIS Diagnosis: detection of microfilariae in blood in early stages of the disease: Blood film, Knott’s method ( concentration of 1 ml of blood), best 10 pm to 2 am (nocturnal periodicity). Immunological tests: Treatment: diethylcarbamazine (DEC) or ivermectin

Loa loa

Loiasis

Loiasis • Pathology: Adult worm continously migration in subcutaneous and subconjuntival tissues, causing Calabar swellings (allergic reactions) and conjunctivitis.

Loiasis • Diagnosis: detection of microfilariae in blood film. • Treatment: diethylcarbamazine (DEC) or ivermectin, surgical remonval.

NON-FILARIAL TISSUE NEMATODE INFECTIONS Nematode species Disease Mode of transmission Location in human Diagnosis treatment Dracunculus Dracunculias Ingestion of is, Guinea medinensis infected worm disease cyclops in water Subcutaneous, mainly in lower limbs clinical Surgical extraction Trichinella spiralis Trichinellosi s (trichinosis) ingestion larvae in undercooked pork Muscles, lungs brain Serology, muscle biopsy albendazole Toxocara canis Visceral larva migrans Ingestion of infective eggs in soil Abdominal organs and brain Serology, ELISA albendazole

MAJOR FILARIAL INFECTIONS OF HUMANS species Disease Geographic distribution Location of adult in humans Location of microfilaria vector Lab. diagnosis Wuchereria elephantiasis bancrofti Tropical and subtropical areas Lymphatic vessels Blood (nocturnal periodicity) mosquitoes Blood film Brugia malayi elephantiasis Asia Lymphatic vessels Blood (nocturnal periodicity) mosquitoes Blood film Onchocerc a volvulus Onchocerciasis (river blindness) Africa, Subcutaneous Central and nodules South America, Yemen Skin, eyes, no periodicity Simulium spp. (black fly) Skin snip Loa loiasis Central Africa Chrysops spp. (deer fly) Blood film Moving in Blood subcutaneous (diurnal tissues periodicity)