1. NEMATOEDES ----Enterobius vermicularis and Filarial parasites
Characteristics of Nematodes (Adult)
Enterobius vermicularis
Wuchereria bancrofti and Brugia malayi

2. Characteristics of Nematodes
Cylindrical and unsegmented
Dioecious (male and female)
Complete digestive tract (mouth / esophagus / intestine / anus)
Direct life-cycle and soil-transmission (most)
e.g. Ascaris / hookworm / Enterobius
Indirect life-cycle and food or arthropods-transmission (small)
e.g. Filaria / Trichinella

4. Enterobius vermicularis
Consmopolitan, 30%~50% of the population, more prevalent in children than adults. Most common where people live under crowded conditions (orphanages / large families / kindergartens / primary school).

5. Morphology I
Adult
Female: White. 8~13 mm in size. Fusiform body with a long, thin, tapering tail. Alae (cuticular extension of head). Prominent bulb (esophagus posterior).
Male: Like female, but about 1/3 to ½ size of female. The tail is curved. Rarely seen. (Why?)

6. Morphology II
Egg
Oval, clear and colorless. 50 to 60 µm in length. Flattened on one side. Contains a larva.

7. Life cycle

8. The types of infection Infection from environment
Autoinfection: Female crawl out of anus and release eggs on the perianal region. Patients feel anus pruritus. Scratching leads to contamination of hands and nails. Then by hand-mouth result in reinfection.
Retroinfection: Some eggs hatch on the perianal skin and become larvae. They will crawlback into the anus and mature into adults.

9. Characteristic of life cycle
Human is the only host (direct life-cycle).
The location of adult: Cecum and colon.
Infective stage: Infective eggs.
The female release eggs on the perianal skin at night.
The types of infection: Autoinfection/retroinfection/infection

10. Clinical features Enterobiasis is frequently asymptomatic.
The most typical symptom is perianal pruritus, especially at night, which may lead to excoriations and bacterial superinfection. 
Occasionally, invasion of the female genital tract with vulvovaginitis and pelvic or peritoneal granulomas can occur.  Other symptoms : anorexia, irritability, and abdominal pain.

12. Laboratory Diagnosis
Microscopic identification of eggs collected in the perianal area is the method of choice by cellophane tape method for diagnosing enterobiasis.  This must be done in the morning, before defecation and washing, Alternatively, anal swabs can also be used.
Detection of adult on anal skin. 

13. Treatment and prevention
Pyrantel pamoate / Albendazole / Melbendazole. Repeated treatment
Laudering of bedding.
Pay attention to personal hygiene and eating habits

14. Filarial parasites
Filariasis(widely spread diseases) Filarial parasites Inhabit the lymphatic/subcutaneous tissue/peritoneal or throascic cavity
Mansonella ozzardi; Loa loa; Dipetalonema perstans; D.streplocerca; Onchocerca volvulus; Brugia malayi; B. timori; Wucheria bancrofti

15. Wuchereria bancrofti and Brugia malayi

16. Morphology I Adult: White and thread-like. Two rings
of small papillae on the head.
Female:5~10cm in length
Male: 2.5~4cm and a curved tail with two
copulatory spicules.

17. Morphology II
Microfilaria: 177~296 µm in length, a sheath with free endings. Bluntly rounded anteriorly and tapers to a point posteriorly. A nerve ring with no nuclei at anterior 1/5 of the body.
Wuchereria bancrofti
Brugia malayi

18. The morphological differences between two microfilaria
W.bancrofti B. malayi Size 244~296 µm 177~230 µm Cephalic space Shorter Longer Nuclei Equal sized Unequal sized clearly coalescing countable uncountable Terminal nucleus No Two

20. Life cycle

21. Nocturnal periodicity
------Phenomen which the number of microfilariae in peripherial blood is very low density during daytime, but increase from evening to midnight and reach the greatest density at 10p.m to 2 a.m. May be related to cerebral activity and vasoactivity of pulmonary vessels.

22. Characteristic of life cycle
Host: Mosqutoes (intermediate host)
Human (final host)
Location: Lymphatics and lymph nodes
Infective stage: Inective larvae
Transmission stage: Microfilariae
Diagnostic stage: Microfilariae

23. Clinical Features
Lymphatic filariasis often consists of asymptomatic microfilaremia. 
Some patients develop lymphatic dysfunction causing lymphedema and elephantiasis(in limb or scrotum).
Episodes of febrile lymphangitis and lymphadenitis may occur. 
Pulmonary tropical eosinophilia syndrome, with nocturnal cough and wheezing, fever, and eosinophilia. 

25. Laboratory Diagnosis
Microscopic examination is the most diagnostic procedure.
Fresh blood smear
Thick smear, stained with Giemsa.
Concentration techniques include centrifugation of the blood sample lyzed in 2% formalin or filtration through a Nucleopore® membrane.
Immunological tests

26. Treatment and prevention
Diethylcarbamazine (DEC) for patients and carriers.
Mass treatment in endemic areas with DEC.
DEC added to table salt (1:3000) for six months.
Elimination of mosquitoes.
Protection of people from mosquitoes biting.

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