Even with female worms, an antigen test will usually only become positive seven to eight months after infection.

The female worm still resembles a copepod and is 2 to 3 mm long.

After the male and female worms mate, the female gives birth to live microfilariae by the thousands.

In the small intestine, they molt twice and become adult female worms.

Once outside the host, the female worm dies with the eggs inside her.

About 7 days later the male and female adult worms emerge into the lumen of the duodenum.

The microfilariae produced by the female worms have a membrane "sheath".

The female worm can produce between 115,000-179,000 eggs per day.