Pete Dixon

It's been a rapid few days of learning about hookworm incubation. Here's what more I've learned. Most importantly, any microscope that can do 40X will suffice.

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That's because it turns out the concern about the distance from the lens to the plate for pipetting was a red herring. All one needs to do is lay down a bunch of very small drops on the slide or Petri dish and use the microscope to find drops that have the required number of larvae. Note the placement of the drops, remove the slide or dish from the scope and transfer the target drops by pipette to a container or gauze bandage for immediate use. Use water with the same pipette again to catch any stragglers. Job done. No fancy pipette work or counting required. Since most inoculations people do are between 3–15 larvae, probably only 1–5 drops will be needed with a total work time of just 10 minutes or less.

As point of clarification from my last post, all this depends on having a hookworm egg infected stool sample, which means previously having bought or otherwise obtained larvae and self-inoculated.

It probably takes a month or more before these hookworms mature and start producing eggs in the stool. For me, I get symptom relief from my GI issues for 5–6 months post inoculation before I need to re-inoculate, and I've been using 25 larvae. I'm considering changing my routine to 5 larvae inoculations every month, or 10 every two months, that way I'm unlikely to be caught out not having hookworms in my system producing eggs. Incubations sometimes fail for known and unknown reasons, so this monthly or semi-monthly strategy would be more failure tolerant. It's possible older hookworms still are there laying eggs after symptom relief ends, but that's not something I'd prefer to bet on (Wikipedia is unclear on hookworm longevity). 

Total work per cycle seems to be about 20–30 mins, that's with collecting the stool sample, setting up the jar, then harvesting, applying the larvae and cleaning up. Ongoing incubation costs are minimal, and it will be nice not having to fork out $200 CAN like I was per cycle.

It's almost anti-climactic having all this figured out now. I had thought it was going to be much harder than it turned out to be.