Gorilla Doctors

Category: Field Procedures, Monitoring Visits | Date: Jan 13 2009 | By: Dr. Jan Ramer for gorilladoctors

During my recheck of Mushya and Icyizere the day after the intervention, I kept an eye out for fresh fecal samples. We wanted to follow the pattern of parasites now that we’d given the ivermectin. Icyizere had conveniently produced several samples within minutes of my arrival in the group. I’d brought one of them back to the lab for microscopic examination. I found—no surprise—that it was still loaded with parasites. But I had the impression that there were many more worm fragments than whole ones. Maybe the ivermectin had already killed some of the adults.

Mushya, six days post treatment

There’s no question that anti-parasitic drugs work quickly. They can kill larvae and adult worms within hours of being absorbed into the bloodstream. The worms feed on the animal’s blood, which is what causes the anemia. But these drugs have no effect on the worm eggs. For this reason, the usual recommendation is to repeat the de-worming treatment after three to four weeks, allowing time for the eggs to hatch. The second dose finishes them off, unless—and this is a crucial point—the animal is re-exposed.

Mushya with Icyizere, 6 days post treatment

Repeating our treatment was certainly possible, though I didn’t like to think of doing the whole difficult procedure again any time soon. Alternatively, we could simply dart Icyizere with more ivermectin. By keeping her parasite load down, we could decrease Mushya’s risk of re-infection. But these parasites are everywhere in the environment. Since most habituated wild mountain gorillas have them, there’s no way we can eliminate the parasites. We can only buy time for Mushya’s anemia to resolve and his body condition to improve. Again, we still don’t know why this infant had such a problem in the first place.

Mushya reaching for plants to nibble on, with Icyizere, 6 days post treatment

Given that Icyizere’s mammary glands were small when compared (visually) to those of most other mothers, Mushya’s primary problem still could be lack of milk. On the other hand, maybe Icyizere wasn’t producing enough milk because of her own huge parasite load. But why did she have so many? To quote an overused but appropriate cliché, parasite problems often pose the question of what came first, the chicken or the egg. Either way, we’d give the gorilla pair a few weeks to respond before considering further treatment.

We checked Icyizere again early the next week, along with the rest of Isabukuru group. As expected, everyone in the family had two of the same parasites we’d found in Icyizere and Mushya: a strongyle-type nematode and a tapeworm known as anoplocephala. Some, Icyizere and Mushya, also had eggs and worm segments of a third type (another kind of nematode) known as a trichostrongyle-type. Of the three types of worm (we won’t know their exact species until we get samples out to the experts), the trichostrongyle was of the most concern. These worms cause intestinal ulceration and anemia in many species. Among mountain gorillas who died from other causes, these parasites have often been found embedded in the stomach wall.

Mushya with Icyizere, 6 days post treatment

The day after Christmas, six days after treatment, I made my next check of Mushya and Icyizere. The infant spent most of my two-hour observation period grabbing bits of plant material and trying to get them into his mouth, while Icyizere ate voraciously. Sometimes she’d even bat his tiny hands away from her food. He nibbled for a long time on a big root—I think it was from a thistle plant. At one point, he opened his mouth wide enough for me to check his gum color. It was still very pale, but with a hint of pink. What a great gift for the holidays!

Mushya crawling on Icyizere’s back, 6 days post-treatment

When Magda first checked Mushya two months ago, she’d noticed the absence of a crucial normal behavior: Mushya never rode on his mother’s back. He was too weak. Instead, Icyizere had tufts of hair missing from the area over both hips, where he’d been clinging to her for months. Twice during this day’s visit, I saw him try to climb up and sit on her shoulders. After a minute or so, Icyizere pulled him down with one big hand, settling him back into the crook of her elbow while she ate. No doubt she sensed that he was still too weak to stay up there for long. Still, I finally accepted the evidence of my own eyes: Mushya was better. I practically skipped down the mountain.

Mushya, 2 weeks post-treatment

After another week, I returned to check mother and infant again. It was a clear, dry morning, the second day of January 2009, and I’d figured out that Mushya’s name meant “new.” Kinyarwanda for Happy New Year is “Umwaka Mushya Muhire.” Literally, the words mean, Year New Happy.

Mushya with Icyizere, 2 weeks post-treatment

When I arrived at the group, the gorillas were resting in the warm sunshine. The bright light made Mushya’s scruffy coat of hair look somewhat worse to me, except that it had a shine to it I hadn’t seen before. Nor was he itchy. He gazed at me while Icyizere groomed him. As soon as she finished, he began to play in her lap, letting himself drop to the ground and then climbing back up again.

Ikaze with Mushya, 2 weeks post-treatment

Icyizere got up and moved a short distance, repositioning herself next to Isabukuru, the silverback. At first, Mushya crawled around on his mother’s belly. Then he then inched his way over to Isabukuru and patted his father’s head a few times. One of the other females in the group, Ikaze, walked over and picked Mushya up. She sat down a few feet away, holding him in her lap. I guessed she’d been waiting for her opportunity. When Isabukuru got up to leave and the females followed, Ikaze kept the infant for a few yards, then handed him off to another female, Muntu. This is normal behavior among gorillas, but I hadn’t seen it happen during my last three visits. The family must sense that their infant—he’s the only one in the group of seven—is stronger.

Mushya crawling around between Icyizere (right) and Isabukuru (left), 2 weeks post-treatment

A short distance down the trail, Isabukuru sat down to eat berries and Icyizere took another short rest in the sunshine. Mushya crawled out of her lap and motored around on the ground for several minutes. This was another first—and a very appropriate start for the New Year!

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