Diversity-lah! One Health in Malaysia

A Malaysian black fly in the genus Simulium.
Photo credit: Zubaidah Ya'cob.

Dr. Zubaidah Ya'cob is a black fly taxonomist. Or is she a bird ecologist? A parasitologist? Or perhaps a medical researcher looking at River Blindness? Such is the label of a One Health researcher: messy, flexible, shifting among disciplines to answer a tangled question.

Dr. Ya'cob peers at a black fly preserved in ethanol.

This poster behind Dr. Ya'cob's desk explains how bird species use degraded forest habitat, evidence of her shifting research focus since graduate school.

I made contact with Dr. Ya'cob, who prefers the nickname Izu, through that heavenly and hellish tool, Facebook. A quick Google led me to the Malaysian Nature Society, an active group of birders, herpers, photographers, hikers, and environmentalists living all over Malaysia. I posted a message asking for birding buddies and disease scientists. Within minutes, I had been invited to a Raptor Watch Festival, an ant-tree symbiosis lab, a three-day field trip to Tasik Kenyir National Park, and a guest lecture at Monash University (in which I was the guest lecturer.) Most importantly for today's post, I was invited to Dr. Ya'cob's black fly lab at Universiti Malaya, the oldest university in the country.

Many Malay words are phonetically-spelled English. The Fakulti Sains is the Science Department!

Dr. Ya'cob showed me her lab, an open space filled with half a dozen desks, empty for the moment. "I like the open floor plan," she told me. "All my colleagues work in here. I don't like to be isolated." That mentality flows into her One Health perspective. By definition, One Health is an intersection of three fields: human medicine, veterinary medicine, and environmental science. Nobody can do it alone.

Dr. Ya'cob introduced her microscopes to me as her "two best friends."

She started explaining black fly species, and I had to hit rewind. Why was she studying black flies? What's this about River Blindness? Start from the beginning, please!

A few fly species from a poster in Dr. Ya'cob's lab.

You'll get to the real-life fly photos if you keep scrolling!

Here's the story. In Africa there is a disease called River Blindness. At least 500,000 people are completely blind from it, and many more suffer impaired vision. A microscopic worm is to blame: the Filarioid roundworm called Onchocerca vulvulus.

Photos of Onchocerca vulvulus in a book written by Dr. Ya'cob's mentor.

The disease also exists in South America, because O. vulvulus snuck in from Africa on slave-trading ships in the 1600s. In Ecuador, River Blindness has the largest impact on indigenous Amazonian tribes. Dr. Ya'cob's mentor, Dr. Hiroyuki Takaoka, found that 90% of Yanomami people are infected.

Dr. Hiroyaki Takaoka, or Hiro, has spent his career studying black flies in Japan, Ecuador, and Malaysia. Dr. Ya'cob introduced him to me as her sensei, the Godfather of black fly research.

But where do flies come in? I'm so glad you asked! Black flies are the vector of this tiny worm. They reflux it through their mouthparts into humans as they suck our blood. Unlike mosquitoes, which prefer stagnant water, black flies breed in flowing, unpolluted streams. That's why the disease is called "River Blindness" -- you're more likely to catch it if you hang around rivers.

Dr. Ya'cob patiently explains black fly ecology.

Flies of all kinds belong to the order Diptera, which means "two wings" in Latin. (Could apply to a lot of things, right? Birds, butterflies, airplanes... but no, just the flies!) Within that order is a family called Simulidae, the black flies. (No, they are not all black, in case you were wondering.) There are 37 genera within that family, but only one lives in the Oriental region: the genus Simulium.

Dr. Ya'cob moves a tiny black fly into focus in a Petri dish. She says the ethanol fumes make her sleepy -- just one more challenge in this difficult job.

Now, you might be wondering why a professor in Malaysia is studying an African and South American disease. Currently, River Blindness doesn't occur in Southeast Asia --- but it could arrive anytime, and when it does, it could spread through the native Simulium black flies.

In 2013, this lab discovered a single case of Onchocerca dewitti (a related species of Filarioid roundworm that does not affect humans) in a Malaysian wild boar. Since then, Dr. Ya'cob has been on the hunt for O. dewitti's vector. Which black fly is the culprit? Who spreads roundworms among Malaysia's wild boar? This question matters to more than those scruffy swine in the jungle (no offense, wild boar --- we love you too), because if O. vulvulus arrives in Southeast Asia, it's likely to hitch a ride in the same species of black fly.

That's why Dr. Ja'cob spends her days catching miniscule black flies in a net and painstakingly dissecting their thoraxes in search of O. vulvulus worms. The hardest part: "The flesh is white, just like the worms!" So far she hasn't found any, but she's not discouraged. "I just have to increase the efforts," she resolved.

My one attempt to photograph a black fly through the microscope. This little guy is off the hook -- no Filarioid roundworms were found in his species.

In the process of settling the taxonomy of black flies in Malaysia, Dr. Ya'cob has described five new species. She showed me the pencil sketches she drew for each fly's body parts. They were incredibly detailed artwork.

The pencil drawings are converted to digital images by a graphic design team for publication.

Dr. Ya'cob lovingly handles the original drawings that were published in her recent description of a new black fly species.

If O. vulvulus does come to Malaysia, it will be very important to know which black fly is the vector. In Africa, a biological control agent called BTI is sprayed on the streams to kill black fly larvae and nymphs. BTI stands for Bacillus turgiensis israelensis, a larvae-eating bacterium. You know what they say: a pathogen of a pathogen is a friend!

Black flies are particular about their streams. Different species require different conditions: fast-flowing or slow, large or small, extremely hot or just warm or frigid. By knowing which black fly species are vectors, Malaysian scientists will be able to spray BTI on only those streams preferred by the vector species. "No need to harm other species of black fly that live in other habitats," Dr. Ya'cob explained.

Amazing how a tiny insect can wreak such havoc.

Wow, they get so much more interesting under a scope!
Photo credit: Zubaidah Ya'cob.

You don't look very black to me, little black fly.
Photo credit: Zubaidah Ya'cob.

As we sipped chamomile tea in the air-conditioned conference room, Dr. Takaoka offered a puzzle."The patients affected by River Blindness in Africa and South America show symptoms in their lower body. The patients in Central America show symptoms on their upper body and head."

"Is that because it's a different species of Onchocerca worm?" I guessed.

"No, same worm. But different effect, because different vector," Dr. Takaoka explained. "Each species of black fly has its own preference where to bite."

"And related to human ecology, too!" Dr. Ya'cob chimed in. "If we cover the head, they go for the feet. Everything related -- One Health!"
A black fly emerges from its pupa.
Photo credit: Zubaidah Ya'cob.
Pupa and newly emerged fly.
Photo credit: Zubaidah Ya'cob.

Next, Dr. Ya'cob hopes to look for a wider variety of hosts and vectors. The possibilities become dizzying, but she wouldn't have it any other way.

"Wild boar and black flies are obvious suspects, but the worm could also be carried in rodents or birds," Dr. Ya'cob explained. "It could be vectored by a different Dipterid, like sand flies or mosquitoes. And there could even be different types of Filarioid roundworms here! Diversity-lah!"

I couldn't help but laugh. In Malaysian English, "lah" is added to any word to give it emphasis or personality. It's my favorite Malaysian saying, and it can be used to mean almost anything. For example, "What lah you?!" expresses utter disbelief, while "sorry-lah" is a typical apology. Another gem is self-explanatory: "Why you so like that lah?" I can think of no better way to sum up One Health in Malaysia than that: Diversity-lah!

Thank you to Dr. Ya'cob and Dr. Takaoka for the wonderful welcome!