A night in the field with the “mosquito whisperers”

Kochelani (middle) with two community health workers trained in entomological surveillance. Photo: PATH/Kochelani Saili

By Matt Boslego
PATH Communications Assistant

Kochelani Saili and Javan Chanda are entomological surveillance officers with PATH in Zambia, monitoring the behavior, population dynamics, and resistance to insecticides of mosquitoes. Their work has earned them nicknames like the “mosquito hunters” and the “mosquito whisperers” by their colleagues. Kochelani and Javan explain why they chase mosquitoes and how the data they collect can be used to eliminate malaria in this interview.

Kochelani explaining his work to community members in Southern Province, Zambia. Photo: PATH/Kochelani Saili

What does a typical day—or, night—in your entomological surveillance work look like?

KOCHELANI: Well, not all of the methods that we use require us to be out all night, but some do, such as human landing catches and mosquito sampling with backpack aspirators. When we are using these methods, we go to the community the day before to explain our visit so that people are not surprised to see us at 4 AM in the morning. We come back to the village very early in the morning, when the mosquitos that spread malaria are most active. The roads can be difficult, and sometimes we spend several hours traveling across rough terrain. When we arrive, we meet with the local community health workers and visit people’s houses, waking them up to do our collections. They might ask us a few questions, but after some explanation, they are generally very cooperative.

What is involved in a human landing catch? Is it difficult to find someone to volunteer to be bitten?

KOCHELANI: So in human landing catches, as you can tell by the name, we use humans as bait. We ask one volunteer to sit in a house, and another to sit outside to check the different biting rates—indoor versus outdoor—and to monitor when the biting is taking place. We usually work with trained community health workers who understand the importance of this work, and they are always willing to help. There are five total methods we use, and from all of these methods we learn about mosquito density, species composition, resistance to insecticides, seasonality, and behavior.

How will this information support malaria elimination?

JAVAN: Several ways. First, this data will help us plan indoor residual spraying efficiently. We can choose to do more spraying in areas with high mosquito densities, and less in areas with low densities. Once we see the trends, we can also create a resistance management strategy, where insecticides are used in a rotational manner. That way, with time, insecticide susceptibility in mosquitoes will return.  We may be able to make other recommendations as well. For example, we have seen more people being bitten outside than we expected. If the data proves this, we may start recommending that people change their behavior, spending less time outside at night or at least bringing a bed net outside when they sleep.

Clearly this is not an easy job! What is your favorite thing about your work?

KOCHELANI: We’ve been doing this since September. Now, when we arrive in a village people recognize us. Children get excited–they run to announce that the mosquito catchers are here. So it’s great to see that the work is slowly being recognized, and being accepted. For me, it’s heartwarming.

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