Monday, October 10, 2011

A little adventure in Adamawa, Cameroon--the mosquito sampling trip 1

It has been two days since I came back from the mosquito sampling trip in the Adamawa Province. It is the 2011 president election day today. I am enjoying the tranquility of this special Sunday in Yaoundé, the capital city of Cameroon, while there came the melodious call to the prayers from a mosque nearby, which reminded me of most days in the Adamawa Province, where Muslim culture dominates.

view of Yaoundé; minaret of a mosque at a distance


"Why did you come to Cameroon for research on mosquitoes?" As I was asked this question often enough, I'd say it all started from a paper I discussed with my advisor Prof. Lacey Knowles three years ago. It simulated situations where a chromosomal structural mutation which reverses the gene orders--inversions--in mosquito populations can promote rapid adaptation to different habitats. The alternative inversions copies from parents might leave no direct fitness cost on the hybrids, but indirectly influencing offspring of them by largely suppressing recombinations around the inversion regions. And if luckily, genes that are crucial to the local adaptation reside in the region, the combination of them can be preserved longer without being shuffled with maladapted alleles from different habitats. I got really interested in the biological and modeling aspects of the evolution of inversions in promoting adaptation and found that the malaria vector in sub-Sahara, Anopheles gambiae was an ideal system to answer my questions, which later on became the major focus on my dissertation proposal. With the aid of grants from the Museum of Zoology and The International Institute as well as the support from Center for Tropical Research in UCLA and the vector genetics lab in UCDavis this year, I'm able to come here for the field work I've been dreamed of for two years.

Although my research interest is very much evolution-based, my field trip felt more like a public health study because of the nature of the species. Anopheles gambie females spend a lot of time inside human houses, hiding at dark spots near beds, on walls, roofs, inside bed nets, either waiting for chance to bite or resting to digest a delicious blood meal. We have to catch blood-fed females for chromosomal karyotyping work, which means we need to enter people's houses in villages. And that is not an easy task.

Sampling sites in the Adamawan Highlands. This region is the transition zone from forest to savanna habitats, harboring high diversity of inversion polymorphism.

En route
As the transition area from forest to savanna ecozones, Adamawa is one of the least developed provinces in Cameroon. Road condition is really poor in the majority of the area so that a jeep or a truck is a must to move around. Starting from Yaoundé, we drove up north through the west province. Paved road stopped right after Foumban, which is near the border of Adamawa. And soon I found myself jolting on the muddy road, moving less than 30km per hour, without knowing that the rest of the journey would be pretty much like this or even worse. Bankim is our first site. Located near the reservoir Bankim, it enjoys the last bit of forest habitat before transition to wet savanna. The reservoir also serves as a good breeding site for mosquito larva.

Bankim

forest nearby

Reservoir Bankim

As a cheaper alternative to paved road, mud road functions well in dry seasons here. However, after one or two months of heavy rains, the road will soon be damaged by over-loaded trucks. Driving through uneven grounds with big rocks and ponds, my driver Elvis had to constantly swerve from one side to another. We can occasionally find Anopheles larva at the temporary ponds at the road side. When we reached the second site, Mbakaou, at the reservoir Mbakaou, our truck had a major repair to fix the brake, the battery and change the bearing of a tire. On the road to the province capital, Ngaoundéré, the LCD of my laptop got broken and the truck went to the garage for repair again. Bad road severely impairs the development. On the whole way of driving through the province, we rarely see any private cars or trucks. We were stuck for about two hours because the truck sank into the mud once. And surprisingly, there were only three trucks waiting behind us. It didn't cause a traffic jam or anything because there were simply no vehicles. Most people prefer to travel by train on the single railway from Ngaoundere to Yaounde. The demand way passes the supply. People were queuing for a standing ticket for hours because seat or sleeper class tickets will be sold out very very quickly. Despite the bad road, the best time en route was when occasionally we met a section of uphill paved road. Overlooking the savanna valley, we felt like we were the only beholder of the vast land. And then there came thatch-roofed huts, cattle herds and people.


on the way from Bankim to Tibati, Mbakaou; Wet savanna habitat


our truck got over-heated after Elvis managed to pull it out of a pile of mud


Reservoir Mbakaou provides a good amount of fish for the local people, as well as Anopheles mosquitoes


Cattle herds; Unlike deers in North America, cows here don't move when seeing vehicles. They only move aside when our truck almost hit them.

Originated in Asia, the humped zebu cattle are everywhere now in Africa. They are the major meat source in Northern Cameroon, especially among Muslims.

North of the Mount Ngaoundere starts the dry savanna. Mbe belongs to the North province and we could feel the increase in the temperature instantly.

Catching mosquitoes
How much communication with local people has to be done before we can get the permission to catch a mosquito inside a village house? I would say a lot. Upon reaching each town, we had to visit the administrative chief of the district, explain our purpose, show the order mission and get his signature. Then we would stop by the health center of the region, notifying the doctor and asking him to help us find local volunteers. Local guides then lead us to different villages in the district and explain to local people about our purpose in either French or local language. Since I don't speak French, these communications are done by my field assistant, Seraphin. Most of the time I had no idea what they said, and Seraphin was used to translate a twenty minute conversation into two sentences. Quite the same experience as that in the movie, "Lost in Translation". When people in the villages got to know exactly what we were going to do, they would be very cooperative. After greeting me with "Bonjour, Madame", they would say "entre, entre" when I intended to take off my shoes if they have floor mats on the ground. People in the villages are nice and honest. They might or might not lock the doors when they leave to work in the farm, but no one will enter the house without the host's permission. It's common to see shops wide open without the shopkeepers, who come back half an hour later. But nothing will be stolen. After finishing the mosquito catch in a village, we sometimes find a big sac of peanuts at the back of our truck as a gift from local people.

We usually do catching twice a day. In mornings from 8-12, we search for mosquitoes inside people's houses, especially bedrooms, using torches. Mosquitoes like dark areas. And they take big advantages on the holes on bed nets. Newly treated bed nets prevent us from catching a single female even using insecticide, but worn bed nets with big holes typically trap 1-20 blood fed mosquitoes. Unfortunately, it was usually old women or men who were using those old bed nets and got bitten terribly. I wish I could speak their local language and say "I'm sorry for the living condition, but thank you for contributing to my study". Mosquitoes are not a quick flyer. We use aspirators to suck them inside a tube when we spot them and blow them into a vial. Typical walls are bricks and mud, rarely concrete. Thatch roof is common. It blocks the sun, so inside it's always cool regardless of the temperature outside. But people are starting to switch to zinc roof for its fire resistance. Mosquitoes love hanging on the thatch roofs. Those that are caught in over-heated zinc houses are usually more fragile. Painted walls ease our search because otherwise their dark body hides well on mud walls.


Seraphin took out tools and gave them to local volunteers

Culex and Anopheles are the two genera that would be commonly found inside houses. Anopheles, however, prefer rural areas much more. The species I'm interested in, An.gambiae, dominates the catch in most sites except for Bankim. At the end of rainy season there, An. funestus is more common. Both of them are notorious severe malaria vectors. Mosquitoes caught in the morning would be reared in vials and fed sugar water to make sure that they digest the blood properly and develop big ovaries.

a good catch

In the afternoon, we do spray catching by directly killing mosquitoes using insecticide and let them fall on white sheets spread on the ground because that's the time when most of the female are half-gravid (i.e., blood is half digested and ovaries have accumulated a lot of eggs). We then kill the morning batch and dissect ovaries out. That can last forever depending on the quantity we catch. We celebrated a good catch with a good meal late in the evening. If it was a bad one, obviously we would have more time eating and drinking!


Dr. Atangana adjusting the microscope for dissection.

Sadou, the best mosquito catcher from the whole trip. He can literally see mosquitoes that I would otherwise never notice.


Life in the villages
Work is highly divided between men and women here. Men go to farms, rear cattle, ride motorcycle taxis, or sit together drinking Sha-y (a kind of sweet herbal tea) for the whole day. Women prepare food, take care of kids, wash clothes and give birth. Violation of the common division of work is considered bad. Usually, when we visit people's houses in the morning, there are only women, pre-school kids and old people. Polygamy is prevalent here. As explained by Seraphin and a local volunteer, Sadou, it is partly because girls over number boys and it's usually difficult for a girl to find a reliable husband. Sadou, a typical Muslim living near Ngaoundere, has two wives in the villages and one in the city. He's only 35 and already has eight kids. He said he should have another wife and at least another two kids. Interestingly, he got a chance to get a fourth wife in Mbe. One afternoon, we sprayed a house and caught a lot of blood-fed mosquitoes. The old woman was so grateful for our work as she thought she'd have peaceful sleep for three weeks. She told Sadou she's willing to give her daughter to him. When I heard Seraphin's translation, they saw my mouth wide open and laughed, saying that that's how people behave here, that's how people regard marriage here. The whole thing is about finding a hard-working guy with means or finding a well-behaved girl who can give birth.


a woman carrying stuff on her head, with a child on her back and probably pregnant


A typical bedroom


a lot of kids have huge tummies. I don't know if that was because of schistosoma in the pond.

Despite the poor living conditions, people are content with life here. It's hard to see people with miserable expressions. There is no electricity or water in most villages. They still lift water from wells, use bush light in the night and firewood for cooking. As a good habit of most tropical countries, they take baths every day at least once using collected rain or well water. Despite the muddy road, they still wash their motorcycles everyday, with a bucket of water. The town of Mbe only has three and half hours of electricity: 6:30-10pm. Nevertheless, Cameroonians cannot live without bars. People continue to drink in the darkness without lights or music in bars.

women selling peanuts

two grades in a single class

Children selling water and food to passengers

moto taxi drivers

I ate local food and drank local boisson for the whole journey. Although I was concerned about the cleanliness, especially about eating with hands, I didn't get diarrhea even once. I guess the fact that I grew up in China gave me a pretty strong stomach. Although the variety, taste and quantity of the food here correlates exactly with the economic status of the place, I think most of the food here is super healthy and organic. Because crops are all naturally farmed with less chemicals added. cattle eat fresh grass and walk long distances every day. I'm wondering how long can this natural way of farming last? When will cattle raising factories start to show up?

a typical meal in Muslim region: tomato soup with beef stew and a huge pile of rice

a woman cutting cassava

a typical Cameroonian meal: Foufou (maize flour made buns), Njamo Njamo (a leafy veggie) and beef stew

Then I sometimes wish the road would never be paved and industries will never come to destroy the beautiful land. But I know that's a too selfish idea. And I know their life has already been permanently influenced by manufactured goods. The most obvious example is the garbage. No recycling, no waste management whatsoever. You'll find piles of trash at a corner here or there in villages or towns. Organic matters go away very quickly, so only plastic bags, bottles, batteries lie there, probably forever. I wish these villages would never become as trashy as some of the Chinese villages. Sustainable development, that's possible, right?

smart usage of the roof


I'm looking forward to my sampling in the west province soon. Wait for my blog about new experience in three weeks!