Do stray dogs raise risk for human infections of a skin burrowing flea in Kenya?
Are dogs associated with infections by a skin burrowing flea in Kenya? Masanobu Ono and I with Kensuke Goto, Satoshi Kaneko, mwatasa Changoma just published a paper on #tungiasis in the journal Tropical Medicine and Health.
Most people haven’t heard of tungiasis, an ectopic skin disease caused by the skin burrowing parasite, T. pentrans. It causes itching, pain, is associated with serious secondary bacterial infections, gangrene, social exclusion and debilitation. It primarily afflicts the very young and very old and is found almost exclusively in the poorest parts of the poorest parts of the world. It fits the classic definition of a neglected tropical disease.
We explored associations of wildlife and domesticated animals with household level tungiasis in Kenya using a two stage complex sampling based survey in an area adjacent to a wildlife preserve.
Tungiasis is a ectopic skin disease caused by some species of fleas in the Tunga genus, most notably T. penetrans. The disease afflicts poor and marginalized communities in developing countries. Transmission of tungiasis comprises a complex web of factors including domesticated animals and wildlife. This research explores animal and environmental risk factors for tungiasis in an area adjacent to a wildlife reserve in Kwale, Kenya.
A two-stage complex sampling strategy was used. Households were selected from three areas in and around Kwale Town, Kenya, an area close to the Kenyan Coast. Households were listed as positive if at least one member had tungiasis. Each household was administered a questionnaire regarding tungiasis behaviors, domesticated animal assets, and wild animal species that frequent the peridomiciliary area. Associations of household tungiasis were tests with household and environmental variables using regression methods.
The study included 319 households. Of these, 41 (12.85%) were found to have at least one person who had signs of tungiasis. There were 295 (92.48%) households that possessed at least one species of domesticated animal. It was reported that wildlife regularly come into the vicinity of the home 90.59% of households. Presence of dogs around the home (OR 3.85; 95% CI 1.84; 8.11) and proximity to the park were associated with increased risk for tungiasis infestation in humans in a multivariate regression model.
Human tungiasis is a complex disease associated with domesticated and wild animals. Canines in particular appear to be important determinants of household level risk.
New chapter from myself in a Springer volume: “Access to Health Care in Sub-Saharan Africa: Challenges in a Changing Health Landscape in a Context of Development”
I wrote a chapter for “Health in Ecological Perspectives in the Anthropocene” edited by Watanabe Toru and Watanabe Chiho. I have no idea if they are related. Either way, my chapter “Access to Health Care in Sub-Saharan Africa: Challenges in a Changing Health Landscape in a Context of Development” occupies pages 95-106 in the volume.
Check it out, you can buy the book through Amazon for a cool $109, or just my chapter through the Springer site for $29 or you can simply write me and I’ll give you a synopsis.
Here’s the abstract for the book:
This book focuses on the emerging health issues due to climate change, particularly emphasizing the situation in developing countries. Thanks to recent development in the areas of remote sensing, GIS technology, and downscale modeling of climate, it has now become possible to depict and predict the relationship between environmental factors and health-related event data with a meaningful spatial and temporal scale. The chapters address new aspects of environment-health relationship relevant to this smaller scale analyses, including how considering people’s mobility changes the exposure profile to certain environmental factors, how considering behavioral characteristics is important in predicting diarrhea risks after urban flood, and how small-scale land use patterns will affect the risk of infection by certain parasites, and subtle topography of the land profile. Through the combination of reviews and case studies, the reader would be able to learn how the issues of health and climate/social changes can be addressed using available technology and datasets.
The post-2015 UN agenda has just put forward, and tremendous efforts have been started to develop and establish appropriate indicators to achieve the SDG goals. This book will also serve as a useful guide for creating such an indicator associated with health and planning, in line with the Ecohealth concept, the major tone of this book. With the increasing and pressing needs for adaptation to climate change, as well as societal change, this would be a very timely publication in this trans-disciplinary field.
A visit to the local witchdoctor: treating snakebites in Kwale, Kenya
Humans have had to deal with the threat of snakebites as long as humans have existed. While deaths from snakebites are rare, the outcomes are so severe and the nature of the animal so mysterious, that humans have developed all sorts of ways of dealing with them.
Witchdoctors, or Mganga as they are known in East Africa, are the first line for snakebite treatment here. The Waganga are fairly useless for treating many serious health issues, but they have carved out a niche for themselves for a few public health problems.
Our survey in Western Kenya confirms that nearly 100% of people who have been bitten by a snake visit the Mganga, regardless of whether they visit a formal health facility or not.
I went and sat down with an established Mganga here in Kwale and he was gracious enough to answer all of my questions openly and (mostly) honestly.
Hello, thank you for taking the time to speak with me today. Is English OK?
No, my English is not very good. Can we do this through a translator?
Of course. So, what happens when a patient comes in for treatment for a snakebite?
When the patient comes in, I first apply the “njiwe na njoka” (lit: snake stone). The stone sucks all the poison out of the wound. When you put it on the bite, it will stick. When the stone has absorbed all the poison, it will fall off.
What do you mean? Like it just sticks to the flesh without tying it?
Yes, if there is poison, the stone will stick to the body. When all the poison is gone, the stone will fall off. After it is done, I take the stone and wash it with milk several times and then use it again for the next patient.
What is the snake stone? Is it like a rock? I’ve seen people use charcoal in the villages. They tie it to the wound, it doesn’t appear to stick on its own.
No, this is different. This is a stone from the snake. The stone is in the skull of the snake, like that of a fish.
(Note: I did not know this, but some species of snakes have otoliths, like most fish. Snakes (and fish) are deaf in the traditional sense. The otolith is a piece of calcium which grows as the animal ages and sit on top of a bed of nerves. When there are vibrations, the otolith vibrates, stimulating the nerve bed so that the animal can “hear” motion around it. Not all snakes have otoliths but some species of burrowing snakes do.)
Where do you get the stone? Can you just buy it in the market?
The snake stones come from the Maasai, from big snakes in Maasai land. My teacher travels to Maasai land to get them and brings them back.
If the wound is fresh, I apply the stone. However, if it has been two or three days since the bite, I can’t use the stone anymore. Then I have to use a special medicine made from herbs and crushed snake heads. I mix it all together, then crush it into a powder and keep in a gourd.
When the patient comes in, I use a new razor blade to make small scratches on the wound. Then I rub the powder in it and bandage the wound. The wound will try to heal over time, so you have to make the scratches to be able to apply the powder.
Do you use the razor blade again?
No, I always use a new blade. (He was emphatic on this point.)
What is the powder made from?
Snakeheads. When we kill a snake, we keep the heads to make the powder. We mix it with roots, bark and leaves from special plants from deep in the forest. My teacher is a security guard in one of the forests and can get them when he can find them.
Wait, so your teacher is a forest ranger? Can’t he get by being an Mganga?
Yes. He is a forest ranger.
So he took the job so that he can get the plants from the forest whenever he needs them.
OK, so how many bites do you see per month?
It depends, some months I get more than others but mostly one every three months or so.
Do you refer them to the health facility for formal treatment?
Yes, I do. I treat them, then they go to the facility, then they come back to me. (I’m suspicious on this point, though the Mganga in question appears more together than most.)
Is there a religious component to this?
Well, there are two kinds of bites, those where the snake just bites and there is no witchcraft and those where someone has used magic to send the snake to bite you.
How do you know the difference?
If the bite heals quickly, there is no witchcraft. But if the bite is treated and does not improve then there is definitely witchcraft involved. At that time, I have to use powerful magic to get rid of the curse.
What do you do?
I send the snake back to the person who applied the curse. When we hear that someone nearby has been bitten, we know who applied the curse.
(Note: this is not uncommon. Witchcraft is often associated with hatred and revenge but the person applying the curse risks becoming cursed themselves. It is possible that snakebites are seen as a never ending battle of malevolent spiritual forces. What this does is sow distrust among people, even families and the Mganga is seen as the only cure. The result is that the Mganga are never without work.)
How did you learn this craft?
I was sick for a long time with stomach and head problems. I went to the hospital and it never got better so then I went to an Mganga. I improved. The Mganga suggested that I become on and I started training under him.
Thank you very much for your time.
Infectious disease transmission dynamics and the ethics of intervention based public health research
I think a lot about ethics and ethical issues. Research in Sub-Saharan Africa presents unique risks for ethical breaches. Given income and power disparities between individuals and foreign researchers and even between individuals and local political leaders the possibility of coercive research is ever present. Pressure to produce can lead to unrealistic assumptions of risks and benefits to very poor individuals. Inadequate knowledge or willful ignorance of local political issues can compromise future research activities, both by international and domestic groups.
Recently, though, an interesting situation came across my desk that included an intersection of ethics and the dynamics of infectious disease transmission.
As everyone knows, not all infectious diseases are the same. Some, like measles, impart full immunity upon exposure, whereas diseases such as malaria impart only partial immunity, requiring repeated exposures to acquire full or adequate immunity to prevent death or serious injury. Moreover, as immunity and immune reactions change over the life course, the time (age) of exposure are sometimes crucial to prevent serious disease. Polio is a great example. Exposure in infancy leads merely to diarrhea, where exposure at older ages can lead to debilitating paralysis.
I was thinking of an population based intervention study which provides some sort of malaria medication to a small population in a holo-endemic area. Given the year round nature of malaria transmission in this area, we would expect that even with a depression in symptomatic and asymptomatic cases, active transmission in the surrounding areas would lead to recrudescence within a very short time. Given the short time frame, we would assume very little interruption in the development of immunity in small children and might even see a short term reduction of childhood mortality. Assuming that this medication presented little or no risk of serious side effects, I believe that there is little reason to assume an ethical breach. A short term reduction in malaria would suggest that the benefits far outweigh the risks.
However, conducting the same study on a very large population in the same area might have very different outcomes. Delivering a malaria medication to, say, an entire county surrounded by other areas of extremely high transmission would indicate that recrudescence is also inevitable but that the time required to return to pre-intervention levels is extended. Infectious disease transmission requires a chain of hosts. The longer that chain, the longer it will take for new hosts to become newly infected.
Theoretically, this could delay infections in small children and it is theoretically possible that we might see a spike in childhood mortality, since the timing of initial malaria infection and frequency of infections are crucial to preventing the worst outcomes.
Of course, I’m not suggesting that people should just get infected to induce immunity, but I am suggesting that a study which seeks to reduce transmission through pharmaceuticals given only intermittently (as opposed to prophylactically) consider all possible implications. Insecticide treated nets (ITNs) provide protection over time and are a form of vector control. A medication given at a single time point merely clears the parasite, but does nothing to prevent bites or kill mosquitoes.
Though I could be overthinking the issue, my worry is that ethical approvals approach the issue of mass distributions of pharmaceuticals as a one size fits all issue without taking other factors such as population size and acquired immunity into account. Malaria, as a complex vector borne disease introduces complexities that, say, measles does not. Researchers, IRBs and ethics board would do well to consider this complexity.