New publication: An urban-to-rural continuum of malaria risk: new analytic approaches characterize patterns in Malawi
12 years in the making! Our new paper from partners at the University of Michigan and the #Malawi College of Medicine on new approaches to defining urban and rural environments in the context of malaria risk is now out in #Malaria Journal.
It was the last chapter in my dissertation to be published (all the rest were published when I was still in grad school.)Short version: malaria is complicated and really local. Malaria transmits poorly in urban and environments and well in rural environments. There’s urban like spaces in “rural” areas and rural-like spaces in “urban” areas, demanding a more nuanced view of what those terms really mean.
We know that malaria is a “rural” problem, but not all “rural” spaces are the same. Even in the country, there are “urban like” spaces and in “rural like” spaces even in the largest cities in Sub-Saharan Africa. Could those spaces impact malaria risk? If so, shouldn’t we redefine what we mean by urban vs. rural to inform intervention strategies to better target resources?
Here, we combine GIS and statistical methods with a house to house malaria survey in Malawi to create and test a new composite index of urbanicity and apply that to create a more nuanced risk map.
The urban–rural designation has been an important risk factor in infectious disease epidemiology. Many studies rely on a politically determined dichotomization of rural versus urban spaces, which fails to capture the complex mosaic of infrastructural, social and environmental factors driving risk. Such evaluation is especially important for Plasmodium transmission and malaria disease. To improve targeting of anti-malarial interventions, a continuous composite measure of urbanicity using spatially-referenced data was developed to evaluate household-level malaria risk from a house-to-house survey of children in Malawi.
Children from 7564 households from 8 districts in Malawi were tested for presence of Plasmodium parasites through finger-prick blood sampling and slide microscopy. A survey questionnaire was administered and latitude and longitude coordinates were recorded for each household. Distances from households to features associated with high and low levels of development (health facilities, roads, rivers, lakes) and population density were used to produce a principal component analysis (PCA)-based composite measure for all centroid locations of a fine geo-spatial grid covering Malawi. Regression methods were used to test associations of the urbanicity measure against Plasmodium infection status and to predict parasitaemia risk for all locations in Malawi.
Infection probability declined with increasing urbanicity. The new urbanicity metric was more predictive than either a governmentally defined rural/urban dichotomous variable or a population density variable. One reason for this was that 23% of cells within politically defined rural areas exhibited lower risk, more like those normally associated with “urban” locations.
Its always a thing to celebrate, getting these new papers out. This one covers a topic close to home. After years of doing global health work, I never thought I’d be doing domestic health and even less certain that I’d be covering topics just down the road from me.
Together with partners from Wayne State University (Health Urban Waters), UM-Dearborn and the University of Michigan Ann Arbor, we characterized the state of recurrent flooding in Detroit, MI and explore possible public health impacts. The article appears in the International Journal of Environmental Research in Public Health. This was extremely rewarding work.
Article is open access.
Household flooding has wide ranging social, economic and public health impacts particularly for people in resource poor communities. The determinants and public health outcomes of recurrent home flooding in urban contexts, however, are not well understood. A household survey was used to assess neighborhood and household level determinants of recurrent home flooding in Detroit, MI. Survey activities were conducted from 2012 to 2020. Researchers collected information on past flooding, housing conditions and public health outcomes. Using the locations of homes, a “hot spot” analysis of flooding was performed to find areas of high and low risk. Survey data were linked to environmental and neighborhood data and associations were tested using regression methods. 4803 households participated in the survey. Flooding information was available for 3842 homes. Among these, 2085 (54.26%) reported experiencing pluvial flooding. Rental occupied units were more likely to report flooding than owner occupied homes (Odd ratio (OR) 1.72 [95% Confidence interval (CI) 1.49, 1.98]). Housing conditions such as poor roof quality and cracks in basement walls influenced home flooding risk. Homes located in census tracts with increased percentages of owner occupied units (vs. rentals) had a lower odds of flooding (OR 0.92 [95% (CI) 0.86, 0.98]). Household factors were found the be more predictive of flooding than neighborhood factors in both univariate and multivariate analyses. Flooding and housing conditions associated with home flooding were associated with asthma cases. Recurrent home flooding is far more prevalent than previously thought. Programs that support recovery and which focus on home improvement to prevent flooding, particularly by landlords, might benefit the public health. These results draw awareness and urgency to problems of urban flooding and public health in other areas of the country confronting the compounding challenges of aging infrastructure, disinvestment and climate change.
Is pollen associated with suicide? That’s the question we sought to answer. Pollen related allergic rhinitis is associated with depressive symptoms, discomfort, pain, sleep disruptions, isolation and reduced quality of life in people who have them. Our team, led by UM researcher Dr. Rachel Bergmans, set out to test associations of suicide mortality in Ohio with pollen exposures using data from Ohio’s vital records and a novel prognostic, model based raster of daily pollen counts from Dr. Allison Steiner’s team at UM’s College of Engineering.
We explored associations of suicide with exposure to four types of pollens and the paper can be found here (Open access for 50 days). Suicide is serious. Though the causes of suicide are complex, pollen allergies are associated with depressive symptoms, isolation, pain, discomfort and for some, complete debilitation. #suicide#pollen#epidemiology
Background Seasonal trends in suicide mortality are observed worldwide, potentially aligning with the seasonal release of aeroallergens. However, only a handful of studies have examined whether aeroallergens increase the risk of suicide, with inconclusive results thus far. The goal of this study was to use a time-stratified case-crossover design to test associations of speciated aeroallergens (evergreen, deciduous, grass, and ragweed) with suicide deaths in Ohio, USA (2007–2015).
Methods Residential addresses for 12,646 persons who died by suicide were linked with environmental data at the 4–25 km grid scale including atmospheric aeroallergen concentrations, maximum temperature, sunlight, particulate matter <2.5 μm, and ozone. A case-crossover design was used to examine same-day and 7-day cumulative lag effects on suicide. Analyses were stratified by age group, gender, and educational level.
Results In general, associations were null between aeroallergens and suicide. Stratified analyses revealed a relationship between grass pollen and same-day suicide for women (OR = 3.84; 95% CI = 1.44, 10.22) and those with a high school degree or less (OR = 2.03; 95% CI = 1.18, 3.49).
Conclusions While aeroallergens were generally not significantly related to suicide in this sample, these findings provide suggestive evidence for an acute relationship of grass pollen with suicide for women and those with lower education levels. Further research is warranted to determine whether susceptibility to speciated aeroallergens may be driven by underlying biological mechanisms or variation in exposure levels.
We published a new paper on Covid-19 and ER visits for suicide attempts/self harm incidents in Epidemiology and Community Health today
Rachel Bergmans, an epidemiologist from the University of Michigan Institute for Social Research (and soon the University of Michigan Medical School) and I recently wrote a paper on the impact of Covid-19 and Covid-19 policy in the state of Michigan on emergency room visits for suicide and self harm incidents.
I am happy to say that it appeared today in Epidemiology and Community Health and encourage everyone to read it here.
Many worried that Covid-19 and the resulting “lockdown” measures would result in rapid increases in suicide attempts due to increased unemployment and social isolation. We did not find an increase in ER visits for self harm and suicide attempts at the University of Michigan Hospital in Ann Arbor, MI. In fact, we found a decline in visits that continued into the winter.
Though it is impossible to know (from this data) what the actual reasons for this decline were, these results suggest that the Covid-19 crisis might not be comparable to previous economic downturns. It might suggest that efforts to financially support those left out of work by the shutdown might mitigate the worst effects of an rapid unemployment.
I am very proud of this work, here is the abstract:
Objective Determine the early impact of the COVID-19 pandemic on emergency department (ED) encounters for suicide attempt and intentional self-harm at a regional tertiary academic medical centre in Washtenaw County, Michigan, which is one of the wealthier and more diverse counties in the state.
Methods Interrupted time series analysis of daily ED encounters from October 2015 through October 2020 for suicide attempt and intentional self-harm (subject n=3002; 62% female; 78% Caucasian) using an autoregressive integrated moving average modelling approach.
Results There were 39.9% (95% CI 22.9% to 53.1%) fewer ED encounters for suicide attempt and intentional self-harm during the first 12 weeks of the COVID-19 pandemic (ie, on or after 10 March 2020, when the first cases of COVID-19 were identified in Michigan).
Conclusions Fewer individuals sought emergency care for suicide-related behaviour during the earlier phase of the COVID-19 pandemic than expected when compared to prior years. This suggests initial outbreaks of COVID-19 and state of emergency executive orders did not increase suicide-related behaviour in the short term. More work is needed to determine long-term impacts of the COVID-19 pandemic on suicide-related behaviour and whether there are high-risk groups.
Currently, I am a part of a project looking at climate change impacts on the distribution of tree and grass pollens in the US and associations with allergy and asthma related emergency room visits
As part of that, we are collecting baseline data on symptomatic profiles of patients who are sensitive to tree and grass pollens and are currently undergoing immunotherapy in local clinics.
Our survey is two fold, the first a baseline survey of types of demographics, types of allergies, seasonal sensitivities, general symptoms and lifestyle impacts, the second a three week survey of sleep quality and allergy and asthma related events.
We hope to gather data to see how the ragweed season might impact general health and well being using a coarse raster of predicted pollen distribution.
The survey is being conducted at the University of Michigan Allergy Specialty Clinic and Food Allergy Clinic at Domino’s Farms and will include approximately 50 people.
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.
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.
We just spent the day driving around Kwale looking for snakes, and/or people who had been bitten by snakes. As the last post showed, snakebites are a persistent problem along the Kenyan Coast, with more then 5% of the households we survey indicating that at least one person in the household had been bitten in the past two years.
It wasn’t difficult to find them.
Snakes are universally feared all over Africa and the associations with witchcraft make it a common topic of discussion. Everyone knows someone who has been bitten. They often know all the details, including where it happened and what occurred following the bite. It’s never a happy story.
We went deep into Kinango, an extremely rural area west of Kwale Town and found a friendly lady who seemed to know everything about everyone. She was incredibly jolly, pulled out some plastic chairs for us to sit under and cracked jokes the whole time. I even got to copy her collection of Sangeya music which she had recorded on her phone (another post but you can hear some of it here) at some local music festivals. In total I got more than five hours of live Sengeya and Chilewa music. In the music world, these would be called “field recordings.” Here, this is just music she cooks and cleans to.
Switching back and forth between snakes and Sengenya (in Africa it seems to be possible to have multiple conversations at once), she told us about a kid who had been bitten two days previous. She even told us where to find her, so off we went.
The child was collecting firewood around a mango tree near her home, when she was suddenly bitten by a large green snake, not once but three times on the foot. The snake bit once skated away, decided it wasn’t enough and came back and bit her twice more.
Ants had moved into the dead tree and hollowed out the area underneath. Presumably, the snake moved in previously and came out to warm up during the day.
The mother thankfully took the child immediately to Kinango Hospital and treated was administered. The child was given a three day course of antivenom injections and charcoal was wrapped around the wounds to absorb any venomous discharge. Though the child complains of some numbness in the area, it looks as if there won’t be any permanent damage. Thankfully.
We were also told of an old woman who had been bitten more than 20 years ago, and was badly scarred, figured out where she was and off we went again.
As we pulled up a friendly young lady came out to greet us, and showed us the way to the house out back. In the distance, we could see an old lady walking with a limp. Otherwise, she was completely fit and seemed to be cutting her own firewood with a panga.
She brought us out some chairs and sat down to chat. In 1992, she had been out back collecting firewood (a pattern) and was bitten on the foot by puff adder, one of the deadliest snakes in the world. She was bitten on the foot, and became immobile for nearly a week. A series of witch doctors were brought in, who administered charcoal rubbed into small cuts in the skin.
Necrosis set in, and watery blood erupted out of the wound site. A large number of maggots appeared. Finally, someone had the good sense to take her to the hospital, where she spent an entire year.
The details were unclear, but it appeared that the gangrene was so severe that multiple infections were presents. They likely had her on intravenous antibiotics for an extended amount of time. Despite this, the foot did not heal. Some Christian missionaries came, and convinced her to convert to Christianity, which, she claimed, improved her condition. This is likely coincidental.
The doctors suggested a skin graft to improve the foot, but she refused. Necrosis was so deep that it permeated the bone and the foot is permanently curved as a result. The leg still shows sign of swelling even more than 24 years after the bite. In most cases, they probably would have simply amputated.
The lady was born in 1948, bore ten children, one of which was born just as she was bitten. She was unable to breast feed or care for the child. Regardless, the daughter has two children of her own now.
Snakebites are bad news. In this woman’s case, the disregard for proper medical care simply made a bad situation worse. She is truly lucky to be alive. If she had died, it is doubtful that the Mgangas would have admitted any responsibility.