In 1854, London saw yet another deadly epidemic of cholera. London was burgeoning under the influence of the Industrial Revolution, but it’s medieval (literally) sewers, trash heaps, gutters, and under-your-house cesspools were overflowing with slaughterhouse offal, grease-rendering run-off, and market animal excrement. The city began dumping it’s unwanted filth into the Thames river which became smelly and dangerous.
Many physicians, scientists, and politicians at the time believed that disease was transmitted by bad air–in particular, air putrefied by rotting matter (called the miasma theory). This wasn’t a totally stupid idea. Scientists of the time could observe fungus spores on their microscopes and could observe the close correlation between coughing and death. They could see the smoggy air out their windows and the filthy streets at their feet. Unfortunately, the cholera outbreaks continued persistently despite treatments of the time.
Dr. John Snow (not that one), had another idea. He theorized that cholera was spread through water tainted with germs (the germ theory). When an extremely bad outbreak of cholera occurred in Soho (127 people died in three days), Dr. Snow with the help of Reverend Whitehead carefully interviewed the patients and the community members. He was able to identify what each of the patients had in common: a water pump. He took samples of the water, but it was inconclusive. He asked the city to take the handle off the pump. They did so and the infection seemed to decline. (In his journals, he is careful to note that the disease was already declining because people had fled when the outbreak occurred, but that taking off the handle did seem to help reduce the infection rate.) He carefully drew a dot map of all those who had died from cholera in the neighborhood and noticed an anomaly which further supported his water-borne theory. None of the employees from the Broad Street brewery got sick. As part of their wages, they were given beer to drink. And the water for the beer is boiled–killing the germ.
And that’s how modern epidemiology was born.
Today, much of the epidemiology work is done by the Center for Disease Control (CDC) and the World Health Organization (WHO). Like Dr. Snow, they monitor disease outbreaks, make recommendations, and respond to emergencies with vaccines or other appropriate care.
In March 2017, the CDC recorded an enormous spike in another disease, like cholera, spread by the fecal-oral transmission route: hepatitis A. Hepatitis A is a viral infection which targets the liver. It is spread by fecal contamination and is completely preventable by good hygiene (washing hands, drinking clean water) and vaccinations. It is most often found in places of crises with developing or destroyed infrastructure. So why was it showing up in San Diego, Salt Lake City, Detroit, and New York City? The Huffington Post reports the CDC’s numbers in this terrific graphic.
In San Fransisco, escalators were being shut down for cleaning. Excrement had piled up in the gears. In San Diego, feces on the sidewalks and streets were being dried and aerosolizing (becoming airborne). It became so bad that San Diego washed it’s streets with bleach and is scheduled to continue to do so every two weeks. Detroit saw a national record (post release of a vaccine) of 837 cases of hepatitis A–bad enough for the state health department to issue a travel warning. I could go on.
If Dr. Snow’s observations have taught us anything, I think it’s taught us to look at outbreaks as warning sign of a city in crisis. Sick cities make people sick.
In this case, as the Washington Post (and others) posit, the crisis is homelessness. Hepatitis A outbreaks correlate to cities with the highest homelessness and drug-user populations (people who shared needles used to be the highest population of hep A patients in the 90’s but that has now changed). Homelessness is caused by many factors, but many in the Bay Area argue that the rise in housing costs coupled with a decline in public facilities caused this particular issue. Others argue that an increase in spending on public services has attracted homeless persons to these areas. But whatever the case, it remains, that the streets are unhealthy.
Additionally, the outbreaks have been hard to stem because the vaccine for hep A is a two-part dose administered several days apart. It can be difficult for health workers to follow up with homeless patients to get their second shot. This allowed the hep A outbreak–which would normally be contained by herd immunity–to get large enough to enter the broader population (only briefly, and to no great harm thanks to quick-acting responders).
On the other hand, the hep A outbreaks are (at least in San Diego) causing vulnerable homeless populations to become even more vulnerable as the city is taking a more proactive stance on arresting homeless people. The justification is two-fold: a) they need to move so that the city can wash the sidewalks and b) they are disproportionately falling ill due to unsanitary conditions. It might be better to remove them to a clean area for prevention and treatment. In the meantime, the homeless want to know what will be done with them and their possessions now that they have been moved.
Fortunately, there is some good news. As of April 2018, the CDC reports the following:
With the slowdown in reported hepatitis A cases across California, CDPH has demobilized the outbreak response and continues to monitor reported hepatitis A cases statewide.
There is similar news from all the infected cities. Thanks to a history of epidemiology and the quick action of health-care professionals, we have quelled hepatitis A in our cities. For now.
Dr. John Snow’s research into cholera helped to inform London’s city planners decisions over time. The pump at fault was drawing water three feet from an underground cesspit which had begun to leak. Because of this and other incidents, we know how to keep our water and sewage separated.
What will these modern hep A outbreaks teach us about city planning?
- The Sacremento Bee, Sept 2017: lack of bathrooms linked to hepatitis A outbreak among homeless
- Washington Post, Oct 2017: Hep A attributed to high rents
- San Diego Tribune, Nov 2017: Homeless arrested to help with outbreak
- Pacific Standard, Nov 2017: Opinion. “How San Diego is trying to use a hepatitis outbreak to solve its housing crisis.”
- Wired, Oct 2017: Hep A and Urban Planning
- From PBS: Hep A attributed to homelessness
- Fun maps
- Really great gallery of pics from SFGate