Malaria in the United States

I just finished watching the BBC miniseries “Martin Chuzzlewit” (1994), which involves a trip to a frontier town in America where everyone is dying of malaria. It occurred to me that malaria used to be as serious a problem in parts of the United States as it is now in many other parts of the world; a recent show about parasites (on one of the educational cable channels; Discovery Health maybe?) quoted the figure that 1/2 of all people who have ever been born, died of malaria. Mortality in infected areas seems to be about 1/3, with a significant portion of the survivors suffering periodic relapses.

But how was it conquered in the US? One never hears of people catching malaria here anymore.

A little research yielded the information that the Tennessee Valley Authority included a large anti-malarial program, which virtually eliminated the disease in the US. But this doesn’t answer my question–how exactly was it done? There are still plenty of mosquitoes, they just don’t happen to carry the parasite. So… how?

Your post brings up a related question I’ve often wondered about – how hard would it be, exactly, for an individual or group of individuals with a grudge against the US to re-introduce malaria or yellow fever into the US? Certainly, here in Houston, if malaria ever became endemic again, we would have major problems. Is it only carried by certain species of mosquitos?

If you know what areas tend to have lots of cases with malaria, you can just spray the heck out of the area with insecticides to get rid of those mosquitoes. It’s not like the mosquitoes with malaria are going to migrate.

You would need to get a lot of mosquitoes, all of whom you know are carriers of malaria or yellow fever and then get them to mutliply and then have them go around and sting people and get them sick.

Or you can just build a bomb.

We are wicked good at erradicating mosquitos if we put our minds to it. The first time I visited Hawaii, I got 57 bites on my legs. Shortly after that, they had a couple cases of West Nile virus and started a mosquito eradication campaign. They were doing stuff like flying helicopters slowly up and down looking in people’s yards and making sure nobody had any standing water anywhere. When I went back the next year, I didn’t get a single bite.

I once went to a talk on weird diseases that was given by some expert from the CDC–worked in a Level 4 lab, spent time in Africa trying to find the animal reservoir of Ebola–the works. He said that what killed malaria in the U.S. was TV and air conditioning. Instead of spending summer evenings sitting on their front porch, trying to get a breeze, gabbing with the neighbors and getting bitten, people took to sitting in their nice, cool, totally enclosed parlor, watching TV.

Also, malaria is pretty treatable nowdays in a first-world medical environment. Of 1337 cases in the US in 2002 (almost all aquired in other countries) there have been 8 deaths. Some of these cases have led to local outbreaks, but nothing widespread. We have some pretty powerful prophylactics that can help prevent the disease from forming in bitten indivduals, a good understanding of how to control mosquitos and exposure to them (not to mention climate controlled environments that make it possible to do so) and a fast news media and responsive goverment to act instantly to contain outbreaks.

We have a vaccine for yellow fever, plus all travellers in to yellow fever zones must show proof of vaccination. Like malaria, it is not exceptionally deadly when first-world medical care is possible. It’s one of the most tightly controlled diseases in the world, and it’s highly unlikely to become a problem here.

My mother-in-law contracted malaria in southern Iowa sometime in the early 40s.

I was surprised to hear from my grandmother, who was born in New York City in 1900, that she had had malaria as a child. I had not realized how far north it uses to extend.

Googling a few sites, I was also interested to learn that the efforts to control malaria in Panama during the construction of the Panama Canal seem to have preceded the major campaigns in the US.

This site has some of the history.

While it also is not too explicit about the US campaign, I would imagine it would have been similar to the successful campaign in Panama. First of all, not all mosquitoes carry malaria, only Anopheles, which likes to breed in small stagnant pools in urban areas.

The campaign in Panama included:

  1. Getting rid of old cans, pots, bottles, tires, and other trash where water accumulated, and also cisterns in houses.

  2. Getting rid of pools of standing water and improving drainage of ditches.

  3. Spraying pools of water that were too large to drain with insecticide, or covering the surface with a thin film of oil to suffocate mosquito larvae.

  4. Installing screens in windows, or promoting the use of mosquito nets.

  5. Treatment of infected people with quinine.

Most forms of malaria that cause disease in humans only infect humans; that is, there is no reservoir in wild animals. Once you have broken the chain of transmission from human to mosquito to human, malaria is gone and won’t reappear in an area unless it is reintroduced by infected humans. If it does reappear, an intense eradication campaign can eliminate it.

Malaria is now gone from most of Panama. It is only a danger in remoter areas of the Darién and Bocas del Toro.

Nice story, but that can’t really be true. Malaria was considered to have been eradicated in the US by 1951, when not that many people had TVs and air conditioning was still considered something of a luxury.

By the way, when I first came to Panama in the late 1970s, and up until a just before the US left in 1999, a fumigation truck used to drive around all the neighborhoods in the Canal Area just after dark spraying clouds of insecticide. I think it was pyrethrum by that time, but earlier it was probably DDT. The smell of pyrethrum still makes me nostalgic for the old Zone.

Well, he sounded believable. :o

I thought it was DDT that eliminated malaria in the USA. Are not there activists wanting DDT to be re-introduced so that it can be used in the parts of the world where Malaria exists ?

I think a combination of things caused malaria to die out: better availability of diagnosis and treatment meant that fewer infectious people were available for mosquitoes to pick up a load of sporozoites from; electric lights, fans, and radios as well as window screens in rural areas (think TVA) greatly reduced the opportunities for mosquitoes to infect the uninfected or to pick up those nasty sporozoites; and regular fogging of mosquito-infested residential areas with DDT greatly diminished the mosquito population.

I think the person from the CDC was emphasizing the fact that simple interventions not even intended to prevent disease can have a major impact. In the case of malaria, for example, risk is greatly decreased in travelers in Africa if they stay in air conditioned (or at least screened and ventilated) rooms after dark. By extension, providing rural Africans with a TV and air conditioning probably would have a huge affect on malaria transmission.