Environmental and Cultural Shifts are Changing the Way Diseases Can Spread

A recent homegrown malaria case in Maryland has public health experts discussing how infectious disease migration could begin to change. 

The U.S. typically sees about 2,000–2,500 malaria cases every year that are linked to travel by individuals in the U.S. to malaria-endemic areas. Two decades have passed since the U.S. recorded a homegrown malaria case, but, according to a recent Johns Hopkins article from the Bloomberg School of Public Health, nine domestically-transmitted cases have been detected this year. Seven of these cases were recorded in Florida, and one each in Texas and Maryland. While catching malaria in the U.S. is still highly unlikely, experts say the re-emergence and migration of the virus to previously inhospitable environments is cause for concern.

The Anopheles mosquitoes, which are able to carry and transmit malaria, are present in many regions of the U.S.; however, their ability to transmit the virus is fairly weak because there are so few infected people to feed on. Therefore, travel still played a role but likely by individuals coming into the country from endemic areas. Experts have postulated that the new domestic cases have likely emerged as a result of visitors coming in who were infected. In this scenario, the local Anopheles mosquito might have bitten a traveler and then bit someone else who had not recently been out of the country.

The article goes on to discuss that a major outbreak of malaria is currently unlikely because the U.S. does not have the species of mosquito that makes malaria so prevalent in other countries, but conditions are becoming more favorable for transmission. From the article:

Warmer winters are giving the Anopheles mosquitoes an opportunity to start reproducing earlier—meaning that their populations grow to the point where they have a higher probability of biting an infected person who has been to a malaria-endemic area.

The next five years will give a better indication of what the threat level really is for malaria and other diseases, and hosts, that are able to thrive in warmer climates. But the environment is not the only suggested culprit. The recent post-COVID travel surge is also creating an increased opportunity for disease migration. Experts are hopeful this recent emergence of malaria in the U.S. is seen as an opportunity to get ahead of future outbreaks. Bolstering more surveillance of the native Anopheles mosquito populations would be a good start.

This topic is on the minds of public health officials and disease experts across the state, particularly after the malaria case in Maryland that was discovered this past summer. A MACo Winter Conference panel will discuss how climate change is affecting the way communities experience the growth of existing health challenges and new intrusions. The session, “Environmental Rift: When Global Threats Become Local Concerns,” will discuss what changes can be forecasted and how to prepare, on Wednesday, December 6th from 3:00 – 4:00 pm.

Learn more about MACo’s Winter Conference: