Diagnosis coding for infectious diseases: The gift that keeps on giving
January 14, 2025 | Karla VonEschen, MS, CCDS-O, CPC, CPMA
When I was growing up, my dad used to have a saying when we got the flu as a family, “it’s the gift that keeps on giving.” He was right because once it spreads within a house full of people, it seems to last forever! It’s not just a full house that is impacted by infectious diseases. My dad now resides in memory care, where the norovirus made an appearance and quickly impacted nine residents on his floor, including him. Despite a mask and compulsive handwashing, I was infected right before the holidays. See, the gift that keeps on giving.
All joking aside, infectious diseases like the norovirus are nasty and nothing to mess with. According to The Centers for Disease Control, there were 91 outbreaks of norovirus the week of December 5, 2024. This is a 32% increase from the last week of November and the highest recorded outbreak during this same period in the previous decade. The Midwest and Southern parts of the United States have been impacted the most, and the Northeast impacted the least. Minnesota, which is my neck of the woods, has reported more than 40 outbreaks, which is twice the December average per the Minnesota Department of Health. This is why complete physician documentation and correct medical coding are critical to tracking infectious diseases.
The norovirus is not the only infectious disease impacting us this time of year. We can also count on the flu and COVID-19 to inundate schools, clinics, hospitals, nursing homes, senior living facilities and job sites. If you don’t catch it at one of these places, you can pick it up while out in public shopping (stay clear of the adult or child openly sneezing and coughing!). Copious amounts of vitamin C, vitamin D, Zinc, Elderberry, and the little bottles of organic juice shots will not save you.
Coding for infectious diseases does not have to be complicated. Since many of my previous blogs have centered around the ICD-11 coding system, I’ll include a comparison with ICD-10-CM. Here are some of the more common infections:
| Infectious disease | ICD-10-CM | ICD-11 |
| Gastroenteritis due to Norovirus | A08.11 (Acute gastroenteropathy due to Norwalk agent) | 1A23 (Enteritis due to Norovirus) |
| Influenza type A, subtype H1N1 | J10.1 (Influenza due to other identified influenza virus with other respiratory manifestations) | XN297 (Influenza A H1N1 virus) |
| Influenza with left otitis media | J11.83 (Influenza due to unidentified influenza virus with otitis media) | 1E32/AB00&XK8G (Influenza, virus not specified with otitis media, left ear) |
| Streptococcus A (strep throat) | B95.0 (Streptococcus, group A, as the cause of diseases classified elsewhere) | 1B51 (Streptococcal pharyngitis) |
There are many ICD-11 codes that are a 1 to 1 match with ICD-10-CM for infectious diseases. It is worth noting that the section for Influenza A Virus in ICD-11 is extensive and includes 33 codes. Per the Mayo Clinic, the distinct proteins (hemagglutinin and neuraminidase) that make up the virus contribute to the different strains we see today. ICD-10-CM does not contain this level of granular information.
As we start a new year remember that medical coding is your secret weapon against infectious diseases. Accurate coding leads to better treatment, keeping you one step ahead and healthy!
Karla VonEschen, MS, CCDS-O, CPC, CPMA, is a clinical analyst at Solventum.
