Rédaction Africa Links 24 with Helen Branswell
Published on 2024-02-15 18:05:38
A new report released by the Centers for Disease Control and Prevention (CDC) suggests that Lyme disease cases in the United States rose by 69% in 2022 compared to previous years. However, this significant increase is attributed to a new way of conducting surveillance for the disease, rather than an actual surge in cases.
This change in surveillance methodology was implemented in 2022 to alleviate the reporting burden on states where Lyme disease infections are common. Under the new approach, 15 states that have historically reported about 90% of all Lyme disease cases are now only required to report a case to the CDC if there is a positive blood test result. Conversely, states where the disease is rare must still collect clinical data on each person with a positive Lyme test before reporting it as a case.
Using this revised surveillance approach, 62,551 Lyme disease cases were reported to the CDC in 2022, which is 1.7 times the annual average of 37,118 cases reported during the period between 2017 and 2019. This new method acknowledges that there are many more cases of Lyme disease in the country than are reported to the CDC and aims to reduce the onerous reporting workload of public health departments in high-incidence areas.
Kiersten Kugeler, an epidemiologist in the CDC’s Division of Vector-borne Disease and the first author of the article published in the CDC’s online journal Morbidity and Mortality Weekly Report, explained, “So we’re capturing a bigger piece of that pie. And we’re saving them time.”
Lyme disease is caused by the bacterium Borrelia burgdorferi, which is transmitted to people through the bites of blacklegged ticks prevalent in the Northeastern, mid-Atlantic, and central Midwestern states. Those infected may experience symptoms such as fever, headache, fatigue, and a skin rash resembling a bullseye. While the infection can be treated with antibiotics, if left untreated, some cases can lead to long-term problems by spreading to the joints, heart, and nervous system.
The challenge in capturing the burden of Lyme disease lies in the fact that existing diagnostic tests do not detect the disease in the first weeks after infection, as they detect antibodies that develop over time. Additionally, many people who are infected may not undergo testing and will be diagnosed based on their symptoms and the characteristic rash. Most of these cases remain unreported to public health authorities.
The prior surveillance system required public health departments to gather clinical information from physicians for each positive test to ascertain the diagnosis of current Lyme infection. However, for states with a high number of Lyme cases, this became impractical and unsustainable.
The revised approach was met with increased reporting from specific states. For example, Minnesota reported zero cases in 2020 due to the overwhelming focus on COVID-19 work, but reported 2,685 cases in 2022. Similarly, Massachusetts reported 5,052 cases in 2022, a significant increase from the 144 cases per year average reported between 2017 and 2019.
State Epidemiologist Catherine Brown commented on the change, stating that the new surveillance definition takes into account the varying needs of states in terms of Lyme surveillance, which she called “revolutionary.” Although comparing numbers before and after 2022 under the revised system may not be fruitful, it does provide a clearer picture of Lyme disease, allowing for better tracking of trends across states with a high burden of the disease.
The new surveillance approach represents a more sustainable way to track Lyme disease cases, offering hope for improved public health surveillance and comparison of trends across state borders. The findings from the report signify a step forward in the battle against Lyme disease, providing a more accurate representation of the disease’s prevalence and impact on public health.
