California officials have reported a rare case of a tick-borne illness affecting a local resident. This incident marks the fourth known occurrence of the disease, caused by the bacterium *Rickettsia lanei*, globally. The diagnosis was confirmed by the California Department of Public Health (CDPH), which stated that the individual likely contracted the bacteria in Northern California.
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The case was diagnosed in April, with the affected person requiring hospitalisation for treatment. Fortunately, they have since been released, although specific details regarding their symptoms have not been disclosed. The CDPH has not provided additional information on the case at this time.
*Rickettsia lanei* was first identified in 2018, discovered in rabbit ticks located in Sonoma County. Although it was initially believed to only affect animals, 2023 saw a significant breakthrough when researchers established that humans could also be infected. This finding emerged when a man presented at a Bay Area emergency room with symptoms resembling those of a fever. After several days of deteriorating health, during which he experienced seizures and low oxygen levels, doctors suspected he might be suffering from a rickettsial disease or a related condition. He was treated with doxycycline and ultimately spent 22 days in hospital before his release.
Anne Kjemtrup, a research scientist and veterinarian at the CDPH, indicated the potential severity of the *Rickettsia lanei* infection, likening it to Rocky Mountain spotted fever, another tick-borne illness. Both diseases can result in serious symptoms such as headaches, fever, rashes, nausea, and abdominal pain. Kjemtrup pointed out that Rocky Mountain spotted fever has a notable fatality rate of 5% to 10% in the United States, rendering it one of the most dangerous vector-borne diseases in the Americas.
Various sightings of infected ticks have been reported along the California coast this year, including in Contra Costa County—the location of California’s first human case connected to *Rickettsia lanei*. Kjemtrup emphasised the need for ongoing research to better understand the transmission of this bacteria and its effects on human health, stating, “There’s so much we don’t know.”
In light of these rare but concerning cases, public health officials have issued warnings regarding the risk of tick-borne illnesses, especially with summer approaching. The Centers for Disease Control and Prevention (CDC) has provided guidance for individuals to remain vigilant while in tick-prone environments, such as grassy, bushy, or wooded areas.
For those engaging in outdoor activities, the CDC recommends adhering to several precautions: staying in the centre of hiking trails to minimise contact with vegetation where ticks may reside and applying EPA-registered insect repellents after sunscreen when spending time outdoors. These measures are crucial in reducing the risk of exposure to ticks and the diseases they may transmit.
As research continues into the behaviours and impacts of *Rickettsia lanei*, officials and health experts will strive to keep the public informed whilst promoting practices that can help prevent further infections. Public awareness is essential to ensuring that individuals can enjoy outdoor activities while minimising their risk of contracting tick-borne illnesses.