Rocky Mountain Spotted Fever (RMSF for short) is one of the most dangerous vector-borne diseases that humans can contract. Yet not a lot of people know how you catch it. Lyme is the heavy-hitter of vector-borne diseases, but there are countless more out there that humans can potentially contract from any given bite of a tick, louse, mite, or flea. Sometimes these can be transmitted simultaneously with Lyme disease, in which case they’re known as co-infections. Sometimes they are contracted singularly and do enough damage on their own. Unfortunately for doctors, many of the initial symptoms of these diseases present the same way. Knowing if you have come into contact with any ticks or fleas recently is key. But is Rocky Mountain Spotted Fever caused by ticks? And if so, what tick causes Rocky Mountain Spotted Fever?
What Is Rocky Mountain Spotted Fever?
RMSF is an acute (as opposed to chronic) infectious disease transmitted to humans through the bite of a previously infected tick. The most crucial thing to know about RMSF is that it can be deadly if it’s not treated with an antibiotic. Before antibiotic intervention, the mortality rate for RMSF was as high as 30%. Since antibiotics have been introduced and become commonplace, that figure has fallen to 3–5%. This makes it the most common fatal tick-borne disease in the U.S., one that still poses significant danger to people all over the country.
Is RMSF A Tick-Borne Illness?
Rocky Mountain Spotted Fever is a result of infection by the rickettsia genus of bacteria, specifically rickettsia rickettsii. The bacteria is spread specifically by three ticks in the United States. The first is the American dog tick, which is found in a large number of states, particularly those on the east side of the country. They are also prolific in California, although rare in most other western states. The second is the Rocky Mountain wood tick, which is where the disease gets its name from. This tick is found in the mountainous states in the west of the country, including Montana, Idaho, Utah, and Wyoming. The third and final tick capable of spreading RMSF is the brown dog tick, which is found all over the country.
Ticks favor grassy and woodland areas, and generally don’t infest a house or even go willingly indoors. People are most likely to encounter them while outdoors, or when their pets come in from being outside. Contrary to popular belief, ticks cannot jump or fly. They hook themselves onto their hosts via a process known as “questing”, which sees the tick balance on the edge of a blade of grass or a piece of bark, with its front legs extended forwards. As an animal or human passes by, the tick will hook onto the skin. Nearly all ticks come into initial contact with humans around their leg area, and then climb upwards, looking for a nook or crevice to feed from. They do not fall out of trees onto people’s heads, and are generally quite immobile. Instead, they are reliant on their potential hosts coming to them.
Tick season is traditionally summer, with the danger zone stretching from May to September. However, some experts have advised that this should be extended from April to October, as global warming is allowing ticks to live longer and migrate further. In general, it is best to be aware of tick behavior and tick bite symptoms all year round, particularly if you live in a place with mild winters.
So is RMSF caused by ticks? Undoubtedly and exclusively so. RMSF is not contagious from person-to-person; you can only catch it from a tick bite, or from contamination of the skin from tick blood or feces. Preventing instances of RMSF comes down to knowing the symptoms and being highly aware of tick habits and habitats. The disease, like many vector-borne illnesses, is easily treatable with antibiotics if it is caught early.
What Are the Symptoms of RMSF?
Like many tick-borne illnesses, the first sign of RMSF is usually the sudden onset of a moderate to high fever. The fever is usually accompanied by a headache, nausea, vomiting, deep muscle aches, and fatigue. A rash may also present in most cases, developing two to four days after the onset of other symptoms. Unlike Lyme, where the rash is a distinctive bullseye pattern, the rash associated with RMSF can vary wildly over the course of the disease.
How is RMSF Diagnosed?
The signs and symptoms of RMSF are very similar to other vector-borne diseases, and other more common illnesses like the flu. The diagnosis of RMSF is based on the patient’s presentation of symptoms along with a number of blood tests to confirm diagnosis. However, if RMSF is suspected, treatment should begin immediately, without waiting for confirmation from lab results.
InfectoLab and BCA-clinic have recently supported the development of a new diagnostic test for Rocky Mountain Spotted Fever, which tests specifically for the presence of rickettsia antigens. By utilizing and capitalizing on the traditional ELISpot blood test, doctors are able to examine antigens created by both the attacking white blood cells and the memory white blood cells. This helps medical professionals understand the relationship the patient has with the disease, what stage they’re at in their fight against it, and what steps need to be taken to combat it effectively. This new test, releasing in January 2020, is designed to test not just for RMSF, but also any kind of rickettsia-related disease.