What Is Rickettsia?
Rickettsial diseases or rickettsioses are infections caused by various bacteria belonging to the genus Rickettsia. These bacteria are transmitted through the bites of certain hard-bodied ticks and some other arthropods. Rickettsial diseases are not to be confused with rickets, which is a condition affecting the bones and resulting from vitamin D deficiency.
The infections caused by Rickettsia bacteria have traditionally been classified into two groups: spotted fever and typhus. However, they’re sometimes divided into further categories. Either way, all groups include species of pathogens that can infect humans. Although Rickettsia bacteria can be found worldwide, the most common rickettsial illnesses are normally contracted in Africa and Asia.
Lyme disease is also transmitted to humans by ticks. It’s the most common tick-borne illness in the northern hemisphere. However, Lyme isn’t a rickettsial disease, since it’s caused by a bacterium of a different genus: Borrelia burgdorferi.
However, the same tick that carries Rickettsia bacteria might also be infected with Borrelia burgdorferi. Therefore, it’s possible to contract both illnesses via one tick bite. Therefore, the answer to question ‘is Rickettsia a Lyme co-infection?’ is that yes – rickettsiosis can be a potential co-infection of Lyme disease.
What Are The Symptoms of Rickettsia Diseases?
Some of the most common rickettsial diseases are Rocky Mountain spotted fever, anaplasmosis, ehrlichiosis and typhus. All of these are generally difficult to diagnose. Some of them rarely cause symptoms, and most of them only cause moderate illness even when symptomatic. However, certain forms of spotted fever and typhus may be fatal if left unrecognised and untreated. The sooner these illnesses are diagnosed, the easier they are to treat using antibiotics.
The clinical presentation of rickettsial diseases varies greatly. Even infections caused by the same species of bacteria may produce different symptoms in different patients. Nonetheless, the most common symptoms include fever, headache, fatigue, malaise, nausea, vomiting, rashes and eschar (a piece of dry and dark dead skin at the site of the bite). These tend to develop within two weeks after the bacteria have entered the body.
African tick bite fever is one of the mildest forms of rickettsiosis. Patients usually present with fever, headache, muscle pain and an eschar shortly after contracting the disease during a visit to southern Africa.
Mediterranean spotted fever is a serious and potentially life-threatening illness. It’s prevalent in the Mediterranean region, including northern Africa. In addition to fever, rashes and an eschar are typical signs of the illness.
Patients with Rocky Mountain spotted fever often experience fever, headache, nausea, and stomach pain. A rash at the site of the bite is also commonly seen, but eschars aren’t usually present.
The only common symptom of murine or endemic typhus is fever. About half of all patients also develop a rash. Scrub typhus can be contracted in Asia, and it’s characterised by a severe fever, headache and muscle pain. An eschar, cough, enlarged lymph nodes and encephalitis (inflammation of the brain) may also occur in some patients.
The symptoms of ehrlichiosis and anaplasmosis are similar to those of other rickettsial diseases. However, they’re also known to significantly reduce white blood cell count in affected people.
Is Rickettsia The Same As Lyme Disease?
Rickettsiosis and Lyme disease share several symptoms in their early stages, such as fever, headache, fatigue, malaise and muscle pain. Moreover, all of these symptoms also overlap with those of the flu and other non-specific viral infections, making diagnosis even more challenging.
The only distinctive sign of Lyme disease is the circular bull’s eye rash that develops around the tick bite within a few weeks. However, the rash can also appear elsewhere on the body, and in 20-30% of patients it’s not seen at all.
The diagnosis of Lyme and rickettsial diseases is usually based on a combination of factors, including signs, symptoms, patient history and laboratory tests. Unfortunately, currently there aren’t any completely reliable diagnostic tests available for Lyme disease: in the first weeks after infection, there’s a 60% rate of false negative results. Serological assays for rickettsiosis are more reliable, but these can take 10–12 days to provide a decisive result.
What To Do If You Think You’ve Been Infected With Rickettsia
Ticks are very tiny, and their bites aren’t painful. Many people don’t even realise they’ve been bitten.
It’s important to note that being bitten by a tick doesn’t mean you’ve contracted an illness. In fact, out of the approximately 800 different tick species in the world, less than 60 can transmit infections to humans and animals. Most types of tick also have to be attached to the host’s body for an extended period of time in order to pass on any bacteria.
Nevertheless, you must see your doctor if you have a fever and any other flu-like symptoms or a rash shortly after being bitten by a tick. You should also arrange a medical appointment if you don’t recall being bitten but you do experience some suspicious symptoms within a few weeks of returning from a high-risk area. Be sure to tell your doctor about your recent travels, so that they can evaluate the probability of a tick-borne infection and order any appropriate diagnostic tests.