Let us begin with understanding what Rickettsia is and what are the means by which it can infect us before getting to the symptoms. A Rickettsia is a small, Gram-negative, aerobic, coccobacillus (a type of rod-shaped bacterium) that is an obligate intracellular parasite of the eucaryotic cells (cells having a nucleus which carry genetic matter). These bacteria may reside in the cytoplasm as well as within the nucleus of the cell invaded by them. They reproduce via binary fission and metabolize host-derived glutamae through aerobic respiration and citric acid cycle. Common insects like ticks, mites, lice (both body and head lice), etc., are major carriers of Rickettsia.
Symptoms of Rickettsia
The initial symptoms include fever, headache, myalgia, gastroenteric dysfunctions, inflammation of the lymph nodes, malaise, etc. A rash often appears after a few days of the onset of fever, the appearance of which depends upon the type of the disease. For instance, Rickettsia problems like scrub typhus, tick typhus, and Rickettsialpox are symptomized by appearance of lesions on skin at the sites of the insect bites. However, severe cases of infection can exhibit complicated symptoms, such as restricted respiratory sufficiency, neurological disturbances, renal failure, gastrointestinal hemorrhage, and opportunistic viral, and fungal infection. Rickettsia is a genus of bacteria that falls under the bacterial family
Rickettsiaceae of the order
Rickettsiales. The Rickettsiae that infect humans can be sub divided into 3 distinct groups:
- Spotted Fever Group
- Epidemic Typhus Group
- Scrub Typhus Group
Spotted Fever Group of bacteria are responsible for causing diseases, like Rocky Mountain Spotted Fever, Boutonneuse fever, Rickettsialpox, Siberian tick typhus, Oriental spotted fever, and Australian tick typhus. This group can be found distributed all over the Western hemisphere, Mediterranean Nations, Africa, India, Southwest Asia including Mongolia, China, and Japan, USA, former Soviet countries, Siberia, and Australia. The primary carriers of this group of bacteria are ticks and Rickettsiae belonging to this group attack human vascular endothelial cells, eliciting inflammatory response as one of the primary Rickettsia symptoms. The Rickettsiae belonging to the Spotted Fever Group are:
- R. rickettsii
- R. akari
- R. conorii
- R. sibirica
- R. australis
- R. japonica
An interesting observation about this group of organisms is that they exist in all continents except Antarctica. Also, it is unusual for these bacteria to occur in winter.
Epidemic Typhus Group of Rickettsiae are primarily louse-born, sometimes flea-born, and infect the human vascular endothelial cells, causing widespread
vasculitis. As opposed to the Spotted Fever Group, this group of organisms mainly occur in winter. Since it is carried by lice, it spreads and manifests under conditions of crowd and poor sanitation. Rickettsiae belonging to this group are:
- R. prowazekii
- R. typhi
- R. felis
Rickettsia symptoms induced by this group are similar to the symptoms of
murine typhus.
Scrub Typhus Group consists of only one microorganism, the
R. tsutsugamushi or the
Orientia tsutsugamushi. It is transmitted to humans via the bite of
trombiculid mites. Scrub typhus is prevalent throughout much of Asia and Australia. It shares the dominant symptom of widespread microvascular damage with Spotted Fever and Epidemic Typhus.
All Rickettsia problems begin with the bite of an arthropod carrier or through cutaneous abrasions contaminated by flea/louse excreta. Rickettsia infection begins with introduction of the Rickettsiae into the skin. These organisms enter the dermal cells and spread intracellularly with endothelial cell-to-cell spread. The most prominent patho-physiological impact is, increased vascular permeability with consequent abnormal water retention, loss of blood volume, abnormally low levels of albumin in blood serum, reduced osmotic pressure, and unnaturally low blood pressure. These may lead to fatal consequences and may result in
pulmonary edema and
adult respiratory distress syndrome, shock, or even
acute tubular necrosis.
In case you experience any of the aforementioned symptoms, antibiotics like
chlorampenicol and
tetracycline are effective cures.
Doxycycline, a semi synthetic tetracycline, is a sure shot cure for Rocky Mountain Spotted fever. However, it is advisable to consult a registered medical practitioner before trying out any medication on yourself. Prevention is always better than cure though! The best way to prevent Rickettsia infection and avoid the above mentioned symptoms is to maintain personal hygiene, avoid crowded and dirty places as much as possible, and if at all going to such places, wear light-colored clothes so that you can see if you got any fleas/ticks/mites/lice on you. Also, wearing clothes which cover the entire body when visiting possible bug prone areas may help keep the lice and ticks out. Stay clean, stay healthy, and stay 'de-bugged'!
Disclaimer: This Buzzle article is for informative purposes only, and it should not be used as a replacement for expert medical advice.