Rickettsial Infections - Causes, Symptoms, and Diagnosis

What Are Rickettsial Infections?

Many microbial infections exist and create trouble for other living organisms. Rickettsial infections are an array of diseases caused by a peculiar microbial genus. Rickettsial infections are quite a rare form of infections depicted in the form of specific skin rashes along with diverse other manifestations. It exhibits various manifestations ranging from mild fever to deadly infections. They tend to mimic many other viral conditions, thus, making the diagnosis process bit challenging. Rickettsioses is the widely used synonym for rickettsial infections.

What Causes Rickettsial Infection?

• Bacterias belonging to a specific order, Rickettsiales, are responsible for these spectra of infections. Rickettsia, orientia, ehrlichia, neoehrlichia, orientia tsutsugamushi, neorickettsia and anaplasma are the bacterial genus that can also bring about rickettsial infections.

• They are parasitic gram-negative cocco bacilli carried on from one organism to another by certain vector organisms like lice, mites, ticks, and fleas. Upon accidental exposure to infected fluid or biting, humans acquire microbes from these vectors (agents).

• Rickettsial infections do not spread directly; however, they can spread via infected blood, blood products, and organ transfer. These cocco bacilli specifically attack blood vessels in the human body and bring about complex symptoms.

What Are the Different Categories of Rickettsial Microbes?

Rickettsial infection is a broad terminology that enwraps several diseases caused by microbes that comes under the order Rickettsiales. Some of the widely reported forms of rickettsial microbes include the following disease conditions:

1. Spotted Fever Group: It includes different rickettsia species like Rickettsia rickettsii, Rickettsia akari, and Rickettsia conorii.

2. Typhus Group: This category consists of two specific microbial species: Rickettsia typhi and Rickettsia prowazekii.

3. Scrub Typhus Group: This group comprises microbes from a single species, Orientia tsutsugamushi.

4. Others: The rest of the species under the order Rickettsiales fall into this group.

Which Are the Important Rickettsial Infections?

There is a great deal of rickettsial infections, and some of the widely reported infections include the following:

• Rocky Mountain spotted fever.

• Brazilian spotted fever.

• Rickettsialpox.

• Louse-borne typhus.

• Siberian tick typhus.

• Brill-Zinsser disease.

• Oriental spotted fever.

• Murine typhus.

• Australian tick typhus.

• Boutonneuse fever.

• Tsutsugamushi disease.

What Are the Symptoms Associated With Rickettsial Infection?

Clinical manifestations of rickettsial infection broadly vary with the type of infection and the microbes that are involved with the infections. Some of the frequently reported symptoms include the following:

• Fever: Generally high grade, more than 38 degrees celsius, is manifested in rickettsial infections. The intensity, nature, and onset of the fever largely depend on the type of rickettsial infection and vary accordingly.

• Rash: Skin rashes are the peculiar trademark feature of rickettsial infections. It appears as small, flat, pinkish patches and later acquires an embossed (raised) structure. It is often manifested in numerous petechiae (pinpoint bleedings). In the more severe stages, these bleeding points tend to collapse and merge, giving rise to large, intensely pigmented, bruising patches (ecchymosis). Typically at the tick bite site, specific necrotic (dead) skin can be seen by the term eschar. Rashes typically appear over the extremities like hands and legs. However, they are spotted in other areas as well.

• Headache: Infected patients often elicit severe aches, especially in the front region of the head (frontal headache). These kinds of headaches are manifested in elderly patients.

• Lymphadenopathy: As an infectious condition, bulging of the lymph nodes is frequently manifested in rickettsial infections.

• Myalgia: Certain patients occasionally develop muscle pain, typically in the leg muscles associated with rickettsial infections.

• Neurological Issues: Neurological troubles often reflect in the form of altered visual and auditory functions. Some of the patients elicit mental confusion and disorientation. Rickettsial infections have the potential to lead to grave complications like meningoencephalitis syndrome. Though rare, it can endanger a person's life without prompt treatment therapies.

• Renal Issues: Renal dysfunctions are often encountered if left untreated, eventually paving the way for renal failure.

• Respiratory Issues: Cough is a frequently encountered respiratory trouble. Occasionally it progresses into complications like pulmonary edema and interstitial pneumonitis.

• Gastrointestinal Issues: Diarrhea, belly pain, and nausea are frequently encountered in this infectious condition.

How Are Rickettsial Infections Diagnosed?

Detailed analysis of the clinical findings often gives a clue to the diagnosis. A recent history showing susceptibility to tick bites is often critical in diagnosing. However, the diagnosis can only be confirmed with the help of appropriate diagnostic tests and procedures.

• Blood Tests: Whenever the human body encounters any infection, there will be an associated hike in the white blood cell (WBC) counts. Likewise, the rickettsial infection blood picture often reflects the peaking of WBC (leucocytosis) along with the erythrocyte sedimentation rate (ESR). In addition, it also elicits depletion in the platelet count (thrombocytopenia). A significant downfall in the albumin and sodium level in the blood enhances the diagnosis and aids in ruling out other possible infectious diseases. Blood pictures, at times, elicit a negative response in the initial phase and may mislead the diagnosis.

• Indirect Immunofluorescent Assay (IFA): It helps uncover the presence of antibodies specific to rickettsial infections. Generally, immunoglobulin G (IgG) can be recognized in the initial stage of the disease and facilitates early diagnosis of the condition.

• Weil- Felix Test: It also works by finding out the rickettsial-specific antibody. It is not extensively advised because of its questionable sensitivity.

• Polymerase Chain Reaction Assay: This test shows the presence of genetic material (deoxyribonucleic acid) specific for the rickettsial group of microbes.

• Cerebrospinal Fluid Analysis: A hike in the normal cell count in the cerebrospinal fluid is often elicited in rickettsial infections.

• Biopsy: A biopsy specimen gathered from the site of the tick bite or skin rash aids in confirming the diagnosis of the condition.

What Are the Treatment Interventions Available for Rickettsial Infections?

Treatment strategy largely depends on the condition's stage and the symptoms' severity. Antibiotics are routinely preferred to deal with rickettsial infections as they are caused chiefly by microbes. Extensively prescribed antibiotics include Doxycycline and Chloramphenicol. Clarithromycin is also advised in the early stages. Symptomatic management is also advocated in severe cases to tackle the complications.

Conclusion

Rickettsial infections are pretty rare and deadly if not treated at the right time. If diagnosed early, it can be easily tackled with antibiotic treatment. Prompt diagnosis and timely treatment are the two important parameters that determine the prognosis of the condition.