Anterior ischemic optic neuropathy associated with rickettsia conorii infection

Infectious optic neuropathy (ION), how to recognise it and manage it

Optic neuropathy can be of infectious or non-infectious/idiopathic aetiology. Many infectious organisms can cause optic neuropathy that can be of varied presentation including papillitis, retrobulbar optic neuritis, neuroretinitis, and optic perineuritis. Detailed history, ocular, systemic/neurologic examination along with appropriate laboratory evaluation can help clinicians to identify the infectious agent causing optic neuropathy. In spite of recent advanced techniques in serological testing and molecular diagnostics like polymerase chain reaction (PCR), the identification of these pathogens is still a diagnostic challenge. It is ideal to have an infectious disease (ID) consultant in the management team, as most of these infections are multisystem involving diseases. Most infectious agents can be effectively treated with specific antibiotics, with or without corticosteroid therapy, but visual recovery is highly variable and depends entirely on early diagnosis of the causative agent. This review article will provide an overview of common pathogens involved in ION and will describe their management paradigms.

Distribution of different Rickettsia species in countries of the WHO Eastern Mediterranean (WHO-EMRO) region: An overview

SUBJECT

Rickettsia is a zoonotic bacterial pathogen transmitted by vectors and has extensive reservoirs in animal and human populations. Rickettsiosis is a public health problem all over the world. However, comprehensive information on the geographical distribution of different Rickettsia species, infection status of reservoirs, vectors, and human cases is lacking in most parts of the world. Therefore, this study aimed to investigate the geographical distribution of different Rickettsia species and their vectors in countries of the WHO-EMRO region.

METHODS

In this review study, a search was conducted for reports and published studies on Rickettsia species from WHO-EMRO region countries in various databases from 1995 to 2022. Finally, the reported status of human cases, reservoirs, and vectors associated with each species in different countries was documented.

RESULTS

Reports of infections related to the detection of Rickettsia species were only available for 15 out of 22 WHO-EMRO member countries. A total of twenty-four Rickettsia species, including R. sibrica, R. lusitaniae, R. africae, R. prowazekii, R. felis, R. typhi, R. rickettsii, R. aeschlimannii, R. conorii, R. massiliae, R. helvetica, R. monacensis, R. rhipicephali, R. bellii, R. asembonensis, R. hoogstraalii, R. andeanae, R. raoultii, R. asiatica, R. slovaca, R. australis, R. barbariae, Candidatus R. amblyommii, and Candidatus R. goldwasserii, were reported from WHO-EMRO member countries. Furthermore, human cases infected with six different Rickettsia species, including R. sibrica, R. prowazekii, R. felis, R. typhi, R. rickettsii, R. aeschlimannii, R. conorii, R. massiliae, and R. helvetica, were reported from these countries.

CONCLUSION

The vast diversity of Rickettsia vectors has contributed to the ongoing discovery of new Rickettsia species. Therefore, further research on the reservoir hosts of Rickettsia infections in the understudied WHO-EMRO region is crucial. This research sheds light on Rickettsia disease's epidemiology and transmission dynamics in this region.

SWEPT-SOURCE OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY IN RICKETTSIAL RETINITIS

PURPOSE

To report optical coherence tomography angiography findings in a patient with rickettsial retinitis.

METHODS

A 29-year-old man complaining of acute blurring vision in the right eye associated with Rickettsia conorii infection underwent a comprehensive ocular examination, fluorescein angiography, spectral-domain optical coherence tomography, and swept-source optical coherence tomography angiography.

RESULTS

Funduscopy showed two large areas of retinitis in the inferior macula along the distribution of the inferotemporal artery with associated retinal hemorrhages, retinal edema, and serous retinal detachment. Fluorescein angiography showed early hypofluorescence and late staining of white retinal lesions and associated adjacent retinal vascular leakage and optic disc hyperfluorescence. Optical coherence tomography angiography showed hypointense dark areas in the superficial capillary plexus and larger hypointense areas in the deep capillary plexus, outer retina, and choriocapillaris layer. The patient was treated with doxycycline and prednisone. Six weeks after presentation, retinal changes seen at the acute phase had resolved, leading to mild residual retinal pigment epithelial changes. Fluorescein angiography showed retinal capillary nonperfusion within areas of resolved retinitis. Spectral-domain optical coherence tomography findings included inner retinal atrophy, intraretinal cysts, and disruption of ellipsoid zone and interdigitation zone. Swept-source optical coherence tomography angiography showed well-delineated hypointense greyish areas of retinal capillary nonperfusion in both the superficial and deep capillary plexuses. Visual field testing revealed the presence of a corresponding paracentral defect.

CONCLUSION

Optical coherence tomography angiography may be a valuable noninvasive imaging technique for detecting and analyzing occlusive complications associated with rickettsial retinitis.

[Tropical ophthalmology : Intraocular inflammation caused by "new" infectious pathogens and travel-related infections]

A number of "new" (emerging) infections that can also cause inflammatory eye changes are appearing and becoming increasingly important. In the past, diseases such as chikungunya, dengue fever or West Nile virus infections were endemic in tropical regions, but are now expanding worldwide and causing significant morbidity and even mortality. "Globalization" and human migration are important factors leading to the import of these infections. Climate changes are probably even more important. Increasing temperatures provide suitable conditions for new vectors, and may lead to autochthonous transmission of infectious pathogens. Diagnosis of these diseases requires not only careful assessment of medical and travel history, but also the application of specific laboratory diagnostic tests. A broad spectrum of ocular involvement has been reported, with frequent posterior segment involvement. Emerging infections should therefore be considered in the differential diagnosis of retinitis, chorioretinitis, retinal vasculitis and optic neuropathy in a patient living in or traveling back from an endemic area. Since these infections are often vector (insect) borne and effective treatments are almost uniformly lacking, prevention is at least as important as prompt diagnosis and initiation of supportive care. Here, we focus on Chikungunya, Dengue fever, Ebola fever, the West Nile virus and Rickettsioses, which frequently demonstrate ocular involvement.

The eye and tick-borne disease in the United States

PURPOSE OF REVIEW

Tick-borne diseases are increasing in incidence and geographic distribution. Several diseases endemic to the United States have ophthalmic manifestations, including the most common tick-borne disease, Lyme borreliosis. As ocular complaints may lead a patient to seek medical evaluation, it is important to be aware of the systemic and ophthalmic manifestations of tick-borne diseases in order to make the correct diagnosis.

RECENT FINDINGS

Vision-threatening ophthalmic manifestations are relatively common in Lyme disease and Rocky Mountain spotted fever. Ocular involvement is rare in babesiosis, tick-borne relapsing fever, Powassan encephalitis, ehrlichiosis, anaplasmosis, and Colorado tick fever.There are clear guidelines for diagnosis and treatment of Lyme disease; however, confusion and misinformation among the general public as well as controversy about chronic or late-stage Lyme disease can impact the evaluation of ophthalmic disease. Furthermore, there are many gaps in our knowledge regarding the pathophysiology of ocular borreliosis although it seems likely that Lyme uveitis is rare in the United States.

SUMMARY

Knowledge of systemic and ophthalmic manifestations combined with an understanding of the epidemiology of disease vectors is crucial for the diagnosis of tick-borne diseases.

Infectious optic neuropathies: a clinical update

Different forms of optic neuropathy causing visual impairment of varying severity have been reported in association with a wide variety of infectious agents. Proper clinical diagnosis of any of these infectious conditions is based on epidemiological data, history, systemic symptoms and signs, and the pattern of ocular findings. Diagnosis is confirmed by serologic testing and polymerase chain reaction in selected cases. Treatment of infectious optic neuropathies involves the use of specific anti-infectious drugs and corticosteroids to suppress the associated inflammatory reaction. The visual prognosis is generally good, but persistent severe vision loss with optic atrophy can occur. This review presents optic neuropathies caused by specific viral, bacterial, parasitic, and fungal diseases.

New infectious etiologies for posterior uveitis

Emergent and resurgent arthropod vector-borne diseases are major causes of systemic morbidity and death and expanding worldwide. Among them, viral and bacterial agents including West Nile virus, Dengue fever, Chikungunya, Rift Valley fever, and rickettsioses have been recently associated with an array of ocular manifestations. These include anterior uveitis, retinitis, chorioretinitis, retinal vasculitis and optic nerve involvement. Proper clinical diagnosis of any of these infectious diseases is based on epidemiological data, history, systemic symptoms and signs, and the pattern of ocular involvement. The diagnosis is usually confirmed by the detection of a specific antibody in serum. Ocular involvement associated with emergent infections usually has a self-limited course, but it can result in persistent visual impairment. There is currently no proven specific treatment for arboviral diseases, and therapy is mostly supportive. Vaccination for humans against these viruses is still in the research phase. Doxycycline is the treatment of choice for rickettsial diseases. Prevention, including public measures to reduce the number of mosquitoes and personal protection, remains the mainstay for arthropod vector disease control. Influenza A (H1N1) virus was responsible for a pandemic human influenza in 2009, and was recently associated with various posterior segment changes.

Emergent infectious uveitis

Infectious causes should always be considered in all patients with uveitis and it should be ruled out first. The differential diagnosis includes multiple well-known diseases including herpes, syphilis, toxoplasmosis, tuberculosis, bartonellosis, Lyme disease, and others. However, clinicians should be aware of emerging infectious agents as potential causes of systemic illness and also intraocular inflammation. Air travel, immigration, and globalization of business have overturned traditional pattern of geographic distribution of infectious diseases, and therefore one should work locally but think globally, though it is not possible always. This review recapitulates the systemic and ocular mainfestations of several emergent infectious diseases relevant to the ophthalmologist including Rickettsioses, West Nile virus infection, Rift valley fever, dengue fever, and chikungunya. Retinitis, chorioretinitis, retinal vasculitis, and optic nerve involvement have been associated with these emergent infectious diseases. The diagnosis of any of these infections is usually based on pattern of uveitis, systemic symptoms and signs, and specific epidemiological data and confirmed by detection of specific antibody in serum. A systematic ocular examination, showing fairly typical fundus findings, may help in establishing an early clinical diagnosis, which allows prompt, appropriate management.

Novel infectious agents causing uveitis

In any patient with uveitis, an infectious cause should be ruled out first. The differential diagnosis includes multiple well-known diseases including herpes, syphilis, toxoplasmosis, tuberculosis, bartonellosis, Lyme disease, and others. However, clinician should be aware of emerging infectious agents as potential causes of systemic illness and also intraocular inflammation. Air travel, immigration, and globalization of business have overturned traditional pattern of geographic distribution of infectious diseases, and therefore one should work locally but think globally. This review recapitulates the systemic and ocular manifestations of several emergent infectious diseases relevant to the ophthalmologist including Rickettsioses, West Nile virus infection, Rift valley fever, Dengue fever, and Chikungunya. Retinitis, chorioretinitis, retinal vasculitis, and optic nerve involvement have been associated with these emergent infectious diseases. The diagnosis of any of these infections is usually based on pattern of uveitis, systemic symptoms and signs, and specific epidemiological data and confirmed by detection of specific antibody in serum. A systematic ocular examination, showing fairly typical fundus findings, may help establish an early clinical diagnosis, which allows prompt, appropriate management.

Warmer weather linked to tick attack and emergence of severe rickettsioses

The impact of climate on the vector behaviour of the worldwide dog tick Rhipicephalus sanguineus is a cause of concern. This tick is a vector for life-threatening organisms including Rickettsia rickettsii, the agent of Rocky Mountain spotted fever, R. conorii, the agent of Mediterranean spotted fever, and the ubiquitous emerging pathogen R. massiliae. A focus of spotted fever was investigated in France in May 2007. Blood and tissue samples from two patients were tested. An entomological survey was organised with the study of climatic conditions. An experimental model was designed to test the affinity of Rh. sanguineus for biting humans in variable temperature conditions. Serological and/or molecular tools confirmed that one patient was infected by R. conorii, whereas the other was infected by R. massiliae. Dense populations of Rh. sanguineus were found. They were infected with new genotypes of clonal populations of either R. conorii (24/133; 18%) or R. massiliae (13/133; 10%). April 2007 was the warmest since 1950, with summer-like temperatures. We show herein that the human affinity of Rh. sanguineus was increased in warmer temperatures. In addition to the originality of theses cases (ophthalmic involvements, the second reported case of R. massiliae infection), we provide evidence that this cluster of cases was related to a warming-mediated increase in the aggressiveness of Rh. sanguineus, leading to increased human attacks. From a global perspective, we predict that as a result of globalisation and warming, more pathogens transmitted by the brown dog tick may emerge in the future.

The impact of climate on the behaviour of the worldwide dog tick Rhipicephalus sanguineus is a cause of concern. This tick is a vector for life-threatening organisms including Rickettsia rickettsii, the agent of Rocky Mountain spotted fever, R. conorii, the agent of Mediterranean spotted fever, and the ubiquitous emerging pathogen R. massiliae. A focus of spotted fever was investigated in France in May 2007. One patient was found to be infected by R. conorii, whereas the other was infected by R. massiliae. Theses cases were original because of ophthalmic involvements, and the report of the second case of R. massiliae infection in the scientific literature. During an entomological survey, dense populations of Rh. sanguineus were found in the house where the patient had been bitten by ticks. Ticks were infected with either R. conorii or R. massiliae. Interestingly, April 2007 was the warmest since 1950, with summer-like temperatures. In this work, we show that the human affinity of Rh. sanguineus is increased in warmer temperatures, and provide evidence that this cluster of cases was related to a warming-mediated increase in the aggressiveness of Rh. sanguineus, leading to increased human attacks. From a global perspective, we predict that as a result of globalisation and warming, more pathogens transmitted by the brown dog tick may emerge in the future.