Méningoencéphalite à Rickettsia conorii chez un nourrisson

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.

Human-biting ticks and zoonotic tick-borne pathogens in North Africa: diversity, distribution, and trans-Mediterranean public health challenges

North Africa is home to more than 200 million people living across five developing economies (Egypt, Libya, Tunisia, Algeria, and Morocco) and two Spanish exclaves (Ceuta and Melilla), many of whom are impacted by ticks and tick-borne zoonoses. Populations in Europe are also increasingly vulnerable to North African ticks and tick-borne zoonoses due to a combination of climate change and the movement of ticks across the Mediterranean on migratory birds, human travellers, and trafficked wildlife. The human-biting ticks and tick-borne zoonoses in North Africa are reviewed along with their distribution in the region. We also assess present and future challenges associated with ticks and tick-borne zoonoses in North African and highlight opportunities for collaboration and coordination between governments in Europe and North Africa to address public health challenges posed by North African ticks and tick-borne zoonoses.

Mediterranean Spotted Fever: Current Knowledge and Recent Advances

Mediterranean spotted fever (MSF) is an emerging tick-borne rickettsiosis of the spotted fever group (SFG), endemic in the Mediterranean basin. By virtue of technological innovations in molecular genetics, it has been determined that the causative agent of MSF is Rickettsia conorii subspecies conorii. The arthropod vector of this bacterium is the brown dog tick Rhipicephalus sanguineus. The true nature of the reservoir of R. conorii conorii has not been completely deciphered yet, although many authors theorize that the canine population, other mammals, and the ticks themselves could potentially contribute as reservoirs. Typical symptoms of MSF include fever, maculopapular rash, and a characteristic eschar (“tache noire”). Atypical clinical features and severe multi-organ complications may also be present. All of these manifestations arise from the disseminated infection of the endothelium by R. conorii conorii. Several methods exist for the diagnosis of MSF. Serological tests are widely used and molecular techniques have become increasingly available. Doxycycline remains the treatment of choice, while preventive measures are focused on modification of human behavior and vector control strategies. The purpose of this review is to summarize the current knowledge on the epidemiology, pathogenesis, clinical features, diagnosis, and treatment of MSF.

Mediterranean spotted fever in child and adult patients: investigation from an endemic region in Bulgaria

OBJECTIVES

Mediterranean spotted fever (MSF) is a tick-borne endemic disease caused by Rickettsia conorii conorii and transmitted to humans by the brown dog tick Rhipicephalus sanguineus. It is characterized by fever, maculopapular rash and a tick bite skin lesion "tache noire". The disease affects all age groups and usually has mild to moderate course. It has long been considered a benign infection. However, very severe "malignant" forms with fatal outcome strongly influenced by the patients' age were also observed. We aimed to reveal the features of MSF in children by comparing them with some of the disease patterns in adults.

METHODS

Our prospective study data are based on the monitoring of all inpatients of the Clinic of Infectious Diseases in Plovdiv City and environs, the largest MSF endemic region in Bulgaria. The total number of patients admitted and treated for MSF over a study period of 10 years is 549, the incidence reaching 9.44/100,000. MSF is confirmed by antibody response to a specific antigen measured by indirect immunofluorescence assay (IFA). IgG ≥ 128 and/or IgM > 64 were considered to be indicative of acute infection.

RESULTS

Eighty-five (15.48%) patients were children up to 14 years of age and 464 (84.52%) were aged 15-85 years. The skin lesion "tache noire" was present in 73.68% of children, and in 76.93% of the older age groups; symptoms as anorexia, nausea, vomiting, abdominal pain, and diarrhoea were more frequent in children, till general weakness and malaise was prevalent in adults. Children accounted approximately for 70% of the disease mild forms. No lethality was registered in this age group. Even though there were isolated cases of severe and malignant forms, children did not undergo the fatal complications seen in adults.

CONCLUSION

Knowledge of the peculiarities of MSF in children will contribute to children's health protection, timely diagnose and disease prevention.

Rickettsial infections of the central nervous system

As a result of migrations and globalization, people may face a possible increase in the incidence of central nervous system rickettsial infections (CNS R). These diseases, caused by Rickettsia species and transmitted to humans by arthropod bites, are putatively lethal. However, the diagnosis of CNS R is challenging and often delayed due to their nonspecific clinical presentation and the strict intracellular nature of rickettsiae. Furthermore, transfer of rickettsiae to the brain parenchyma is not yet understood. The aim of this review is to analyze and summarize the features and correlated findings of CNS R in order to focus attention on these intriguing but frequently neglected illnesses. We also incorporated data on CNS infections caused by Rickettsia-related microorganisms.

Macrophagic activation syndrome related to an infection by Rickettsia conorii in a child

Since the Arab Spring, a resurgence of zoonotic diseases such as rickettsiosis, endemic in the Mediterranean basin, has been observed. It preferentially infects microvascular endothelial cells of mammalian hosts inducing vasculitis with endothelial injury. Rickettsioses are considered benign infectious diseases. Severe systemic manifestations have been reported and are often explained by a delay in diagnosis. We present a case of hemophagocytic syndrome occurring in a 4-year-old Libyan girl as a complication of Mediterranean spotted fever. Rickettsial infection was confirmed by serology and the patient was treated with clarithromycin, with a favorable outcome.