Widespread subcutaneous necrosis in spotted fever group Rickettsioses from the coastal belt of Sri Lanka- a case report

Serological profile of patients suspected with non-scrub typhus rickettsioses

BACKGROUND

Rickettsial pathogens are Gram-negative, obligate intracellular bacteria. They are transmitted by arthropods and are responsible for a wide variety of disease, from minor to life-threatening, which have a global effect on human health. Limited data are available on the prevalence of rickettsial diseases from India, and the disease epidemiology is not fully described. This study aimed to diagnose non-scrub typhus rickettsioses including spotted fever and typhus group of Rickettsia in clinically suspected patients by using standard serological tests and recognition of common epidemiological conditions and clinical manifestations.

METHODS

During the study period, a total of 700 patients of all ages with acute febrile illness were enrolled. Patients were screened for rickettsial infection using IgM Enzyme-linked immunosorbent assay (ELISA) and Immunofluorescence assay (IFA) was performed to confirm the ELISA positive results. The relevant demographic, clinical, and laboratory details of patients were documented and analyzed.

RESULTS

Of 700 samples tested, 141 (20.2%) were found to be positive for IgM antibodies against rickettsioses using ELISA and IFA. SFGR was positive in 15 (2.2%), TGR was positive in 112 (16%) and 14 (2%) samples were positive for both groups. 20 (14.2%) patients required admission to the intensive care unit (ICU), and 24 (17%) in-hospital deaths occurred.

CONCLUSIONS

The prevalence of rickettsioses in India appears to be underestimated; therefore, increased awareness and improved diagnostic testing could facilitate early detection of cases, pathogen-targeted appropriate treatment, and improved outcomes for patients. Despite the fact that Rickettsiae can be isolated or detected using molecular techniques in clinical specimens, serology still remains the most commonly used diagnostic method for rickettsioses around the world. Our study helps bridge the gap of limited data on Rickettsia in north India and could be useful for future epidemiological investigation of rickettsial diseases and outbreaks.

Rickettsia-Host-Tick Interactions: Knowledge Advances and Gaps

Ticks are hematophagous ectoparasites capable of transmitting multiple human pathogens. Environmental changes have supported the expansion of ticks into new geographical areas that have become the epicenters of tick-borne diseases (TBDs). The spotted fever group (SFG) of Rickettsia frequently infects ticks and causes tick-transmitted rickettsioses in areas of endemicity where ixodid ticks support host transmission during blood feeding. Ticks also serve as a reservoir for SFG Rickettsia. Among the members of SFG Rickettsia, R. rickettsii causes Rocky Mountain spotted fever (RMSF), the most lethal TBD in the United States. Cases of RMSF have been reported for over a century in association with several species of ticks in the United States. However, the isolation of R. rickettsii from ticks has decreased, and recent serological and epidemiological studies suggest that novel species of SFG Rickettsia are responsible for the increased number of cases of RMSF-like rickettsioses in the United States. Recent analyses of rickettsial genomes and advances in genetic and molecular studies of Rickettsia provided insights into the biology of Rickettsia with the identification of conserved and unique putative virulence genes involved in the rickettsial life cycle. Thus, understanding Rickettsia-host-tick interactions mediating successful disease transmission and pathogenesis for SFG rickettsiae remains an active area of research. This review summarizes recent advances in understanding how SFG Rickettsia species coopt and manipulate ticks and mammalian hosts to cause rickettsioses, with a particular emphasis on newly described or emerging SFG Rickettsia species.

A case of a young boy with hyper-fibrinolysis associated with natural fibrin precipitates suspected to have occurred through a novel coagulation and fibrinolysis mechanism

An 8-year-old Japanese boy with no underlying disease presented with severe intramuscular hematoma of the hip, and was admitted for a disseminated intravascular coagulation-like state with fibrinolytic dominance. Laboratory examinations revealed severe hyper-fibrinolysis with elevated markers, markedly shortened euglobulin clot lysis time, mildly decreased prothrombin, and severely decreased fibrinogen and factor XIII. Natural fibrin precipitates rapidly appeared in citrate-treated, ethylene-diamine-tetra-acetic-treated, and heparin-treated samples, but not in argatroban-treated samples, indicating that the mechanism of thrombin and fibrin formation was Ca²⁺-independent. The precipitates were physically similar to thrombin-triggered plasma fibrin. A global coagulation assay revealed that thrombin generation potentials were normal throughout the clinical course, whereas plasmin generation was already detected before initiation of fibrin formation in the acute phase. This phenomenon disappeared with time. Changes in coagulation abnormalities and nature of fibrinolysis paralleled those seen in specific markers for streptococcal infections. Streptokinase was possibly involved in this disease, as SDS-polyacrylamide gel electrophoresis revealed that plasmin derived from streptokinase-plasminogen complex proteolyzed the prothrombin to approximately 35-kDa α-thrombin consisting of the A-B single chain, which was identified by NH₂-terminal sequence analysis. The involvement of streptokinase-plasminogen-prothrombin caused by streptococcal infection may be one mechanism that produces marked hyper-fibrinolysis associated with natural fibrin precipitates.

Molecular Characterization of Rickettsial Agents in Ticks (Acari: Ixodidae) from Sri Lanka

Because the majority of spotted fever group rickettsiae are transmitted to humans by tick bites, it is important to understand which ticks might play a role in transmission of rickettsial pathogens in Sri Lanka. The purpose of our study was to conduct molecular surveillance of 847 ticks collected in different locations in central Sri Lanka to determine which were infected with Rickettsia and Anaplasmataceae. Molecular methods were used to identify the ticks and the agents detected. Most ticks (Amblyomma, Haemaphysalis, and Rhipicephalus) were collected by flagging, and lower number was collected from dogs, cattle, pigs, a pangolin, and tortoises. Five spotted fever genotypes were identified: a Rickettsia africae-like agent in Amblyomma larvae, Rhipicephalus massiliae and a related genotype identified in association with the tropical type of Rhipicephalus sanguineus from dogs and Rhipicephalus haemaphysaloides from dogs and cattle, and Candidatus R. kellyi and another novel genotype (SL94) in R. haemaphysaloides. Twenty-three ticks were positive for Anaplasmataceae, including one Anaplasma and two Ehrlichia genotypes. Because the sequence database for both ticks and rickettsial agents from Sri Lanka and southern India is not extensive, additional molecular characterization of the tick species of Sri Lanka and their rickettsial agents is required to understand their pathogenic potential more completely. However, several of the agents we identified in this survey may well be pathogenic for humans and domestic animals, and should be considered as a part of epidemiological surveillance and patient management.

Two Cases of Israeli Spotted Fever with Purpura Fulminans, Sharon District, Israel

Genetic sequencing should be used to confirm cases because purpura fulminans is a rare finding.

We report a series of 5 case-patients who had Israeli spotted fever, of whom 2 had purpura fulminans and died. Four case-patients were given a diagnosis on the basis of PCR of skin biopsy specimens 3–4 days after treatment with doxycycline; 1 case-patient was given a diagnosis on the basis of seroconversion. Rickettsia spp. from the 2 case-patients who died were sequenced and identified as Rickettsia conorii subsp. israelensis. Purpura fulminans has been described in association with R. rickettsii and R. indica, but rarely with R. conorii subsp. israelensis.

Streptococcus pyogenes-purpura fulminans as an invasive form of group A streptococcal infection

BACKGROUND

Streptococcus pyogenes is an uncommon pathogen of purpura fulminans, and the pathogenesis of S. pyogenes-purpura fulminans remains unclear because of paucity of cases. We reported a pediatric case of S. pyogenes-purpura fulminans with literature review of the disease.

CASE PRESENTATION

A 3-year-old boy showed limping, lethargy and acral gangrene within 24 h. A diagnosis of S. pyogenes-purpura fulminans was made for bacterial isolation from throat and peripheral blood. Intensive therapy led to a survival with amputation of the left distal metatarsal bone, and normal development. The isolated M12 carried no mutation of csrS/R or rgg. Thrombophilia or immunodeficiency was excluded.

DISCUSSION

Twelve-reported cases (9 pediatric and 3 elderly) of S. pyogenes-purpura fulminans started with shock and coagulopathy. Five patients age < 8 years had no underlying disease and survived. One youngest and two immunocompromised patients died.

CONCLUSION

Streptococcus pyogenes-acute infectious purpura fulminans is a distinctive rare form of aggressive GAS infections.

Update on Tick-Borne Bacterial Diseases in Travelers

PURPOSE OF REVIEW

Ticks are the second most important vectors of infectious diseases after mosquitoes worldwide. The growth of international tourism including in rural and remote places increasingly exposes travelers to tick bite. Our aim was to review the main tick-borne infectious diseases reported in travelers in the past 5 years.

RECENT FINDINGS

In recent years, tick-borne bacterial diseases have emerged in travelers including spotted fever group (SFG) rickettsioses, borrelioses, and diseases caused by bacteria of the Anaplasmataceae family. African tick-bite fever, due to Rickettsia africae, is the most frequent agent reported in travelers returned from Sub-Saharan areas. Other SFG agents are increasingly reported in travelers, and clinicians should be aware of them. Lyme disease can be misdiagnosed in Southern countries. Organisms causing tick-borne relapsing fever are neglected pathogens worldwide, and reports in travelers have allowed the description of new species. Infections due to Anaplasmataceae bacteria are more rarely described in travelers, but a new species of Neoehrlichia has recently been detected in a traveler. The treatment of these infections relies on doxycycline, and travelers should be informed before the trip about prevention measures against tick bites.