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Beginning in 2022, Nuevo Leon, Mexico, experienced an outbreak of rickettsioses that is still ongoing despite multidisciplinary control efforts. A total of 57 cases have been confirmed, particularly affecting children. We report a high mortality rate among hospitalized persons in Nuevo Leon. Continuing efforts are required to control the outbreak.

Purpose: The aim of this work was to study the ocular manifestations and its management in spotted fever and typhus group of rickettsial disease. Methods: A retrospective analysis of 50 patients with serologically confirmed Rickettsial disease. In all patients, relevant history, investigations and treatment details were collected and they underwent complete ophthalmic evaluation including measurement of best-corrected visual acuity, anterior segment examination and dilated fundus examination. Results: Mean age was 12.5 ± 8.99 years. Of the 50 patients, 40 patients were ≤18 years of age and 27 (54%) had ocular involvement. Out of 27 patients, bilateral involvement was seen in 10 patients. Most of the patients had no ocular symptoms. Ocular findings included, Retinal vasculitis 6 (22.22%); macular edema 4 (14.81%); vasculitis with macular edema 1 (3.7%); Retinitis 7 (25.92%); Papilloedema 6 (22.22%); Papilloedema with 6th cranial nerve palsy 1 (3.7%); Isolated 6th cranial nerve palsy 1 (3.7%) and optic neuritis 1 (3.7%). Ocular involvement was more common in double antigen group (68%) than spotted fever group (50%) or Scrub typhus group (21%) (P = 0.01). Ocular involvement was seen in 94% of the patients with CNS involvement. Cases with bilateral involvement (P = 0.01), pediatric age group (P = 0.01) and CNS involvement (P = 0.02) had poor visual outcome. Conclusion: Rickettsioses patients can have ocular manifestations with predominant posterior segment involvement during acute phase of illness. Ocular involvement was more common in the double antigen group. For any patient who presents with fever and rash living in endemic area, ophthalmic evaluation should be part of routine checkup during the acute phase of illness associated with less frequent ocular symptoms.

Rickettsial diseases present as acute febrile illnesses, sometimes with inoculation eschars. We performed a systematic review of studies published between 1997 and 2017 to assess the underestimation of non-eschar rickettsial disease (NERD) relative to eschar rickettsial disease (ERD), as a cause of acute fever in patients with rickettsial diseases that commonly present with eschar(s): scrub typhus (ST), Mediterranean spotted fever (MSF), and African tick-bite fever. We compared ERD/NERD ratios according to study design: ‘complete approach’ studies, with testing performed in all patients with ‘unspecified febrile illness’; versus ‘clinical judgement’ studies, with testing performed if patients presented with specific symptoms. In ‘complete approach’ studies, ERD/NERD ratios were significantly lower, suggesting a considerable under-diagnosis of NERD in ‘clinical judgement’ studies. Based on these results, we estimate that the diagnosis of rickettsial disease was missed in 66.5% of patients with ST, and in 57.9% of patients with MSF. Study design influences the reported eschar rates in ST and MSF significantly. NERD is likely to be a vastly underdiagnosed entity, and clinicians should consider and test for the disease more often. CRD 42016053348

The pathological hallmark of scrub typhus infection is focal or disseminated vasculitis. As with other infections, antinuclear antibodies (ANA) have been previously described in scrub typhus. However, the underlying mechanisms and implications of this immunological phenomenon is not well understood. In the present work it was assessed whether ANA is associated with illness severity and outcomes. In this prospective study spanning one year, patients fulfilling the diagnostic criteria for scrub typhus were recruited. Patients with other acute infective febrile illnesses were taken as controls. ANA positivity was compared between the cases and controls. ANA in scrub typhus was assessed for correlation with disease severity, organ dysfunction and outcomes. The cohort comprised of 149 patients (scrub 89; controls 60) with mean age 46.5 (SD=16.9) yr; 48.3% were female. ANA was detected in 48 (53.9%) patients with scrub typhus and 9(15%) controls (p < 0.001). The ANA pattern was predominantly speckled (93.8%) in both scrub typhus patients and controls. In patients with scrub typhus, ANA positivity was associated with increasing APACHE-III score [Odds ratio (OR) 1.01; 95% CI 0.99-1.03; p = 0.09]. On bivariate analysis, ANA tended to be correlated with acute respiratory distress syndrome (OR 2.32; 95% CI 0.98-5.46; p = 0.06), hepatic dysfunction (OR 2.25; 95% CI 0.94-5.39, p = 0.06) and aseptic meningitis (OR 6.83; 95% CI 0.80-58.05, p = 0.08). The presence of these antibodies did not correlate with duration of hospitalization or mortality. Convalescent sera on 31 ANA positive scrub typhus patients demonstrated persistence of ANA in only 5 (16.1%) patients. The disappearance of ANA during the convalescent phase suggests that ANA is expressed during the acute phase of scrub typhus infection. Its association with organ dysfunction warrants further study of the mechanisms and impact of autoantibody formation in scrub typhus.

Background & objectives: Rickettsial and other zoonotic diseases are a latent risk for workers of veterinary clinics. The objective of this study was to evaluate the prevalence and the associated risk factors of parasitosis caused by Rhipicephalus sanguineus, and to estimate the seroprevalence of rickettsial diseases in workers of urban veterinary clinics of Juárez city, México. Methods: The participants of the study were recruited from 63 private veterinary clinics and hospitals. The serological analysis of the blood samples collected was carried out using immunofluorescence assay (IFA). The statistical analysis for prevalences, risk factors, and correlation was performed with the SAS program. Results: In total, 167 veterinary workers were included in the study. The prevalence of tick bites was 40% (67/167), and the risk factors associated with the occurrence of bites included the activities performed in the clinic and the number of labour hours spent per week. About 21% (35/167) of participants were seropositive to R. rickettsii, 28% (47/167) to Ehrlichia chaffeensis, and 24% (40/167) to Anaplasma phagocytophilum. A correlation was observed between: the number of workers in the clinics and the proportion of tick bites (r2 = 0.865); the prevalence of bites and the seropositivity of the participants to at least one pathogen (r2 = 0.924); and the number of bites per individual and infection to pathogens (r2 = 0.838). Interpretation & conclusion: Workers in urban veterinary clinics are highly exposed to tick bites and, therefore, to the diseases they transmit. Hence, it is important to implement prevention measures and perform constant monitoring of these diseases.

Background In the past decade, scrub typhus cases have been reported across India, even in regions that had no previous history of the disease. In the North-East Indian state of Mizoram, scrub typhus cases were first recorded only in 2012. However, in the last five years, the state has seen a substantial increase in the scrub typhus and other rickettsial infections. As part of the public health response, the Mizoram Government has integrated screening and line listing of scrub typhus and other rickettsial infections across all its health settings, a first in India. Here we detail the epidemiology of scrub typhus and other rickettsial infections from 2018-2022, systematically recorded across the state of Mizoram. Methodology/principal findings The line-listed data positive for scrub typhus and other rickettsial infections identified by rapid immunochromatographic test and/or Weil-Felix test from 2018-22 was used for the analysis. During this period, 22,914 cases of rickettsial infections were recorded, out of which 19,651 were scrub typhus cases. Aizawl is the worst affected, with 10,580 cases (46.17%). The average incidence of rickettsial infections is 3.54 cases per 1000 persons-year, and the case fatality rate is 0.35. Only ~2% of the reported scrub typhus cases had eschar. Multivariate logistic regression analysis indicate patients with eschar (aOR = 2.5, p<0.05), occupational workers [farmers (aOR:3.9), businessmen (aOR:1.8), construction workers (aOR:17.9); p<0.05], and children ([less than or equal to]10 years) (aOR = 5.4, p<0.05) have higher odds of death due to rickettsial infections. Conclusion The integration of systematic surveillance and recording of rickettsial diseases across Mizoram has shed important insights into their prevalence, morbidity, and mortality. This study underscores the importance of active surveillance of rickettsial infections across India, as the burden could be substantially higher, and is probably going undetected.

This study investigated the seroprevalence of Coxiella burnetii in buffaloes across several governorates in Egypt's Nile Delta. No significant variation was observed between regions (P > 0.05), although the highest prevalence was recorded in Kafr El-Sheikh (15.5%) and the lowest in Menofia (9.1%). While sex was not statistically significant, females showed a higher seroprevalence (12.4%) than males (9%). Age had a significant impact, with buffaloes over 8 years of age showed a higher prevalence (21.6%) compared to the younger age groups. Tick infestation was also significantly associated with infection, with a prevalence of 22.4% in infested animals. Buffaloes exposed to communal grazing (13.8%) or kept in contact with small ruminants (16.3%) showed increased seropositivity. Notably, animals with a history of abortion had a markedly higher prevalence (26.7%). Multivariate logistic regression analysis identified age above 8 years (OR = 6.7), tick infestation (OR = 3.0), contact with small ruminants (OR = 3.0), and abortion history (OR = 3.2) as significant risk factors. Communal grazing (OR = 1.9) and age between 5 and 8 years (OR = 2.2) were also associated with increased odds of seropositivity. These findings highlight key epidemiological factors contributing to C. burnetii infection risk in buffaloes.

Spotted fever group (SFG) rickettsioses are important zoonoses, threatening human health seriously and gradually attracting more attention in the world. SFG rickettsiae are classified as neglected pathogens. If these pathogens are detected at all, they are usually recognized very late in the infection through indirect detection of specific antibodies. Previous studies have shown that Rickettsia raoultii (R. raoultii), a member of the SFG rickettsiae, occurs with increasing incidence in remote countries. Therefore, a rapid detection method for R. raoultii is in urgently need. In this study, a R. raoultii diagnosis method by closed dumbbell-mediated isothermal amplification (R-CDA) assay targeting a conserved sequence of the outer membrane protein A (OmpA) gene with high sensitivity and specificity was developed. This assay offered a rapid and simple method for on-site detection of R. raoultii. Firstly, four pairs of R-CDA primers were designed and the optimum primer set was selected to amplify target gene specifically and effectively. Then, a pair of outer primer was designed to accelerate the reaction based on the inner primers to establish the RO-CDA reaction. In addition, the results of real-time amplification curves, melting curves and end-point colorimetric judgements showed that the established visual RO-CDA reaction could accurately detect R. raoultii without cross-reaction with other closely related pathogens. Furthermore, the detection limit of visual RO-CDA assay was 10 copies/[mu]L, which was feasible for on-site detection with merits of easy-operation, rapidity, high sensitivity, and specificity. In conclusion, the developed RO-CDA detection method could be helpful for pathogen screening and epidemic prevention at the point of care.

Rickettsia is a maternally transmitted endosymbiotic bacterium that infects most insect species. In the current study, we investigated the biological and physiological effects of Rickettsia infection on whitefly, Bemisia tabaci. Our results revealed that infection with Rickettsia increased the fertility, survivorship, and shortened the nymphal developmental duration of whitefly Bemisia tabaci. Rickettsia infected B. tabaci had significantly higher glycogen, soluble sugar and trehalose contents than those of Rickettsia negative B. tabaci individuals. When exposed to the entomopathogenic fungus Akanthomyces attenuatus and the insecticides imidacloprid and spirotetramat, Rickettsia infested B. tabaci had lower mortality rates and higher semi-lethal concentrations (LC[sub.50]). The parasitism by Encarsia formosa was also reduced by Rickettsia infection. Endosymbionts play an essential role in the biology, physiology and immunity of insects. Many insects, including the whitefly Bemisia tabaci, are infected with the facultative endosymbiont Rickettsia. However, the mutualism between Rickettsia and its whitefly host remains unclear. This study investigated the biological and physiological benefits of Rickettsia infection to B. tabaci. Results revealed that infection of Rickettsia increased the fertility, the survival rate from nymph to adult and the number of female whiteflies. In addition, this facilitation caused a significant reduction in nymphal developmental duration but did not affect percentage rate of egg hatching. Rickettsia infected B. tabaci had significantly higher glycogen, soluble sugar and trehalose contents than Rickettsia negative B. tabaci individuals. Rickettsia also improved the immunity of its whitefly hosts. Rickettsia infested B. tabaci had lower mortality rates and higher semi-lethal concentrations (LC[sub.50]) when exposed to the fungus Akanthomyces attenuatus and the insecticides imidacloprid and spirotetramat. The percentage of parasitism by Encarsia formosa was also reduced by Rickettsia infection. Overall, Rickettsia infection benefits B. tabaci by improving the nutritional composition of its host, and also protects B. tabaci by enhancing its resistance towards insecticides (imidacloprid and spirotetramat), entomopathogenic fungi (A. attenuatus) and its main parasitoid (E. formosa); all of which could significantly impact on current management strategies.