Síntomas gastrointestinales, disfunción respiratoria, hepática y renal, principales factores asociados a letalidad por rickettsiosis trasmitida por garrapatas en Mexicali, Baja California, México / Gastrointestinal symptoms, respiratory, hepatic and renal dysfunction, main factors associated with lethality due to tickborne rickettsiosis in Mexicali, Baja California, Mexico

INTRODUCCIÓN: La rickettsiosis, enfermedad potencialmente mortal, es trasmitida por vectores como Rhipicephalus sanguineus, Dermacentor variabilis y D. andersonii, reservorios de Rickettsia rickettsii. En Baja California, México, es endémica, multifactorial, tiene alta letalidad, sus manifestaciones clínicas inespecíficas y ataque multisistémico dificultan el diagnóstico y tratamiento oportuno. OBJETIVO: Identificar los factores de riesgo asociados a la letalidad por rickettsiosis trasmitida por garrapatas en Mexicali, Baja California. PACIENTES Y MÉTODOS : Estudio observacional, analítico, transversal, retrospectivo, de 40 registros de pacientes con diagnóstico confirmado de rickettsiosis, periodo 2014 a 2018. Variables analizadas: sociodemográficas, clínicas, laboratorio clínico, evolución y desenlace. Se reportan frecuencias y medidas de asociación. RESULTADOS: 24 defunciones y 16 vivos. Más de 90% tuvo contacto conocido con garrapatas. Afectó en su mayoría a < 45 años en ambos grupos. La evolución antes del ingreso fue similar y la estancia hospitalaria fue mayor en los pacientes vivos (3,2 ± 4.7 vs 10,62 ± 7,6 p = 0,0002). Fiebre, cefalea, mialgias fueron predominantes. Datos asociados con letalidad: disfunción respiratoria (OR 38,33 IC95% 4,06-361,3 p < 0,0001), creatinina elevada (OR 15,4 IC95% 3,08-76,77 p < 0,0003), retardo del llenado capilar (OR 13,0 IC95% 2,73-61,78 p = 0,0005), dolor abdominal (OR 8,33, IC95% 1,90-36,44 p = 0,0029), AST (OR 7,5, IC95% 1,69-33,27 p = 0,005). CONCLUSIÓN: Esta enfermedad requiere de identificación temprana de factores que se asocian con letalidad para un tratamiento oportuno y adecuado.

BACKGROUND: Rickettsiosis, a potentially fatal disease, is transmitted by vectors such as Rhipicephalus sanguineus, Dermacentor variabilis and D. andersonii, reservoirs of Rickettsia rickettsii. In Baja California, Mexico, it is endemic, multifactorial, has high lethality, its nonspecific clinical manifestations and multisystem attack make diagnosis and timely treatment difficult. AIM: Identify the risk factors associated with lethality due to tick-transmitted rickettsiosis in Mexicali, Baja California. METHODS: Observational, analytical, cross-sectional, retrospective study of 40 records of patients with a confirmed diagnosis of rickettsiosis, period 2014 to 2018. Analyzed variables: sociodemographic, clinical, clinical laboratory, evolution and outcome. Frequencies and association measures are reported. RESULTS: 24 patients died and 16 survived. More than 90% had reported contact with ticks. It mostly affected ≤ 45 years in both groups. The evolution before admission was similar, and the hospital stay was longer in patients who lived (3.2 ± 4.7 vs 10.62 ± 7.6 p = 0.0002). Fever, headache, and myalgia are predominant. Data associated with lethality: respiratory dysfunction (OR 38.33 95% CI 4.06-361.3 p < 0.0001), elevated creatinine (OR 15.4 95% CI 3.08-76.77 p < 0.0003), delayed capillary refill (OR 13.0, 95% CI 2.73-61.78 p = 0.0005), abdominal pain (OR 8.33, 95% CI 1.90-36.44 p = 0.0029), AST (OR 7.5, 95% CI 1.69-33.27 p = 0.005). CONCLUSION: This disease requires early identification of factors that are associated with lethality for timely and adequate treatment.

Effect of forest fragmentation on tick infestations of birds and tick infection rates by rickettsia in the Atlantic forest of Brazil.

Habitat loss and modifications affect biodiversity, potentially contributing to outbreaks of infectious diseases. We evaluated if the patch sizeinfragmented areas of Atlantic Forest in southeastern Brazil influences the diversity of forest birds and consequently the prevalence of ticks on birds and the rickettsial infection of these ticks. During 2 years, we collected ticks from birds in 12 sites: four small forest patches (80-140 ha), four large ones (480-1,850 ha), and four forest control areas within the much larger Morro do Diabo State Park (approximately 36,000 ha). A total of 1,725 birds were captured (81 species, 24 families), from which 223 birds were infested by 2,339 ticks of the genus Amblyomma, mostly by the species A. nodosum. Bird diversity and richness were higher in larger than smaller forest fragments. The prevalence of ticks on birds was inversely correlated with bird diversity and richness. Among 174 A. nodosum tested for rickettsial infection by polymerase chain reaction, 51 were found to be infected by Rickettsia bellii or Rickettsia parkeri. However, tick infection rates by Rickettsia spp. were not statistically different between forest patch sizes. The higher prevalence of ticks on birds in degraded patches might be caused by a dominance of a few generalist bird species in small patches, allowing an easier transmission of parasites among individuals. It could also be related to more favorable microclimatic conditions for the free-living stages of A. nodosum in smaller forest fragments.The higher burden of ticks on birds in smaller forest fragments is an important secondary effect of habitat fragmentation, possibly increasing the likelihood of Rickettsia contagion.

Brazilian spotted fever: a case series from an endemic area in southeastern Brazil: clinical aspects.

This case series study is based on a retrospective review of medical records and case notification files of patients admitted to The Hospital das Clínicas da UNICAMP from 1985 to 2003 with a confirmed diagnosis of BSF either by fourfold rise in indirect immunofluorescence assay (IFA) titers of IgG antibodies reactive with R. rickettsii or isolation of R. rickettsii from blood or skin specimens. A median lethality of 41.9 % was observed between 1985 and 2004. The case-fatality ratio of 30 % in our study, lower than the overall São Paulo state ratio, could be explained by a higher index of suspicion and a larger experience in our hospital, a regional referral center for BSF. The presence of the classical triad of fever, rash, and headache as described in RMSF was observed in fever than half (35.2%) of our patients.

Rickettsia felis in Ctenocephalides spp. fleas, Brazil.

In June 2000, suspected cases of Brazilian spotted fever (BSF) occurred in Coronel Fabriciano Municipality, Minas Gerais State, Brazil. Pooled fleas collected near two fatal cases contained rickettsial DNA. The nucleotide sequence alignment of the 391-bp segment of the 17-kDa protein gene showed that the products were identical to each other and to the R. felis 17-kDa gene, confirming circulation of R. felis in Brazil.

An apparent outbreak of rickettsial illness in Costa Rica, 1974.

A focal outbreak of highly fatal disease occurred in eastern Costa Rica in 1974. No rickettsial spotted fevers have previously been reported in Costa Rica. Nevertheless, the available evidence points to an unidentified rickettsial pathogen, probably of the spotted fever group, as the agent responsible for this outbreak.