Rocky Mountain spotted fever, Colombia

Atypical Presentation of Rocky Mountain Spotted Fever in Pregnancy

Rocky Mountain spotted fever (RMSF) is a common tick-borne disease and can have variable presentation with potentially fatal outcomes when untreated. We describe an atypical presentation of RMSF in the third trimester. A 37-year-old multiparous woman at 31 0/7 weeks' gestation presented normotensive with headaches and fever but no rash or significant tick exposure. She was initially treated for atypical hemolysis, elevated liver enzymes, and low platelet count syndrome but further decompensated, requiring intensive care unit transfer, intubation, and emergent delivery. Doxycycline administration was associated with marked improvement with no significant sequalae to mother or infant. Later convalescent serologies were positive for RMSF. RMSF is a clinically challenging diagnosis in pregnancy. Given significant morbidity and mortality associated with delayed treatment, high suspicion in endemic areas is needed, and prompt antibiotic use with doxycycline should be administered.

Etiological characterization of acute undifferentiated febrile illness in Apartadó and Villeta municipalities, Colombia, during COVID-19 pandemic

Background

Acute undifferentiated febrile illness (AUFI) is one of the leading causes of illness in tropical regions. Although malaria is the most important cause, other pathogens such as Dengue (DENV), Leptospira and recently, Coronavirus Disease 2019 (COVID-19) have gained importance. In Colombia, few studies aimed to identify the etiology of AUFI. Most of them performed in Apartadó and Villeta municipalities, identifying the active circulation of several pathogens. Thus, we conducted a cross-sectional study in these municipalities to characterize the etiologies of AUFI during COVID-19 pandemic.

Methods

An active surveillance was conducted between September and December 2021 in local hospitals of Apartadó and Villeta municipalities. Febrile patients were enrolled after voluntarily agreeing to participate in the study. Ten different etiologies were evaluated through direct, serological, molecular and rapid diagnostic methods.

Results

In Apartadó a confirmed etiology was found in 60% of subjects, DENV (25%) being the most frequent, followed by leptospirosis (16.7%), malaria (10%), COVID-19 (8.3%), spotted fever group (SFG) rickettsiosis (6.7%) and Chikungunya (1.7%). In Villeta, a specific etiology was confirmed in 55.4% of patients, of which SFG rickettsiosis (39.3%) was the most frequent, followed by leptospirosis (21.4%), DENV (3.6%) and malaria (1.8%). No cases due to Mayaro, Yellow Fever, Oropouche and Venezuelan Equine Encephalitis viruses were detected.

Conclusion

We confirm the relevance of dengue fever, leptospirosis, SFG rickettsiosis, COVID-19 and malaria as causes of AUFI in the municipality of Apartadó, and highlight the great importance of SFG rickettsiosis as the main cause of AUFI in the municipality of Villeta.

Fatal acute undifferentiated febrile illness among clinically suspected leptospirosis cases in Colombia, 2016-2019

BACKGROUND

Acute undifferentiated febrile illness is a common challenge for clinicians, especially in tropical and subtropical countries. Incorrect or delayed diagnosis of febrile patients may result in medical complications or preventable deaths. Common causes of acute undifferentiated febrile illness in Colombia include leptospirosis, rickettsioses, dengue fever, malaria, chikungunya, and Zika virus infection. In this study, we described the acute undifferentiated febrile illness in postmortem patients reported as suspected cases of leptospirosis through the national leptospirosis surveillance in Colombia, 2016-2019.

METHODOLOGY/PRINCIPAL FINDINGS

We retrospectively analyze human fresh and formalin-fixed tissue samples from fatal suspected leptospirosis cases reported by the Public Health Laboratories in Colombia. Leptospirosis confirmation was made by immunohistochemistry, real-time polymerase chain reaction (PCR) in the tissue samples. In some cases, the serum sample was used for confirmation by Microagglutination test (MAT). Simultaneously, tissue samples were tested by PCR for the most common viral (dengue, Zika, and chikungunya), bacterial (Brucella spp., and Rickettsia spp.), and parasitic (malaria). Fresh tissue samples from 92 fatal suspected leptospirosis cases were reported to the National Reference Laboratory from 22/32 departments in Colombia. We confirmed leptospirosis in 27% (25/92) of cases. Other pathogens identified by real-time PCR were Brucella spp. (10.9%), Rickettsia spp. (14.1%), and dengue (2.2%). Dengue (6.9%), hepatitis (3.5%), and Yellow Fever cases (2.2%) were detected by the pathology. All patients were negative for chikungunya and Plasmodium spp. Most cases were classified as undifferentiated febrile illnesses (45.7%; 42/92).

CONCLUSIONS/SIGNIFICANCE

This study underscores the importance of early and accurate recognition of leptospirosis to prevent mortalities. Moreover, it draws attention to the existence of other febrile syndromes in Colombia, including rickettsiosis and brucellosis, that currently lack sufficient human surveillance and regular reporting. Expanding laboratory surveillance to include viruses such as Hantavirus, Mayaro virus, Oropouche virus, and West Nile virus is crucial.

Etiologies of Zoonotic Tropical Febrile Illnesses That Are Not Part of the Notifiable Diseases in Colombia

In Colombia, tropical febrile illnesses represent one of the most important causes of clinical attention. Febrile illnesses in the tropics are mainly zoonotic and have a broad etiology. The Colombian surveillance system monitors some notifiable diseases. However, several etiologies are not monitored by this system. In the present review, we describe eleven different etiologies of zoonotic tropical febrile illnesses that are not monitored by the Colombian surveillance system but have scientific, historical, and contemporary data that confirm or suggest their presence in different regions of the country: Anaplasma, Arenavirus, Bartonella, relapsing fever group Borrelia, Coxiella burnetii, Ehrlichia, Hantavirus, Mayaro virus, Orientia, Oropouche virus, and Rickettsia. These could generate a risk for the local population, travelers, and immigrants, due to which they should be included in the mandatory notification system, considering their importance for Colombian public health.

Molecular detection of tick-borne rickettsial pathogens in ticks collected from domestic animals from Cauca, Colombia

Some hard ticks' species can act as vectors of a wide variety of pathogens of human and animal importance such as Anaplasma, Ehrlichia and Rickettsia spp. In Colombia, a total of forty-six tick species have been described, and some of them have been implicated as vectors of some infectious agents. The department of Cauca is one of the thirty-two departments of Colombia. Most of its population lives in rural areas and depends on agriculture as the main economic activity, favoring exposure to ticks and tick-borne pathogens. Thus, the present study aimed to determine the tick species and tick-borne pathogens circulating in this region. From August to November 2017, ticks were collected from dogs, horses and cattle from eight rural areas of four municipalities in the department of Cauca. All collected ticks were classified according to taxonomic keys and organized in pools. DNA was extracted from all tick pools for molecular confirmation of tick species and detection of Anaplasma, Ehrlichia and Rickettsia spp. A total of 2809 ticks were collected which were grouped in 602 pools. Ticks were morphologically identified as Amblyomma cajennense sensu lato, Dermacentor nitens, Rhipicephalus microplus and Rhipicephalus sanguineus sensu lato. The molecular identity of A. cajennense s.l. was confirmed as Amblyomma patinoi. A total of 95% of the pools scored positive for members of the Anaplasmataceae family, of which, 7.8% and 7.3% were positive to Anaplasma and Ehrlichia spp., respectively, being identified as Anaplasma marginale, Ehrlichia minasensis and Ehrlichia canis; and 16.1% were positive for Rickettsia spp. with high identity for Rickettsia asembonensis, Rickettsia felis and Candidatus Rickettsia senegalensis. This is the first report describing the natural infection of ticks with rickettsial pathogens and the occurrence of A. patinoi ticks in Cauca department, Colombia.

Clinical manifestations of Rickettsia rickettsii in a familial outbreak in Panama

We report an isolated outbreak of Rickettsia rickettsii in the Ngäbe-Buglé indigenous region, located 750 m (tropical wet) above sea level, in a jungle and mountainous area of Western Panama. Seven members of a family were infected simultaneously, resulting in four deaths. Family outbreaks have been previously described and are responsible for 4-8% of the cases described [1-4]. The simultaneous onset of symptoms in the affected population group is extremely unusual [1,5], but it should not dissuade the clinician from considering the possibility of Rickettsia rickettsii infection.

A Vaccine for Canine Rocky Mountain Spotted Fever: An Unmet One Health Need

Outbreaks of life-threatening Rocky Mountain spotted fever in humans and dogs associated with a canine-tick maintenance cycle constitute an important One Health opportunity. The reality of the problem has been observed strikingly in Mexico, Brazil, Colombia, and Native American tribal lands in Arizona. The brown dog tick, Rhipicephalus sanguineus sensu lato, acquires the rickettsia from bacteremic dogs and can maintain the bacterium transtadially to the next tick stage. The subsequent adult tick can then transmit infection to a new host, as shown by guinea pig models. These brown dog ticks maintain spotted fever group rickettsiae transovarially through many generations, thus serving as both vector and reservoir. Vaccine containing whole-killed R. rickettsii does not stimulate sufficient immunity. Studies of Rickettsia subunit antigens have demonstrated that conformationally preserved outer-membrane autotransporter proteins A and B are the leading vaccine candidates. The possibility of a potentially safe and effective live attenuated vaccine has only begun to be explored as gene knockout methods are applied to these obligately intracellular pathogens.

Frequency of antibodies and seroconversion against Rickettsia spp in patients consulting health institutions in the department of Caldas, Colombia, 2016-2019

Introduction: Rickettsioses are zoonotic diseases transmitted by arthropods acting as vectors and reservoirs. Disease symptoms are nonspecific and, therefore, their clinical diagnosis is difficult. Indirect immunofluorescence (IFA) is the gold standard assay for diagnosis. The interest for conducting studies on these pathologies has resurfaced in Colombia since 2001; besides, previous studies have evidenced cases of rickettsiosis in the north of the department of Caldas. Objective: To establish the frequency of antibodies and seroconversion against Rickettsia spp. In patients consulting health institutions in Caldas, Colombia, from 2016 to 2019. Materials and methods: We conducted a quantitative, observational, and descriptive study on a non-probabilistic sample of 175 patients with symptoms compatible with rickettsiosis who consulted in different municipalities of Caldas, Colombia; IFA was performed to detect antibodies in the acute and convalescent phases against Rickettsia rickettsii, Rickettsia typhi, and Rickettsia felis. Results: The average age of the patients was 31 years. The municipalities with the highest proportion of seropositive cases were Belalcázar, Chinchiná, Filadelfia, La Dorada, La Merced, and Manizales; 66% of patients owned pets and 12% reported arthropod bites. The most frequent signs and symptoms were headache (69.7%), arthromyalgia (60%), and fever (58.2%). IgG seroprevalence was 60% for R. rickettsii, 47.9% for R. typhi, and, and 24% for R. felis. Eight patients presented seroconversion. Conclusion: We found evidence of the circulation of Rickettsia species from the spotted fever group and the typhus group associated with human cases in Caldas.

Experimental infection and vector competence of Amblyomma patinoi, a member of the Amblyomma cajennense species complex, for the human pathogen Rickettsia rickettsii

Amblyomma patinoi ticks infected with Rickettsia rickettsii are present in Colombia, but its vector competence is unknown. Hence, we evaluated the vector competence of A. patinoi with R. rickettsii under laboratory conditions. Experimental guinea pigs and rabbits (males and females) were separated in the infected group (IG) and the control group (CG). In the IG, the filial 1 (F1) larvae (R. rickettsii-free) from Colombian A. patinoi engorged female specimens were exposed to R. rickettsii (ITU strain) by feeding on infected guinea pigs. Next, F1 nymphs and adults, and F2 larvae were allowed to feed on uninfected guinea pigs or rabbits and tested by qPCR targeting the gltA rickettsial gene. All animals used to feed the IG F1 ticks became febrile and had R. rickettsii infection (89% fatality rate) detected through serological or molecular techniques. After the F1 larvae ticks became R. rickettsii infected, subsequent IG tick stages were able to maintain the rickettsial infection by transstadial maintenance to all infested animals, indicating A. patinoi vector competence. Subsequently, almost 31% of the F1 female egg masses and only 42% of their F2 larvae were infected. Less than 50% of the infected females transmitted R. rickettsii transovarially, and only a part of the offspring were infected. This study demonstrated that A. patinoi might not be able to sustain R. rickettsii infection by transovarial transmission for successive tick generations without horizontal transmission via rickettsemic hosts. This condition might result in low R. rickettsii-infection rates of A. patinoi under natural conditions.

Rickettsia parkeri strain Atlantic rainforest in ticks (Acari: Ixodidae) of wild birds in Arauca, Orinoquia region of Colombia

Birds are important hosts for the development of the immature stages of several tick species that are vectors for disease-causing microorganisms in animals and humans. Colombia has the highest number of bird species worldwide; however, there is scarce data on the role of birds in the circulation of ticks and their associated pathogens, such as rickettsiae. The department of Arauca has a high diversity of resident and migratory (boreal and austral) birds and ticks associated with the transmission of Rickettsia. The objective of this research was to identify tick species parasitizing birds and to detect Rickettsia species in these ectoparasites. We conducted samplings in the municipalities of Arauca, Cravo Norte, and Tame between November of 2018 and August of 2019. Birds were captured using mist nets and examined for the presence of tick species. The collected ticks were morphologically and molecularly identified. Furthermore, we detected rickettsiae in ticks by amplifying fragments of the citrate synthase (gltA) and outer membrane protein (ompB) genes. We captured 606 birds belonging to 25 families and 115 species. Tick infestation rate was 3.3% (20/606) in the birds captured and eight new associations between wild birds and ticks are reported for the American continent. We identified four tick species: Amblyomma nodosum, Amblyomma longirostre, Amblyomma mixtum, and Amblyomma sp.. Moreover, we confirmed the presence of Rickettsia parkeri strain Atlantic rainforest in A. nodosum, a medically-relevant rickettsia due to cases of rickettsiosis in the American continent. This finding manifests the importance of wild birds as hosts and dispersal agents of ticks infected with pathogenic rickettsiae, as well as the need to monitor migratory birds in the Orinoquia and other regions of Colombia and America.

The neglected challenge: Vaccination against rickettsiae

Over the last decades, rickettsioses are emerging worldwide. These diseases are caused by intracellular bacteria. Although rickettsioses can be treated with antibiotics, a vaccine against rickettsiae is highly desired for several reasons. Rickettsioses are highly prevalent, especially in poor countries, and there are indications of the development of antibiotic resistance. In addition, some rickettsiae can persist and cause recurrent disease. The development of a vaccine requires the understanding of the immune mechanisms that are involved in protection as well as in immunopathology. Knowledge about these immune responses is accumulating, and efforts have been undertaken to identify antigenic components of rickettsiae that may be useful as a vaccine. This review provides an overview on current knowledge of adaptive immunity against rickettsiae, which is essential for defense, rickettsial antigens that have been identified so far, and on vaccination strategies that have been used in animal models of rickettsial infections.

Tickbite-associated chronic pruritic lesions in an Afro-descendant population in the Cauca Department, Colombia. I. Clinical features and impact on health

BACKGROUND

During a health survey in a remote area in southwest Colombia, it became apparent that a high percentage of the population suffered from chronic pruritus in association with high numbers of ticks and tickbites.

OBJECTIVE

To determine the clinical features and severity of tickbite-associated pruritus.

METHOD

At twotime points - 8 weeks apart to account for seasonal effects - a cross-sectional study was conducted encompassing physical examination of the population, histological analysis of skin biopsies, and determining serum for antibodies against spotted fever (SFG) rickettsiae and typhus group (TG) rickettsiae. Ticks were identified using morphological criteria, and infection by rickettsiae was determined by PCR.

RESULTS

About 94.5% of the population (95% CI 92-97%) showed clinical signs of a pruritic arthropod reaction and of chronic pruritus with lichenoid papules and hyper- and hypopigmented nodules on otherwise noninflamed skin. Pruritus markedly impaired the quality of life in terms of sleeping disturbances. No signs for other diseases were observed. Chronic pruritus appeared to be because of repeated tickbites and scratching, but not because of other dermatological or medical conditions. Antibodies against SFG and TG-rickettsiae were detected at 79.0% (95% CI 73-86) and 3.6% (95% CI 0.7-6), respectively. Ticks were identified as Amblyomma cajennense.

CONCLUSION

Remarkably high exposure to tick bites caused an unusually high rate of acute and chronic pruritus and markedly impaired quality of life of the investigated rural community. This underlines the necessity of public health measures and surveillance of rickettsial disease.

Detection of tick-borne rickettsial pathogens in naturally infected dogs and dog-associated ticks in Medellin, Colombia

Tick-borne rickettsial pathogens (TBRP) are important causes of infections in both dogs and humans. Dogs play an important role as a biological host for several tick species and can serve as sentinels for rickettsial infections. Our aim was to determine the presence of TBRP in dogs and in dog-associated ticks and their potential risk to human diseases in Medellin, Colombia. DNA for E. canis (16S rRNA and dsb) and A. platys (groEl) was detected in 17.6% (53/300) and 2.6% (8/300) of dogs, respectively. Antibodies against Ehrlichia spp. 82 (27.3%) and Anaplasma spp. 8 (2.6%) were detected in dogs. Antibody reactivity against both agents were found in 16 dogs (5.3%). Eight dogs showed antibody for Rickettsia spp. with titers that suggest 3 of them had a probable exposure to R. parkeri. Rhipicephalus sanguineus s.l. (178/193) was the main tick in dogs, followed by R. microplus (15/193). The minimum infection rates (MIR) in R. sanguineus were 11.8% for E. canis and 3.4% for A. platys. E. canis and A. platys are the main TBRP infecting dogs and ticks and R. sanguineus s.l. is likely involved in the transmission of both agents. Interestingly, we found serological evidence of exposure in dogs for spotted fever group rickettsiae.

Germ cells: a useful tool for the taxonomy of Rhipicephalus sanguineus s.l. and species of the Amblyomma cajennense complex (Acari: Ixodidae)

The systematics of several ticks species (Acari: Ixodidae) remains controversial. Many species, including those of the Amblyomma cajennense complex and Rhipicephalus sanguineus s.l., are given special attention since they are cryptic species complexes and are also important in human and veterinary medicine. The A. cajennense complex was recently reorganized into six valid species, among which Amblyomma patinoi and Amblyomma mixtum have been confirmed in Colombia. On the other hand, the taxonomic status of R. sanguineus s.l. is controversial since it is a cosmopolitan cryptic species complex with a high reproductive capacity and a broad range of hosts (including man). To address this challenge, the germ cells of male ticks display a diverse morphology that offers novel opportunities for taxonomy. This study describes the events of spermatogenesis in A. mixtum and R. sanguineus s.l. individuals collected during active feeding on domestic hosts in the department of Caldas, Colombia. The individuals were identified using dichotomous keys and through PCR amplification of a fragment of the mitochondrial 16S ribosomal DNA gene. The male reproductive systems of A. mixtum and R. sanguineus s.l. were fixed in 2.5% glutaraldehyde for 48 h and dehydrated in increasing dilutions of ethanol. The samples were then embedded and mounted in historesin to obtain sections of 3 μm that were stained with hematoxylin-eosin (HE), photographed, and visualized through optical microscopy. The results show that the morphology of mature germ cells displays excellent diagnostic traits that can be used for tick taxonomy.

A Cluster of Cases of Rocky Mountain Spotted Fever in an Area Of Colombia Not Known to be Endemic for This Disease

Rocky Mountain spotted fever (RMSF) has been reported in Colombia since 1937. Most recent outbreaks were in 2006-2008, followed by the absence of recognized cases. This report describes new clinical cases of RMSF and epidemiologic investigations. Medical records were reviewed, and fieldwork, serological and molecular diagnostic testing, and bacterial isolation were performed. Fever, hypotension, abdominal discomfort, and rash accompanied by thrombocytopenia and leukopenia were the most characteristic manifestations. Two convalescent sera from the index case and sera from two dogs revealed high anti-spotted fever group Rickettsia antibody titers. Rickettsia rickettsii was isolated from case 4. Cases 2 and 3 were identified by epidemiological connection with the index case. Thus, a new cluster of cases of RMSF was identified in Antioquia, Colombia, with the occurrence of fatal cases, which indicates the active circulation of the bacteria and a potential risk for the population.

Infección y enfermedad por Rickettsia spp. del grupo de las fiebres manchadas en pacientes febriles del Urabá antioqueño, Colombia

Objetivo: determinar la frecuencia de la infección y enfermedad por Rickettsia spp. del grupo de las fiebres manchadas en pacientes febriles del Urabá antioqueño, que asistieron a centros hospitalarios de la región.Métodos: se incluyeron en el estudio pacientes febriles provenientes de 9 instituciones de salud de la región del Urabá, los cuales fueron encuestados para determinar sus variables clínicas y demográficas. De estos pacientes se obtuvieron muestras de suero durante las fases aguda y convaleciente de la enfermedad. Para cada muestra se determinó la seropositividad (título ≥ 64) y su título de anticuerpos seriados dobles mediante inmunofluorescencia indirecta para IgG contra el antígeno de Rickettsia rickettsii.Resultados: se analizaron 89 pacientes febriles con 89 muestras de fase aguda y 60 en fase convaleciente. Los síntomas más comunes de los pacientes fueron cefalea, ictericia, mialgias, náuseas, dolor abdominal, trombocitopenia y vómito. El 55,1 % de los pacientes provenía de áreas rurales. Se obtuvo seropositividad del 40,4 % con títulos entre 64-512, infección previa en un 33,7 % y rickettsiosis en 6 pacientes (6,7 %). Los pacientes con seroconversión o serorefuerzo provenían de los municipios de Apartadó (n = 2), Chigorodó (n = 1), Necoclí (n = 2) y Turbo (n = 1); el hallazgo clínico más destacado fue la trombocitopenia.Conclusiones: se demostró que la infección y la enfermedad rickettsial continúan siendo activas en la zona del Urabá. Este hallazgo permite alertar a las autoridades de salud de la región para que se brinde tratamiento con antibióticos a los casos sospechosos de manera temprana y de esta forma evitar las muertes o secuelas derivadas de este tipo de infecciones.

Fatal Rickettsia rickettsii infection in a child, Northwestern Colombia, 2017

This report describes a new lethal case of Rickettsia rickettsii infection in a child from Northwestern Colombia, after ten years of the last outbreaks in the same region. Colombian public-health authorities should consider to include this severe rickettsiosis in the compulsory-reporting diseases, with the aim of knowing its burden in the country.

Epidemiological characterization of incident cases of Rickettsia infection in rural areas of Urabá region, Colombia

Introduction

Most of the studies related to rickettsial infection in Colombia are cross-sectional because of the challenge in conducting prospective studies on infectious disease that may have a difficult diagnosis. Although cross-sectional studies are essential to detect people exposed to rickettsiae, they are not suited to demonstrate the recent circulation of this pathogen in areas at risk of transmission.

Objective

To characterize the epidemiology of incident cases of Spotted fever group (SFG) rickettsial infection in humans and equines from rural areas of Urabá region in Colombia where outbreaks of rickettsiae previously occurred.

Materials and methods

A prospective study was conducted in the Alto de Mulatos and Las Changas in the Urabá region. Serum samples and socio-ecological information were collected from 597 people enrolled in 2015, and a second sample was collected from 273 people a year later. Indirect immune-fluorescence assays for detection of IgG antibody against rickettsiae were done using slides with Rickettsia rickettsii antigens. A titer ≥128 was considered positive. Incident cases were defined as (i) serological conversion of IgG titers from seronegative to seropositive or (ii) at least a four-fold increase in IgG end point titers in the second sample.

Results

The cumulative incidence of rickettsial infection was 6.23% (95%CI 3.67–9.78) in humans and 32.31% (21/65) of incident cases in equines. Incident cases were mostly females (82.35%), the median age of cases was 41.02 years (IQR 18.62–54.1), and 29.41% reported tick bites during the study period. Results from multivariate analysis showed that removal of ticks after working outdoors is a protective factor for rickettsial infection (RR 0.26, 95%CI 0.08–0.84) and that a higher incidence of infection occurred in people who reported fever in the last year (RR 4.26, 95%CI 1.15–9.31).

Conclusions

These results showed recent circulation of SFG rickettsiae in areas where previous lethal outbreaks have been reported, supporting the implementation of preventive measures to halt rickettsial transmission in the studied communities.

On the northwestern coast of Colombia three lethal outbreaks of rickettsioses caused by the species Rickettsia rickettsii have been reported. The lack of an active epidemiological surveillance system in these areas makes difficult the detection and the timely treatment of the disease prompting a worse prognosis. In this study, new cases of rickettsial infection were detected in people and horses living in areas where outbreaks of the disease occurred in the previous decade. In addition, the results showed that nonspecific febrile syndromes are associated to rickettsial infection and protective measures such as tick removal from the body decrease the risk of infection. The design, evaluation and implementation of a surveillance program of emerging and re-emerging infectious diseases, such as rickettsioses, should be a priority in the country, especially in areas where such infections have proved to be lethal.

Modelos potenciales de distribución geográfica y climática del complejo Amblyomma cajennense (Acari: Ixodidae), potencial vector de Rickettsia rickettsii en Colombia

Introducción. Especies del complejo A. cajennense, potenciales vectores implicados en la transmisión de Rickettsia rickettsii en Centro y Suramérica, presentan una amplia distribución geográfica en el Neotrópico. En Colombia el conocimiento sobre las especies de este complejo, su distribución y aspectos de su ecología es incipiente.Objetivo. Explorar la ecología del complejo A. cajennense en Colombia a partir del estudio de su selección de hábitat y la generación de modelos potenciales de distribución geográfica y climática.Materiales y métodos. Registros únicos de presencia de estas garrapatas fueron utilizados en el estudio de patrones de selección del hábitat mediante ENFA y se construyeron modelos de distribución potencial con las metodologías MaxEnt y GARP.Resultados. El complejo A. cajennense se encontró en las cinco regiones naturales de Colombia con 64,71% de los registros procedentes de los departamentos de Antioquia, Cundinamarca y Huila. La selección del hábitat muestra que estas garrapatas seleccionan fuertemente las áreas geográficas (ENFA: 96,03%) de acuerdo con condiciones de isotermalidad y precipitación del trimestre más seco del año. Los modelos de distribución potencial indican idoneidad de hábitat en 31-51% del área del país, dependiendo del algoritmo empleado.Conclusiones. El complejo A. cajennense en Colombia presenta una distribución altamente influenciada por comportamiento de selección del hábitat climático; esta característica facilitó la creación de modelos de distribución. Estudios de campo permitirán validar los modelos presentados y otros estudios genéticos son requeridos en el país para la identificación de especies del complejo y el abordaje de potenciales zonas de hibridación de estas especies.

Detection of Rickettsia spp. in ticks (Acari: Ixodidae) of domestic animals in Colombia

Rickettsiosis are emerging or re-emerging diseases, with a worldwide distribution associated to transmission by arthropod vectors. Rickettsia species belong to the spotted fever group (SFG) and are transmitted by hard ticks (Acari: Ixodidae) that may act as vectors and reservoirs. This study carried out a molecular detection of Rickettsia from 7 species of the family Ixodidae collected from domestic hosts by PCR amplification of fragments of the citrate synthase "gltA" gene and outer membrane protein "ompA" gene. Of the 204 samples analyzed, 11.3% (23) were positive for rickettsial infection. Three Rickettsia species belonging to the SFG were found, constituting the first reports of Rickettsia rickettsii in 2 departments of Colombia. Furthermore, we confirmed the first occurrence of Candidatus Rickettsia andeanae in Colombia, a species with an unknown pathogenic role in humans. These results raise awareness regarding the need to increase epidemiological control measures, as well as to consider new endemic regions in Colombia for Rocky Mountain spotted fever (RMSF).

Rickettsial infection in ticks (Acari: Ixodidae) from reptiles in the Colombian Caribbean

Although more reptiles are illegally traded in Colombia than any other group of animals, for both local and international markets, little is known about ticks associated with reptiles or pathogens associated with these ticks. In this study, ticks were collected from reptiles in Magdalena, Cesar and La Guajira regions in northern Colombia, and identified morphologically using taxonomic keys and molecularly by sequencing of the COI gene. In addition, Rickettsia spp. were detected by PCR amplifying the gltA, 16S rRNA, and sca1 genes. Ticks were identified as Amblyomma dissimile, representing the first record for this species in 17 of the 26 species of reptiles sampled. Additionally, our data expand the distribution range for this tick in Colombia. Rickettsia spp. DNA was detected in 18 ticks (3.6%) from 16 reptiles. Sequence analyses indicated that most of the Rickettsia were members of the R. monacensis clade, most closely related to Rickettsia sp. strain Colombianensi. We detected one tick infected with a Rickettsia with 99% identity to R. bellii.

Epidemiology of Spotted Fever Group Rickettsioses and Acute Undifferentiated Febrile Illness in Villeta, Colombia

Etiology of acute undifferentiated febrile syndrome (AUFS) is often unknown, leading to inaccurate diagnosis and treatment. Villeta town has been identified as an endemic area for spotted fever group (SFG) rickettsioses but little is known about possible amplifier hosts and other Rickettsia species different from Rickettsia rickettsii. Besides, few studies have approached other AUFS etiologies in the region. We investigated the role of dengue, leptospirosis, rickettsioses, human anaplasmosis, and Q fever as possible causes of AUFS in patients from Villeta. Sera specimens and ticks from animals as well as ticks from vegetation were studied for the presence of different Rickettsia spp. Among 104 sera from patients with AUFS, 16.4%, 24.0%, and 2.9% patients seroconverted to dengue, Leptospira, and SFG Rickettsia, respectively, with a case of probable coinfection or cross-reaction with Anaplasma phagocytophilum. None of the samples were reactive for Coxiella burnetii. Sera samples from 74 horses, 118 dogs, and 62 bovines were collected and showed 33.8%, 14.4%, and 50.0% of seroprevalence for SFG Rickettsia, respectively. A total of 1,287 ixodid ticks were collected from animals/vegetation and processed in pools for polymerase chain reaction. Among them, 1.7% was positive for Rickettsia genes, and Rickettsia amblyommii, R. rickettsii, and Rickettsia spp. were found. These results confirm the circulation of dengue, different SFG Rickettsia species and the relevance of other etiologies like leptospirosis and human anaplasmosis. Further studies must identify different epidemiological variables to establish proper surveillance and control programs.

Rocky Mountain Spotted Fever and Pregnancy: Four Cases from Sonora, Mexico

We present a series of four pregnant women with Rocky Mountain spotted fever (RMSF) that occurred in Sonora, Mexico, during 2015-2016. Confirmatory diagnoses were made by polymerase chain reaction or serological reactivity to antigens of Rickettsia rickettsii by using an indirect immunofluorescence antibody assay. Each patient presented with fever and petechial rash and was treated successfully with doxycycline. Each of the women and one full-term infant delivered at 36 weeks gestation survived the infection. Three of the patients in their first trimester of pregnancy suffered spontaneous abortions. RMSF should be suspected in any pregnant woman presenting with fever, malaise and rash in regions where R. rickettsii is endemic.

Probable case of spotted fever group rickettsial infection in a new suspected endemic area, Colombia

Spoted fever group (SFG) rickettsioses are actually considered as emerging and re-emerging zoonotic diseases, caused by pathogenic bacteria of the spotted fever group rickettsiae (SFGR). Recently, serologic studies in human and animals conducted in Colombian Orinoquia, showed a high seroprevalence against SFGR. In June 2015, a 50-year-old male was admitted to a hospital in Bogotá, Colombia, with two days of malaise and temperature of 39°C, associated to generalized rash 24h after the onset of fever. He referred a work visit and outdoor activities in rural area of the Department of Meta 15days prior the onset of symptoms. The patient was transferred to the intensive care unit with supplementary oxygen, inotropic support and was assessed by the infectious diseases department, indicating the addition of Doxycycline. After seven days of antibiotic treatment the patient was discharged with no evidence of new symptoms or sequels. Retrospectively, two serum samples collected during the acute and convalescent phase were evaluated; there was four fold rise in titer against SFGR. With the foregoing, associated with the recent serological evidence that suggests the circulation of SFGR species in the Colombian Orinoquia, we consider to recognize this region as a new endemic area for SFG Rickettsioses.

Presence of Aedes (Stegomyia) aegypti (Linnaeus, 1762) and its natural infection with dengue virus at unrecorded heights in Colombia

INTRODUCTION

Aedes aegypti is the main vector of urban yellow fever, dengue, chikungunya and Zika viruses. The biogeographical distribution of this species has expanded due to global warming, and socioeconomic and cultural factors. The changes in the altitudinal distribution patterns of this vector and its natural infection are priority fields of research to develop entomological, virological and public health surveillance strategies. 

OBJECTIVE

To evaluate the presence of A. aegypti and its natural infection with dengue virus in altitudes above 1.800 meters above sea level in two peripheral municipalities of the Valle de Aburrá, Antioquia, Colombia. 

MATERIALS AND METHODS

Twenty-one ovitraps were set in the municipalities of Bello and San Pedro de los Milagros, at altitudes ranging from 1.882 to 2.659 masl. Emerged adults caught in the ovitraps were tested by RT-PCR for dengue virus detection. 

RESULTS

We collected 367 A. aegypti adults, seven of which were found as high as 2.302 masl in Tierradentro, Bello. We detected serotype 2 dengue infection in 12 A. aegypti specimens collected in the neighbourhood of París, in Bello, at 1.984 masl. 

CONCLUSION

We recorded A. aegypti at 2.302 masl, so far the highest altitudinal record in Colombia for this vector. Furthermore, mosquitoes collected at 1.984 masl were positive for dengue virus. These findings are significant as they identify regions in Colombia at risk of potential autochthonous transmission of dengue and other arboviruses by A. aegypti.

Diagnosis and Management of Tickborne Rickettsial Diseases: Rocky Mountain Spotted Fever and Other Spotted Fever Group Rickettsioses, Ehrlichioses, and Anaplasmosis - United States

Tickborne rickettsial diseases continue to cause severe illness and death in otherwise healthy adults and children, despite the availability of low-cost, effective antibacterial therapy. Recognition early in the clinical course is critical because this is the period when antibacterial therapy is most effective. Early signs and symptoms of these illnesses are nonspecific or mimic other illnesses, which can make diagnosis challenging. Previously undescribed tickborne rickettsial diseases continue to be recognized, and since 2004, three additional agents have been described as causes of human disease in the United States: Rickettsia parkeri, Ehrlichia muris-like agent, and Rickettsia species 364D. This report updates the 2006 CDC recommendations on the diagnosis and management of tickborne rickettsial diseases in the United States and includes information on the practical aspects of epidemiology, clinical assessment, treatment, laboratory diagnosis, and prevention of tickborne rickettsial diseases. The CDC Rickettsial Zoonoses Branch, in consultation with external clinical and academic specialists and public health professionals, developed this report to assist health care providers and public health professionals to 1) recognize key epidemiologic features and clinical manifestations of tickborne rickettsial diseases, 2) recognize that doxycycline is the treatment of choice for suspected tickborne rickettsial diseases in adults and children, 3) understand that early empiric antibacterial therapy can prevent severe disease and death, 4) request the appropriate confirmatory diagnostic tests and understand their usefulness and limitations, and 5) report probable and confirmed cases of tickborne rickettsial diseases to public health authorities.

CONTRIBUTIONS TO RICKETTSIOSES RESEARCH IN COLOMBIA (1917-1943), LUIS B. PATIÑO CAMARGO

Colombian physician Luis Benigno Patiño Camargo was one of the pioneers in the study of rickettsioses in South America, demonstrating for the first time in Colombia the presence of Rickettsia rickettsii as the etiological agent of a highly deadly exanthematic febrile syndrome in the 1930s. However, Patiño-Camargo performed other investigations from 1917-1943, which represent the first descriptions and scientific evidence of the presence of R. prowazekii and R. typhi in Colombia. Almost 60 years after the latest research conducted by Dr. Patiño-Camargo, rickettsioses were again a matter of interest and research. In the last decade over 20 research studies have been published, showing new endemic areas for R. rickettsii, as well as the description of new rickettsial species in Colombia.

Molecular Evidence of Different Rickettsia Species in Villeta, Colombia

The aim of this work was to detect and identify Rickettsia species in ticks collected in rural areas of Villeta, Colombia. Tick specimens were collected from domestic animals and walls of houses in five rural villages of Villeta town and from humans in Naranjal village (same town). Moreover, a flea collected from the same area was also processed. DNA was extracted and tested by conventional, semi-nested, and nested PCR reactions targeting rickettsial genes. In the ticks collected from humans from Naranjal village, a nymph of Amblyomma cajennense sensu lato was amplified using primers for ompA and sequenced (100% identity with "Candidatus Rickettsia amblyommii"). Last, three amplicons from the Ctenocephalides felis flea, corresponding to gltA, ompB, and 16S rRNA genes, showed high identity with R. felis (98.5%, 97.3%, and 99.2%, respectively) and "Candidatus Rickettsia asemboensis" (99.7% and 100%, respectively). To our knowledge, these results correspond to the first molecular detection in Colombia of "Candidatus Rickettsia amblyommii" and "Ca. Rickettsia asemboensis" in fleas.

Genetic identification of rickettsial isolates from fatal cases of Brazilian spotted fever and comparison with Rickettsia rickettsii isolates from the American continents

Fifteen bacterial isolates from spotted fever group rickettsiosis in Brazil were genetically identified as Rickettsia rickettsii. In a phylogenetic analysis with other R. rickettsii isolates from GenBank, the Central/South American isolates showed low polymorphism and formed a clade distinct from two North American clades, with the North American clades having greater in-branch polymorphism.

Infection of Amblyomma ovale by Rickettsia sp. strain Atlantic rainforest, Colombia

Our goal was to understand rickettsial spotted fevers' circulation in areas of previous outbreaks reported from 2006 to 2008 in Colombia. We herein present molecular identification and isolation of Rickettsia sp. Atlantic rainforest strain from Amblyomma ovale ticks, a strain shown to be pathogenic to humans. Infected ticks were found on dogs and a rodent in Antioquia and Córdoba Provinces. This is the first report of this rickettsia outside Brazil, which expands its known range considerably.

Rickettsial infection in Amblyomma cajennense ticks and capybaras (Hydrochoerus hydrochaeris) in a Brazilian spotted fever-endemic area

BACKGROUND

Brazilian spotted fever (BSF), caused by the bacterium Rickettsia rickettsii, is the deadliest spotted fever of the world. In most of the BSF-endemic areas, capybaras (Hydrochoerus hydrochaeris) are the principal host for the tick Amblyomma cajennense, which is the main vector of BSF.

METHODS

In 2012, a BSF case was confirmed in a child that was bitten by ticks in a residential park area inhabited by A. cajennense-infested capybaras in Itú municipality, southeastern Brazil. Host questing A. cajennense adult ticks were collected in the residential park and brought alive to the laboratory, where they were macerated and intraperitoneally inoculated into guinea pigs. A tick-inoculated guinea pig that presented high fever was euthanized and its internal organs were macerated and inoculated into additional guinea pigs (guinea pig passage). Tissue samples from guinea pig passages were also used to inoculate Vero cells through the shell vial technique. Infected cells were used for molecular characterization of the rickettsial isolate through PCR and DNA sequencing of fragments of three rickettsial genes (gltA, ompA, and ompB). Blood serum samples were collected from 172 capybaras that inhabited the residential park. Sera were tested through the immunofluorescence assay using R. rickettsii antigen.

RESULTS

A tick-inoculated guinea pig presented high fever accompanied by scrotal reactions (edema and marked redness). These signs were reproduced by consecutive guinea pig passages. Rickettsia was successfully isolated in Vero cells that were inoculated with brain homogenate derived from a 3rd passage-febrile guinea pig. Molecular characterization of this rickettsial isolate (designated as strain ITU) yielded DNA sequences that were all 100% identical to corresponding sequences of R. rickettsii in Genbank. A total of 83 (48.3%) out of 172 capybaras were seroreactive to R. rickettsii, with endpoint titers ranging from 64 to 8192.

CONCLUSIONS

A viable isolate of R. rickettsii was obtained from the tick A. cajennense, comprising the first viable R. rickettsi isolate from this tick species during the last 60 years. Nearly half of the capybara population of the residential park was seroreactive to R. rickettsii, corroborating the findings that the local A. cajennense population was infected by R. rickettsii.

Update on tick-borne rickettsioses around the world: a geographic approach

Tick-borne rickettsioses are caused by obligate intracellular bacteria belonging to the spotted fever group of the genus Rickettsia. These zoonoses are among the oldest known vector-borne diseases. However, in the past 25 years, the scope and importance of the recognized tick-associated rickettsial pathogens have increased dramatically, making this complex of diseases an ideal paradigm for the understanding of emerging and reemerging infections. Several species of tick-borne rickettsiae that were considered nonpathogenic for decades are now associated with human infections, and novel Rickettsia species of undetermined pathogenicity continue to be detected in or isolated from ticks around the world. This remarkable expansion of information has been driven largely by the use of molecular techniques that have facilitated the identification of novel and previously recognized rickettsiae in ticks. New approaches, such as swabbing of eschars to obtain material to be tested by PCR, have emerged in recent years and have played a role in describing emerging tick-borne rickettsioses. Here, we present the current knowledge on tick-borne rickettsiae and rickettsioses using a geographic approach toward the epidemiology of these diseases.

Rickettsia parkeri Rickettsiosis, Argentina

Rickettsia parkeri, a recently identified cause of spotted fever rickettsiosis in the United States, has been found in Amblyomma triste ticks in several countries of South America, including Argentina, where it is believed to cause disease in humans. We describe the clinical and epidemiologic characteristics of 2 patients in Argentina with confirmed R. parkeri infection and 7 additional patients with suspected R. parkeri rickettsiosis identified at 1 hospital during 2004-2009. The frequency and character of clinical signs and symptoms among these 9 patients closely resembled those described for patients in the United States (presence of an inoculation eschar, maculopapular rash often associated with pustules or vesicles, infrequent gastrointestinal manifestations, and relatively benign clinical course). Many R. parkeri infections in South America are likely to be misdiagnosed as other infectious diseases, including Rocky Mountain spotted fever, dengue, or leptospirosis.

Identification of rickettsial infections by using cutaneous swab specimens and PCR

To determine the usefulness of noninvasive cutaneous swab specimens for detecting rickettsiae, we tested skin eschars from 6 guinea pigs and from 9 humans. Specimens from eschars in guinea pigs were positive for rickettsiae as long as lesions were present. Optimal storage temperature for specimens was 4 degrees C for 3 days.

Tick-borne rickettsioses in America: unanswered questions and emerging diseases

During most of the 20th century, Rickettsia rickettsii, the agent of Rocky Mountain spotted fever, was considered the only tick-borne rickettsia associated with human diseases in the Americas. This dogma suggested that the other characterized and noncharacterized rickettsiae isolated from ticks were not pathogenic to humans. This concept has been modified extensively in the past 10 years with the identification of at least three additional rickettsial species that cause human tick-borne rickettsioses and that are prevalent in the Americas, including Rickettsia parkeri, Rickettsia massiliae, and Rickettsia africae. Moreover, the genetic variability of R. rickettsii and the milder forms of Rocky Mountain spotted fever reactivate the hypothesis that some circulating genotypes of R. rickettsii may be more virulent than others and may explain the wide variations in fatality rates of the disease.

Epidemiology of spotted fever group and typhus group rickettsial infection in the Amazon basin of Peru

A seroprevalence study for IgG antibodies against spotted fever group (SFGR) and typhus group (TGR) Rickettsia among humans and domestic pets was conducted in the city of Iquitos, located in the Amazon basin of Peru. Of 1,195 human sera analyzed, 521 (43.6%) and 123 (10.3%) were positive for SFGR and TGR antibodies, respectively. District of residence and participant age were associated with antibody positivity for both groups, whereas rodent sightings in the home were associated with TGR antibody positivity. Of the 71 canines tested, 42 (59.2%) were positive for SFGR antibodies, and two (2.8%) were positive for TGR antibodies; one active SFGR infection was detected by polymerase chain reaction. An uncharacterized SFGR species was detected in 95.9% (71/74) of Ctenocephalides felis pools collected from domestic pets. These data suggest that rickettsial transmission is widespread in Iquitos. Rickettsia species should be further explored as potential causes of acute febrile illnesses in the region.

Closing the gaps between genotype and phenotype in Rickettsia rickettsii

Rocky Mountain spotted fever (RMSF) caused by Rickettsia rickettsii is a severe rickettsiosis that occurs in nearly every state of the continental USA. RMSF is endemic in Central and Southern America, with recent well-documented cases in Mexico, Costa Rica, Panama, Colombia, Brazil, and Argentina. RMSF is the most malignant among known rickettsioses causing severe multiorgan dysfunction and high case fatality rates, which can reach 73% in untreated cases. Variations in pathogenic biotypes of R. rickettsii isolates have been described, and potential correlations of these differences to various clinical manifestations of RMSF have been suggested. We have recently reported on a method of genetic comparison employing sequence differences in intergenic regions (IGR typing) in isolates of R. rickettsii of human, tick, and animal origin. The grouping obtained correlated well with 2 other genotyping systems we have developed, which target the presence and distribution of variable numbers of tandem repeats (TR) and insertion/deletion (INDEL) events. Twenty-five total genotypes of R. rickettsii in 4 primary groups could be distinguished: isolates from Montana, isolates associated with Rhipicephalus sanguineus ticks and human infections in Arizona, other isolates from the USA where Dermacentor variabilis is thought to be the primary vector, and the isolates primarily associated with Amblyomma ticks from Central and South America. In addition, isolate Hlp#2, which is often considered to be a nonpathogenic isolate of R. rickettsii and closely related serotype 364D, exhibited the most diversity from the other isolates compared, and they differ significantly from each other. Because complex interactions underlie the pathogenesis of R. rickettsii in vivo, it is difficult to define the causality of individual events that occur in infected vertebrate hosts and humans. Many microbial factors are likely to contribute to the varied ability of R. rickettsii to cause cellular injury; some of them may also contribute importantly to its virulence for vertebrate hosts and may be linked to the variable genetic markers we have identified. Since circulation of R. rickettsii in nature includes vertical transstadial and transovarial transmission within tick vectors and horizontal passages through vertebrate hosts, it is plausible that isolates of different virulence arose when they became isolated during adaptation to novel vertebrate and tick hosts. Characterization of the physiologically important changes in rickettsial gene expression that occur immediately after tick-to-human or tick-to-animal transitions may require development of new experimental systems.

Detection and identification of rickettsial agents in ticks from domestic mammals in eastern Panama

Several outbreaks of Rocky Mountain spotted fever have occurred in recent years in Colombian communities close to the border with Panama. However, little is known about rickettsiae and rickettsial diseases in eastern Panamanian provinces, the Darien Province and the Kuna Yala, located north of the endemic area in Colombia. In 2007, 289 ticks were collected in several towns from dogs, horses, mules, cows, and pigs. DNA was extracted from 124 Dermacentor nitens, 64 Rhipicephalus sanguineus, 43 Amblyomma ovale, 35 A. cajennense, 10 Boophilus microplus, 4 A. oblongoguttatum, and 9 A. cajennense nymphs. SYBR-Green polymerase chain reaction assays targeting a fragment of the OmpA and 16S rRNA genes were used for detection of DNA of the spotted fever group rickettsiae (SFGR) and Anaplasmataceae (Anaplasma and Ehrlichia), respectively. In total, 37.4% ticks were positive for SFGR, including 20.3% R. sanguineus, 27.9% A. ovale, 25.8% D. nitens, 50% B. microplus, 50% A. oblongoguttatum, and 100% A. cajennense. The presence of Rickettsia amblyommii DNA was confirmed by sequencing in A. cajennense, A. oblongoguttatum, A. ovale, B. microplus, and R. sanguineus. DNA of R. rickettsii was only detected in one D. nitens collected from a horse in Santa Fe, Darien Province. Prevalence of Anaplasmataceae varied from 6.3% in R. sanguineus to 26.5% in A. cajennense. DNA of Ehrlichia chaffensis was found in three D. nitens and three A. cajennense from horses. This is the first study providing molecular characterization and prevalence information on SFGR in ticks from these areas and thus will be helpful for future evaluations of the risk of rickettsial diseases for individuals living in this region.

Early diagnosis of severe Mediterranean spotted fever cases by nested-PCR detecting spotted fever Rickettsiae 17-kD common antigen gene

We describe 3 cases of Mediterranean spotted fever (MSF) who presented with severe sepsis, in 2 of which the clinical diagnosis was unclear at presentation. In each case the diagnosis of MSF was made using a nested-PCR assay for Rickettsia conorii 17-kD protein gene. The nested-PCR based diagnosis preceded the serological results of MSF that were all negative at admission. The early diagnosis of MSF by specific PCR will facilitate an early institution of appropriate therapy, saving unnecessary tests and medications.

Emerging and re-emerging tick-transmitted rickettsial and ehrlichial infections

Recently in the field of rickettsiology, an explosion of new isolates of pathogens have received species designation and new disease names, all of which have been relatively neglected by primary care and infectious disease physicians. A broad group of other tick-associated rickettsial and ehrlichial agents of unknown pathogenicity exist (eg, R amblyommii) that may cause confusion in interpreting serologic surveys or a single elevated antibody titer. Rickettsial and ehrlichial diseases are remarkable for their uniform susceptibility to doxycycline but are clinically difficult to distinguish from many viral infections and each another, and therefore misdiagnosis and failure to treat have unfortunate and sometimes tragic outcomes. Globally, many of these bacteria have been named but the genetic differences among them are often small, and many of their clinical manifestations may not be distinguishable diagnostically.