Simple method to differentiate among Rickettsia species.

In this work we present a new option to identify 11 rickettsial species that cause human rickettsioses, with some advantages over the previous methods described. Using rickettsial isolates from 11 Rickettsia species as a sample, we used the polymerase chain reaction to amplify a 990- to 1,000-bp DNA fragment from the ompB gene, common for the 11 Rickettsia species analyzed in this study, which were digested with AluI restriction enzyme to obtain different digestion patterns. This restriction pattern can be visualized using a polyacrylamide gel electrophoresis technique. Using this method we could differentiate between the 11 Rickettsia species analyzed regardless of the group to which the Rickettsia belonged. We developed a simple method to identify 11 Rickettsia species which cause human rickettsioses using polymerase chain reaction and restriction fragment length polymorphism techniques with the advantage that it only needs one amplicon and only one restriction enzyme to obtain the restriction pattern. The identification of the species infecting vectors, reservoirs, and humans is essential to establish the ecological and behavioral ecosystem involved in its maintenance and transmission in nature in the specific region where the pathogen is circulating. This method is very helpful to identify Rickettsia species in a short time.

Toxoplasma gondii presence in women with spontaneous abortion in Yucatan, Mexico.

The objective of this study was to estimate the seroprevalence of anti- Toxoplasma gondii antibodies and DNA of women with spontaneous abortions in 2 hospitals located in Yucatan, Mexico. Between June 2008 and May 2009, blood samples were taken from 100 women with spontaneous abortion attending the Ticul City Communitarian Hospital and the Merida Mother-Kid Hospital. The sera were tested for anti- T. gondii IgG and IgM antibodies. Blood samples (5 ml with anticlotting agent) were also used for polymerase chain reaction (PCR) assay, to detect T. gondii DNA. Forty-two of the 100 samples were negative. Of the positive samples (n = 58), 32 were positive to IgG, 2 to IgM, 5 to IgG and IgM, 6 to IgG and PCR, 1 to IgM and PCR, and 12 to IgG, IgM, and PCR. Accordingly, 55% of the women were seropositive to at least IgG, 20% to at least IgM, and 19% via PCR. Differences between hospitals were significant (P < 0.05) only for IgM. The risk of infection (IgM positive) was 2.85 (odds ratio [OR] 95%, confidence interval [CI]; 1.03-7.87) times greater in women patients at the Merida Mother-Kid Hospital, than those at the Ticul Communitarian Hospital. More studies are needed to evaluate the impact of this disease and to establish strategies to follow in order to reduce congenital toxoplasmosis in the populations at risk.

Murine Typhus: Clinical and epidemiological aspects.

RICKETTSIA TYPHI: is an intracellular bacteria who causes murine typhus. His importance is reflected in the high frequency founding specific antibodies against Rickettsia typhi in several worldwide seroepidemiological studies, the seroprevalence ranging between 3-36%. Natural reservoirs of R. typhi are rats (some species belonging the Rattus Genus) and fleas (Xenopsylla cheopis) are his vector. This infection is associated with overcrowding, pollution and poor hygiene. Typically presents fever, headache, rash on trunk and extremities, in some cases may occur organ-specific complications, affecting liver, kidney, lung or brain. Initially the disease is very similar to other diseases, is very common to confuse the murine typhus with Dengue fever, therefore, ignorance of the disease is a factor related to complications or non-specific treatments for the resolution of this infection. This paper presents the most relevant information to consider about the rickettsiosis caused by Rickettsia typhi.

RICKETTSIA TYPHI: es una bacteria intracelular causante del tifo murino. Su importancia queda reflejada en la elevada frecuencia con que se encuentran anticuerpos específicos frente a Rickettsia typhi en diferentes estudios seroepidemiológicos a nivel mundial, variando la seroprevalencia entre el 3-36%. R. typhi tiene como reservorios naturales a las ratas (especies del Género Rattus) y como vector las pulgas (Xenopsylla cheopis). Esta infección está asociada comúnmente al hacinamiento, contaminación y falta de higiene. Clínicamente se presenta fiebres, cefalea, exantema en tronco y extremidades, en algunos casos pueden presentarse complicaciones órgano-específicas, afectando hígado, riñón, pulmón o cerebro. Inicialmente la enfermedad es muy similar a otras enfermedades, siendo muy común confundir al tifo murino con fiebre causada por Dengue, por lo tanto, el desconocimiento de la enfermedad es un factor relacionado a complicaciones ó tratamientos poco específicos para la resolución de esta infección. Este trabajo presenta la información más relevante a considerar sobre la Rickettsiosis causada por Rickettsia typhi.

Human rickettsialpox, southeastern Mexico.

The detection of Rickettsia akari in 2 human patients increased the diversity of rickettsioses affecting the public health in the southeast of Mexico. Rickettsialpox should be considered in the differential diagnosis with other febrile illnesses for the correct diagnosis and accurate treatment of this potential threat to human health.

Severe human infection with Rickettsia felis associated with hepatitis in Yucatan, Mexico.

Rickettsia felis infection usually is a mild-to-moderate illness characterized by general signs and symptoms. Generally, patients do not require hospitalization. However, we detected 2 severe infections with R. felis. Our findings support the importance of R. felis infection as a potentially severe illness in humans.

Murine typhus in child, Yucatan, Mexico.

A case of murine typhus in Yucatan was diagnosed in a child with nonspecific signs and symptoms. The finding of Rickettsia typhi increases the number of Rickettsia species identified in Yucatan and shows that studies are needed to determine the prevalence and incidence of rickettsioses in Mexico.

A dog naturally infected with Rickettsia akari in Yucatan, México.

Rickettsia akari is the causative agent of rickettsialpox, a primarily urban mite-borne rickettsiosis that is encountered in the United States and in a few countries around the world. Its vector is the mite Liponyssoides sanguineus, which is found on rats and mice, which serve as reservoirs for the disease. In this work we report a severe animal case of R. akari infection with two unusual features: R. akari was found in a dog, and its potential vector was a tick.

Short report: Rickettsia felis outer membrane protein A: a potential tool for diagnosis of patients with flea-borne spotted fever.

Rickettsia felis infection in humans has been detected worldwide, causing an illness that could be confused with other viral and bacterial infections such as dengue fever. Despite the high incidence of infection in humans, reservoirs, and vectors, the definitive diagnosis of R. felis infection currently requires polymerase chain reaction and sequencing because its antigens are closely related to other rickettsiae, making serologic diagnosis problematic. In this work, we report the immune reactivity of sera from four patients infected with R. felis with recombinant peptides representing regions of outer membrane protein A of R. felis.

An increase in human cases of spotted fever rickettsiosis in Yucatan, Mexico, involving children.

The first human case of infection caused by Rickettsia in Yucatan was detected in 1996, and it was determined that the species was R. felis. Since then, passive epidemiologic surveillance was implemented to search for human cases in the public hospitals of the state, and in 2005, the first human case of Rocky Mountain spotted fever was detected. During the following 2 years, eight new confirmed cases and one probable case were identified. Seven cases involved children younger than 12 years of age, with a fatal outcome in three of the cases. Children are a particularly vulnerable population for this serious emerging infection.

Hemorrhagic pulmonary leptospirosis: three cases from the Yucatan peninsula, Mexico.

Three leptospirosis cases with lung involvement are reported from the Yucatan Peninsula, Mexico. All three patients were admitted to the intensive care unit due to acute respiratory failure. Treatment with antibiotics resulted in favorable evolution despite the negative prognosis. Leptospirosis should be included in the differential diagnosis of patients with fever and lung involvement.

Hemorrhagic pulmonary leptospirosis: three cases from the Yucatan peninsula, Mexico / Leptospirose hemorrágica pulmonar: três casos na península de Yucatán, México

Three leptospirosis cases with lung involvement are reported from the Yucatan Peninsula, Mexico. All three patients were admitted to the intensive care unit due to acute respiratory failure. Treatment with antibiotics resulted in favorable evolution despite the negative prognosis. Leptospirosis should be included in the differential diagnosis of patients with fever and lung involvement.

Analisamos três casos de leptospirose com envolvimento pulmonar na Península Yucatán, México. Os três pacientes com seqüelas pulmonares entraram na unidade de cuidados intensivos devido à insuficiência respiratória grave. Todos os casos evoluíram favoravelmente ao tratamento com antibióticos, apesar do prognóstico negativo. Leptospirose deve ser incluída no diagnóstico diferencial de pacientes com febre e comprometimento pulmonar.

Rickettsia felis as emergent global threat for humans.

Rickettsia felis is an emergent pathogen belonging to transitional group rickettsiae. First described in 1990, R. felis infections have been reported to occur worldwide in fleas, mammals, and humans. Because clinical signs of the illness are similar to those of murine typhus and other febrile illnesses such as dengue, the infection in humans is likely underestimated. R. felis has been found throughout the world in several types of ectoparasites; cat fleas appear to be the most common vectors. R. felis infection should be considered an emergent threat to human health.

Fatal human infection with Rickettsia rickettsii, Yucatán, Mexico.

The first fatal Rickettsia rickettsii infection was diagnosed in the southwest of Mexico. The patient had fever, erythematous rash, abdominal pain, and severe central nervous system involvement with convulsive crisis. The diagnosis of R. rickettsii infection was established by immunohistochemistry and specific polymerase chain reaction.

Rickettsia felis, the agent of an emerging infectious disease: Report of a new case in Mexico.

The fourth case of human infection with Rickettsia felis in Yucatán, Mexico was documented by serologic testing and polymerase chain reaction (PCR). The role of R. felis in human disease has been demonstrated by molecular methods in a few patients from the U.S., Yucatán, Brazil and Germany. Apparently, there is a wide spectrum in the clinical presentation of the worldwide reported cases.

Transcription of the Rickettsia felis ompA gene in naturally infected fleas.

Rickettsia felis is maintained transovarially in Ctenocephalides felis fleas in a widespread geographic distribution and is transmitted to humans and animals, including opossums. This rickettsia is phylogenetically a member of the spotted fever group, most closely related to Rickettsia akari and R. australis. An unusual feature of this rickettsia is that the gene for the outer membrane protein A (OmpA) is interrupted by stop codons. To determine if this putatively dying gene is expressed, mRNA was extracted from laboratory-maintained, R. felis-infected cat fleas. Reverse transcriptase-polymerase chain reaction amplification of three segments of the ompA gene indicated that mRNA of ompA is actively transcribed in fleas. The cDNA sequences expressed represented mRNA of the first 1860-basepair segment of ompA, which includes domains I and II, part of domain III, the region from site 1836 to site 2180, despite the presence of several stop codons, and the open reading frame from site 2788 to site 3837. The detected sequences showed several differences in the amino acid composition when compared with the previously reported sequence.

Clinical and laboratorial evidence of Rickettsia felis infections in Latin America.

After the discovery and initial characterization of Rickettsia felis in 1992 by Azad and cols, and the subsequent first description of a human case of infection in 1994, there have been two communications of human rickettsiosis cases caused by Rickettsia felis in Latin America. The first one was published in 2000 by Zavala-Velazquez and cols in Mexico. In 2001 Raoult and cols described the occurrence of two human cases of Rickettsia felis rickettsiosis in Brazil. In the present discussion these two articles were compared and after the description of the principal signs and symptoms, it was concluded that more studies are needed with descriptions of a greater number of patients to establish the true frequency of the clinical signs and symptoms present in Rickettsia felis rickettsiosis.

Clinical and laboratorial evidence of Rickettsia felis infections in Latin America

Depois da descoberta e caracterização inicial da Rickettsia felis em 1992 por Azad e cols, e à descrição subseqüente do primeiro caso de infecção humana em 1994, houveram duas comunicações de rickettsioses causadas por Rickettsia felis na América Latina. A primeira foi feita por Zavala-Velazquez e cols em 2000 no México. Em 2001, Raoult e cols descreveram a ocorrência de dois casos humanos de rickettsiose por Rickettsia felis no Brasil. Na presente discussão, esses dois artigos foram comparados, e depois da descrição dos principais sinais e sintomas, conclui-se que outros estudos são necessários, com a participação de um maior número de pacientes, para se estabelecer a verdadeira freqüência dos sinais clínicos e sintomas presentes nas rickettsioses por Rickettsia felis.

Clinical-epidemiological study of leptospirosis in humans and reservoirs in Yucatan, Mexico

A leptospirosis clinical-epidemiological study was made in humans and reservoirs in the state of Yucatßn, MÚxico. Interviews and serological analyses were made on 400 persons from an open population, 439 probable cases of leptospirosis and 1060 animal reservoirs (cows, pigs, dogs, rats and opossums). IgM Leptospira DipstickTM and Microscopic Agglutination Test (MAT) was used to detect human antibodies to leptospiras and serovar respectively. Leptospirosis incidence in humans was 2.2/100,000 inhab. in 1998, 0.7/100,000 in 1999 and 0.9/100,000 in 2000. Overall seroprevalence was 14.2 percent, relatively unchanged from seroprevalences observed 20 years ago. Highest seropositivity was found in people over 56 years of age, predominating males over females. Predominant serovars in the open population were tarassovi, hardjo, pomona and panama. Leptospirosis cases were most frequent in rural areas, and the anicteric course predominated over the icteric. The panama, icterohaemorrhagiae and pomona serovars predominated in both anicteric and icteric courses. Dogs, pigs and rodents had the highest seropositivity among the reservoirs. Contact with rodents and natural water sources were significant factors (p ú 0.05). Human cases (74 percent) occurred during the rainy season. It is concluded that leptospirosis is still a serious illness with important clinical and epidemiological implications in the state of Yucatßn, Mexico