Outbreak Of Scrub Typhus Research Articles

Outbreak of scrub typhus in Puducherry & Tamil Nadu during cooler months

Background & objectives:The southern part of India has witnessed an increase in scrub typhus (ST) during the past ten years. ST outbreaks occurred during winter months but at intervals of one to three years. With only a few reports of ST in Puducherry, this study was undertaken to look for the persistence of ST cases in Puducherry and Tamil Nadu in the winter months.Methods:During relatively cooler months of September, 2012 to March, 2013, a total of 45 patients with fever and clinical suspicion of ST and who provided both acute and convalescent blood samples were included. Total WBC, platelet counts, serum creatinine, liver enzymes levels and a rapid immunochromatographic test (RICT) for ST were first done. Paired serum samples were analysed by two specific tests - ST IgM and IgG ELISA- and a non-specific, but widely used Weil-Felix (WF) test.Results:Of the 45 patients, 21 adults and seven children were confirmed as ST based on clinical and laboratory findings, and positivity in specific serological test(s). Setting ST IgM and IgG ELISA as reference, the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for RICT were 91.67, 85.71 per cent; 90.48, 100 per cent; 91.67, 100 per cent and 90.48, 80.95 per cent, respectively. Similarly, for WF the values were 83.33, 75 per cent; 95.24, 100 per cent; 95.24, 100 per cent and 83.33, 70.83 per cent, respectively.Interpretation & conclusions:ST continues to persist in the cooler months in Puducherry and neighbouring Tamil Nadu with fever and myalgia as prominent features. None of the tests evaluated in this study was found to be ideal, but ST IgM/IgG ELISA was useful for batch testing and the non-specific WF test can be used in resource poor settings.

Is scrub typhus a cause of febrile illness among paediatric population of delhi?

Sir, Scrub typhus is a febrile illness caused by Orientia tsutsugamushi and transmitted through the bite of larval forms of trombiculid mites [1]. The signs and symptoms of the disease are relatively nonspecific and in areas like Delhi where outbreaks have not been reported so far, low index of suspicion makes the diagnosis of this infection difficult. Furthermore, there is a paucity of information regarding the role of scrub typhus as a cause of fever in paediatric population. In the present study, l00 paediatric patients, 1-12years of age and presenting with febrile illness to the paediatric outpatient department or ward of a tertiary care health centre from February 2013 to March 2014 were included. Common causes of fever (malaria, dengue, enteric fever) were ruled out by history, clinical examination and appropriate laboratory investigations. In 30 patients who remained febrile and no definitive etiological diagnosis could be made, blood samples (5 ml) were collected and the serum separated and preserved at -70°C till further analysis. These samples were tested for antibodies to O. tsutsugamushi employing the immunochromatographic test (ICT), SD Bioline Tsutsugamushi Assay (Standard Diagnostics, Yongin, Korea) that employs the 56-kDa major surface protein antigens from representative O. tsutsugamushi including Gilliam, Karp, and Kato strains and detects IgG, IgM, and IgA antibodies to O. tsutsugamushi. The test was performed as per manufacturer's instructions and any positive samples further tested by an IgM ELISA (InBiOS International Inc. USA) to diagnose current infection. Among these 30 cases, ICT was positive in three (10%) samples. Further analysis of the reactive samples by IgM ELISA revealed all three samples to be IgM positive. Outbreaks of scrub typhus have been reported from various parts of India in the recent past [2,3]. Thus, there is a strong possibility of presence of this disease in this region also. All three serologically confirmed cases in the present study were residents of Delhi with no history of recent travel to a scrub typhus endemic region, a strong evidence in favour of existence of the disease in the city. The 10% prevalence of scrub typhus reported in our study is in contrast to another report from Delhi where the prevalence of scrub typhus was reported to be quiet low [4]. A study conducted in paediatric population of Sri Lanka, a region endemic for scrub typhus, has reported a prevalence of 33.33% [5]. Scrub typhus is grossly under-diagnosed due to its non-specific clinical presentation, low index of suspicion among clinicians and lack of diagnostic facilities. Since antimicrobials effective for scrub typhus are usually not included in empirical therapy for febrile illnesses, early diagnosis is imperative to reduce the mortality and complications associated with the disease. Our study highlights the existence of scrub typhus in Delhi, a region non-endemic for this infection and the need to consider it as a possible cause of paediatric febrile illnesses. To the best of our knowledge this is the first study undertaken to estimate seroprevalence of scrub typhus in paediatric population of Delhi.

A city park as a potential epidemic site of scrub typhus: a case-control study of an outbreak in Guangzhou, China.

BackgroundScrub typhus is an important public health problem in China, especially in Guangzhou city. Typical outbreaks of scrub typhus have been previously reported in rural areas, affecting mainly farmers. We describe an atypical outbreak of the disease with case fatalities, from a park in Haizhu District, Guangzhou, that could turn out to be a potential scrub typhus epidemic site.MethodsFrom May 2012 to June 2012, a case–control study was conducted to identify source and risk factors of this outbreak. Reported cases of scrub typhus in Xiaogang Park were confirmed by Weil–Felix test or a nested polymerase chain reaction (NPCR). Controls were matched with their neighbors by gender and age. Multivariate conditional logistic regression was used to identify risk factors and protective factors.ResultsA total of 29 cases were confirmed by Weil–Felix test, including 4 deaths by both Weil–Felix test and NPCR. All patients presented with fever (100%), while 28 (96.6%) cases had eschars, 10 (34.5%) headache, 10 (34.5%) chills, 6 (20.7%) lymphadenopathy, 5 (17.2%) rash, 2 (6.9%) vomiting and 1 (3.5%) presented with conjunctival congestion. The proportion of cases with activity history in Xiaogang Park was much higher than the control group (72.4% vs 24.1%, P < 0.001), and morning exercise in park or field was also as a risk factor for scrub typhus (adjusted OR = 3.0, 95% CI: 1.1 - 8.2). Four factors were significantly associated with the risk of developing scrub typhus: sitting on the lawn (adjusted OR = 8.0, 95% CI: 1.4 - 44.5), close contact with rats (adjusted OR = 3.3, 95% CI: 1.2 -9.6), sitting near the rat holes (OR = 6.8, 95% CI: 1.2 - 38.1) and wearing long-sleeved clothing when outside (adjusted OR = 0.3, 95% CI: 0.1 - 0.7).ConclusionsWe confirmed an atypical outbreak of scrub typhus in a park in Guangzhou city, which has the potential to develop into an important epidemic site. This public health risk should not be neglected and requires more attention from authorities.

Impact of Daily Average Temperature on Annual Incidence of Scrub Typhus for Predicting

Background: Scrub typhus is an acute febrile infectious disease. It is one of the most prevalent vector borne disease and occurs most frequently from October to December in Korea. The incidence of scrub typhus in Korea has shown rapidly increasing trend last decades and over 10,000 cases were reported in 2013. Weather variables are potential predictors of scrub typhus incidence. Predicting annual incidence of scrub typhus before autumn facilitates early public health responses to minimize morbidity. This study explored the impact of daily average temperature on the outbreak of scrub typhus in Korea. Methods: Analysis was performed using data on monthly weather variables and notified annual cases of scrub typhus in 68 cities, Korea from 2001 to 2008. Cities are categorized according to average annual incidence from 2001 to 2008 (High incidence area: average annual incidence &gt;30 cases/100,000 persons, medium incidence area: 10-30 cases/100,000 persons, low incidence area: 0-10 cases/100,000 persons). A Poisson generalized estimating equations (GEE) model was used to estimate the impact of daily average temperature in the summer season on annual incidence of scrub typhus. Results: For high incidence area, medium incidence area and low incidence area, the average incidence per year was increased by 31% [95% confidence interval (CI): 15, 49%], 37% [95% CI: 22, 54%] and 28% [95% CI: 11, 48%] for a 1 degrees C increase in daily average temperature in August after controlling for potential confounding effects of precipitation and humidity. Daily average temperature, precipitation and humidity of other months like June, July in summer season did not impact on annual incidence for predicting. Conclusions: These findings suggest that daily average temperature in August have a considerable impact on annual incidence of scrub typhus in Korea for predicting before coming of autumn as outbreak season.

Recent outbreak of scrub typhus in North Western part of India.

Scrub typhus usually affects previously healthy active persons and if undiagnosed or diagnosed late, may prove to be life-threatening. Diagnosis of scrub typhus should be largely based on a high index of suspicion and careful clinical, laboratory and epidemiological evaluation. To describe the diverse clinical and laboratory manifestations of scrub typhus diagnosed in Mahatma Gandhi Medical College and Hospital, Jaipur. All cases of febrile illness diagnosed as scrub typhus over a period of 3 months were analysed. Diagnosis was based on ELISA test for antibody detection against 56 kDa antigen. Forty-two cases of scrub typhus were seen over a period of 3 months (October, 2012-December, 2012). Common symptoms were high grade fever of 4-30 days duration, cough, haemoptysis and breathlessness. Eschar was not seen even in a single patient. Liver enzymes were elevated in nearly all cases (95.9%). Multiple organ dysfunction syndrome (MODS) was present in 16.66% of our patients (7 out of 42). Hypotension (6 patients, 14.2%), renal impairment (9 out of 15 patients, 60%), acute respiratory distress syndrome (4 patients, 9.52%) and meningitis (4 patients, 9.52%) were some of the important complications. There was a dramatic response to doxycycline in nearly all the patients, but initially when the disease was not diagnosed, seven patients had died. Scrub typhus has emerged as an important cause of febrile illness in Jaipur. Empirical treatment with doxycycline is justified in endemic areas.

Outbreak of scrub typhus in North India: a re-emerging epidemic

Scrub typhus is re-emerging in India. We describe an outbreak of 45 cases from our tertiary care center in north India. This outbreak included city dwellers who had no history of travel to hilly areas. The classical feature of scrub typhus, the eschar, was also noted rarely in these patients. The changing epidemiology of scrub typhus should be kept in mind while attending patients with acute febrile illness.

Scrub Typhus Outbreak, Northern Thailand, 2006–2007

During a scrub typhus outbreak investigation in Thailand, 4 isolates of O. tsutsugamushi were obtained and established in culture. Phylogenetic analysis based on the 56-kDa type-specific antigen gene demonstrated that the isolates fell into 4 genetic clusters, 3 of which had been previously reported and 1 that represents a new genotype.

Outbreak of scrub typhus in the North East Himalayan region-Sikkim: An emerging threat

Scrub typhus is an acute febrile illness that is known to be endemic in the South East Asian countries and the Western Pacific region. We here report an outbreak in the tiny Himalayan state of Sikkim. Patients with pyrexia of unknown origin were evaluated. They were screened by Weil–Felix test and the rapid immunochromatographic method. Samples that were positive by either Weil–Felix agglutination test or by rapid immunochromatography were confirmed by IgM enzyme-linked immunosorbent assay (ELISA). A total 204 samples were screened. Sixty-three patients were confirmed positive among which 42 were male and 21 were female. Effective management and early administration of antibiotics will help prevent the complications and mortality associated with scrub typhus.

Monthly Occurrence of Vectors and Reservoir Rodents of Scrub Typhus in an Endemic Area of Jeollanam-do, Korea

Monthly surveys were conducted to investigate the occurrence of chigger mites and seroprevalence of scrub typhus among small mammals in Jeollanam-do, the southwestern part of Korea, from November 2006 through October 2007. Fifty-eight small mammals, including 57 Apodemus agrarius (98.3%) and 1 Crocidura lasiura (1.7%), were captured, and a total of 4,675 chigger mites representing 4 genera and 8 species were collected from them. The chigger infestation rate among small mammals was 69.0%. The most predominant species in A. agrarius was Leptotrombidium scutellare (54.0%), followed by Leptotrombidium pallidum (39.4%), Leptotrombidium orientale (4.4%), Leptotrombidium palpale (1.1%), Neotrombicula tamiyai (0.6%), Eushoengastia koreaensis (0.3%), Neotrombicula gardellai (0.3%), and Cheladonta ikaoensis (<0.1%). The chigger index of A. agrarius was the highest in October (740.0), followed by November (242.0), September (134.6), March (98.3), February (38.2), January (35.3), December (34.5), April (30.8), and May (1.7). The average antibody positive rate of scrub typhus in wild rodents was 50.0%. The seropositive rates were high in October (100.0%) and November (83.3%), whereas those in other months were relatively low (28.6-57.1%). The chigger index of L. scutellare rapidly increased in September to form an acuminate peak in October, followed by a gradual decline. These results suggest that the outbreak of scrub typhus in the southwestern part of Korean peninsula is mostly due to L. scutellare.

Isolation and characterization of Orientia tsutsugamushi from rodents captured following a scrub typhus outbreak at a military training base, Bothong district, Chonburi province, central Thailand.

Orientia tsutsugamushi, an obligate intracellular Gram-negative bacterium, is the causative agent of scrub typhus, a vector-borne disease transmitted by infected chiggers (trombiculid mite larvae). In 2002, an outbreak of scrub typhus occurred among Royal Thai Army troops during the annual field training at a military base in Bothong district, Chonburi province, central Thailand. This report describes the outbreak investigation including its transmission cycle. Results showed that 33.9% of 174 trained troops had scrub typhus-like signs and symptoms and 9.8% of those were positive for O. tsutsugamushi-specific antibodies by indirect fluorescence antibody assay. One hundred thirty-five rodents were captured from this training area, 43% of them had antibodies against O. tsutsugamushi. Six new O. tsutsugamushi isolates were obtained from captured rodent tissues and successfully established in cell culture. Phylogenetic studies showed that these six isolates were either unique or related to a native genotype of previously described isolates from Thailand.

Emergence of Schoengastiella ligula as the vector of scrub typhus outbreak in Darjeeling: Has Leptotrombidium deliense been replaced?

Following a suspected outbreak of scrub typhus in Kurseong, Darjeeling, the Armed Forces Medical College, Pune was requested by the National Institute of Epidemiology and the State authorities to undertake investigation of the ongoing scrub typhus outbreak and suggest containment measures. The epidemic team undertook clinical, entomological and serological studies to understand the local disease pattern and delineate high risk areas, host diversity by rodent trapping using Sherman traps, mite fauna diversity, abundance and vector species identification by phase contrast microscopy for preparation of electronic database and rodent and human serological studies by Weil Felix and PCR. The results indicate no association of scrub typhus with age and sex (P=0.37 and 0.74 respectively). The maximum cases occurred amongst the tea garden workers (73%) in the age group of 25-44 years. The predominant clinical presentation was fever (100%) with headache (75%), lymphadenopathy (45%) and presence of eschar (76.7%). The dominant host species (50% of trapped rodents) was shrew Suncus murinus, the index animal for scrub typhus, which contributed maximally to the vector abundance (52.96%) with a chigger index of 61.56. The trombiculid mite Schoengastiella ligula was the vector species much against the expected mite vector Leptotrombidium deliense, in the area. The study found the presence and abundance of vector species which corroborated well with the occurrence of cases in the various localities within the subdivisions. The study thus establishes Schoengastiella ligula as the vector of scrub typhus outbreak in Kurseong, Darjeeling. Preventive and containment measures with emphasis on reduction of man - vector contact were suggested to the state authorities to contain the outbreak.

An outbreak of scrub typhus in Bishnupur district of Manipur, India, 2007

Seasonal outbreaks of febrile illness with eschar have been occurring in Bishnupur district of Manipur since 2001. The aetiology of these outbreaks was unknown. We investigated a similar outbreak in 2007 in order to confirm the aetiology and identify its risk factors. We identified 38 patients who met the case definition (attack rate: 3.4/1000), including two deaths (case fatality ratio = 5.3%). Half of the female patients had eschar on the perineal area. The clinical picture and Weil-Felix positivity suggested that the outbreak was due to scrub typhus. The disease was more common among individuals who defecated or urinated in the jungle or bushy areas from a squatting position. We recommended educating the community about the common symptoms of the disease, encouraging them to seek early treatment from public health facilities and suggested that they be taught to avoid defecating/urinating from a squatting position in the jungle.

Outbreak of scrub typhus in jammu — A report

Background: Jammu is scrub typhus prone. Scrub typhus is often seen when troops move out of permanent locations. Methods: In a prospective study cases of fever reporting to the local military hospital from July to October 2002 were examined clinically, investigated and categorised as scrub typhus when Weil Felix readings were above 1:160. Results: Twelve cases of scrub typhus were diagnosed during the period of study. The clinical features included fever, malaise and conjunctival congestion. However rashes were rare and only one had an eschar. Multisystem complications occurred in one patient. There was a spatial and temporal clustering of cases. Control of outbreak was carried out by 25% benzyl benzoate impregnation of clothing, clearing of scrub, residual spray with malathion and antirodent measures. Conclusion: Scrub typhus outbreaks have been noted whenever troops move out of permanent locations to scrub areas.

Scrub Typhus, Republic of Palau

Scrub typhus, caused by Orientia tsutsugamushi, is a severe febrile illness transmitted to humans by trombiculid mites, which normally feed on rodents. The first known outbreak of scrub typhus in Palau occurred in 2001 to 2003 among residents of the remote southwest islands. To determine the extent of scrub typhus distribution in Palau, we tested serum samples from humans and rodents for antibodies to O. tsutsugamushi. Of 212 Palau residents surveyed in 2003, 101 (47.6%) had immunoglobulin G (IgG) antibody titers >1:64, and 56 (26.4%) had concurrent IgG and IgM antibody titers >1:512 and 1:64, respectively. Of 635 banked serum samples collected from Palau residents in 1995, 34 (5.4%) had IgG antibody titers >1:64. Sera collected from rodents (Rattus norvegicus and R. rattus) in 2003 and 2005 were tested, and 18 (28.6%) of 63 had IgG antibody titers >1:64. These findings suggest that scrub typhus is endemic in Palau.

Investigation of an Outbreak of Scrub Typhus in the Himalayan Region of India

Investigation of an Outbreak of Scrub Typhus in the Himalayan Region of India

LABORATORY DIAGNOSIS OF TWO SCRUB TYPHUS OUTBREAKS AT CAMP FUJI, JAPAN IN 2000 AND 2001 BY ENZYME-LINKED IMMUNOSORBENT ASSAY, RAPID FLOW ASSAY, AND WESTERN BLOT ASSAY USING OUTER MEMBRANE 56-KD RECOMBINANT PROTEINS

Two scrub typhus outbreaks occurred among U.S. Marines training at Camp Fuji, Japan, between October 25 and November 3, 2000 and October 17 and November 30, 2001. Nine cases in approximately 800 Marines in 2000 and eight cases in approximately 900 Marines in 2001 (approximate attack rates = 1.1% and 0.9%, respectively) reported with signs and symptoms of fever, rash, headache, lymphadenopathy, myalgia, and eschar. Serologies and rapid response to doxycycline treatment indicated they had scrub typhus. Sixty-four convalescent serum samples (18 suspected cases and 46 negative controls) from U.S. Marines training at Camp Fuji during the outbreaks were assessed by enzyme-linked immunosorbent assay (ELISA), rapid flow assay (RFA), and Western blot assay for evidence of infection with Orientia tsutsugamushi, the causative agent of scrub typhus. All but one suspected case had serologic evidence of scrub typhus and all 46 control sera were non-reactive to O. tsutsugamushi antigens. The recombinant 56-kD antigen (r56) from the Karp, Kato and Gilliam strains of O. tsutsugamushi in an ELISA format provided better results than Karp r56 alone (ELISA and RFA) or whole cell antigen preparation from Karp, Kato and Gilliam (ELISA).

Outbreak of scrub typhus in southern India during the cooler months.

Orientia tsutsugamushi, the agent of scrub typhus, is a strict intracellular bacterium which is found in many parts of Asia including India. During the past few years, the number of patients with rickettsial infection and scrub typhus has increased, especially during the cooler months. We report in this study a recent outbreak of scrub typhus recorded during the cooler months (October 2001 to February 2002) in patients admitted to our hospital with acute febrile illness associated with diverse signs and symptoms. Overall, 28 patients were clinically and serologically confirmed to have scrub typhus. Fever for more than one week was the only common manifestation. Myalgias was the next most common feature (52%), and rash was observed in only 22% of the cases. Seventeen patients treated with doxycycline recovered in 1 to 3 days, as well as two patients who received chloramphenicol. In five patients who received ciprofloxacin, fever subsided only after five days. Finally three patients (10.7%) died, including one patient treated with doxycycline. These data indicate that scrub typhus is a reemerging infectious disease in India with a possibility of drug resistance. This reemergence emphasizes the need for further prospective studies to design effective control measures.

Recent studies on scrub typhus and Rickettsia tsutsugamushi in Shandong Province - China

In an outbreak of scrub typhus occurred 138 cases in 1986 in Menying County of Shandong Province of China which were confirmed through clinical and epidemiological surveys and laboratory techniques. In the endemic areas, the predominant species of mite is Leptotrombidium (L.) scutelarae and the predominant rodent is Apodemus agrarius, which may be the main vector and reservoir. Several strains of Rickettsia tsutsugamushi (R.T.) were obtained from mites, wild mice and patients, of which 3 human strains (SDH871, SDH875, SDH878) cause illness and some deaths in mice, except SDH871. The LD50 of SDH878 is 3.4. Cross-protection was observed among the strains, SDH871, SDH878, and prototype strain karp. Also the antibodies in mucoid peritoneal fluid were detectable with high titer. Shandong R.T. belongs to the serotype of the Gilliam strain.

Hemorrhagic Fever with Renal Syndrome in Korea

Several clinical variants of hemorrhagic fever with renal syndrome (HFRS) are caused by Hantaan and related viruses. Since 1951, 500-900 patients with HFRS have been hospitalized annually in Korea. Although HFRS is associated primarily with rural areas, it is now being recognized as an urban problem and a particular hazard to laboratory staff using rodents for research. Recently, epidemic outbreaks of leptospirosis and scrub typhus have occurred during the HFRS season, leading to confusion in diagnosis. Serologic diagnosis of HFRS is based on the demonstration of IgM antibodies to Hantaviruses by the indirect fluorescent antibody technique or enzyme-linked immunosorbent assay. The specific Hantavirus causing infection can be identified on the basis of titers of plaque-reduction neutralizing antibody. Results of studies with monoclonal antibodies suggest that viral subtypes exist for each Hantaviral serotype presently recognized. While infection with Hantaviruses is known to be a problem of worldwide dimensions, present evidence indicates that it occurs over a wider area than previously recognized. Vertical transmission of Hantaan virus in a pregnant woman has been documented.

Scrub typhus in eastern Taiwan, 1970.

An outbreak of scrub typhus occurred in Chinese Army personnel in the eastern part of Taiwan during 1970. This is the first outbreak of this disease documented on the main island of Taiwan since 1932. Of 21 hospitalized patients examined during the convalescent stage, 19 had antibody titers of from one to 640 to one to 10,240 as measured by indirect immunofluorescence to the Karp, Kato and Gilliam stains of Rickettsia tsutsugamushi. All were males of from 35 to 51 years and all had high fever by history. Eleven patients had eschars, six with typical black necrotic scabs. In addition, serologic evidence of prior scrub typhus infection was found in 59 of 241 other men from the two military companies involved in the outbreak. All men had been working clearing an area in hills 300 to 500 meters high. This land was originally cleared for agricultural use, but had been abandoned over 4 years previously. Rickettsia tsutsugamushi was recovered from rodents and chiggers (Leptotromibidium deliense) captured in the area.