OUTBREAK OF SCRUB TYPHUS IN PYREXIA OF UNKNOWN ORIGIN DURING COOLER MONTHS IN GUNTUR DISTRICT, ANDHRA PRADESH, SOUTH INDIA

Dr. Y. Umarani, * Dr. D. Sarada, Dr. Jyothi P, Dr. E. Vandana, Dr. R. Suma Kalyani and Dr. M. Rajarajeswari. Assistant Professor, Department of Microbiology, Siddhartha Medical College, Vijayawada, Andhra Pradesh. ...................................................................................................................... Manuscript Info Abstract ......................... ........................................................................ Manuscript History


ISSN: 2320-5407
Int. J. Adv. Res. 5 (9), 615-621 616 PUO can be defined as temperature above 38.3 o C for more than one week duration and there are multiple causes like Malaria, Dengue, Flu, Enteric fever and Tuberculosis. Scrub typhus is a very less known cause of PUO always under diagnosed in India due to its non specific clinical presentations, low level of suspicion amongst clinicians, lack of awareness and limited diagnostic facilities. The disease is endemic in East Asia from Korea to Indonesia and in Pacific Islands including Australia and was first observed in Japan.
An outbreak of PUO was observed in Guntur district, Andhra Pradesh during cooler months from September 2013 to February 2014. A total of 216 cases were recorded in medical OP at GGH, Guntur. Only suspected cases of PUO with presence of characterstic eschar were tested for IgM antibodies by Weil-Felix and rapid ICT test. The positive tests were further confirmed by IgM ELISA. The present study was undertaken to estimate the prevalence of the disease in clinically suspected patients to compare rapid ICT which is simple and IgM ELISA method. There was 96.5% and 98.3% positivity in rapid ICT and ELISA respectively than Weil-Felix test which is neither sensitive nor specific for diagnosis of these diseases.

Materials And Methods:-
A total of 216 patients attended the medical OP in GGH Guntur with PUO from September 2013 to February 2014 and a number of 58 suspected cases were screened for scrub typhus by Weil-Felix agglutination test containing Proteus vulgaris antigen suspension OX19, OX2 and Proteus mirabilis antigen suspension OXK(Tulip diagnostic Pvt Ltd Goa, India) and Rapid Immunochromatographic assay or ICT (standard diagnostics, Bioline, Inc, Korea) containing a major surface protein 56KDa antigen representative of Orientia tsutsugamushi (Karp, Kato, Gilliam). Weil-Felix test with a titre of >1:160 and ICT positive were considered positive. All 58 positive for IgM antibodies of scrub typhus were further confirmed by IgM ELISA (Bio International seatle, WA, USA) that used recombinant antigens to detect IgM antibodies for O tsutsugamushi.
The data was statistically analysed on SPSS 17.0 software by using chi-square (x2) test. The probability value (P value) was calculated and P-value of less than 0.00001 was considered significant.

Results:-
A total of 216 patients with PUO reported to Medical OP, GGH, Guntur from September 2013 to February 2014. Among 216, only suspected cases with fever >38.3 0 C for more than one week with eschar were screened for IgM antibodies for Scrub typhus and 58 cases were Seropositive. More number of cases were reported in the months of September and October in 2013(Figure1).
Among these 58 positive cases 36(62.9%) were male and 22(37.9%) were female. Males were more affected than females. Age-wise and sex-wise distribution and their seropositivity are shown in figure2. Age group of the patients ranged between 2 to 80 years. The seropositivity for IgM antibodies was highest in 41-60 yrs (56.8%) age group followed by 21-40yrs (32.7%) in both sexes.
The laboratory parameters thrombocytopenia, deranged liver function tests and renal function tests were seen in 48(82.7%), 42(72.4%) and 14(24.1%). Total Leucocyte count was raised in 44(75.8%) ( Table III). Most of the patients were from rural areas belonging to Guntur, Prakasam and Krishna districts of Andhra Pradesh. Number of cases reported during cooler months between September and October were high. All 58 cases were negative for common causes of fever such as typhoid, tuberculosis, malaria, dengue, HIV and Hepatitis B. All cases diagnosed as scrub typhus were followed up and one death was reported and it was not significant.

Discussion:-
Rickettsial infections are reemerging with increasing reports from India and other countries with considerable morbidity and mortality. Scrub typhus is a rickettsial infection caused by Orientia tsutsugamushi. Incidence of scrub typhus varies from 0.8% to 60% in different countries.
Among 216 recorded cases with PUO, a total of 58 cases reported with fever >38.3 o C with chills and rigors, were tested for the presence of antibodies and were found to be positive. Among these 36 were males and 22 were females. Incidence was more among males than females and this correlates with studies by S Gurung et al. In this study, one death 1.7% has been reported due to acute respiratory failure with fever, cough and dyspnoea. R. Bithu et al. reported a mortality of 9.7% in their study of 133 cases with common cause of death as acute respiratory failure presenting with fever, cough and dyspnoea.
The diagnosis of scrub typhus is a problem due to low index of suspicion and lack of diagnostic facilities in India. Weil-Felix test is widely used in diagnosis of rickettsial diseases but this test is neither sensitive nor specific. The test result may be negative during early stages of disease, the antibodies are detectable only during second week of the onset of the disease. It has been replaced by more accurate and sensitive immunological tests. Among these, specific immunological tests, indirect immunofluorescence test and PCR which provide accurate and specific diagnosis, either not available or are too expensive. There is need for a rapid technically simple and economic test. ELISA is an easy and comparatively economic test. In the present study suspected cases (58) were screened with W-F test and rapid immunochromatographic assay and positive cases were further confirmed by IgM ELISA. Gurung et al., reported positive test with W-F 51, ICT in 64 and IgM ELISA in 63 patients. In our study 2 samples were negative by rapid method but positive by ELISA and one sample positive by rapid method (ICT) was negative for ELISA which correlated with the study of Gurung et al., with one patient's sample positive for Weil-Felix and ICT and negative for IgM ELISA. By using rapid test and ELISA for detection of antibodies of scrub typhus the positivity was 96.5% and 98.2% in our study. The difference was statistically significant. Sharma et al. tested 150 samples from patients with PUO of which 52 were found to be positive for OXK antibodies by Weil-Felix test. Therefore it can be concluded that both rapid test and ELISA are equally good. In the high work load centres, ELISA should be used but with less number of samples rapid method may be used for early diagnosis of scrub typhus.  Conclusion:-Scrub typhus is prevalent but an under diagnosed disease in India. Scrub typhus cases have been reported from neighbouring states like Tamil Nadu, Pondicherry, Kerala, Karnataka and Orissa. The climatic conditions in Andhra Pradesh are more or less similar to these states. Therefore it is recommended that scrub typhus should be included in the differential diagnosis of Pyrexia of Unknown Origin along with other endemic diseases during cooler months between September and October in this region. Rapid ICT and specific diagnostic methods using ELISA can be carried out timely for early diagnosis of scrub typhus. An early empiric therapy with Doxycycline and Azithromycin can be given to reduce serious complications which are associated with high mortality.