Hospital-Based Surveillance for Infectious Etiologies Among Patients with Acute Febrile Illness in Georgia, 2008-2011.

Information on the infectious causes of undifferentiated acute febrile illness (AFI) in Georgia is essential for effective treatment and prevention. In May 2008, a hospital-based AFI surveillance was initiated at six hospitals in Georgia. Patients aged ≥ 4 years with fever ≥ 38°C for ≥ 48 hours were eligible for surveillance. Blood culture and serologic testing were conducted for Leptospira spp., Brucella spp., West Nile virus (WNV), Crimean-Congo hemorrhagic fever virus, Coxiella burnetii, tick-borne encephalitis virus (TBEV), hantavirus, Salmonella enterica serovar Typhi (S. Typhi), and Rickettsia typhi. Of 537 subjects enrolled, 70% were outpatients, 54% were males, and the mean age was 37 years. Patients reported having fatigue (89%), rigors (87%), sweating (83%), pain in joints (49%), and sleep disturbances (42%). Thirty-nine (7%) patients were seropositive for R. typhi, 37 (7%) for Brucella spp., 36 (7%) for TBEV, 12 (2%) for Leptospira spp., 10 (2%) for C. burnetii, and three (0.6%) for S. Typhi. None of the febrile patients tested positive for WNV antibodies. Of the patients, 73% were negative for all pathogens. Our results indicate that most of the targeted pathogens are present in Georgia, and highlight the importance of enhancing laboratory capacity for these infectious diseases.

Challenges of establishing the correct diagnosis of outbreaks of acute febrile illnesses in Africa: the case of a likely Brucella outbreak among nomadic pastoralists, northeast Kenya, March-July 2005.

An outbreak of acute febrile illness was reported among Somali pastoralists in remote, arid Northeast Kenya, where drinking raw milk is common. Blood specimens from 12 patients, collected mostly in the late convalescent phase, were tested for viral, bacterial, and parasitic pathogens. All were negative for viral and typhoid serology. Nine patients had Brucella antibodies present by at least one of the tests, four of whom had evidence suggestive of acute infection by the reference serologic microscopic agglutination test. Three patients were positive for leptospiral antibody by immunoglobulin M enzyme-linked immunosorbent assay, and two were positive for malaria. Although sensitive and specific point-of-care testing methods will improve diagnosis of acute febrile illness in developing countries, challenges of interpretation still remain when the outbreaks are remote, specimens collected too late, and positive results for multiple diseases are obtained. Better diagnostics and tools that can decipher overlapping signs and symptoms in such settings are needed.

Comparison of four commercial IgM and IgG ELISA kits for diagnosing brucellosis.

Brucellosis is a worldwide zoonotic disease that often requires serology for diagnosis. The serum agglutination test is the gold standard assay, but ELISAs are used by many laboratories. Many commercial ELISAs are available, but few studies have compared their performance. This study compared the ability of four commercially available ELISA kits (from Bio-Quant, Immuno-Biological Laboratories - America, Vircell and Euroimmun) to diagnose brucellosis in patients from Egypt and the USA. The sensitivities for all kits tested, except the Vircell kit, were >90%, whilst the specificities were variable, with the Bio-Quant assay having a specificity of <40%. Detection of IgG antibody was more sensitive than detection of IgM antibody for diagnosing brucellosis cases, but the specificity was comparable. Overall, there was good agreement between all of the kits except for the Bio-Quant kit. None of the diagnostic assays was 100% reliable for diagnosing brucellosis; therefore, serology results need to be considered in tandem with patient history, clinical signs and other test results.

Evaluation of a newly developed ELISA against Widal, TUBEX-TF and Typhidot for typhoid fever surveillance.

INTRODUCTION: Typhoid fever is endemic in many parts of the world and represents a major cause of acute febrile illness (AFI). Rapid and accurate laboratory methods for diagnosis of this disease are needed for both patient care and surveillance situations. METHODOLOGY: Serum samples were collected from AFI patients and used to evaluate the performance of a newly developed ELISA assay that uses a mixture of somatic and flagellar antigens to detect the total antibody response against Salmonella enterica subspecies enterica serovar Typhi (S. Typhi) infection. The levels of Ig isotype response (IgG, IgM and IgA) were also evaluated, and results were compared to those of TUBEX-TF and Typhidot commercial kits.  RESULTS: Of 234 culture-confirmed typhoid patients, the total Ig ELISA diagnosed 93% compared to 71% using Widal test. This sensitivity level (93%) is higher than that observed for the individual Ig ELISAs (IgG 75%; IgM 79%; IgA 57%) and the commercial tests TUBEX-TF (75%), Typhidot IgM (63%) and Typhidot IgG (28%). An agreement of 78% was achieved between the total Ig ELISA and Widal test. The average specificity of the ELISA was 96%. Using ELISA, up to 200 samples can be tested per run with cost per test at US$0.20. CONCLUSIONS: The developed ELISA shows superior sensitivity and specificity, when compared to Widal, TUBEX-TF and Typhidot assays, is more cost effective and allows higher throughput. This method is highly recommended for active surveillance studies or outbreak investigations of typhoid fever.

Concurrent infections in acute febrile illness patients in Egypt.

We report the occurrence of concurrent infections with multiple acute febrile illness (AFI) pathogens during an ongoing prospective laboratory-based surveillance in four infectious disease hospitals in urban and rural areas of Egypt from June 2005 to August 2006. Patients were screened for Leptospira, Rickettsia typhi, Brucella, or Salmonella enterica serogroup Typhi by various methods including serology, culture, and PCR. One hundred eighty-seven of 1,510 patients (12.4%) evaluated had supporting evidence for the presence of co-infections; 20 (1%) of these patients had 2 or more pathogens based upon confirmatory 4-fold rise in antibody titer, culture, and/or PCR. Most coinfected patients lived or worked in rural agricultural areas. The high coinfection rates suggest that defining the etiologies of AFI is imperative in guiding proper disease treatment, prevention, and control strategies in Egypt.

Rapid diagnosis of typhoid fever by enzyme-linked immunosorbent assay detection of Salmonella serotype typhi antigens in urine.

We developed and evaluated an enzyme-linked immunosorbent assay (ELISA) using monoclonal antibodies to capture somatic antigen 9 (O9), flagellar antigen d (Hd), and the Vi capsular polysaccharide antigen (Vi) from the urine of persons with and without typhoid fever. Sequential urine samples were collected from 44 patients with blood culture-confirmed typhoid fever and from two control groups. The first control group included patients with brucellosis (n = 12) and those with clinically diagnosed, non-typhoid, acute, febrile illness (n = 27). The second control group was a sample of healthy volunteer laboratory workers (n = 11). When assessed relative to date of fever onset, sensitivity was highest during the first week for all three antigens: Vi was detected in the urine of nine (100%) patients, O9 in 4 (44%) patients, and Hd in 4 (44%) patients. Sequential testing of two urine samples from the same patient improved test sensitivity. Combined testing for Vi with O9 and Hd produced a trend towards increased sensitivity without compromising specificity. The specificity for Vi exceeded 90% when assessed among both febrile and healthy control subjects, but was only 25% when assessed among patients with brucellosis. Detection of urinary Vi antigen with this ELISA shows promise for the diagnosis of typhoid fever, particularly when used within the first week after fever onset. However, positive reactions for Vi antigen in patients with brucellosis must be understood before urinary Vi antigen detection can be developed further as a useful rapid diagnostic test.