Prolonged fever is defined as fever more than 2 weeks duration greater than 38.3
◦ C (101 ◦ F) on several occasions. The causes of prolonged fever are classified in to 4 major groups:
• infections (most common cause).
• non-infectious inflammatory diseases (NIID).
• malignancies.
• miscellaneous conditions.

Infection is the most common diagnosis in most cases of prolonged fever especially in developing countries which include:
•Bacterial (salmonellosis , tuberculosis
,brucellosis, and abdominal or pelvic abscesses
,osteomyelitis, infective endocarditis,
Pyelonephritis and tuberculous meningitis ).
•Viral (CMV, EBV, Herpes viruses , and HIV).
•Rickettsial ( Q fever) .
•Parasitic infections.

•
The common infections in Egypt causing prolonged fever that we will study in this
essay as regard the diagnosis especially the serology are:
•salmonellosis ,
•tuberculosis(TB) ,
•brucellosis,
•Q fever,
•Epstein-Barr virus (EBV),
•chronic meningitis.

-Typhoid fever (enteric fever) is caused by the
Gram-negative bacterium Salmonella enterica serotype typhi.
-Estimates for the year 2000 suggest there are approximately 21.5 million infections and 200,000 deaths from typhoid fever globally each year .
-The clinical manifestations of typhoid fever are usually nonspecific , and include prolonged fever and gastrointestinal symptoms.

-In Bilbeis district (population 664,000) in Lower
Egypt the estimated incidence of typhoid fever was calculated to be 13 cases per 100,000 persons per year .
-Also the results of population-based surveillance in Fayoum governate indicate that incidence of typhoid fever was 59 cases per 100,000 persons per year.

-The causative agent is Brucella spp., ( Gramnegative intracellular coccobacillus discovered by
David Bruce in 1887).
-Brucellosis is a relatively common condition and may present with prolonged fever without a focus, however due its wide spectrum of clinical symptoms it remains an important diagnostic challenge.
-It is a zoonotic disease found worldwide, with a high morbidity rate.

-Brucellosis is endemic in the middle East.
-In Egypt 11% of the population had serological evidence of infection with Brucella spp., while in acute febrile illnesses 3% of all bacteraemias were caused by the organism .
-Although brucellosis is recognized as a common cause of fever in various parts of Egypt, it is often misdiagnosed and mistreated.
-More than half of all brucellosis cases were misdiagnosed as typhoid, and only a quarter of them received treatment with more than one antibiotic.

-Tuberculosis is caused by Mycobacterium tuberculosis complex (MTBC).
-Tuberculosis may involve every organ in the body but the most common clinical presentation is pulmonary disease.
-In 2006, 9.2 million new active disease cases (4.1
million being sputum smear-positive) corresponding to an estimated incidence of 139 per 100,000 population occurred throughout the world.
-The highest incidence rate was recorded for the
African region , mainly due to high prevalence of HIV infection.

revealed that the incidence of smear-positive cases in Egypt is 16 per 100,000 population,
This report concluded that TB and especially drug-resistant strains of Mycobacterium tuberculosis pose serious public health problems and that multiple drug resistance and low cure rates are the most important problems facing TB control efforts in Egypt .

Q fever is a widespread zoonotic disease, caused by Coxiella burnetii (C. burnetii). Wild and domestic animals are the reservoir of C. burnetii, It is a zoonosis occurring worldwide.
Q fever is associated with a wide spectrum of clinical manifestations. In most cases, this illness has a selflimiting febrile course, but it may also manifest with a variety of non-specific symptoms. As with most other rickettsioses, Q fever is infrequently suspected and remain unrecognized .

*The clinical triad of pharyngitis , fever , and lymphadenopathy was first described as “ glandular fever, ” .
*IM is caused by the Epstein Barr virus (EBV), which infects more than 98% of the world ’ s adult population .
*The overall clinical incidence is 45/100 000 and it is particularly common in adolescence.
*IM is a clinical syndrome characterized by fever, fatigue, malaise, lymphadenopathy and sore throat.

-Chronic meningitis is defined by persistent or clinically progressive signs and symptoms of meningitis, such as headache, fever, stiff neck, nausea, vomiting, lethargy, and confusion associated with cerebrospinal fluid (CSF) changes lasting for a duration of at least 4 weeks without improvement.

-Chronic meningitis is caused by a wide variety of infectious and noninfectious pathogens that remain difficult to diagnose.
In Egypt, Tuberculous meningitis (TBM) being one of the most common causes of bacterial meningitis and being associated with a high mortality
(47%) and it continues to be a significant public health problem .

Although the mainstay of diagnosing typhoid fever is a positive blood culture it is time-consuming and takes at least 2 to 5 days until the identification of the organism.
PCR is a better alternative because it is sensitive and rapid method. PCR-based diagnoses are superior to the classical serological method, Widal test, and blood culture test in terms of their specificity and sensitivity .
Nested PCR had higher efficacy in detecting typhoid fever than Widal test, blood and urine cultures .

Isolation of brucella from blood, bone
marrow, lymph nodes or cerebrospinal fluids remains the gold-standard for diagnosis of brucellosis in humans.
Despite its high specificity, brucella culture has several drawbacks such as slow growth and poor sensitivity.
PCR proved to be a very useful tool not only for the diagnosis of acute brucellosis but also as a predictive marker for the course of the disease and the post treatment follow-up, which is valuable for the early detection of
relapses .

Tuberculosis (TB) diagnosis
Microscopy is still the backbone of
laboratory diagnostics in TB. Many nucleic acid amplification methods are much more sensitive than sputum microscopy, and results can be available within several hours.
The cost and complexity of existing nucleic acid amplification methods has limited their application in resource-poor settings.
Transrenal DNA provides a challenging new target for molecular tuberculosis diagnosis in all groups of patients.

The isolation of the Q fever pathogen is a reliable diagnostic method, but it remains timeconsuming and hazardous and requires biosafety.
The PCR assays performed are better tests than pathogen isolation for the rapid and reliable diagnosis of Q fever.

Quantitative Epstein bar virus (EBV) DNA measurement is essential for differentiating the low-level infection of healthy carriers from the high levels characteristic of EBV-related disease. Realtime PCR is the principal technology used for modern EBV viral load measurement.

The identification of meningitis etiology is primarily based on the examination of CSF and other tissues, which includes direct stain , cultures on aerobic, anaerobic media . However, even with the use of modern techniques, the etiology of chronic meningitis remains unknown in a substantial percentage of patients. The CSF polymerase chain reaction
(PCR) assay represents a significant advance in the diagnosis of TBM. The results of PCR studies in the CSF have shown a
94 — 100% specificity but sensitivities ranging from 75% to
100%.
CT and MRI are used in the evaluation of TBM and to identify complications.

The most widely used serologic test is the Widal test, However, false-positive results are common because of antigenic cross sharing with other salmonella serotypes . Several new serologic tests for typhoid fever have been introduced which detect
IgM or IgG antibodies to various purified antigens of
S. Typhi. The assay methods used include enzymelinked immunosorbent assay (ELISA), dot-blot ELISA, immunochromatography and a novel particle separation method used in TUBEX. The TUBEX test is simple and rapid to use not only in hospitals but also for outpatients as well. It is good alternative for widal test .

Typhidot-M is a dot enzyme immunoassay for the detection of specific IgM to Salmonella typhi .
Typhidot-M was positive in 97% of cases who presented with fever of <7 days among blood culture positives as compared to Widal, which was positive in 24.2%.
It is a dot-Enzyme Immunoassay (EIA), a new serologic test based upon the presence of specific IgM antibodies to a specific 50 kDa outer membrane protein (OMP) antigen on
Salmonella typhi. The test become positive as early as in the first week of the fever, the results can interpreted visually and available within one hour

Serological testing often is used for the confirmation of brucellosis. The agglutination tests in tubes, e.g serum agglutination test (SAT), or on slides (Rose Bengal) continue to be the mainstay of laboratory diagnosis . . However, SAT and the other formats of direct agglutination tests suffer from high false negative rates in complicated and chronic cases
ELISA is one method that has been incorporated into serologic diagnosis of brucellosis. Among its advantages are speed and automatization. ELISA also allows detection of antibodies against different bacterial antigenic structures such as corpuscular antigen, S-LPS or protein antigens .

The detection of circulating mycobacterium antigens using specific monoclonal antibodies (mAbs) has been shown to be a promising approach to the detection of active infection.
Recently, developed a simple and rapid dot- ELISA test based on IgG monoclonal antibody (TB-55 mAb) specific for a 55-kDa mycobacterial antigen and had been evaluated in the diagnosis of pulmonary as well as extrapulmonary TB .

The gold-standard screening method for LTBI is the tuberculin skin test (TST). The TST has several limitations, including the need for repeat visits and trained staff in addition to limited validity of the results. T-cell – based interferon-γ release assay are whole-blood enzyme-linked immunosorbentassay
(ELISA) and enzyme linked immunospot assay(ELISpot). The whole blood ELISA is available commercially as QuantiFERON-TB Gold and an “ intube ” variant, QuantiFERON-TB Gold In-tube . This Tcell-based assay for diagnosing tuberculosis infection gave promising results .

Human Q fever is currently diagnosed by clinical presentation and supporting serological responses against fixed, whole-cell phase I and phase II forms of the C. burnetii. The serological testing include immunofluorescence, complement fixation, enzyme- linked immunosorbent assay
(ELISA) and microagglutination.Q fever IgG ELISA is a specific alternative method for prevaccination testing and the diagnosis of Q fever. Worldwide, the most common method used in human diagnosis of
Q fever is the indirect immunofluorescence antibody
(IFA).

Detection of IgM antibody against the virus capsid antigen (VCA) is the best approach for the identification of primary EBV infection. Indirect immunofluorescence assay (IFA) of anti-VCA IgM and IgG antibody has been regarded as the golden standard for the serological diagnosis of
EBV infection, and other methods, such as enzyme-linked immunosorbent assays (ELISA) and chemiluminescent immunoassay (CLIA), were developed to improve the assay procedure.

Immunological methods such as antibody-capture enzyme-linked immunosorbant assay (ELISA) have been previously used for diagnosing TBM . The cell
ELISA method allows further confirmation of the results obtained by antibody-capture ELISA. The presence of a 30-kD protein antigen in CSF of TBM patients indicates that this protein carries the candidate marker antigen which is specific to M.
tuberculosis.

Statistical comparisons for cases of typhoid from
2003 to2008 admitted in Mansoura fever hospital
160 patient n number
140
120
100
80
60
40
20
0
2003 2004 2005 2006 2007 2008

35
Statistical comparisons for cases of brucella from 2003 to2008 admitted in Mansoura fever hospital patient n
30
25
20
15
10
5
0
2003 2004 2005 2006 2007 2008

7
6
5
9
8
4
3
2
1
0
Statistical comparisons for cases of tuberculosis from
2003 to2008 admitted in Mansoura fever hospital
Patient n number
2003 2004 2005 2006 2007 2008

12
Statistical comparisons for cases of meningitis from
2003 to2008 admitted in Mansoura fever hospital patient n
10
8
6
4
2
0
2003 2004 2005 2006 2007 2008