Mis-diagnosis of typhoid fever in Nigeria.

QUESTION TO BE ANSWERED

Mis-diagnosis of typhoid fever in Nigeria.


Is  widal test reliable ? 

Widal test is one of the most commonly and frequently used method in  clinical laboratories  to  make a presumptive diagnoses of enteric fever, commonly known as typhoid fever. widal test is not longer reliable in most  developed countries like the United states due to low prevalence of typhoid, access to safe drinking water and good laboratory practice. But this method is still in use in many developing countries like Nigeria where enteric fever is endemic. Typhoid fever  or enteric causes a major public health challenge that is associated with significant morbidity and mortality in many developing countries.


Enteric fever is  life threatening conditions caused by infection with  the bacterium salmonella typhi and S .paratyphi. Enteric fever is usually transmitted through food and drinks  contaminated with fecal materials. Enteric fever is associated with symptoms that may include high fever, fatigue, abdominal cramp, headache and rose spot and the symptoms are very similar with that of malaria. Early diagnosis and treatment of enteric fever are important to avoid serious complications that include intestinal bleeding also known as intestinal perforation.


In developed countries like US and china, testing for enteric fever usually involves  series of laboratory procedures like blood culture to detect the  bacteria during the first period or week of fever. other test like Stool, urine or bone marrow culture may also be performed. 


Salmonella enterica subsp. serotype typhi is the causative agent of  typhoid fever. currently, different types of diagnostic techniques are used in the endemic areas, but isolating the actual ethological  agent from stool, urine and blood is more reliable means of confirming an infection.


In developing countries like Nigeria, widal slide agglutination test is the common serological test  to diagnose typhoid fever. However, the world health organisation (WHO) has stated that  "widal tests should not be use as a diagnostic tool for typhoid". It suggest that a blood culture before initial antimicrobial therapy remains the best diagnostic method of choice, although isolation of salmonella from the bone marrow is the world standard method for confirming a typhoid fever.


Still, millions of Nigerians are being misdiagnosed with typhoid due to the rapid use of widal test as a diagnostic tool. the danger of incorrect diagnosis of typhoid fever is that the symptoms of typhoid or enteric fever  are difficult to distinguish from other hemorrhagic fever like malaria and yellow fever.Widal test had a low sensitivity and negative predictive value; it also had very low specificity and positive predictive value. It might be due to cross-reacting antibodies from other enterobacteria.  Low specificity means patients might be suffering from other causes of diseases and low PPV value means majority of those who tested have disease are not truly diseased by the suspected cause that is one of the reason why widal is not recommended in many developed countries.


#professionalize #Microbiology  #abbas/#siemuc

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