Janet Ogundepo
The National Association of Medical Laboratory have clarified that the validity of the Widal Test in typhoid fever diagnosis remains valid and cannot be questioned.
Stating this in an exclusive interview with PUNCH Healthwise, the AMLSN National President, Ifeanyi Casmir, highlighted the nation’s deficiency in efficient diagnostic testing for the ailment and noted that while some physicians have called for the abandonment of the Widal Test in favour of blood and stool culture alternatives, these alternatives are expensive and may only detect the typhoid parasite after it has been present in the body for an extended period of time.
Ifeanyi Casmir, National President Association of Medical Laboratory Scientists of Nigeria
Recently, some doctors and pharmacists on X, formerly Twitter, referred to the diagnosis of typhoid fever with the Widal Test as a scam and a “cash cow for lots of hospitals and labs.”
The medical practitioners argued that the test gives false positive or false negative results, stating that the blood culture is the mainstay for diagnosing typhoid fever at its early stages, adding that stool antigen, bone marrow culture and polymerase chain reactions were more appropriate in other contexts.
The PUNCH had in 2017, reported on some medical doctors’ stance that the widal test was not valid for clinical diagnosis and treatment of typhoid.
The doctors noted that 70 per cent of typhoid cases in Nigeria were as a result of misdiagnosis.
According to the World Health Organisation, typhoid fever is a life-threatening infection caused by Salmonella Typhi.
WHO
Typhoid fever, also called enteric fever, is spread through contaminated food or water.
When ingested, it multiplies and spreads into the bloodstream, creating symptoms like stomach pain, high fever, constant headache and diarrheal.
According to the Coalition Against Typhoid and Typhoid Vaccine Acceleration Consortium, Nigeria is a typhoid-endemic country with a burden of 291,909 cases (136 cases per 100,000) and 3,584 deaths recorded in 2019.
It further identified an increasing rate of multidrug-resistant typhoid strains in 2015.
An article on Enteric fever and other causes of fever and abdominal symptoms written by Jason Harris, and published in peer-reviewed scientific journal, Science Direct, states that widal tests were developed over 100 years ago, and remained one of the widely used diagnostic tests.
The author noted that the test detects antibodies in the blood sample against the O and H antigens of the bacteria but is limited in its sensitivity and specificity such that it could present a false-positive result, which could be from past infection or previous exposures to cross-reactive antigens.
The test results are measured in titres such that a titre of 1:80 or more for the O antibody and 1:160 or more for the H antigen indicated an infection.
However, a few studies on the reliability of the tests showed a relationship between the false positives of widal tests and antibiotic multidrug resistance.
Addressing criticisms of the widal test, Casmir clarified that the test can still be valuable as a screening tool for enteric fever when conducted and interpreted correctly.
He noted that relying solely on blood and stool culture tests may delay diagnosis and treatment, leading to poorer health outcomes for patients.
However, he cautioned against using the widal test as the sole basis for antimicrobial treatment, as this could contribute to antimicrobial resistance.
Casmir, who holds a PhD in molecular biology, said, “Whereas the widal test is not the gold standard for the diagnosis of enteric fever and microbial diseases, it is still useful as a screening tool and if used as a screening test, it must conform to standard protocols and its interpretation must be done rightly.
“No matter how well a test is done, the interpretation is what determines the use to which you can put the test. So if you don’t get the correct interpretation of the particular test, you have just wasted the patients’ resources and passed the patient through trauma.
“Widal as a screening test for enteric fever has its value, the problem is that in Nigeria, everyone claims to know how to do a widal test. The widal test is used to determine those who would be subjected to blood or stool culture tests or other further investigations including molecular testing.
“It is not supposed to be the basis to institute antimicrobial use because after a Widal Test result is obtained, antibiotics are given and this would promote antimicrobial resistance. How then do we know that the typhoid strain is susceptible to the antibiotics being administered?”
The President of AMLSN further clarified that achieving an accurate diagnosis of typhoid fever relies not only on laboratory tests but also on factors such as the stage of the infection when the patient seeks medical attention and the detailed medical history provided by the attending physician.
He further explained, “For you to say a widal test is right or wrong, you must be able to establish a two to three fold titerite and if you are unable to provide it, the piece of information being provided is useless.
“If a patient walks into a hospital and the sample is drawn for a widal test and the result is sent to the doctor and treatment is predicated on that, that doctor is part of the problem.
“For you to use the widal test as a means of diagnosis, you must establish two to threefold titerite. So, do they subject the patient to the testing to determine this or do they do a one-off widal test and are condemning the process?
“We are operating in a poor resource setting but if we must continue to use that, as I don’t subscribe to thrashing it, we must develop standard protocol for the testing and develop interpretative standards for the test and we should take away charlatans from performing widal tests.”
Casmir further decried the proliferation of medical diagnostic labs by quacks, noting that most diagnostic tests performed in most Primary Health Care centres were done by people who are not medical scientists.
He urged the National Primary Health Care Development Agency to intervene in the laboratory component in the primary health care centres, promising the support of the AMLSN.
He also called on the government to fully empower the Medical Laboratory Council of Nigeria to regulate laboratory facilities and practitioners, stating that the negligence of this has led to the prevalence of substandard testing materials in the country.
In light of the public health challenge posed by enteric fever in Nigeria, Casmir called for urgent action to address the shortcomings in the country’s diagnostic system and ensure access to accurate and timely testing for all patients.
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