Evaluation Of Blood Collected From Clinically Diagnosed Typhoid Fever Patients In The Metropolis Of Lagos, Nigeria
AbstractOver a period of 15 months, a total number of 635 clinically diagnosed typhoid fever patients and 100 healthy volunteers attending some public and government recognized health institutions in Lagos metropolis were bled and screened for Salmonella agglutin is, malaria parasitaemia and bacterial culture.
Out of the 635 patients, 505 (79.5%) were positive for Widal agglutination test using 1:160 as the cut-off antibody titre as determined in the screened sera of the healthy volunteers. Blood culture revealed that 216 (42.8%) bacterial pathogens were isolated from the Widal positive patients yielded out of which 101 (46.8%) isolates were of Salmonella sp. And 115 (53.2%) isolates of other bacteria of the family enterobacteriaceae. Among the Salmonella sp., 68(67.3%), 17(16.8%) and 16(15.8%) were S. typhi, S. paratyphi and S. arizonae respectively while the other enteric pathogens had 31 (27.0%), 29(25.2%), 23(20.0%), 14(12.2%), 10(8.7%), 5(4.3%) and 3(2.6%) isolates for Proteus sp., Klebsiella sp., Shigella sp., Pseudomonas aeruginosa, Escherichia coli, Haffinia sp. and Citrobacter sp. respectively. Malaria parasitaemia was demonstrated in the blood of 188 (37.2%) of Widal positive patients.
Our findings implied that a positve Widal agglutination test of a clinically diagnosed patient does not necessarily confirm a true S.typhi and S. paratyphi infections since other enteric bacteria as well as malaria parasites mimics both the 'O' and 'H' Salmonellae-antigens that form the core of Widal agglutination test kits. We therefore suggest the culturing of blood samples from all clinically suspected cases of typhoid and paratyphoid fever irrespective of the Widal agglutination antibody titre, so also is the necessity of performing malaria-parasite test particularly, in the malaria endemic regions of the globe, before proceeding on any antimicrobial therapy.
This suffice to say that exclusive reliance on serology for the diagnosis of this febrile disease can be misleading as individuals with preaxial are assumed and erroneously treated for typhoid fever based on single Widal agglutination test, whereas potential fatal illness such as malaria and other parasitaemia, non-typhoid salmonellosis, endocarditis and other gastro-intestinal infections may have been responsible.
We are therefore, through our findings, of the opinion that bacteriological confirmation of typhoid fever cases remains the most definitive diagnostic procedure particularly in Nigeria.
Key Words: Typhoid and paratyphoid fever, Widal agglutination test, culture, S.typhi, S. paratyphi, malaria paradise.
[J. of the Nig. Infection Control Assn. Vol.3(2) 2000: 25-30]