The study was carried out at Holy Family Hospital Akum, Santa Sub Division, Mezam Division of the North West Region of Cameroon. This area is made up of 12 quarters and has an estimated population of 5771 inhabitants whose occupation is mainly farming. The institution is situated along the Bafoussam Bamenda axis at mile 6 Akum and 17km from Bamenda town. The temperature of the area ranges from 20-21^oC. Farming is their main occupation due to the fertility of the soil. They engage in cattle rearing and cultivation of crops like corn, beans, Irish potatoes, etc. The hospital is well-known for the varied health services rendered to the public. The presence of modern equipment and a high influx of patients to the hospital from all areas of North West, West, Centre and Littoral Regions on daily bases makes the institution a good centre for research.

A descriptive cross-sectional study was conducted in April 2018. The study involved obtaining blood and stool samples from patients suspected of having typhoid fever. Blood samples were centrifuged to obtain serum that was subject to the Widal test. Stool samples were inoculated into BD Salmonella Shigella Agar (SSA) suitable for cultivation of Salmonella typhi.

Participants of this study were patients clinically diagnosed as having typhoid fever and who presented with fever of 38^oC and above, had bowel disturbance, headache, malaise, anorexia, etc, seeking medical attention at the Holy Family Hospital Akum. A total of 112 consented participants were enrolled in this study.

Only consented patients who presented with fever at the Holy Family Hospital Akum, aged 1 year and above were included in this study. Patients who had taken antibiotics say about a week before coming to the hospital, vaccinated individuals, those who did not present with fever and those age less than 1 year were excluded from the study.

Specimens were collected from patient > 1-year-old with symptoms of typhoid fever who presented themselves at the study site. They were asked to give verbal consent and answer brief questions about antimicrobial treatment, history of typhoid fever and vaccination. Guardians gave consent for minors. Specimens for this study were blood and stool for Widal and stool culture respectively.

5ml of blood was obtained from each study participant upon routine venepuncture for Widal test. Blood samples in plain tubes were allowed to clot and the clot removed by centrifuge and the supernatant obtained was serum.

Freshly passed faeces were collected in a sterile wide mouthed container. To avoid contamination, patients were given sterile papers to pass stool on it before picking a portion and putting in the sterile wide mouthed container. Each sample container was labelled with the patient’s code number, date and time.

A total of 112 patients presenting with febricity at the Holy Family Hospital Akum were enrolled in this study. A majority of these respondents were females, accounting for 64.3% while 35.7% were males. With respect to age distribution, the highest percentage was accounted for by those between 10 – 29 years old (n = 46) with 41.1%. This was followed by respondents between the age range 30 – 59 years (n = 36) with a percentage score of 32.1%. Respondents from 60 years and above came next with 19.7% (n = 22) while those from 9 years and below lasted with a frequency count of 8 and percentage score of 7.1% (Fig. 1).

Fig. (1). Age range distribution within respondents.

Fig. (2). Prevalence of typhoid fever according to sex.

Out of the 112 participants in this study, 64 were positive for typhoid fever based on the Widal test with an antibody titre of 1:80 for both “O” and “H” antigens being taken as cut off point values indicative of a recent typhoid infection giving a prevalence of 57.1%. 42.9% (n = 48) on the other hand were negative for typhoid fever when used Widal as the diagnostic tool. Interestingly, the prevalence of typhoid fever was 39.3% (n = 44) based on the findings from stool culture. A total of 60.7% were proven negative for typhoid fever (n = 68) based on the same findings from stool culture and still from the same sample under study (Table 1).

At 0.05 significance level, there was a statistically significant relationship between gender and Widal test outcomes within the study population (X² = 5.448, P = 0.020, df = 1). With respect to the Widal positive outcome, females dominated with 73.44% while males came with 26.56%, interval of 23.21 – 36.54 (OR = 0.393) (Fig. 2).

The same scenario was observed with stool culture results when compared between the gender variable. Females came highest with 54.55% as compared to males with 45.45%. With stool culture, females were 0.531 times more liable to be positive than males, despite the fact that there was no statistical significance between gender and stool at 95% confidence interval (X² = 2.995. P = 0.107, df = 1, CI = 28.35 – 39.95) (Fig. 2).

There was no statistical significance between age range within the respondents and Widal test outcome (X² = 2.633, P = 0.452). Respondents within the age range of 10 – 29 years dominated with Widal positive results with a percentage score of 37.50%. The least came from respondents with 9 years and below with a percentage score of 9.38% (Fig. 3).

Fig. (3). Prevalence of typhoid fever according to age.

The same thing was observed in stool culture where respondents from 10 – 29 years old dominated with 36.36% while those 9 years and below lasted with 5.88% (X² = 1.987, P = 0.575) (Fig. 3).

The sensitivity, specificity, negative and positive predictive values were computed for Widal test compared to the stool culture technique in the diagnosis of Salmonella species. Stool culture-confirmed typhoid cases were regarded as the “true positives” and all other febrile patients with stool culture outcomes as negative for S. typhi were also considered as the “true negatives” in this study. This means that since stool culture was considered the ideal to which Widal would be compared to, its sensitivity and specificity when cultured for S. typhi using the SSA were 100% each.

Widal sensitivity was 40.9% while its specificity was 32.4% as compared to the ideal 100% sensitivity and specificity of stool culture using the SSA (Table 2). The Positive Predictive Value (PPV) and Negative Predictive Value (NPV) of Widal were 28.13% and 6.44% respectively.

A total of 44 colonies on SSA were identified, all of which were further confirmed as motile Gram-negative rods. This accounted for 39.3% positive motility test, confirmed with the same 39.3% positivity in the KIA test (Table 3).

The findings in the present study suggest a high prevalence of 39.3% in patients using the stool culture method and a prevalence of 57.1% using the Widal test method. These high results concur with the study carried out by Gemechu and colleagues, which showed a high prevalence of typhoid fever (20%) using stool culture and 68.4% using Widal test method [7]. The high Widal prevalence in the present study could be associated with cross-reacting antibodies from febrile patients other than typhoid fever. In addition, the high prevalence of bacteria in the stool culture could be due to overcrowding with poor access to clean water and sanitation. Faecal matter may gain access into the water through runoff water or through sewage from sewers and pit latrines. This could have been a major contributing factor to the high prevalence considering that a number of patients use bushes to dispose of their faecal waste and urine.

Results from this study also showed that people of all ages are susceptible to infection by S. typhi. The age group more susceptible to the present study was those between 10-29 years old. These results concur with the study carried out by Ramyil and colleagues which showed that those between 24-29 years were more susceptible to typhoid fever [8]. This could be due to improper sanitation and hygiene. Both children and adults can get typhoid fever through ingestion of contaminated food and water. Travelling to high-risk destinations presents a high risk of contracting typhoid fever [9]. People living in overcrowded areas with poor access to safe drinking water and proper sanitation facilities are prone to infection by typhoid fever. Unlike in the present study where age was not significantly associated with S. typhi infection, a study by Lunguya and colleagues found that older age and longer duration of fever were predictive of typhoid fever [10].

A statistical significant relationship was found between gender and Widal test outcomes. With respect to the Widal positive outcomes, females dominated males meaning using the Widal test, females are more likely to be positive as compared to males. The same scenario was observed with stool culture results as females showed more positive than males. These findings contradict with the study carried by Youssef and colleagues which showed that the attack rates by S. typhi are similar for both men and women [11]. These findings also contradict with those of a study carried out by Ramyil and colleagues which showed that the males were more positive to Widal test and stool culture than females [8]. Some of the reasons why the present study showed more attack rates of S. typhi infection in females could be because women in this area are more involved in outdoor activities exposing them to high risk of infection.

Results demonstrated that Widal test had a low sensitivity and specificity of 40.9% and 32.4% respectively. These findings contrast with those of a study by Gemechu and colleagues which showed that Widal test had a high sensitivity of 84.2% and specificity of 35.5% [7]. False positives in the present study are possibly because the O and H agglutination usually appear around 8-12 days of infection. Hence, the probability of them not being detected during early diagnosis, and in immunosuppressed patients since they lack antibody responses. In the present study, a single sample test was used, as is the case in hospitals since outpatients rarely return for medical follow-up. This could be a drawback to interpreting the results, because of high background rates of circulating antibodies to S. typhi. Due to polyvalent nature of Widal antigens, there is a high possibility of cross-reactivity with bacterial and non-bacterial infections. Since some diseases such as malaria, ulcerative colitis, non-typhoidal Salmonella, rheumatoid arthritis and nephritic syndrome may show similar symptoms and produce high “O” antibody test, they should always be evaluated as differential diagnosis [12]. The base titre value of 1:80 may change in the population. So, the titre values may not have had much significance. The accurate antibody levels of individuals (Steady-state base lines titre) are difficult to establish. The case of many false positive in Widal test in the present study could be because individuals who had S. typhi infection in the past may have developed S. typhi antibodies during an unrelated or closely related infection, thereby giving false results.

The PPV and NPV of Widal test were low that is, 28.13% and 6.44% respectively. This means that out of the 57.1% reported cases of positive Widal in this study, the probability that subjects screened as positive truly had the disease was 0.28. The probability that subjects screened as negative using the Widal test truly were negative was 0.635. This contrast with that from a study carried out by Gemechu and colleagues which showed PPV and NPV of 24.6% and 90.0% respectively [7]. Though the PPV and NPV in this study were low, it indicates that Widal test was a slightly more better test to rule in the presence of the disease and a very poor method to rule out the presence of the disease.

Stool culture in the present study was considered the ideal to which Widal would be compared. Its sensitivity and specificity when cultured for S. typhi using the SSA were 100%. S. typhi is an enteric microorganism and its principal habitat is in the intestine of humans, so it is easily detectable in stool even in cases of early ingestion of bacteria [13]. Stool culture is important for diagnosis since it may be positive even when blood culture is negative and it is also important for the monitoring of carriage of S. typhi after apparent clinical cure, which is a risk factor for people involved.

In the present study, females were more susceptible to S. typhi infection than males which contrast findings in a study by Prajapati and colleagues where higher proportions of infection were observed in males than in females in Nepal [13]. The difference could be attributed to the fact that the study population in Nepal were children and outdoor activities more pronounced in males than in females in that area.

Stool culture was taken as an ideal test to which Widal would be compared. Stool culture is reliable, prompt and accurate since the 39.3% positive motility test was confirmed with the same 39.3% positivity in the KIA test whereas Widal test showed false positive and false negative results.