Prevalence of Plasmodium falciparum and Salmonella typhi Infection and Coinfection and Their Association With Fever in Northern Tanzania

Abstract

Background: Plasmodium falciparum and Salmonella typhi are major causes of fever in the tropics. Although these infections are caused by different organisms and are transmitted via different mechanisms, they have similar epidemiologic and clinical features. This study aimed to determine the prevalence of S. typhi and P. falciparum infections and their associations with fever at 2 sites in Northern Tanzania.

Methods: This was a community-based, cross-sectional study, conducted from February to June 2016, involving 128 randomly selected individuals, aged between 1 and 70 years. Sixty-three (49.2%) participants were recruited from Bondo Ward, Tanga Region, and 65 (50.8%) were recruited from Magugu Ward, Manyara Region. Blood samples were collected by venepuncture into sterile microtubes. Detection of pathogen DNA was achieved via a multiplex real-time polymerase chain reaction assay. Data analysis was done using Stata, version 14. Prevalence data were presented as numbers and percentages, and chi-square analysis was used to assess associations. P values of .05 or less were considered statistically significant.

Results: Of 128 participants, 31 (24.2%) and 17 (13.3%) tested positive for P. falciparum and S. typhi infection, respectively. Of the 63 participants from Bondo, 31 (49.2%) had P. falciparum parasitaemia. None of the participants from Magugu tested positive for Plasmodium parasitaemia. S. typhi bacteraemia was detected in 11 (17.5%) of 63 and 6 (9.2%) of 65 participants in Bondo and Magugu, respectively. P. falciparum–S. typhi coinfection was only detected in Bondo (n=6, 9.5%). Age was the only variable that showed a significant association with both P. falciparum and S. typhi infection; falling within the 5- to 9-year or 10- to 15-year age groups was associated with both infections (Χ²=2.1; P=.045). Among the 30 patients with Plasmodium parasitaemia, 7 (23.3%) had fever, whereas 2 (12.5%) of 16 patients infected by S. typhi had fever. P. falciparum infection (Χ²=12.4, P<.001) and P. falciparum–S. typhi coinfection (X²=5.5, P=.019) were significantly associated with fever, while S. typhi infection alone was not.

Conclusion: S. typhi and P. falciparum were considerably prevalent in the area. One-third of the P. falciparum–S. typhi coinfected individuals in Bondo had fever. P. falciparum infection was an important contributor to febrile illness in Bondo. In the presence of coinfections with P. falciparum and S. typhi, the use of malaria rapid diagnostic tests should be emphasised to reduce irrational use of medications.