Challenges in the Diagnostic Performance of Parasitological and Molecular Tests in the Surveillance of African Trypanosomiasis in Eastern Zambia

Abstract

African animal trypanosomiasis (AAT) control programs rely on active case detection through the screening of animals reared in disease endemic areas. This study compared the application of the polymerase chain reaction (PCR) and microscopy in the detection of trypanosomes in cattle blood in Mambwe, a rural district in eastern Zambia. Blood samples were collected from 227 cattle and tested for infection with trypanosomes using microscopy and Ribosomal RNA Internal Transcribed Spacers (ITS)-PCR. Microscopy on the buffy coat detected 17 cases, whilst thin and thick smears detected 26 cases and 28 cases, respectively. In total, microscopy detected 40 cases. ITS-PCR-filter paper (FP) on blood spots stored on FP detected 47 cases, and ITS-PCR-FTA on blood spots stored on Whatman FTA Classic cards detected 83 cases. Using microscopy as the gold standard, ITS-PCR-FTA had a better specificity (SP) and sensitivity (SE) (SP = 72.2%; SE = 77.5%; kappa = 0.35) than ITS-PCR-FP (SP = 88%; SE = 60%; kappa = 0.45). The prevalence of Trypanosoma brucei s.l. was higher on ITS-PCR-FTA (19/227) than on ITS-PCR-FP (0/227). Our results illustrate the complexities around trypanosomiasis surveillance in rural Africa and provide evidence of the impact that field conditions and staff training can have on diagnostic results, which in turn impact the success of tsetse and trypanosomiasis control programs in the region.

The detection of African trypanosomes in goats reared in tsetse infested villages of Eastern Zambia

“…DNA from stored blood spots was extracted using the buffer technique as described by Morrison et al (2007). PCR was undertaken in 25 µl reaction mixtures containing primers ITS1 CF (5ʹ-CCG GAA GTT CAC CGA TAT TG-3ʹ) and ITS1 BR (5ʹ-TTG CTG CGT TCT TCA ACG AA-3ʹ), One Taq 2X master mix (New England BioLabs, Ipswich, MA, USA), nuclease free water and 5 µl of extracted DNA sample, all reagents procured from Inqaba Biotec, Pretoria, South Africa (Radwanska et al, 2002;Njiru et al, 2005;Mulenga et al, 2021).…”

Molecular identification and prevalence of trypanosomes in cattle distributed within the Jebba axis of the River Niger, Kwara state, Nigeria

“…However, several reports show the existence of atypical human infections caused by animal trypanosomes [ 10 – 14 ]. Therefore, identification of Trypanosoma species is fundamental to measuring the general threat posed by trypanosome species in animals and humans [ 15 , 16 ].…”

Policy and Linkages in the Application of a One Health System for Reporting and Controlling African Trypanosomiasis and Other Zoonotic Diseases in Zambia

“…Over 60% of the country's cattle population is under threat from trypanosomiasis with about 80% of the livestock owned by traditional farmers. The prevalence of trypanosomiasis in livestock and particularly in cattle has continued reporting alarming figures in affected areas [9][10][11]. According to data collected during a trypanosomiasis survey conducted in Mambwe district of eastern Zambia, AAT prevalence in cattle stood at 3.8% [12].…”

“…In sub-Saharan Africa, diagnostic capacity for many of the zoonotic diseases that are endemic in these countries is generally poor. According to studies conducted in Zambia, there is limited laboratory capacity for diagnosis of such diseases in literally all the provinces in the country [10,14,15]; thus, lack of effective diagnostic capacity and under diagnosis has been a critical weakness regarding effective treatment and control of infectious diseases. This challenge is mainly based on inadequate laboratory facilities and associated equipment and skilled laboratory personnel.…”

“…This challenge is mainly based on inadequate laboratory facilities and associated equipment and skilled laboratory personnel. This has affected the countries' capacity and efforts to deal with re-emerging and emerging zoonotic diseases such as trypanosomiasis [10,14,15,18].…”