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Helminth eggs in sludge may pose significant health risks to exposed populations through direct or indirect contact. Helminth eggs were detected in 100% of pit latrine sludge tested, corroborating the study of Yen-Phi et al. (2010) in Vietnam. Berteigne (2012) estimated that about 900 to 1,350 m3 of untreated FS is discharged weekly into the peri-urban area of Yaounde (Cameroon). Thus, treatment is necessary to minimize the risk of helminth infection by excreta. This study revealed heterogeneity in the distribution of helminth species and the total helminth eggs (Table 2). The detection frequencies among individual helminth species varied significantly. Ascaris lumbricoides was detected in over 70% of all samples, which is in line with the results of previous studies (Koné et al. 2007; Yen-Phi et al. 2010), indicating a high prevalence of Ascariasis in the population. Indeed, observations by Nkengazong et al. (2010), assessing the prevalence of geohelminths in 420 Cameroonian pupils, revealed a high prevalence of Ascaris eggs. The predominance of Ascaris eggs in the sludge samples could also be explained by high egg production (200,000 eggs/day) and durable eggs (Feachem et al. 1983). The parasite Ankylostoma duodenale had the lowest detection frequencies (13.79%) (see Table 2). Nematodes represented 67% of the total species, followed by Trematodes and Cestodes. The helminth species prevalence (median values) found in samples were A. lumbricoides (41.4 eggs/g DM), A. duodenale (31.5 eggs/g DM), Fasciola hepatica (34.9 eggs/g DM), Trichuris trichiura (32.5 eggs/g DM), Strongyloides stercoralis (24.8 eggs/g DM), Taenia sp. (24.7 eggs/g DM), Enterobius vermicularis (22.7 eggs/g DM) and Hymenolepis nana (13.4 eggs/g DM). The diversity of helminth species found in the samples is in accordance with Jimenez et al. (2000), who characterized wastewater sludge in Mexico and Yen-Phi et al. (2010), who characterized FS in Vietnam. The high variability in terms of number and diversity of helminth eggs could be attributed to the health status of pit latrine users, the epidemiological conditions of the populations in the study area as well as the storage condition in the pit of the latrines. By assessing pathogens in septage in Vietnam, Yen-Phi et al. (2010) recorded a correlation between helminth ova concentration and retention time of FS. In Vietnam, in order to reduce human health risks associated with excreta use in agriculture, the Vietnamese Ministry of Health has stipulated the time for human excreta storage in latrines to be at least six months before application as fertilizer (Jensen et al. 2008). Strauss et al. (1997) reported the effect of storage duration on FS stabilization. The effects of retention time could not be applied to explain the prevalence and diversity of helminth eggs recorded in our study as pits were sampled while in use.

Table 2

Concentration of helminth eggs found in FS

  Median
Minimum
Maximum
Std deviation
Percentile
25
75
Helminth eggsnEggs/LaEggs/gbEggs/LaEggs/gbEggs/LaEggs/gbEggs/LaEggs/gbEggs/LaEggs/gbEggs/LaEggs/gb
Ascaris lumbricoides 21 16,667 41.4 667 1.9 36,667 90.3 11,039 26.8 6,667 13.9 21,833 60.9 
Ankylostoma duodenale 16,611 31.5 4,222 9.4 32,000 81.0 12,262 31.6 9,306 17.4 29,556 71.4 
Enterobius vermicularis 11 8,667 22.7 3,333 7.1 20,000 61.1 7,004 19.7 4,167 8.9 19,778 38.7 
Fasciola hepatica 16,222 34.9 1,111 2.8 30,000 66.8 9,098 20.3 10,778 20.1 18,889 37.5 
Hymenolepis nana 5,556 13.4 3,333 6.6 16,667 48.8 4,572 14.3 4,389 10.0 7,556 18.6 
Schistosoma mansoni 11,389 22.8 4,444 8.5 32,222 79.7 9,867 25.5 5,805 12.2 21,833 51.7 
Strongyloides stercoralis 13 10,889 24.8 4,333 8.5 40,889 107.2 11,838 27.5 7,333 18.9 18,778 37.0 
Taenia sp. 11 10,000 24.7 667 1.7 26,667 64.2 8,815 19.0 8,333 18.2 22,444 45.4 
Trichuris trichiura 13,444 32.5 4,445 9.3 22,889 67.0 8,432 22.7 5,945 17.5 20,722 56.0 
Total helminth eggs 30 33,222 81.1 37,778 8.5 100,889 264.5 30,522 74.5 15,222 38.9 70,889 155.2 
  Median
Minimum
Maximum
Std deviation
Percentile
25
75
Helminth eggsnEggs/LaEggs/gbEggs/LaEggs/gbEggs/LaEggs/gbEggs/LaEggs/gbEggs/LaEggs/gbEggs/LaEggs/gb
Ascaris lumbricoides 21 16,667 41.4 667 1.9 36,667 90.3 11,039 26.8 6,667 13.9 21,833 60.9 
Ankylostoma duodenale 16,611 31.5 4,222 9.4 32,000 81.0 12,262 31.6 9,306 17.4 29,556 71.4 
Enterobius vermicularis 11 8,667 22.7 3,333 7.1 20,000 61.1 7,004 19.7 4,167 8.9 19,778 38.7 
Fasciola hepatica 16,222 34.9 1,111 2.8 30,000 66.8 9,098 20.3 10,778 20.1 18,889 37.5 
Hymenolepis nana 5,556 13.4 3,333 6.6 16,667 48.8 4,572 14.3 4,389 10.0 7,556 18.6 
Schistosoma mansoni 11,389 22.8 4,444 8.5 32,222 79.7 9,867 25.5 5,805 12.2 21,833 51.7 
Strongyloides stercoralis 13 10,889 24.8 4,333 8.5 40,889 107.2 11,838 27.5 7,333 18.9 18,778 37.0 
Taenia sp. 11 10,000 24.7 667 1.7 26,667 64.2 8,815 19.0 8,333 18.2 22,444 45.4 
Trichuris trichiura 13,444 32.5 4,445 9.3 22,889 67.0 8,432 22.7 5,945 17.5 20,722 56.0 
Total helminth eggs 30 33,222 81.1 37,778 8.5 100,889 264.5 30,522 74.5 15,222 38.9 70,889 155.2 

aHelminth eggs per litre of sludge.

bHelminth eggs per gram of DM.

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