Human intestinal helminth contamination in pre-washed, fresh vegetables for sale in major markets in Ogun State, southwest Nigeria

Abstract

Fresh vegetables and fruits are essential components of a healthy and nutritious diet, but if consumed raw without proper washing and/or disinfection, can be important agents of transmission of enteric pathogens. This study determined human intestinal helminth contamination in pre-washed, fresh vegetables and fruits for sale to the human public, in four major markets in Ogun State, southwest Nigeria. Normal physiological saline washings from 250 g samples were processed using standard parasitological techniques and examined microscopically. Eighty one (8.44%) of the total 960 samples from 10 vegetables and fruits were contaminated with helminth eggs and/or larvae: Ascaris lumbricoides (4.58%), Trichuris trichiura (3.96%), hookworms (1.56%), Taenia/Echinococcus sp. (1.25%), Strongyloides stercoralis (0.73%), Enterobius vermicularis and Hymenolepis nana (0.42% each). Lettuce samples were most commonly contaminated (14.58%) followed by spinach (13.54%), green onions (10.42%), fluted pumpkin and carrot (9.38% each), cabbage (7.29%), tomatoes (6.25%), cucumber (5.21%), watermelon (5.21%) and green pepper (3.13%). H. nana and E. vermicularis were not detected in samples from Abeokuta and Ijebu-Ode markets, respectively. Helminth contamination was not significantly associated with market (χ2 = 10.834; p = 0.998) or season of purchase (χ2 = 0.583; p = 1.000). There were no statistically significant differences in overall prevalences of contamination between samples bought during the rainy (7.50%) and dry (9.38%) seasons (t = 5.014; p = 0.001) and between samples from the different markets (F = 0.389; p = 0.762; Sango-Ota, 9.58%; Ijebu-Ode, 8.75%; Sagamu, 7.92%; and Abeokuta, 7.50%). Burdens of helminth contamination were highest in lettuce and spinach samples from Sango-Ota market (2.50 ± 5.80 and 2.25 ± 5.16, respectively). Implications of study findings on human and public health are discussed.