RESUMEN
A study was carried out in four villages of Makenene Sub-Division some 85 km north-west of Yaounde, between November 1993 and March 1994 to assess the prevalence and intensity of schistosomes and other helminth infections among senior primary school pupils aged 9-16. An extensive questionnaire was used to collect sociodemographic information and information on water-related activities. The overall prevalence of S. mansoni infection was 228 (23.6%) while S. haematobium infection was practically non-existent 03 (< 1%). Infection rates with intestinal nematodes were very high, up to 98% in some villages. Prevalence rates of schistosomiasis varied significantly (P < 0.05) between villages with the highest (36.2%) recorded in Makenene. Infections with other parasite species encountered were significantly different (P < 0.01) while a marked association was observed between water contact activities and the distribution of S. mansoni infections. However, S. mansoni infection intensities were not significantly different (P > 0.05) between those with a history of previous infection and treatment and those without.
Asunto(s)
Infecciones por Nematodos/epidemiología , Esquistosomiasis mansoni/epidemiología , Adolescente , Animales , Ascariasis/epidemiología , Camerún/epidemiología , Niño , Heces/parasitología , Femenino , Humanos , Incidencia , Masculino , Infecciones por Nematodos/orina , Prevalencia , Esquistosomiasis Urinaria/epidemiología , Esquistosomiasis Urinaria/orina , Tricuriasis/epidemiología , AguaRESUMEN
Two regions of the Jos Metropolis in Plateau State, Nigeria, with contrasting topographic features and harbouring many snails infested water bodies were surveyed for the presence of cercariae shedding Biomphalaria pfeifferi (Krauss) for a period of 12 months. A significantly marked (P < 0.01) fluctuation in infection rates in field B. pfeifferi was observed between the two areas. The factors contributing to the disparity in shedding capacities are linked to human behavioural pattern, and the drying up of water bodies. Their importance with respect to the control of intestinal schistosomiasis in the region are discussed.
Asunto(s)
Biomphalaria/parasitología , Vectores de Enfermedades , Schistosoma mansoni/crecimiento & desarrollo , Animales , Agua Dulce , Nigeria/epidemiología , Control de Plagas , Prevalencia , Esquistosomiasis mansoni/epidemiología , Esquistosomiasis mansoni/prevención & control , Esquistosomiasis mansoni/transmisión , Estaciones del AñoRESUMEN
The toxicity of an aqueous extract of Balanites aegyptiaca on Oreochromis niloticus was investigated. Fry of the fish were exposed to acute and sublethal concentrations of the extract in 96-h and 56-d static bioassays, respectively. Susceptibility of the extract on freshwater snail, Biomphalaria pfeifferi, was tested. The LC50 of the lethal concentrations of the extract on the fish and the snails were 1.12 mg/l-1 and 2.0 mg/l-1 respectively, while the effects of the sublethal concentrations on the growth rate and haematocrit percentage of the fish were determined. Signs of toxicosis such as air gulping, reduction in tailfin beating rate and overturning were observed in the fish before death occurred. The toxicant also reduced the growth rate and haematocrit percentage of the fish. The mode of action of the toxicant seems to be haemolytic or an impairment of osmoregulation in the blood leading to an over-dilution of the blood.
Asunto(s)
Perciformes , Extractos Vegetales/toxicidad , Animales , Biomphalaria/efectos de los fármacos , Peso Corporal/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Crecimiento/efectos de los fármacos , Hematócrito , Dosificación Letal Mediana , ÁrbolesRESUMEN
A preliminary crude screening of plants in Jos Metropolis showed that at a concentration of 100 mg/l-1 the stem bark extract of the Neem plant Azadirachta indica caused a 100 percent mortality when tested against three common snail intermediate host species, Biomphalaria pfeifferi, Bulinus truncatus, and Lymnaea natalensis after 24 hours exposure. Toxicity test with freeze-dried aqueous extract of the plant gave 96 hours LC50 values of 19.00 mg/l-1 (p > 0.05), 10.96 mg/l-1 (p > 0.05) and 15.13 mg/l-1 (p > 0.05) against B. pfeifferi, B. truncatus and L. natalensis, respectively. When a similar test was carried out on fish, Aphyosemon giardneri a 96 hour LC50 of 15.1 mg/l-1 was recorded. Extraction with alcohol, increase in temperature within the optimal range, increase in acidity of aquatic medium and cold storage improved the potency of the extract while boiling and room storage reduced it.
Asunto(s)
Vectores de Enfermedades , Peces/crecimiento & desarrollo , Moluscocidas , Extractos Vegetales , Caracoles , Animales , Biomphalaria , Bulinus , Agua Dulce , Lymnaea , Moluscocidas/toxicidad , Extractos Vegetales/toxicidadRESUMEN
5 brands of washing powders and a brand of local soap made in Nigeria were tested for toxicity to cercariae of the Nigerian strain of S. mansoni. The tests revealed that all washing soaps were super-toxic to cercariae at high concentrations, with soap bars being comparatively less toxic. The detergents killed all cercariae instantly at 250-4000 ppm while soap bars achieved the same effect between 3000-4000 ppm. At lower concentration 25-100 ppm, the detergents required less than 60 min to kill 100% of the cercariae while soap bars required less than 12 h. The 12 hours LC 50 and LC 90 for Omo (detergent) and local soap were determined. Also the effects of sub-lethal concentrations 1.25-10 ppm on the infectivity of cercariae in mice were evaluated. These tests revealed that the treatment suppressed infectivity and that the degree of suppression increased with increase in the sub-lethal concentration, 85.4% at 10 ppm as compared to 42.8% at 1.25 ppm.
Asunto(s)
Detergentes/farmacología , Schistosoma mansoni/efectos de los fármacos , Esquistosomiasis mansoni/prevención & control , Jabones/farmacología , Animales , Hematócrito , Hemoglobinas/análisis , Hígado/parasitología , Ratones , Nigeria , Recuento de Huevos de Parásitos , Esquistosomiasis mansoni/sangre , Esquistosomiasis mansoni/parasitologíaRESUMEN
Urine and faecal samples were obtained from 1,517 people in Fier, a typical rural village in Plateau State, Nigeria, for a parasitological survey among the population. 643 (42.39%) persons were found to be infected with altogether 9 helminths, namely: Ascaris lumbricoides, hookworm, Taenia sp., Trichuris trichiura, Enterobius vermicularis, Schistosoma mansoni, S. haematobium, Hymenolepis nana and Strongyloides stercoralis. Age and religion as opposed to sex, type of sewage system, and type of housing had a significant effect (P < 0.05) on the prevalence rates of the helminths in the population. Snail vector survey for schistosomatosis revealed the presence of Bulinus (Bulinus) truncatus, Bulinus (Physopsis) globosus and Biomphalaria pfeifferi with the latter being the most common with brevifurcate cercariae, and xiphidiocercariae being the most common cercariae harboured by the snails.
Asunto(s)
Helmintiasis/epidemiología , Adolescente , Adulto , Factores de Edad , Animales , Niño , Preescolar , Vectores de Enfermedades , Femenino , Agua Dulce , Vivienda , Humanos , Lactante , Masculino , Persona de Mediana Edad , Nigeria/epidemiología , Prevalencia , Religión , Población Rural , Factores Sexuales , Caracoles/parasitología , Cuartos de BañoRESUMEN
In Nigeria, little information is available on the distribution and ecology of fresh water snails as vectors of helminths. The authors have enumerated five species, the frequency of occurrence of which is exposed and discussed. No environmental factors seem to affect their distribution. Investigations are still continuing.