Epidemiology of intestinal helminthiasis among school children with emphasis on Schistosoma mansoni infection in Wolaita zone, Southern Ethiopia.

BACKGROUND: Intestinal helminth infections are major parasitic diseases causing public health problems in Ethiopia. Although the epidemiology of these infections are well documented in Ethiopia, new transmission foci for schistosomiasis are being reported in different parts of the country. The objective of this study was to assess the prevalence of Schistosoma mansoni and other intestinal helminth infections among school children and determine the endemicity of schistosomiasis in Wolaita Zone, southern Ethiopia. METHODS: Cross-sectional parasitological and malacological surveys were conducted by collecting stool samples for microscopic examination and snails for intermediate host identification. Stool samples were collected from 503 children and processed for microscopic examination using Kato-Katz and formalin-ether concentration methods. Snails collected from aquatic environments in the study area were identified to species level and Biomphalaria pfeifferi snails, the intermediate host of S. mansoni,, were individually exposed to artificial light in order to induce cercariae shedding. Cercariae shed from snails were used to infect laboratory-bred Swiss albino mice in order to identify the schistosome to species level. RESULTS: The overall prevalence of intestinal helminth infections was 72.2% among school children. S. mansoni infection prevalence was 58.6%. The prevalence and intensity of S. mansoni infections varied among schools and sex of children. Swimming was the only factor reported to be significantly associated with S. mansoni infection (AOR = 2.954, 95% CI:1.962-4.449). Other intestinal helminth species identified were hookworms (27.6%), Ascaris lumbricoides (8.7%), E. vermicularis (2.8%), Taenia species (2.6%), T. trichiura (1.2%) and H. nana (0.6%). Only B. pfeifferi snails collected from streams shed schistosome cercariae and 792 adult S. mansoni worms were harvested from mice exposed to cercariae shed from B. pfeifferi on the 6th week post-exposure. CONCLUSION: The present study found high level of intestinal helminth infections in the study area. The study also confirmed autochthonous transmission and endemicity of S. mansoni as evidenced by both parasitological and malacological findings as well as by further establishing infections in lab-bred mice. Therefore, there is a need to include the area in the control programs with anti-helminth drugs and also consider other complementary measures including sanitation, provision of clean water supply, and snail control.

Knowledge, attitudes and practice of communities of Wolaita, Southern Ethiopia about long-lasting insecticidal nets and evaluation of net fabric integrity and insecticidal activity.

BACKGROUND: Optimal use of long-lasting insecticidal (LLINs) for malaria prevention depends on mass distribution, the users' perception and behaviour of local malaria vectors. This study was aimed at assessing knowledge, attitude and practice (KAP) of communities about LLINs and fabric integrities and insecticidal activities of nets under use in Wolaita zone, Sothern Ethiopia. METHODS: Semi-structured interview questionnaires were used to collect data on KAP variables and WHO cone bioassay was used to test the insecticidal activity of sampled nets against an insectary colony of Anopheles arabiensis. Holes and repairs on surfaces of sample nets were counted and categorized following WHO guidelines to assess their fabric integrities. Chi-square (χ(2)) tests were used to verify associations between the demographic profiles of the respondents and their responses to KAP questionnaires. RESULTS: Out of a total of 770 household heads interviewed, 323 (42%) and 447 (58%) were males and females, respectively. The average family size in the surveyed households was 5.25 (±0.70 SE, range 1-12). The majority (81.1%) of the households owned at least one LLIN. The average numbers of LLINs being used and sleeping places in the households were 1.61 (0.04 SE, range 0-4) and 2.27(0.03 SE, range 1-6), respectively. Most of the respondents (n = 687; 89.2%) believed LLINs prevent malaria by killing or acting as physical barriers against mosquitoes. About 21 and 14% of the respondents considered children under five years and pregnant women as priority groups for sleeping under LLINs. Households use LLINs consistently throughout the year (86.4%) and tuck nets into bedding materials while sleeping (90.1%). Physical inspection of fabric integrity of sampled LLINs revealed holes ranging from size 1 (0.5-2 cm) to size 4 (> 25 cm) mostly on lower ("right/left") surfaces. Moreover, most surfaces of sampled LLINs caused 100% knockdown and mortality on insectary colonies of Anopheles arabiensis. CONCLUSIONS: The overall knowledge, attitude and practice about LLINs were satisfactory in the study areas. However, the family size net ratio must be narrowed and attention needs to be given to malaria vulnerable groups (children < 5 years of age and pregnant women). Continuous monitoring and evaluation of use and durability (fabric integrity and insecticidal activity) of LLINs should be conducted to avoid misuse and associated attrition of nets before the intended period.