Cercarial Density in the River of an Endemic Area of Schistosomiasis Haematobia in Kenya

Ngethe D. Muhoho Centre for Microbiology Research, Kenya Medical Research Institute, Department of Parasitology, Institute of Tropical Medicine, Nagasaki University, Department of Parasitology, School of Medicine, Fukuoka University, Nairobi, Kenya

Search for other papers by Ngethe D. Muhoho in
Current site
Google Scholar
PubMed
Close
,
Tatsuya Katsumata Centre for Microbiology Research, Kenya Medical Research Institute, Department of Parasitology, Institute of Tropical Medicine, Nagasaki University, Department of Parasitology, School of Medicine, Fukuoka University, Nairobi, Kenya

Search for other papers by Tatsuya Katsumata in
Current site
Google Scholar
PubMed
Close
,
Eisaku Kimura Centre for Microbiology Research, Kenya Medical Research Institute, Department of Parasitology, Institute of Tropical Medicine, Nagasaki University, Department of Parasitology, School of Medicine, Fukuoka University, Nairobi, Kenya

Search for other papers by Eisaku Kimura in
Current site
Google Scholar
PubMed
Close
,
David K. Migwi Centre for Microbiology Research, Kenya Medical Research Institute, Department of Parasitology, Institute of Tropical Medicine, Nagasaki University, Department of Parasitology, School of Medicine, Fukuoka University, Nairobi, Kenya

Search for other papers by David K. Migwi in
Current site
Google Scholar
PubMed
Close
,
Wilfred R. Mutua Centre for Microbiology Research, Kenya Medical Research Institute, Department of Parasitology, Institute of Tropical Medicine, Nagasaki University, Department of Parasitology, School of Medicine, Fukuoka University, Nairobi, Kenya

Search for other papers by Wilfred R. Mutua in
Current site
Google Scholar
PubMed
Close
,
Francis M. Kiliku Centre for Microbiology Research, Kenya Medical Research Institute, Department of Parasitology, Institute of Tropical Medicine, Nagasaki University, Department of Parasitology, School of Medicine, Fukuoka University, Nairobi, Kenya

Search for other papers by Francis M. Kiliku in
Current site
Google Scholar
PubMed
Close
,
Shigehisa Habe Centre for Microbiology Research, Kenya Medical Research Institute, Department of Parasitology, Institute of Tropical Medicine, Nagasaki University, Department of Parasitology, School of Medicine, Fukuoka University, Nairobi, Kenya

Search for other papers by Shigehisa Habe in
Current site
Google Scholar
PubMed
Close
, and
Yoshiki Aoki Centre for Microbiology Research, Kenya Medical Research Institute, Department of Parasitology, Institute of Tropical Medicine, Nagasaki University, Department of Parasitology, School of Medicine, Fukuoka University, Nairobi, Kenya

Search for other papers by Yoshiki Aoki in
Current site
Google Scholar
PubMed
Close
Restricted access

The cercarial density in natural water and number of infected Bulinus globosus were monitored over a one-year period to identify the transmission foci in an endemic area of schistosomiasis haematobia in Kenya. Overall prevalence and intensity of infection of the study community were 59.2% and 10.9 eggs/10 ml of urine. Cercariometry was carried out on 456 occasions at 20 study sites while snail sampling was done on 465 occasions at the same sites over a one-year period. Cercariometry was exclusively done at flowing water habitats. The results showed the focality and seasonality of transmission. Cercariae were detected on 44 occasions at 11 sites. The detections were made on seven occasions at two study sites, six occasions at one site, four occasions at four sites, three occasions at one site, two occasions at two sites, and one occasion at one site. Densities of 1–4 cercariae/100 liters of water were found on 31 occasions. Five to nine cercariae/100 liters of water were found on seven occasions, 10–19 cercariae/100 liters of water were found on two occasions, and high cercarial densities greater than 20 cercariae/100 liters of water were found on four occasions. The highest count was 52 cercariae/100 liters of water. The presence of cercariae in natural water was shown to depend on the water temperature, but the intensity and duration of sunlight did not affect the presence of cercariae in water. The monthly variability of cercarial density was proportional to the number of infected snails. Cercarial density was highest in March and April, in the middle of the rainy season, whereas no cercariae were detected in cool dry season. The snail population peaked late in March, the beginning of the long rainy season, remained high for two months, and decreased rapidly late in May when heavy rain occurred. The overall infection rate of snails was 7.3% and the majority of infected snails were collected from March to May. There was no definite correlation between the presence or absence of cercariae and infected snails. Cercariae were frequently found where infected snails were absent and cercariae were sometimes absent where infected snails were present. Cercariometry and snail sampling remain quite complementary in identifying the transmission foci of schistosomiasis.

Author Notes

Save