Six months of Aedes aegypti control with a novel controlled-release formulation of pyriproxyfen in domestic water storage containers in Cambodia.

A field evaluation of a novel, 5% controlled-release formulation of pyriproxyfen was carried out in 400-500 liter concrete water storage jars, the most common and important larval habitat of the dengue vector, Aedes aegypti, in Cambodia. The formulation consisted of cylindrical resin strands, 3 mm in diameter and 40 mm in length. Pyriproxyfen was applied to 100 jars at a target dose of 0.03-0.04 mg of active ingredient (a.i.) per liter (30-40 ppb) in households in Phum Thmei, a village near the capital city of Phnom Penh, in April 2005. Inhibition of adult emergence (IE) in field populations ofAe. aegypti was measured every 2 weeks for 34 weeks. IE in treated jars exceeded 90% for 20 weeks, and remained above 80% until the end of the study. In 25 untreated jars, failure of pupae to metamorphose into viable adults remained below 4%. No alteration of taste or other undesirable effects of the treatment were reported by householders. This single treatment provided control of Ae. aegypti in water jars for the length of the main dengue transmission season in Cambodia that normally extends from May to November.

Intestinal parasites in school-aged children in villages bordering Tonle Sap Lake, Cambodia.

The objective of this study was to study Schistosoma mekongi and other intestinal parasitic infections, and intestinal symptoms and related complaints among school-age children and adolescents living around Tonle Sap Lake. Villages were selected where there were potential signs of schistosomiasis (hepatomegaly), and where subjects complained of intestinal symptoms. Stool samples were collected from 1,616 children and were examined by Kato-Katz, SAF concentration, and Baermann technique; short clinical examinations were also performed. No S. mekongi infection was detected, although a high level of intense human water contacts was reported. Helminth infection such as Ascaris lumbricoides (27.7%) and hookworms (29.7%) were common. Trichuris trichiura 4.4%), Hymenolepis nana (6.2%), Giardia lamblia (4.2%), and Entamoeba spp (14.4%) were also recorded. Strongyloides stercoralis was frequently diagnosed (20.2%). It was concluded that it is unlikely that S. mekongi is transmitted in Tonle Sap Lake. However, other intestinal parasitic infections are widespread. In particular, S. stercoralis should be considered an important etiologic agent in children and adolescents with abdominal complaints.

The first reported cases of canine schistosomiasis mekongi in Cambodia.

We have been conducting surveys of schistosomiasis mekongi along the Mekong river in Cambodia since 1997. We attempted to detect canine schistosome infection during the survey in 2000 because dogs were reported to be natural reservoirs of the Mekong schistosome in Lao PDR. A total of 28 canine fecal samples were collected in Kbal Chuor village, Kratie Province and examined for schistosome eggs. One specimen had schistosome eggs (positive rate = 3.6%; egg density = 100/gram stool), which showed characteristics of Schistosoma mekongi. During the 2001 survey, one out of 310 canine stool samples was positive for schistosome eggs (positive rate = 0.32%; egg density = 3,456/gram stool). These are the first confirmed cases of canine schistosomiasis mekongi in Cambodia, which suggests that dogs are animal reservoirs of S. mekongi in the survey area. We further tried to detect S. mekongi in cows, water buffalos, pigs,horses, and field rats in five villages in Kratie Province; no schistosome egg was found in the stools of these animals.