Comparative field evaluation of residual-sprayed deltamethrin WG and deltamethrin WP for the control of malaria in Pahang, Malaysia.

The bioefficacy of indoor residual-sprayed deltamethrin wettable granule (WG) formulation at 25 mg a.i./m2 and 20 mg a.i./m2 for the control of malaria was compared with the current dose of 20 mg/m2 deltamethrin wettable powder (WP) in aboriginal settlements in Kuala Lipis, Pahang, Malaysia. The malaria vector has been previously identified as Anopheles maculatus. The assessment period for the 20 mg/m2 dosage was six months, but for the 25 mg/m2 dosage, the period was 9 months. Collections of mosquitoes using the bare-leg techniques were carried out indoors and outdoors from 7:00 PM to 7:00 AM. All mosquitoes were dissected for sporozoites and parity. Larval collections were carried out at various locations to assess the extent and distribution of breeding of vectors. A high incidence of human feeds was detected during May 2005 and a low incidence during January 2005 for all the study areas. Our study showed that deltamethrin WG at 25 mg/m2 suppressed An. maculatus biting activity. More An. maculatus were caught in outdoor landing catches than indoor landing catches for all the study areas. The results indicate that 25 mg/m2 WG is good for controlling malaria for up to 9 months. Where residual spraying is envisaged, the usual two spraying cycles per year with 20 mg/m2 deltamethrin may be replaced with 25 mg/m2 deltamethrin WG every 9 months.

Susceptibility of Mansonia uniformis to Brugia malayi microfilariae from infected domestic cat.

Microfilariae of Brugia malayi is transmitted to man and other susceptible hosts via mosquito. The transmission of B. malayi from cat to man by Ma. uniformis bite has never been reported. The Ma. uniformis mosquito is the normal vector for Wuchereria bancrofti but has never been reported as a vector for B. malayi, or a susceptible host for the growth and development of the microfilariae of B. malayi. The purpose of this study was to examine the development of B. malayi in Mansonia uniformis after feeding on the blood of an infected cat in the laboratory. The B. malayi infected cat was identified using PCR with the primers Bm-1/Bm-2 on DNA (at 10 ng/50 microl) extracted from the WBC of the cat. W. bancrofti was employed as a negative control. The sensitivity of the B. malayi DNA detection by PCR was 0.0001 ng. Adult Ma. uniformis mosquitos at the ages of 5, 10, and 15 days, 100 mosquitos in each group, were fed on the infected cat blood. Recovery of third stage microfilariae was found to be the highest in the 5-day old mosquito group (48%), followed by the 10- and 15-day old mosquito groups (32% and 18%, respectively). The mean number of B. malayi microfilariae found in thorax, head, and abdomen of the mosquitos were composed. The 5-day old (40.3%) and 10-day old (41.9%) mosquitos were significantly more susceptible to microfilariae than the 15-day old mosquitos (17.8%) (p-values using the Scheffe method: 0.027 and 0.039, respectively). There was no significant difference in the mean number of microfilariae in the thorax (p = 0.482) by age, but the mean numbers of microfilariae in the heads, and abdomens were significantly different by age between the 5- and10-, and the 15-day old mosquitos (p < 0.001 and p = 0.004, respectively).

Communal use of integumental wounds in honey bee (Apis mellifera) pupae multiply infested by the ectoparasitic mite Varroa destructor

The ectoparasitic bee mite, Varroa destructor, is highly adapted to its natural and adopted honey bee hosts, Apis cerana and Apis mellifera. Adult females perforate the integument of bee pupae in such a way that they and their progeny can feed. We examined the wounds that founder females made, and usually found one, and rarely up to three, integumental wounds on pupae of A. mellifera multiply infested by V. destructor. The punctures were mainly on the 2nd abdominal sternite of the host. These perforations are used repeatedly as feeding sites by these hemolymph-sucking mites and by their progeny. The diameter of the wounds increased during pupal development. In brood cells containing 4-5 invading female mites and their progeny, healing of the wound is delayed, normally occurring just before the imaginal moult of the bee pupa. These wounds are subject to microbial infections, and they are relevant to the evolution of behavioral traits in these parasitic mites and their relations to host bees.

Two human cases of tick bite caused by Ixodes nipponensis

We report two human cases of tick bite. A 63-year-old male had a pruritic pea-sized brownish nodule on the left popliteal area. Another 41-year-old male had an asymptomatic bean-sized black nodule in the pubic area. The ticks were identified as Ixodes nipponensis, which are the 18th and the 19th cases in Korea.