Long-term follow-up of treatment with diethylcarbamazine on anti-filarial IgG4: dosage, compliance, and differential patterns in adults and children.

We have followed a population in an area endemic for Brugia malayi for three years after intensive treatment with diethylcarbamazine (DEC). Microfilariae were cleared from the circulation within four months in all eligible study participants (n = 60). There appeared to be a strong correlation between the maximum reduction in specific IgG4 and the number of days drug was taken under supervision (p = 0.41, P < 0.001), indicating that high total dosage of DEC is necessary for optimal reduction of active infection. In individuals with good compliance (at least 180 mg/kg of body weight, n = 34), we observed variable IgG4 patterns. All pre-treatment IgG4+ children (9-14 years old) and 40% of the IgG4+ adult population (> or = 15 years old) showed a gradual decrease in anti-filarial IgG4; 53% of these showed complete clearance of worm burden by the end of the study. In contrast, another group of male IgG4+ adults showed IgG4 patterns that started to increase between nine months and two years after treatment, indicating either a partial efficacy of DEC that allowed recovery of resident adult worms or reinfection.

Regulation of anti-filarial IgE by infection pressure.

In lymphatic filariasis, specific IgG4 responses to the parasite and their relationship with infection have been studied extensively, but only a few studies have concentrated on anti-filarial and total IgE. Here we have investigated the role of filarial infection pressure on production of IgE by considering length of exposure (age), filarial endemicity and parasitological status. Antibody levels were determined in 366 individuals, who were resident in 3 villages in South-Sulawesi, Indonesia, with varying degrees of filarial transmission intensity, as indicated by the prevalence of Brugia malayi microfilaraemia (0.7%, 9% and 32%, respectively). Anti-filarial IgE levels were significantly lower in the low transmission village than in the areas with intermediate and high filarial transmission; however, in the latter village a remarkable suppression of specific IgE was found. Microfilaria-positive individuals showed elevated levels of total IgE, but suppression of specific IgE, which has been reported before. Taken together, these observations suggest that 2 opposing mechanisms regulate anti-parasite IgE expression: increasing experience of filarial infection stimulates specific IgE, but antibody levels become specifically suppressed when microfilariae or adult worms develop. Using a simple mathematical model, we illustrate how anti-filarial IgE increases with parasite antigen up to a threshold level, but levels off and becomes down-regulated after the threshold is exceeded.

Two new nematode species of Bunomystrongylus n. gen. (Trichostrongylina:Heligmonellidae) collected from Bunomys spp. (Rodentia:Muridae) of Sulawesi, Indonesia.

Bunomystrongylus n. gen. (Nematoda: Heligmosomoidea: Heligmonellidae: Nippostrongylinae) was proposed, and 2 new species, Bunomystrongylus abadii n. sp., the genotype, from Bunomys penitus and Bunomystrongylus miyagii n. sp. from Bunomys andrewsi, both collected in Sulawesi, Indonesia, were described. This genus is distinguished from other genera of Nippostrongylinae by the peculiar synlophe having round ridges without intracuticular supports on dorsal to left lateral fields in midbody, the extremely long filiform spicules, and the complexly coiled vestibule. Bunomystrongylus abadii differs from B. miyagii by having the right lobe of the bursa copulatrix larger than the left lobe, smaller length ratio of the spicules to body length, and a dorsal ray divided more distally. Bunomystrongylus is presumed to have derived from a common ancestor with Rattustrongylus and Hasanuddinia on the Asian continent and evolved on Sulawesi Island.

Prevalence of intestinal helminthic infections in Kao District, north Halmahera, Indonesia.

A parasitological survey was conducted on the inhabitants of six villages of Kao District, Halmahera Island, North Maluku, Indonesia, in July 1993. A total of 422 fecal samples were examined by using Kato-Katz thick smear, modified Harada-Mori culture and formalin ether concentration techniques. Seven nematode species, ie Ascaris lumbricoides, Trichuris trichiura, Necator americanus, Ancylostoma duodenale, Strongyloides stercoralis, Enterobius vermicularis and unidentified rhabditoids of free-living nature, were detected. Trematode and cestode infection was not proven. Necator americanus was the predominant species of hookworm. Soil-transmitted nematode infections were highly prevalent. Among the young inhabitants aged less than 15, positive rates of Ascaris, Trichuris and hookworm infections were 32.7, 52.7 and 68.6%, respectively. Among the people aged 15 or more, the positive rate for hookworm (85.9%) was much higher than that for Ascaris and Trichuris (13.5 and 40.5%, respectively). Egg count revealed that more than 90% of inhabitants with Trichuris or hookworm had light infections. The latrines in the surveyed area seemed to have only limited effects on the improvement of the parasitological status because the prevalence of Trichuris infections was much higher in a village where most houses were provided with latrines. These conflicting conditions were considered to have been caused by many factors including the inadequate structure of the latrines.

Intestinal parasitic infections in Campalagian district, south Sulawesi, Indonesia.

Intestinal parasitic infections were surveyed in the inhabitants of 3 coastal and 2 inland villages of Campalagian District, South Sulawesi, Indonesia, in July 1992. A total of 398 fecal samples were examined by using Kato-Katz thick smear, Harada-Mori culture and agar-plate culture techniques. Protozoan cysts were examined by formalin ether concentration technique on 380 fecal samples. Soil-transmitted helminth infections were highly prevalent with the overall positive rates as follows: Ascaris lumbricoides 25.3%, Trichuris trichiura 59.3%, hookworm 68.3% and Strongyloides stercoralis 2.3%. Eight species of protozoan were detected with the overall prevalence as follows: Entamoeba histolytica 10.9%, E. hartmanni 16.3%, E. coli 31.9%, Endolimax nana 12.5%, Iodamoeba buetschlii 5.4%, Giardia lamblia 4.6%, Chilomastix mesnili 0.8% and Blastocystis hominis 18.0%. In the inland villages, prevalence of hookworm infection was higher than Ascaris and Trichuris infections, while in the coastal villages Trichuris infection was predominant. Egg count revealed that the infection level was light in most of the hookworm and Trichuris carriers. Prevalence of lavatories among houses appeared to be inversely proportional to the prevalence of hookworm infection. Meanwhile, the incomplete structure of the lavatories might result in contamination of environment with Ascaris and Trichuris eggs. Harada-Mori culture was the most efficient method in the detection of hookworm infection compared to other techniques. Both Necator americanus and Ancylostoma duodenale were found in all villages, but the former was the predominant species. An adult pinworm was detected by agar-plate culture of feces. Two types of pinworm males, corresponding to Enterobius vermicularis and E. gregorii, were observed.

Enzyme-linked immunosorbent assay for diagnosis of human strongyloidiasis.

Crude antigen (CA) was prepared from Strongyloides stercoralis filariform larvae obtained from in vitro culture of the human feces containing rhabditiform larvae. The lyophilized filariform larvae were ground and ultrasonicated in distilled water then the soluble antigenic preparation was delipidized. The protein content of the crude soluble antigen was 20% of the original dried larvae. The CA was passed through a gel filtration chromatography column and yielded three different protein fractions namely F1, F2 and F3. CA and its fractions were used in the indirect enzyme-linked immunosorbent assay (ELISA) for detecting antibodies to S. stercoralis in serum samples of 5 groups of individuals. These were patients with parasitologically confirmed strongyloidiasis (group 1), patients with mixed S. stercoralis and other parasitic infections (group 2), non-strongyloidiasis patients with other worm infestation(s) (group 3), normal parasite-free Thais (group 4) and normal parasite-free Swedes (group 5). It was found that F2 was the best antigen in the ELISA. The sensitivity, specificity and positive and negative predictive values of the test using F2 as the antigen were 95.0%, 96.4%, 95.0% and 96.4%, respectively.