Diethylcarbamazine in the control of bancroftian filariasis in the Ok Tedi area of Papua New Guinea: phase 2--annual single-dose treatment.

The Phase 1 semiannual single-dose 6 mg/kg diethylcarbamazine (DEC) treatment program demonstrated a significant reduction for Wuchereria bancrofti in the Ok Tedi area of Western Province, Papua New Guinea. The rate of detectable microfilaraemia was effectively reduced from 39% to 11% and mean microfilarial (mf) densities from 79mf/20 microliters to 19mf/20 microliters. The Phase 2 annual single-dose treatment of 6mg/kg DEC not only maintained the gains made during Phase 1 but reduced the microfilaraemia rate to less than 5% by 1990, with mf densities remaining stable at less than 20mf/20 microliters, amongst all participating villagers screened within the 5 original villages. The annual treatment program was expanded into 7 remote villages not subject to any form of active vector control. The microfilaraemia rate in these villages declined from 41% before treatment to 17% after only two annual administrations of 6mg/kg DEC, and mf blood densities were reduced from 71mf/20 microliters to 20mf/20 microliters. As was observed in the 5 original villages participating in the program, a significant reduction in splenomegaly associated with the DEC treatment was reported for the 7 villages in the expanded program during Phase 2; enlarged spleen rates were reduced from 50% (1986) to 32% (1990) and from 76% (1988) to 48% (1990), respectively. Malaria rates on the other hand increased slightly or remained stable. Malaria infections associated with W. bancrofti (mixed parasite infections) stimulated a greater splenic response than either parasite detected on its own.

Diethylcarbamazine in the control of splenomegaly associated with Bancroftian filariasis in the Ok Tedi area of Papua New Guinea.

Bancroftian filariasis is highly endemic in the Ok Tedi region of Papua New Guinea, with a reported mean rate of 39% before the implementation of a single-dose diethylcarbamazine (DEC) treatment programme in 1986. This was followed by a 72% decline in the rate of detectable microfilaraemia and a 40% reduction in pre- and post-treatment splenomegaly. No significant difference was observed when spleen enlargement was compared to the presence of patent malaria. A significant difference in splenomegaly was observed between DEC-treated villagers and their untreated counterparts. Significant differences were reported in the rate of detectable microfilariae of Wuchereria bancrofti, but not of malaria, between the two groups. The number of DEC administrations and the period of time since the first treatment played a significant role immunologically. Significant differences were observed in immunoglobulin (Ig) M and IgG levels and in the extent of splenomegaly between DEC-treated and untreated areas. Filarial infection associated with malaria resulted in higher spleen rates and size. W. bancrofti is a major contributor to splenomegaly in the Ok Tedi region, and splenomegaly associated with bancroftian filariasis can be reduced or controlled by low, well-spaced doses of DEC.

Chloroquine-resistant Plasmodium vivax in Papua New Guinea.

An Australian expatriate on regular weekly antimalarial prophylaxis with chloroquine base and Maloprim developed symptomatic Plasmodium vivax infection which failed to respond adequately to 600 mg of chloroquine base. More ominously, a resident of the Highlands region of Papua New Guinea contracted vivax malaria which failed to be cleared by 2400 mg chloroquine base administered over 4 d. Both patients had achieved appropriate blood and plasma concentrations of chloroquine after treatment. Chloroquine-resistant P. vivax is now a clinical fact in Papua New Guinea.

Diethylcarbamazine in the control of bancroftian filariasis in the highly endemic Ok Tedi area of Papua New Guinea: phase 1.

The effects of a well-spaced diethylcarbamazine (DEC) mass drug application in areas highly endemic for Wuchereria bancrofti in Papua New Guinea are not known. In 1986 a semi-annual single-dose 6 mg/kg body weight administration of DEC was initiated in the Ok Tedi area of Western Province, Papua New Guinea. The rate of bancroftian filariasis in the area was 39%. Within two years the rate of detectable microfilaraemia was reduced from 31% to 11% in the treated group. The mean blood density of the parasite was reduced from 79 to 19 microfilariae per 20 microliters. A survey of untreated villages in the immediate area (not surveyed before 1988) showed a filariasis rate of 39%. A 14-fold difference in the total microfilaraemia count was noted between the two groups when 1988 data were compared. A reduction in the annual rate of filariasis may be monitored through a well-established passive case detection program for malaria. The DEC treatment program was well accepted despite side-effects encountered in 20% of the treated population early on in the program. The success of the 2-year Phase 1 program has expanded into an annual single-dose administration of DEC over a larger area.

The monitoring of foodhandlers in Papua New Guinea.

In early 1987 guidelines were re-enforced for pre-employment medicals and 6-monthly health checks on foodhandlers in the Ok Tedi mining project in Papua New Guinea. The health monitoring program was stepped up as a result of two typhoid cases imported from the highlands and catering subcontractors failing to comply with the necessary pre-placement medicals for foodhandlers. Highlanders made up 28% (49/174) of the Ok Tedi catering department's workforce in 1987. The initial screen of 155 foodhandlers and 85 non-foodhandlers in February 1987 showed 6-7% of each group asymptomatically harbouring Salmonella spp. or Shigella spp. A second survey of 160 foodhandlers in August, including private fast-food establishments, detected only one Shigella boydii infection at a local fast-food-takeaway shop. Salmonella typhi was not detected in foodhandlers but was isolated from two non-foodhandlers recently returned from the highlands; in one case this resulted in a contact becoming infected at Tabubil. Infected persons were treated accordingly and foodhandlers were relieved of catering duties until follow-up cultures proved negative. Helminth infections were detected in 38% (309/811) of the stool samples examined. The low prevalence of Ascaris lumbricoides (2.5%) and Trichuris trichiura (1.1%) acquired locally, and a significant difference compared with outside groups supports the view that these species have recently been introduced to the North Fly (Ok Tedi) region. The majority of all Ascaris and Trichuris infections detected (61% and 73%, respectively) were found in highlanders, infection rates ranging from 3 to 15% depending on province of origin. Infections were treated accordingly to prevent possible transmission via food.(ABSTRACT TRUNCATED AT 250 WORDS)

Glucose-6-phosphate dehydrogenase deficiency and hereditary ovalocytosis in the Ok Tedi impact region of Papua New Guinea.

We report the distribution of two genetic traits, glucose-6-phosphate dehydrogenase (G-6-PD) deficiency and hereditary ovalocytosis (HO) in a number of populations living in the Ok Tedi impact region of Papua New Guinea. Significant interpopulation heterogeneity in the distributions of G-6-PD deficiency and HO was observed. The highlands populations of the region did not show any G-6-PD deficiency, but in the highlands fringe and lowland populations the trait has achieved polymorphic frequencies. Hereditary ovalocytosis is significantly more common in the region and is present in all the populations studied, including those in the highland valleys. Distribution patterns of the two genetic markers correspond well with the pattern of malaria endemicity in the region, providing support for the hypothesis that relates the distribution of these polymorphisms to that of malaria.