Bancroftian filariasis in an isolated hunter-gatherer shifting horticulturist group in Papua New Guinea.

A survey for Wuchereria bancrofti microfilaraemia using membrane filtration was carried out among the Hagahai, a recently contacted Papua New Guinea group of hunter-gatherer shifting horticulturists. Adult men had a significantly higher microfilaraemia rate than women. Children aged > 15 years had significantly fewer infections than adults and the microfilaraemia densities were considerably lower. Two subjects exhibited matutinal microfilarial periodicity, peaking at approximately 06 h 00. The possible reasons for the epidemiological and microfilarial findings are discussed.

Impact of active immunisation against enteritis necroticans in Papua New Guinea.

Enteritis necroticans, known locally as pigbel, has been a major cause of illness and death among children in the highlands of Papua New Guinea. After a successful trial of active immunisation against the beta toxin of the causative organism, Clostridium perfringens type C, immunisation of children was begun in 1980. The effects of the immunisation programme on pigbel admissions in 3 of the 5 major highland hospitals were assessed. In each of the centres studied the proportion of admissions due to enteritis necroticans dropped significantly after immunisation was introduced (p less than 0.001) and hospital admissions for pigbel in 1984-86, when immunisation was well established, were less than one fifth of previous figures.

HTLV-I antibody studies in villagers in East Sepik Province, Papua New Guinea.

Serum samples collected in 1984 during a malariometric survey of two villages in the East Sepik Province of Papua New Guinea were tested for antibodies to HTLV-I. None of the villagers showed any symptoms suggestive of retrovirus infection. Eighteen of the 186 (9.5%) sera tested at that time were found to be positive. Blood samples were subsequently obtained from fifteen of the eighteen positives and subjected to analysis by enzyme-linked immunosorbent assay (ELISA), radioimmuno assay (RIA), radioimmunoprecipitation assay (RIPA), and Western blot (WB). Fourteen of the fifteen gave a positive ELISA response, but none were unequivocally positive by p 24 RIA. All sera tested were reactive to gag antigens by WB, but gave "indeterminate" results currently accepted criteria. Notably absent from the WB profiles of all of the study subjects was an antibody response to HTLV-I envelope protein gp 46. It is possible that these antibody responses are directed against a variant of HTLV-I or to a novel retrovirus which possesses core antigens similar to those of HTLV-I but has different envelope antigens. Until a virus is isolated, or the viral genome is identified in infected lymphocytes, the possibility remains that the response may be due to factors unrelated to retrovirus infection.

An affinity technique for the isolation of Clostridium perfringens type C from man and pigs in Papua New Guinea.

Necrotising enteritis caused by Clostridium perfringens type C (CwC) is an important cause of morbidity and death in highland regions of Papua New Guinea (PNG) and the organism is readily isolated from clinical cases. Although detected in fluorescent antibody stains of faecal cultures, CwC has previously only once been isolated from normal people or from pigs in PNG. The difficulty results from the greater numbers of the much more common Cl. perfringens type A (CwA) which is morphologically and culturally indistinguishable from CwC. Separation of CwC from the more numerous CwA has been achieved by utilising their antigenic dissimilarity. Silicate beads covered with specific antibody to CwC added to a mixed culture bound CwC cells while most of the unbound cells were washed away. When the beads were plated out type C organisms were recovered. In laboratory tests CwC was isolated from mixtures with CwA where the type A organisms predominated by one million to one. With this system type C organisms have been isolated from human and pig faeces from PNG.

Reinfection with intestinal helminths after treatment with mebendazole and fluctuations in individual Ascaris lumbricoides infections with time.

In a group of rural school children in the highlands of Papua New Guinea with an initial prevalence of Ascaris lumbricoides 71 per cent, Trichuris trichiura 69 per cent and Necator americanus (hookworm) 95 per cent, 2 1/2 months after treatment with mebendazole the prevalence of A. lumbricoides and T. trichiura was very low, that of N. americanus was about 20 per cent and all egg counts were very low. Prevalence rates and egg counts of A. lumbricoides returned to pretreatment levels 9 months after treatment. Prevalence of T. trichiura and N. americanus, one year after treatment, was lower than before treatment and 97 per cent of egg counts were low. Two years after treatment, prevalence of all species was normal, but mean egg counts of N. americanus were about half of pretreatment levels. Thus in areas with comparable transmission rates, annual treatment with a course of anthelmintic would keep hook-worm levels low, and an additional dose at mid year would also considerably reduce ascariasis. Presence or absence of A. lumbricoides in particular subjects varied from one examination to another, and a particular child was not more likely to have the same infection status one year later, given the prevailing infection rate. 95 per cent were positive for A. lumbricoides on one or more of three examinations held at the same time of year.