Biomedical subjects
J L Tulloch
Publications and source records attributed to J L Tulloch.
The epidemiology of malaria in a population surrounding Madang, Papua New Guinea.
Malaria is prevalent throughout coastal and lowland Papua New Guinea. Recent changes, including a shift from predominance of Plasmodium vivax to Plasmodium falciparum, appearance of chloroquine-resistant P. falciparum and decreased effectiveness of vector control programs have been observed. Epidemiological features of malaria were studied through four six-month surveys of a population of 16,500 in Madang Province from 1981-1983. Baseline data on parasitology, splenic enlargement, serology, hemoglobin levels, prevalence of 4-aminoquinolines, utilization of mosquito nets and incidence of fever were collected for use in future evaluation of malaria control measures including possible field trials of an antimalarial vaccine. Prevalence of parasitemia (all species, all ages) varied from 35.0% to 42.7% over the four surveys each of which covered a random sample of 25% of the population. The ratio of parasite species was: P. falciparum 70:P. vivax 25:P. malariae 5 in the dry seasons, shifting slightly in favor of P. falciparum during the wet seasons. Intense year-round transmission was indicated by decreasing parasite prevalence and splenic enlargement with age, low density asymptomatic parasitemias and high prevalence of antimalarial antibodies (i.e., greater than 80% of the population over five years of age was ELISA-positive). Levels of endemicity varied geographically, presence of 4-aminoquinolines in urine samples was relatively common (12.7% positive) and chloroquine resistance was widespread (81.6% in vitro, 46.6% in vivo).
Analysis of patterns of growth inhibition of P. falciparum in synchronised cultures induced by serum from children and adults from Madang, Papua New Guinea.
In this study we have modified a micro Plasmodium falciparum in vitro growth inhibition assay to allow dissection of growth inhibition induced by test sera into two categories: inhibition of intracellular schizont growth and inhibition of uptake of merozoites into a second cohort of erythrocytes. This was achieved using morphology-controlled synchronised cultures with incubation times restricted to cover either ring to schizont development or schizont to ring development. Sera tested were obtained from a large prospective study of healthy residents of Madang, Papua New Guinea, who were carefully documented with respect to presence of malarial parasites in the blood, spleen size, age, sex and history of fever. In the ring to schizont assay sera from all the children tested inhibited parasitic growth by at least 20%, compared to only 10 of 39 adults tested (P less than 0.0005). In the schizont to ring assay 20 of 39 adult sera tested inhibited the uptake of 14C-isoleucine into P. falciparum protein compared to 3 of the 15 children's sera tested (P less than 0.01). These results are interpreted as reflecting a switch from non-specific mechanisms of resistance with increasing age.
A computer simulation of the EPI survey strategy.
A Monte Carlo simulation study was designed to evaluate the sample survey technique currently used by the Expanded Programme on Immunization (EPI) of the World Health Organization. Of particular interest was how the EPI strategy compared to a more traditional sampling strategy with respect to bias and variability of estimates. It was also of interest to investigate whether the estimates of population vaccination coverage were accurate to within 10 percentage points of the actual levels. It was found that within particular clusters, the EPI method was particularly sensitive to pocketing of vaccinated individuals, but the more traditional method gave more accurate and less variable results under a variety of conditions. However, the stated goal of the EPI, of being able to produce population estimates accurate to within 10 percentage points of the true levels in the population, was satisfied in the artificially created populations studied.
The role of voluntary village aides in the control of malaria by presumptive treatment of fever. 1. Selection, training and practice.
As part of a multi-disciplinary malaria research programme in a rural area of Madang Province, the Papua New Guinea Institute of Medical Research (PNG IMR) in 1982 established a village-based intervention programme of presumptive treatment of fever in 35 villages (population about 5,200). Seventy-four villages aides, selected by people from their own village, attended two-week training courses conducted by PNG IMR staff, and were trained to dispense three-day courses of amodiaquine (for children) or chloroquine (for adults) to anyone presenting with fever (presumptive malaria). The majority of village aides, who were voluntary workers, were married men and women between the ages of 20 and 35 years, who had had up to six years' schooling. In 1983, 5,075 fever cases were treated by village aides, which represents a quarter of the number of fever episodes estimated to occur each year in this area. Utilization of village-aide services was variable, the most important determining factors being the personality and standing of the village aide, and the distance (walking time) to the village aide's house from the patient's house. The village aides' role was expanded to include taking blood slides, dispensing other medicines (aspirin and dressings), treatment of diarrhoea by oral rehydration, and registration of vital demographic events in the village. Regular supervision, currently undertaken on a two-weekly basis by PNG IMR staff, regular refresher courses, and, probably, some sort of compensation (not necessarily monetary) are important for the long-term continuation of the programme, which may serve as a model for other areas.(ABSTRACT TRUNCATED AT 250 WORDS)
The role of voluntary village aides in the control of malaria by presumptive treatment of fever. 2. Impact on village health.
A village-based programme of presumptive treatment of fever, using voluntary village aides to dispense oral chloroquine or amodiaquine, was established in 1982 by the Papua New Guinea Institute of Medical Research (PNG IMR) in 35 rural villages or hamlets near Madang, on the north coast of PNG. In the course of the following two years, village aides became an established health resource in many of those villages, although in others they were poorly utilized. In attempting to evaluate the impact of the programme on village health, a number of parameters were investigated. These included malaria-related mortality and morbidity, and the prevalence of parasitaemia and splenic enlargement in children in the study area. Deaths attributable to malaria, which accounted for 11% of deaths in the under-10 year age-group, and cerebral malaria cases were too few to be useful as parameters to evaluate the programme. No reduction in spleen or parasite rates occurred in children as a result of the village aide programme. In two villages, there was an unexplained increase in spleen rate following the introduction of a village aide. A study of malaria-related morbidity, by investigation of all fever cases occurring in a two-week recall period, was conducted in mid-1984. House-to-house interviews were carried out in 19 villages: 9 control villages, where there was no village aide, 6 where the village aide was well utilized, and 4 where the village aide was poorly utilized. The study showed that village aides had a measurable impact on morbidity due to fever in villages where they were well utilized, primarily by reducing the duration of fever through early treatment. The results also suggested that children benefitted even in the villages where the overall utilization of village aides was low. It is felt that such a programme would have had an even greater impact in areas where access to existing health services is more difficult than in the study area.
Smallpox surveillance in Bangladesh: II - Smallpox facial scar survey assessment of surveillance effectiveness.
A smallpox facial scar survey of 465 892 persons aged 0-19 years was carried out in Bangladesh in 1976, covering approximately 1% of the 0-19 year old population. Of the 4 306 persons found with facial scarring consistent with previous smallpox infection, none had a history of smallpox with onset after the last reported case on October 16, 1975. Histories taken from persons with facial scars allowed smallpox incidence to be estimated for each year from 1972 to 1975. These estimates indicate that completeness of reporting increased steadily from 11.8% in 1972 to 83.0% in 1975, reflecting the increasing effectiveness of surveillance.
The last 50 years of smallpox in Africa.
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