Diarrhoea and growth faltering in rural Zimbabwe.

OBJECTIVE: To assess the evidence that diarrhoea is an important cause of growth faltering in young children in developing countries. DESIGN: Prospective, longitudinal cohort study. SETTING: Worker's compounds on commercial farms in Shamva, rural Zimbabwe. SUBJECTS: 204 children < 12 months old were enrolled, 73 from birth. The median age at enrolment was 4 months. Eleven children died and 39 were lost to follow-up. INTERVENTIONS: Prospective weekly diarrhoea surveillance by farm health workers and monthly anthropometry. RESULTS: Growth faltering was severe, but there was little difference in average rates of growth between children with frequent diarrhoea and infrequent diarrhoea. The results of an interval-based data analysis were consistent with there being only a transient effect of diarrhoea on weight gain. Estimation of weight faltering following episodes of diarrhoea and the rate of return to the trend in the 9-14 month age range, indicated that weight loss associated with each episode was small (approximately 2%) and return to the child's trend was 90% complete within a month. At older ages than this, weight loss appeared to be less, and estimates were not statistically significant. CONCLUSIONS: These observations lend weight to the hypothesis that recurrent episodes of diarrhoea are not a potent cause of growth faltering in early childhood except in a small minority of largely catastrophic cases. Inadequate food intake is a more plausible explanation.

PIP: In Zimbabwe, health workers collected data on diarrhea incidence every week and anthropometric data once a month from 204 children aged less than 12 months to examine the association between diarrhea and growth faltering. 73 children were enrolled at birth. 148 children were followed throughout the entire study. 11 children died (8 because of diarrhea or protein-energy malnutrition). 39 children were lost to follow-up. The children's parents were farm laborers who lived on large-scale commercial farms in Shamva district. Diarrhea incidence peaked between 13 and 18 months. In 91% of attacks, the diarrhea was watery rather than bloody. 31 children had more than 9 diarrhea episodes (high diarrhea frequency). 25 had no more than 4 diarrhea episodes (low diarrhea frequency). There was little difference in the children's mean weight and mean length from 1 to 30 months of age between high and low diarrhea frequency subjects. The average loss of overall growth per diarrhea episode in the age range 9-23 months was 51 g and 0.18 cm. In the age range of 9-14 months, weight loss after the diarrhea episode was 2.3% of body weight, and 90% of the sudden weight decline below the child's trend was recovered in 30 days. Weight loss was less than 2.3% among older children. A 2.3% weight loss in an 8 kg child is 180 g. Assuming that diarrhea is responsible for the entire weight loss (about 66 g/episode), the reduction in overall growth is about 120 g (1.5%). The total energy needed to accumulate 120 g is 480 kcal; thus, a child would require an additional 2-3 kcal/kg/day (a small amount) to gain 120 g. These findings support the hypothesis that recurrent diarrhea episodes do not induce growth faltering except in a few cases. Inadequate food intake is a more plausible explanation.

Migrant workers and schistosomiasis in the Gezira, Sudan.

A cross sectional study of schistosomiasis in migrant laboureres in the Sudan Gezira is described. The people examined were of two ethnic groups: (i) those of local Arabic origin and (ii) those from Western Sudan, West Africa or west of longitude 27 degrees E. These two migrant groups were examined in one area treated with molluscicide and in another that was not. Almost all the schistosome infections were with Schistosoma mansoni, with a prevalence of 57% over-all and up to 89% in particular groups. The prevalence was lower in the treated than in the untreated area, and slightly lower in the Arab nomads than in the others, except that it was markedly lower in females from the West in the treated area. These results are consistent with the known water-contact habits of the two migrant groups. An association was observed between infection and liver and spleen enlargement, but not between infection and other symptoms. The potential importance of migrants in transmitting the infection is discussed.

Comparative xenodiagnosis with three triatomine species of different hosts with natural and experimental chronic infections with Trypanosoma (Schizotrypanum) cruzi.

Simultaneous xenodiagnosis was made of 29 patients with chronic Chagas's disease, six naturally infected opossums (Didelphis azarae) and of a Rhesus monkey with an experimental chronic infection with Trypanosoma (Schizotrypanum) cruzi (Peru strain). Patients and opossums were from an endemic area in the state of Bahia, Brazil, where Panstrongylus megistus is the sole domiciliary vector of the disease to man. Various instars of P. megistus Triatoma infestans and Rhodnius prolixus were used. The proportion of bugs infected with compared with bloodmeal intake by a computer programme using linear logistic analysis. The analysis showed that there are intrinsic interspecific differences in susceptibility to infection with Trypanosoma cruzi between the three triatomine species used and that subsequent infection of bugs with T. cruzi is correlated with the quantity of blood ingested. The results show that interspecific differences of bloodmeal size and intrinsic differences in susceptibility to T. cruzi between triatomine species are limiting factors for the standardization and interpretation of the results of xenodiagnosis.

Effects of suramin on ocular onchocerciasis.

39 patients (Group A) with ocular onchocerciasis in the Sudan-savanna of north Cameroon were given 4-6 g of suramin and followed in detail over 1-2 years. 39 other patients (Group B) received suramin followed 2 weeks later by a 6-7 day course of diethylcarbamazine (DEC). A further 18 patients (Group C) received placebo injections and were followed in the same way by the same observers. Suramin caused serious general reactions among the 100 patients who started the course - 1 case of stomatitis, 1 exfoliative dermatitis, and several cases of severe prostration, among which 2 ended fatally. These reactions underline the urgency for further studies on the toxicity of suramin, which is without doubt an efficient macro- and micro-filaricidal drug. Changes which occurred in the ocular lesions are described in detail. There was an initial aggravation of punctate and sclerosing keratitis, and sometimes a serious aggravation or development of anterior uveitis, corresponding to the peak microfilaricidal effect of the drug. The possibility of a simultaneous adverse effect on the optic disc is discussed. Despite these reactions, which might have been avoided by prior elimination of microfilariae by DEC, the eyes were in general quieter at 3 months and thereafter than before treatment. However, no posterior segment lesion improved after suramin, and the majority remained unchanged. The findings at the end of the trial were as follows: No. of lesions (see article).

Effects of diethylcarbamazine on ocular onchocerciasis.

A single 10-14 day course of diethylcarbamazine (DEC) was given under betamethazone cover to 18 patients (Group A) with ocular onchocerciasis, and the effects were studied in detail over 1-2 years. A comparison was made with the findings in 21 patients (Group B) who received a similar course to be followed by a weekly suppressive 100-200 mg dose of DEC. A further 18 patients (Group C) served as controls. The initial DEC course provoked severe general reactions, but ocular complications could be controlled by betamethazone. The weekly suppressive dose was not acceptable to the majority of patients, and only one young patient with severe iritis who improved during the initial course took the weekly tablet voluntarily over 2 years. The initial DEC course reduced the numbers of microfilariae in the eye and was of temporary benefit to lesions of the anterior segment, but it did not affect lesions of the posterior segment. A possible adverse effect on the optic disc is discussed. Any beneficial long term effect was almost confined to Group B, and to lesions of the anterior segment. The best to hope for in lesions of the posterior segment was arrest of further development. The findings at the end of the trial were as follows: No. of lesions (see article).

The head nodule and ocular onchocerciasis in Africa.

In a population survey in 1970/72 the prevalence of head nodules was found to be 1.7% in 1098 cases of onchocerciasis in the rain-forest and 0.6% in 1128 cases in the Sudan-savanna of Cameroon. In a follow-up survey in the same villages 3-4 years later more attention was given to the detection of head nocules, and the corresponding prevalences were 5.5 and 5.0%. In the follow-up survey a strong associated was demonstrated between the presence of head nodules and lesions of both the anterior and posterior segments of the eye. The relative risks of having eye lesions in patients with head nodules compared with those without were 2.9 and 7.5 in the rain-forest and savanna respectively. In a group of 483 clinic cases with ocular onchocerciasis from the savanna palpable head nodules were detected in 23.6%, and in a further 140 selected cases from the same area with posterior segment eye lesions, head nodules were detected in 31.4%. Confirmation of the onchocercal origin of the nodules was obtained in doubtful cases by biopsy. Many head nodules probably remain undetected in onchocerciasis surveys. They are often very small, flat, and hard, and tightly adherent to the under-lying periosteum, and the patient will often point out the presence of a nodule even when none has been detected after careful examination. The presence of a head nodule has long been one of the recognized "risk factors" associated with a high prevalence of blindness in Central America, but there have been no detailed studied in African onchocerciasis. A trial is in progress to assess the effect of nodulectomy on the development of ocular lesions.

Seasonal variation in the concentration of Onchocerca volvulus microfilariae in the skin?

Repeated multiple skin snips in 18 persons with onchocerciasis from the Sudan-savanna of West Africa suggested the possibility of a seasonal variation in microfilarial concentrations. This variation may be an evolutionary adaptation of the parasite to the climate conditions that affect the seasonal distribution of the vector, but a migration of the microfilariae in the skin layers caused by the Simulium bites cannot be excluded.