Application of Radioisotopes in the Study of Hookworm Infection in Thailand*

Abstract

Summary Anaemia caused by hookworm is common in Thailand and it is known that such anaemia is due to iron deficiency resulting from intestinal blood loss. In the present experiments, blood loss, iron absorption, iron reabsorption and serum albumin loss were studied using radioactive 51Cr and 59Fe in 15 patients with hookworm anaemia. Blood loss per worm per day was found to be 0–097 ml (range 0–023‐0‐260) and it was inversely proportional to the total amount of hookworms. About 64% (range 41–83%) of the iron loss caused by hookworm was reabsorbed in the intestine in 6 patients studied. There was a linear relationship between iron reabsorbed and iron loss, and the state of iron deficiency. An average of 89% of iron given orally was found to be absorbed in 9 hookworms patients with severe anaemia. 51Cr‐labelled human serum albumin was used to study the loss of plasma protein in 15 hookworm patients. The results showed that they lost albumin equivalent to that in 21 to 128 ml of plasma per day or 0–06 to 2–74% of the intravenously administered. 51Cr‐albumin appeared in the subsequent 4 days faecal collection from patients harbouring 1,200 to 20,000 hookworm egg/gm faeces. There was a direct relationship between the number of egg/gm of faeces and the faecal 51Cr‐albumin excretion and an inverse correlation between the serum albumin concentration and the amount of 51Cr‐albumin measured in the stool. The urinary excretion test for 58Co‐labelled vitamin B12 and 3H‐labelled folic acid were also performed in 27 hookworm patients. Five out of 21 and 6 out of 13 cases showed possibly impaired absorption of vitamin B12 and folic acid respectively. The serum vitamin B12 concentration in 27 hookworm patients were also lower than in normal subjects. All these findings showed no relationship to the degree of anaemia or the number of worms recovered from the hookworm patients.

Pathways to the impairment of human nutritional status by gastrointestinal pathogens

“…It is in the domain of nutrient wastage from already accumulated body reserves that A. duodenale and N. americanus are important in their negative nutritional impact on the human hosts. Protein losing-enteropathy has been confirmed in hookworm infected individuals, but only in heavily infected subjects (Darke, 1959;Areekul et al 1971Areekul et al , 1972. Mild burdens of worms did not increase the faecal losses of nitrogen (Variyam & Banwell, 1982).…”

Haemostatic defect in non-immune patients with falciparum malaria: no evidence of diffuse intravascular coagulation.

“…0-12 Furthermore, whereas some workers advocate the use of heparin in such cases, 4 51314 others do not.10 [15][16][17][18] The past few years have seen an increasing number of nonimmune patients who do not or only irregularly take prophylactic antimalarial drugs. Thus the disease may be imported in nearly all parts of the world.…”

Hookworm Disease: Nutritional Implications

“…Crowding of worms is found to reduce blood loss per worm; in dogs the blood loss per worm is greater in mild infections with A. caninum and A. braziliense than in severe infections [20,21]. This pattern noted in some studies of humans as well [22,23]. Since crowding also results in reduced egg output per worm [24], it is likely that the blood loss expressed on the basis of egg output per g of feces would remain steady.…”

“…However, there are methodologic problems in studies with radioiodinated proteins [36]. Using slCr-labeled albumin, Gupta et al [34] found that protein loss in patients with mild infection «1,340 eggs per g of feces) was not greater than that in controls [34], whereas Areekul et al [23,35] showed that there was increased intestinal protein loss that correlated with the worm load. Gilles et al [30] and Areekul et al [35] showed that the protein loss exceeded that from blood loss alone, but the truth of this observation has not been adequately determined with the use of multiple, simultaneously labeled plasma proteins.…”

“…While the worms feed in the intestine, variable amounts of plasma and extracellular fluid along with erythrocytes may be lost into the intestinal lumen [11,12]. Loss of protein into the intestine has been studied by the measurement of fecal nitrogen excretion [31,32] and by the use of proteins labelled with 131 1 [30,33] and slCr [23,34,35]. While the fecal nitrogen excretion was not markedly different between patients with mild infection «200 worms) and those with no infection [31], fecal nitrogen excretion was increased in patients with heavy infection [32].…”