Biomedical subjects
Publications and source records attributed to T Harinasuta.
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An ultrastructural study was undertaken of the spleen of 13 year-old-boy who died of falciparum malaria. The spleen revealed the following: both parasitized and non-parasitized erythrocytes are phagocytosed in large numbers by macrophages, littoral and reticular cells. Blood congestion and trapping of parasitized erythrocytes are commonly seen in splenic sinusoids and cords. Erythrocytes forming rosette structure around immuno-presenting cells is observed. The results of this study provide evidence that the mechanisms underlying splenic host defence in malaria include both immunological and non-immunological interaction with erythrocytes. Splenic trapping of parasitized erythrocytes is an important defence mechanism and the phagocytosis of erythrocytes probably accounts for anaemia.
A case of subcutaneous phycomycosis involving the right thigh for 1 year duration which mimic elephantiasis was reported in a 21-year-old military man. An initial diagnosis was that of a subcutaneous tissue lesion attributed to parasitic manifestation but turned out to be that of subcutaneous fungal infection both clinically and histologically. The lesion was successfully treated with cotrimoxazole for a period of one month, and followed up for 4 1/2 months with complete cure.
Fifteen isolates of P. falciparum sporozoites obtained from patients with acute falciparum malaria from various malaria endemic areas in Thailand were tested for the presence of a common antigenic determinant in their CS protein molecules. SDS-PAGE and Western blot analysis using MAB or human serum antibodies specific to the CS proteins of the parasites revealed a common epitope shared in the CS proteins of all strains of P. falciparum tested. However, the CS proteins exhibited M.W. variation when different strains of the parasites were compared. A similar result was obtained when the human serum antibodies were used. The present study clearly indicated the occurrence of the common epitope in phenotypically different CS proteins among isolates of P. falciparum sporozoites and supported the notion that antigens containing these repetitive epitopes could be used as the candidates for the sporozoite vaccine against P. falciparum infection.
A clinical field trial of praziquantel was carried out in Nong Ranya Village, Amphoe Ban Phai, Khon Kaen Province, with a population of 309 individuals, and 94% prevalence rate of opisthorchiasis. A mass treatment was carried out using a single dose of praziquantel at 40 mg per kg body weight. Acceptance for treatment was 91%. Follow-up stool examinations performed on days 14 and 60 gave prevalence rates of 20.5% and 22.2% respectively. Side effects including dizziness, headache, abdominal discomfort, nausea, vomiting, diarrhoea, lassitude, arthralgia, sleepiness, cramps and hot sensation were the complaints from 80% of adults and 40% of children. All of these were mild and transient except in one adult female who had severe diarrhoea and required intravenous fluid infusion.
Two randomised double-blind trials were conducted to examine the activity and tolerability of mefloquine alone and in combination with sulfadoxine/pyrimethamine (MSP). In one trial mefloquine was compared with chloroquine in 40 patients with Plasmodium vivax malaria and in the other one mefloquine was compared with MSP in 40 patients with P falciparum malaria. The former trial showed that both a single oral dose of 250 mg mefloquine and a single oral dose of 450 mg chloroquine (base) were highly effective in relieving symptoms of malaria and in clearing P vivax parasitaemia. No side-effects and no changes in laboratory variables attributable to the test drugs were observed. The other trial showed that a single oral dose of 750 mg mefloquine and a single oral dose of MSP (750 mg mefloquine plus 3 tablets of 'Fansidar', were equally effective in the treatment of falciparum malaria. 2/4 treatment failures in the mefloquine group and 2/3 treatment failures in the MSP group were due to low plasma drug levels resulting from vomiting soon after ingestion of the tablets. Gametocytes of P falciparum were unaffected by either mefloquine or MSP. 5 patients in each group had side-effects such as vomiting, skin rash, diarrhoea, and transient mental confusion. Mefloquine was well tolerated by patients with glucose-6-phosphate dehydrogenase deficiency or heterozygous haemoglobin E.
Sera from 10 individuals who lived in a malaria endemic area, 10 patients with acute uncomplicated falciparum malaria and 10 patients with cerebral malaria and hyperimmune mouse serum were tested for their reactivities against Plasmodium falciparum sporozoite antigens by Western blot analysis using 125I-labeled staphylococcal protein A as the detecting reagent. These sera were shown by indirect immunofluorescence and/or circumsporozoite precipitation test to have antibodies reacting against the parasites. It was found that all serum antibodies from the three groups of individuals and the mouse serum reacted in a similar pattern with circumsporozoite (CS) proteins of P. falciparum. Ten sera from normal individuals were negative in all reactions. Monoclonal antibody (MAB) specific against CS proteins of the parasites showed that the proteins exhibited as four different molecular weight (MW) polypeptides, i.e., 67,000, 65,000, 60,000, and 58,000 daltons. These CS proteins of P. falciparum were found to be species and stage specific. Radioimmunoprecipitation using 35S-methionine-labeled parasites and sera of individuals from the various categories or MABs gave a similar result. Another protein antigen of P. falciparum sporozoites had a MW of 80,000 daltons. This antigen was not species specific, probably not membrane associated and was present in a minute quantity in the parasite's extract.
Ultrastructure of erythrocytes infected with Plasmodium falciparum in human brain, obtained 3 hours post mortem revealed gross distortion of host red cells with abnormality of the red cell surface. The superficial alterations of the parasitized cells as knob-like protrusion appear to be the sites of attachment to vascular endothelium. There was evidence of platelets sticking to the injured endothelium. The endothelial vesicular membrane is in close adhesion to the parasitized red cell, and also to the platelets involved in this mechanism. Thus, explaining the sequestration of parasitized red cell and obstruction in cerebral microcirculation, cerebral oedema and low peripheral platelet count. The was no evidence of inflammation, fibrin or thrombus formation observed in our studies.
Ninety-six patients who had heavy Opisthorchis viverrini infection were studied. Egg count per gram of faeces ranged from 10,800 to 139,000 (mean 26,044.3). Praziquantel 50 mg per kg body weight was given after a morning meal. 68 patients completed the follow up period of 60 days. The cure rate was 97.0%. The side-effects occurred in 61 patients (89.7%). The common side effects were diarrhoea, dizziness, sleepiness, epigastric pain, headache, nausea and anorexia. These side-effects were mild and transient. 62 patients (91.2%) showed clinical improvement, and 20 patients were symptom free on day 60.
Thirty-six patients with uncomplicated amoebic liver abscess were treated with low dose tinidazole 1.2 g to 1.5 g in a single or divided doses, and aspiration of the abscess. No drug related toxicity was noted. All patients responded well and there was no relapse or treatment failure.
An ELISA for immunodiagnosis of human gnathostomiasis using a crude water extract of third-stage larvae of G. spinigerum as antigen, and alkaline phosphatase labelled goat antihuman IgG in the indicator system was developed and evaluated. At the titre of 1:400 and above positive results were observed in 100% of 4 parasitological confirmed and 10 eosinophilic meningo-encephalitis (EME) typical of gnathostomiasis cases, 56% of 160 cutaneous migratory swelling cases, 33% of 24 cases with EME typical of A. cantonensis infections, 23% of 92 cases with other parasitic infections and 1.5% of blood donors. The overall sensitivity was 59% and specificity 84%. The predictive value was 77%. The results indicated that ELISA is potentially useful for immunodiagnosis of gnathostomiasis but improvement of sensitivity and specificity is needed.
Clinical features of severe opisthorchiasis were studied in 88 patients. The ratio of males to females was 6.3 : 1; 75% were over 40 years old. The presenting symptoms were obstructive jaundice, 25% associated with secondary infection of biliary system; cholangitis and cholecystitis; intraabdominal mass, which was enlarged liver; 18% had palpable gallbladder; 18% had adenocarcinoma of the bile duct. High bilirubin was found in 46% of cases, high alkaline phosphatase in 80%; elevation of serum transaminase in 78% and low serum albumin in 62% of patients. There was no correlation between severity of the disease and the faecal egg output. The obstructive jaundice patients had low or no egg output. Two patients had no eggs in stool, but numerous Opisthorchis viverrini eggs and flukes were found in the gallbladder and bile ducts at operation.
The first finding of Episthmium sp. in man is reported. Characteristics of the worm are given in detail. The infestation is an accidental one acquired from consuming raw fish, which serves as an intermediate host of Opisthorchis viverrini. The pathogenic role of Episthmium sp. in man needs further investigations.
A total of 52 adult patients with opisthorchiasis with or without concomitant intestinal helminthic infections were treated with albendazole at dosage regimens of 400 mg twice daily for 3 days (group I with 25 patients) and 7 days (group II 27 patients). By concentration method with four examinations from two faecal specimens of each patient the cure rates and percentage egg reduction on day 30 in group I and group II were 12% and 33%, 94 and 95 respectively; by Stoll method the cure rates and percentage egg reduction were 40% and 63%, 92 and 92 in group I and group II, respectively. There were no statistically significant differences between the results of the two regimens. Twenty six patients with hookworm and 9 patients with S. stercolaris infections were cured. Opisthorchis viverrini, N. americanus, A. duodenale, A. ceylanicum, E. malayanum, E. ilocanum, S. stercolaris, E. vermicularis, and T. saginata segments were expelled in stools, mostly on days 1 to 4. Most of the patients felt relieved from symptoms of pain in the right hypochondrium and epigastrium. The side effects were mild and transient. There were no evidence of toxic effects on the bone marrow, heart, liver or kidneys. Albendazole was shown to be effective against Opisthorchis viverrini infection as well as other concomitant intestinal helminthic infections; but the optimal dosage and duration of treatment have not yet been achieved.
In vitro and in vivo experiments were employed in the screening of potential anthelmintic agents against Opisthorchis viverrini infection in hamsters. A few selected groups of compounds tested included those that are commercially available as well as those that are still being tested by various pharmaceutical firms. The compounds tested in the present study were praziquantel, amoscanate, albendazole, flubendazole, metrifonate, metronidazole and benzodiazepine derivatives. Results from both in vitro and in vivo experiments showed that at the dosages employed, praziquantel was the only one that gave complete cure, as judged from faecal egg examination and worm recovery at the time of sacrifice. It was therapeutically effective against different developmental stages of O. viverrini including the metacercariae. Moreover, the drug was also effective as a chemoprophylactic agent when given 6 to 12 hr prior to being exposed to infective metacercariae. Other compounds tested were considerably less active although some might have permanently damaged the fluke reproductive capacity, while others were able to suppress egg-laying capacity only temporarily. Together, results suggests that the ineffectiveness of most agents tested in this study is not related to their inability to attain concentrations high enough to kill or damage the flukes in the biliary system but is most likely due the inherent lack of capacity to kill the flukes.
Opisthorchis viverrini has been found to be the only species of liver fluke in Thailand. The morphology is similar to that of O. felineus, but it has more deeply lobated testes, situated near the ovary. The appearance and distribution of the vitellaria with few granular clumps and the shorter and wider egg closely resemble that of C. sinensis. The adult worms live in the biliary system. Eggs pass out in faeces. On reaching water the eggs are eaten by snails, the first intermediate host. In the snail the miracidia hatch and develop further through the stages of sporocysts, rediae and cercariae in six to eight weeks. The cercariae then leave the snail, penetrate into susceptible fresh water fish, encyst in the muscle and develop into metacercariae, and infective stage, in six weeks. When ingested by man or animal the metacercariae excyst in the duodenum or jejunum and then migrate to the bile duct. They become mature within four weeks and begin to produce eggs. The life span of the fluke is over 10 years. The snail intermediate hosts are Bithynia goniomphalus, B. funiculata and B. siamensis. Many species of cyprinoid fish serve as second intermediate host; Cyclocheilichthys siaja is the most important. Cats, dogs and many fish eating mammals are definitive hosts. Man and animals acquire infection by eating raw fish containing metacercariae cysts. In Northeast Thailand "Koi-Pla" is the most popular raw fish dish. In 1980-1981 the prevalence in the north, northeast, centre and south of Thailand was 5.59, 34.60, 6.34, and 0.01%, respectively, with an overall prevalence of 14% or 7 million people.
The pathological changes are more or less related to the intensity and the duration of the infection, and are commonly seen in older patients with a large number of flukes. The pathogenesis is due to the mechanical irritation by the flukes and some toxic substances produced by them. Lesions are mainly confined to the biliary system. There is hyperplasia of the epithelial cells lining the bile ducts. In heavy and severe infections there are obstruction of the biliary tract, bile retention, extensive hyperplasia of the biliary system, with glandular proliferation of papillomatous and adenomatous type, cholangitis, periductal infiltration with eosinophils, round cells and fibrosis in the portal areas, necrosis and atrophy of hepatic cells. The bile ducts are dilated and in late cases saccular or cystic formations may develop into large cysts. The gallbladder may enlarge and contain white bile. The liver profile is generally normal. The majority of cases are symptomless. Clinical features vary from mild to severe. The symptoms and signs are vague gastro-intestinal symptoms, flatulence, anorexia, lassitude, weight loss, dull pain at the right hypochondrium, hot cutaneous sensation of the abdomen, and enlargement of the liver with some tenderness. In few cases the manifestations are severe. There is relapsing cholangitis, the patient is seriously ill and may succumb to septic shock. Cholangiocarcinoma, gallstones and obstructive jaundice are not unusual associations.