The American Journal of Tropical Medicine and Hygiene - Volume 26, Issue 6, November 1977

In an area of El Salvador moderately endemic for malaria, use of the indirect fluorescent antibody test (IFA) showed that 44% of the infants born to mothers who had IFA responses to Plasmodium vivax of 1:20 or higher during the latter part of their pregnancy had positive IFA responses of 1:10 or higher to this antigen. No serum from an infant was positive in the absence of some level of malarial response in the mother.

A chemosuppressive field trial in an area of Thailand with known chloroquineresistant falciparum malaria was undertaken to test the efficacy of the preparation sulfadoxine (S)-pyrimethamine (Py) in suppressing falciparum and vivax parasitemias. Seven hundred and forty-seven Thai villagers were randomly assigned to one of five study groups: sulfadoxine (1,000 mg)-pyrimethamine (50 mg) every 2 weeks [S-Py (high dose)]; sulfadoxine (500 mg)-pyrimethamine (25 mg) every 2 weeks [S-Py (low dose)]; diformyldapsone (400 mg)-pyrimethamine (25 mg) weekly [DFD-Py (high dose)]; diformyldapsone (200 mg)-pyrimethamine (12.5 mg) weekly [DFD-Py (low dose)]; and placebo. Six hundred and eight-eight study subjects (92%) completed the 26-week trial. Sulfadoxine (1,000 mg)-pyrimethamine (50 mg) given every 2 weeks was shown to be an effective chemosuppressive against both falciparum and vivax parasitemias, causing an eight-fold reduction in falciparum parasitemias, and an approximately three-fold reduction in vivax parasitemias. While the low dose S-Py group and the two DFD-Py groups were less effective than the high dose S-Py group in suppressing falciparum parasitemias, the high dose DFD-Py combination was as effective as the high dose S-Py combination in suppressing vivax parasitemias. There was no evidence of drug reactions. A discernible decrease in the leukocyte count was noted over a 6-month period in the high dose S-Py group.

A series of studies on rhesus monkeys infected with sporozoites of the M and B strains of Plasmodium cynomolgi have shown: 1) at the same total course doses (with quinine as a companion blood schizonticidal drug) 7-day and 14-day dosage regimens of pamaquine, pentaquine, or isopentaquine are essentially equally effective in producing radical cure of infections with the M strain; 2) at the same total course dose (with chloroquine as a companion drug) a 7-day dosage regimen of primaquine is at least as effective as a 14-day dosage regimen in inducing radical cure of infections with the B strain, and may be slightly more effective; 3) at the same total course doses (with chloroquine as a companion drug), single dose, 3-day, and 7-day dosage regimens of primaquine or 4-methyl primaquine are essentially equally effective in producing radical cure of infections with the B strain. These observations have led to the conclusion that the total dose of 8-aminoquinoline administered is the primary determinant of radical curative activity, rather than the duration of drug treatment. This total dose concept derives support from currently available observations on the capacity of primaquine to cure naturally acquired and induced infections with P. vivax and underpins the current search for 8-aminoquinoline derivatives which will cure such infections when administered in single dose or three daily dose treatment regimens.

Serum and cerebrospinal fluid (CSF) IgM were measured in 182 patients at various stages of Gambian sleeping sickness and correlated with antibody levels measured by enzyme-linked immunosorbent assay (ELISA). Each of these tests in serum gave a 30% false negative result, but when both were used this fell to 12%. Measurements of IgM in CSF were raised in 87% of patients with advanced disease and in none of the early cases. The IgM levels fell slowly to normal by 12 months after treatment. A high level at this time, or a rise after treatment, was helpful in diagnosing relapsed patients. Antibody levels in CSF were of no use in diagnosis or prognosis, and were raised in many controls.

Sera from 16 patients suffering from oral, nasal, oro-nasal or laryngeal types of Sudan mucosal leishmaniasis were tested against leishmanial antigen by three immunodiagnostic methods. Reactive soluble antigen was prepared from sonicated promastigotes. When tested against undiluted sera, in all 16 cases it gave easily visible precipitin lines in agar gel in both immunodiffusion and counterimmunoelectrophoresis tests. In immunofluorescence tests, with promastigote slide antigen and using the indirect antibody technique, the sera were positive at serum dilutions ranging from 1:200 to 1:6,400. There was no correlation between fluorescent titer levels and the strength of precipitin reactions in the immunodiffusion and counterimmunoelectrophoresis tests. Sixteen normal sera gave negative results in all three tests.

Immediate fixation of stool specimens in polyvinyl alcohol fixative (PVA) was compared with Schaudinn's fixation delayed until the specimens were received in the laboratory, in a series of 100 consecutive positive stool specimens. More specimens were found positive following PVA fixation, and the numbers of organisms present on the slides were greater in specimens processed by this technique than after Schaudinn's fixation. It is concluded that immediate fixation results in the preservation of larger numbers of organisms in a recognizable state. The routine use of PVA fixation prior to transportation of the specimen to the laboratory is recommended.

An active worm was seen in the right eye of a 62-year-old man in Malaysia. The worm was behind the lens and attached at one end to some vitreous fibers. It was tentatively identified as an immature Dirofilaria immitis. There appear to be only five previous authentic reports of filariae in the vitreous.

In four neighborhoods of Puerto Limón, a Caribbean coastal city in a tropical rainforest area of Costa Rica, examination of 1-ml samples of night blood from 1,142 randomly selected, and 1,196 associated, persons by the Knott and filter-chamber techniques revealed microfilariae of Wuchereria bancrofti in about 3% of the 2,338 samples. The frequency of infection was higher in males (3.9%) than in females (1.9%), higher in persons of black (4.1%) than of white (1.0%) race, and highest in persons aged 10–19 (4.0%) and over 50 years (4.8%), lowest in those under 10 years (1.1%). The median microfilaria density was 3.5, the highest 45, per 20 lambdas of blood. Microfilaremia was distinctly periodic. Dissection of 663 female Culex pipiens fatigans from 42 houses of infected persons revealed filarial larvae in 25; only 1 larva was third (infective) stage. Of 64 infected persons, 11 had clinical findings suggestive of filariasis. Elephantiasis was seen in 21 others. Other forms of symptomatic filariasis without microfilaremia, though presumed to be present, were not assessed specifically.

In 75 biopsy specimens of skin from 34 patients with streptocerciasis who had been treated with diethylcarbamazine, we found 39 female and six male adult Dipetalonema streptocerca in the dermal collagen. This is the first report of adult male D. streptocerca in man, and identifying features are described.

A precipitin reaction was observed when sera of cotton rats infected either naturally or experimentally with Angiostrongylus costaricensis were tested by gel double-diffusion against sera obtained from three biopsy-confirmed human cases of A. costaricensis. With immunoelectrophoresis, the antigen was demonstrated in the serum of infected rats. The antibody in the human serum was mostly of the IgG type. No cross reactions were seen with sera from individuals infected with the common intestinal helminths, or individuals serologically positive for Toxocara, A. cantonensis, Chagas' disease, amebiasis, leishmaniasis, toxoplasmosis, or syphilis.

Sera from patients with a variety of infections were used to compare the sensitivity and specificity of the complement fixation (CF) and the indirect immunofluorescence (IIF) tests for schistosomiasis. Adult antigens were used in both tests. The sensitivities of the IIF and CF tests were 95% and 69%, respectively; the specificities were 98% and 100%, respectively. There was no statistical difference between the number of positive reactors among those individuals with no detectable helminth infection and those infected with helminths other than schistosomes. Infected people native to endemic areas had lower reactivity in both tests than did infected U.S. citizens who resided in endemic areas for only a few years. We concluded that the IIF test with adult antigen was more sensitive than and as specific as the CF test; therefore, the IIF test is the procedure of choice for routine diagnostic serology of schistosomiasis.

Immunoglobulins, anti-Schistosoma mansoni antibodies, complement components and schistosome antigens were investigated in milk from mothers infected with S. mansoni. No significant differences of immunoglobulins or complement component levels were observed between infected and control mothers. Anti-S. mansoni antibodies were detected in the milk of 8 out of 25 infected mothers. A significant relationship was observed between serum and milk antibody levels. Two circulating S. mansoni antigens, parasite “M” antigen and antigen “4,” were demonstrated in milk from infected patients by the double diffusion micromethod. The function of these immunologically active substances transmitted by milk from mother to child is discussed.

Scanning photographs of the surface of normal adult male and female Schistosoma mansoni are given. The specimens were prepared using a thiocarbohydrazide technique which facilitates the binding of osmium. The resultant deep penetration of osmium preserves surface detail for electron reflection. The schistosomal tegument is characterized by a variety of surface bosses and spines. The function of certain of these is thought to be tactile or as chemoreceptors. Numerous tegumental pores surrounding setae in surface tubercles are shown. Clefts in the inner aspect of the gynecophoral canal are also seen. The excretory pore in both male and female is shown, along with a cluster of receptors at the terminus of the gynecophoral groove. Such grouped receptors may function to indicate position of the worm in copula.

Cellular and humoral immune responses to soluble egg antigens (SEA) were studied in the course of Schistosoma mansoni infection in the hamster. No immune response to SEA could be detected before the parasite had started oviposition. The liver granuloma size reached a maximum 6 weeks after infection and decreased rapidly thereafter. The in vitro cell-mediated immune response to SEA (lymphocyte blast transformation) showed a maximum reaction 12 to 16 weeks after infection (depending on the infection rate) and also declined later. Parallel to the lowered reactivity of the lymphocytes to SEA in vitro, responsiveness to the nonspecific T-cell mitogen, phytohemagglutinin M, was also reduced in chronic infections. Humoral anti-SEA antibodies could be detected in increasing amounts up to 10 weeks after exposure.

Edwardsiella tarda was isolated during etiologic and epidemiologic investigations of diarrheal disease agents in man and for Enterobacteriaceae in various species of wild-caught animals in Panamá. A total of 50 strains were recovered from approximately 14,000 specimens cultured between 1965 and 1972. In this period, Edwardsiella was isolated from ten individuals with a clinically diagnosed diarrheal syndrome, while 20 of some 3,000 persons from rural areas were asymptomatic carriers of these organisms. Edwardsiella tarda was also associated with two fatal cases of extraintestinal infection in man. In both cases liver abscess was a predominant feature. Edwardsiella was not demonstrated in either symptomatic or asymptomatic persons from urban areas. Edwardsiella tarda was present among some of the wild fauna of Panamá; various species of animals including snakes, toads, monkeys, and opossums harbored this organism.

In the first experiment two rhesus (Macaca mulatta) and two cynomolgus (Macaca fasicularis) monkeys were inoculated intranasally (i.n.) with 3 × 107 plaque-forming units (PFU) of the Peking strain of Japanese encephalitis virus (JEV) to establish the time course of infection and resulting mortality. The onset of clinical signs for both species of monkeys occurred on days 5 to 9, with fever of several days duration, anorexia and depression. Death ensued in 11 to 12 days. An i.n. median lethal dose equivalent to 2.5 × 104 PFU of the Peking strain of JEV was determined in 16 additional cynomolgus monkeys. Clinical signs of infection, virus-neutralizing antibody formation, and mortality were dose-dependent for the doses of virus inoculated. Total peripheral blood leukocyte and neutrophil values increased midway during the course of infection in monkeys that died with encephalitis. Microscopic lesions of JE were similar in monkeys that died following virus challenge. No species-related differences in response to JEV challenge were evident. A nuclease-resistant complex of polyriboinosinic·polyribocytidylic acid, poly-l-lysine and carboxymethylcellulose [poly(ICLC)] reduced mortality by 50% in monkeys treated initially 8 or 24 h after virus challenge. Mean survival time of nonsurvivors was prolonged 3.5 days and microscopic lesions of encephalitis were less severe in the poly(ICLC)-treated monkeys when compared to infected-untreated monkeys. The response of rhesus and cynomolgus monkeys to JEV challenge by the i.n. route of inoculation thus provides a useful model for the study of potential antiviral compounds in host defense against Japanese encephalitis.

Sequential electronmicroscopic studies of Aedes albopictus mosquitoes infected with dengue-2 virus showed replication of virus particles and vesicular structures confined to cells having an active, rough, endoplasmic reticulum. Small granules not found on the surface of virions produced in mammalian cells were seen on the envelopes of the virus particles. There was no evidence of nuclear involvement as described in infected mouse neurones, and there was no apparent impairment of cellular function. Substantial viral replication was confined to cells of the salivary glands and nervous tissue, with lesser involvement of midgut, hemocytes, epidermal cells, fatbody, and foregut.

Venom from the brown recluse spider, Loxosceles reclusa, reacted with human erythrocytes to form venom-sensitized erythrocytes. These cells were agglutinated specifically by high dilutions of adsorbed rabbit antivenin or were lysed by normal blood group compatible human sera. The specific rabbit antivenin prevented venom from attaching to erythrocytes, from interacting with serum complement, and from producing dermonecrotic lesions in rabbits. Results of experiments involving heat inactivation and adsorption to erythrocytes provide circumstantial evidence to suggest that the three biological activities of venom could be associated with a single component or few components with similar properties. The component interacting with serum complement is immunologically distinct from a factor in cobra venom which possesses similar biological activities.

Examination of specimens collected after anthelmintic treatment revealed that among 50 persons infected with Trichostrongylus species in each of three regions of Iran (northern, central, and southwestern), T. lerouxi Biocca, Chabaud, and Ghadirian, 1974 was found in 22%, 14%, and 8%, respectively. The corresponding mean numbers of T. lerouxi were 5.0, 4.5, and 2.3 per infected person. These findings bring to nine the number of Trichostrongylus species reported in man in Iran.

A case of accidental oculofacial vaccinia in a 1-yr-old Thai female infant is described; it is the first such case to be reported from Thailand.