Showing papers in "American Journal of Tropical Medicine and Hygiene in 1980"

Nosocomial outbreak of viral hemorrhagic fever caused by Crimean Hemorrhagic fever-Congo virus in Pakistan, January 1976.

Abstract: This paper describes the clinical, epidemiological, and laboratory investigations undertaken to isolate and identify the etiological agent of a nosocomial cluster of hemorrhagic fever cases due to Crimean hemorrhagic fever (CHR)-Congo virus. Since this virus is usually transmitted by ticks it was surprising that the index case, in a nomadic shepherd, occurred during the winter season when ticks are relatively inactive. These are the first cases of CHF-Congo virus found in humans in Pakistan. Investigations on other biological properties, particularly strain differences and virulence, are being continued at the Islamabad laboratory.

Intermediate and transport hosts of Toxoplasma gondii in Costa Rica.

Abstract: Toxoplasma gondii was isolated from 3.5% of 202 Mus musculus, 12.5% of 120 Rattus norvegicus, 16% of 106 sparrows (Zonotrichia capensis), and from 54% of 50 chickens from Costa Rica. The infection rate in chickens increased from 23% in those weighing less than 500 g, to 73% in those between 500 and 1,000 g, indicating a rapid rate of acquiring infectin, probably from the soil in which they constantly search for food. No isolates were made from Musca domestica, or from four genera of roaches caught in the wild. However, Toxoplasma was isolated from four of 16 lots of earthworms. Most strains of Toxoplasma isolated from Costa Rican cats produced chronic latent infections in mice. However, even when infected with virulent strains, mice died at a time when numerous bradyzoites had been formed. Also, the availability of bradyzoites in chickens 8-10 days after ingestion of oocysts was comparable to that in mice. Therefore, several infected prey species are available as intermediate hosts to cats, providing the bradyzoites essential for the shedding of large numbers of oocysts. The isolation of Toxoplasma from earthworms or the soil associated with them illustrates their possible role as transport hosts to infect chickens and other birds feeding on them. The possible role of other transport hosts could not be confirmed.

Enhancement of Dengue Virus Infection in Monocytes by Flavivirus Antisera

Abstract: Enhanced dengue 2 virus (D2V) infection in suspension cultures of human peripheral blood mononuclear phagocytes (PBL) produced by subneutralizing concentrations of dengue antisera has been described previously. In this study, the enhancement phenomenon was found to be a general property of representative flavivirus antisera. All except one of 24 antisera, which had been raised by 1-3 injections of flaviviruses in rabbits, enhanced the growth of dengue 2 virus in human PBL. Flavivirus antisera showing the greatest level of cross-reactivity against a battery of 42 flavivirus antigens in the hemagglutination-inhibition test were most potent in enhancing dengue replication in PBL cultures. Cross-neutralizing reactivity did not relate to enhanced D2V infection. However nearly one-half of studied flavivirus antisera neutralized D2V at dilutions of 1:10 or 1:20. Heterotypic D2V neutralizing antibody could serve as a "brake" on infection enhancement in vivo. Observations should be made in the field to look for possible enhancement of dengue infection in heterotypic flavivirus immunes.

Quick Kato smear for field quantification of Schistosoma mansoni eggs.

Abstract: The 50-mg Kato thick smear was modified by using stainless steel templates which deliver 20 mg of stools accurately; fecal material can thus be processed in the field and the smears cleared within 15 minutes. The counts obtained from the 20-mg quick Kato were proportional to those obtained by the 50-mg thick smear.

Experimental transmission and field isolation studies implicating Culex pipiens as a vector of Rift Valley fever virus in Egypt.

Abstract: Attempts were made to isolate virus from wild caught mosquitoes during the 1977 and 1978 Rift Valley fever (RVF) epizootics in Egypt Over 95% of the 55,126 mosquitoes collected from epizootic areas in the Nile Delta and Valley were Culex pipiens Two strains of RVF virus were isolated from unengorged female C pipiens taken in 1978 Laboratory-reared C pipiens originating from a population sample from the Nile Delta epizootic area transmitted RVF virus The infection rate of mosquitoes that fed on viremic hamsters was 867%; the transmission rate was 400% (462% based only on infected mosquitoes) From these results, it is suggested that C pipiens was a vector of RVF virus during the 1977-1978 epizootics in Egypt

Characterization of Leishmania spp. by isozyme electrophoresis.

Abstract: In this study, isozyme patterns for 14 different enzymes were compared for culture strains of Leishmania braziliensis, L. hertigi, L. mexicana, L. donovani, L. tropica, and L. adleri. The isozyme separation was made by means of cellulose acetate electrophoresis. Each of the species had distinct isozyme patterns for aspartate aminotransferase, glucose 6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, and fructokinase. For other enzymes, two or more species had identically migrating bands; however, by using combinations of the other 10 enzymes it was possible to separate any one of the six species. In addition to these interspecific differences the Panama strains of L. braziliensis had two different malic dehydrogenase isozyme patterns; therefore, they fell into two distinct groups. These strains otherwise had identical isozyme patterns.

A new selective agent for eukaryotic cloning vectors.

Abstract: An aminoglycoside antibiotic, G418, has been shown to be an inhibitor of many pro- and eukaryotes at concentrations from 1-300 microgram/ml. A bacterial R-plasmid determinant that phosphorylates and inactivates antibiotic G418 can be introduced into yeast by transformation and expresses resistance to G418. It is suggested that this combination of antibiotic and dominant resistance mechanism may be useful in recombinant DNA studies as a cloning selection in eukaryotes.

Alveolar hydatid disease. A review of clinical features of 33 indigenous cases of Echinococcus multilocularis infection in Alaskan Eskimos.

Abstract: The clinical features of 33 cases of alveolar hydatid disease (AHD) in Alaskan Eskimos and a review of the surgical experience with this disease are presented. Among untreated patients, progression of the disease to a fatal outcome was observed in 70%. The primary hepatic lesion resembles cancer, and errors in diagnosis by both the surgeon and pathologist are common. Although surgical resection of the entire primary hepatic lesion offers the only proven curative treatment, only 26% of those explored were resectable. All seven patients resected for cure are alive 6-27 years post-operatively (average survival, 14.7 years). A 5-year experience with continuous mebendazole therapy in the management of five nonresectable cases of AHD indicates that a favorable effect of this drug is being observed. It now appears that Echinococcus infections are no longer the sole province of the surgeon. Although the role of medical therapy is not yet clearly defined, it must be considered in the management of all cases of AHD. The first reported locally-acquired case of AHD in the conterminous United States, and the widespread occurrence and expanding range of E. multilocularis in the north-central United States and south-central Canada, point to the increasing public health importance of alveolar hydatid disease.

A Longitudinal Study of Human Malaria in the West African Savanna in the Absence of Control Measures: Relationships between Different Plasmodium Species, in Particular P. Falciparum and P. Malariae*

Abstract: The research project on the epidemiology and control of malaria conducted in the Garki District, Kano State, jointly by the Government of Nigeria and the World Health Organization included among its objectives the study of the baseline epidemiology prior to the introduction of any control measures. The present paper analyzes the project's data with respect to the relationships among the three species of Plasmodium present, P. falciparum, P. malariae and P. ovale. Parasitemia with P. falciparum or P. malariae is more likely in the presence than in the absence of the other species. Among persons positive for P. falci- parum, those with a higher density of parasitemia are more likely to have P. malariae also than those with a lower density of P. falciparum parasitemia. There is a pronounced seasonal alternation in prevalence between P. falciparum and P. malariae. The research project on the epidemiology and control of malaria conducted in the Garki District, Kano State, jointly by the Government of Nigeria and the World Health Organization included among its objectives the study of the baseline ep- idemiology prior to the introduction of any control measures. The present paper analyzes the proj- ect's data on prevalence, incidence, and parasite density by season and age, with respect to the relationships among the three species of Plasmo- dium present, P. falciparum, P. malariae and P. ovale.

Human Babesiosis on Nantucket Island: Prevalence of Babesia microti in Ticks*

Abstract: In order to derive direct evidence implicating Ixodes dammini as a vector of human babesiosis, we determined the prevalence of Babesia microti infection in nymphal I. dammini collected on Nantucket Island. In experiments in the laboratory we found that nymphs remained attached to hamsters for about 3 days. Babesial infection was transmitted more often during 54 hours of attachment then during 36 or 48 hours. Since parasites were demonstrable in salivary glands solely after 48 hours, we derived an engorgement index for identifying ticks attached for 2 days or more. Of 156 nymphal I. dammini, collected from white-footed mice in 1979, 86 were engorged sufficiently to satisfy this index of attachment, and the salivary glands of four contained B. microti parasites. This demonstrates that about 5% of nymphal I. dammini are infected in nature. Risk of human infection can be reduced by prompt removal of attached ticks.

Brugia malayi: Relationship between Anti-Sheath Antibodies and Amicrofilaremia in Natives Living in an Endemic Area of South Kalimantan, Borneo*

Abstract: A seroepidemiological approach was taken to elucidate the relationship between anti-microfilarial antibodies and amicrofilaremia in humans living under natural conditions of exposure to Brugia malayi. Entomological observations indicated that all of the people in the study population in South Kalimantan, Borneo, were exposed repeatedly to filarial infection. A third of the population had antibodies to the sheath of microfilariae. The prevalence and titer of anti-sheath IgM was higher than anti-sheath IgG or IgA. There was a statistically significant correlation between anti-sheath antibody and amicrofilaremia and these antibodies may play a role in regulating peripheral microfilaremia.

Transovarial Transmission of Yellow Fever Virus in Stegomyia Mosquitoes

Abstract: Transovarial transmission of two strains of yellow fever virus was demonstrated in three colonized geographical strains of Aedes aegypti following infection by intrathoracic inoculation. Infected progeny were detected in F1 offspring from only the first three ovarian cycles (OVC). The overall minimum filial infection rate for the first three OVC was 1:596; rates were loser in the second and third OVC. Virus survived in eggs for longer than 4 months and was recovered from progeny of three immersions of first OVC eggs. Infected progeny averaged a longer time to pupation than noninfected siblings. Transovarial transmission of virus was also demonstrated in first OVC progeny of Aedes mascarensis.

Variation in Virulence for Mice and Rhesus Monkeys Among St. Louis Encephalitis Virus Strains of Different Origin

Abstract: The virulence characteristics of 67 strains of St. Louis encephalitis (SLE) virus isolated from various sources in North, Middle, and South America were compared in mice and rhesus monkeys. Each virus strain was titrated in mice exactly 21 days old and virulence was expressed as the ratio of intracerebral (ic)/intraperitoneal (ip) LD50. Virus strains fell into three groups: 1) high virulence (ic/ip LD50 ratio approximately 1.0); 2) intermediate virulence (variable mortality over a wide dose range); and 3) low virulence (ic/ip LD50 less than or equal to 0.00002). Virus strains isolated during Culex pipiens and Cx. nigripalpus--borne epidemics in the eastern United States were highly virulent for mice, whereas a high proportion of the endemic virus strains isolated from Cx. tarsalis in the western United States were attenuated. Virus strains isolated from birds (the usual host for SLE virus) were highly virulent, in contrast to strains from rodents and carnivores, which were attenuated. Isolates from humans exhibited variable virulence characteristics. In experimentally-infected mice, virulence correlated with high viremia, replication in extraneural tissues, and earlier neuroinvasion. Mouse virulence correlated with clinical and histopathologic markers of pathogenicity for ic inoculated rhesus monkeys. Monkeys immunized with nonpathogenic strains by subcutaneous inoculation were partially protected against ic challenge with a virulent virus strain. The virulence classification of SLE virus strains is discussed in terms of epidemiologic correlations. This classification provides a framework for future studies on the antigenic, genetic, and biochemical bases for SLE virus strain variation.

Clinical abdominal angiostrongylosis. A study of 116 children with intestinal eosinophilic granuloma caused by Angiostrongylus costaricensis.

Abstract: A total of 116 cases of intestinal eosinophilic granuloma caused by Angiostrongylus costaricensis in children were studied during the 10-year period 1966-1975 at Costa Rica's National Children's Hospital. A similar prevalence of cases was observed each year. The disease was twice as frequent in males as in females, and occurred predominantly in children 6-13 years old (53% of cases). The clinical symptoms were those of "acute abdomen," with pain at the right iliac fossa, pain on palpation, a tumor-like mass, abdominal rigidity, and painful rectal examination. The picture was, nevertheless, mild to moderate. Fever was classified as mild. Leukocytosis with predominance of eosinophils was seen in most cases. Radiology revealed rigidity and spasticity of the intestinal wall with poor filling on medium contrast. Thiabendazole and diethylcarbamazine were given, but there was no evidence that they were effective. Surgery was performed in 90 cases--appendectomy, ileo-colonic resection, or hemicolectomy. The main localizations of the lesions were the cecum, ascending colon, appendix, and small intestine. The pathologic findings in tissues were edema and rigidity of the intestinal wall, yellow granulations in the subsera and, in the later years of the study, eggs, larvae, or the parasite itself. Two of the patients died; the remainder recovered.

Yellow fever in the Gambia, 1978--1979: epidemiologic aspects with observations on the occurrence of orungo virus infections.

Abstract: An epidemic of yellow fever (YF) occurred in the Gambia between May 1978 and January 1979. Retrospective case-finding methods and active surveillance led to the identification of 271 clinically suspected cases. A confirmatory or presumptive laboratory diagnosis was established in 94 cases. The earliest serologically documented case occurred in June 1978, at the extreme east of the Gambia. Small numbers of cases occurred in August and September. The epidemic peaked in October, and cases continued to occur at a diminishing rate through January, when a mass vaccination campaign was completed. The outbreak was largely confined to the eastern half of the country (MacCarthy Island and Upper River Divisions). In nine survey villages in this area (total population 1,531) the attack rate was 2.6--4.4%, with a mortality rate of 0.8%, and a case fatality rate of 19.4%. If these villages are representative of the total affected region, there may have been as many as 8,400 cases and 1,600 deaths during the outbreak. The disease incidence was highest in the 0- to 9-year age group (6.7%) and decreased with advancing age to 1.7% in persons over 40 years. Overall, 32.6% of survey village inhabitants had YF complement-fixing (CF) antibodies. The prevalence of antibody patterns indicating primary YF infection decreased with age, in concert with disease incidence. The overall inapparent:apparent infection ratio was 12:1. In persons with serological responses indicating flaviviral superinfection, the inapparent:apparent infection ratio was 10 times higher than in persons with primary YF infection. Sylvatic vectors of YF virus, principally Aedes furcifer-taylori and Ae. luteocephalus are believed to have been responsible for transmission, at least at the beginning of the outbreak. Eighty-four percent of wild monkeys shot in January 1979 had YF neutralizing antibodies, and 32% had CF antibodies. Domestic Aedes aegypti were absent or present at very low indices in many severely affected villages (see companion paper). In January, however, aegypti-borne YF 2.5 months into the dry season was documented by isolation of YF virus from a sick man and from this vector species in the absence of sylvatic vectors. Thus, in villages where the classical urban vector was abundant, interhuman transmission by Ae. aegypti occurred and continued into the dry season. A mass vaccination campaign, begun in December, was completed on 25 January, with over 95% coverage of the Gambian population. A seroconversion rate of 93% was determined in a group of vaccinees. This outbreak emphasizes the continuing public health importance of YF in West Africa and points out the need for inclusion of 17D YF vaccination in future programs of multiple immunication.

Equine Getah virus infection: isolation of the virus from racehorses during an enzootic in Japan.

Abstract: A primary enzootic of equine Getah virus infection involving 722 of 1,903 racehorses occurred at a training center in Japan between September and November of 1978. Sixty-two viral agents were isolated from the plasma of 209 sick horses which exhibited pyrexia with rectal temperatures ranging from 38.5--40 degrees C, urticarial rash on various portions of the body, and edema of the hind legs. The viruses were antigenically related to the AMM 2021, Haruna, and Sagiyama strains of Getah virus. Infection and disease were produced experimentally in horses when inoculated by the intramuscular or intranasal routes.

Transmission of dengue 1 and 2 viruses in Greece in 1928.

Abstract: In August-September 1928 approximately 650,000 residents of Athens and Piraeus contracted dengue fever, and 1,061 died. We were interested in the etiology of this severe epidemic in which many cases resembled dengue hemorrhagic fever or the dengue shock syndrome, and have attempted a retrospective seroepidemiological study. Serum specimens were obtained from 111 residents of Athens or Piraeus who were born in 1927 or 1928, and were studied by plaque reduction neutralization test for antibodies to dengue 1–4 viruses. Of 75 persons born in 1928, 20 (27%) had monospecific dengue 1, 10 (13%) had monospecific dengue 2, and 1 (1%) had dengue 1 and 2 neutralizing antibodies. When prevalence of neutralizing antibody was analyzed by month of birth in 42 individuals, evidence of both dengue 1 and 2 infections was found in persons born in January–July, but only dengue 2 antibody was detected in those who were born after July. This study dates dengue 1 and dengue 2 transmission to 1928, allowing for the possibility that sequential infections with these viruses could have played a pathogenetic role in the outbreak.

Enzyme-linked immunosorbent assay (ELISA) in the serodiagnosis of hydatid disease

Abstract: An enzyme-linked immunosorbent assay (ELISA) was adapted for the indirect serological measurement of anti-Echinococcus antibodies in human hydatid disease. Both the tube method and the microtitration procedure were used successfully. However, the tube test with a purified hydatid fluid fraction appears to be the method of choice. ELISA results are comparable to those found in the indirect hemagglutination test and with the agar gel methods (double diffusion and immunoelectrophoresis), but false positive results were observed with the sera of patients with schistosomiasis or liver cirrhosis. ELISA has proved to be a sensitive quantitative procedure for the serodiagnosis of human echinococcosis, even though it has not been shown in our study to be more sensitive than the classical serological procedures such as indirect hemagglutination. It can be concluded that ELISA should be considered not as an alternative but as a useful addition to the range of immunodiagnostic tests available for serodiagnosis of hydatid disease.

Evidence of Rickettsia prowazekii infections in the United States.

Abstract: From January 1976 through January 1979 serum specimens from 1,575 individuals were received at the Center for Disease Control and tested for antibodies to rickettsiae Of these, sera from eight persons gave serological results indicative of recent infections with epidemic typhus rickettsiae (Rickettsia prowazekii) Five of the persons were from Georgia, and one each was from Tennessee, Pennsylvania and Massachusetts The illnesses occurred during the winter, chiefly in persons living in a rural environment The clinical picture was compatible with louse-borne epidemic typhus There was no apparent contact with human body or head lice, and no cases occurred in patient contacts, indicating that infection was not associated with the classic man-louse-man cycle of epidemic typhus Two of the eight patients had contact with flying squirrels, suggesting that they became infected from this known extrahuman reservoir of R prowazekii

Serologic cross-reactions with sera from patients with echinococcosis and cysticercosis.

Abstract: Serum specimens from persons with pathologically confirmed Echinococcus granulosus hydatidosis and Taenia solium cysticercosis were tested in indirect hemagglutination tests using both Echinococcus and Taenia antigens. There were cross-reactions with most sera, and it was not possible to distinguish specific reactions by comparing titers with the homologous or heterologous antigens. Using immunoelectrophoresis or double diffusion tests with E. granulosus antigens, the Echinococcus-specific arc 5 was demonstrated in 11 of 21 hydatidosis sera and in 1 of 20 cysticercosis sera.

Toxoplasma gondii in Costa Rican cats.

Abstract: Toxoplasma gondii infection of cats was studied in seven localities in Costa Rica. A total of 237 cats were tested for antibody by the dye test, and for oocysts by injection into mice. Toxoplasma was isolated from 55 (23%) and antibody was found in 109 (46%). Sixty percent of cats were infected as shown by shedding or antibody. Of the 55 isolations, 64% were from kittens without antibody and 36% from kittens with antibody. Almost half of the Toxoplasma isolations were made from the feces of kittens weighing less than 600 g, 35 cm in length, or under 2 months of age, of which 41% were shedding Toxoplasma. Six hundred and seventy-six homeowners in the seven towns were questioned about the number of owned and stray cats visiting their houses, the cats' pattern of roaming, food sources, types of food foraged, defecation sites outdoors and indoors, and location of fecal deposits in houses. Seventy-six percent of houses reported cats, which averaged 2.1 cats per house; about 80% were strays, and 99% lived outdoors part or all of the time. The cats visited from 5–12 (average 6) houses, foraging for food in garbage, hunting mice, rats, sparrows and insects. Of the 516 households reporting cats, 29% supplied some food in addition. In 14% of these houses cats defecated in the house, including the false attic and crawl space; they commonly defecated in front and backyards of houses, close to human habitation and accessible to intermediate hosts.

Role of anaphylactic antibodies in immunity to schistosomes.

Abstract: Antibody-dependent cell-mediated cytotoxicity in reinfection immunity to schistosomes in the rat involves either IgG2a anaphylactic antibody and eosinophils or IgE antibody and macrophages. The first system requires two signals, one by the antibody through the eosinophil Fc receptor, another by mast cells through the release of mediators among which is ECF-A. IgE antibody complexed with schistosome antigen binds to an IgE-specific receptor on the macrophage and triggers the cell to release enzymes and superoxide. Immunity in rat schistosomiasis is antibody-dependent, abolished in anti-mu treated neonate rats or by passive serum transfer after selective depletion of either IgG2a or IgE. The two anaphylactic antibody-dependent cell cytotoxicity systems are in a permanent balance in immune rats, eosinophils being blocked by IgG2a immune complexes when this cell is inefficient. Anaphylactic antibodies thus play a key role in triggering and modulating effector cell function.

Experimental Rabies in the Vampire Bat

Abstract: Vampire bats were inoculated intramuscularly and subcutaneously with varying doses of rabies virus to simulate bites by rabid animals in nature. Daily saliva samples were then taken from these animals to determine whether they excreted virus and for how long. Vampire bats appear to react to rabies virus as do other animals, with variable incubation periods, some excretion of virus in the saliva, but no prolonged excretion "carrier state."

Prevention of scrub typhus. Prophylactic administration of doxycycline in a randomized double blind trial.

Abstract: We conducted a prospective randomized double blind study on the effects of doxycycline as a prophylactic antibiotic against scrub typhus. A total of 1,125 military subjects was followed for periods as long as 5 months of exposure in a hyperendemic focus in the Pescadores Islands of Taiwan. Oral 200 mg doses of doxycycline (Vibramycin) or placebo were given once each week throughout the trial. The incidence rate of scrub typhus in the placebo group was 2.5 times greater than that of the group taking doxycycline (P = 0.11). When subjects who failed to comply with scheduled administration of doxycycline were removed from the analysis, the incidence rate of scrub typhus in the control group was five times greater than that in the drug group (P = 0.04). The rates of infection with Rickettsia tsutsugamushi and of sick call reports were the same in experimental and control groups. The drug was well tolerated in pretrial tests and complaints were negligible during the conduct of the trial. Doxycycline appears to be an excellent antibiotic for the prevention of scrub typhus among personnel exposed to high risk of infection with R. tsutsugamushi.

Human Toxoplasmosis and Cat Contact in Costa Rica

Abstract: We studied the prevalence of antibody to Toxoplasma gondii in 883 Costa Ricans between the ages of 15 and 26 years (mean 20.3). There were seven populations, two rural and five urban. The overall antibody prevalence was 61.4%. Because antibody prevalence was 57.1% in the 14 people who ate raw meat, and 61.6% in the 294 people who consumed raw eggs, meat and eggs could be excluded as important modes of transmission. We ascertained the presence of cats, type of soil contact, and flooring in the kitchen for every residence in which each individual lived from birth until interviewed. The 66% of people who indicated contact with cats had an antibody prevalence of 64%, and those without contact 56% (P = 0.02). In six of the seven populations, we found a positive correlation between cat contact and antibody prevalence; hence these six were studied together, and San Ramon, with a negative correlation, was examined separately. In the San Jose metropolitan population and in the total urban sample, cat contact was associated with a significantly higher antibody prevalence (P < 0.01). It was found that humans, even without acknowledged soil contact, acquire infection inside houses, especially with cement floors, when cats defecate in the house. Humans also acquire infection in or around houses with wooden floors, where the crawl space is an often unrecognized refuge of cats and a source of persistent soil contamination. San Ramon was the urban area with the highest human-cat contact (77%) and with the highest antibody prevalence in cats (75%). Although suggesting equal opportunities for infection, irrespective of cat contact, we cannot be certain in a retrospective study in which most of the infections took place an average of 15 years earlier. The most frequent antibody titer in our Costa Rican population was 1:1,024 (21%), much higher than the most frequent titers in a Colombian (1:64 to 1:128) and a U.S. population (1:16) of comparable age.

Phaeomycotic cyst. A clinicopathologic study of twenty-five patients

Abstract: The clinical and pathologic features of 25 cases of phaeomycotic cyst, collected at the Armed Forces Institute of Pathology between 1959 and 1978, are described. Phaeomycotic cyst is infection of the deep dermis and subcutaneous tissue by dematiaceous (brown) fungi. Species of Phialophora were most frequently isolated from these lesions. Synonyms for phaeomycotic cyst are--among others--phaeomycosis and phaeosporotrichosis. Phaeohyphomycosis includes phaeomycotic cyst and some other mycoses. The term "phaeo" is derived from the Greek phi alpha iota omicron sigma, meaning grey or black, and refers to the brown color in vivo and in vitro of these fungi. Phialophora species are world-wide saprophytes, common in soil, decaying wood, and vegetation. They have low virulence and low pathogenicity, and are inoculated along with slivers whose retention is probably an important causal factor in establishing infection. Proliferation of the fungi provokes a mixed suppurative and granulomatous reaction which remains localized. Early the characteristic histopathologic picture is one of multiple stellate abscesses. These progress to a single circumscribed lesion with a central cavity filled with pus and surrounded by a fibrous wall. There are no systemic signs or symptoms, regional lymph nodes are not involved, nor has any patient had systemic spread. The infection is rare but tends to be more common in warm climates. No race, sex, or age group is predisposed, but patients with immune deficiency or debilitating disease are at increased risk. In older publications phaeomycotic cysts have been described as variants of chromomycosis, sporotrichosis, and mycetoma. Phaeomycotic cysts, however, do not provoke hyperplasia of the epidermis or ulceration--characteristic features of both chromomycosis and sporotrichosis, nor do phaeomycotic cysts form sinus tracts or contain grains--both typical features of mycetoma. The strictly localized abscess or "cyst" is the characteristic feature of phaeomycotic cysts.

Effect of rearing temperature on transovarial transmission of St. Louis encephalitis virus in mosquitoes.

Abstract: Female Aedes albopictus and Aedes epactius infected by inoculation with St. Louis encephalitis (SLE) virus transmitted virus transovarially to their F1 progeny. With Ae. epactius, minimal infection rates (MIR) in F1 larvae were similar for progeny reared at 18 (+/- 1) degree C or 27 (+/- 1) degree C, whereas, MIR's were significantly higher in F1 adults reared at 18 degrees C, than they were in F1 adults reared at 27 degrees C. Use of different strains of SLE virus appeared to influence transovarial transmission of virus by Ae. albopictus, but not by Ae. epacticus. Transovarial transmission of SLE virus was not demonstrated with colonized strains of Aedes dorsalis, Ades sierrensis, Ades triseriatus, Ades vexans, Culex pipiens, Culex quinquefasciatus and Culex tarsalis, and field strains of Ae. vexans.

Plasmodium falciparum in vitro: determination of chloroquine sensitivity of three new strains by a modified 48-hour test.

Abstract: Three recently isolated African strains of Plasmodium falciparum were tested in vitro for their response to chloroquine. Both the 48-hour method described earlier and a modified 48-hour test were used, yielding comparable results. Strain FCR-7/Kenya, isolated from a clinically chloroquine-resistant case, was more resistant to the drug in vitro than the two other strains (FCR-8/West Africa and FCN-1/Nigeria, both isolated from chloroquine-sensitive cases). Complete inhibition of parasite growth occurred for strain FCR-7/Kenya in a drug concentration range ten times higher than for strains FCR-8/West Africa and FCN-1/Nigeria. In the modified 48-hour test, a lower erythrocyte suspension (2%) allows continuous growth of the parasites over a 48-hour cycle without necessitating change in medium. It thus offers distinct advantages for routine laboratory work as well as for potential field trials.