The American Journal of Tropical Medicine and Hygiene - Volume 1, Issue 4, July 1952

• 1.  Two hundred patients examined at the proctoscopic clinics of the medical departments of the Louisiana State University and Tulane Medical Schools, were studied for the presence of Endamoeba histolytica infection.
• 2.  The increase of incidence of amebiasis (from 4 to 13 per cent) found in patients presented in the proctoscopic clinics over that reported from the parasitology laboratory of Charity Hospital can be accounted for in several ways.
  • a.  Method of keeping records.
  • b.  Selection of cases.
  • c.  Multiple examinations of the cases studied.
• 3.  Proctoscopic examinations frequently disclose findings of considerable importance and so have a distinct value in themselves. The above data, however, indicate that adequate examination of properly collected fresh stools is somewhat, though not significantly, more efficient than the examination of proctoscopic material for the diagnosis of intestinal amebiasis.
• 4.  Direct examination of material removed during proctoscopy revealed a few more E. histolytica parasites than did examination of iron hematoxylin stains made on the same material.
• 5.  No true superiority of method was demonstrated but it was again shown that the use of additional procedures and repeated examinations reveal an increased number of amebic infections.

A satisfactory method for the diagnosis of amebic infection by culture has been evolved by the modification of the standard liquid media (St. John's and Balamuth's). The study has been based on the examination of 50 fecal specimens.

The response of E. histolytica to a stimulating principle present in dead bacterial cells has been shown to be proportional to the amount added. The factor is rather labile to heat, to alkali, and to oxidation, but stable in presence of formaldehyde. There are some indications that it may be a labile metabolic intermediate.

Fumagillin, orally, is active directly against E. histolytica in macaques and man. In man, at a total dosage of 100 mgm. over 12½ days, 9 of 10 cyst passers remained clear during 3 months; 50 mgm. total cleared only 4 of 10 patients. In monkeys, total dosage of 250–625 mgm./Kg. over 5 to 10 days was required to keep 12 of 19 animals cleared during 3 months.

No signs nor symptoms of intolerance were noted in man. In monkeys, one showed retention of sulfobromophthalein while another had increased blood urea nitrogen after therapy.

Other laboratory findings were not significant in either monkeys or man. Nonpathogenic intestinal parasites did not clear consistently in either mammalian species. There was close correlation between results in monkeys and man generally.

A comparative study with untreated controls and with terramycin and thiocarbarsone treated patients was made. Fumagillin was most potent and appeared to be most active in chronic, drug refractive, intestinal amebiasis.

The effect of two different compounded diets on experimentally induced Endamoeba histolytica infection in two hosts, the rat and the guinea pig, has been studied and the results reported here.

When the guinea pigs were maintained on the modified guinea pig (MGP) diet, almost 100 per cent of the animals died of the infection with a mean day of death of 8.4 days, and an average degree of infection of 3.9 out of a possible 4.0. When the rat breeder diet was fed to the guinea pigs only 78 per cent of the animals died of the infection with the mean day of death of 14.8 days and an average degree of infection of 3.3. The differences produced by the two diets were statistically significant.

In rats both diets produced a high incidence of infection and a high average degree of infection.

The data presented here, along with the work already reported from our laboratory, add further evidence to that reported by others, that diet influences the course of amebic infection in rats and guinea pigs.

An attempt has been made to assess the degree of resistance to reinfection with Endamoeba histolytica following elimination of previous amebic infection. Inoculation was made by intubation per anum of trophozoites in dysenteric aspirates obtained from infected dogs.

The initial induced infection rate of amebiasis in dogs was 85 per cent. Despite repeated attempts to reestablish infections in animals whose initial infection had been terminated, using equivalent or greater inocula, only 17 per cent could be reinfected. This indicates the development of acquired immunity to reinfection with E. histolytica in dogs.

The resistance to reinfection in dogs was active against both homologous and heterologous strains of E. histolytica. The strains employed differed distinctly in their culturability.

The tested duration of immunity to reinfection ranged from ten weeks to 9½ months. Over the periods observed, no animal lost its resistance to reinfection once it was established following an initial infection.

A small series of animals which received pre-inoculation blood transfusions from dogs which had become refractory to reinfection with E. histolytica, thus far has shown a lower infection rate than that of animals which were not transfused. This suggests the possibility of passive transfer of immunity in experimental amebiasis in dogs.

The cysticidal efficacy of acetic acid against cysts of the NRS strain of Endamoeba histolytica has been studied at temperatures between 25°C. and 50°C. with acid concentrations of 1 per cent, 2.5 per cent, and 5 per cent. The importance of the temperature factor has been demonstrated.

Evaluation of the acetic acid in tests against cysts in suspensions indicated the potential value as a cysticidal procedure of 15 minutes exposure to 5 per cent acid at 30°C. and of 5 minutes exposure to 2.5 per cent acid at 45°C. No cyst survival was evident under these conditions. One brand of vinegar tested gave similar results at the higher temperatures.

The importance of checking the survival of cysts actually remaining on vegetables after such treatment has been demonstrated. By a procedure of blending cyst-contaminated, treated lettuce in a Waring blender, estimates were made of numbers of cysts remaining on lettuce after treatment, and their viability was tested by inoculating into medium the filtrates and “mash” of the blended lettuce. Such experiments indicated that a few viable cysts remained on lettuce in 2 of 3 tests after 15 minutes exposure to 5 per cent acid at 30°C. and in 1 of 5 tests after 5 minutes exposure to 2.5 per cent acid at 45°C. In the latter case especially, the percentage of cysts surviving was apparently very low.

The treatment removed the greater part of the original cyst contamination from lettuce. The usefulness of the procedure is limited by the fact that some vegetables, especially leafy greens, deteriorate after a few hours storage and should be used as soon as possible after treatment. It is concluded that the use of acetic acid on frese vegetables would provide considerable, but not necessarily complete, protection against E. histolytica cysts present on the foods.

The presence of T. ariarii in the hemolymph and in the salivary glands of R. prolixus (both naturally and experimentally infected) is a rather constant feature. Furthermore the ability of R. prolixus to transmit T. ariarii through the bite has been proved. These data seem to point to a cyclical development of T. ariarii in R. prolixus, in which the flagellates are first present in the intestine after the infective meal. Later on, some of the parasites migrate to the hemolymph and from this to the salivary glands. From the glands the trypanosomes can be transmitted—through the bite—into new vertebrates.

Diasone (0.5%) and Avlosulfon (0.1%), when administered in the diet, protect the majority of white mice from death in an otherwise rapidly fatal toxoplasmosis even when therapy is delayed by ⅓ of the survival time of the untreated animals. Sulphetrone used similarly at 1.5% is without effect and only slightly protective when used at 3.0%. None of the drug controls showed any toxic reactions at these dosages. The carrier condition seems to have been eliminated certainly in 7 and probably in an additional 3 out of the 11 cases investigated. Since our results surpass those previously reported for Diasone and for Avlo-sulfon, it is possible that the method of administration (intermittent dosage following continuous dosage) contributes to the increased effectiveness.

Malaria is endemic in all the region between the slopes of the eastern range of the Andes and the borders with Venezuela and Brazil. The malaria indexes vary according to the distribution of the anopheline species; of the 28 anophelines found in the area, A. darlingi has proved to be, as in other parts of South America, the most effective vector; its distribution, however, is restricted to certain areas. Most of the savanna country of Eastern Colombia is free from darlingi and, though the savanna anophelines such as A. pessoai, A. peryassui and A. parvus are extremely abundant throughout the nine months of the rainy season, there are always low malaria indexes.

The fertility of the soil in the areas covered by darlingi has attracted in recent years a considerable number of agricultural laborers from other parts of the country, but the poor soil of the savannas is hardly fit for agriculture and there a more stable population has been devoted mainly to cattle breeding. Malaria has a rural character throughout Eastern Colombia. The house-haunting anophelines, including darlingi, seldom venture into the urban areas; they are not found resting in houses during the daytime, thus greatly reducing the effect of DDT. A. darlingi, though more closely associated with man than the other anophelines, is nevertheless found also in uninhabited areas and feeds normally on wild animals.

Complete mosquito feedings were done on 24 patients with early primary parasitemias of Plasmodium vivax (Chesson strain). The average infection produced infected mosquitoes on the fourth day of demonstrable parasites, two days before gametocytes could be discovered by normal examination of blood smears, two days following the onset of fever (100°F. or above), and about one day previous to the first fever of 104°F. or more.

It is concluded that these early parasitemias may be of epidemiological importance, in that, even in endemic areas where good therapeutic measures are available, the primary attack would provide a reservoir for mosquito infection before it could be terminated or suppressed. In indigenous populations of endemic areas it would be unusual for the naturally acquired vivax infection to be terminated or suppressed before the infected individual became a potential source of mosquito infections.

An epidemiological investigation revealed that in a district of the Province of Teramo (Abruzzo, Italy), 23.7 per cent of the population showed either active lesions or the scars of oriental sore. Two subsequent annual applications of residual DDT inside houses and stables were sufficient to stop the transmission of the disease. The porportions of new cases in the treated zone were 7 per thousand after the first, and 1.3 per thousand after the second application of DDT, compared with 34.7 and 40.4 per thousand respectively in the untreated zones.

After the first DDT spraying Phlebotomus had disappeared, with an occasional exception, and after the second treatment no Phlebotomus at all was observed either indoors or outside in the treated zone, while these insects continued abundant in the untreated areas.

Five antibiotics, alone and in combination with penicillin, were under observation for in vivo effectiveness against Trichomonas vaginalis.

The five antibiotics were aureomycin, chloramphenicol, penicillin, dihydrostreptomycin and terramycin.

In this series of cases no effect on the vaginal trichomonads could be demonstrated by the antibiotics employed in therapeutic amounts.

• 1.  Six patients infected with Balantidium coli, three of whom also harbored Endamoeba histolytica, were treated with aureomycin and all remained negative for these infections in frequent post-treatment examinations of two to twelve weeks' duration.
• 2.  In all cases B. coli disappeared within four days of initiation of treatment and it is probable that a shorter course of treatment might prove equally effective against this infection.

The purpose of the present paper is to report two more cases of Rocky Mountain spotted fever, which brings to four the total number of cases reported on the Isthmus of Panama. Both patients were treated with antibiotics and recovered. The diagnosis in both cases was confirmed by the complement fixation test.

Report of the Cases. Case No. 1—J. W., yellow race, female, 65 years old, was admitted to the Panama Hospital the 26th of January, 1951, because of a remittent fever of six days duration, with rhinitis, headache, nausea and vomiting.

The physical examination revealed a discrete maculo-papular rash on the lateral wall of the thorax, the abdomen, and the extremities. No petechial spots were observed. The tongue was coated and the breath was unpleasant. The liver was two fingerbreadths below the right costal margin upon inspiration and was not tender.

A survey of 10 experimental areas on the islands of Tahiti and Maiao revealed an incidence of microfilarial carriers of 33% in people over 5 years of age. Males had an average microfilarial density in capillary blood approximately twice that of females. The microfilarial density increased with age to a peak in the 40–49 year age group. Forty-one per cent of the persons examined over one year of age had clinical filariasis, the first attack occurring most often in the age period 20–29 years. Adult specimens of filaria were recovered from two individuals and both these and the microfilariae resembled descriptions of Wuchereria bancrofti from other regions.

Nine species of mosquito were found, the most common being the day biting Aedes pseudoscutellaris (the principal vector), and the night biting Culex quinque-fasciatus.

Diethylcarbamazine (Hetrazan), at a dosage of 2 mg./kg. T.I.D. for 7 days, reduced the microfilarial incidence from 34.4 per cent before treatment to 19.6 per cent at the end of a year and the microfilarial density of the remaining treated positive subjects was less than 10 per cent of the original concentration. There was no reduction in untreated comparison areas. Treatment, however, did not reduce the frequency or severity of clinical filariasis. No seasonal variation in the frequency of attacks of lymphangitis was observed. The drug was well tolerated, although more than half the subjects showed transitory reactions. The treatment campaign appeared to have no effect on the mosquito population, nor did DDT and sanitation, in the course of one year, have an effect upon microfilarial rates or densities, although the evidence suggests that DDT and sanitation reduced the adult mosquito population. No evidence of mosquito resistance to the toxicant was observed during one year.

In the highly endemic area, a combination of treatment, sanitation and use of insecticides would seem to offer the best likelihood of success in the control of filariasis, and studies are being continued in Tahiti to determine the most effective mode of application and association of these measures.

• 1.  Une enquête portant sur la population de 10 régions expérimentales dans les îles de Tahiti et Maiao a révélé une forte proportion de filariose de Bancroft parmi une population de 1265 personnes examinées. Le nombre de porteurs de microfilaires à partir de l'âge de cinq ans était 407 soit 33.17%.
• 2.  Quarante pour cent des hommes dans les régions 1 à 7 et 33% des femmes etaient porteurs de microfilaires, La densité moyenne des microfilaires par 20 mm3 de sang chez 171 hommes était approximativement deux fois plus élevée que chez 115 femmes, soit respectivement 130,4 et 66,7.
• 3.  Le chiffre moyen de microfilaires par 20 mm3 de sang chez les individus positifs était 127,7 et augmentait avec l'âge pour atteindre un maximum de 268 entre 40 et 49 ans. Le nombre le plus élevé trouvé a été 1094 microfilaires chez un homme de 42 ans et l'enfant le plus jeune trouvé positif fut une fille de 14 mois.
• 4.  121 ou 32% des 376 personnes au-dessus d'un an dans les regions 1 à 7, alors que 77 ou 46,7% des 165 personnes au-dessus de 3 ans à Maiao présentaient des signes cliniques. Dans un groupe de 85 personnes avec lymphangite, le nombre le plus élevé, 30 ou 35,3% ont présenté leur première attaque de lymphangite entre 20 et 29 ans.
• 5.  Neuf espèces de moustiques ont été rencontrées dans les régions experimentales au cours de l'étude entreprise. Les deux espèces les plus communes sont le moustique piquant le jour, Aedes pseudoscutellaris qui est le vecteur principal, et le moustique piquant la nuit, Culex quinquefasciatus.
• 6.  Les lieux de reproduction principaux sont les noix de coco mangées par les rats, les ornières et les marécages, les pirogues, les trous d'arbres, les boîtes de conserve et d'autres récipients moins importants.
• 7.  220 animaux furent examinés pour rechercher les microfilaires possibles; 26 ou 56,5% des 46 chiens et 4 ou 12,5% des 24 chats ont été trouvés porteurs de microfilaires de Dirofilaria immitis.
• 8.  Des spécimens de filaires adultes furent trouvés chez deux sujets, l'un habitant Makatéa et l'autre la région 7. Le parasite ne parait pas differer morphologiquement de Wuchereria bancrofti (Cobbold).
• 9.  Les microfilaires des habitants de Tahiti ou d'autres îles d'Océanie Francaise, ont de même été trouvées indifferentiables des microfilaires de W. bancrofti provenant de plusieurs autres territoires.
• 10.  Les régions oú l'Hétrazan fut administré oralement à raison de 2 mmg. par kilogramme de poids, trois fois par jour, pendant sept jours, et où 34% des habitants étaient porteurs de microfilaires, ont montré une réduction de ce pourcentage à 19,4% à la fin de l'année.
  
  Dans les régions ou l'Hétrazan n'était pas administré aucune réduction n'est apparue.
• 11.  Il n'existe pas de réelle preuve dans cette étude que l'Hétrazan réduise la fréquence ou la séverité des signes et symptômes de filariose. De même qu'il n'y a pas de preuve que les attaques de lymphangite soient plus fréquentes pendant certaines saisons de l'année.
• 12.  l'Hétrazan, ainsi administré, a été bien toleré par la plupart des patients. Cependant, deux types de réactions transitoires furent observés. Le 1er groupe de réaction survient entre le 1er et 3ème ou 4ème jours de traitement, les symptômes les plus communs étant la fièvre, souvent accompagnée de fatigue, céphalée, anorexie, prurit, douleurs abdominales, nausée, arthralgies. Le second groupe de réactions survient entre 3 et 15 jours et consistent en prurit, adénopathies douloureuses, urticaire et éruption bulleuse.
• 13.  Appliquée pendant une année l'administration d'Hétrazan n'apparait pas avoir d'effet sur la population des moustiques. Aussi les mesures de contrôle du moustique, DDT et assainissement n'avaient pas d'effet sur la fréquence ou la densité des microfilaires.
• 14.  Il est prouvé que le DDT réduit la population des moustiques.
• 15.  Dans des régions de haute endémicité, l'administration d'Hétrazan à toute la population combinée avec le contrôle des moustiques par assainissement et emploi judicieux du DDT est la méthode la plus sure de contrôle de la filariose. Cependant il n'est pas toujours possible d'employer toutes les mesures ensemble et c'est le but des études en cours a Tahiti, de determiner les combinaisons possibles et efficaces qui peuvent être appliquées.

The density of Aedes pseudoscutellaris and the percentage of infection with the developing stages of the nonperiodic form of Wuchereria bancrofti are combined into an “index of transmission” in different sites. Evidence is presented, on this basis, that transmission, in American Samoa, is primarily in the bush, along the trails and in the plantations. Transmission within the village proper is of little concern. It is suggested that in other Pacific islands, where this same infection and same mosquito vector occur, the possible role of this same type of environment in the transmission of the disease should be considered.

INTRODUCTION

The control of schistosomiasis is one of the important problems in modern tropical medicine. An obvious method of combating the disease is to find practical molluscacides to eliminate the snails that serve as intermediate hosts. This approach is of particular interest to the Armed Forces because men operating through an endemic area are very apt to become infected. For this purpose it is important to have a method of control that quickly reduces the intermediate host population to a point where exposure to cercariae is reduced to a minimum. Under these circumstances one does not often have to consider the repopulation of the snail colonies, elimination of reservoir hosts, treatment of local cases in man, etc.

In 1944 and 1945 American troops had their first experience with schistosomiasis japonica in the Leyte campaign. Up to that time copper salts, especially copper sulphate and copper carbonate, were considered the most effective agents for use on aquatic snails.

A study was made of the endemic area of schistosomiasis mansoni at Hato Mayor in the Dominican Republic. Australorbis glabratus, the snail host for Schistosoma mansoni, seems to have a very restricted distribution in the vicinity of Hato Mayor. Numerous A. glabratus were found in streams close to the town but none was found in other streams up to 20 kilometers from the town. Many of the snails harbored cercariae which developed into adult S. mansoni in mice. Examination of a single stool from each of 243 children between the ages of 5 and 15 living in Hato Mayor revealed 52 infections with S. mansoni.

It is concluded that a serious endemic focus of schistosomiasis mansoni exists in the vicinity of Hato Mayor, and that the disease is being acquired by a relatively large proportion of the children of the town. Because the endemic area is apparently restricted to narrow geographic limits, it is considered especially well suited for a study on the use of molluscacides in the control of schistosomiasis mansoni.

One hundred and twenty five Honduran children were treated for ascariasis with 1-diethylcarbamyl-4-methylpiperazine hydrochloride (Hetrazan®) in a syrup which contained 30 mg. of the drug per cc. Of the dosages employed, the most effective was 12 mg. per pound of body weight daily for 4 days; in 80 per cent of 30 cases this amount resulted in absence of ascaris eggs from concentrated (zinc sulfate flotation) stools on both of two post-treatment examinations. Smaller amounts gave less satisfactory results. Eighteen mg. per pound of body weight appeared to be too toxic.

Factors effecting the apparent cure rate are discussed. The most important are the criteria of cure and the season of the year during which the study is done.

It is concluded that when it is undesirable to fast or purge, diethylcarbamazine may be a satisfactory vermifuge. It should be of particular advantage in private practice. However, it is not an ideal compound for mass treatment because multiple doses are necessary.