High Malaria Incidence Research Articles

Malaria imported to the United States from Vietnam. Chemoprophylaxis evaluated in returning soldiers.

In addition to the high incidence of malaria among the American millitary in Vietnam, there has been a progressive increase in the number of imported cases occurring in such persons following their return to the United States. Most of these cases are due to Plasmodium vivax infection. The combined chloroquine-primaquine tablet, taken once a week for 8 consecutive weeks, is effective for radical cure for vivax infection, and all returnees supposedly complete this course of therapy. This study was made to assess the effectiveness of this prophylactic program. A questionnaire survey was made of 671 Army officers and enlisted men regarding malaria prophylaxis. Of the total group, 70% failed to complete the full course of therapy. The rate of failure among officers and enlisted men was nearly equal. There was no predominant cause for failure, but common reasons given included 1) forgetting to take medication, 2) loss of pills, 3) not receiving sufficient number of pills, and 4) untoward side-effects of therapy. Persons stationed in “high-risk” malaria areas were more likely to complete therapy successfully, although previous clinical malaria did not improve the success rate in such affected persons. This extremely high failure rate of the current malaria chemoprophylaxis program would appear to be a significant factor contributing to the high incidence of imported malaria occurring in the United States.

Studies on Man-Vector Contact in Some Malarious Areas in Colombia

The frequency of man-biting by mosquitos depends upon the amount of contact between man and mosquito, which in turn depends upon the behaviour patterns of both. In order to examine these relationships in an area with a high incidence of malaria, a study was made in 1965 of the nocturnal movements and of mosquito biting habits in five localities in the malarious area of Colombia that were in the thirteenth or fourteenth cycle of biennial DDT spraying.The populations were classed into five age- and sex-groups, i.e., men and women over the age of 15 years, boys and girls from 5 to 15 years, and children under 5. A number of differences in the habits of these groups were discovered in relation to time spent indoors or outside, but close to, the house.The habits of the four main anopheline vector species were studied in relation to human activities. For three of the species (A. albimanus, A. darlingi, A. nuneztovari) it is suggested that a low relative importance of outdoor biting is caused not by a density-dependent factor but by an anopheline gonotrophic cycle or by relative humidity or both. The fourth species (A. punctimacula), common only at one locality, displayed a complex pattern of biting behaviour with, however, a much greater frequency of outdoor biting than in the other species.It is considered that in these localities malaria is probably transmitted mainly inside sprayed houses by vectors that are susceptible to the insecticides in use but which are not sufficiently reduced in numbers or in life-expectancy to interrupt the transmission of the parasite.

BLOOD GROUPS, SERUM GENETIC FACTORS, AND HEMOGLOBINS IN NEW HEBRIDES ISLANDERS.

A sample of 200 New Hebrides Islanders has been tested for 13 blood group systems and for haptoglobin, transferrin, and Gm types.The population is characterized by a high B gene frequency, high N, and S associated only with N. The Rh results show very high R1 with one example of the genotype r′r′. This is the fourth example we have encountered in Polynesians and Melanesians in whom the rr genotype has never been recorded.The Lewis groups show the consistently high Le(a‐b‐) frequency found in Southwest Pacific Island Populations.As in the Solomon Islanders, the absence of abnormal hemoglobins is noted in relationship to a high malaria incidence.

Atabrine and Plasmochin in the Treatment and Control of Malaria

Summary 1. The effects of Atabrine and Plasmochin were observed in a highly malarious area of Calhoun County, Georgia, where a thick blood smear index of school children in six districts showed 80.1 per cent positive for malaria in October, 1932. 2. Because of the high incidence of subtertian malaria, 0.01 gram Plasmochin was given three times a week throughout the malaria seasons of 1933 and 1934, and Atabrine 0.1 gram three times a day (three tablets) for five days, whenever monthly blood smears showed positive, or clinical symptoms developed. 3. Throughout both seasons there was a satisfactory control of gametocyte productions, which it is believed, was due to Plasmochin. 4. Most striking results were obtained in the reduction of malaria infection in the treated area as compared with an untreated district immediately adjoining the treated area. This was due to the effect of Atabrine. At the end of the 1933 malaria season the rate in the treated area was 10.9 per cent, as compared with a rate of 60.3 in the untreated area. In October, 1933, those in the untreated area received full course treatments of Atabrine. there was little variation in the rate during the early part of 1934, but as the season advanced there was an increase to 28.8 in the area originally untreated, whereas in the regularly treated area the incidence was only 8.8 at the close of the season in October. 5. Atabrine has been found particularly effective in the sterilization of carriers. Of 186 positive cases before treatment in May and June, 1933, only 15 were positive in October. Of the 15 cases, only one was positive in July, 1934 and 5 in October. There was, therefore, a reduction of 96.8 per cent at the height of the malaria season in October, 1934. 6. The beneficial effects of both drugs are probably accountable for the lower infection rates among those individuals originally negative in the treated area, as compared with a similar group in the untreated area. Likewise, the percentage of those who were orginally negative and remained negative throughout a two year period was very considerably greater in the treated area as compared with a similar group in the untreated area (table 3). These observations are believed to be of considerable importance in malaria prevention, for they demonstrate the value of carrier control programs in the cure and prevention of malaria. 7. With winter intervening in the temperate zone to aid in malaria prevention, it is believed that the effectiveness of Atabrine and Plasmochin marks an important advance in the control of malaria in this latitude. 8. The short course of treatment necessary, the effectiveness of Atabrine as a schizonticide, and the efficacy of Plasmochin as a gametocide have been proved. 9. The course of treatment with these preparations is short, and this emphasizes the value of these drugs in malaria control. 10. These drugs should prove of great value in lowering malaria infection in connection with drainage projects, or in areas where drainage is not feasible because of costs. 11. Taking into consideration the epidemiology of malaria and cost of drainage, drug control is particularly applicable and advisable in rural areas. The figures in table 1 have been tested by the usual methods to show that the reduction of malarial infection in the drug treatment area is statistically significant.

Eight Weeks' Quinine Treatment for Malaria: A Report of Results as Observed in a Community with a High Malaria Incidence, in Dale County, Alabama

Eight Weeks' Quinine Treatment for Malaria: A Report of Results as Observed in a Community with a High Malaria Incidence, in Dale County, Alabama