The American Journal of Tropical Medicine and Hygiene - Volume 39, Issue 2, 1988

The NOTICE TO CONTRIBUTORS section on the inside back cover of the July issue of the JOURNAL contained the following statement:

“Page charges. For papers describing original research the subvention charge is $100.00 per page.”

This is in keeping with a policy adopted by the Councilors at the midyear meeting in Washington. It specifies a requirement for each author and his supporters to provide assistance to the Society for the operation of the JOURNAL and makes the amount of such financial support proportional to the length of the material published. The term subvention is properly used since this charge does not cover the cost of JOURNAL publication. The practice will eliminate, to a considerable degree, current page limitations on the size of each volume.

Effective as of 20 September 1988, the estimated subvention amount will be noted in the letter of acknowledgment provided to the author at the time each manuscript is received.

Malaria sporozoite rates and inoculation rates were measured over periods up to 25 months in the different anopheline species biting humans in 13 villages in Madang Province, Papua New Guinea. Analysis of three members of the Anopheles punctulatus complex, 68,458 An farauti, 36,779 An. koliensis, and 11,667 An. punctulatus caught in landing catches was made using monoclonal antibody based ELISAs to detect sporozoites of Plasmodium falciparum and P. vivax. Sporozoite rates ranged from 0%–5.5% in An. farauti, 0.2%–3.8% in An. koliensis, and 0%–3.3% in An. punctulatus. In addition, over 3,000 An. longirostris were analyzed and sporozoites were not detected in this species. No significant differences were observed between the three vector species in the densities of P. falciparum sporozoites (geometric mean 2,320). However, the geometric mean P. vivax sporozoite density was significantly higher in An. punctulatus (350) than in either An. koliensis (160) or An. farauti (150). An. koliensis was less susceptible to infections of P. falciparum or P. vivax than either An. farauti or An. punctulatus.

Variations in average sporozoite and inoculation rates were found among different villages, despite their close geographic proximity. Sporozoite and inoculation rates varied greatly within a village over time, but malaria transmission was perennial with a higher transmission during the wet season by An. koliensis and An. punctulatus.

An immunohistochemical assay was developed combining an avidin-biotin-glucose oxidase complex procedure (ABC-GO) with light microscopy to detect specific antibody against Plasmodium falciparum. Thin blood films were prepared from culture material of P. falciparum and fixed with acetone. Antibody was detected by successive incubations with test serum, biotinylated goat antihuman antibody, avidin-biotin-glucose oxidase complex, and glucose oxidase substrate. In the presence of reactive serum, a blue precipitate formed on the parasites and could be visually observed with a 40 × objective. Sera from patients with single infections for P. vivax or P. ovale were unreactive. No cross-reactivity was observed with sera from patients with rheumatoid arthritis, filariasis, amebiasis, schistosomiasis, dengue, scrub typhus, leptospirosis, or toxoplasmosis. The sensitivity of ABC-GO is comparable to that of the indirect fluorescent antibody test.

The magnitude of the antibody response to three distinct and defined antigens of Plasmodium falciparum was assessed in 144 inhabitants of the Kassa district (Haut Ogooué Province, Gabon), a region where malaria is mesoendemic. Antibodies against a polypeptide consisting of 40 (Asn-Ala-Asn-Pro) repeats of P. falciparum circumsporozoite protein [(NANP)40] were detected by ELISA. Antibodies against the fusion peptide 31.1, which consists of the N-terminal portion of the 190–200 kDa glycoprotein, were also detected by ELISA. Antibodies against ring-infected erythrocyte surface antigens (RESA), mainly the P. falciparum 155 kDa antigen (Pf155), were detected by IFA on glutaraldehyde-fixed P. falciparum infected red blood cells (IRBC). In addition, a standard IFA employing air-dried P. falciparum IRBC was used to detect antibodies against intraerythrocytic asexual forms. Parasitemia and spleen enlargement were also recorded.

The frequency of sera positive for specific antibodies increased with age for all the antigens tested. Plateau antibody levels were reached at different ages for the different antigens. Individual antibody responses varied in titer to the different antigens. Subjects with parasite-negative thick smears showed higher titers of anti-31.1 as well as an increased frequency of anti-RESA antibodies compared to subjects having positive smears. No differences in the titer and in the prevalence of anti-(NANP)40 antibodies were found between these groups. The results suggest that the antibody response against asexual blood stage antigens, especially anti-RESA and anti-31.1, may play a role in controlling parasitemia.

Cryosections of human red blood cells infected by Plasmodium falciparum were analyzed by energy dispersive x-ray microanalysis to determine the elemental composition of the parasites and their red cell hosts separately. The effects of two antimalarial drugs, qinghaosu and chloroquine, on potassium, sodium, and phosphorus concentrations were studied. Malarial infection causes a decrease in potassium concentration and an increase in sodium concentration in the host red cells. The drastic change in the cation composition, however, occurs only in red cells infected by late stage parasites (late trophozoite and schizont). Red cells infected by early stage parasites (ring stage) show only small changes in sodium concentration. Furthermore, the noninfected red cells in parasitized cultures show no difference in composition from those of normal red cells. Treatment of the parasitized cultures with qinghaosu (10-6 M) or chloroquine (10-6 M) for 8 hr causes phosphorus concentration of both early and late parasites to decrease. An 8 hr treatment with qinghaosu also produces a reduction in potassium and an increase in sodium concentrations in early and late parasites. In contrast, 8 hr treatment with chloroquine only causes a change in the sodium and potassium concentrations of the late stage parasites and does not affect the early stage parasites.

The drug sensitivity of 246 Plasmodium falciparum isolates was studied in vitro in five areas of Cameroon at the end of 1985. Results demonstrate that parasites resistant either to chloroquine, quinine, or mefloquine, or to two of these drugs, were prevalent in four of the areas investigated, but the drug response pattern varies widely from one area to another.

The recent explosive emergence of chloroquine resistance in the south of the country, where both prevalences and levels are very high (up to 86%), contrasts with only moderate levels of resistance in the north. This may be related to differences in transmission by mosquitoes between Sahel and forest areas.

Quinine resistance was observed in 24% of the isolates studied in vitro and was frequently associated with chloroquine resistance.

The presence of isolates responding poorly to mefloquine, observed mainly in northern Cameroon, suggests that resistance may occur in areas where the drug has never been used.

Twenty-four antigens of Bartonella bacilliformis, a bacterium which causes bartonellosis in residents of high altitude valleys of the Andes, were identified by immunoblot and immunoprecipitation using rabbit anti-Bartonella sera as well as sera of patients. The antigens were designated according to their relative molecular mass which ranged from 16 to 160 kDa. Twelve antigens were detected by antibodies in sera of bartonellosis patients using immunoblot, of which six antigens were detected by immunoprecipitation. Antigens 25, 46, 65, 75, 99, and 160 were identified ad probable cell wall antigens. Antigens 50, 65, and 75 detected long-persisting antibodies. Crude Bartonella antigen applied to ELISA reacted with anti-Chlamydia psittaci antibody as well as with antibody of unknown identity in human sera, whereas immunoblot and immunoprecipitation with Triton soluble antigens revealed Bartonella-specific results. Seven Bartonella antigens were prepared by high performance liquid chromatography of which one antigen (48 kDa) reacted Bartonella-specific when applied to ELISA. It was concluded that specificity of antibody determination with crude Bartonella antigen should be confirmed by either immunoblot or immunoprecipitation.

Sera from diverse clinical forms of American cutaneous leishmaniasis show remarkably different patterns of reactivity to Leishmania mexicana and L. braziliensis after absorption with these two species of Leishmania. The enhanced species specificity of absorbed sera was confirmed by reactions with well characterized reference strains. The use of pairs of enriched polyclonal sera from mucocutaneous and diffuse cutaneous leishmaniasis permits the preliminary classification of isolates in the L. mexicana or L. braziliensis complexes by a simple, inexpensive, and quantitative immunoassay.

A 27-year-old white woman from New York City acquired an infection by a Brugia species while she camped in the Amazon basin of Peru. She was infected by at least one adult male worm and one gravid female worm. Both worms were intact and in a lymphatic vessel of a right cervical lymph node. The lymph node and surrounding fibroadipose tissue contained many microfilariae. The male worm was 50 µm wide and the female, 100 µm. Both worms had thin (1 µm) cuticles with fine transverse striations. There were 3 to 4 somatic muscle cells per quadrant. Microfilariae had tails characteristic of the genus Brugia. Although specific identification was not possible from the available material, the worm closely resembled Brugia guyanensis, a parasite of the coatimundi (Nasua nasua) and the only species of Brugia known in South America.

A case of human brugiasis in a student from Gambela, Ethiopia, is reported. Ten sheathed microfilariae showing the Brugia genus characteristics were recovered from 1 ml of blood.

Mice were infected with 50 third stage larvae of Angiostrongylus cantonensis and treated orally with albendazole (Zentel®) in dosages of 5, 10, and 25 mg/kg/day begun 5, 10, or 15 days post-infection for 7, 14, or 21 consecutive days. The mice in each group were killed 3 days after cessation of treatment and the brains examined for parasites. Worms were recovered from the brains of all mice treated for 7 days, but recoveries from treated mice were significantly lower than from controls. Worm reduction was nearly 100% in mice treated for 14 days when treatment was initiated 5 and 10 days post-infection. Worms were found in the brain of mice treated for 14 days when treatment began at 15 and 20 days, but recovery rates were significantly lower than in controls. Similar results were obtained in animals treated for 21 days. Worm reduction rates were lower in animals given 5 mg/kg/day, but there was no significant difference in animals given higher dosages. Albendazole was effective in the treatment of A. cantonensis in mice when given within 15 days post-infection.

Previous studies demonstrated the usefulness of ultrasonography in diagnosing Symmers' periportal fibrosis. The prevalence and grade of Symmers' fibrosis was determined using ultrasonography in two villages in the Gezira region of Sudan and compared to standard clinical criteria. In El Dar 18% and Abu Jin 13% of the population had Symmers' fibrosis by ultrasonography. In contrast, only 6.3% in El Dar and 5.2% in Abu Jin with Symmers' fibrosis had splenomegaly, thus most of the population with Symmers' fibrosis would not have been diagnosed clinically. The degree of involvement was estimated by a set of previously defined criteria which ranged from mild (grade 1) to severe (grade 3). Involvement was greatest between 20–30 years and followed the age peak egg excretion rate by 5 years. The prevalence and degree of splenomegaly as well as the portal and splenic vein diameters increased with grade. The presence of hepatomegaly did not correlate with increasing grade. Ultrasonography is a much more sensitive technique than clinical evaluation in estimating the degree of Symmers' fibrosis in this population. A more accurate assessment of involvement will allow a more rational approach to the study of the pathophysiology of this complication and its eventual control.

Maguari virus has been classified as a subtype of Cache Valley virus. Seven Bunyamwera serogroup viruses (including prototypes Cache Valley and Maguari viruses), 4 viruses shown in previous tests as close antigenic relatives of Maguari or Cache Valley viruses, and Xingu virus were cross-tested by serum dilution-plaque reduction neutralization. All viruses were distinguishable from prototypes Cache Valley and Maguari viruses. The close antigenic relationships of the Cache Valley-like viruses demonstrate that multiple subtypes of Cache Valley virus exist and suggest that such antigenic variation is a phenotypic expression of considerable genetic diversity.

Distribution of Rift Valley fever virus (RVFV) was studied in the mosquito Culex pipiens. Mosquitoes were dissected on days 1–7 after an infectious bloodmeal, and RVFV plaque assays were performed on the legs, posterior midgut, ovaries, salivary glands, thoracic ganglia, and remaining organs and tissues (remnants). On days 7–12 and 14 following an infectious bloodmeal, mosquitoes were tested for their ability to transmit virus and then dissected. Dissemination (systemic infection) rates averaged 22% on days 1–14 and transmission rates 33% on days 7–14. There were no significant differences in the viral titers of midgut samples among the nondisseminated infected (virus limited to alimentary canal), disseminated infected nontransmitting, and transmitting groups of mosquitoes. The sequence of infection of the organs and tissues studied appeared to be as follows: midgut, hemolymph, remnants; salivary glands, ovaries, and thoracic ganglia. Some individuals were found to have disseminated infections as early as 12 hr following an infectious bloodmeal. Trauma, simulated by vigorous shaking immediately following the viremic bloodmeal, did not affect either infection or dissemination rates.

In a study begun in 1985, 1,026 children between the ages of 5 and 12 years, living in an area of low Japanese encephalitis (JE) infection, were vaccinated with live-attenuated JE vaccine, strain SA14-14-2. A group of 47 of the vaccinated children, 5–6 years of age, were examined for fever and other systemic reactions every other day for 2 weeks following vaccination. None of these children had temperatures >37.4°C or other systemic reactions during the observation period. No untoward reactions were reported in the remainder of the vaccinated group. After immunization, seroconversion rates in seronegative children were 100% (GMT 35.3, n = 11), 100% (GMT 31.7, n = 12), and 83.3% (GMT 23, n = 10) in groups receiving vaccine diluted 1:3, 1:5, and 1:50, respectively. These results indicate that the JE SA14-14-2 live-attenuated vaccine is immunogenic and safe for children.

Aedes mediovittatus, a forest and peridomestic mosquito found in the Caribbean area, has previously been shown to be highly susceptible to oral infection with dengue viruses in the laboratory. In the present study, the species was found to transmit all four dengue serotypes vertically (i.e., from one generation to another) at rates much higher than any observed previously for flaviviruses in mosquitoes. Vertical transmission rates (the percentage of parent females transmitting to one or more progeny) ranged up to 95%. Filial infection rates (the percentage of infected progeny) varied widely by family but rates ≥20% for individual families were not uncommon. Since Ae. mediovittatus feeds readily on humans and is relatively abundant, there is no apparent reason why it would not serve as a vector of dengue. If it does, vertical transmission of the virus in this species would contribute to the maintenance of viral endemicity.

This book is a first-rate, authoritative, and very practical training manual and field guide for persons who may become involved in the provision of medical care to refugees. The authors of the various chapters obviously have been selected by the editors with careful attention not only to their technical knowledge of specific subject areas, but one would guess, also for their actual experience in refugee settings. With some exceptions where knowledge seems to have been derived primarily from a review of the literature, the chapters mostly have the authoritative ring that comes only from having worked in refugee camps.

The book is divided into sections of Basic Considerations, Specialty Considerations in Patient Care, and Diagnosis and Management of Infectious Diseases. As the authors advise in their Preface, all the sections and chapters will, of course, not be equally applicable to all health care workers in all refugee settings.