Preliminary Entomological and Parasitological Studies in Humboldt , Aripuaná , Mato Grosso State , Brazil .

The preliminary results are given of studies on the sandfly fauna (Diptera: Psychodidae) in forest surrounding the Humboldt Research Centre, Muni¬ cipio of Aripuana, Mato Grosso State, Brazil. A total of 712 sandflies were obtained, including 26 different species: of these, 387 were caught off human bait; 317 from tree-trunks; 4 in a malaise¬ -trap; 3 in rodent baited oil traps; and 1 in a light-trap. Man-biting species were absent or very rare during studies in the dry season (August and September, 1974), but relatively abundant at the end of the rainy season (June, 1975): this suggests a seasonal transmission of leishmaniasis. The species at present known as Lutzomyia anduzei of Floch & Abonnenc (1942) was a major man-biter, this species is an important vector of cutaneous leishmaniasis in North Para, Brazil, and could be responsible for transmission in Aripuana. Among a total of 349 female sandflies dissected, promastigote flagellates were found in 2 Lutzomyia yuilli; epimastigote flagellates in 1 L. yuilli; a microsporidian in Psychodopygus ( 1) complexus; a gregarine, probably Monocystis chagasi, in P. davisi; and a nematode larva in P. complexus. Inoculation of the promastigote flagellates into the skin of hamsters failed to give Leishmania infections: possibly they were developmental stages of some other parasite. Two research workers of Project RADAM acquired cutaneous leishmaniasis in the Humboldt area; and 6 cases of malaria were diagnosed, 3 due to P. falciparum and 3 to P. vivax. Transmission of malaria was shown to be taking place in the camp site itself. Finally, man-biting "black-flies" (Diptera: Simuliidae) were found to be a serious problem, necessitating constant use of insect repellent.


INTRODUCTION
The rainy season, ever important in its influence on the phlebotomine population, is approximately from October to April, with the heaviest rainfall from January to March: with an average of about 2,000 mm per year.The altitude is 300 metres above sea level, and the climate is equatorial and very humid.Close to the Humboldt Centre, there already existed a small collection of thatched houses occupied by employees of a local rubber collector: sanitary conditions were very poor.The Humboldt Centre itself em-, ployed a small maintenance staff, who also tended the needs of visiting scientists.Apart from malaria, which was known to be common among the local inhabitants, there was no available information regarding leishmaniasis or other health problems.

MATERIALS AND METHODS
Anthropophilic sandflies were collected off human bait, at night, usually between the hours of 19.00 and 21.00.Capture sites were se lected from a variety of terrains, including high, dry forest ("terra firme") and more low-lying, swampy areas ("igapo").Rodent-baited, oiled traps were also set in the same localities, in attempts to indicate sandfly species attracted to rodents or other small forest mammals.They were variously baited with laboratory hamsters or the wild rodent Proechimys guyannensis.
Other sandflies were captured, with aspirators, from their resting-sites on the trunks of the larger trees, with a "malaisetrap", or in light-traps.

RESULTS
The 26 species of sandflies captured, by all methods, are listed in Table 1.Elongated forms were also abundant in the midgut, but none were seen in any part of the foregut.Infection in the second L. yuilli was similar, but restricted to the hindgut.

The first visit, in
A third specimen of L. yuilli was infected with stumpy epimastigote flagellates, probably the developmental stages of a trypanosome.They showed sluggish movements and were apparently limited to the midgut.Developmental stages and mature spores of a microsporidian were seen in the malpighian tubules of a single P. complexus, the parasite causing considerable deformation of the tubules.
A gregarine was noted in a specimen of P. davisi: both trophozoites and mature oocysts were present, the latter almost filling the accessory glands.Morphologically the parasite was similar to Monocystis chagasi, previously described in Lutzomyia longipalpis (Adler & Mayrink, 1961) and Lu.flaviscutellata (Lewis, et al., 1970).
Finally, a nematode larva was encountered in the hindgut of a P. complexus, which showed abundant remains of a previous blood-meal filling the midgut.
Hamsters were inoculated, intradermally.with the promastigotes from the 2 L. yuilli.On neither occasion, however, was, it possible to find Leishmania at the site of inoculation, one year later, either by direct examination or by NNN culture of skin-snips.

DISCUSSION
The observations to date are insufficient to draw very firm conclusions, but our failure to obtain sandflies from human bait during a whole week in the dry season does suggest that transmission of cutaneous leishmaniasis in this area may be limited to the rainy season and shortly afterwards.
Furthermore, subse quent captures with human bait showed a patchy distribution of some of the anthro pophilic species, which in turn suggests that endemic foci of the disease may share a similarly uneven pattern.

The apparent absence of the sandfly
Lutzomyia flaviscutellata surprised us, particu larly as we used traps baited with rodents, to which this insect is highly attracted.Lu. flaviscutellata is the vector of Leishmania me¬ xicana amazonensis in the Amazon region (Lainson & Shaw, 1968;Shaw & Lainson, 1968): we have found it to be common in almost all areas we have studied, including "gallery" forest in the Serra do Roncador area of Mato Grosso (Lainson & Shaw, 1970) which shares a similarly clearly demarked wet and dry season as that seen in Aripuana.
Perhaps the most significant observation during these studies has been the abundance of that species at present known as Lutzomyia anduzei of Floch & Abonnenc (1942) .This sandfly has recently been shown to be an important vector of L. braziliensis guyanensis, the causitive agent of cutaneous leishmaniasis ("pian-bois") in the extreme north of Para State (Lainson, et al., 1976).Whether or not it is also a vector in the Aripuana region remains to be seen.
The failure of promastigotes in L yuilli tc produce detectable Leishmania infections in the inoculated hamsters suggests one OT two things.
Either they were monogenetic fla gellates of this insect, or they were develop mental stages of another parasite taken up in a blood-meal from some wild mammal.In the former case one might expect the incidence of infection in L. yuilli to have been much higher and, in addition, we have yet to secure any definite evidence of any monogenetic fla gellate infection in the several thousand wild-caught sandflies we have dissected in Brazil.We feel, therefore, that the second hypothesis is most likely the correct one: in this respect Endotrypanum, the intra-erythrocytic trypanosomatid of the sloth Choloepus didactylus, remains a likely suspect.Shaw (1969) found this parasite to develop as a promastigote infection in the hindgut station of experi mentally infected sandflies, in Panama, and subsequently (unpublished observations) iso lated Endotrypanum from a naturally infected sandfly in that country.
The nature of the epimastigotes in the midgut of the third L. yuilli is equally proble matical.We have found trypanosome infections in a number of wild animals, any of which might have been the source of this insect's infection.It is worth noting, however, that apart form Endotrypanum, the sloth C. didactylus also harbours Trypanosoma spp., (Shaw, 1969): it is tempting to suggest, therefore, that both promastigote and epimastigote infections of L. yuilli may have originated from this same animal.
Little more can be added to our record of a microsporidian in P. complexus and a MonocystisAike gregarine in P. davisi, for time did not permit a detailed study of this mate rial.Both have been encountered in a variety of other sandfly species in the course of our studies elsewhere in Brazil (unpublished observations), and nematode larvae have also been seen on less frequent occasions.
Further study of sandflies in the Aripuana region is needed to resolve the question of the promastigote infections in L. yuilli, and to pinpoint the vectors and wild mammal reservoirs of Leishmania in this poorly studied area.

Fig
Fig. 1. -Location of the Humboldt Research Cen tre, Aripuaná Project.
the south, the Municipio of Aripuaná inclu des a large part of the Cinta-Larga indian reserve.
August, 1974, was well within the dry season and attempts to obtain sandflies from human bait were unsuccessful.Smali numbers were found on tree-trunks, however, and a rigorous search gave a total catch of 317.Only 4 specimens were caught in the malaise-trap, and 1 in a light-trap: no animal-baited traps were set on this occasion.from human bait during a total of 20 man-hours of catching, and all were P. davisi.No other method of capture was attempted and all material was used for taxonomy.The third visit to Aripuana was more fruitful, doubtless because it coincided with the end of the rainy season and the forest was noticably more moist.A total of 387 sandflies were caught from human bait in approximately 20 man-hours, and they included 11 different species.Rodent-baited traps gave poor results in all localities, providing only 2 female Pcomplexus and 1 female P. davisi: no other methods of capture were employed.We dissected 349 of the sandflies taken with human bait, and the 3 that were caught off the rodent-baited trap.Promastigote infections were found in 2 specimens of L. yuilli Young & Porter 1972.Most of the flagellates in the first fly were attached, singly or in clusters, to the wall of the pylorus ("hindgut triangle"), with smaller numbers extending throughout the ileum and down to the rectum: others were seen swimming rapidly in the lumen.The individual parasites varied greatly in form; from the classical, elongate "leptomonad" to stumpy, oval or almost rounded bodies.The length cf the single flagellum was also very variable; little more than the length of the body in the short or rounded forms attached to the gut wall, but often two or three times its length in the elongated, free parasites.Some of the latter were extremely thin, and moved with remarkable rapidity.

LIST OF SANDFLIES PSYCHODIDAE: PHLEBOTOMINAE CAPTURED IN FOREST SURROUNDING THE HUMBOLDT RESEARCH CENTRE. MUNIC1PIO DE ARIPUANA. THE STATE OF MATO GROSSO, BRAZIL Date and Method of Capture
( * ) -Females of L. dendrophila and L. shannoni indestinguishable.