A large focus of naturally acquired Plasmodium knowlesi infections in human beings

Part 1 The importance of blood-sucking insects. Part 2 The evolution of the blood-sucking habit: prolonged close association with vertebrates morphological pre-adaptation for piercing. Part 3 Feeding preferences of blood-sucking insects: host choice host choice and species complexes. Part 4 Location of the host: the behavioural framework of host location appetitive searching activation and orientation attraction movement between hosts. Part 5 Ingestion of the blood meal: vertebrate haemostasis insect anti-haemostatic factors probing stimulants phagostimulants mouthparts blood intake. Part 6 Managing the blood meal: midgut anatomy the blood meal gonotrophic concordance nutrition host hormones in the blood meal partitioning of resources from the blood meal autogeny. Part 7 Host - insect interactions: insect distribution on the surface of the host morphological specializations for life on the host host immune responses to insect salivary secretions behavioural defences of the host density dependent effects on feeding success. Part 8 Transmission of parasites by blood-sucking insects: transmission routes specificity in vector-parasite relationships origin of vector parasite relationships.

Biology of Blood-Sucking Insects

BACKGROUND: Primary malaria prevention on a large scale depends on two vector control interventions: indoor residual spraying (IRS) and insecticide-treated mosquito nets (ITNs). Historically, IRS has reduced malaria transmission in many settings in the world, but the health effects of IRS have never been properly quantified. This is important, and will help compare IRS with other vector control interventions. OBJECTIVES: To quantify the impact of IRS alone, and to compare the relative impacts of IRS and ITNs, on key malariological parameters. SEARCH STRATEGY: We searched the Cochrane Infectious Diseases Group Specialized Register (September 2009), CENTRAL (The Cochrane Library 2009, Issue 3), MEDLINE (1966 to September 2009), EMBASE (1974 to September 2009), LILACS (1982 to September 2009), mRCT (September 2009), reference lists, and conference abstracts. We also contacted researchers in the field, organizations, and manufacturers of insecticides (June 2007). SELECTION CRITERIA: Cluster randomized controlled trials (RCTs), controlled before-and-after studies (CBA) and interrupted time series (ITS) of IRS compared to no IRS or ITNs. Studies examining the impact of IRS on special groups not representative of the general population, or using insecticides and dosages not recommended by the World Health Organization (WHO) were excluded. DATA COLLECTION AND ANALYSIS: Two authors independently reviewed trials for inclusion. Two authors extracted data, assessed risk of bias and analysed the data. Where possible, we adjusted confidence intervals (CIs) for clustering. Studies were grouped into those comparing IRS with no IRS, and IRS compared with ITNs, and then stratified by malaria endemicity. MAIN RESULTS: IRS versus no IRSStable malaria (entomological inoculation rate (EIR) 1): Two studies; for incidence and prevalence, the malaria rates were higher in the IRS group compared to the ITN group in one study. Malaria incidence was higher in the IRS arm in India (risk ratio IRS:ITN = 1.48) and in South Africa (risk ratio 1.34 but the cluster unadjusted CIs included 1). For malaria prevalence, ITNs appeared to give better protection against any infection compared to IRS in India (risk ratio IRS:ITN = 1.70) and also for both P. falciparum (risk ratio IRS:ITN = 1.78) and P. vivax (risk ratio IRS:ITN = 1.37). AUTHORS' CONCLUSIONS: Historical and programme documentation has clearly established the impact of IRS. However, the number of high-quality trials are too few to quantify the size of effect in different transmission settings. The evidence from randomized comparisons of IRS versus no IRS confirms that IRS reduces malaria incidence in unstable malaria settings, but randomized trial data from stable malaria settings is very limited. Some limited data suggest that ITN give better protection than IRS in unstable areas, but more trials are needed to compare the effects of ITNs with IRS, as well as to quantify their combined effects

Indoor residual spraying for preventing malaria

The precise function of eosinophils in parasitic infection in vivo remains poorly understood despite eosinophils having been shown to be potent effectors in killing parasites in vitro. Although it has long been held that the primary function of the eosinophil is protection against helminth parasites, there are little data to prove this unequivocally. Moreover, eosinophils are responsible for a considerable amount of inflammatory pathology accompanying helminth infections. This article will provide an overview of our current knowledge about eosinophils and their role, both protective and pathogenetic, in parasitic helminth infections.

The role of eosinophils in host defense against helminth parasites

Haemosporida is a large group of vector-borne intracellular parasites that infect amphibians, reptiles, birds, and mammals. This group includes the different malaria parasites (Plasmodium spp.) that infect humans around the world. Our knowledge on the full life cycle of these parasites is most complete for those parasites that infect humans and, to some extent, birds. However, our current knowledge on haemosporidian life cycles is characterized by a paucity of information concerning the vector species responsible for their transmission among vertebrates. Moreover, our taxonomic and systematic knowledge of haemosporidians is far from complete, in particular because of insufficient sampling in wild vertebrates and in tropical regions. Detailed experimental studies to identify avian haemosporidian vectors are uncommon, with only a few published during the last 25 years. As such, little knowledge has accumulated on haemosporidian life cycles during the last three decades, hindering progress in ecology, evolution, and systematic studies of these avian parasites. Nonetheless, recently developed molecular tools have facilitated advances in haemosporidian research. DNA can now be extracted from vectors' blood meals and the vertebrate host identified; if the blood meal is infected by haemosporidians, the parasite's genetic lineage can also be identified. While this molecular tool should help to identify putative vector species, detailed experimental studies on vector competence are still needed. Furthermore, molecular tools have helped to refine our knowledge on Haemosporida taxonomy and systematics. Herein we review studies conducted on Diptera vectors transmitting avian haemosporidians from the late 1800s to the present. We also review work on Haemosporida taxonomy and systematics since the first application of molecular techniques and provide recommendations and suggest future research directions. Because human encroachment on natural environments brings human populations into contact with novel parasite sources, we stress that the best way to avoid emergent and reemergent diseases is through a program encompassing ecological restoration, environmental education, and enhanced understanding of the value of ecosystem services.

Diptera vectors of avian Haemosporidian parasites: untangling parasite life cycles and their taxonomy

Studies on filariasis in Malaya: the vertebrate hosts of Brugia malayi and B. pahangi.

Prior to 1960, no natural vectors were known for any species of simian malaria. In the course of investigations in Southeast Asia during the last 3 years, natural vectors for five of these malarias have been found; four have been transmitted in the laboratory. Natural vectors for the African and New World species are still unknown. In a series of tables, in the appendix, the authors summarize the literature on the potential experimental vectors. The ecology of simian malaria in Malaya is reviewed with particular reference to members of the Anopheles leucosphyrus group of mosquitoes in which three natural vectors of simian malaria have been identified. Because they are also vectors of human malaria, it is with this group of mosquitoes that the greatest possibility of a liaison between human and simian malaria exists in Southeast Asia. Interest in the vectors of simian malaria has been stimulated by the transmission of the Malayan monkey parasite Plasmodium cynomolgi bastianellii from man to monkeys by the bite of infected mosquitoes. The original infections in man were acquired accidentally in three different laboratories in the United States from experimentally infected Anopheles freeborni mosquitoes (Eyles et al., 1960; Schmidt et al., 1961). Subsequently other strains of Plasmodium cynomolgi, which is closely related to the human parasite P. vivax, were transmitted to man (Coatney et al., 1961) and it has been shown that man-to-man transmission of the parasite can occur under laboratory conditions. It is also known that the Central American monkey parasite, P. brasilianum, is transmissible to man (Contacos et al., 1963). These findings have led to efforts to determine the vectors of simian malaria in nature and to see whether there are ecological barriers Received for publication 8 October 1963. * Presented at the XVI International Congress of Zoology, Washington, D. C., on 21 August 1963 and sponsored by the American Society of Parasitologists and the British Society of Parasitology. t Present address: Division of Entomology, Commonwealth Scientific and Industrial Organization, Brisbane, Australia. which would prevent the transmission of monkey malaria to man under natural conditions in the field. These investigations have been centered mainly in Southeast Asia, particularly in Malaya, but it is pertinent at this stage to review briefly what is known about the vectors of simian malaria the world over. VECTORS OF SIMIAN MALARIA IN AFRICA Four members of the genus Plasmodium have been isolated from subhuman primates in Africa (Table I). Three species come from the great apes, Plasmodium reichenowi; a falciparum parasite of gorillas and chimpanzees; Plasmodium schwetzi, a vivax parasite of gorillas and chimpanzees; and Plasmodium malariae, a quartan parasite, similar to the human quartan parasite, of chimpanzees. The natural vectors of simian malaria are unknown in Africa, and information on the development of parasites under experimental conditions is scanty. Bray (1957) reported gut infections with Plasmodium reichenowi in experimentally fed Anopheles gambiae but mosquitoes dissected for gland infections were all negative. A similar observation was made by Rodhain and Lassman (1940) when they noted that A. atroparvus fed on chimpanzees infected with P. schwetzi developed gut infections, but no

https://www.jstor.org/stable/info/3275715

The vectors of simian malaria: identity, biology, and geographical distribution.

Studies on Filariasis in Malaya: Observations on the Development of Wuchereria malayi in Mansonia (Mansonioides) longipalpis.

1. 1) An attempt was made to transmit back to man a strain of Brugia malayi originally obtained from man and transmitted through a macaque monkey and thence to a cat. Two volunteers were inoculated with infective larvae of this strain which had developed in Mansonia longipalpis. Neither of these volunteers subsequently developed microfilariae. 2. 2) An attempt was also made to transmit to man a strain of B. pahangi, a species hitherto only known as an infection of animals. Two volunteers were inoculated with infective larvae from Armigeres obturbans which had fed on a cat carrying a strain of B. pahangi originally obtained from a naturally infected civet cat. 3. 3) One of the volunteers inoculated with B. pahangi developed microfilariae 84 days later, and these persisted in small numbers for a further 56 days. The microfilariae resembled B. pahangi morphologically, and the identification was confirmed by mosquito-feeding experiments and by experimental transmission to a cat from which an adult male B. pahangi was later recovered. The other volunteer did not develop microfilariae. 4. 4) All four volunteers suffered from episodes of lymphangitis, lymphadenitis, and oedema in the inoculated limb, starting in each instance about one month after the inoculation. 5. 5) Although there was no true leucocytosis, all four volunteers developed a relative increase in eosinophils with maxima ranging from 18 to 32 per cent. occurring 12 to 13 weeks after the inoculation. 6. 6) All volunteers showed positive complement-fixation tests and skin tests (to Dirofilaria antigen) about 12 weeks after the inoculation. 7. 7) One volunteer from each pair developed subcutaneous nodules in the inoculated arm about 4 months afterwards. 8. 8) The significance of these findings is discussed. B. pahangi must now be regarded as potentially infective to man. The clinical episodes are considered to be reactions to the immature developing worms, whereas the eosinophilia is more probably a response to some product of the adult worms. Subcutaneous nodules do not seem to have been described previously in association with filarial infection.

Experimental transmission of Brugia Malayi and B. Pahangi to man

(1960). Studies on Filariasis in Malaya: Field and Laboratory Investigations of the Vectors of a Rural Strain of Wuchereria Bancrofti. Annals of Tropical Medicine & Parasitology: Vol. 54, No. 1, pp. 78-91.

R. H. Wharton

Papers

Studies on filariasis in Malaya: the vertebrate hosts of Brugia malayi and B. pahangi.

The vectors of simian malaria: identity, biology, and geographical distribution.

Studies on Filariasis in Malaya: Observations on the Development of Wuchereria malayi in Mansonia (Mansonioides) longipalpis.

Experimental transmission of Brugia Malayi and B. Pahangi to man

Studies on filariasis in Malaya: field and laboratory investigations of the vectors of a rural strain of Wuchereria bancrofti.