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Fulltext Human infections with Sarcocystis species

Fayer R, Esposito DH, Dubey JP

Clin Microbiol Rev, 2015 Apr;28(2):295-311.
PMID: 25715644 DOI: 10.1128/CMR.00113-14

Recurrent outbreaks of muscular sarcocystosis among tourists visiting islands in Malaysia have focused international attention on sarcocystosis, a disease once considered rare in humans. Sarcocystis species require two hosts, definitive and intermediate, to complete their life cycle. Humans can serve as definitive hosts, with intestinal sarcocystosis for two species acquired from eating undercooked meat: Sarcocystis hominis, from beef, and Sarcocystis suihominis, from pork. Symptoms such as nausea, stomachache, and diarrhea vary widely depending on the number of cysts ingested but appear more severe with pork than with beef. Humans serve as intermediate hosts for Sarcocystis nesbitti, a species with a reptilian definitive host, and possibly other unidentified species, acquired by ingesting sporocysts from feces-contaminated food or water and the environment; infections have an early phase of development in vascular endothelium, with illness that is difficult to diagnose; clinical signs include fever, headache, and myalgia. Subsequent development of intramuscular cysts is characterized by myositis. Presumptive diagnosis based on travel history to tropical regions, elevated serum enzyme levels, and eosinophilia is confirmed by finding sarcocysts in muscle biopsy specimens. There is no vaccine or confirmed effective antiparasitic drug for muscular sarcocystosis, but anti-inflammatory drugs may reduce symptoms. Prevention strategies are also discussed.

Matched MeSH terms: Life Cycle Stages/physiology
Effects of life stages and feeding regimes on active movement behavior of the tropical bed bug, Cimex hemipterus (Hemiptera: Cimicidae)

How YF, Lee CY

J Med Entomol, 2010 May;47(3):305-12.
PMID: 20496576

This study examined the effects of different life stages (first, second, third, fourth, and five instars; adult females and adult males) and feeding regimes (starved and blood fed) on the active movement activity of the tropical bed bug, Cimex hemipterus (F.), under mixed-stage conditions. We used an extended arena made from Tygon tube coils and observed the movement frequency and movement distance at selected time intervals up to 120 h. The fifth instars and adult males and females showed significantly (P < 0.01) greater movement frequency compared with the other stages. The first and second instars showed limited movement (< 8 m) over the experimental period. Starved bed bugs showed greater movement frequency compared with blood-fed bed bugs, with the exception of adult females. Blood-fed adult females exhibited significantly (P < 0.01) greater movement frequency and distance compared with starved females. Blood-fed females moved up to 42.3 m over 120 h. Regression analysis between movement distance of the fifth instars and adults and the time intervals revealed a positive relationship (r2 = 0.6583; P < 0.01), suggesting that delays in bed bug control efforts will increase the risk of the greater infestation. During bed bug inspection, the presence of only late instars and adults in premises would indicate a new infestation, whereas an established infestation likely would consist of mixed stages.

Matched MeSH terms: Life Cycle Stages/physiology
Life history of Spodoptera exigua (Lepidoptera: Noctuidae) on various host plants

Azidah AA, Sofian-Azirun M

Bull. Entomol. Res., 2006 Dec;96(6):613-8.
PMID: 17201979

The incubation period of Spodoptera exigua (Hübner) was not influenced by the host plant, whereas larval development time and pupal period were affected. Larval development time was longest on shallot and lady's finger, followed by cabbage and long bean. Larvae did not develop beyond the first instar when fed on chilli. The pupal period was longer on lady's finger than on cabbage, shallot and long bean. Overall, adult longevity was not influenced by the host plant but there was a difference between female and male longevity among the host plants. Survival of S. exigua was affected by the host plant at the larval stage. The number of larval instars varied between 5 and 8 within and between the studied host plants. Long bean was found to be the most suitable host plant and provide the best food quality for S. exigua compared to the other host plants, as it allowed faster development, fewer larval instars and a higher survival rate.

Matched MeSH terms: Life Cycle Stages/physiology*
Polypeptides associated with in vitro cyst formation of Blastocystis hominis

Init I, Mak JW, Top S, Zulhainan Z, Prummongkol S, Nissapatorn V, et al.

Southeast Asian J. Trop. Med. Public Health, 2003 Dec;34(4):727-32.
PMID: 15115079

The objective of this study was to characterize the polypeptides associated with cysts of Blastocystis hominis. This form is believed to be infective and plays a role in parasite resistance to anti-B. hominis drugs currently used for treatment of Blastocystis associated diarrhea. Cysts were induced through in vitro culture of the parasite in complete medium supplemented with bacterial extract with trypticase, metronidazole or doxycycline. SDS-PAGE analysis showed almost similar polypeptide patterns of parasite extracts obtained from in vitro cultured parasites before and after exposure with the three supplements. Polypeptide bands at 76, 58.5, 48, 45, 40, 38, 32, 25 and 22 kDa were constantly seen in all antigenic preparations and no specific cyst-associated polypeptide was present. However, on immunoblot analysis, 3 out of 16 blastocystosis human sera identified a cyst-associated polypeptide at 60 kDa in all parasite extracts prepared from cultures with the three supplements. In addition, there were associated morphological changes detected in these parasites stained with acridine orange and observed under fluorescence microscopy. Metronidazole induced cyst forms (reddish cells) as early as 12 hours post-exposure; more cyst production (with stronger immunoblot bands) occurred after 24 hours exposure. However, cysts rupture with release and destruction of B. hominis daughters cells occurred after 48 hours exposure. Doxycycline induced less cyst-like forms at 24 hours (weaker 60 kDa band) and less destruction of the cysts (60 kDa band still present at 72 hours post exposure). Bacterial extract and trypticase also induced cysts at 12 hours with increasing numbers up to 72 hours exposure (corresponding increase in intensity of 60 kDa band from samples harvested at 12 to 72 hours post exposure) without any sign of deleterious effect on the parasite.

Matched MeSH terms: Life Cycle Stages/physiology*
Fulltext Changing domesticity of Aedes aegypti in northern peninsular Malaysia: reproductive consequences and potential epidemiological implications

Saifur RG, Dieng H, Hassan AA, Salmah MR, Satho T, Miake F, et al.

PLoS One, 2012;7(2):e30919.
PMID: 22363516 DOI: 10.1371/journal.pone.0030919

BACKGROUND: The domestic dengue vector Aedes aegypti mosquitoes breed in indoor containers. However, in northern peninsular Malaysia, they show equal preference for breeding in both indoor and outdoor habitats. To evaluate the epidemiological implications of this peridomestic adaptation, we examined whether Ae. aegypti exhibits decreased survival, gonotrophic activity, and fecundity due to lack of host availability and the changing breeding behavior.
METHODOLOGY/PRINCIPAL FINDINGS: This yearlong field surveillance identified Ae. aegypti breeding in outdoor containers on an enormous scale. Through a sequence of experiments incorporating outdoors and indoors adapting as well as adapted populations, we observed that indoors provided better environment for the survival of Ae. aegypti and the observed death patterns could be explained on the basis of a difference in body size. The duration of gonotrophic period was much shorter in large-bodied females. Fecundity tended to be greater in indoor acclimated females. We also found increased tendency to multiple feeding in outdoors adapted females, which were smaller in size compared to their outdoors breeding counterparts.
CONCLUSION/SIGNIFICANCE: The data presented here suggest that acclimatization of Ae. aegypti to the outdoor environment may not decrease its lifespan or gonotrophic activity but rather increase breeding opportunities (increased number of discarded containers outdoors), the rate of larval development, but small body sizes at emergence. Size is likely to be correlated with disease transmission. In general, small size in Aedes females will favor increased blood-feeding frequency resulting in higher population sizes and disease occurrence.

Matched MeSH terms: Life Cycle Stages/physiology