Failure to eradicate Isospora belli diarrhoea despite immune reconstitution in adults with HIV--a case series.

Isospora belli causes diarrhoea in patients with AIDS. Most respond to targeted therapy and recommendations are that secondary prophylaxis can be stopped following immune reconstitution with ART. We report eight cases of chronic isosporiasis that persisted despite standard antimicrobial therapy, secondary prophylaxis, and good immunological and virological response to ART. Median CD4 nadir was 175.5 cells/mm(3) and median highest CD4 while symptomatic was 373 cells/mm(3). Overall 34% of stool samples and 63% of duodenal biopsy specimens were positive for oocytes. Four patients died, two remain symptomatic and two recovered. Possible explanations for persistence of symptoms include host factors such as antigen specific immune deficiency or generalised reduction in gut immunity. Parasite factors may include accumulating resistance to co-trimoxazole. Research is required to determine the optimum dose and duration of co-trimoxazole therapy and whether dual therapy may be necessary. Mortality was high and pending more data we recommend extended treatment with high-dose co-trimoxazole in similar cases.

Effect of isosporiasis prevention with toltrazuril on long-term pig performance.

The efficacy of toltrazuril treatment was assessed in two experiments in Polish swine herds. Experiment 1 included a toltrazuril treatment group, Group A (n = 410), and untreated control, Group B (n = 386). Time to sale in Group A was 108 days versus 120 days for Group B, with average body weights at sale of 114.2 kg and 108.8 kg, respectively (P < 0.05). In experiment 2, the health status and body weight gain of 238 piglets treated with toltrazuril (Group D) were compared to 235 untreated piglets (Group K). A similar difference was observed in average body weights of slaughtered animals, being on average 104 kg in Group D and 101 kg in Group K (P < 0.01). Animals from Group D were slaughtered 5 days earlier than animals from Group K (day 166 versus day 171). Data from clinical trials suggest treatment of coccidiosis with toltrazuril offering potential for improved animal welfare and yields, however this has remained unproven in field conditions in large swine production facilities. The present study confirms the efficacy of toltrazuril treatment when used in the field and the subsequent positive impact on time to weaning, time to market, and on weight gain at all time points.

Necrotic enteritis due to simultaneous infection with Isospora suis and clostridia in newborn piglets and its prevention by early treatment with toltrazuril.

In this study, 51 piglets originating from five different sows were included in the investigations. The animal source of all sows had a history of Clostridium perfringens type A (ß2) infection. The piglets of three sows (n = 31) were experimentally infected with Isospora suis within the first 4 h after birth and were randomly assigned to the treatment group or the sham-dosing group. The piglets of the two remaining sows (n = 20) served as I. suis-uninfected controls. Twelve hours post-infection, the animals in the treatment group (n = 15) were treated with toltrazuril (20 mg/kg BW, Baycox® 5% suspension). During an observation period of 14 days faecal consistency, faecal oocyst counts, faecal germ counts, mortality, body weight development and clinical status were recorded. One piglet per study group and litter was necropsied, and intestinal tissue samples were taken for histopathological investigations and in situ hybridisation on study days (SDs) 3 and 14. I. suis-infected but untreated piglets showed clinical disease resulting in liquefaction of faeces and decreased body weight development. In 59.2% of the observations, I. suis-infected but untreated piglets showed abnormal faecal consistencies whereas only 12.0% or respectively 4.4% of the faecal samples had a pasty consistency in the I. suis-infected-treated or in the control animals. The mean body weight at the end of the study was 3.37 kg in the I. suis-infected but untreated piglets while the average body weight in the I. suis-infected-treated animals was calculated as 4.42 kg and the control animal's mean body weight was 4.45 kg. Moreover, mortality, occurring between SDs 8 and 14, in this study group was 38.5% (n = 5), with 30.8% (n = 4) died from necrotic enteritis. In contrast, no piglets died in the I. suis-uninfected control group or in the toltrazuril-treated study group. The results of this study corroborate the hypothesis that simultaneous infection with I. suis and C. perfringens type A soon after birth leads to distinct interactions between the two pathogens and result in an increase in clinical disease, mortality and metabolically active C. perfringens type A.

Influence of toltrazuril treatment on parasitological parameters and health performance of piglets in the field--an Austrian experience.

Porcine coccidiosis caused by Isospora suis is one of the leading causes of neonatal diarrhea in suckling piglets. Currently the only registered drug for metaphylaxis is toltrazuril. To evaluate the effect of treatment on piglets from 7 Austrian farms without and 8 Austrian farms with toltrazuril application we examined oocyst excretion (including determination of oocysts per gram of feces; OPG), diarrhea (fecal score FS 1-4 with 3 and 4 being diarrhea), and general health (health score HS 1-4 with 3 and 4 describing poor health). Both groups included farms with different levels of hygiene. Samples from 265 litters without treatment, comprising 1588 individual samples, and 1548 samples from 258 treated litters were taken twice (around the 14th and the 21st day of life, respectively), examined by autofluorescence and, if positive, by McMaster counting. In both groups animals had less diarrhea and lower health scores during the second sampling but the treated piglets were always significantly healthier and had less diarrhea. The percentage of weaned piglets was higher in treated animals although this was not significant (p=0.052). In the first round of sampling 17.8% of the individual samples from untreated piglets were positive for oocysts (with a maximum prevalence on the 12-15th day of life) while in the treated piglets only 0.4% shed oocysts p<0.001). At the second sampling only 2.1% of the untreated animals and none of treated piglets excreted I. suis (p=0.083). Positive animals shed up to 8 × 10(3)OPG. There was an increased risk for infected piglets to develop diarrhea (odds ratio, OR 4.73) and poor health (OR 5.05) in untreated piglets, and poor hygiene without disinfection was identified as a risk factor for poor health (OR 1.90), diarrhea (OR 1.42) and oocyst excretion (OR 1.73). The risk of poor health (OR 2.89) and diarrhea (OR 1.44) was also increased for piglets under poor hygienic conditions receiving toltrazuril, so both metaphylaxis of coccidiosis and good hygiene are necessary to effectively control neonatal diarrhea. The costs of treatment are considerably lower than the estimated financial production losses. Therefore, treatment is recommended for farms where clinical coccidiosis is diagnosed.

Control of piglet coccidiosis by chemical disinfection with a cresol-based product (Neopredisan 135-1).

Isospora suis is a common pathogen in piggeries and one of the main causative agents of scours in suckling piglets. Besides specific treatment, optimised hygiene including chemical disinfection is considered essential in the control of isosporosis. The suitability of the cresol-based product Neopredisan 135-1(R) (NP) to inactivate oocysts in vitro and to reduce infection pressure in commercial piggeries was evaluated. Under in vitro conditions, NP at a final concentration of 2 or 4% induced lysis of more than 95% of sporulated oocysts at a contact time of 30 min and destroyed all oocysts after a contact time of 90 min or more. A total of six trials (T1-T6) were performed on two farms (I and II). T5 was split into two parts, T5/1 and T5/2. Two groups of litters kept in farrowing crates either disinfected conventionally before farrowing (controls, group C) or disinfected with 4% dilution of NP before farrowing and with 2% NP one to three times thereafter (group NP) were compared in each trial. Altogether, 81 litters were randomly allocated to group NP and 77 litters to group C (comprising a total of 1,465 piglets). Piglet faeces were collected individually 5 days after birth and six times thereafter in intervals of 2 or 3 days from four piglets per litter and microscopically examined for oocysts of I. suis. Diarrhoea scores, other clinical data (skin turgidity, coat length etc.), weights and loss of piglets until weaning were recorded. One trial (T3) could not be analysed because of insufficient cleaning before disinfection. In group C, litter prevalence of I. suis ranged between 40 and 80%. The proportion of positive litters was considerably reduced by approximately 50% in disinfected crates except for one trial, and the number of affected piglets decreased by up to 80%. Diarrhoea and oocyst excretion were significantly associated. Diarrhoea was less frequently observed in disinfected crates. In general, isosporosis appeared mild to subclinical, and no significant effects of disinfection on other clinical data, weight gain and number of weaned piglets were noted. It is concluded that NP efficiently inactivates oocysts of I. suis, and that additional disinfection after farrowing is suited to reduce infection pressure. No clear relation of infection prevalence to the frequency of intermediate disinfection (one, two or three times) was seen, and thus, single intermediate disinfection 1 week after farrowing is considered sufficient.

[Highly Active AntiRetroviral Therapy and opportunistic protozoan infections]. / La Highly Active AntiRetroviral Therapy e le infezioni protozoarie opportuniste.

Opportunistic parasite infections (OPIs) are an important cause of morbidity and mortality in persons infected with HIV. In industrialised countries, the use of Highly Active AntiRetroviral Therapy (HAART) results to be effective in suppressing the HIV viral load, with a quantitative and qualitative improvement in the CD4+ T-cell count followed by a strong reduction of opportunistic infections including those caused by parasites. These successes have been mainly attributed to the reconstitution of the cell immunity, which play the most important role in controlling OPIs. However, there are many clinical reports and several laboratory results, which suggest that the control of OPIs in HIV-positive persons under HAART is also induced by the anti-HIV protease inhibitors (PIs), which inhibit the aspartyl proteases of the parasites. The non-conventional use of HIV-PIs seems to be an alternative way for the treatment of parasitic infections, which should be deeply investigated. Of five longitudinal studies carried out before and after the introduction of HAART, four studies showed a strong reduction of toxoplasmic encephalitis (TE) in HIV-positive persons under HAART, whereas in another study, no difference was observed in the incidence rate of TE before and after the introduction of HAART. The influence of HAART in reducing TE has been also confirmed in a randomised, controlled clinical trial, which showed that there is no increase in the risk of developing TE after beginning HAART, even though HIV-infected persons with TE had a discontinuing prophylaxis for Toxoplasma gondii. Four HIV protease inhibitors were tested against the T. gondii virulent RH strain in vitro, alone or in association with pyrimethamine or sulfadiazine. Ritonavir and nelfinavir were highly inhibitory for the parasite growth. Furthermore, none of the antiviral drugs negatively affected the anti-Toxoplasma activity of pyrimethamine or sulfadiazine. In HIV-Leishmania co-infections, a changing pattern has been observed in the HAART era, characterised by a high rate of relapses, which could be explained by the increased survival rate resulting from the effective antiretroviral therapy. A 64.8% decrease of the visceral leishmaniasis incidence was detected after HAART began to be used extensively in Spain. In a large cohort study carried out in ten European countries and in Australia, the relative risk to contract cryptosporidiosis as the first AIDS defining disease was reduced by 96% in the HAART era. In Italy, the relative risk of death for cryptosporidiosis reduced of 74% in the period 1997-98, when HIV-positive persons received HAART. In a large study carried out in Italy, isosporiasis was included in the group of opportunistic infections, of which the relative hazards showed a reduction of 95% in the HAART era. Since 1997, there was the evidence that the use of HAART in persons with advanced HIV infection can improve chronic diarrhoea and lead to disappearance of Enterocytozoon bieneusi from the stools. Although the reconstitution of the cellular immunity seems to be the main factor influencing the reduction of OPIs in persons with AIDS who undergo HAART, there are clinical and microbiological evidences, as well as in vitro and in vivo results, which indicate direct effects of HIV-PIs on the proteases of opportunistic parasites. These findings stress the existence of non-conventional unexpected benefits of PIs in HAART against protozoa. In addition, this benefit of PIs has been demonstrated also for Candida albicans secreted aspartyl proteases and for P. carinii acid proteases. In spite of these important results, HIV PIs are still very toxic for humans, specially in cases of very long treatment, and no clinical trial has been carried out for persons at risk, such as children and pregnant women, because the priority was to reduce the severity of HIV and not the evaluation of possible side effects of the therapy. It follows that further researches are needed to establish the non-conventional use of HIV PIs. Furthermore, the study of PIs against specific aspartyl proteases of those opportunistic protozoa that cause severe and intractable diseases, could be considered an alternative way towards the development of new drugs that may prove effective against these infections.