Prevalence of antibody to Plasmodium falciparum antigens among feral Saimiri monkeys in the Amazon basin region of Peru

Health monitoring of non-human primate colonies

Recommendations of the Federation of European Laboratory Animal Science Associations (FELASA) Working Group on Non-Human Primate Health accepted by the FELASA Board of Management, 21 November 1998

FELASA Working Group on Non-Human Primate Health: H. Weber (Convenor), E. Berge, J. Finch, P. Heidt, F.-J. Kaup, G. Perretta, B. Verschuere & S. Wolfensohn

Detection of etiological agents of malaria in howler monkeys from Atlantic Forests, rescued in regions of São Paulo city, Brazil

BACKGROUND

In some states of the Brazilian extra-Amazonian region, such as the Atlantic Forest area, autochthonous human cases of malaria were related to simian malarias and vice versa.

METHODS

To verify the presence of Plasmodium, 50 blood samples of howler monkeys (Alouatta guariba clamitans) rescued from the Metropolitan Region of Saõ Paulo city, where the Atlantic Forest is present, were analyzed. The samples were submitted to microscopy (thin and thick blood smears), enzyme-linked immunosorbent assays (ELISA), indirect immunofluorescent assay (IFA), and polymerase chain reaction (PCR).

RESULTS

Only one smear showed forms reminiscent of Plasmodium vivax. In ELISA, the frequencies of antibodies against synthetic peptides corresponding to circumsporozoite protein of P. vivax VK210 'classic' (Pvc), P. vivax VK247, human P. vivax-like (Pvk and Pvl), P. malariae/P. brasilianum (Pm), and P. falciparum (Pf) were 24.0% (12/50) for Pvc, 8.0% (04/50) for Pvk, 6.0% (03/50) for Pvl, 24.0% (12/50) for Pm, and 28.0% (14/50) for Pf, while the frequency of antibodies against PvMSP119 recombinant proteins was 42.0% (21/50). No serum reacted against PfMSP1-19. In IFA,the seropositivity of antibodies against asexual forms of P. malariae was 31.3% (15/48). We utilized three PCR protocols to develop a molecular consensus (positive results in, at least, two protocols). The frequency of Plasmodium infections detected by PCR was 18.0% (09/50) for P. vivax, 4.0% (02/50) for P. malariae, and 76.0% (38/50) of samples were negative. The molecular consensus was not seen in 4.0% (02/50) of samples.

CONCLUSIONS

These results suggest that a possible interaction between human and simian malaria coming from a zoonotic cycle cannot be discarded because simians that live in the areas of the Atlantic Forest could play a role as a reservoir for Plasmodium.

Natural Plasmodium infections in Brazilian wild monkeys: reservoirs for human infections?

Four hundred and forty-eight samples of total blood from wild monkeys living in areas where human autochthonous malaria cases have been reported were screened for the presence of Plasmodium using microscopy and PCR analysis. Samples came from the following distinct ecological areas of Brazil: Atlantic forest (N=140), semideciduous Atlantic forest (N=257) and Cerrado (a savannah-like habitat) (N=51). Thick and thin blood smears of each specimen were examined and Plasmodium infection was screened by multiplex polymerase chain reaction (multiplex PCR). The frequency of Plasmodium infections detected by PCR in Alouatta guariba clamitans in the São Paulo Atlantic forest was 11.3% or 8/71 (5.6% for Plasmodium malariae and 5.6% for Plasmodium vivax) and one specimen was positive for Plasmodium falciparum (1.4%); Callithrix sp. (N=30) and Cebus apella (N=39) specimens were negative by PCR tests. Microscopy analysis was negative for all specimens from the Atlantic forest. The positivity rate for Alouatta caraya from semideciduous Atlantic forest was 6.8% (16/235) in the PCR tests (5.5, 0.8 and 0.4% for P. malariae, P. falciparum and P. vivax, respectively), while C. apella specimens were negative. Parasitological examination of the samples using thick smears revealed Plasmodium sp. infections in only seven specimens, which had few parasites (3.0%). Monkeys from the Cerrado (a savannah-like habitat) (42 specimens of A. caraya, 5 of Callithrix jacchus and 4 of C. apella) were negative in both tests. The parasitological prevalence of P. vivax and P. malariae in wild monkeys from Atlantic forest and semideciduous Atlantic forest and the finding of a positive result for P. falciparum in Alouatta from both types of forest support the hypothesis that monkeys belonging to this genus could be a potential reservoir. Furthermore, these findings raise the question of the relationship between simian and autochthonous human malaria in extra-Amazonian regions.

Malaria epidemiology in low-endemicity areas of the Atlantic Forest in the Vale do Ribeira, São Paulo, Brazil

We describe a seroepidemiological survey of malaria prevalence in two areas of low endemicity: Intervales State Park and Alto Ribeira State Tourist Park (PETAR). Both are located in the Vale do Ribeira in the state of São Paulo, Brazil. In this study, 318 subjects from both areas had their blood analyzed for the presence of malaria parasites by thin and thick blood smears. One hundred and sixty-three (51.2%) of the subjects were from Intervales State Park and 155 (48.7%) were from PETAR. We analyzed all the samples by indirect immunofluorescent assay (IFA) to detect antibodies against asexual forms of Plasmodium vivax and Plasmodium malariae and enzyme immunosorbent assay (ELISA) to detect the presence of antibodies against circumsporozoite proteins (CSP) from P. vivax VK210, human P. vivax-like/Plasmodium simiovale, P. vivax VK247 and Plasmodium brasilianum/P. malariae. The presence of Plasmodium species was detected by polymerase chain reaction (PCR). Eighteen of the subjects analyzed had positive IFA results for IgM against P. malariae antigens, and three others were positive for P. vivax antigens. Positivity of IgG antibodies against P. vivax detected by IFA was high in samples from both Intervales State Park and PETAR (32.0% and 49.0%, respectively), while positivity for P. malariae was lower (16.0% and 19.3% in Intervales State Park and PETAR, respectively). ELISA tests showed a higher prevalence of antibodies against P. vivax VK210 (35.0%) in samples from Intervales State Park and against human P. vivax-like (29.7%) in samples from PETAR. PCR reactions revealed the presence of parasites in several of the samples analyzed. In Intervales State Park, one subject was infected by P. malariae and two by Plasmodium falciparum, while in PETAR, one subject was positive for P. falciparum and three for both P. falciparum and P. vivax parasites. The areas where these parks are located belong to the Atlantic Forest habitat, and inhabitants frequently, see monkeys. Our data suggest that monkeys may constitute a natural reservoir for malaria in both areas.

Widespread occurrence of antibodies against circumsporozoite protein and against blood forms of Plasmodium vivax, P. falciparum and P. malariae in Brazilian wild monkeys

BACKGROUND

A survey of malaria antibodies was carried out over 7 years and a total of 777 serum samples from wild monkeys were collected in three distinct ecological areas of Brazil where autochthonous malaria has been reported: the 'Cerrado' (similar to savanna), the Atlantic Forest and the Atlantic Semideciduous Forest.

METHODS

We carried out enzyme-linked immunosorbent assay to investigate the presence of IgG antibodies against peptides of the circumsporozoite protein (CSP) repeat region of 'classic'Plasmodium vivax, P. vivax VK247, human P. vivax-like/P. simiovale, P. brasilianum/P. malariae and P. falciparum. We also carried out immunofluorescence assay with asexual forms of P. vivax, P. malariae and P. falciparum.

RESULTS

The high prevalence of antibodies against CSP in all areas indicates that the monkeys had intense contact with sporozoites from infected anophelines. The immune response against asexual forms of Plasmodium in the monkeys from the Atlantic Forest indicates the development of the infection.

CONCLUSIONS

We discuss the possibility of monkeys being malaria reservoirs in non-endemic areas.